1
|
Dogra S, Stansley BJ, Xiang Z, Qian W, Gogliotti RG, Nicoletti F, Lindsley CW, Niswender CM, Joffe ME, Conn PJ. Activating mGlu 3 Metabotropic Glutamate Receptors Rescues Schizophrenia-like Cognitive Deficits Through Metaplastic Adaptations Within the Hippocampus. Biol Psychiatry 2021; 90:385-398. [PMID: 33965197 PMCID: PMC8403106 DOI: 10.1016/j.biopsych.2021.02.970] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/08/2021] [Accepted: 02/08/2021] [Indexed: 12/26/2022]
Abstract
BACKGROUND Polymorphisms in GRM3, the gene encoding the mGlu3 metabotropic glutamate receptor, are associated with impaired cognition and neuropsychiatric disorders such as schizophrenia. Limited availability of selective genetic and molecular tools has hindered progress in developing a clear understanding of the mechanisms through which mGlu3 receptors regulate synaptic plasticity and cognition. METHODS We examined associative learning in mice with trace fear conditioning, a hippocampal-dependent learning task disrupted in patients with schizophrenia. Underlying cellular mechanisms were assessed using ex vivo hippocampal slice preparations with selective pharmacological tools and selective genetic deletion of mGlu3 receptor expression in specific neuronal subpopulations. RESULTS mGlu3 receptor activation enhanced trace fear conditioning and reversed deficits induced by subchronic phencyclidine. Mechanistic studies revealed that mGlu3 receptor activation induced metaplastic changes, biasing afferent stimulation to induce long-term potentiation through an mGlu5 receptor-dependent, endocannabinoid-mediated, disinhibitory mechanism. Selective genetic deletion of either mGlu3 or mGlu5 from hippocampal pyramidal cells eliminated effects of mGlu3 activation, revealing a novel mechanism by which mGlu3 and mGlu5 interact to enhance cognitive function. CONCLUSIONS These data demonstrate that activation of mGlu3 receptors in hippocampal pyramidal cells enhances hippocampal-dependent cognition in control and impaired mice by inducing a novel form of metaplasticity to regulate circuit function, providing a clear mechanism through which genetic variation in GRM3 can contribute to cognitive deficits. Developing approaches to positively modulate mGlu3 receptor function represents an encouraging new avenue for treating cognitive disruption in schizophrenia and other psychiatric diseases.
Collapse
Affiliation(s)
- Shalini Dogra
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Branden J. Stansley
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Zixiu Xiang
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA
| | - Weilun Qian
- Vanderbilt University, Nashville, TN 37232, USA
| | - Rocco G. Gogliotti
- Molecular Pharmacology and Neuroscience Department, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Ferdinando Nicoletti
- IRCCS Neuromed, Pozzilli, Italy,Department of Physiology and Pharmacology, University Sapienza of Roma, Roma, Italy
| | - Craig W. Lindsley
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA,Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA,Department of Chemistry, Vanderbilt University, Nashville, TN 37232, USA
| | - Colleen M. Niswender
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA,Vanderbilt Kennedy Center, Vanderbilt University, Nashville, TN 37232, USA
| | - Max E. Joffe
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA,Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA,Correspondence to: Max E. Joffe, Ph.D., Research Instructor, Department of Pharmacology, Vanderbilt University, 12475E MRB4, Nashville, TN 37232-0697, Tel. (615) 322-6730, Fax. (615) 343-3088, , Twitter: @mejoffe; P. Jeffrey Conn, Ph.D., Lee E. Limbird Professor of Pharmacology, Warren Center for Neuroscience Drug Discovery, Vanderbilt University, 1205 Light Hall, Nashville, TN 37232-0697, Tel. (615) 936-2478, Fax. (615) 343-3088,
| | - P. Jeffrey Conn
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA,Warren Center for Neuroscience Drug Discovery, Vanderbilt University, Nashville, TN 37232, USA,Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA,Vanderbilt Kennedy Center, Vanderbilt University, Nashville, TN 37232, USA,Correspondence to: Max E. Joffe, Ph.D., Research Instructor, Department of Pharmacology, Vanderbilt University, 12475E MRB4, Nashville, TN 37232-0697, Tel. (615) 322-6730, Fax. (615) 343-3088, , Twitter: @mejoffe; P. Jeffrey Conn, Ph.D., Lee E. Limbird Professor of Pharmacology, Warren Center for Neuroscience Drug Discovery, Vanderbilt University, 1205 Light Hall, Nashville, TN 37232-0697, Tel. (615) 936-2478, Fax. (615) 343-3088,
| |
Collapse
|
2
|
Optogenetic inhibition of ventral hippocampal neurons alleviates associative motor learning dysfunction in a rodent model of schizophrenia. PLoS One 2019; 14:e0227200. [PMID: 31891640 PMCID: PMC6938361 DOI: 10.1371/journal.pone.0227200] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 12/14/2019] [Indexed: 12/23/2022] Open
Abstract
Schizophrenia (SZ) is a serious and incurable mental disorder characterized by clinical manifestations of positive and negative symptoms and cognitive dysfunction. High-frequency deep brain stimulation (DBS) of the ventral hippocampus (VHP) has been recently applied as a therapeutic approach for SZ in both experimental and clinical studies. However, little is known about the precise mechanism of VHP-DBS treatment for SZ and the role of hippocampal cell activation in the pathogenesis of SZ. With optogenetic technology in this study, we tried to inhibit neuronal activity in the VHP which has dense projections to the prefrontal cortex, before measuring long stumulus-induced delay eyeblink conditioning (long-dEBC) in a rodent model of SZ. Rats were administrated with phencyclidine (PCP, 3 mg/kg, 1/d, ip) for successive 7 days before optogenetic intervention. The current data show that PCP administration causes significant impairment in the acquisition and timing of long-dEBC; the inhibition of bilateral VHP neurons alleviates the decreased acquisition and impaired timing of longd-dEBC in PCP-administered rats. The results provide direct evidence at the cellular level that the inhibition of VHP neuronal cells may be a prominent effect of hippocampal DBS intervention, and increased activity in the hippocampal network play a pivotal role in SZ.
