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Flores G, Morales-Medina JC, Diaz A. Neuronal and brain morphological changes in animal models of schizophrenia. Behav Brain Res 2016; 301:190-203. [DOI: 10.1016/j.bbr.2015.12.034] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 12/15/2015] [Accepted: 12/18/2015] [Indexed: 12/14/2022]
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Romero-Pimentel AL, Vázquez-Roque RA, Camacho-Abrego I, Hoffman KL, Linares P, Flores G, Manjarrez E. Histological correlates of N40 auditory evoked potentials in adult rats after neonatal ventral hippocampal lesion: animal model of schizophrenia. Schizophr Res 2014; 159:450-7. [PMID: 25261883 DOI: 10.1016/j.schres.2014.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 08/28/2014] [Accepted: 09/04/2014] [Indexed: 11/26/2022]
Abstract
The neonatal ventral hippocampal lesion (NVHL) is an established neurodevelopmental rat model of schizophrenia. Rats with NVHL exhibit several behavioral, molecular and physiological abnormalities that are similar to those found in schizophrenics. Schizophrenia is a severe psychiatric illness characterized by profound disturbances of mental functions including neurophysiological deficits in brain information processing. These deficits can be assessed by auditory evoked potentials (AEPs), where schizophrenics exhibit abnormalities in amplitude, duration and latency of such AEPs. The aim of the present study was to compare the density of cells in the temporal cerebral cortex and the N40-AEP of adult NVHL rats versus adult sham rats. We found that rats with NVHL exhibit significant lower amplitude of the N40-AEP and a significant lower number of cells in bilateral regions of the temporal cerebral cortex compared to sham rats. Because the AEP recordings were obtained from anesthetized rats, we suggest that NVHL leads to inappropriate innervation in thalamic-cortical pathways in the adult rat, leading to altered function of cortical networks involved in processing of primary auditory information.
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Affiliation(s)
- A L Romero-Pimentel
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México; Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - R A Vázquez-Roque
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - I Camacho-Abrego
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - K L Hoffman
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, CP 90070, México
| | - P Linares
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México
| | - G Flores
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
| | - E Manjarrez
- Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, 14 Sur 6301, Col. San Manuel, Puebla, Puebla, CP 72570, México.
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Swerdlow NR, Light GA, Breier MR, Shoemaker JM, Saint Marie RL, Neary AC, Geyer MA, Stevens KE, Powell SB. Sensory and sensorimotor gating deficits after neonatal ventral hippocampal lesions in rats. Dev Neurosci 2012; 34:240-9. [PMID: 22572564 DOI: 10.1159/000336841] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 01/27/2012] [Indexed: 01/20/2023] Open
Abstract
Neonatal ventral hippocampal lesions (NVHLs) in rats lead to reduced prepulse inhibition (PPI) of startle and other behavioral deficits in adulthood that model abnormalities in schizophrenia patients. A neurophysiological deficit in schizophrenia patients and their first-degree relatives is reduced gating of the P50 event-related potential (ERP). N40 ERP gating in rats may be a cross-species analog of P50 gating, and is disrupted in experimental manipulations related to schizophrenia. Here, we tested whether N40 gating as well as PPI is disrupted after NVHLs, using contemporaneous measures of these two conceptually related phenomena. Male rat pups received sham or ibotenic acid NVHLs on postnatal day 7. PPI was tested on days 35 and 56, after which rats were equipped with cortical surface electrodes for ERP measurements. One week later, PPI and N40 gating were measured in a single test, using paired S1-S2 clicks spaced 500 ms apart to elicit N40 gating. Compared to sham-lesioned rats, those with NVHLs exhibited PPI deficits on days 35 and 56. NVHL rats also exhibited reduced N40 gating and reduced PPI, when measured contemporaneously at day 65. Deficits in PPI and N40 gating appeared most pronounced in rats with larger lesions, focused within the ventral hippocampus. In this first report of contemporaneous measures of two important schizophrenia-related phenotypes in NVHL rats, NVHLs reproduce both sensory (N40) and sensorimotor (PPI) gating deficits exhibited in schizophrenia. In this study, lesion effects were detected prior to pubertal onset, and were sustained well into adulthood.
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Affiliation(s)
- Neal R Swerdlow
- Department of Psychiatry, University of California, San Diego, La Jolla, CA 92093, USA.
