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Salgado-Puga K, Rothschild G. Exposure to sounds during sleep impairs hippocampal sharp wave ripples and memory consolidation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568283. [PMID: 38045371 PMCID: PMC10690295 DOI: 10.1101/2023.11.22.568283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Sleep is critical for the consolidation of recent experiences into long-term memories. As a key underlying neuronal mechanism, hippocampal sharp-wave ripples (SWRs) occurring during sleep define periods of hippocampal reactivation of recent experiences and have been causally linked with memory consolidation. Hippocampal SWR-dependent memory consolidation during sleep is often referred to as occurring during an "offline" state, dedicated to processing internally generated neural activity patterns rather than external stimuli. However, the brain is not fully disconnected from the environment during sleep. In particular, sounds heard during sleep are processed by a highly active auditory system which projects to brain regions in the medial temporal lobe, reflecting an anatomical pathway for sound modulation of hippocampal activity. While neural processing of salient sounds during sleep, such as those of a predator or an offspring, is evolutionarily adaptive, whether ongoing processing of environmental sounds during sleep interferes with SWR-dependent memory consolidation remains unknown. To address this question, we used a closed-loop system to deliver non-waking sound stimuli during or following SWRs in sleeping rats. We found that exposure to sounds during sleep suppressed the ripple power and reduced the rate of SWRs. Furthermore, sounds delivered during SWRs (On-SWR) suppressed ripple power significantly more than sounds delivered 2 seconds after SWRs (Off-SWR). Next, we tested the influence of sound presentation during sleep on memory consolidation. To this end, SWR-triggered sounds were applied during sleep sessions following learning of a conditioned place preference paradigm, in which rats learned a place-reward association. We found that On-SWR sound pairing during post-learning sleep induced a complete abolishment of memory retention 24 h following learning, while leaving memory retention immediately following sleep intact. In contrast, Off-SWR pairing weakened memory 24 h following learning as well as immediately following learning. Notably, On-SWR pairing induced a significantly larger impairment in memory 24 h after learning as compared to Off-SWR pairing. Together, these findings suggest that sounds heard during sleep suppress SWRs and memory consolidation, and that the magnitude of these effects are dependent on sound-SWR timing. These results suggest that exposure to environmental sounds during sleep may pose a risk for memory consolidation processes.
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Wang S, Li Z, Wang X, Li J, Wang X, Chen J, Li Y, Wang C, Qin L. Cortical and thalamic modulation of auditory gating in the posterior parietal cortex of awake mice. Cereb Cortex 2023:7032934. [PMID: 36757182 DOI: 10.1093/cercor/bhac539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 12/22/2022] [Accepted: 12/23/2022] [Indexed: 02/10/2023] Open
Abstract
Auditory gating (AG) is an adaptive mechanism for filtering out redundant acoustic stimuli to protect the brain against information overload. AG deficits have been found in many mental illnesses, including schizophrenia (SZ). However, the neural correlates of AG remain poorly understood. Here, we found that the posterior parietal cortex (PPC) shows an intermediate level of AG in auditory thalamocortical circuits, with a laminar profile in which the strongest AG is in the granular layer. Furthermore, AG of the PPC was decreased and increased by optogenetic inactivation of the medial dorsal thalamic nucleus (MD) and auditory cortex (AC), respectively. Optogenetically activating the axons from the MD and AC drove neural activities in the PPC without an obvious AG. These results indicated that AG in the PPC is determined by the integrated signal streams from the MD and AC in a bottom-up manner. We also found that a mouse model of SZ (postnatal administration of noncompetitive N-methyl-d-aspartate receptor antagonist) presented an AG deficit in the PPC, which may be inherited from the dysfunction of MD. Together, our findings reveal a neural circuit underlying the generation of AG in the PPC and its involvement in the AG deficit of SZ.
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Affiliation(s)
- Shuai Wang
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Zijie Li
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Xuejiao Wang
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Jinhong Li
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Xueru Wang
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Jingyu Chen
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Yingna Li
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
| | - Changming Wang
- Department of Anaesthesiology, The People's Hospital of China Medical University (Liaoning Provincial People's Hospital), No.33 Wenyi Road, Shenhe Area, Shenyang, Liaoning province 110067, People's Republic of China
| | - Ling Qin
- Department of Physiology, China Medical University, No. 77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning province 110122, People's Republic of China
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Billig AJ, Lad M, Sedley W, Griffiths TD. The hearing hippocampus. Prog Neurobiol 2022; 218:102326. [PMID: 35870677 PMCID: PMC10510040 DOI: 10.1016/j.pneurobio.2022.102326] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 06/08/2022] [Accepted: 07/18/2022] [Indexed: 11/17/2022]
Abstract
The hippocampus has a well-established role in spatial and episodic memory but a broader function has been proposed including aspects of perception and relational processing. Neural bases of sound analysis have been described in the pathway to auditory cortex, but wider networks supporting auditory cognition are still being established. We review what is known about the role of the hippocampus in processing auditory information, and how the hippocampus itself is shaped by sound. In examining imaging, recording, and lesion studies in species from rodents to humans, we uncover a hierarchy of hippocampal responses to sound including during passive exposure, active listening, and the learning of associations between sounds and other stimuli. We describe how the hippocampus' connectivity and computational architecture allow it to track and manipulate auditory information - whether in the form of speech, music, or environmental, emotional, or phantom sounds. Functional and structural correlates of auditory experience are also identified. The extent of auditory-hippocampal interactions is consistent with the view that the hippocampus makes broad contributions to perception and cognition, beyond spatial and episodic memory. More deeply understanding these interactions may unlock applications including entraining hippocampal rhythms to support cognition, and intervening in links between hearing loss and dementia.
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Affiliation(s)
| | - Meher Lad
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - William Sedley
- Translational and Clinical Research Institute, Newcastle University Medical School, Newcastle upon Tyne, UK
| | - Timothy D Griffiths
- Biosciences Institute, Newcastle University Medical School, Newcastle upon Tyne, UK; Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, UK; Human Brain Research Laboratory, Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, USA
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Leung LS, Ma J. Medial Septum Modulates Consciousness and Psychosis-Related Behaviors Through Hippocampal Gamma Activity. Front Neural Circuits 2022; 16:895000. [PMID: 35874429 PMCID: PMC9301478 DOI: 10.3389/fncir.2022.895000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Abnormally high-amplitude hippocampal gamma activity (30–100 Hz) in behaving animals is seen after a hippocampal seizure, following injection of phencyclidine (PCP) or ketamine, and transiently in a delirium stage during induction of general anesthesia. High-amplitude hippocampal gamma activity in behaving rats is associated with hyperactive behavior and impairment in sensorimotor gating and sensory gating. The medial septum is necessary for the high-amplitude gamma activity and abnormal behaviors observed following a hippocampal seizure or injection of PCP/ketamine. Glutamatergic projection of the hippocampus to the nucleus accumbens (NAC) and dopaminergic transmission in NAC is necessary for abnormal behaviors. Large hippocampal gamma waves are suggested to contribute to seizure-induced automatism following temporal lobe seizures, and the schizophrenia-like symptoms induced by PCP/ketamine. Low-amplitude gamma activity is found during general anesthesia, associated with loss of consciousness in humans and loss of righting reflex in animals. Local inactivation or lesion of the medial septum, NAC, and brain areas connected to the septohippocampal-NAC system attenuates the increase in hippocampal gamma and associated behavioral disruptions induced by hippocampal seizure or PCP/ketamine. Inactivation or lesion of the septohippocampal-NAC system decreases the dose of anesthetic necessary for gamma decrease and loss of consciousness in animals. Thus, it is proposed that the septohippocampal-NAC system serves to control consciousness and the behavioral hyperactivity and neural dysfunctions during psychosis.
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de la Salle S, Choueiry J, McIntosh J, Bowers H, Ilivitsky V, Knott V. N-methyl-D-aspartate receptor antagonism impairs sensory gating in the auditory cortex in response to speech stimuli. Psychopharmacology (Berl) 2022; 239:2155-2169. [PMID: 35348805 DOI: 10.1007/s00213-022-06090-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 02/15/2022] [Indexed: 10/18/2022]
Abstract
Deficits in early auditory sensory processing in schizophrenia have been linked to N-methyl-D-aspartate receptor (NMDAR) hypofunction, but the role of NMDARs in aberrant auditory sensory gating (SG) in this disorder is unclear. This study, conducted in 22 healthy humans, examined the acute effects of a subanesthetic dose of the NMDAR antagonist ketamine on SG as measured electrophysiologically by suppression of the P50 event-related potential (ERP) to the second (S2) relative to the first (S1) of two closely paired (500 ms) identical speech stimuli. Ketamine induced impairment in SG indices at sensor (scalp)-level and at source-level in the auditory cortex (as assessed with eLORETA). Together with preliminary evidence of modest positive associations between impaired gating and dissociative symptoms elicited by ketamine, tentatively support a model of NMDAR hypofunction underlying disturbances in auditory SG in schizophrenia.
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Affiliation(s)
- Sara de la Salle
- The Royal's Institute of Mental Health Research, Royal Ottawa Mental Health Centre, 1145 Carling Avenue, Ottawa, ON, K1Z 7K4, Canada
| | - Joelle Choueiry
- The Royal's Institute of Mental Health Research, Royal Ottawa Mental Health Centre, 1145 Carling Avenue, Ottawa, ON, K1Z 7K4, Canada.,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Judy McIntosh
- The Royal's Institute of Mental Health Research, Royal Ottawa Mental Health Centre, 1145 Carling Avenue, Ottawa, ON, K1Z 7K4, Canada
| | - Hayley Bowers
- Department of Psychology, University of Guelph, Guelph, ON, Canada
| | - Vadim Ilivitsky
- The Royal's Institute of Mental Health Research, Royal Ottawa Mental Health Centre, 1145 Carling Avenue, Ottawa, ON, K1Z 7K4, Canada
| | - Verner Knott
- The Royal's Institute of Mental Health Research, Royal Ottawa Mental Health Centre, 1145 Carling Avenue, Ottawa, ON, K1Z 7K4, Canada. .,Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.
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Vlcek P, Bob P. Schizophrenia, Bipolar Disorder and Pre-Attentional Inhibitory Deficits. Neuropsychiatr Dis Treat 2022; 18:821-827. [PMID: 35422621 PMCID: PMC9005071 DOI: 10.2147/ndt.s352157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 03/09/2022] [Indexed: 11/25/2022] Open
Abstract
According to recent findings schizophrenia and bipolar disorder as separate disease entities manifest similarities in neuropsychological functioning. Typical disturbances in both disorders are related to sensory gating deficits characterized by decreased inhibitory functions in responses to various insignificant perceptual signals which are experimentally tested by event related potentials (ERP) and measured P50 wave. In this context, recent findings implicate that disrupted binding and disintegration of consciousness in schizophrenia and bipolar disorder that are related to inhibitory deficits reflected in P50 response may explain similarities in psychotic disturbances in both disorders. With this aim, this review summarizes literature about P50 in both schizophrenia and bipolar disorder.
