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Hiser J, Schneider B, Koenigs M. Uncertainty Potentiates Neural and Cardiac Responses to Visual Stimuli in Anxiety Disorders. BIOLOGICAL PSYCHIATRY: COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2021; 6:725-734. [PMID: 33592312 DOI: 10.1016/j.bpsc.2021.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/03/2021] [Accepted: 02/05/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Intolerance of uncertainty and worry about future events are cardinal features of anxiety. However, the neurobiological and physiological mechanisms underlying these characteristics of anxiety remain to be fully elucidated. METHODS Individuals with diagnosed anxiety disorders (n = 29, 22 female) and age-matched comparison subjects (n = 28, 17 female) completed a task in which pictures (aversive or neutral content) were preceded by cues indicating certainty or uncertainty about the emotional valence of the subsequent pictures. We assessed functional magnetic resonance imaging and heart rate activity with respect to the 1) cue period, 2) emotional valence of the pictures, and 3) modulatory effect of uncertainty on responses to subsequent pictures. RESULTS Individuals with anxiety disorders and comparison subjects exhibited similar functional magnetic resonance imaging and cardiac activity during the cue period and for the aversive versus neutral picture contrast. However, individuals with anxiety disorders exhibited greater modulatory effects of uncertainty on their responses to subsequent pictures. Specifically, they displayed greater functional magnetic resonance imaging activity in a number of cortical regions (visual cortex, anterior cingulate cortex, superior temporal gyrus, and anterior insula), as well as significantly reduced cardiac deceleration to pictures preceded by the uncertainty cue. CONCLUSIONS These findings suggest that heightened neural and autonomic reactivity to stimuli during conditions of uncertainty may be a key psychobiological mechanism of anxiety.
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Affiliation(s)
- Jaryd Hiser
- Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin; Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin.
| | - Brett Schneider
- Department of Psychology, University of Wisconsin-Madison, Madison, Wisconsin; Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin
| | - Michael Koenigs
- Department of Psychiatry, University of Wisconsin-Madison, Madison, Wisconsin
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Piantadosi PT, Yeates DCM, Floresco SB. Prefrontal cortical and nucleus accumbens contributions to discriminative conditioned suppression of reward-seeking. ACTA ACUST UNITED AC 2020; 27:429-440. [PMID: 32934096 PMCID: PMC7497111 DOI: 10.1101/lm.051912.120] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 07/02/2020] [Indexed: 12/18/2022]
Abstract
Fear can potently inhibit ongoing behavior, including reward-seeking, yet the neural circuits that underlie such suppression remain to be clarified. Prior studies have demonstrated that distinct subregions of the rodent medial prefrontal cortex (mPFC) differentially affect fear behavior, whereby fear expression is promoted by the more dorsal prelimbic cortex (PL) and inhibited by the more ventral infralimbic cortex (IL). These mPFC regions project to subregions of the nucleus accumbens, the core (NAcC) and shell (NAcS), that differentially contribute to reward-seeking as well as affective processes that may be relevant to fear expression. Here, we investigated how these mPFC and NAc subregions contribute to discriminative fear conditioning, assessed by conditioned suppression of reward-seeking. Bilateral inactivation of the NAcS or PL reduced the expression of conditioned suppression to a shock-associated CS+, whereas NAcC inactivation reduced reward-seeking without affecting suppression. IL inactivation caused a general reduction in conditioned suppression following discriminative conditioning, but not when using a single-stimulus design. Pharmacological disconnection of the PL → NAcS pathway revealed that this projection mediates conditioned suppression. These data add to a growing literature implicating discrete cortico-striatal pathways in the suppression of reward-seeking in response to aversive stimuli. Dysfunction within related structures may contribute to aberrant patterns of behavior in psychiatric illnesses including substance use disorders.