Collapse
|
3
|
Burhans LB, Smith-Bell CA, Schreurs BG. Propranolol produces short-term facilitation of extinction in a rabbit model of post-traumatic stress disorder. Neuropharmacology 2018; 135:386-398. [PMID: 29578033 DOI: 10.1016/j.neuropharm.2018.03.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 03/16/2018] [Accepted: 03/22/2018] [Indexed: 10/17/2022]
Abstract
Post-traumatic stress disorder (PTSD) is a learning-based anxiety disorder with significant public health challenges due to difficulties in treating the complex, multiple symptomology. We have developed an animal model of PTSD, based on Pavlovian eyeblink conditioning in rabbits, that addresses two key features: conditioned responses (CRs) to cues associated with an aversive event and a form of conditioned hyperarousal referred to as conditioning-specific reflex modification (CRM). We have found previously that unpaired extinction is ideal for reducing both CRs and CRM simultaneously and shows sensitivity to systemic serotonergic and glutamatergic manipulations. The following study aimed to extend our work to examine the role of the noradrenergic system, dysregulation of which is strongly implicated as part of the neurobiology of PTSD and which may also play a role in the balance shift from fear reconsolidation to extinction during treatment. The goal of the following two studies was to examine whether the β-adrenergic receptor antagonist propranolol combined with either a full or brief course of unpaired extinction treatment could enhance extinction of CRs and/or CRM. Results showed a within-session facilitation of propranolol on extinction of CRs, particularly during the first extinction session, and a short-term enhancement of extinction of CRM when extinction treatment was brief. However, neither benefit translated to long-term extinction retention for the majority of subjects. Findings suggest that propranolol may provide the most therapeutic benefit in situations of high arousal early in treatment, which may be more important for future patient compliance rather than long-term treatment outcomes.
Collapse
Affiliation(s)
- Lauren B Burhans
- Blanchette Rockefeller Neurosciences Institute, Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA.
| | - Carrie A Smith-Bell
- Blanchette Rockefeller Neurosciences Institute, Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Bernard G Schreurs
- Blanchette Rockefeller Neurosciences Institute, Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| |
Collapse
|
4
|
Cicchese JJ, Berry SD. Hippocampal Non-Theta-Contingent Eyeblink Classical Conditioning: A Model System for Neurobiological Dysfunction. Front Psychiatry 2016; 7:1. [PMID: 26903886 PMCID: PMC4751249 DOI: 10.3389/fpsyt.2016.00001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/01/2016] [Indexed: 11/30/2022] Open
Abstract
Typical information processing is thought to depend on the integrity of neurobiological oscillations that may underlie coordination and timing of cells and assemblies within and between structures. The 3-7 Hz bandwidth of hippocampal theta rhythm is associated with cognitive processes essential to learning and depends on the integrity of cholinergic, GABAergic, and glutamatergic forebrain systems. Since several significant psychiatric disorders appear to result from dysfunction of medial temporal lobe (MTL) neurochemical systems, preclinical studies on animal models may be an important step in defining and treating such syndromes. Many studies have shown that the amount of hippocampal theta in the rabbit strongly predicts the acquisition rate of classical eyeblink conditioning and that impairment of this system substantially slows the rate of learning and attainment of asymptotic performance. Our lab has developed a brain-computer interface that makes eyeblink training trials contingent upon the explicit presence or absence of hippocampal theta. The behavioral benefit of theta-contingent training has been demonstrated in both delay and trace forms of the paradigm with a two- to fourfold increase in learning speed over non-theta states. The non-theta behavioral impairment is accompanied by disruption of the amplitude and synchrony of hippocampal local field potentials, multiple-unit excitation, and single-unit response patterns dependent on theta state. Our findings indicate a significant electrophysiological and behavioral impact of the pretrial state of the hippocampus that suggests an important role for this MTL system in associative learning and a significant deleterious impact in the absence of theta. Here, we focus on the impairments in the non-theta state, integrate them into current models of psychiatric disorders, and suggest how improvement in our understanding of neurobiological oscillations is critical for theories and treatment of psychiatric pathology.
Collapse
Affiliation(s)
- Joseph J Cicchese
- Department of Psychology, Center for Neuroscience, Miami University , Oxford, OH , USA
| | - Stephen D Berry
- Department of Psychology, Center for Neuroscience, Miami University , Oxford, OH , USA
| |
Collapse
|
5
|
Nees F, Heinrich A, Flor H. A mechanism-oriented approach to psychopathology: The role of Pavlovian conditioning. Int J Psychophysiol 2015; 98:351-364. [DOI: 10.1016/j.ijpsycho.2015.05.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/01/2015] [Accepted: 05/06/2015] [Indexed: 01/19/2023]
|
6
|
Role of the Neuregulin Signaling Pathway in Nicotine Dependence and Co-morbid Disorders. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 124:113-31. [PMID: 26472527 DOI: 10.1016/bs.irn.2015.07.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Smoking is currently the leading cause of preventable death in the United States and is responsible for over four million deaths annually worldwide. Therefore, there is a vast clinical unmet need with regards to therapeutics targeting smoking cessation. This is even more apparent when examining smokers co-morbid with psychiatric illness, as rates of smoking in this population are ~4× higher than in the general population. Examining common genetic and molecular signaling pathways impinging upon both smoking behavior and psychiatric illness will lead to a better understanding of co-morbid disorders and potential development of novel therapeutics. Studies have implicated the Neuregulin Signaling Pathway in the pathophysiology of a number of psychiatric illnesses. Additionally, recent studies have also shown an association between the Neuregulin Signaling Pathway and smoking behaviors. This review outlines basic mechanisms of the Neuregulin Signaling Pathway and how it may be exploited for precision medicine approaches in treating nicotine dependence and mental illness.