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Affiliation(s)
- Premysl Vlcek
- National Institute of Mental Health, Klecany, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Petr Bob
- Center for Neuropsychiatric Research of Traumatic Stress, Department of Psychiatry and UHSL, First Faculty of Medicine, Department of Psychiatry, & Faculty of Medicine Pilsen, Charles University, Prague, Czech Republic
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Arif Y, Wiesman AI, Christopher-Hayes NJ, Wilson TW. Aberrant inhibitory processing in the somatosensory cortices of cannabis-users. J Psychopharmacol 2021; 35:1356-1364. [PMID: 34694190 PMCID: PMC9659470 DOI: 10.1177/02698811211050557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Delta-9 tetrahydrocannabinol (THC) is a major exogenous psychoactive agent, which acts as a partial agonist on cannabinoid (CB1) receptors. THC is known to inhibit presynaptic neurotransmission and has been repeatedly linked to acute decrements in cognitive function across multiple domains. Previous electrophysiological studies of sensory gating have shown specific deficits in inhibitory processing in cannabis-users, but to date these findings have been limited to the auditory cortices, and the degree to which these aberrations extend to other brain regions remains largely unknown. METHODS We used magnetoencephalography (MEG) and a paired-pulse somatosensory stimulation paradigm to probe inhibitory processing in 29 cannabis-users (i.e. at least four times per month) and 41 demographically matched non-user controls. MEG responses to each stimulation were imaged in both the oscillatory and time domain, and voxel time-series data were extracted to quantify the dynamics of sensory gating, oscillatory gamma activity, evoked responses, and spontaneous neural activity. RESULTS We observed robust somatosensory responses following both stimulations, which were used to compute sensory gating ratios. Cannabis-users exhibited significantly impaired gating relative to non-users in somatosensory cortices, as well as decreased spontaneous neural activity. In contrast, oscillatory gamma activity did not appear to be affected by cannabis use. CONCLUSIONS We observed impaired gating of redundant somatosensory information and altered spontaneous activity in the same cortical tissue in cannabis-users compared to non-users. These data suggest that cannabis use is associated with a decline in the brain's ability to properly filter repetitive information and impairments in cortical inhibitory processing.
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Affiliation(s)
- Yasra Arif
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA,College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA
| | - Alex I. Wiesman
- College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA,Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | | | - Tony W. Wilson
- Institute for Human Neuroscience, Boys Town National Research Hospital, Boys Town, NE, USA,College of Medicine, University of Nebraska Medical Center, Omaha, NE, USA
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Hu H, Cui Y, Yang Y. Circuits and functions of the lateral habenula in health and in disease. Nat Rev Neurosci 2020; 21:277-295. [PMID: 32269316 DOI: 10.1038/s41583-020-0292-4] [Citation(s) in RCA: 256] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2020] [Indexed: 12/14/2022]
Abstract
The past decade has witnessed exponentially growing interest in the lateral habenula (LHb) owing to new discoveries relating to its critical role in regulating negatively motivated behaviour and its implication in major depression. The LHb, sometimes referred to as the brain's 'antireward centre', receives inputs from diverse limbic forebrain and basal ganglia structures, and targets essentially all midbrain neuromodulatory systems, including the noradrenergic, serotonergic and dopaminergic systems. Its unique anatomical position enables the LHb to act as a hub that integrates value-based, sensory and experience-dependent information to regulate various motivational, cognitive and motor processes. Dysfunction of the LHb may contribute to the pathophysiology of several psychiatric disorders, especially major depression. Recently, exciting progress has been made in identifying the molecular and cellular mechanisms in the LHb that underlie negative emotional state in animal models of drug withdrawal and major depression. A future challenge is to translate these advances into effective clinical treatments.
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Affiliation(s)
- Hailan Hu
- Department of Psychiatry of First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China. .,The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou, China. .,NHC and CAMS Key Laboratory of Medical Neurobiology, Mental Health Center, Zhejiang University, Hangzhou, China. .,Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, China. .,Fountain-Valley Institute for Life Sciences, Guangzhou, China.
| | - Yihui Cui
- The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou, China
| | - Yan Yang
- The MOE Frontier Science Center for Brain Research and Brain-Machine Integration, Zhejiang University School of Brain Science and Brain Medicine, Hangzhou, China
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Freedman R, Olsen-Dufour AM, Olincy A. P50 inhibitory sensory gating in schizophrenia: analysis of recent studies. Schizophr Res 2020; 218:93-98. [PMID: 32061454 PMCID: PMC7299819 DOI: 10.1016/j.schres.2020.02.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 01/22/2020] [Accepted: 02/07/2020] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Inhibitory sensory gating of the P50 cerebral evoked potential to paired auditory stimuli (S1, S2) is a widely used paradigm for the study of schizophrenia and related conditions. Its use to measure genetic, treatment, and developmental effects requires a metric with more stable properties than the simple ratio of the paired responses. METHODS This study assessed the ratio P50S2μV/P50S1μV and P50S2μV co-varied for P50S1μV in all 27 independent published studies that compared schizophrenia patients with healthy controls from 2000 to 2019. The largest study from each research group was selected. The Colorado research group's studies were excluded to eliminate bias from the first report of the phenomenon. RESULTS Across the 27 studies encompassing 1179 schizophrenia patients and 1091 healthy controls, both P50S2μV co-varied for P50S1μV and P50S2μV/P50S1μV significantly separated the patients from the controls (both P < 0.0001). Effect size for P50S2μV co-varied for P50S1μV is d' = 1.23. The normal distribution of P50S2μV co-varied for P50S1μV detected influences of maternal inflammation and effects on behavior in a recent developmental study, an emerging use for the P50 inhibitory gating measure. P50S2μV/P50S1μV was not normally distributed. Results from two multi-site NIMH genetics collaborations also support the use of P50S2μV as a biomarker. CONCLUSION Both methods detect an abnormality of cerebral inhibition in schizophrenia with high significance across multiple independent laboratories. The normal distribution of P50S2μV co-varied for P50S1μV makes it more suitable for studies of genetic, treatment, and other influences on the development and expression of inhibitory deficits in schizophrenia.
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Affiliation(s)
- Robert Freedman
- Department of Psychiatry, University of Colorado Denver School of Medicine, Anschutz Medical Center, Mail Stop F546, Aurora, CO 80045, USA.
| | - Amanda M. Olsen-Dufour
- Department of Psychiatry, University of Colorado Denver School of Medicine, Anschutz Medical Center, Mail Stop F546, Aurora, CO 80045 USA
| | - Ann Olincy
- Department of Psychiatry, University of Colorado Denver School of Medicine, Anschutz Medical Center, Mail Stop F546, Aurora, CO 80045 USA
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Zhang GW, Shen L, Zhong W, Xiong Y, Zhang LI, Tao HW. Transforming Sensory Cues into Aversive Emotion via Septal-Habenular Pathway. Neuron 2018; 99:1016-1028.e5. [PMID: 30122379 PMCID: PMC6126968 DOI: 10.1016/j.neuron.2018.07.023] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/02/2018] [Accepted: 07/17/2018] [Indexed: 11/23/2022]
Abstract
Emotions evoked by environmental cues are important for animal survival and life quality. However, neural circuits responsible for transforming sensory signals to aversive emotion and behavioral avoidance remain unclear. Here, we found that medial septum (MS) mediates aversion induced by both auditory and somatosensory stimuli. Ablation of glutamatergic or GABAergic MS neurons results in impaired or strengthened aversion, respectively. Optogenetic activation of the two cell types results in place avoidance and preference, respectively. Cell-type-specific screening reveals that glutamatergic MS projections to the lateral habenula (LHb) are responsible for the induction of aversion, which can be antagonized by GABAergic MS projections to LHb. Additionally, the sensory-induced place avoidance is facilitated by enhanced locomotion mediated by glutamatergic MS projections to the preoptic area. Thus, MS can transmit innately aversive signals via a bottom-up multimodal sensory pathway and produce concurrent emotional and motional effects, allowing animals to efficiently avoid unfavorable environments.
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Affiliation(s)
- Guang-Wei Zhang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, 30 Gaotanyan St., Chongqing 400038, China; Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Li Shen
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Wen Zhong
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Ying Xiong
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, 30 Gaotanyan St., Chongqing 400038, China.
| | - Li I Zhang
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
| | - Huizhong W Tao
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
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Leung LS, Ma J. Medial septum modulates hippocampal gamma activity and prepulse inhibition in an N-methyl-d-aspartate receptor antagonist model of schizophrenia. Schizophr Res 2018; 198:36-44. [PMID: 28801194 DOI: 10.1016/j.schres.2017.07.053] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 07/25/2017] [Accepted: 07/28/2017] [Indexed: 01/07/2023]
Abstract
We reviewed the participation of the septohippocampal system in an animal model of schizophrenia that was acutely induced by systemic injection of an N-methyl-d-aspartate (NMDA) receptor antagonist such as phencyclidine, MK-801 and ketamine. The NMDA receptor antagonist-induced model of schizophrenia is characterized by behavioral and electrophysiological disruptions, including a decrease in prepulse inhibition of the acoustic startle response (PPI), hyperlocomotion, decrease in gating of hippocampal auditory evoked potentials and robust increase in hippocampal gamma (30-100Hz) oscillations. Similar disruptions were also induced by a single electrographic seizure in the hippocampus. The behavioral and electrophysiological disruptions induced by an NMDA receptor antagonist can be reduced by inactivation or lesion of GABAergic neurons in the medial septum, deep brain stimulation of the medial septum or nucleus accumbens, or positive modulation of GABAB receptors. Our results suggest a close association between high-amplitude hippocampal gamma oscillations and psychosis-relevant behaviors including PPI loss, behavioral hyperactivity and loss in auditory gating. Abnormal electrophysiology suggests a disruption of somatic and apical dendritic inhibition in the hippocampus, resulting in distorted sensory integration, and impaired cognitive and memory processing. The hippocampus is suggested to be a hub in a brain network that participates in psychosis-relevant behaviors, through its direct projection to the nucleus accumbens, or through indirect connections via the entorhinal, cingulate and prefrontal cortices.
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Affiliation(s)
- L Stan Leung
- Department of Physiology and Pharmacology, The University of Western Ontario, London N6A 5C1, Canada.
| | - Jingyi Ma
- Department of Physiology and Pharmacology, The University of Western Ontario, London N6A 5C1, Canada
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12
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Skosnik PD, Hajós M, Cortes-Briones JA, Edwards CR, Pittman BP, Hoffmann WE, Sewell AR, D'Souza DC, Ranganathan M. Cannabinoid receptor-mediated disruption of sensory gating and neural oscillations: A translational study in rats and humans. Neuropharmacology 2018; 135:412-423. [PMID: 29604295 DOI: 10.1016/j.neuropharm.2018.03.036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 03/26/2018] [Accepted: 03/27/2018] [Indexed: 01/27/2023]
Abstract
Cannabis use has been associated with altered sensory gating and neural oscillations. However, it is unclear which constituent in cannabis is responsible for these effects, or whether these are cannabinoid receptor 1 (CB1R) mediated. Therefore, the present study in humans and rats examined whether cannabinoid administration would disrupt sensory gating and evoked oscillations utilizing electroencephalography (EEG) and local field potentials (LFPs), respectively. Human subjects (n = 15) completed four test days during which they received intravenous delta-9-tetrahydrocannabinol (Δ9-THC), cannabidiol (CBD), Δ9-THC + CBD, or placebo. Subjects engaged in a dual-click paradigm, and outcome measures included P50 gating ratio (S2/S1) and evoked power to S1 and S2. In order to examine CB1R specificity, rats (n = 6) were administered the CB1R agonist CP-55940, CP-55940+AM-251 (a CB1R antagonist), or vehicle using the same paradigm. LFPs were recorded from CA3 and entorhinal cortex. Both Δ9-THC (p < 0.007) and Δ9-THC + CBD (p < 0.004) disrupted P50 gating ratio compared to placebo, while CBD alone had no effect. Δ9-THC (p < 0.048) and Δ9-THC + CBD (p < 0.035) decreased S1 evoked theta power, and in the Δ9-THC condition, S1 theta negatively correlated with gating ratios (r = -0.629, p < 0.012 (p < 0.048 adjusted)). In rats, CP-55940 disrupted gating in both brain regions (p < 0.0001), and this was reversed by AM-251. Further, CP-55940 decreased evoked theta (p < 0.0077) and gamma (p < 0.011) power to S1, which was partially blocked by AM-251. These convergent human/animal data suggest that CB1R agonists disrupt sensory gating by altering neural oscillations in the theta-band. Moreover, this suggests that the endocannabinoid system mediates theta oscillations relevant to perception and cognition.