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Vohs JL, Chambers RA, Krishnan GP, O'Donnell BF, Hetrick WP, Kaiser ST, Berg S, Morzorati SL. Auditory sensory gating in the neonatal ventral hippocampal lesion model of schizophrenia. Neuropsychobiology 2009; 60:12-22. [PMID: 19684419 PMCID: PMC2901590 DOI: 10.1159/000234813] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 04/30/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS The neonatal ventral hippocampal lesion (NVHL) rat model shows biological and behavioral abnormalities similar to schizophrenia. Disturbed sensory gating reflects a consistent neurobiological abnormality in schizophrenia. Although of critical interest, sensory gating has not been evaluated in the NVHL model. METHODS The N40 rat analog of the human P50 was measured to assess sensory response and gating in NVHL and sham rats. Epidural electrodes recorded evoked potentials (EPs), from which amplitudes, latencies, difference scores (S1-S2) and gating ratios (S2/S1) were assessed. Power and phase locking were computed for evoked EEG activity, to test for frequency-specific abnormalities. RESULTS Prolonged S1 N40 latency was detected in the NVHL group, but amplitude and power measures did not differ. NVHL rats demonstrated disturbed phase-locked sensory gating at theta and beta frequencies, as well as reduced phase-locked gamma activity across stimuli, most robustly at S1. CONCLUSIONS While measures of sensory gating obtained from the EP were relatively insensitive to the NVHL model, phase locking across trials was affected. NVHL rats may have increased evoked response temporal variability, similar to patients with schizophrenia. This pattern of findings likely reflects core developmental NVHL disturbances in dorsal hippocampal circuits associated with temporal and frontal areas.
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Affiliation(s)
- Jenifer L. Vohs
- Psychological and Brain Sciences, Indiana University, Bloomington, Ind., USA,*Jenifer L. Vohs, 1101 E. 10th St., Bloomington, IN 47405 (USA), Tel. +1 812 856 4676, E-Mail
| | - R. Andrew Chambers
- Institute for Psychiatric Research, Indiana University School of Medicine, Indianapolis, Ind., USA
| | - Giri P. Krishnan
- Psychological and Brain Sciences, Indiana University, Bloomington, Ind., USA
| | - Brian F. O'Donnell
- Psychological and Brain Sciences, Indiana University, Bloomington, Ind., USA
| | - William P. Hetrick
- Psychological and Brain Sciences, Indiana University, Bloomington, Ind., USA
| | - Samuel T. Kaiser
- Institute for Psychiatric Research, Indiana University School of Medicine, Indianapolis, Ind., USA
| | - Sarah Berg
- Institute for Psychiatric Research, Indiana University School of Medicine, Indianapolis, Ind., USA
| | - Sandra L. Morzorati
- Institute for Psychiatric Research, Indiana University School of Medicine, Indianapolis, Ind., USA
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Keedy SK, Marlow-O'Connor M, Beenken B, Dorflinger J, Abel M, Erwin RJ. Noradrenergic antagonism of the P13 and N40 components of the rat auditory evoked potential. Psychopharmacology (Berl) 2007; 190:117-25. [PMID: 17096083 DOI: 10.1007/s00213-006-0608-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2006] [Accepted: 10/06/2006] [Indexed: 10/23/2022]
Abstract
RATIONALE Two rat auditory evoked potential (AEP) components P13 and N40 are suggested as analogues to the human P50, which has abnormal suppression properties in schizophrenia. However, P50 likely reflects neural activity from several different brain areas. Studies examining each of these components in the rat model have proposed circuitry that involves alpha2 norepinephrine (NE) receptors, and different disruption effects are predicted depending on whether effects are presynaptic or postsynaptic. OBJECTIVES The aim of this paper is to test differential effects of NE antagonism on disruption of normal P13 and N40 expression. MATERIALS AND METHODS AEPs were recorded simultaneously in alert, freely moving rats using the alpha2 antagonist yohimbine. Amplitudes of P13 and N40 elicited by 500-ms interstimulus interval click pairs were measured after administration of a placebo and three doses of the yohimbine. RESULTS A high dose of yohimbine yielded smaller P13 amplitudes to both clicks, consistent with presynaptic action. However, a moderate yohimbine dose yielded increased P13 amplitudes to both clicks. For N40, a moderate dose of yohimbine yielded increased amplitudes to the second stimulus, and a high dose restored normal suppression, which is consistent with previously reported findings. CONCLUSIONS This study demonstrated that noradrenergic activity differentially affects P13 and N40 components. As P13 and N40 are each models of human P50, these findings highlight the complex circuitry that likely underlies P50. An appreciation for these complexities is critical for understanding the mechanisms of the P50 suppression deficit in schizophrenia, which may be influenced by both trait and state factors.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Animals
- Auditory Cortex/drug effects
- Auditory Cortex/physiology
- Auditory Pathways/drug effects
- Auditory Pathways/physiology
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Electroencephalography/drug effects
- Evoked Potentials, Auditory/drug effects
- Evoked Potentials, Auditory/physiology
- Geniculate Bodies/drug effects
- Geniculate Bodies/physiology
- Hippocampus/drug effects
- Hippocampus/physiology
- Male
- Nerve Net/drug effects
- Nerve Net/physiology
- Norepinephrine/antagonists & inhibitors
- Norepinephrine/physiology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha-2/drug effects
- Receptors, Adrenergic, alpha-2/physiology
- Schizophrenic Psychology
- Signal Processing, Computer-Assisted
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
- Yohimbine/pharmacology
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Affiliation(s)
- Sarah K Keedy
- Department of Psychology, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064, USA.