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Affiliation(s)
- Patrick T Piantadosi
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Dylan C M Yeates
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Stan B Floresco
- Department of Psychology and Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Amphetamine disrupts haemodynamic correlates of prediction errors in nucleus accumbens and orbitofrontal cortex. Neuropsychopharmacology 2020; 45:793-803. [PMID: 31703234 PMCID: PMC7075902 DOI: 10.1038/s41386-019-0564-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 10/02/2019] [Accepted: 10/29/2019] [Indexed: 11/08/2022]
Abstract
In an uncertain world, the ability to predict and update the relationships between environmental cues and outcomes is a fundamental element of adaptive behaviour. This type of learning is typically thought to depend on prediction error, the difference between expected and experienced events and in the reward domain that has been closely linked to mesolimbic dopamine. There is also increasing behavioural and neuroimaging evidence that disruption to this process may be a cross-diagnostic feature of several neuropsychiatric and neurological disorders in which dopamine is dysregulated. However, the precise relationship between haemodynamic measures, dopamine and reward-guided learning remains unclear. To help address this issue, we used a translational technique, oxygen amperometry, to record haemodynamic signals in the nucleus accumbens (NAc) and orbitofrontal cortex (OFC), while freely moving rats performed a probabilistic Pavlovian learning task. Using a model-based analysis approach to account for individual variations in learning, we found that the oxygen signal in the NAc correlated with a reward prediction error, whereas in the OFC it correlated with an unsigned prediction error or salience signal. Furthermore, an acute dose of amphetamine, creating a hyperdopaminergic state, disrupted rats' ability to discriminate between cues associated with either a high or a low probability of reward and concomitantly corrupted prediction error signalling. These results demonstrate parallel but distinct prediction error signals in NAc and OFC during learning, both of which are affected by psychostimulant administration. Furthermore, they establish the viability of tracking and manipulating haemodynamic signatures of reward-guided learning observed in human fMRI studies by using a proxy signal for BOLD in a freely behaving rodent.
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Enhanced discriminative aversive learning and amygdala responsivity in 5-HT transporter mutant mice. Transl Psychiatry 2019; 9:139. [PMID: 30996249 PMCID: PMC6470159 DOI: 10.1038/s41398-019-0476-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 02/07/2019] [Accepted: 02/12/2019] [Indexed: 12/31/2022] Open
Abstract
Genetic variation in the human serotonin transporter (5-HTT) has been linked to altered fear learning but the data are inconsistent and the mechanism is unclear. The present study investigated conditioned aversive learning in 5-HTT knockout (KO) mice while simultaneously recording neural network activity (theta oscillations) and hemodynamic responses (tissue oxygen delivery) from the amygdala, a brain region necessary for forming fearful memories. Conditioned aversive learning was measured using a discrimination learning task in which one auditory cue was paired with foot-shock, whereas a second auditory cue was not. Compared with wild-type mice, 5-HTTKO mice exhibited faster discrimination learning. This effect was associated with stronger theta frequency oscillations and greater hemodynamic changes in the amygdala in response to both the emotionally relevant cues and the unconditioned foot-shock stimulus. Furthermore, hemodynamic responses to the unconditioned stimulus predicted behavioral discrimination performance the following day. Acute pharmacological 5-HTT blockade in wild-type mice produced a similar effect, to the extent that administration of citalopram during the fear conditioning sessions enhanced fear memory recall. Collectively, our data argue that loss of 5-HTT function enhances amygdala responsivity to aversive events and facilitates learning for emotionally relevant cues.