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Affiliation(s)
- Patrick D Skosnik
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA.
| | - Mihály Hajós
- Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Jose A Cortes-Briones
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Chad R Edwards
- Developmental Neuropsychological Services, P.C., South Bend, IN 46615, USA
| | - Brian P Pittman
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - William E Hoffmann
- Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Andrew R Sewell
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Deepak C D'Souza
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Mohini Ranganathan
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06510, USA
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Differential modulation of the auditory steady state response and inhibitory gating by chloral hydrate anesthesia. Sci Rep 2018; 8:3683. [PMID: 29487299 PMCID: PMC5829141 DOI: 10.1038/s41598-018-21920-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 02/13/2018] [Indexed: 11/17/2022] Open
Abstract
Auditory steady state response (ASSR) and inhibitory gating (IG) are electrophysiological examinations commonly used to evaluate the sensory and cognitive functions of the brain. In some clinic examinations and animal experiments, general anesthesia is necessary to conduct electrophysiological recordings. However, the effects of anesthesia on ASSR and IG remain unclear. For this reason, we recorded local field potentials though electrodes implanted in different brain areas of rats: the auditory cortex (AC), hippocampus (HC), amygdala (AMY), and prefrontal cortex (PFC), and compared the characteristics of ASSR and IG under anesthetized and conscious conditions. We found that ASSR signals were the strongest in the AC, and decreased sequentially in the HP, AMY, and PFC. Chloral hydrate anesthesia significantly reduced the power and phase-locking of ASSR in the AC, HP, and AMY. In contrast, the extent of IG in the AC was weakest and it increased sequentially in the HP, AMY, and PFC. Anesthesia had less effect on the extent of IG. Our results suggest that ASSR and IG may originate from different neural circuits and that IG is more resistant to general anesthesia and therefore better suited to examining the functioning of non-auditory brain regions.
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Qi R, Li J, Wu X, Geng X, Chen N, Yu H. Effects of Ketamine on Basal Gamma Band Oscillation and Sensory Gating in Prefrontal Cortex of Awake Rats. Neurosci Bull 2018; 34:457-464. [PMID: 29380249 DOI: 10.1007/s12264-018-0208-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 12/11/2017] [Indexed: 01/03/2023] Open
Abstract
Gamma band oscillation (GBO) and sensory gating (SG) are associated with many cognitive functions. Ketamine induces deficits of GBO and SG in the prefrontal cortex (PFC). However, the time-courses of the effects of different doses of ketamine on GBO power and SG are poorly understood. Studies have indicated that GBO power and SG have a common substrate for their generation and abnormalities. In this study, we found that (1) ketamine administration increased GBO power in the PFC in rats differently in the low- and high-dose groups; (2) auditory SG was significantly lower than baseline in the 30 mg/kg and 60 mg/kg groups, but not in the 15 mg/kg and 120 mg/kg groups; and (3) changes in SG and basal GBO power were significantly correlated in awake rats. These results indicate a relationship between mechanisms underlying auditory SG and GBO power.
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Affiliation(s)
- Renli Qi
- Second Department of Neurosurgery, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, China
| | - Jinghui Li
- Second Department of Neurosurgery, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, China
| | - Xujun Wu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China
| | - Xin Geng
- Second Department of Neurosurgery, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, China
| | - Nanhui Chen
- State Key Laboratory of Brain and Cognitive Science, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China.
| | - Hualin Yu
- Second Department of Neurosurgery, First Affiliated Hospital of Kunming Medical University, Kunming, 650032, China.
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Zhang GW, Sun WJ, Zingg B, Shen L, He J, Xiong Y, Tao HW, Zhang LI. A Non-canonical Reticular-Limbic Central Auditory Pathway via Medial Septum Contributes to Fear Conditioning. Neuron 2018; 97:406-417.e4. [PMID: 29290554 PMCID: PMC5798467 DOI: 10.1016/j.neuron.2017.12.010] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 11/06/2017] [Accepted: 12/05/2017] [Indexed: 11/26/2022]
Abstract
In the mammalian brain, auditory information is known to be processed along a central ascending pathway leading to auditory cortex (AC). Whether there exist any major pathways beyond this canonical auditory neuraxis remains unclear. In awake mice, we found that auditory responses in entorhinal cortex (EC) cannot be explained by a previously proposed relay from AC based on response properties. By combining anatomical tracing and optogenetic/pharmacological manipulations, we discovered that EC received auditory input primarily from the medial septum (MS), rather than AC. A previously uncharacterized auditory pathway was then revealed: it branched from the cochlear nucleus, and via caudal pontine reticular nucleus, pontine central gray, and MS, reached EC. Neurons along this non-canonical auditory pathway responded selectively to high-intensity broadband noise, but not pure tones. Disruption of the pathway resulted in an impairment of specifically noise-cued fear conditioning. This reticular-limbic pathway may thus function in processing aversive acoustic signals.
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Affiliation(s)
- Guang-Wei Zhang
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, 30 Gaotanyan St., Chongqing, 400038, China; Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Wen-Jian Sun
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Brian Zingg
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Neuroscience Graduate Program, University of Southern California, Los Angeles, CA 90089, USA
| | - Li Shen
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Jufang He
- Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong
| | - Ying Xiong
- Department of Neurobiology, Chongqing Key Laboratory of Neurobiology, Third Military Medical University, 30 Gaotanyan St., Chongqing, 400038, China.
| | - Huizhong W Tao
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
| | - Li I Zhang
- Zilkha Neurogenetic Institute, Department of Physiology and Neuroscience, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA.
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Ma J, Stan Leung L. Effects of GABA-B receptor positive modulator on ketamine-induced psychosis-relevant behaviors and hippocampal electrical activity in freely moving rats. Psychopharmacology (Berl) 2017; 234:3129-3142. [PMID: 28756462 DOI: 10.1007/s00213-017-4705-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 07/08/2017] [Indexed: 02/07/2023]
Abstract
RATIONALE Decreased GABAB receptor function is proposed to mediate some symptoms of schizophrenia. OBJECTIVES In this study, we tested the effect of CGP7930, a GABAB receptor positive allosteric modulator, on ketamine-induced psychosis-relevant behaviors and hippocampal electrical activity in behaving rats. METHODS Electrodes were bilaterally implanted into the hippocampus, and cannulae were placed into the lateral ventricles of Long-Evans rats. CGP7930 or vehicle was injected intraperitoneally (i.p.) or intracerebroventricularly (i.c.v.), alone or 15 min prior to ketamine (3 mg/kg, subcutaneous) injection. Paired click auditory evoked potentials in the hippocampus (AEP), prepulse inhibition (PPI), and locomotor activity were recorded before and after drug injection. RESULTS CGP7930 at doses of 1 mg/kg (i.p.) prevented ketamine-induced deficit of PPI. CGP7930 (1 mg/kg i.p.) also prevented the decrease in gating of hippocampal AEP and the increase in hippocampal gamma (65-100 Hz) waves induced by ketamine. Unilateral i.c.v. infusion of CGP7930 (0.3 mM/1 μL) also prevented the decrease in gating of hippocampal AEP induced by ketamine. Ketamine-induced behavioral hyperlocomotion was suppressed by 5 mg/kg i.p. CGP7930. CGP7930 alone, without ketamine, did not significantly affect integrated PPI, locomotion, gating of hippocampal AEP, or gamma waves. CGP7930 (1 mg/kg i.p.) increased heterosynaptically mediated paired pulse depression in the hippocampus, a measure of GABAB receptor function in vivo. CONCLUSIONS CGP7930 reduces the behavioral and electrophysiological disruptions induced by ketamine in animals, and the hippocampus may be one of the neural targets where CGP7930 exerts its actions.
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Affiliation(s)
- Jingyi Ma
- Department of Physiology and Pharmacology, The University of Western Ontario, Medical Sciences Building, London, ON, N6A 5C1, Canada.
| | - L Stan Leung
- Department of Physiology and Pharmacology, The University of Western Ontario, Medical Sciences Building, London, ON, N6A 5C1, Canada.,Graduate Program in Neuroscience, The University of Western Ontario, London, N6A 5C1, Canada
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17
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Ma J, Leung LS. Dual Effects of Limbic Seizures on Psychosis-Relevant Behaviors Shown by Nucleus Accumbens Kindling in Rats. Brain Stimul 2016; 9:762-769. [PMID: 27267861 PMCID: PMC4980124 DOI: 10.1016/j.brs.2016.05.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/11/2016] [Accepted: 05/16/2016] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND A paradox in epilepsy and psychiatry is that temporal lobe epilepsy is often predisposed to schizophrenic-like psychosis, whereas convulsive therapy can relieve schizophrenic symptoms. We have previously demonstrated that the nucleus accumbens is a key structure in mediating postictal psychosis induced by a hippocampal electrographic seizure. OBJECTIVE/HYPOTHESIS The purpose of this study is to test a hypothesis that accumbens kindling cumulating in a single (1-time) or repeated (5-times) convulsive seizures have different effects on animal models of psychosis. METHODS Electrical stimulation at 60 Hz was applied to nucleus accumbens to evoke afterdischarges until one, or five, convulsive seizures that involved the hind limbs (stage 5 seizures) were attained. Behavioral tests, performed at 3 days after the last seizure, included gating of hippocampal auditory evoked potentials (AEP) and prepulse inhibition to an acoustic startle response (PPI), tested without drug injection or after ketamine (3 mg/kg s.c.) injection, as well as locomotion induced by ketamine or methamphetamine (1 mg/kg i.p.). RESULTS Compared to non-kindled control rats, 1-time, but not 5-times, convulsive seizures induced PPI deficit and decreased gating of hippocampal AEP, without drug injection. Compared to non-kindled rats, 5-times, but not 1-time, convulsive seizures antagonized ketamine-induced hyperlocomotion, ketamine-induced PPI deficit and AEP gating decrease. However, both 1- and 5-times convulsive seizures significantly enhanced methamphetamine-induced locomotion as compared to non-kindled rats. CONCLUSIONS Accumbens kindling ending with 1 convulsive seizure may induce schizophrenic-like behaviors, while repeated (≥5) convulsive seizures induced by accumbens kindling may have therapeutic effects on dopamine independent psychosis.
