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Zheng A, Schmid S. A review of the neural basis underlying the acoustic startle response with a focus on recent developments in mammals. Neurosci Biobehav Rev 2023; 148:105129. [PMID: 36914078 DOI: 10.1016/j.neubiorev.2023.105129] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/13/2023]
Abstract
The startle response consists of whole-body muscle contractions, eye-blink, accelerated heart rate, and freezing in response to a strong, sudden stimulus. It is evolutionarily preserved and can be observed in any animal that can perceive sensory signals, indicating the important protective function of startle. Startle response measurements and its alterations have become a valuable tool for exploring sensorimotor processes and sensory gating, especially in the context of pathologies of psychiatric disorders. The last reviews on the neural substrates underlying acoustic startle were published around 20 years ago. Advancements in methods and techniques have since allowed new insights into acoustic startle mechanisms. This review is focused on the neural circuitry that drives the primary acoustic startle response in mammals. However, there have also been very successful efforts to identify the acoustic startle pathway in other vertebrates and invertebrates in the past decades, so at the end we briefly summarize these studies and comment on the similarities and differences between species.
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Affiliation(s)
- Alice Zheng
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, Canada
| | - Susanne Schmid
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, University of Western Ontario, Canada.
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García-Hernández S, Rubio ME. Role of GluA4 in the acoustic and tactile startle responses. Hear Res 2022; 414:108410. [PMID: 34915397 PMCID: PMC8776314 DOI: 10.1016/j.heares.2021.108410] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 08/26/2021] [Accepted: 12/06/2021] [Indexed: 02/03/2023]
Abstract
The primary startle response (SR) is an innate reaction evoked by sudden and intense acoustic, tactile or visual stimuli. In rodents and humans the SR involves reflexive contractions of the face, neck and limb muscles. The acoustic startle response (ASR) pathway consists of auditory nerve fibers (AN), cochlear root neurons (CRNs) and giant neurons of the caudal pontine reticular nucleus (PnC), which synapse on cranial and spinal motor neurons. The tactile startle response (TSR) is transmitted by primary sensory neurons to the principal sensory (Pr5) and spinal (Sp5) trigeminal nuclei. The ventral part of Pr5 projects directly to the PnC neurons. The SR requires rapid transmission of sensory information to initiate a fast motor response. Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPAR) are necessary to transmit auditory information to the PnC neurons and elicit the SR. AMPARs containing the glutamate AMPAR subunit 4 (GluA4) have fast kinetics, which makes them ideal candidates to transmit the SR signal. This study examined the role of GluA4 within the primary SR pathway by using GluA4 knockout (GluA4-KO) mice. Deletion of GluA4 considerably decreased the amplitude and probability of successful ASR and TSR, indicating that the presence of this subunit is critical at a common station within the startle pathway. We conclude that deletion of GluA4 affects the transmission of sensory signals from acoustic and tactile pathways to the motor component of the startle reflex. Therefore, GluA4 is required for the full response and for reliable elicitation of the startle response.
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Affiliation(s)
- Sofía García-Hernández
- Corresponding authors. Sofía García-Hernández, María E. Rubio, Departments of Neurobiology and Otolaryngology, University of Pittsburgh Medical School, BST3 Building, 3501 Fifth Avenue #10016, Pittsburgh, PA 15261, ,
| | - María E. Rubio
- Corresponding authors. Sofía García-Hernández, María E. Rubio, Departments of Neurobiology and Otolaryngology, University of Pittsburgh Medical School, BST3 Building, 3501 Fifth Avenue #10016, Pittsburgh, PA 15261, ,
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Cano JC, Huang W, Fénelon K. The amygdala modulates prepulse inhibition of the auditory startle reflex through excitatory inputs to the caudal pontine reticular nucleus. BMC Biol 2021; 19:116. [PMID: 34082731 PMCID: PMC8176709 DOI: 10.1186/s12915-021-01050-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 05/12/2021] [Indexed: 01/20/2023] Open
Abstract
Background Sensorimotor gating is a fundamental pre-attentive process that is defined as the inhibition of a motor response by a sensory event. Sensorimotor gating, commonly measured using the prepulse inhibition (PPI) of the auditory startle reflex task, is impaired in patients suffering from various neurological and psychiatric disorders. PPI deficits are a hallmark of schizophrenia, and they are often associated with attention and other cognitive impairments. Although the reversal of PPI deficits in animal models is widely used in pre-clinical research for antipsychotic drug screening, the neurotransmitter systems and synaptic mechanisms underlying PPI are still not resolved, even under physiological conditions. Recent evidence ruled out the longstanding hypothesis that PPI is mediated by midbrain cholinergic inputs to the caudal pontine reticular nucleus (PnC). Instead, glutamatergic, glycinergic, and GABAergic inhibitory mechanisms are now suggested to be crucial for PPI, at the PnC level. Since amygdalar dysfunctions alter PPI and are common to pathologies displaying sensorimotor gating deficits, the present study was designed to test that direct projections to the PnC originating from the amygdala contribute to PPI. Results Using wild type and transgenic mice expressing eGFP under the control of the glycine transporter type 2 promoter (GlyT2-eGFP mice), we first employed tract-tracing, morphological reconstructions, and immunohistochemical analyses to demonstrate that the central nucleus of the amygdala (CeA) sends glutamatergic inputs lateroventrally to PnC neurons, including GlyT2+ cells. Then, we showed the contribution of the CeA-PnC excitatory synapses to PPI in vivo by demonstrating that optogenetic inhibition of this connection decreases PPI, and optogenetic activation induces partial PPI. Finally, in GlyT2-Cre mice, whole-cell recordings of GlyT2+ PnC neurons in vitro paired with optogenetic stimulation of CeA fibers, as well as photo-inhibition of GlyT2+ PnC neurons in vivo, allowed us to implicate GlyT2+ neurons in the PPI pathway. Conclusions Our results uncover a feedforward inhibitory mechanism within the brainstem startle circuit by which amygdalar glutamatergic inputs and GlyT2+ PnC neurons contribute to PPI. We are providing new insights to the clinically relevant theoretical construct of PPI, which is disrupted in various neuropsychiatric and neurological diseases. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01050-z.