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Generalization of Conditioned Auditory Fear is Regulated by Maternal Effects on Ventral Hippocampal Synaptic Plasticity. Neuropsychopharmacology 2018; 43:1297-1307. [PMID: 29154366 PMCID: PMC5916357 DOI: 10.1038/npp.2017.281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 09/30/2017] [Accepted: 11/12/2017] [Indexed: 01/09/2023]
Abstract
Maternal care shapes individual differences in fear-associated neural circuitry. In rats, maternal licking and grooming (LG) in early life regulates ventral hippocampal (VH) function and plasticity in adulthood, but its consequent effect on the regulation of fear memories remains unknown. We report an effect of maternal care on generalization of learned fear, such that offspring of high LG mothers express generalized fear responses when confronted with neutral stimuli following auditory fear conditioning. These animals simultaneously display a reduction in the magnitude of VH long-term potentiation (LTP) expressed and reduced input-output transformation in Schaffer collateral synapses. Inhibition of VH-LTP during learning specifically increases fear generalization in offspring of low LG mothers during recall, suggesting a role for VH synaptic plasticity in the specification of fear memories. These findings suggest that rearing by low LG dams enhances the efficacy of fear-related neural systems to support accurate encoding of fear memories through effects on the VH.
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Xiao C, Liu Y, Xu J, Gan X, Xiao Z. Septal and Hippocampal Neurons Contribute to Auditory Relay and Fear Conditioning. Front Cell Neurosci 2018; 12:102. [PMID: 29713265 PMCID: PMC5911473 DOI: 10.3389/fncel.2018.00102] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 03/28/2018] [Indexed: 01/30/2023] Open
Abstract
The hippocampus has been thought to process auditory information. However, the properties, pathway, and role of hippocampal auditory responses are unclear. With loose-patch recordings, we found that hippocampal neurons are mainly responsive to noise and are not tonotopically organized. Their latencies are shorter than those of primary auditory cortical (A1) neurons but longer than those of medial septal (MS) neurons, suggesting that hippocampal auditory information comes from MS neurons rather than from A1 neurons. Silencing the MS blocks both hippocampal auditory responses and memory of auditory fear conditioning trained with noise and tone. Auditory fear conditioning was associated with some cues but not with a specific frequency of sound, as demonstrated by animals trained with noise, 2.5-, 5-, 10-, 15-, or 30-kHz tones, and tested with these sounds. Therefore, the noise responses of hippocampal neurons have identified a population of neurons that can be associated with auditory fear conditioning.
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Affiliation(s)
- Cuiyu Xiao
- Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yun Liu
- Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Jian Xu
- Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Xiong Gan
- Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Zhongju Xiao
- Key Laboratory of Psychiatric Disorders of Guangdong Province, Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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Li J, Schwarz AJ, Gilmour G. Relating Translational Neuroimaging and Amperometric Endpoints: Utility for Neuropsychiatric Drug Discovery. Curr Top Behav Neurosci 2016; 28:397-421. [PMID: 27023366 DOI: 10.1007/7854_2016_1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Measures of neuronal activation are a natural and parsimonious translational biomarker to consider in the context of neuropsychiatric drug discovery studies. In this regard, functional neuroimaging using the BOLD fMRI technique is becoming more frequently employed to not only probe aberrant brain regions and circuits in disease, but also to assess the effects of novel pharmacological agents on these processes. In the ideal situation, these types of studies would first be conducted pre-clinically in rodents to confirm a measurable functional response on relevant brain circuits before seeking to replicate the findings in an analogous fMRI paradigm in humans. However, the need for animal immobilization during the scanning procedure precludes all but the simplest behavioural task-based paradigms in rodent BOLD fMRI. This chapter considers how in vivo oxygen amperometry may represent a viable and valid proxy for BOLD fMRI in freely moving rodents engaged in behavioural tasks. The amperometric technique and several examples of emerging evidence are described to show how the technique can deliver results that translate to pharmacological, event-related and functional connectivity variants of fMRI. In vivo oxygen amperometry holds great promise as a technique that may help to bridge the gap between basic drug discovery research in rodents and applied efficacy testing in humans.
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Affiliation(s)
- Jennifer Li
- In Vivo Pharmacology, Eli Lilly and Company, Erl Wood Manor, Sunninghill Road, Windlesham, UK
| | - Adam J Schwarz
- Translational Imaging, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Gary Gilmour
- In Vivo Pharmacology, Eli Lilly and Company, Erl Wood Manor, Sunninghill Road, Windlesham, UK.