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Affiliation(s)
- Jingyi Ma
- Department of Physiology and Pharmacology, The University of Western Ontario, Medical Sciences Building, London, ON, Canada N6A 5C1.
| | - L Stan Leung
- Department of Physiology and Pharmacology, The University of Western Ontario, Medical Sciences Building, London, ON, Canada N6A 5C1; Graduate Program of Neuroscience, The University of Western Ontario, Medical Sciences Building, London, ON, Canada N6A 5C1
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18
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Smucny J, Stevens KE, Olincy A, Tregellas JR. Translational utility of rodent hippocampal auditory gating in schizophrenia research: a review and evaluation. Transl Psychiatry 2015; 5:e587. [PMID: 26101850 PMCID: PMC4490287 DOI: 10.1038/tp.2015.77] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/14/2015] [Accepted: 05/04/2015] [Indexed: 01/15/2023] Open
Abstract
Impaired gating of the auditory evoked P50 potential is one of the most pharmacologically well-characterized features of schizophrenia. This deficit is most commonly modeled in rodents by implanted electrode recordings from the hippocampus of the rodent analog of the P50, the P20-N40. The validity and effectiveness of this tool, however, has not been systematically reviewed. Here, we summarize findings from studies that have examined the effects of pharmacologic modulation on gating of the rodent hippocampal P20-N40 and the human P50. We show that drug effects on the P20-N40 are highly predictive of human effects across similar dose ranges. Furthermore, mental status (for example, anesthetized vs alert) does not appear to diminish the predictive capacity of these recordings. We then discuss hypothesized neuropharmacologic mechanisms that may underlie gating effects for each drug studied. Overall, this review supports continued use of hippocampal P20-N40 gating as a translational tool for schizophrenia research.
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Affiliation(s)
- J Smucny
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - K E Stevens
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - A Olincy
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - J R Tregellas
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Research Service, Denver VA Medical Center, Denver, CO, USA
- Department of Psychiatry, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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19
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Knott V, Smith D, de la Salle S, Impey D, Choueiry J, Beaudry E, Smith M, Saghir S, Ilivitsky V, Labelle A. CDP-choline: effects of the procholine supplement on sensory gating and executive function in healthy volunteers stratified for low, medium and high P50 suppression. J Psychopharmacol 2014; 28:1095-108. [PMID: 25315828 DOI: 10.1177/0269881114553254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Diminished auditory sensory gating and associated neurocognitive deficits in schizophrenia have been linked to altered expression and function of the alpha-7 nicotinic acetycholinergic receptor (α7 nAChR), the targeting of which may have treatment potential. Choline is a selective α7 nAChR agonist and the aim of this study was to determine whether cytidine 5'-diphosphocholine (CDP-choline), or citicoline, a dietary source of choline, increases sensory gating and cognition in healthy volunteers stratified for gating level. In a randomized, placebo-controlled, double-blind design involving acute administration of low, moderate doses (500 mg, 1000 mg) of CDP-choline, 24 healthy volunteers were assessed for auditory gating as indexed by suppression of the P50 event-related potential (ERP) in a paired-stimulus (S1, S2) paradigm, and for executive function as measured by the Groton Maze Learning Task (GMLT) of the CogState Schizophrenia Battery. CDP-choline improved gating (1000 mg) and suppression of the S2 P50 response (500 mg, 1000 mg), with the effects being selective for individuals with low gating (suppression) levels. Tentative support was also shown for increased GMLT performance (500 mg) in low suppressors. These preliminary findings with CDP-choline in a healthy, schizophrenia-like surrogate sample are consistent with a α7 nAChR mechanism and support further trials with choline as a pro-cognitive strategy.
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Affiliation(s)
- Verner Knott
- Institute of Mental Health Research, University of Ottawa, Ottawa, ON, Canada Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada School of Psychology, University of Ottawa, Ottawa, ON, Canada Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
| | - Dylan Smith
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | | | - Danielle Impey
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Joelle Choueiry
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Elise Beaudry
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Meaghan Smith
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Salman Saghir
- School of Psychology, University of Ottawa, Ottawa, ON, Canada
| | - Vadim Ilivitsky
- Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
| | - Alain Labelle
- Department of Psychiatry, University of Ottawa, Ottawa, ON, Canada
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20
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Vlcek P, Bob P, Raboch J. Sensory disturbances, inhibitory deficits, and the P50 wave in schizophrenia. Neuropsychiatr Dis Treat 2014; 10:1309-15. [PMID: 25075189 PMCID: PMC4106969 DOI: 10.2147/ndt.s64219] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sensory gating disturbances in schizophrenia are often described as an inability to filter redundant sensory stimuli that typically manifest as inability to gate neuronal responses related to the P50 wave, characterizing a decreased ability of the brain to inhibit various responses to insignificant stimuli. It implicates various deficits of perceptual and attentional functions, and this inability to inhibit, or "gate", irrelevant sensory inputs leads to sensory and information overload that also may result in neuronal hyperexcitability related to disturbances of habituation mechanisms. These findings seem to be particularly important in the context of modern electrophysiological and neuroimaging data suggesting that the filtering deficits in schizophrenia are likely related to deficits in the integrity of connections between various brain areas. As a consequence, this brain disintegration produces disconnection of information, disrupted binding, and disintegration of consciousness that in terms of modern neuroscience could connect original Bleuler's concept of "split mind" with research of neural information integration.
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Affiliation(s)
- Premysl Vlcek
- Center for Neuropsychiatric Research of Traumatic Stress, Department of Psychiatry and UHSL, First Faculty of Medicine, Charles University, Prague, Czech Republic
| | - Petr Bob
- Center for Neuropsychiatric Research of Traumatic Stress, Department of Psychiatry and UHSL, First Faculty of Medicine, Charles University, Prague, Czech Republic ; Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic
| | - Jiri Raboch
- Center for Neuropsychiatric Research of Traumatic Stress, Department of Psychiatry and UHSL, First Faculty of Medicine, Charles University, Prague, Czech Republic
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21
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Septo-hippocampal GABAergic signaling across multiple modalities in awake mice. Nat Neurosci 2013; 16:1182-4. [PMID: 23912949 DOI: 10.1038/nn.3482] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 06/24/2013] [Indexed: 11/09/2022]
Abstract
Hippocampal interneurons receive GABAergic input from the medial septum. Using two-photon Ca(2+) imaging of axonal boutons in hippocampal CA1 of behaving mice, we found that populations of septo-hippocampal GABAergic boutons were activated during locomotion and salient sensory events; sensory responses scaled with stimulus intensity and were abolished by anesthesia. We found similar activity patterns among boutons with common putative postsynaptic targets, with low-dimensional bouton population dynamics being driven primarily by presynaptic spiking.
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22
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Dissanayake DW, Mason R, Marsden CA. Sensory gating, Cannabinoids and Schizophrenia. Neuropharmacology 2013; 67:66-77. [DOI: 10.1016/j.neuropharm.2012.10.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 10/10/2012] [Accepted: 10/20/2012] [Indexed: 12/12/2022]
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Zhang H, Lin SC, Nicolelis MAL. A distinctive subpopulation of medial septal slow-firing neurons promote hippocampal activation and theta oscillations. J Neurophysiol 2011; 106:2749-63. [PMID: 21865435 PMCID: PMC3214118 DOI: 10.1152/jn.00267.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 08/23/2011] [Indexed: 01/08/2023] Open
Abstract
The medial septum-vertical limb of the diagonal band of Broca (MSvDB) is important for normal hippocampal functions and theta oscillations. Although many previous studies have focused on understanding how MSVDB neurons fire rhythmic bursts to pace hippocampal theta oscillations, a significant portion of MSVDB neurons are slow-firing and thus do not pace theta oscillations. The function of these MSVDB neurons, especially their role in modulating hippocampal activity, remains unknown. We recorded MSVDB neuronal ensembles in behaving rats, and identified a distinct physiologically homogeneous subpopulation of slow-firing neurons (overall firing <4 Hz) that shared three features: 1) much higher firing rate during rapid eye movement sleep than during slow-wave (SW) sleep; 2) temporary activation associated with transient arousals during SW sleep; 3) brief responses (latency 15∼30 ms) to auditory stimuli. Analysis of the fine temporal relationship of their spiking and theta oscillations showed that unlike the theta-pacing neurons, the firing of these "pro-arousal" neurons follows theta oscillations. However, their activity precedes short-term increases in hippocampal oscillation power in the theta and gamma range lasting for a few seconds. Together, these results suggest that these pro-arousal slow-firing MSvDB neurons may function collectively to promote hippocampal activation.
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Affiliation(s)
- Hao Zhang
- Dept. of Neurobiology, Duke Univ. Medical Center, Durham, NC 27705, USA.
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GABA(B) receptor blockade in the hippocampus affects sensory and sensorimotor gating in Long-Evans rats. Psychopharmacology (Berl) 2011; 217:167-76. [PMID: 21484240 DOI: 10.1007/s00213-011-2274-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Accepted: 03/14/2011] [Indexed: 10/18/2022]
Abstract
RATIONALE Sensory and sensorimotor gating deficits are observed in schizophrenia. GABA(B) receptor deficiency is also detected in the hippocampus of schizophrenic patients. OBJECTIVES The present study tested the hypothesis that GABA(B) receptors in the hippocampus contribute to paired-pulse gating of hippocampal auditory-evoked potentials (AEP) and auditory prepulse inhibition (PPI) in Long-Evans rats. METHODS Gating of hippocampal AEP, or PPI, was examined before and after administration of GABA(B) receptor antagonist, CGP56999A or CGP35348, or saline was administered either systemically (intra-peritoneally (i.p.)) or infused bilaterally into the hippocampus 15 min before gating measurements. RESULTS Systemic injection of CGP56999A, at a dose of 0.2 and 0.4 mg/kg i.p. resulted in reduced gating of hippocampal AEP in a dose-dependent manner. Reduced gating was found at conditioning-test interpulse intervals of 300-500 ms, but not 100-200 ms. Reduced gating of hippocampal AEP also followed bilateral infusion of CGP56999A into the hippocampus (0.1 μg/μL/side). Gating loss was attributed to a decreased conditioning response and an increased test response after systemic or local injection of CGP56999A. Robust PPI was found at prepulse-pulse intervals of 30-100 ms, and this PPI was reduced by hippocampal infusion of CGP56999A in a dose-dependent manner, as compared with saline infusion. CONCLUSIONS Blockade of hippocampal GABA(B) receptors led to deficits in sensory and sensorimotor gating, which are symptoms of schizophrenia.