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Swerdlow NR, Geyer MA, Shoemaker JM, Light GA, Braff DL, Stevens KE, Sharp R, Breier M, Neary A, Auerbach PP. Convergence and divergence in the neurochemical regulation of prepulse inhibition of startle and N40 suppression in rats. Neuropsychopharmacology 2006; 31:506-15. [PMID: 16123772 PMCID: PMC1373667 DOI: 10.1038/sj.npp.1300841] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Prepulse inhibition of startle ('PPI'), a cross-species measure of sensorimotor gating, is impaired in schizophrenia patients. Suppression of P50 event-related potentials (ERPs) in response to the second of two clicks ('P50 gating') is also impaired in schizophrenia. Suppression of N40 ERPs to the second of two clicks ('N40 gating') is thought by some to be a rat homolog of human P50 gating. Emerging evidence suggests differences in the neurobiology of deficits detected by PPI vs P50 (or N40) gating. We recorded PPI and N40 gating contemporaneously in rats, to assess convergence and divergence in the neurochemical regulation of these measures. Dose-response studies examined the effects of apomorphine (APO), phencyclidine (PCP) or the 5HT2A agonist DOI on PPI, and on motor responses to stimuli (S1 and S2) that elicit N40 gating. Effects of optimal drug doses on PPI and N40 gating were then assessed in other rats with implanted cortical surface electrodes. APO, PCP and DOI caused dose-dependent disruptions of both PPI and gating of motor responses to N40 stimuli. Reduced PPI reflected diminished prepulse effectiveness, demonstrated by increased startle levels on prepulse+pulse trials. In contrast, reduced gating of motor responses to N40 stimuli reflected a reduced motor response to S1. In separate rats, robust PPI, N40 potentials and N40 gating could be detected within one test. PPI and N40 gating were disrupted by APO, PCP, and DOI. Again, drug effects on PPI reflected increased startle on prepulse+pulse trials, while those on N40 gating reflected reduced ERP responses to S1. In conclusion, when PPI and N40 gating were studied concurrently in rats, drug effects on PPI reflected reduced inhibition of startle by the prepulse, while diminished N40 gating reflected S1 response suppression. Despite similarities in drug sensitivity, these results suggest that distinct neurobiological mechanisms underlie drug-induced deficits in PPI and N40 gating.
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Affiliation(s)
- Neal R Swerdlow
- Department of Psychiatry, UCSD School of Medicine, La Jolla, CA 92093-0804, USA.
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Martin MV, Dong H, Bertchume A, Csernansky JG. Low dose quetiapine reverses deficits in contextual and cued fear conditioning in rats with excitotoxin-induced hippocampal neuropathy. Pharmacol Biochem Behav 2005; 82:263-9. [PMID: 16183107 DOI: 10.1016/j.pbb.2005.08.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 08/16/2005] [Accepted: 08/17/2005] [Indexed: 11/20/2022]
Abstract
Previous studies have demonstrated that adult rats with excitotoxic lesions of the hippocampus display deficits in memory-related behaviors similar to the memory deficits associated with schizophrenia. In this study, we assessed the sub-chronic effects of quetiapine, risperidone and haloperidol on performance deficits after intracerebroventricular administration of the excitotoxin, kainic acid, using paradigms for contextual and cued fear conditioning and spatial reversal learning in rats. The effects of three doses of quetiapine (5, 10 and 20 mg/kg) and single doses of risperidone (0.5 mg/kg) and haloperidol (0.15 mg/kg) were compared. Quetiapine administration at the lowest dose (5 mg/kg) reversed deficits in contextual and cued fear conditioning, but not deficits in spatial reversal learning, in kainic acid-treated animals. However, the two higher doses of quetiapine, and the single doses of risperidone and haloperidol, did not reverse any of the kainic acid-induced behavioral deficits. These results may be relevant to the effects of quetiapine and other antipsychotic drugs on memory deficits in patients with schizophrenia.