Collapse
|
7
|
Reeb-Sutherland BC, Fox NA. Eyeblink conditioning: a non-invasive biomarker for neurodevelopmental disorders. J Autism Dev Disord 2015; 45:376-94. [PMID: 23942847 DOI: 10.1007/s10803-013-1905-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eyeblink conditioning (EBC) is a classical conditioning paradigm typically used to study the underlying neural processes of learning and memory. EBC has a well-defined neural circuitry, is non-invasive, and can be employed in human infants shortly after birth making it an ideal tool to use in both developing and special populations. In addition, abnormalities in the cerebellum, a region of the brain highly involved in EBC, have been implicated in a number of neurodevelopmental disorders including autism spectrum disorders (ASDs). In the current paper, we review studies that have employed EBC as a biomarker for several neurodevelopmental disorders including fetal alcohol syndrome, Down syndrome, fragile X syndrome, attention deficit/hyperactivity disorder, dyslexia, specific language impairment, and schizophrenia. In addition, we discuss the benefits of using such a tool in individuals with ASD.
Collapse
Affiliation(s)
- Bethany C Reeb-Sutherland
- Department of Psychology, DM 256, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA,
| | | |
Collapse
|
8
|
Kent JS, Bolbecker AR, O'Donnell BF, Hetrick WP. Eyeblink Conditioning in Schizophrenia: A Critical Review. Front Psychiatry 2015; 6:146. [PMID: 26733890 PMCID: PMC4683521 DOI: 10.3389/fpsyt.2015.00146] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2015] [Accepted: 09/22/2015] [Indexed: 12/15/2022] Open
Abstract
There is accruing evidence of cerebellar abnormalities in schizophrenia. The theory of cognitive dysmetria considers cerebellar dysfunction a key component of schizophrenia. Delay eyeblink conditioning (EBC), a cerebellar-dependent translational probe, is a behavioral index of cerebellar integrity. The circuitry underlying EBC has been well characterized by non-human animal research, revealing the cerebellum as the essential circuitry for the associative learning instantiated by this task. However, there have been persistent inconsistencies in EBC findings in schizophrenia. This article thoroughly reviews published studies investigating EBC in schizophrenia, with an emphasis on possible effects of antipsychotic medication and stimulus and analysis parameters on reports of EBC performance in schizophrenia. Results indicate a consistent finding of impaired EBC performance in schizophrenia, as measured by decreased rates of conditioning, and that medication or study design confounds do not account for this impairment. Results are discussed within the context of theoretical and neurochemical models of schizophrenia.
Collapse
Affiliation(s)
- Jerillyn S Kent
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Minneapolis Veterans Affairs Health Care System, Minneapolis, MN, USA
| | - Amanda R Bolbecker
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA; Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
| | - Brian F O'Donnell
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA; Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
| | - William P Hetrick
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN, USA; Larue D. Carter Memorial Hospital, Indianapolis, IN, USA
| |
Collapse
|
9
|
Bernard JA, Mittal VA. Cerebellar-motor dysfunction in schizophrenia and psychosis-risk: the importance of regional cerebellar analysis approaches. Front Psychiatry 2014; 5:160. [PMID: 25505424 PMCID: PMC4243486 DOI: 10.3389/fpsyt.2014.00160] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 10/25/2014] [Indexed: 12/21/2022] Open
Abstract
Motor abnormalities in individuals with schizophrenia and those at-risk for psychosis are well documented. An accumulating body of work has also highlighted motor abnormalities related to cerebellar dysfunction in schizophrenia including eye-blink conditioning, timing, postural control, and motor learning. We have also recently found evidence for motor dysfunction in individuals at ultra high-risk for psychosis (1-3). This is particularly relevant as the cerebellum is thought to be central to the cognitive dysmetria model of schizophrenia, and these overt motor signs may point to more general cerebellar dysfunction in the etiology of psychotic disorders. While studies have provided evidence indicative of motor cerebellar dysfunction in at-risk populations and in schizophrenia, findings with respect to the cerebellum have been mixed. One factor potentially contributing to these mixed results is the whole-structure approach taken when investigating the cerebellum. In non-human primates, there are distinct closed-loop circuits between the cerebellum, thalamus, and brain with motor and non-motor cortical regions. Recent human neuroimaging has supported this finding and indicates that there is a cerebellar functional topography (4), and this information is being missed with whole-structure approaches. Here, we review cerebellar-motor dysfunction in individuals with schizophrenia and those at-risk for psychosis. We also discuss cerebellar abnormalities in psychosis, and the cerebellar functional topography. Because of the segregated functional regions of the cerebellum, we propose that it is important to look at the structure regionally in order to better understand its role in motor dysfunction in these populations. This is analogous to approaches taken with the basal ganglia, where each region is considered separately. Such an approach is necessary to better understand cerebellar pathophysiology on a macro-structural level with respect to the pathogenesis of psychosis.