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McHugh SB, Barkus C, Lima J, Glover LR, Sharp T, Bannerman DM. SERT and uncertainty: serotonin transporter expression influences information processing biases for ambiguous aversive cues in mice. GENES BRAIN AND BEHAVIOR 2015; 14:330-6. [PMID: 25824641 PMCID: PMC4440341 DOI: 10.1111/gbb.12215] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 03/26/2015] [Accepted: 03/26/2015] [Indexed: 12/18/2022]
Abstract
The long allele variant of the serotonin transporter (SERT, 5-HTT) gene-linked polymorphic region (5-HTTLPR) is associated with higher levels of 5-HTT expression and reduced risk of developing affective disorders. However, little is known about the mechanisms underlying this protective effect. One hypothesis is that 5-HTT expression influences aversive information processing, with reduced negative cognitive bias present in those with higher 5-HTT expression. Here we investigated this hypothesis using genetically-modified mice and a novel aversive learning paradigm. Mice with high levels of 5-HTT expression (5-HTT over-expressing, 5-HTTOE mice) and wild-type mice were trained to discriminate between three distinct auditory cues: one cue predicted footshock on all trials (CS+); a second cue predicted the absence of footshock (CS−); and a third cue predicted footshock on 20% of trials (CS20%), and was therefore ambiguous. Wild-type mice exhibited equivalently high levels of fear to the CS+ and CS20% and minimal fear to the CS−. In contrast, 5-HTTOE mice exhibited high levels of fear to the CS+ but minimal fear to the CS− and the CS20%. This selective reduction in fear to ambiguous aversive cues suggests that increased 5-HTT expression reduces negative cognitive bias for stimuli with uncertain outcomes.
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Affiliation(s)
- S B McHugh
- Department of Experimental Psychology, University of Oxford, Oxford, UK
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Abstract
While resting-state functional magnetic resonance imaging can probe intrinsic network connectivity in both human and rodent brain, behavioral modulation of these connectivity patterns has not yet been demonstrated in the rodent due to the requirements of immobilization or anesthesia for MRI scanning. To enable the effects of behavioral tasks on functional connectivity to be measured in freely moving, awake rats, implanted carbon paste electrodes (CPEs) were used to monitor low-frequency fluctuations of tissue oxygenation. Rats were implanted with CPEs in two nodes of the default mode network (DMN) and two nodes in a lateral cortical network, revealing amperometric oxygen correlation patterns consistent with imaging studies. Using a block design study where rats alternated between sustained periods of instrumental response and unscheduled spontaneous behavior, task-induced decreases in functional connectivity were observed between the DMN node pair, but not in the distinct lateral cortical network, demonstrating network-specific modulation of functional connectivity.
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Straube B, Lueken U, Jansen A, Konrad C, Gloster AT, Gerlach AL, Ströhle A, Wittmann A, Pfleiderer B, Gauggel S, Wittchen U, Arolt V, Kircher T. Neural correlates of procedural variants in cognitive-behavioral therapy: a randomized, controlled multicenter FMRI study. PSYCHOTHERAPY AND PSYCHOSOMATICS 2015; 83:222-33. [PMID: 24970601 DOI: 10.1159/000359955] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 01/19/2014] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cognitive behavioral therapy (CBT) is an effective treatment for panic disorder with agoraphobia (PD/AG). It is unknown, how variants of CBT differentially modulate brain networks involved in PD/AG. This study was aimed to evaluate the effects of therapist-guided (T+) versus self-guided (T-) exposure on the neural correlates of fear conditioning in PD/AG. METHOD In a randomized, controlled multicenter clinical trial in medication-free patients with PD/AG who were treated with 12 sessions of manualized CBT, functional magnetic resonance imaging (fMRI) was used during fear conditioning before (t1) and after CBT (t2). Quality-controlled fMRI data from 42 patients and 42 healthy subjects (HS) were obtained. Patients were randomized to two variants of CBT (T+, n = 22, and T-, n = 20). RESULTS The interaction of diagnosis (PD/AG, HS), treatment group (T+, T-), time point (t1, t2) and stimulus type (conditioned stimulus: yes, no) revealed activation in the left hippocampus and the occipitotemporal cortex. The T+ group demonstrated increased activation of the hippocampus at t2 (t2 > t1), which was positively correlated with treatment outcome, and a decreased connectivity between the left inferior frontal gyrus and the left hippocampus across time (t1 > t2). CONCLUSION After T+ exposure, contingency-encoding processes related to the posterior hippocampus are augmented and more decoupled from processes of the left inferior frontal gyrus, previously shown to be dysfunctionally activated in PD/AG. Linking single procedural variants to neural substrates offers the potential to inform about the optimization of targeted psychotherapeutic interventions.