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Affiliation(s)
- Jose Carlos Cano
- Department of Biological Sciences, University of Texas at El Paso, 500 West University Avenue, El Paso, TX, 79912, USA
| | - Wanyun Huang
- Biology Department, University of Massachusetts Amherst, Life Science Laboratories, 240 Thatcher Road, Amherst, MA, 01002, USA
| | - Karine Fénelon
- Biology Department, University of Massachusetts Amherst, Life Science Laboratories, 240 Thatcher Road, Amherst, MA, 01002, USA.
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Marquart GD, Tabor KM, Bergeron SA, Briggman KL, Burgess HA. Prepontine non-giant neurons drive flexible escape behavior in zebrafish. PLoS Biol 2019; 17:e3000480. [PMID: 31613896 PMCID: PMC6793939 DOI: 10.1371/journal.pbio.3000480] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/10/2019] [Indexed: 11/18/2022] Open
Abstract
Many species execute ballistic escape reactions to avoid imminent danger. Despite fast reaction times, responses are often highly regulated, reflecting a trade-off between costly motor actions and perceived threat level. However, how sensory cues are integrated within premotor escape circuits remains poorly understood. Here, we show that in zebrafish, less precipitous threats elicit a delayed escape, characterized by flexible trajectories, which are driven by a cluster of 38 prepontine neurons that are completely separate from the fast escape pathway. Whereas neurons that initiate rapid escapes receive direct auditory input and drive motor neurons, input and output pathways for delayed escapes are indirect, facilitating integration of cross-modal sensory information. These results show that rapid decision-making in the escape system is enabled by parallel pathways for ballistic responses and flexible delayed actions and defines a neuronal substrate for hierarchical choice in the vertebrate nervous system.
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Affiliation(s)
- Gregory D. Marquart
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
- Neuroscience and Cognitive Science Program, University of Maryland, Maryland, United States of America
| | - Kathryn M. Tabor
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
| | - Sadie A. Bergeron
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
| | - Kevin L. Briggman
- Circuit Dynamics and Connectivity Unit, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland, United States of America
| | - Harold A. Burgess
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland, United States of America
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Lauer AM, Behrens D, Klump G. Acoustic startle modification as a tool for evaluating auditory function of the mouse: Progress, pitfalls, and potential. Neurosci Biobehav Rev 2017; 77:194-208. [PMID: 28327385 PMCID: PMC5446932 DOI: 10.1016/j.neubiorev.2017.03.009] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/23/2017] [Accepted: 03/13/2017] [Indexed: 12/16/2022]
Abstract
Acoustic startle response (ASR) modification procedures, especially prepulse inhibition (PPI), are increasingly used as behavioral measures of auditory processing and sensorimotor gating in rodents due to their perceived ease of implementation and short testing times. In practice, ASR and PPI procedures are extremely variable across animals, experimental setups, and studies, and the interpretation of results is subject to numerous caveats and confounding influences. We review considerations for modification of the ASR using acoustic stimuli, and we compare the sensitivity of PPI procedures to more traditional operant psychoacoustic techniques. We also discuss non-auditory variables that must be considered. We conclude that ASR and PPI measures cannot substitute for traditional operant techniques due to their low sensitivity. Additionally, a substantial amount of pilot testing must be performed to properly optimize an ASR modification experiment, negating any time benefit over operant conditioning. Nevertheless, there are some circumstances where ASR measures may be the only option for assessing auditory behavior, such as when testing mouse strains with early-onset hearing loss or learning impairments.