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25
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Ma J, Tai SK, Leung LS. Ketamine-induced deficit of auditory gating in the hippocampus of rats is alleviated by medial septal inactivation and antipsychotic drugs. Psychopharmacology (Berl) 2009; 206:457-67. [PMID: 19655127 DOI: 10.1007/s00213-009-1623-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Accepted: 07/12/2009] [Indexed: 10/20/2022]
Abstract
RATIONALE Gating of sensory responses is impaired in schizophrenic patients and animal models of schizophrenia. Ketamine, an N-methyl-D-aspartate receptor antagonist, is known to induce schizophrenic-like symptoms including sensory gating deficits in humans. OBJECTIVE This study aims to investigate the mechanisms underlying ketamine's effect on gating of auditory evoked potentials in the hippocampus of freely moving rats. METHODS Gating was measured by the ratio of the test-click response (T) to the conditioning-click response (C), or T/C, with T and C measured as peak amplitudes. RESULTS Ketamine (1, 3, or 6 mg/kg s.c.) injection dose-dependently increased T/C ratio as compared to saline injection (s.c.). T/C ratio was 0.48 +/- 0.05 after saline injection and 0.73 +/- 0.17 after ketamine (3 mg/kg s.c.) injection. The increase in T/C ratio after ketamine was blocked by prior inactivation of the medial septum with GABA(A) receptor agonist muscimol or by systemic administration of antipsychotic drugs, including chlorpromazine (5 mg/kg i.p.), haloperidol (1 mg/kg i.p.), or clozapine (7.5 mg/kg i.p.). Infusion of muscimol into the medial septum or injection of an antipsychotic drug alone did not affect the T/C ratio. However, rats with selective lesion of the septohippocampal cholinergic neurons by 192 IgG-saporin showed a significantly higher T/C ratio (0.86 +/- 0.10) than sham lesion rats (0.26 +/- 0.07), and ketamine did not further increase T/C ratio in rats with septohippocampal cholinergic neuron lesion. CONCLUSIONS Ketamine's disruption of hippocampal auditory gating was normalized by inactivation of the medial septum; in addition, septal cholinergic neurons participate in normal auditory gating.
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Affiliation(s)
- Jingyi Ma
- Department of Physiology and Pharmacology, Medical Sciences Building, The University of Western Ontario, London, ON, Canada N6A 5C1.
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26
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Abstract
Central sensory filtering processes can be demonstrated using a paired stimulus paradigm. Normal humans show a diminished, vertex-recorded mid-latency (50 ms) of auditory evoked potential to the second of paired clicks (0.5 s apart), a phenomenon termed as auditory gating. A loss of 50 ms in auditory gating is strongly related to psychosis. The N40 auditory evoked potential (EP) in rats has been used to develop an animal model for the study of sensory gating mechanisms. Previous animal studies of auditory gating have used psychotomimetic drug administration to induce sensory gating. However, a nonpharmacologic model of deficient gating would be advantageous. In the present study we investigated the effect of immobilization stress on sensory gating in twelve adult male mice. Evoked responses to the paired auditory click stimuli from vertex location of scalp were recorded using a silver needle electrode, a bioelectric amplifier, and an analog-digital converter. The mice were exposed to immobilization stress (IS) for 3 h. Data showed that the N40 potential was depressed in response to the second of the paired stimuli before application immobilization stress. At the end of the 3-h immobilization, the depression of the second N40 response was not observed. It was concluded that sensory gating is present in the mice and acutely disrupted by stressful stimuli, as shown in human subjects and rats.
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Affiliation(s)
- Cem Süer
- University of Erciyes, Faculty of Medicine, Department of Physiology, 38039 Kayseri, Turkey
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Knott V, Millar A, Fisher D. Sensory gating and source analysis of the auditory P50 in low and high suppressors. Neuroimage 2009; 44:992-1000. [DOI: 10.1016/j.neuroimage.2008.10.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/24/2008] [Accepted: 10/06/2008] [Indexed: 10/21/2022] Open
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Dissanayake DWN, Zachariou M, Marsden CA, Mason R. Auditory gating in rat hippocampus and medial prefrontal cortex: effect of the cannabinoid agonist WIN55,212-2. Neuropharmacology 2008; 55:1397-404. [PMID: 18809420 DOI: 10.1016/j.neuropharm.2008.08.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 06/25/2008] [Accepted: 08/28/2008] [Indexed: 10/21/2022]
Abstract
Sensory gating can be assessed in rodents and humans using an auditory conditioning (C)-test (T) paradigm, with schizophrenic patients exhibiting a loss of gating. Dysregulation of the endocannabinoid system has been proposed to be involved in the pathogenesis of schizophrenia. We studied auditory gating and the effects of the cannabinoid agonist WIN55,212-22 on gating in CA3 and dentate gyrus (DG) of the hippocampus and medial prefrontal cortex (mPFC) in male Lister hooded rats using in vivo electrophysiology. The effects of a single dose of WIN55,212-2 on the N2 local field potential (LFP) test/conditioning amplitude ratios (T/C ratio) and response latencies were examined. In rats that demonstrated gating of N2, mPFC showed higher T/C ratios and shorter conditioning response latencies compared to DG and CA3. WIN55,212-2 disrupted auditory gating in all three areas with a significant increase in test amplitudes in the gating rats. A group of non-gating rats demonstrated higher test amplitudes and higher T/C ratios compared to gating rats. WIN55,212-2 had no effect on T/C ratios in the non-gating rats. The cannabinoid receptor (CB1) antagonist SR141716A prevented WIN55,212-2 induced disruption of gating. This study demonstrates gated auditory-evoked responses in CA3, DG and mPFC. The mPFC showed an early phase of gating which may later be modulated by CA3 and DG activity. Furthermore, cannabinoid receptor activation disrupted auditory gating in CA3, DG and mPFC, an effect which was prevented by CB1 receptor antagonism. The results further demonstrate the presence of a non-gating rat population which responded differently to cannabinoid agonists.
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Affiliation(s)
- Dilshani W N Dissanayake
- School of Biomedical Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, Nottinghamshire NG7 2UH, UK.
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Stevens KE, Adams CE, Mellott TJ, Robbins E, Kisley MA. Perinatal choline deficiency produces abnormal sensory inhibition in Sprague-Dawley rats. Brain Res 2008; 1237:84-90. [PMID: 18778692 DOI: 10.1016/j.brainres.2008.08.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 08/14/2008] [Accepted: 08/15/2008] [Indexed: 10/21/2022]
Abstract
Adequate choline levels in rodents during gestation have been shown to be critical to several functions, including certain learning and memory functions, when tested at adulthood. Choline is a selective agonist for the alpha7 nicotinic receptor which appears in development before acetylcholine is present. Normal sensory inhibition is dependent, in part, upon sufficient numbers of this receptor in the hippocampus. The present study assessed sensory inhibition in Sprague-Dawley rats gestated on normal (1.1 g/kg), deficient (0 g/kg) or supplemented (5 g/kg) choline in the maternal diet during the critical period for cholinergic cell development (E12-18). Rats gestated on deficient choline showed abnormal sensory inhibition when tested at adulthood, while rats gestated on normal or supplemented choline showed normal sensory inhibition. Assessment of hippocampal alpha-bungarotoxin to visualize nicotinic alpha7 receptors revealed no difference between the gestational choline levels. These data suggest that attention to maternal choline levels for human pregnancy may be important to the normal functioning of the offspring.
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Affiliation(s)
- Karen E Stevens
- Medical Research Service, Department of Veterans Affairs Medical Center, Denver, CO, USA.
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Tregellas JR, Davalos DB, Rojas DC, Waldo MC, Gibson L, Wylie K, Du YP, Freedman R. Increased hemodynamic response in the hippocampus, thalamus and prefrontal cortex during abnormal sensory gating in schizophrenia. Schizophr Res 2007; 92:262-72. [PMID: 17336502 PMCID: PMC2726714 DOI: 10.1016/j.schres.2006.12.033] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 12/11/2006] [Accepted: 12/14/2006] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Deficits in sensory gating are a common feature of schizophrenia. Failure of inhibitory gating mechanisms, shown by poor suppression of evoked responses to repeated auditory stimuli, has been previously studied using EEG methods. These methods yield information about the temporal characteristics of sensory gating deficits, but do not identify brain regions involved in the process. Hence, the neuroanatomical substrates of poor sensory gating in schizophrenia remain largely unknown. This study used functional magnetic resonance imaging (fMRI) to investigate the functional neuroanatomy of sensory gating deficits in schizophrenia. METHODS Twelve patients with schizophrenia and 12 healthy comparison subjects were scanned at 3 Tesla while performing a sensory gating task developed for fMRI. P50 EEG evoked potential recordings from a paired-stimulus conditioning-test paradigm were obtained from the same subjects. RESULTS Compared to healthy comparison subjects, patients with schizophrenia exhibited greater activation in the hippocampus, thalamus, and dorsolateral prefrontal cortex (DLPFC) during the fMRI sensory gating task. No group difference was observed in the superior temporal gyrus. Schizophrenia subjects also showed decreased P50 suppression as measured with EEG. Hemodynamic response in the fMRI measure was positively correlated with test/conditioning ratios from the EEG sensory gating measure. CONCLUSIONS Poor sensory gating in schizophrenia is associated with dysfunction of an apparent network of brain regions, including the hippocampus, thalamus and DLPFC. Greater activation of these regions is consistent with evidence for diminished inhibitory function in schizophrenia.
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Cromwell HC, Klein A, Mears RP. Single unit and population responses during inhibitory gating of striatal activity in freely moving rats. Neuroscience 2007; 146:69-85. [PMID: 17321056 PMCID: PMC4127048 DOI: 10.1016/j.neuroscience.2007.01.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 12/29/2006] [Accepted: 01/13/2007] [Indexed: 10/23/2022]
Abstract
The striatum is thought to be an essential region for integrating diverse information in the brain. Rapid inhibitory gating (IG) of sensory input is most likely an early factor necessary for appropriate integration to be completed. Gating is currently evaluated in clinical settings and is dramatically altered in a variety of psychiatric illnesses. Basic neuroscience research using animals has revealed specific neural sites involved in IG including the hippocampus, thalamus, brainstem, amygdala and medial prefrontal cortex. The present study investigated local IG in the basal ganglia structure of the striatum using chronic recording microwires. We obtained both single unit activations and local field potentials (LFPs) in awake behaving rats from each wire during the standard two-tone paradigm. Single units responded with different types of activations including a phasic and sustained excitation, an inhibitory response and a combination response that contained both excitatory and inhibitory components. IG was observed in all the response types; however, non-gating was observed in a large proportion of responses as well. Positive wave field potentials at 50-60 ms post-stimulus (P60) showed consistent gating across the wire arrays. No significant correlations were found between single unit and LFP measures of gating during the initial baseline session. Gating was strengthened (Tamp/Camp ratios approaching 0) following acute stress (saline injection) at both the single unit and LFP level due to the reduction in the response to the second tone. Alterations in sensory responding reflected by changes in the neural response to the initial tone were primarily observed following long-term internal state deviation (food deprivation) and during general locomotion. Overall, our results support local IG by single neurons in striatum but also suggest that rapid inhibition is not the dominant activation profile observed in other brain regions.
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Affiliation(s)
- H C Cromwell
- Department of Psychology and The J. P. Scott Center for Neuroscience, Mind and Behavior at Bowling Green State University, Psychology Building, Bowling Green, OH 43403, USA.