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Affiliation(s)
- Maureen V Martin
- Department of Psychiatry (Box 8134), Washington University School of Medicine, 660 S. Euclid, St. Louis, MO 63110, United States
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Ellenbroek BA, de Bruin NMWJ, van Den Kroonenburg PTJM, van Luijtelaar ELJM, Cools AR. The effects of early maternal deprivation on auditory information processing in adult Wistar rats. Biol Psychiatry 2004; 55:701-7. [PMID: 15038998 DOI: 10.1016/j.biopsych.2003.10.024] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Revised: 10/28/2003] [Accepted: 10/30/2003] [Indexed: 11/17/2022]
Abstract
BACKGROUND There is now ample evidence that schizophrenia is due to an interaction between genetic and (early) environmental factors which disturbs normal development of the central nervous system and ultimately leads to the development of clinical symptoms. Recently, we showed that a single 24-hour period of maternal deprivation of rat pups at postnatal day 9 leads to a disturbance in prepulse inhibition, similar to what is seen in schizophrenia. The present set of experiments was designed to further characterize the information processing deficits of maternally deprived Wistar rats. METHODS Wistar rats were deprived from their mother for 24 hours on postnatal day 9. At adult age, rats were tested in the acoustic startle paradigm for prepulse inhibition and startle habituation. Rats were also tested in the evoked potentials paradigm for auditory sensory gating. RESULTS The results show that maternal deprivation led to a reduction in acoustic startle habituation and auditory sensory gating in adult rats. Moreover, maternal deprivation disrupted prepulse inhibition but only when the prepulses were given shortly (50-100 milliseconds) before the startle stimulus. At longer intervals (250-1000 milliseconds), no effect was seen. CONCLUSIONS The implications for the model and the development of disturbances in information processes are discussed.
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Affiliation(s)
- Bart A Ellenbroek
- Department of Psychoneuropharmacology, Nijmegen Institute for Cognition and Information, Nijmegen, The Netherlands
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9
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Weitemier AZ, Ryabinin AE. Subregion-specific differences in hippocampal activity between Delay and Trace fear conditioning: an immunohistochemical analysis. Brain Res 2004; 995:55-65. [PMID: 14644471 DOI: 10.1016/j.brainres.2003.09.054] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Lesions of the hippocampus attenuate acquisition of the tone-shock contingency in Trace, but not in Delay fear conditioning. These findings suggest that hippocampal regions are differentially involved in these two forms of fear conditioning. The present study was aimed at testing the hypothesis that hippocampal neurons are differentially activated during acquisition and retrieval of Delay versus Trace fear conditioning. Male C57BL/6J mice were exposed to eight tone-shock pairings (in Trace conditioning the shock came 30 s after the tone), and tested for immobility upon reexposure to contextual stimuli or to one tone presentation. Ten brain regions were analyzed by immunohistochemistry for inducible transcription factors (ITF) c-Fos and Zif268 1.5 h after training, context test or tone test. Acquisition of both Delay and Trace fear conditioning produced significant induction of c-Fos in the majority of brain regions analyzed compared to naive control animals. Importantly, Delay fear conditioning caused a higher increase of c-Fos expression in the CA3 region of the hippocampus compared to Trace-trained animals. After cue reexposure, Zif268 levels in the dentate gyrus of the hippocampus were higher in Trace-conditioned than in Delay-conditioned animals. In addition, reexposure-related c-Fos expression in the anterior cingulate cortex was significantly higher in Delay-conditioned animals than in Trace-conditioned animals. The present study confirms differential activation of hippocampal subregions in Delay and Trace fear conditioning.
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Affiliation(s)
- Adam Z Weitemier
- Department of Behavioral Neuroscience, L470, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA.