Collapse
Affiliation(s)
- Jessica A Bernard
- Department of Psychology and Neuroscience, University of Colorado Boulder , Boulder, CO , USA
| | - Vijay A Mittal
- Department of Psychology and Neuroscience, University of Colorado Boulder , Boulder, CO , USA ; Center for Neuroscience, University of Colorado Boulder , Boulder, CO , USA
| |
Collapse
|
10
|
Testing long-term memory in animal models of schizophrenia: Suggestions from CNTRICS. Neurosci Biobehav Rev 2013; 37:2141-8. [DOI: 10.1016/j.neubiorev.2013.06.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 04/30/2013] [Accepted: 06/10/2013] [Indexed: 12/27/2022]
|
11
|
Forsyth JK, Bolbecker AR, Mehta CS, Klaunig MJ, Steinmetz JE, O'Donnell BF, Hetrick WP. Cerebellar-dependent eyeblink conditioning deficits in schizophrenia spectrum disorders. Schizophr Bull 2012; 38:751-9. [PMID: 21148238 PMCID: PMC3406528 DOI: 10.1093/schbul/sbq148] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Accumulating evidence suggests that abnormalities in neural circuitry and timing associated with the cerebellum may play a role in the pathophysiology of schizophrenia. Schizotypal personality disorder (SPD) may be genetically linked to schizophrenia, but individuals with SPD are freer from potential research confounds and may therefore offer insight into psychophysiological correlates of schizophrenia. The present study employed a delay eyeblink conditioning (EBC) procedure to examine cerebellar-dependent learning in schizophrenia, SPD, and healthy control subjects (n = 18 per group) who were matched for age and gender. The conditioned stimulus was a 400-ms tone that coterminated with a 50 ms unconditioned stimulus air puff. Cognitive performance on the Picture Completion, Digit Symbol Coding, Similarities, and Digit Span subscales of the Wechsler Adult Intelligence Scale--Third Edition was also investigated. The schizophrenia and SPD groups demonstrated robust EBC impairment relative to the control subjects; they had significantly fewer conditioned responses (CRs), as well as smaller CR amplitudes. Schizophrenia subjects showed cognitive impairment across subscales compared with SPD and control subjects; SPD subjects showed intermediate performance to schizophrenia and control subjects and performed significantly worse than controls on Picture Completion. Impaired EBC was significantly related to decreased processing speed in schizophrenia spectrum subjects. These findings support the role of altered cortico-cerebellar-thalamic-cortical circuitry in the pathophysiology of schizophrenia spectrum disorders.
Collapse
Affiliation(s)
- Jennifer K. Forsyth
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN
| | - Amanda R. Bolbecker
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN
| | - Crystal S. Mehta
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN
| | - Mallory J. Klaunig
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN
| | | | - Brian F. O'Donnell
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN,Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN
| | - William P. Hetrick
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405,Larue D. Carter Memorial Hospital, Indianapolis, IN,Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN,To whom correspondence should be addressed; tel: 812-855-2620, fax: 812-855-4544, e-mail:
| |
Collapse
|
12
|
Bolbecker AR, Steinmetz AB, Mehta CS, Forsyth JK, Klaunig MJ, Lazar EK, Steinmetz JE, O'Donnell BF, Hetrick WP. Exploration of cerebellar-dependent associative learning in schizophrenia: effects of varying and shifting interstimulus interval on eyeblink conditioning. Behav Neurosci 2012; 125:687-98. [PMID: 21942432 DOI: 10.1037/a0025150] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Eyeblink conditioning abnormalities have been reported in schizophrenia, but the extent to which these anomalies are evident across a range of delay intervals (i.e., interstimulus intervals; ISIs) is unknown. In addition, the effects of ISI shifts on learning are unknown, though such manipulations can be informative about the plasticity of cerebellar timing functions. Therefore, the primary purpose of the present study was to investigate the interactions between ISI manipulations and learning in schizophrenia. A standard delay eyeblink conditioning procedure with four different interstimulus intervals (ISIs; 250, 350, 550, 850 ms) was employed. Each eyeblink conditioning experiment was immediately followed by another with a different ISI, thus permitting the characterization of conditioned response (CR) learning at one ISI and the extent to which CRs could be generated at a different latency following an ISI shift. Collapsing across all conditions, the schizophrenia group (n = 55) had significantly fewer conditioned responses and longer onset latencies than age-matched controls (n = 55). Surprisingly, shifting to a new ISI had negligible effects on conditioned response rates in both groups. These findings contribute to evidence of robust eyeblink conditioning abnormalities in schizophrenia and suggest impaired cerebellar function, but underscore the need for more research to clarify the source of these abnormalities and their relationship to clinical manifestations of schizophrenia.