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Cromwell HC, Woodward DJ. Inhibitory gating of single unit activity in amygdala: effects of ketamine, haloperidol, or nicotine. Biol Psychiatry 2007; 61:880-9. [PMID: 17054921 DOI: 10.1016/j.biopsych.2006.06.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 05/26/2006] [Accepted: 06/27/2006] [Indexed: 11/18/2022]
Abstract
BACKGROUND Inhibitory gating is thought to be a basic process for filtering incoming stimuli to the brain. Little information is currently available concerning local neural networks of inhibitory gating or the intrinsic neurochemical substrates involved in the process. METHODS The goal of the present study was to examine the pharmacological aspects of inhibitory gating from single units in the amygdala. We tested the effects of ketamine (80 mg/kg) and haloperidol (1 mg/kg) on inhibitory gating. Additionally, we examined the effect of nicotine (1.2 mg/kg) on single unit gating in this same brain structure. RESULTS We found that in one subset of neurons, ketamine administration significantly reduced tone responsiveness with a subsequent loss of inhibitory gating, whereas the other subset persisted in both auditory responding and gating albeit at a weaker level. Haloperidol and nicotine had very similar effects, exemplified by a dramatic increase in the response to the initial "conditioning" tone with a subsequent improvement in inhibitory gating. CONCLUSIONS Tone responsiveness and inhibitory gating persists in a subset of neurons after glutamate N-methyl-D-aspartate receptor blockade. Dopamine and nicotine modulate gating in these normal animals and have similar effects of enhancing responsiveness to auditory stimulation at the single unit and evoked potential level.
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Affiliation(s)
- Howard C Cromwell
- Department of Physiology and Pharmacology, School of Medicine, Wake Forest University, Winston-Salem, North Carolina, USA.
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Turetsky BI, Calkins ME, Light GA, Olincy A, Radant AD, Swerdlow NR. Neurophysiological endophenotypes of schizophrenia: the viability of selected candidate measures. Schizophr Bull 2007; 33:69-94. [PMID: 17135482 PMCID: PMC2632291 DOI: 10.1093/schbul/sbl060] [Citation(s) in RCA: 415] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In an effort to reveal susceptibility genes, schizophrenia research has turned to the endophenotype strategy. Endophenotypes are characteristics that reflect the actions of genes predisposing an individual to a disorder, even in the absence of diagnosable pathology. Individual endophenotypes are presumably determined by fewer genes than the more complex phenotype of schizophrenia and would, therefore, reduce the complexity of genetic analyses. Unfortunately, despite there being rational criteria to define a viable endophenotype, the term is sometimes applied indiscriminately to characteristics that are deviant in affected individuals. Schizophrenia patients exhibit deficits in several neurophysiological measures of information processing that have been proposed as candidate endophenotypes. Successful processing of sensory inputs requires the ability to inhibit intrinsic responses to redundant stimuli and, reciprocally, to facilitate responses to less frequent salient stimuli. There is evidence to suggest that both these processes are "impaired" in schizophrenia. Measures of inhibitory failure include prepulse inhibition of the startle reflex, P50 auditory evoked potential suppression, and antisaccade eye movements. Measures of impaired deviance detection include mismatch negativity and the P300 event-related potential. The purpose of this review is to systematically evaluate the endophenotype candidacy of these key neurophysiological abilities. For each candidate, we describe typical experimental procedures, the current understanding of the underlying neurobiology, the nature of the abnormality in schizophrenia, the reliability, stability and heritability of the measure, and any reported gene associations. We conclude with a discussion of the few studies thus far that have employed a multivariate approach with these candidates.
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Affiliation(s)
- Bruce I Turetsky
- Department of Psychiatry, 10th floor, Gates Building, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA.
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Stevens KE, O'Neill HC, Rose GM, Luthman J. The 5-HT1A receptor active compounds (R)-8-OH-DPAT and (S)-UH-301 modulate auditory evoked EEG responses in rats. Amino Acids 2006; 31:365-75. [PMID: 16868646 DOI: 10.1007/s00726-006-0374-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2005] [Accepted: 03/01/2006] [Indexed: 11/25/2022]
Abstract
Schizophrenics commonly demonstrate abnormalities in central filtering capability following repetitive sensory stimuli. Such sensory inhibition deficits can be mirrored in rodents following administration of psycho-stimulatory drugs. In the present study, male Sprague-Dawley rats were implanted with brain surface electrodes to record auditory evoked EEG potentials in a paired-stimulus paradigm, using 87 dB clicks delivered 0.5 s apart. Amphetamine (1.83 mg/kg, i.p.) produced the expected loss of sensory inhibition, as defined by an increase in the ratio between test (T) and conditioning (C) amplitudes at N40, a mid-latency peak of the evoked potentials. Also, the 5-HT(1A) agonist (R)-8-OH-DPAT caused a significant increase in the TC ratio at the highest dose studied (0.5 mg/kg s.c.), while the 5-HT(1A) antagonist (S)-UH-301 did not significantly affect the TC ratio at any dose studied (0.1-5 mg/kg s.c.). When administered with amphetamine, a lower dose of 8-OH-DPAT (0.1 mg/kg) and the highest dose of UH-301 tested (5 mg/kg, s.c.) were able to reverse the amphetamine-induced increase in TC ratio. The findings suggest that 5-HT(1A) signaling is involved in sensory inhibition and support the evaluation of 5-HT(1A) receptor active compounds in conditions with central filtering deficits, such as schizophrenia.
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Affiliation(s)
- K E Stevens
- Medical Research, VA Medical Center, Denver, CO, USA
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Radek RJ, Miner HM, Bratcher NA, Decker MW, Gopalakrishnan M, Bitner RS. Alpha4beta2 nicotinic receptor stimulation contributes to the effects of nicotine in the DBA/2 mouse model of sensory gating. Psychopharmacology (Berl) 2006; 187:47-55. [PMID: 16767415 DOI: 10.1007/s00213-006-0394-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Accepted: 03/22/2006] [Indexed: 10/24/2022]
Abstract
RATIONALE Nicotine improves the deficiencies of sensory gating function in schizophrenic patients and in dilute brown non-Agouti (DBA/2) mice. This effect of nicotine has been attributed to activation of the alpha7 nicotinic acetylcholine receptor (nAChR) subtype. OBJECTIVE The aim of this study was to determine whether the activation of another nAChR subtype, the central nervous system (CNS) prominent alpha4beta2 receptor, also contributes to the effects of nicotine on sensory gating in DBA/2 mice. METHODS Unanesthetized DBA/2 mice were treated either with nicotine, the alpha4beta2 antagonist dihydro-beta-erythroidine, the noncompetitive nAChR antagonist mecamylamine, or a combination of an antagonist and nicotine. Thereafter, gating was assessed by recording hippocampal evoked potentials (EP), which were elicited by pairs of auditory clicks. The EP response to the second click, or test amplitude (TAMP), was divided by the EP response to the first click, or condition amplitude (CAMP), to derive gating T:C ratios. RESULTS Nicotine significantly (p<0.05) lowered T:C ratios by 42%, while significantly increasing CAMP by 55%. After a pretreatment with dihydro-beta-erythroidine, nicotine still significantly lowered T:C ratios by 28%; however, the nicotine-induced increase of CAMP was blocked. Mecamylamine blocked the effect of nicotine on both T:C ratios and CAMP. CONCLUSIONS Activation of alpha4beta2 receptors by nicotine increases CAMP. However, under conditions where alpha4beta2 receptors are blocked, nicotine still lowers T:C ratios and may improve sensory gating, possibly through the activation of other nAChR subtypes such as alpha7. These effects of nicotine on auditory EPs may be indicative of a profile that would improve information processing in schizophrenia and other CNS diseases.
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Affiliation(s)
- Richard J Radek
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Dept. R4N5, AP9A/LL, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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Boutros NN, Trautner P, Rosburg T, Korzyukov O, Grunwald T, Schaller C, Elger CE, Kurthen M. Sensory gating in the human hippocampal and rhinal regions. Clin Neurophysiol 2005; 116:1967-74. [PMID: 16000257 DOI: 10.1016/j.clinph.2005.04.017] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Revised: 03/21/2005] [Accepted: 04/08/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The objective of this work was to ascertain if sensory gating can be demonstrated within the human medial temporal lobe. METHODS Eight patients with intractable epilepsy with depth electrodes implanted in the medial temporal lobe for pre-surgery evaluation underwent evoked response recording to auditory paired-stimuli (S1-S2). Each of the eight subjects had a diagnosis of left medial temporal lobe epilepsy (MTLE). RESULTS Data from the non-focal right hippocampi revealed a large negative response on S1 (starting at about 190 ms and lasting for approximately 300 ms from stimulus onset). Rhinal region recordings revealed a positive response (starting at about 240 ms with a rapid incline, followed by a long-lasting decline). A significant attenuation of both responses to S2 stimuli was observed. CONCLUSIONS Data are suggestive of an involvement of the human medial temporal lobe in the processing of simple auditory information which occurs in a time frame later than the neocortical auditory evoked components. The exact role of these anatomical structures in the sensory gating process remains to be defined. SIGNIFICANCE This study provides the first evidence of an activation of the rhinal cortex after simple auditory stimulation and provides new evidence that the activation of the medial temporal lobe structures occurs at a later stage than that of the neocortex.
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Affiliation(s)
- N N Boutros
- Wayne State University School of Medicine, Department of Psychiatry and Behavioral Neurosciences, School of Medicine, UPC-Jefferson, 2751 E Jefferson, Suite 401, Detroit, MI 48207, USA.
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Shepard PD, Joy B, Clerkin L, Schwarcz R. Micromolar brain levels of kynurenic acid are associated with a disruption of auditory sensory gating in the rat. Neuropsychopharmacology 2003; 28:1454-62. [PMID: 12700696 DOI: 10.1038/sj.npp.1300188] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Brain levels of kynurenic acid (KYNA), an endogenous antagonist of glycine(B)/NMDA and alpha-7 nicotinic acetylcholine receptors, are elevated in individuals with schizophrenia. Both receptors are broadly implicated in the pathophysiology of this disease, particularly in the deficits many patients show in filtering the sensorium. In the present study, we sought to determine whether elevated brain levels of KYNA disrupt auditory gating in anesthetized rats. A mid-latency evoked potential was recorded from the hippocampus in response to a pair of auditory tones. Gating was assessed by determining the ratio of the amplitude of test and conditioning responses (T/C ratio) in rats that had received KYNA's precursor L-kynurenine (KYN; 150 mg/kg, i.p.) together with probenecid (PBCD; 200 mg/kg, i.p.) 2 h prior to the start of the recording session. KYNA levels in the hippocampus of KYN+PBCD-treated rats were increased 500-fold, and accompanied by a significant increase in T/C ratio consistent with a disruption in sensory gating. PBCD alone increased hippocampal KYNA 12-fold, but did not significantly elevate T/C ratio. L-701,324 (3-30 mg/kg, i.v.), a centrally acting glycine(B) site antagonist, also failed to disrupt gating; however, large quantities of the competitive NMDA receptor antagonist DL-2-amino-5-phosphopentanoate (200 nmol, i.c.v.) markedly increased T/C ratio. Thus, while total blockade of NMDA receptors disrupts auditory gating, partial blockade achieved by antagonism of its glycine coagonist binding site does not. These observations indicate that the disruption in auditory processing in rats with greatly elevated KYNA levels is not attributable to the compound's antagonist actions at the glycine(B) receptor.
