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Dijkhuizen S, Van Ginneken LMC, IJpelaar AHC, Koekkoek SKE, De Zeeuw CI, Boele HJ. Impact of enriched environment on motor performance and learning in mice. Sci Rep 2024; 14:5962. [PMID: 38472324 PMCID: PMC10933351 DOI: 10.1038/s41598-024-56568-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 03/08/2024] [Indexed: 03/14/2024] Open
Abstract
Neuroscience heavily relies on animal welfare in laboratory rodents as it can significantly affect brain development, cognitive function and memory formation. Unfortunately, laboratory animals are often raised in artificial environments devoid of physical and social stimuli, potentially leading to biased outcomes in behavioural assays. To assess this effect, we examined the impact of social and physical cage enrichment on various forms of motor coordination. Our findings indicate that while enriched-housed animals did not exhibit faster learning in eyeblink conditioning, the peak timing of their conditioned responses was slightly, but significantly, improved. Additionally, enriched-housed animals outperformed animals that were housed in standard conditions in the accelerating rotarod and ErasmusLadder test. In contrast, we found no significant effect of enrichment on the balance beam and grip strength test. Overall, our data suggest that an enriched environment can improve motor performance and motor learning under challenging and/or novel circumstances, possibly reflecting an altered state of anxiety.
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Affiliation(s)
- S Dijkhuizen
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands
| | - L M C Van Ginneken
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands
| | - A H C IJpelaar
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands
| | - S K E Koekkoek
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands
| | - C I De Zeeuw
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands.
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA, Amsterdam, The Netherlands.
| | - H J Boele
- Department of Neuroscience, Erasmus MC, 3015 GD, Rotterdam, The Netherlands.
- Princeton Neuroscience Institute, Princeton, NJ, 08540, USA.
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2
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Allen MT. Weaker situations: Uncertainty reveals individual differences in learning: Implications for PTSD. COGNITIVE, AFFECTIVE & BEHAVIORAL NEUROSCIENCE 2023:10.3758/s13415-023-01077-5. [PMID: 36944865 DOI: 10.3758/s13415-023-01077-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/07/2023] [Indexed: 03/23/2023]
Abstract
Few individuals who experience trauma develop posttraumatic stress disorder (PTSD). Therefore, the identification of individual differences that signal increased risk for PTSD is important. Lissek et al. (2006) proposed using a weak rather than a strong situation to identify individual differences. A weak situation involves less-salient cues as well as some degree of uncertainty, which reveal individual differences. A strong situation involves salient cues with little uncertainty, which produce consistently strong responses. Results from fear conditioning studies that support this hypothesis are discussed briefly. This review focuses on recent findings from three learning tasks: classical eyeblink conditioning, avoidance learning, and a computer-based task. These tasks are interpreted as weaker learning situations in that they involve some degree of uncertainty. Individual differences in learning based on behavioral inhibition, which is a risk factor for PTSD, are explored. Specifically, behaviorally inhibited individuals and rodents (i.e., Wistar Kyoto rats), as well as individuals expressing PTSD symptoms, exhibit enhanced eyeblink conditioning. Behaviorally inhibited rodents also demonstrate enhanced avoidance responding (i.e., lever pressing). Both enhanced eyeblink conditioning and avoidance are most evident with schedules of partial reinforcement. Behaviorally inhibited individuals also performed better on reward and punishment trials than noninhibited controls in a probabilistic category learning task. Overall, the use of weaker situations with uncertain relationships may be more ecologically valid than learning tasks in which the aversive event occurs on every trial and may provide more sensitivity for identifying individual differences in learning for those at risk for, or expressing, PTSD symptoms.
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Affiliation(s)
- M Todd Allen
- School of Psychological Sciences, University of Northern Colorado, Greeley, CO, USA.