Collapse
Affiliation(s)
- Amanda R Bolbecker
- Department of Psychological and Brain Sciences, Indiana University Bloomington, IN 47405, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Associative learning and the genetics of schizophrenia. Trends Neurosci 2009; 32:359-65. [DOI: 10.1016/j.tins.2009.01.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 01/19/2009] [Accepted: 01/20/2009] [Indexed: 02/05/2023]
|
14
|
Eye-blink conditioning deficits indicate temporal processing abnormalities in schizophrenia. Schizophr Res 2009; 111:182-91. [PMID: 19351577 PMCID: PMC2702657 DOI: 10.1016/j.schres.2009.03.016] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 02/24/2009] [Accepted: 03/02/2009] [Indexed: 11/22/2022]
Abstract
Theoretical models suggest that symptoms of schizophrenia may be due to a dysfunctional modulatory system associated with the cerebellum. Although it has long been known that the cerebellum plays a critical role in associative learning and motor timing, recent evidence suggests that it also plays a role in nonmotor psychological processes. Indeed, cerebellar anomalies in schizophrenia have been linked to cognitive dysfunction and poor long-term outcome. To test the hypothesis that schizophrenia is associated with cerebellar dysfunction, cerebellar-dependent, delay eye-blink conditioning was examined in 62 individuals with schizophrenia and 62 age-matched non-psychiatric comparison subjects. The conditioned stimulus was a 400 ms tone, which co-terminated with a 50 ms unconditioned stimulus air puff. A subset of participants (25 with schizophrenia and 29 controls) also completed the Wechsler Abbreviated Scale of Intelligence. Participants with schizophrenia exhibited lower rates of eye-blink conditioning, including earlier (less adaptively timed) conditioned response latencies. Cognitive functioning was correlated with the rate of conditioned responsing in the non-psychiatric comparison subjects but not among those with schizophrenia, and the magnitude of these correlations significantly differed between groups. These findings are consistent with models of schizophrenia in which disruptions within the cortico-cerebellar-thalamic-cortical (CCTC) brain circuit are postulated to underlie the cognitive fragmentation that characterizes the disorder.
Collapse
|
15
|
Activation of the maternal immune system alters cerebellar development in the offspring. Brain Behav Immun 2009; 23:116-23. [PMID: 18755264 PMCID: PMC2614890 DOI: 10.1016/j.bbi.2008.07.012] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 07/19/2008] [Accepted: 07/29/2008] [Indexed: 11/23/2022] Open
Abstract
A common pathological finding in autism is a localized deficit in Purkinje cells (PCs). Cerebellar abnormalities have also been reported in schizophrenia. Using a mouse model that exploits a known risk factor for these disorders, maternal infection, we asked if the offspring of pregnant mice given a mid-gestation respiratory infection have cerebellar pathology resembling that seen in these disorders. We also tested the effects of maternal immune activation in the absence of virus by injection of the synthetic dsRNA, poly(I:C). We infected pregnant mice with influenza on embryonic day 9.5 (E9.5), or injected poly(I:C) i.p. on E12.5, and assessed the linear density of PCs in the cerebellum of adult or postnatal day 11 (P11) offspring. To study granule cell migration, we also injected BrdU on P11. Adult offspring of influenza- or poly(I:C)-exposed mice display a localized deficit in PCs in lobule VII of the cerebellum, as do P11 offspring. Coincident with this are heterotopic PCs, as well as delayed migration of granule cells in lobules VI and VII. The cerebellar pathology observed in the offspring of influenza- or poly(I:C)-exposed mice is strikingly similar to that observed in autism. The poly(I:C) findings indicate that deficits are likely caused by the activation of the maternal immune system. Finally, our data suggest that cerebellar abnormalities occur during embryonic development, and may be an early deficit in autism and schizophrenia.
Collapse
|
16
|
Cerebellum volume and eyeblink conditioning in schizophrenia. Psychiatry Res 2008; 162:185-94. [PMID: 18222655 PMCID: PMC2366060 DOI: 10.1016/j.pscychresns.2007.06.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 03/30/2007] [Accepted: 06/04/2007] [Indexed: 10/22/2022]
Abstract
Although accumulating evidence suggests that cerebellar abnormalities may be linked to the symptoms and course of schizophrenia, few studies have related structural and functional indices of cerebellar integrity. The present study examined the relationship between the volume of specific subregions of the cerebellum and cerebellar function, as measured by eyeblink conditioning (EBC). Nine individuals with schizophrenia and six healthy comparison participants completed structural magnetic resonance imaging of the brain and a delay EBC procedure. Volumetric measurements were taken for the whole brain, whole cerebellum, cerebellar anterior lobules I-V and posterior lobules VI-VII. The schizophrenia group had smaller cerebellar anterior lobes and exhibited impaired EBC relative to the comparison group. In the comparison group, larger anterior volume correlated with earlier conditioned response onset latencies and increased amplitudes of the unconditioned blink response during paired trials (i.e., when the conditioned and unconditioned stimuli co-occurred). The findings that smaller anterior cerebellar volumes and EBC impairments were associated with schizophrenia are consistent with non-human studies showing that anterior cerebellar abnormalities are associated with deficits in delay EBC. The lack of a significant correlation between indices of EBC and cerebellar volume within the schizophrenia group suggests an aberrant relationship between cerebellar structure and function.
Collapse
|
17
|
Gerdjikov TV, Rudolph U, Keist R, Möhler H, Feldon J, Yee BK. Hippocampal α5 subunit-containing GABAA receptors are involved in the development of the latent inhibition effect. Neurobiol Learn Mem 2008; 89:87-94. [PMID: 17638582 DOI: 10.1016/j.nlm.2007.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2007] [Revised: 06/05/2007] [Accepted: 06/06/2007] [Indexed: 10/23/2022]
Abstract
Hippocampal GABA(A) receptors containing the alpha 5 subunit have been implicated in the modulation of hippocampal-dependent learning, presumably via their tonic inhibitory influence on hippocampal glutamatergic activity. Here, we examined the expression of latent inhibition (LI)--a form of selective learning that is sensitive to a number of manipulations targeted at the hippocampal formation, in alpha 5(H105R) mutant mice with reduced levels of hippocampal alpha 5-containing GABA(A) receptors. A single pre-exposure to the taste conditioned stimulus (CS) prior to the pairing of the same CS with LiCl-induced nausea was effective in reducing the conditioned aversion against the taste CS in wild-type mice--thus constituting the LI effect. LI was however distinctly absent in male alpha 5(H105R) mutant mice. Hence, a partial loss of hippocampal alpha 5 GABA(A) receptors is sufficient to alter one major form of selective learning, albeit this was not seen in the female. This observed phenotype suggests that specific activation of these extrasynaptic GABA(A) receptors may confer therapeutic potential against the failure to show selectivity in learning by human psychotic patients.