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Affiliation(s)
- Benjamin Straube
- Department of Psychiatry and Psychotherapy, Philipps University Marburg, Marburg, Germany
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Prefrontal cortical GABA transmission modulates discrimination and latent inhibition of conditioned fear: relevance for schizophrenia. Neuropsychopharmacology 2014; 39:2473-84. [PMID: 24784549 PMCID: PMC4138759 DOI: 10.1038/npp.2014.99] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/11/2014] [Accepted: 04/28/2014] [Indexed: 02/07/2023]
Abstract
Inhibitory gamma-aminobutyric acid (GABA) transmission within the prefrontal cortex (PFC) regulates numerous functions, and perturbations in GABAergic transmission within this region have been proposed to contribute to some of the cognitive and behavioral abnormalities associated with disorders such as schizophrenia. These abnormalities include deficits in emotional regulation and aberrant attributions of affective salience. Yet, how PFC GABA regulates these types of emotional processes are unclear. To address this issue, we investigated the contribution of PFC GABA transmission to different aspects of Pavlovian emotional learning in rats using translational discriminative fear conditioning and latent inhibition (LI) assays. Reducing prelimbic PFC GABAA transmission via infusions of the antagonist bicuculline before the acquisition or expression of fear conditioning eliminated the ability to discriminate between an aversive conditioned stimulus (CS+) paired with footshock vs a neutral CS-, resembling similar deficits observed in schizophrenic patients. In a separate experiment, blockade of PFC GABAA receptors before CS preexposure (PE) and conditioning did not affect subsequent expression of LI, but did enhance fear in rats that were not preexposed to the CS. In contrast, PFC GABA-blockade before a fear expression test disrupted the recall of learned irrelevance and abolished LI. These data suggest that normal PFC GABA transmission is critical for regulating and mitigating multiple aspects of aversive learning, including discrimination between fear vs safety signals and recall of information about the irrelevance of stimuli. Furthermore, they suggest that similar deficits in emotional regulation observed in schizophrenia may be driven in part by deficient PFC GABA activity.
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Abstract
Prediction error signals are fundamental to learning. Here, in mice, we show that aversive prediction signals are found in the hemodynamic responses and theta oscillations recorded from the basolateral amygdala. During fear conditioning, amygdala responses evoked by footshock progressively decreased, whereas responses evoked by the auditory cue that predicted footshock concomitantly increased. Unexpected footshock evoked larger amygdala responses than expected footshock. The magnitude of the amygdala response to the footshock predicted behavioral responses the following day. The omission of expected footshock led to a decrease below baseline in the amygdala response suggesting a negative aversive prediction error signal. Thus, in mice, amygdala activity conforms to temporal difference models of aversive learning.