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Abstract
Cognitive impairments are among the most common neuropsychiatric sequelae of traumatic brain injury at all levels of severity. Cerebral cholinergic neurons and their ascending projections are particularly vulnerable to acute and chronic traumatically mediated dysfunction. In light of the important role of acetylcholine in arousal, attention, memory, and other aspects of cognition, cerebral cholinergic systems contribute to and may also be a target for pharmacologic remediation among individuals with post-traumatic cognitive impairments. This article will review the evidence in support of this hypothesis. Evidence of relatively selective damage to cholinergic injury, the development of persistent anticholinergic sensitivity, and the effects of cholinergic augmentation on memory performance are presented first. Thereafter, neuropathologic, electrophysiologic, and pharmacologic evidence of cholinergic dysfunction after traumatic brain injury in humans is reviewed. Finally, future directions for investigation of the cholinergic hypothesis and possible clinical applications of this information are discussed.
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Affiliation(s)
- David B Arciniegas
- Brain Injury Rehabilitation Unit, Spalding Rehabilitation Hospital, Aurora, CO 80011, USA.
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Abstract
Schizophrenia is a common and debilitating illness, characterized by chronic psychotic symptoms and psychosocial impairment that exact considerable human and economic costs. The literature in electronic databases as well as citations and major articles are reviewed with respect to the phenomenology, pathology, treatment, genetics and neurobiology of schizophrenia. Although studied extensively from a clinical, psychological, biological and genetic perspective, our expanding knowledge of schizophrenia provides only an incomplete understanding of this complex disorder. Recent advances in neuroscience have allowed the confirmation or refutation of earlier findings in schizophrenia, and permit useful comparisons between the different levels of organization from which the illness has been studied. Schizophrenia is defined as a clinical syndrome that may include a collection of diseases that share a common presentation. Genetic factors are the most important in the etiology of the disease, with unknown environmental factors potentially modulating the expression of symptoms. Schizophrenia is a complex genetic disorder in which many genes may be implicated, with the possibility of gene-gene interactions and a diversity of genetic causes in different families or populations. A neurodevelopmental rather than degenerative process has received more empirical support as a general explanation of the pathophysiology, although simple dichotomies are not particularly helpful in such a complicated disease. Structural brain changes are present in vivo and post-mortem, with both histopathological and imaging studies in overall agreement that the temporal and frontal lobes of the cerebral cortex are the most affected. Functional imaging, neuropsychological testing and clinical observation are also generally consistent in demonstrating deficits in cognitive ability that correlate with abnormalities in the areas of the brain with structural abnormalities. The dopamine and other neurotransmitter systems are certainly involved in the treatment or modulation of psychotic symptoms. These broad findings represent the distillation of a large body of disparate data, but firm and specific findings are sparse, and much about schizophrenia remains unknown.
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Affiliation(s)
- Albert Hung Choy Wong
- Centre for Addiction and Mental Health, 250 College Street, M5T 1R8, Toronto, Ont., Canada.
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Yin H, Bardgett ME, Csernansky JG. Kainic acid lesions disrupt fear-mediated memory processing. Neurobiol Learn Mem 2002; 77:389-401. [PMID: 11991765 DOI: 10.1006/nlme.2001.4037] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous research has shown that hippocampal lesions impair the expression of fear conditioning. This fear conditioning deficit may be due to memory impairment or a reduction in fear in lesioned animals. To address these possibilities, the authors examined unconditioned and conditioned fear in male Sprague-Dawley rats that had received intracerebroventricular (ICV) infusions of kainic acid (KA) 30 days prior to testing. Animals that had received bilateral ICV infusions of KA (1.0 microl of 0.8 mg/ml solution per side) exhibited cell loss that was primarily confined to the CA3 region of the dorsal hippocampus. Kainic acid lesions impaired contextual and cued fear conditioning but did not affect unconditioned fear in a light:dark test of anxiety. Moreover, animals with KA lesions did not habituate to the light:dark apparatus when tested over a 3-day period. These data suggest that decreases in fear conditioning produced by hippocampal lesions reflect a memory deficit and not a lack of fear.
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Affiliation(s)
- Henry Yin
- Department of Psychology, Northern Kentucky University, BEP 359, Nunn Drive, Highland Heights, KY 41099, USA.