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3
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Toward an assessment of escape/avoidance coping in depression. Behav Brain Res 2020; 381:112363. [DOI: 10.1016/j.bbr.2019.112363] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 11/14/2019] [Accepted: 11/14/2019] [Indexed: 12/18/2022]
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Miller DP, Allen MT, Servatius RJ. Partial Predictability in Avoidance Acquisition and Expression of Wistar-Kyoto and Sprague-Dawley Rats: Implications for Anxiety Vulnerability in Uncertain Situations. Front Psychiatry 2020; 11:848. [PMID: 32973587 PMCID: PMC7466649 DOI: 10.3389/fpsyt.2020.00848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/04/2020] [Indexed: 11/20/2022] Open
Abstract
Individual differences or vulnerabilities must exist which bias some individuals toward psychopathology while others remain resilient in the face of trauma. Recent work has studied the effects of uncertainty on individuals expressing behavioral inhibition (BI). The current study extended this work with uncertainty to Wistar Kyoto (WKY) rats which are a behaviorally inhibited inbred strain that models learning vulnerabilities for anxiety disorders and posttraumatic stress disorder (PTSD). WKY rats exhibit superior avoidance performance in a signaled bar press avoidance task in which a tone conditioned stimulus (CS) signals a foot shock unconditional stimulus (US) when compared with non-inhibited Sprague-Dawley (SD) rats. In addition, WKY rats express enhanced eyeblink conditioning. Recent work with behaviorally inhibited humans has indicated that this enhanced eyeblink conditioning is more evident in conditions that insert CS- or US-alone trials into CS-US paired training, resulting in uncertain and suboptimal learning conditions. The current study examined the effects of partial predictability training, in which the CS signaled the US only one-half of the time, on the acquisition and expression of avoidance. Standard training with a fixed 60-s CS which predicted shock on 100% of trials was compared with training in which the CS predicted shock on 50% of trials (partial predictability) using a pseudorandom schedule. As expected, WKY rats acquired avoidance responses faster and to a greater degree than SD rats. Partial predictability of the US essentially reduced SD rats to escape responding. Partial predictability also reduced avoidance in WKY rats; however, adjusting avoidance rates for the number of potential pairings of the CS and US early in training suggested a similar degree of avoidance expression late in the last session of training. Enhanced active avoidance expression, even in uncertain learning conditions, can be interpreted as behaviorally inhibited WKY rats responding to the expectancy of the shock by avoiding, whereas non-inhibited SD rats were responding to the presence of the shock by escaping. Future work should explore how WKY and SD rats as well as behaviorally inhibited humans acquire and extinguish avoidance responses in uncertain learning situations.
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Affiliation(s)
- Daniel Paul Miller
- Neuroscience Department, Carthage College, Kenosha, WI, United States.,Department of Psychiatry, Stress and Motivated Behavior Institute, Upstate Medical University, Syracuse, NY, United States
| | - Michael Todd Allen
- Department of Psychiatry, Stress and Motivated Behavior Institute, Upstate Medical University, Syracuse, NY, United States.,School of Psychological Sciences, University of Northern Colorado, Greeley, CO, United States
| | - Richard J Servatius
- Department of Psychiatry, Stress and Motivated Behavior Institute, Upstate Medical University, Syracuse, NY, United States.,Department of Veterans Affairs, Syracuse Veterans Affairs Medical Center, Syracuse, NY, United States
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5
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Allen M, Handy J, Miller D, Servatius R. Avoidance learning and classical eyeblink conditioning as model systems to explore a learning diathesis model of PTSD. Neurosci Biobehav Rev 2019; 100:370-386. [DOI: 10.1016/j.neubiorev.2019.03.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 03/04/2019] [Accepted: 03/05/2019] [Indexed: 01/09/2023]
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6
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Allen MT, Myers CE, Beck KD, Pang KCH, Servatius RJ. Inhibited Personality Temperaments Translated Through Enhanced Avoidance and Associative Learning Increase Vulnerability for PTSD. Front Psychol 2019; 10:496. [PMID: 30967806 PMCID: PMC6440249 DOI: 10.3389/fpsyg.2019.00496] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 02/20/2019] [Indexed: 12/22/2022] Open
Abstract
Although many individuals who experience a trauma go on to develop post-traumatic stress disorder (PTSD), the rate of PTSD following trauma is only about 15-24%. There must be some pre-existing conditions that impart increased vulnerability to some individuals and not others. Diathesis models of PTSD theorize that pre-existing vulnerabilities interact with traumatic experiences to produce psychopathology. Recent work has indicated that personality factors such as behavioral inhibition (BI), harm avoidance (HA), and distressed (Type D) personality are vulnerability factors for the development of PTSD and anxiety disorders. These personality temperaments produce enhanced acquisition or maintenance of associations, especially avoidance, which is a criterion symptom of PTSD. In this review, we highlight the evidence for a relationship between these personality types and enhanced avoidance and associative learning, which may increase risk for the development of PTSD. First, we provide the evidence confirming a relationship among BI, HA, distressed (Type D) personality, and PTSD. Second, we present recent findings that BI is associated with enhanced avoidance learning in both humans and animal models. Third, we will review evidence that BI is also associated with enhanced eyeblink conditioning in both humans and animal models. Overall, data from both humans and animals suggest that these personality traits promote enhanced avoidance and associative learning, as well as slowing of extinction in some training protocols, which all support the learning diathesis model. These findings of enhanced learning in vulnerable individuals can be used to develop objective behavioral measures to pre-identify individuals who are more at risk for development of PTSD following traumatic events, allowing for early (possibly preventative) intervention, as well as suggesting possible therapies for PTSD targeted on remediating avoidance or associative learning. Future work should explore the neural substrates of enhanced avoidance and associative learning for behaviorally inhibited individuals in both the animal model and human participants.