Collapse
Affiliation(s)
- T V Gerdjikov
- Laboratory of Behavioral Neurobiology, ETH Zurich, Schwerzenbach, Switzerland
| | | | | | | | | | | |
Collapse
|
18
|
Dimitrova A, Gerwig M, Brol B, Gizewski ER, Forsting M, Beck A, Aurich V, Kolb FP, Timmann D. Correlation of cerebellar volume with eyeblink conditioning in healthy subjects and in patients with cerebellar cortical degeneration. Brain Res 2008; 1198:73-84. [PMID: 18262502 DOI: 10.1016/j.brainres.2008.01.034] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Revised: 12/24/2007] [Accepted: 01/03/2008] [Indexed: 11/18/2022]
Abstract
In the present study, acquisition and timing of conditioned eyeblink responses (CRs) were correlated with magnetic resonance imaging (MRI)-based cerebellar volume both in healthy human subjects and patients with cerebellar disease. Thirty-three healthy subjects and 25 patients with pure cortical cerebellar degeneration participated. Cerebellar volumes were measured for the cortex of the anterior lobe, the cortex of the posterior lobe, the white matter of the cerebellum and the cerebrum based on 3D MR images. CR parameters were assessed in a standard delay paradigm. In healthy subjects CR acquisition was significantly related to the volume of the grey matter of the posterior lobe, but neither to the volume of the grey matter of the anterior lobe, nor to the cerebellar white matter and nor to the cerebral volume. As expected, CR acquisition and volume of the cortex of the posterior lobe showed age-related decline in the controls. Furthermore, CR acquisition was significantly reduced in patients with cerebellar degeneration compared to controls. In the cerebellar group, however, no significant correlations between CR acquisition and any of the cerebellar volumes were observed. Floor effects are most likely responsible for this observation. Although CRs occurred significantly earlier in cerebellar patients compared to controls, no significant correlations between CR timing parameters and any of the cerebellar volumes were observed. Extending previous findings in healthy human subjects, age-related decline of the cerebellar cortex of the posterior lobe was related with a reduction of CR acquisition. Findings provide further evidence that the cerebellar cortex plays an important role in the acquisition of eyeblink conditioning in humans.
Collapse
Affiliation(s)
- Albena Dimitrova
- Department of Neurology, University of Duisburg-Essen, Hufelandstrasse 55, 45138 Essen, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Gerwig M, Kolb FP, Timmann D. The involvement of the human cerebellum in eyeblink conditioning. THE CEREBELLUM 2007; 6:38-57. [PMID: 17366265 DOI: 10.1080/14734220701225904] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Besides its known importance for motor coordination, the cerebellum plays a major role in associative learning. The form of cerebellum-dependent associative learning, which has been examined in greatest detail, is classical conditioning of eyeblink responses. The much advanced knowledge of anatomical correlates, as well as cellular and molecular mechanisms involved in eyeblink conditioning in animal models are of particular importance because there is general acceptance that findings in humans parallel the animal data. The aim of the present review is to give an update of findings in humans. Emphasis is put on human lesion studies, which take advantage of the advances of high-resolution structural magnetic resonance imaging (MRI). In addition, findings of functional brain imaging in healthy human subjects are reviewed. The former helped to localize areas involved in eyeblink conditioning within the cerebellum, the latter was in particular helpful in delineating extracerebellar neural substrates, which may contribute to eyeblink conditioning. Human lesion studies support the importance of cortical areas of the ipsilateral superior cerebellum both in the acquisition and timing of conditioned eyeblink responses (CR). Furthermore, the ipsilateral cerebellar cortex seems to be also important in extinction of CRs. Cortical areas, which are important for CR acquisition, overlap with areas related to the control of the unconditioned eyeblink response. Likewise, cortical lesions are followed by increased amplitudes of unconditioned eyeblinks. These findings are in good accordance with the animal literature. Knowledge about contributions of the cerebellar nuclei in humans, however, is sparse. Due to methodological limitations both of human lesion and functional MRI studies, at present no clear conclusions can be drawn on the relative contributions of the cerebellar cortex and nuclei.