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Affiliation(s)
- Paul D Shepard
- Maryland Psychiatric Research Center, Department of Psychiatry, University of Maryland School of Medicine, PO Box 21247, Baltimore, MD 21228, USA.
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Freedman R, Adams CE, Adler LE, Bickford PC, Gault J, Harris JG, Nagamoto HT, Olincy A, Ross RG, Stevens KE, Waldo M, Leonard S. Inhibitory neurophysiological deficit as a phenotype for genetic investigation of schizophrenia. AMERICAN JOURNAL OF MEDICAL GENETICS 2003; 97:58-64. [PMID: 10813805 DOI: 10.1002/(sici)1096-8628(200021)97:1<58::aid-ajmg8>3.0.co;2-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many investigators have proposed that biological endophenotypes might facilitate the genetic analysis of schizophrenia. A deficit in the inhibition of the P50 evoked response to repeated auditory stimuli has been characterized as a neurobiological deficit in schizophrenia. This deficit is linked to a candidate gene locus, the locus of the alpha7-nicotinic cholinergic receptor subunit gene on chromosome 15q14. Supportive evidence has been found by other investigators, including: 1) linkage of schizophrenia to the same locus; 2) linkage of bipolar disorder to the locus; and 3) replication of the existence of this neurobiological deficit and its relation to broader neuropsychological deficits in schizophrenia. It is certain that there are many genetic factors in schizophrenia and bipolar disorder; what is needed is a complete and precise description of the contribution of each individual factor to the pathophysiology of these illnesses.
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Affiliation(s)
- R Freedman
- Psychiatry and Pharmacology, University of Colorado, CO 80262, USA.
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Krause M, Hoffmann WE, Hajós M. Auditory sensory gating in hippocampus and reticular thalamic neurons in anesthetized rats. Biol Psychiatry 2003; 53:244-53. [PMID: 12559658 DOI: 10.1016/s0006-3223(02)01463-4] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND Auditory gating is thought to reflect sensory information processing and is absent or diminished in schizophrenic patients. Although abnormal thalamic sensory processing has been proposed in schizophrenia, sensory gating of thalamic neurons has not been demonstrated experimentally. The aim of the present study was to establish whether auditory gating is present in the rat thalamus using a well-characterized animal model of auditory gating and schizophrenia. METHODS Hippocampal electroencephalogram and single-unit activity in the thalamic reticular nucleus (nRT) were recorded in anaesthetized rats. Evoked potentials in the hippocampus and neuronal activity in the nRT were monitored in response to bilateral auditory stimuli. The effects of the psychostimulant D-amphetamine and the antipsychotic haloperidol on auditory gating were evaluated. RESULTS Thalamic reticular nucleus neurons showed gated responses to paired-tone auditory stimuli, resembling hippocampal auditory gating. D-amphetamine disrupted auditory gating of nRT neurons and abolished their burst activity. D-amphetamine also disrupted hippocampal auditory gating and induced hippocampal theta activity. The amphetamine-induced gating deficit was reversed by haloperidol in both regions. CONCLUSIONS Our findings provide the first experimental evidence for auditory gating of nRT neurons. We demonstrated that amphetamine disrupts sensory processing of nRT neurons, indicating similarities between hippocampal and thalamic sensory gating. These findings support the presumed connection between dopamine hyperfunction and abnormal thalamic filtering in schizophrenia.
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Affiliation(s)
- Michael Krause
- Pharmacia Corporation, Neurobiology, 301 Henrietta Street, Kalamazoo, Michigan 49007, USA
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Buhler AV, Dunwiddie TV. Regulation of the activity of hippocampal stratum oriens interneurons by alpha7 nicotinic acetylcholine receptors. Neuroscience 2002; 106:55-67. [PMID: 11564416 DOI: 10.1016/s0306-4522(01)00257-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
GABAergic interneurons have been shown to be a major target of cholinergic inputs to the hippocampus. Because these interneurons project to pyramidal neurons as well as other interneurons, activation of the cholinergic system is likely to produce a complex modulation of local inhibitory activity. To better understand the role of post-synaptic alpha7 nicotinic acetylcholine receptors in the hippocampus, we have characterized the effects of nicotinic agents on local interneurons of the rat CA1 stratum oriens in terms of activation, desensitization, and region of axonal termination. Fast application of acetylcholine onto stratum oriens interneurons during whole-cell recordings from hippocampal slices activated the majority of cells tested, and these responses were mediated almost entirely by alpha7 nicotinic acetylcholine receptors. Anatomical reconstructions showed no clear relationship between the acetylcholine responsivity of interneurons and the regions to which their axons project. Currents mediated by alpha7 receptors declined markedly during repetitive activation in the theta rhythm range (4-12 Hz) when activated by either pressure application or synaptic release of acetylcholine. However, the decay of alpha7 receptor-mediated currents was unaffected by treatment with the cholinesterase inhibitor neostigmine (10 nM-10 microM), suggesting that hydrolysis of acetylcholine is not a rate-limiting step in the termination of these responses. From these findings we suggest that nicotinic receptor activity in this region has an extensive and complex impact on local inhibitory circuits that is mediated by activation of several classes of intrinsic GABAergic cells. In addition, desensitization of the alpha7 nicotinic acetylcholine receptor is likely to contribute to the decay of individual responses to pressure application of agonist, and may also act in a cumulative fashion to impair the ability of these receptors to support repetitive activity during trains of activation. If applicable to alpha7 receptor responses in vivo, we suggest it may be difficult to enhance these responses for therapeutic purposes with cholinesterase inhibitors.
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Affiliation(s)
- A V Buhler
- Department of Pharmacology, University of Colorado Health Sciences Center, 4200 East 9th Avenue, Denver, CO 80262, USA.
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Abstract
Sensory gating is defined as a decreased reaction on the second click, measured as evoked potentials (EP) within a double click paradigm. Recently, it was established that gating in rats was decreased during REM sleep compared to wakefulness and non-REM sleep. REM sleep in the rat is characterized by hippocampal theta rhythm. Therefore, it was investigated whether sensory gating would also be diminished during other states with hippocampal theta. Twelve Wistar rats were implanted with hippocampal electrodes and exposed to double clicks during passive wakefulness, REM sleep, and activity (voluntary movements and walking on a moving belt). Gating was examined by use of the amplitudes of the EPs in reaction to the first conditioned amplitude (CAMP) and second click test amplitude (TAMP), as well as two gating parameters (C-T score and T/C ratio). Except passive wakefulness all behavioral conditions were accompanied by hippocampal theta. Normal gating was always found, except during REM sleep. The CAMP was than lower than during passive wakefulness. Gating was less disturbed during behavioral activity. Negative correlations were found between the percentage theta power on the one side and the CAMP, respectively, the C-T score, on the other. The correlation between the percentage theta power and the T/C ratio was also significant. It is concluded that the presence of hippocampal theta is not a sufficient condition to cause disturbances in auditory sensory gating. Behavioral states that accompany theta activity, however, tend to affect the CAMP. The decrease in gating found during REM sleep cannot be easily related to well-known neurochemical and pharmacological data.
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Affiliation(s)
- U Schridde
- NICI, Department of Comparative and Physiological Psychology, University of Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, Netherlands
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van Luijtelaar G, Fabene PF, de Bruin N, Jongema C, Ellenbroek BA, Veening JG. Neural correlates of sensory gating in the rat: decreased Fos induction in the lateral septum. Brain Res Bull 2001; 54:145-51. [PMID: 11275403 DOI: 10.1016/s0361-9230(00)00430-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the P(50) gating or conditioning-testing paradigm in the rat, two identical click stimuli are presented with an inter-click interval of 500 ms. The reaction towards the second click, as measured with evoked potentials, is reduced in respect to that towards the first click; this phenomenon is called sensory gating. In the present experiments, the inter-click interval was varied systematically and auditory evoked potentials were measured. Sensory gating was found to occur only at intervals between 500 and 1000 ms, but not at longer intervals. Fos immunohistochemistry was then performed using two groups of rats exposed to double clicks: the inter-click interval was 500 ms in the experimental group and 2500 ms in the control group. Fos induction was analyzed in selected brain structures. In the auditory pathways, Fos-immunoreactive neurons were found in both groups of rats in the inferior colliculus and medial geniculate body. Fos-immunoreactive cells were also examined in the septum and hippocampus. In the ventral part of the lateral septal nucleus, the labeled neurons were significantly fewer in the experimental animals compared to the control group. Smaller and non-significant quantitative differences of Fos-positive neurons were documented in the medial septum and hippocampal CA1 region. These data point out a selective decrease in the lateral septum of Fos induced by auditory sensory gating, and suggest an involvement of this structure, and possibly of other parts of the septo-hippocampal system, in sensory gating mechanisms. The results might be relevant for theories on sensory gating deficits in schizophrenia.
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Affiliation(s)
- G van Luijtelaar
- NICI, Department of Psychology, University of Nijmegen, Nijmegen, The Netherlands.
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43
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Leonard S, Breese C, Adams C, Benhammou K, Gault J, Stevens K, Lee M, Adler L, Olincy A, Ross R, Freedman R. Smoking and schizophrenia: abnormal nicotinic receptor expression. Eur J Pharmacol 2000; 393:237-42. [PMID: 10771019 DOI: 10.1016/s0014-2999(00)00035-2] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Biological and genetic evidence suggests a role for the neuronal nicotinic receptors in the neuropathophysiology of schizophrenia. Nicotine normalizes an auditory evoked potential deficit seen in subjects who suffer from the disease. Nicotinic receptors with both high and low affinity for nicotine are decreased in postmortem brain of schizophrenics compared to control subjects. The chromosomal locus of the human alpha-7 gene (15q14) is linked to the gating deficit with a lod of 5.3, and antagonists of the alpha-7 receptor (alpha-bungarotoxin and methyllycaconitine) induce a loss of gating in rodents. We have cloned the human alpha-7 gene and found it to be partially duplicated proximal to the full-length gene. The duplication is expressed in both the brain and in peripheral blood cells of normal subjects, but is missing in some schizophrenic subjects. The results of these studies suggest the presence of abnormal expression and function of the neuronal nicotinic receptor gene family in schizophrenia.
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Affiliation(s)
- S Leonard
- Department of Psychiatry, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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44
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Opioids suppress IPSCs in neurons of the rat medial septum/diagonal band of Broca: involvement of mu-opioid receptors and septohippocampal GABAergic neurons. J Neurosci 2000. [PMID: 10648722 DOI: 10.1523/jneurosci.20-03-01179.2000] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The medial septum/diagonal band region (MSDB), which provides a major cholinergic and GABAergic input to the hippocampus, expresses a high density of opioid receptors. Behaviorally, intraseptal injections of opioids produce deficits in spatial memory, however, little is known about the electrophysiological effects of opioids on MSDB neurons. Therefore, we investigated the electrophysiological effects of opioids on neurons of the MSDB using rat brain slices. In voltage-clamp recordings with patch electrodes, bath-applied met-enkephalin, a nonselective opioid receptor agonist, decreased the number of tetrodotoxin and bicuculline-sensitive inhibitory synaptic currents in cholinergic- and GABA-type MSDB neurons. A similar effect occurred in brain slices containing only the MSDB, suggesting that opioids decrease GABA release primarily by inhibiting spontaneously firing GABAergic neurons located within the MSDB. Accordingly, in extracellular recordings, opioid-sensitive, spontaneously firing neurons could be found within the MSDB. Additionally, in intracellular recordings a subpopulation of GABA-type neurons were directly inhibited by opioids. All effects of met-enkephalin were mimicked by a mu receptor agonist, but not by delta or kappa agonists. In antidromic activation studies, mu-opioids inhibited a subpopulation of septohippocampal neurons with high conduction velocity fibers, suggestive of thickly myelinated GABAergic fibers. Consistent with the electrophysiological findings, in double-immunolabeling studies, 20% of parvalbumin-containing septohippocampal GABA neurons colocalized the mu receptor, which at the ultrastructural level, was found to be associated with the neuronal cell membrane. Thus, opioids, via mu receptors, inhibit a subpopulation of MSDB GABAergic neurons that not only make local connections with both cholinergic and noncholinergic-type MSDB neurons, but also project to the hippocampus.