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Retigabine calms seizure-induced behavior following status epilepticus. Epilepsy Behav 2014; 37:123-32. [PMID: 25016241 DOI: 10.1016/j.yebeh.2014.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 05/28/2014] [Accepted: 06/07/2014] [Indexed: 12/30/2022]
Abstract
In adult rats, intraperitoneal injection of kainate (KA) results in sustained status epilepticus and persistent behavioral comorbidities such as hyperexcitability, anxiety, and altered response to environmental cues. Intrahippocampal KA also results in sustained status epilepticus and continuous high frequency oscillations in the electroencephalograph (EEG), although subsequent behavioral side effects are unknown. We hypothesized that retigabine, a recently discovered anticonvulsant and potent positive modulator of Kv7 channels, may attenuate seizure-induced behavioral abnormalities. Status epilepticus was induced by administration of KA either intraperitoneally (15 mg/kg) or by single intrahippocampal injection (1.0 μg/0.5 μL). After 24 h, half of systemically KA-treated animals that reached stage 6 seizures were injected once daily with retigabine (5 mg/kg) for 14 continuous days. All groups underwent three behavioral tests--capture and handling, open field, and elevated plus maze--24 h following the last retigabine treatment and were sacrificed at 25-28 days. In the capture and handling test, systemic KA treatment resulted in frisky behavior and resistance to capture with wild attempts to escape during the 1st, 2nd, and 3rd weeks of the observation period. In contrast, these behaviors were attenuated in KA+retigabine-treated animals. In the open-field test, KA-treated animals spent more time in the center zone, but KA+retigabine-treated rats had greater overall activity compared with those having vehicle, KA, or retigabine-only treatment. In the elevated plus maze, KA+retigabine-treated animals traveled greater distances in open and closed arms (proximal and distal) compared with controls, also signifying anxiety reduction. Retigabine-only-treated rats traveled more in the open proximal arms compared with controls, indicating increased hyperlocomotion in normotensive rats. Although treatment with KA+retigabine resulted in anxiolytic-like effects in all three behavioral tasks compared with vehicle, this group did not significantly differ from systemically KA-treated rats in most measurements in open-field and elevated plus maze tasks, suggesting that retigabine may also cause hyperlocomotion unrelated to anxiety level. Despite that intrahippocampal KA-treated rats displayed comparable seizure behavior, epileptiform activity, and hippocampal injury, their behavior resembled the controls, suggesting that molecular and subsequent cellular changes are also partially responsible for anxiolytic-like effects and that these results are likely independent of the hippocampus.
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Li J, Ishiwari K, Conway MW, Francois J, Huxter J, Lowry JP, Schwarz AJ, Tricklebank M, Gilmour G. Dissociable effects of antipsychotics on ketamine-induced changes in regional oxygenation and inter-regional coherence of low frequency oxygen fluctuations in the rat. Neuropsychopharmacology 2014; 39:1635-44. [PMID: 24442094 PMCID: PMC4023136 DOI: 10.1038/npp.2014.10] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 01/13/2014] [Accepted: 01/14/2014] [Indexed: 11/08/2022]
Abstract
Typical and atypical antipsychotics have been shown to alleviate N-methyl-D-aspartate (NMDA) receptor antagonist-induced BOLD signals in healthy humans and animals to differing degrees; factors that might relate to their different molecular mechanisms and clinical profiles. Recent studies have also extended these investigations to the analysis of resting state functional connectivity measures of BOLD signals in different brain regions. Using constant potential amperometry, we examined the effects of the NMDA receptor antagonist S-(+)-ketamine on tissue oxygen levels in medial prefrontal cortex (mPFC) and medial ventral striatum (mVS), and temporal coherence of low-frequency oxygen fluctuations between these regions in freely moving rats. Furthermore, we assessed the extent to which the atypical antipsychotic clozapine and the typical antipsychotic haloperidol could modulate the effects of S-(+)-ketamine on these measures. Acute S-(+)-ketamine (5-25 mg/kg) produced dose-dependent increases in both tissue O2 levels and coherence. Although effects of clozapine and haloperidol alone were relatively minor, their effects on ketamine-induced signals were markedly more distinct. Clozapine dose-dependently attenuated the absolute S-(+)-ketamine (25 mg/kg) O2 signal in both regions, and also attenuated ketamine-induced increases in regional coherence. Haloperidol had no effect on the absolute ketamine O2 signal yet potentiated increases in regional coherence. The dissociable effects of haloperidol and clozapine on ketamine-induced hyperoxygenation and mPFC-mVS coherence elucidate potentially important mechanistic differences between these classes of pharmacology. This study demonstrates for the first time that in vivo amperometry can measure both regional brain tissue O2 levels and inter-regional coherence, advancing BOLD-like measurements of functional connectivity into awake, unconstrained animals.