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de Bruin NM, Ellenbroek BA, van Schaijk WJ, Cools AR, Coenen AM, van Luijtelaar EL. Sensory gating of auditory evoked potentials in rats: effects of repetitive stimulation and the interstimulus interval. Biol Psychol 2001; 55:195-213. [PMID: 11240214 DOI: 10.1016/s0301-0511(00)00084-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In the P50 gating or conditioning-testing (C-T) paradigm, the P50 response, a small positive midlatency ( approximately 50 ms after stimulus onset) component of the human auditory evoked potential (AEP), is reduced towards the second click (S2) as compared to the response to the first click (S1). This phenomenon is called sensory gating. The putative function of sensory gating is thought to protect subjects from being flooded by irrelevant stimuli. Comparative studies have been done in rats in order to elucidate the underlying neural substrate of sensory gating. However, for a direct comparison of rat and human AEP components, it is imperative for both components to show similar characteristics. The amount of sensory gating in humans is dependent on repetitive stimulation and the interstimulus interval (ISI). In the present study effects of repetitive stimulation (Experiment 1) and various ISIs (Experiment 2) were determined on rat AEP components. The results demonstrate that gating is not limited to a restricted cortical area or a single midlatency component and that repetitive stimulation and ISI affect gating of several rat AEP components. Components such as the vertex P17 and N22 show a decrease in gating within several S1-S2 presentations, mainly due to a decrease in amplitude to S1 (Experiment 1). Gating for vertex components (such as the P17, N22 and N50) is ISI dependent (Experiment 2), but there is no interval in the 200-600 ms range at which optimal gating occurs. The ISI effects on gating are due to an increase of the amplitude to S2. The results have implications for the discussion about the rat homologue of the human P50.
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Affiliation(s)
- N M de Bruin
- NICI/Department of Psychoneuropharmacology, University of Nijmegen, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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14
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Abstract
Prepulse Inhibition (PPI) of the startle response and the P50 auditory-evoked potential suppression are used to assess impairments in the regulation of the neural substrates and to determine the clinical significance of inhibitory deficits in schizophrenia. The study of gating deficits in schizophrenia and in related animal model studies have already advanced our understanding of the neural substrates of information processing abnormalities in patients with schizophrenia. Individuals with schizotypal personality disorder as well as clinically unaffected family members of patients with schizophrenia show PPI and P50 suppression deficits. These "schizophrenic spectrum" populations are not grossly psychotic, nor are they receiving antipsychotic medications. Therefore, the gating deficits are presumed to reflect core (eg, intermediate phenotypic) schizophrenia-linked information processing abnormalities. Several studies have reported that gating deficits are associated with clinical ratings of psychiatric symptoms, thought disorder, and neuropsychologic deficits in patients with schizophrenia. In addition, recent human pharmacologic studies have indicated that gating deficits can be reversed by rationally-selected compounds. Animal model studies have generally shown convergence with the human studies and may lead to improved identification of efficacious new antipsychotic medications for patients with schizophrenia.
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Affiliation(s)
- G A Light
- Department of Psychiatry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0804, USA
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15
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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: 61] [Impact Index Per Article: 2.4] [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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Arciniegas D, Adler L, Topkoff J, Cawthra E, Filley CM, Reite M. Attention and memory dysfunction after traumatic brain injury: cholinergic mechanisms, sensory gating, and a hypothesis for further investigation. Brain Inj 1999; 13:1-13. [PMID: 9972437 DOI: 10.1080/026990599121827] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Traumatic brain injury (TBI) is a common occurrence, with a rate of nearly 400,000 new injuries per year. Cognitive and emotional disturbances may become persistent and disabling for many injured persons, and frequently involve symptomatic impairment in attention and memory. Impairments in attention and memory have been well characterized in TBI, and are likely related to disruption of cholinergic functioning in the hippocampus. Additionally, disturbances in this neurotransmitter system may also account for disturbances in sensory gating and discriminative attention in this population. The electroencephalographic P50 waveform of the evoked response to paired auditory stimuli may provide a physiologic market of impaired sensory gating among TBI survivors. The first application of this recording assessment to the TBI population is reported. Preliminary findings in three cases are presented, and the interpretation of impaired sensory gating in this population is discussed. Given the impact of TBI on cholinergic systems, the effects of cholinergic augmentation on attention and memory impairment, and the availability of an electrophysiologic marker of cholinergic dysfunction responsive to cholinergic agents, a testable cholinergic hypothesis for investigation and treatment of these patients is proposed.
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Affiliation(s)
- D Arciniegas
- Department of Psychiatry, University of Colorado Health Sciences Center, Denver, USA
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