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45
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Miyazato H, Skinner RD, Garcia-Rill E. Neurochemical modulation of the P13 midlatency auditory evoked potential in the rat. Neuroscience 1999; 92:911-20. [PMID: 10426532 DOI: 10.1016/s0306-4522(98)00762-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Previous studies have shown that the vertex-recorded P13 auditory evoked potential in the rat appears to be the rodent equivalent of the human P1 (or P50) potential. This sleep state-dependent potential appears to be generated, at least in part, by cholinergic pedunculopontine nucleus projections. The present studies used localized microinjections of neuroactive compounds into the region of the pedunculopontine nucleus in order to modulate the vertex-recorded P13 potential. Both the GABAergic agonist, muscimol, and the noradrenergic alpha2 receptor agonist, clonidine, were found to reduce the amplitude of the P13 potential in a dose-dependent manner. The suppressive effect of clonidine on P13 potential amplitude was blocked by pretreatment with the noradrenergic alpha2 receptor antagonist, yohimbine. In addition, habituation of the P13 potential, measured using a paired stimulus paradigm, was increased by micro-injection of a dose of muscimol or clonidine which did not change the amplitude of the P13 potential induced by the first stimulus of a pair. In contrast, microinjection of yohimbine decreased habituation of the P13 potential. These results show that the vertex-recorded P13 potential and its habituation can be modulated by activation of known inhibitory synapses, both GABAergic and noradrenergic, at the level of the pedunculopontine nucleus. This provides further evidence that the P13 potential is generated, at least in part, by pedunculopontine nucleus outputs.
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Affiliation(s)
- H Miyazato
- Department of Anatomy, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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46
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Moxon KA, Gerhardt GA, Bickford PC, Austin K, Rose GM, Woodward DJ, Adler LE. Multiple single units and population responses during inhibitory gating of hippocampal auditory response in freely-moving rats. Brain Res 1999; 825:75-85. [PMID: 10216175 DOI: 10.1016/s0006-8993(99)01187-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Paired clicks were presented to awake, freely-moving rats to examine neuronal activity associated with inhibitory gating of responses to repeated auditory stimuli. The rats had bundles of eight microwires implanted into each of four different brain areas: CA3 region of the hippocampus, medial septal nucleus, brainstem reticular nucleus, and the auditory cortex. Single-unit recordings from each wire were made while the local auditory-evoked potential was also recorded. The response to a conditioning stimulus was compared to the response to a test stimulus delivered 500 ms later: the ratio of the test response to the conditioning response provided a measure of inhibitory gating. Auditory-evoked potentials were recorded at all sites. Overall, brainstem reticular nucleus neurons showed the greatest gating of local auditory-evoked potentials, while the auditory cortex showed the least. However, except for the auditory cortex, both gating and non-gating of the evoked response were recorded at various times in all brain regions. Gating of the hippocampal response was significantly correlated with gating in the medial septal nucleus and brainstem reticular nucleus, but not the auditory cortex. Single-unit neuron firing in response to the clicks was most pronounced in the brainstem reticular nucleus and the medial septal nucleus, while relatively few neurons responded in the CA3 region of the hippocampus and the auditory cortex. Taken together, these data support the hypothesis that inhibitory gating of the auditory-evoked response originates in the non-lemniscal pathway and not in cortical areas of the rat brain.
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Affiliation(s)
- K A Moxon
- Department of Neurobiology and Anatomy, MCP Hahnemann University, 3200 Henry Avenue, Philadelphia, PA 19129, USA.
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47
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Liu W, Kumar A, Alreja M. Excitatory effects of muscarine on septohippocampal neurons: involvement of M3 receptors. Brain Res 1998; 805:220-33. [PMID: 9733970 DOI: 10.1016/s0006-8993(98)00729-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Cholinergic mechanisms in the septohippocampal pathway contribute to several cognitive functions and impaired cholinergic transmission in this pathway may be related to the memory loss and dementia that accompanies normal aging and Alzheimer's disease and behavioral studies suggest that muscarinic mechanisms in the medial septum/diagonal band of Broca (MSDB) may contribute to these functions. The goal of the present study was to begin a characterization of the physiological and pharmacological effects of muscarine on antidromically identified septohippocampal neurons (SHNs). Muscarinic agonists produced a concentration-dependent excitation in >90% of SHNs tested using extracellular recordings in an in vitro rat brain slice preparation. The SHNs excited by muscarine had a broad range of conduction velocities (0.2 to 3.7 m/s; mean: 1.6+/-0.06 m/s; n=110), suggesting involvement of neurons with both slow (possibly cholinergic) and fast (possibly GABAergic) conducting fibers. The muscarine-induced excitations in SHNs were found not to be mediated via M1, M2 or M4 receptors, as they were not blocked by the M1-selective antagonists, pirenzepine or telenzepine or by the M2/M4-selective antagonist, methoctramine. In contrast, the M3-selective antagonist, 4-DAMP-mustard, blocked muscarinic excitations in a majority of SHNs, indicating the presence of M3 as well as non-M3-type responses. McN-A-343, an M1 and M5-selective agonist, excited 33% of neurons tested, confirming involvement of non-M3 receptors (possibly M5) and M3 receptors. Since the cholinergic and GABAergic MSDB neurons together innervate almost every type of hippocampal neuron, the effects of muscarine on SHNs would also have a profound effect on hippocampal circuitry.
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Affiliation(s)
- W Liu
- Department of Psychiatry, CMHC 306, Yale University School of Medicine, 34 Park Street, New Haven, CT 06508, USA
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48
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Kishimoto T, Domino EF. Effects of tobacco smoking and abstinence on middle latency auditory evoked potentials. Clin Pharmacol Ther 1998; 63:571-9. [PMID: 9630830 DOI: 10.1016/s0009-9236(98)90108-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To evaluate the effects of tobacco cigarette smoking and overnight abstinence on middle latency auditory evoked potentials among smokers and nonsmokers. METHODS Groups of 9 to 10 adult male and female nonsmokers and smokers participated in the study. Each person volunteered for two laboratory sessions conducted in the early afternoon on 2 separate days. Smokers abstained from tobacco products 6 to 15 hours before the abstinent session and maintained their usual smoking behavior before the smoking session. The nonsmokers had a similar laboratory experience but sham smoked by means of inhaling air. Middle latency auditory evoked potentials were recorded from Cz to both ears as reference. RESULT The latencies of the Na and Pa potentials during the smoking session were significantly (p < 0.01) shorter than those in abstinent smokers and nonsmokers. After smoking, peak-to-trough amplitudes for the V-Na, Na-Pa, and Pa-Nb potentials were larger than those after abstinence and significantly larger than those among nonsmokers. CONCLUSIONS The shorter latencies of the middle latency brain wave components in the smoking session suggest faster processing of sensory information after cigarette smoking. Larger Pa amplitudes after cigarette smoking suggest a higher arousal level than that among partially abstinent smokers and nonsmokers.
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Affiliation(s)
- T Kishimoto
- Department of Pharmacology, University of Michigan, Ann Arbor 48109-0632, USA
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49
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Liu W, Alreja M. Atypical antipsychotics block the excitatory effects of serotonin in septohippocampal neurons in the rat. Neuroscience 1997; 79:369-82. [PMID: 9200722 DOI: 10.1016/s0306-4522(96)00697-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We recently reported that serotonin excites a subpopulation of GABAergic neurons in the rat medial septum/diagonal band of Broca complex via multiple serotonin receptors, including the serotonin2A subtype. Since a subpopulation of medial septum/diagonal band GABAergic neurons projects to the hippocampus, in the present study we tested the effect of serotonin on antidromically-activated septohippocampal neurons using extracellular recordings. Bath-applied serotonin had an excitatory effect in a majority of septohippocampal neurons; serotonin-excited septohippocampal neurons had a mean conduction velocity -1.63 +/- 0.07 m/s (n=101). Pharmacologically, MDL 100,907, a selective serotonin2A antagonist blocked the excitatory effect of serotonin in 78% of septohippocampal neurons tested, with a mean pA2 of 8.51 +/- 0.12 (n=22). Additionally, the atypical antipsychotics risperidone and clozapine but not the typical antipsychotic haloperidol, blocked the excitatory effects of serotonin at clinically relevant concentrations. The pA2 values of 8.84 +/- 0.11, 6.57 +/- 0.13 and 5.94 +/- 0.27 for risperidone, clozapine and haloperidol, respectively, obtained in the present study, give a rank order of potency risperidone (1.6 nM) clozapine (269 nM) haloperidol (1.1 microM) which corresponds to that reported in binding studies. Additionally, in whole-cell patch-clamp recordings, risperidone (10 nM) blocked serotonin-induced increase in GABAergic synaptic currents. In conclusion, serotonin excites septohippocampal neurons primarily via the serotonin2A receptor and atypical antipsychotics block this excitation at clinically relevant concentrations.
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Affiliation(s)
- W Liu
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06508, U.S.A
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50
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Flach KA, Adler LE, Gerhardt GA, Miller C, Bickford P, MacGregor RJ. Sensory gating in a computer model of the CA3 neural network of the hippocampus. Biol Psychiatry 1996; 40:1230-45. [PMID: 8959288 DOI: 10.1016/0006-3223(95)00624-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have developed a unique computer model of the CA3 region of the hippocampus that simulates the P50 auditory evoked potential response to repeated stimuli in order to study the neuronal circuits involved in a sensory processing deficit associated with schizophrenia. Our computer model of the CA3 hippocampal network includes recurrent activation from within the CA3 region as well as input from the entorhinal cortex and the medial septal nucleus. We used the model to help us determine if the cortical and septal inputs to the CA3 hippocampus alone are responsible for the gating of auditory evoked activity, or if the strong recurrent activity within the CA3 region contributes to this phenomenon. The model suggests that the medial septal input is critical for normal gating; however, to a large extent the activity of the medial septal input can be replaced by simulated stimulation of the hippocampal neurons by a nicotinic agonist. The model is thus consistent with experimental data that show that nicotine restores gating of the N40 evoked potential in fimbria-fornix lesioned rats and of the P50 evoked potential in schizophrenic patients.
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Affiliation(s)
- K A Flach
- University of Colorado, Department of Aerospace Engineering, Boulder, USA
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