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Affiliation(s)
- Jennifer Li
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Keita Ishiwari
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
- Department of Chemistry, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Michael W Conway
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Jennifer Francois
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - John Huxter
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - John P Lowry
- Department of Chemistry, National University of Ireland, Maynooth, Co. Kildare, Ireland
| | - Adam J Schwarz
- Tailored Therapeutics, Eli Lilly and Company, Indianapolis, IN, USA
| | - Mark Tricklebank
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
| | - Gary Gilmour
- Centre for Cognitive Neuroscience, Eli Lilly and Co. Limited, Windlesham, Surrey, UK
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Barkus C, Line SJ, Huber A, Capitao L, Lima J, Jennings K, Lowry J, Sharp T, Bannerman DM, McHugh SB. Variation in serotonin transporter expression modulates fear-evoked hemodynamic responses and theta-frequency neuronal oscillations in the amygdala. Biol Psychiatry 2014; 75:901-8. [PMID: 24120093 PMCID: PMC4032572 DOI: 10.1016/j.biopsych.2013.09.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 09/04/2013] [Accepted: 09/04/2013] [Indexed: 01/16/2023]
Abstract
BACKGROUND Gene association studies detect an influence of natural variation in the 5-hydroxytryptamine transporter (5-HTT) gene on multiple aspects of individuality in brain function, ranging from personality traits through to susceptibility to psychiatric disorders such as anxiety and depression. The neural substrates of these associations are unknown. Human neuroimaging studies suggest modulation of the amygdala by 5-HTT variation, but this hypothesis is controversial and unresolved, and difficult to investigate further in humans. METHODS We used a mouse model in which the 5-HTT is overexpressed throughout the brain and recorded hemodynamic responses (using a novel in vivo voltammetric monitoring method, analogous to blood oxygen level-dependent functional magnetic resonance imaging) and local field potentials during Pavlovian fear conditioning. RESULTS Increased 5-HTT expression impaired, but did not prevent, fear learning and significantly reduced amygdala hemodynamic responses to aversive cues. Increased 5-HTT expression was also associated with reduced theta oscillations, which were a feature of aversive cue presentation in controls. Moreover, in control mice, but not those with high 5-HTT expression, there was a strong correlation between theta power and the amplitude of the hemodynamic response. CONCLUSIONS Direct experimental manipulation of 5-HTT expression levels throughout the brain markedly altered fear learning, amygdala hemodynamic responses, and neuronal oscillations.