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Affiliation(s)
- Amanda M Lauer
- Department of Otolaryngology-Head and Neck Surgery and Center for Hearing and Balance, Johns Hopkins University, 515 Traylor Building, 720 Rutland Ave., Baltimore, MD 21205, USA.
| | - Derik Behrens
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
| | - Georg Klump
- Cluster of Excellence Hearing4all, Animal Physiology & Behavior Group, Department for Neuroscience, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, Carl Von Ossietzky Str. 9-11, 26111 Oldenburg, Germany
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McCall AA, Miller DM, Yates BJ. Descending Influences on Vestibulospinal and Vestibulosympathetic Reflexes. Front Neurol 2017; 8:112. [PMID: 28396651 PMCID: PMC5366978 DOI: 10.3389/fneur.2017.00112] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 03/09/2017] [Indexed: 12/15/2022] Open
Abstract
This review considers the integration of vestibular and other signals by the central nervous system pathways that participate in balance control and blood pressure regulation, with an emphasis on how this integration may modify posture-related responses in accordance with behavioral context. Two pathways convey vestibular signals to limb motoneurons: the lateral vestibulospinal tract and reticulospinal projections. Both pathways receive direct inputs from the cerebral cortex and cerebellum, and also integrate vestibular, spinal, and other inputs. Decerebration in animals or strokes that interrupt corticobulbar projections in humans alter the gain of vestibulospinal reflexes and the responses of vestibular nucleus neurons to particular stimuli. This evidence shows that supratentorial regions modify the activity of the vestibular system, but the functional importance of descending influences on vestibulospinal reflexes acting on the limbs is currently unknown. It is often overlooked that the vestibulospinal and reticulospinal systems mainly terminate on spinal interneurons, and not directly on motoneurons, yet little is known about the transformation of vestibular signals that occurs in the spinal cord. Unexpected changes in body position that elicit vestibulospinal reflexes can also produce vestibulosympathetic responses that serve to maintain stable blood pressure. Vestibulosympathetic reflexes are mediated, at least in part, through a specialized group of reticulospinal neurons in the rostral ventrolateral medulla that project to sympathetic preganglionic neurons in the spinal cord. However, other pathways may also contribute to these responses, including those that dually participate in motor control and regulation of sympathetic nervous system activity. Vestibulosympathetic reflexes differ in conscious and decerebrate animals, indicating that supratentorial regions alter these responses. However, as with vestibular reflexes acting on the limbs, little is known about the physiological significance of descending control of vestibulosympathetic pathways.
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Affiliation(s)
- Andrew A McCall
- Department of Otolaryngology, University of Pittsburgh School of Medicine , Pittsburgh, PA , USA
| | - Derek M Miller
- Department of Otolaryngology, University of Pittsburgh School of Medicine , Pittsburgh, PA , USA
| | - Bill J Yates
- Department of Otolaryngology, University of Pittsburgh School of Medicine , Pittsburgh, PA , USA
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Leon-Sarmiento FE, Peckham E, Leon-Ariza DS, Bara-Jimenez W, Hallett M. Auditory and Lower Limb Tactile Prepulse Inhibition in Primary Restless Legs Syndrome: Clues to Its Pathophysiology. J Clin Neurophysiol 2016; 32:369-74. [PMID: 26241246 DOI: 10.1097/wnp.0000000000000196] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The resting sensory discomfort transiently relieved upon movement of the affected area in restless legs syndrome suggests that sensorimotor integration mechanisms, specifically gating, may be altered in the disease. The authors sought to determine the effects of prepulse auditory and tactile stimulation applied to lower limbs on the blink reflex of patients with restless legs syndrome and healthy subjects. Seventeen patients with restless legs syndrome and 17 age- and sex-matched healthy controls were investigated. Auditory stimuli and tactile lower limb stimulation were applied as prepulses. The R2 response of the blink reflex induced by electrical stimulation applied to the right supraorbital nerve was selected as the test stimulus. Time intervals between prepulses and response-eliciting stimuli were 40, 70, 90, 110, and 200 milliseconds. There were no differences in either the auditory or tactile prepulse conditions between patients and controls and no differences between these measures within subject groups. We concluded that the tactile lower limb and the auditory prepulse effects on the brainstem interneurons mediating the blink reflex share common neural pathways. Because forebrain interneurons mediate these prepulse effects, they are likely not involved in the disordered sensorimotor interaction of restless legs syndrome.
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Affiliation(s)
- Fidias E Leon-Sarmiento
- *Human Motor Control Section, NINDS, National Institutes of Health, Bethesda, Maryland, U.S.A.; †Smell and Taste Center, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, U.S.A.; ‡Mediciencias Research Group, Unicolciencias/Universidad Nacional, Bogota, Colombia; and §Faculty of Health, Universidad de Santander (UDES), Bucaramanga, Colombia
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Mercante B, Pilurzi G, Ginatempo F, Manca A, Follesa P, Tolu E, Deriu F. Trigeminal nerve stimulation modulates brainstem more than cortical excitability in healthy humans. Exp Brain Res 2015; 233:3301-11. [DOI: 10.1007/s00221-015-4398-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 07/27/2015] [Indexed: 12/30/2022]
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Yeomans JS, Bosch D, Alves N, Daros A, Ure RJ, Schmid S. GABA receptors and prepulse inhibition of acoustic startle in mice and rats. Eur J Neurosci 2010; 31:2053-61. [DOI: 10.1111/j.1460-9568.2010.07236.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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