Collapse
Affiliation(s)
- M Gerwig
- Department of Neurology, University of Duisburg-Essen, Hufelandstrasse 55, 45138 Essen, Germany
| | | | | |
Collapse
|
20
|
Vythilingam M, Lawley M, Collin C, Bonne O, Agarwal R, Hadd K, Charney DS, Grillon C. Hydrocortisone impairs hippocampal-dependent trace eyeblink conditioning in post-traumatic stress disorder. Neuropsychopharmacology 2006; 31:182-8. [PMID: 16123770 DOI: 10.1038/sj.npp.1300843] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Trace eyeblink conditioning is a hippocampal-dependent associative learning task that could help evaluate hippocampal function in Post-traumatic stress disorder (PTSD). Since preclinical research has demonstrated that trace eyeblink conditioning can be pharmacologically manipulated by glucocorticoids, this task may shed light on glucocorticoid sensitivity in PTSD. This study assessed baseline and hydrocortisone-mediated changes in trace eyeblink conditioning in patients with PTSD and in healthy controls. A total of 12 patients with PTSD and 12 age- and sex-matched healthy controls participated in a trace eyeblink test 6 h following intravenous administration of 30 mg of hydrocortisone. Spontaneous blink rates were similar between PTSD patients and healthy controls. There was no significant difference in the mean conditioned response between PTSD subjects and healthy controls under placebo conditions. Following hydrocortisone administration, only the PTSD patients demonstrated a significant reduction in conditioned response in contrast to healthy subjects who did not demonstrate any change. Patients with PTSD had increased glucocorticoid sensitivity in the focal brain regions mediating trace eyeblink conditioning.
Collapse
Affiliation(s)
- Meena Vythilingam
- Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD 20892-2670, USA.
| | | | | | | | | | | | | | | |
Collapse
|
21
|
Arndt TL, Stodgell CJ, Rodier PM. The teratology of autism. Int J Dev Neurosci 2005; 23:189-99. [PMID: 15749245 DOI: 10.1016/j.ijdevneu.2004.11.001] [Citation(s) in RCA: 245] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Revised: 11/22/2004] [Accepted: 11/22/2004] [Indexed: 10/25/2022] Open
Abstract
Autism spectrum disorders affect behaviors that emerge at ages when typically developing children become increasingly social and communicative, but many lines of evidence suggest that the underlying alterations in the brain occur long before the period when symptoms become obvious. Studies of the behavior of children in the first year of life demonstrate that symptoms are often detectable in the first 6 months. The environmental factors known to increase the risk of autism have critical periods of action during embryogenesis. Minor malformations that occur frequently in people with autism are known to arise in the same stages of development. Anomalies reported from histological studies of the brain are consistent with an early alteration of development. Congenital syndromes with high rates of autism include somatic that originate early in the first trimester. In addition, it is possible to duplicate a number of anatomic and behavioral features characteristic of human cases by exposing rat embryos to a teratogenic dose of valproic acid at the time of neural tube closure.
Collapse
Affiliation(s)
- Tara L Arndt
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | | | | |
Collapse
|
22
|
Chambers JS, Perrone-Bizzozero NI. Altered myelination of the hippocampal formation in subjects with schizophrenia and bipolar disorder. Neurochem Res 2005; 29:2293-302. [PMID: 15672553 DOI: 10.1007/s11064-004-7039-x] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Myelination of the frontal and temporal lobes occurs at a similar time period as symptom onset in schizophrenia. To assess this potential relationship, we compared myelination and oligodendrocyte numbers in the hippocampal formation of controls and matched subjects with schizophrenia and bipolar disorder. The levels and distribution of the myelin marker myelin basic protein (MBP) and the oligodendrocyte marker adenomatous polyposis coli (APC) were measured using immunocytochemistry. MBP immunoreactivity (IR) was increased in several hippocampal subregions of control females versus control males. Female subjects with schizophrenia and bipolar disorder exhibited decreased myelination in the hippocampal formation while male subjects with bipolar disorder showed increased MBP levels in the superior medullary lamina. In contrast, the number of APC immunoreactive cells did not differ in any disorder or region. Our results demonstrate an interaction between gender, mental illness, and myelination, and may be related to cognitive deficits seen in schizophrenia and bipolar disorder.
Collapse
Affiliation(s)
- Jessie S Chambers
- 915 Camino de Salud NE, Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
| | | |
Collapse
|
23
|
Chambers JS, Thomas D, Saland L, Neve RL, Perrone-Bizzozero NI. Growth-associated protein 43 (GAP-43) and synaptophysin alterations in the dentate gyrus of patients with schizophrenia. Prog Neuropsychopharmacol Biol Psychiatry 2005; 29:283-90. [PMID: 15694236 DOI: 10.1016/j.pnpbp.2004.11.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/19/2004] [Indexed: 11/17/2022]
Abstract
Growth-associated protein 43 (GAP-43) expression is critical for the proper establishment of neural circuitry, a process thought to be disrupted in schizophrenia. Previous work from our laboratory demonstrated decreased GAP-43 levels in post-mortem tissue from the entire hippocampal formation of affected individuals. In the present study, we used immunocytochemical techniques to localize alterations in GAP-43 protein to specific synapses. GAP-43 distribution was compared to that of synaptophysin, another synaptic protein known to be altered in schizophrenia. The levels and distribution of GAP-43 and synaptophysin proteins were measured in the dentate gyrus of subjects with schizophrenia and sex-, age-, and postmortem interval-matched normal controls and subjects with bipolar disorder. Tissue from subjects was provided by the Harvard Brain Tissue Resource Center. In control subjects, GAP-43 immunostaining was prominent in synaptic terminals in the inner molecular layer and hilar region. Subjects with schizophrenia had significant decreases in GAP-43 immunoreactivity in the hilus (p<0.05, paired t-test) and inner molecular layer (p<0.05, paired t-test) but not in the outer molecular layer. In the same tissues, synaptophysin immunoreactivity was significantly reduced in both the inner and outer molecular layers of the dentate gyrus (both p<0.01 by paired t-test), but not in the hilus. In contrast to patients with schizophrenia, GAP-43 and synaptophysin levels in subjects with bipolar disorder did not differ from controls. Given the relationship of GAP-43 and synaptophysin with the development and plasticity of synaptic connections, the observed alterations in the hippocampus of patients with schizophrenia may be related to cognitive deficits associated with this illness.