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Affiliation(s)
- Christopher Barkus
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Samantha J Line
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Anna Huber
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Liliana Capitao
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Joao Lima
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Katie Jennings
- Department of Physiology, Anatomy, and Genetics, University of Oxford, Oxford, United Kingdom
| | - John Lowry
- Department of Chemistry, National University of Ireland, Maynooth, Ireland
| | - Trevor Sharp
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Stephen B McHugh
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
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Díaz-Mataix L, Tallot L, Doyère V. The amygdala: A potential player in timing CS–US intervals. Behav Processes 2014; 101:112-22. [DOI: 10.1016/j.beproc.2013.08.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 07/15/2013] [Accepted: 08/06/2013] [Indexed: 01/29/2023]
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Prefrontal cholinergic mechanisms instigating shifts from monitoring for cues to cue-guided performance: converging electrochemical and fMRI evidence from rats and humans. J Neurosci 2013; 33:8742-52. [PMID: 23678117 DOI: 10.1523/jneurosci.5809-12.2013] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We previously reported involvement of right prefrontal cholinergic activity in veridical signal detection. Here, we first recorded real-time acetylcholine release in prefrontal cortex (PFC) during specific trial sequences in rats performing a task requiring signal detection as well as rejection of nonsignal events. Cholinergic release events recorded with subsecond resolution ("transients") were observed only during signal-hit trials, not during signal-miss trials or nonsignal events. Moreover, cholinergic transients were not observed for consecutive hits; instead they were limited to signal-hit trials that were preceded by factual or perceived nonsignal events ("incongruent hits"). This finding suggests that these transients mediate shifts from a state of perceptual attention, or monitoring for cues, to cue-evoked activation of response rules and the generation of a cue-directed response. Next, to determine the translational significance of the cognitive operations supporting incongruent hits we used a version of the task previously validated for use in research in humans and blood oxygenation level-dependent (BOLD)-functional magnetic resonance imaging. Incongruent hits activated a region in the right rostral PFC (Brodmann area 10). Furthermore, greater prefrontal activation was correlated with faster response times for incongruent hits. Finally, we measured tissue oxygen in rats, as a proxy for BOLD, and found prefrontal increases in oxygen levels solely during incongruent hits. These cross-species studies link a cholinergic response to a prefrontal BOLD activation and indicate that these interrelated mechanisms mediate the integration of external cues with internal representations to initiate and guide behavior.
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Finnerty NJ, Bolger FB, Pålsson E, Lowry JP. An investigation of hypofrontality in an animal model of schizophrenia using real-time microelectrochemical sensors for glucose, oxygen, and nitric oxide. ACS Chem Neurosci 2013; 4:825-31. [PMID: 23578219 DOI: 10.1021/cn4000567] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Glucose, O2, and nitric oxide (NO) were monitored in real time in the prefrontal cortex of freely moving animals using microelectrochemical sensors following phencyclidine (PCP) administration. Injection of saline controls produced a decrease in glucose and increases in both O2 and NO. These changes were short-lived and typical of injection stress, lasting ca. 30 s for glucose and between 2 and 6 min for O2 and NO, respectively. Subchronic PCP (10 mg/kg) resulted in increased motor activity and increases in all three analytes lasting several hours: O2 and glucose were uncoupled with O2 increasing rapidly following injection reaching a maximum of 70% (ca. 62 μM) after ca. 15 min and then slowly returning to baseline over a period of ca. 3 h. The time course of changes in glucose and NO were similar; both signals increased gradually over the first hour post injection reaching maxima of 55% (ca. 982 μM) and 8% (ca. 31 nM), respectively, and remaining elevated to within 1 h of returning to baseline levels (after ca. 5 and 7 h, respectively). While supporting increased utilization of glucose and O2 and suggesting overcompensating supply mechanisms, this neurochemical data indicates a hyperfrontal effect following acute PCP administration which is potentially mediated by NO. It also confirms that long-term in vivo electrochemical sensors and data offer a real-time biochemical perspective of the underlying mechanisms.
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Affiliation(s)
- Niall J. Finnerty
- Department
of Chemistry, National University of Ireland Maynooth, Co. Kildare, Ireland
| | - Fiachra B. Bolger
- Department
of Chemistry, National University of Ireland Maynooth, Co. Kildare, Ireland
| | - Erik Pålsson
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience
and Physiology, The Sahlgrenska Academy at University of Gothenburg, PO Box 431, 405 30 Gothenburg, Sweden
| | - John P. Lowry
- Department
of Chemistry, National University of Ireland Maynooth, Co. Kildare, Ireland
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