Collapse
Affiliation(s)
- Jessie S Chambers
- Department of Neurosciences, University of New Mexico School of Medicine, 915 Camino de Salud NE, Albuquerque, NM 87131, USA
| | | | | | | | | |
Collapse
|
24
|
Brown SM, Kieffaber PD, Carroll CA, Vohs JL, Tracy JA, Shekhar A, O'Donnell BF, Steinmetz JE, Hetrick WP. Eyeblink conditioning deficits indicate timing and cerebellar abnormalities in schizophrenia. Brain Cogn 2005; 58:94-108. [PMID: 15878730 DOI: 10.1016/j.bandc.2004.09.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2004] [Accepted: 09/16/2004] [Indexed: 11/22/2022]
Abstract
Accumulating evidence indicates that individuals with schizophrenia manifest abnormalities in structures (cerebellum and basal ganglia) and neurotransmitter systems (dopamine) linked to internal-timing processes. A single-cue tone delay eyeblink conditioning paradigm comprised of 100 learning and 50 extinction trials was used to examine cerebellar timing circuits in 13 medicated patients with schizophrenia and 13 age- and sex-matched controls. Patients with schizophrenia showed impaired learning of the conditioned response compared to controls and also greater within-subject variability in the timing of their responses. These findings are consistent with models of schizophrenia in which timing deficits underlie information-processing abnormalities and clinical features of the disorder.
Collapse
Affiliation(s)
- S M Brown
- Department of Psychology, Indiana University, 1101 East Tenth Street, Bloomington, IN 47405, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Timmann D, Gerwig M, Frings M, Maschke M, Kolb FP. Eyeblink conditioning in patients with hereditary ataxia: a one-year follow-up study. Exp Brain Res 2004; 162:332-45. [PMID: 15586270 DOI: 10.1007/s00221-004-2181-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 10/18/2004] [Indexed: 10/26/2022]
Abstract
Delay eyeblink conditioning was examined in patients with genetically-defined heredoataxias and age-matched control subjects. 24 patients with spinocerebellar ataxia type 6 (SCA6), type 3 (SCA3), and Friedreich's ataxia (FRDA) participated. SCA6 affects primarily the cerebellum, whereas extracerebellar involvement is common in SCA3 and FRDA. Testing was performed in three sessions six months apart. Severity of ataxia was defined based on the International Ataxia Cooperative Rating Scale (ICARS). As expected, cerebellar patients were significantly impaired in eyeblink conditioning compared to controls. Signs of retention and further learning across sessions were present in controls, but not in the cerebellar patients. In addition, findings of disturbed timing of conditioned responses were observed. Both onsets and peaks of the conditioned responses (CRs) occurred significantly earlier in cerebellar patients. Shortened CR responses were most prominent in patients with primarily cerebellar cortical disease (SCA6). In the group of all cerebellar patients, the SCA3 and the FRDA group correlations between learning deficits and clinical findings were weak. Moderate-to-strong correlations were found in the SCA6 patients. There was no significant change, however, in clinical ataxia scores and CR incidence across the three sessions. In summary, impaired learning of conditioned eyeblink responses is a stable finding across multiple sessions in patients with degenerative cerebellar disorders. Eyeblink conditioning may be a useful measure of cerebellar impairment in patients with hereditary ataxias that primarily affect the cerebellum (such as SCA6). In other heredoataxias (such as SCA3 and FRDA), extracerebellar involvement not assessed by ICARS likely contributes to eyeblink conditioning abnormalities.
Collapse
Affiliation(s)
- D Timmann
- Department of Neurology, University of Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany.
| | | | | | | | | |
Collapse
|
26
|
Grillon C, Smith K, Haynos A, Nieman LK. Deficits in hippocampus-mediated Pavlovian conditioning in endogenous hypercortisolism. Biol Psychiatry 2004; 56:837-43. [PMID: 15576060 DOI: 10.1016/j.biopsych.2004.09.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Revised: 08/23/2004] [Accepted: 09/04/2004] [Indexed: 11/20/2022]
Abstract
BACKGROUND Elevated endogenous levels of corticosteroids cause neural dysfunction and loss, especially within the hippocampus, as well as cognitive impairment in hippocampus-mediated tasks. Because Cushing's syndrome patients suffer from hypercortisolism, they represent a unique opportunity to study the impact of elevated glucocorticoids on cognitive functions. The aim of this study was to examine the performance of Cushing's syndrome patients on trace eyeblink conditioning, a cross-species, hippocampal-mediated test of learning and memory. METHODS Eleven Cushing's syndrome patients and 11 healthy control subjects participated in an eyeblink trace conditioning test (1000-msec trace) and a task of declarative memory for words. Salivary cortisol was collected in both the patients and the control subjects, and urinary free cortisol was collected in the patients only. RESULTS The patients exhibited fewer conditional responses and remembered fewer words, compared with the control subjects. Cortisol levels correlated with immediate and delayed declarative memory only. Conditional response correlated with delayed recall after controlling for the magnitude of unconditional response. CONCLUSIONS The integrity of the hippocampus seems to be compromised in Cushing's syndrome patients. Trace eyeblink conditioning might be useful both as a clinical tool to examine changes in hippocampus function in Cushing's disease patients and as a translational tool of research on the impact of chronic exposure of glucocorticoids.
Collapse
Affiliation(s)
- Christian Grillon
- Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD 20892-2670, USA.
| | | | | | | |
Collapse
|