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Affiliation(s)
- Michael Todd Allen
- School of Psychological Sciences, University of Northern Colorado, Greeley, CO, United States
- Rutgers Biomedical Health Sciences, Stress and Motivated Behavior Institute, Rutgers University, Newark, NJ, United States
- Central New York Research Corporation, Syracuse, NY, United States
| | - Catherine E. Myers
- Department of Veterans Affairs, VA New Jersey Health Care System, East Orange, NJ, United States
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University-New Jersey Medical School, Newark, NJ, United States
| | - Kevin D. Beck
- Department of Veterans Affairs, VA New Jersey Health Care System, East Orange, NJ, United States
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University-New Jersey Medical School, Newark, NJ, United States
| | - Kevin C. H. Pang
- Department of Veterans Affairs, VA New Jersey Health Care System, East Orange, NJ, United States
- Department of Pharmacology, Physiology and Neuroscience, Rutgers University-New Jersey Medical School, Newark, NJ, United States
| | - Richard J. Servatius
- Rutgers Biomedical Health Sciences, Stress and Motivated Behavior Institute, Rutgers University, Newark, NJ, United States
- Central New York Research Corporation, Syracuse, NY, United States
- Department of Veterans Affairs, Syracuse Veterans Affairs Medical Center, Syracuse, NY, United States
- Department of Psychiatry, State University of New York Upstate Medical University, Syracuse, NY, United States
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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.
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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
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8
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Allen MT, Handy JD, Blankenship MR, Servatius RJ. The distressed (Type D) personality factor of social inhibition, but not negative affectivity, enhances eyeblink conditioning. Behav Brain Res 2018; 345:93-103. [PMID: 29486267 DOI: 10.1016/j.bbr.2018.02.035] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/23/2018] [Accepted: 02/23/2018] [Indexed: 11/19/2022]
Abstract
Recent work has focused on a learning diathesis model in which specific personality factors such as behavioral inhibition (BI) may influence associative learning and in turn increase risk for the development of anxiety disorders. We have found in a series of studies that individuals self-reporting high levels of BI exhibit enhanced acquisition of conditioned eyeblinks. In the study reported here, hypotheses were extended to include distressed (Type D) personality which has been found to be related to BI. Type D personality is measured with the DS-14 scale which includes two subscales measuring negative affectivity (NA) and social inhibition (SI). We hypothesized that SI, which is similar to BI, would result in enhanced acquisition while the effect of NA is unclear. Eighty nine participants completed personality inventories including the Adult Measure of Behavioral Inhibition (AMBI) and DS-14. All participants received 60 acquisition trials with a 500 ms, 1000 Hz, tone CS and a co-terminating 50 ms, 5 psi corneal airpuff US. Participants received either 100% CS-US paired trials or a schedule of partial reinforcement where 50% US alone trials were intermixed into CS-US training. Acquisition of CRs did not differ between the two training protocols. Whereas BI was significantly related to Type D, SI, and NA, only BI and SI individuals exhibited enhanced acquisition of conditioned eyeblinks as compared to non-inhibited individuals. Personality factors now including social inhibition can be used to identify individuals who express enhanced associative learning which lends further support to a learning diathesis model of anxiety disorders.
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Affiliation(s)
- M T Allen
- School of Psychological Sciences, University of Northern Colorado, Greeley, CO, United States; Rutgers Biomedical Health Sciences, Stress and Motivated Behavior Institute, Rutgers University, Newark, NJ, United States; Central New York Research Corporation, Syracuse, NY, United States.
| | - J D Handy
- Central New York Research Corporation, Syracuse, NY, United States; Department of Veterans Affairs, Syracuse Veterans Affairs Medical Center, Syracuse NY, United States
| | - M R Blankenship
- Department of Psychology, Western Illinois University, Macomb, IL, United States
| | - R J Servatius
- Rutgers Biomedical Health Sciences, Stress and Motivated Behavior Institute, Rutgers University, Newark, NJ, United States; Department of Veterans Affairs, Syracuse Veterans Affairs Medical Center, Syracuse NY, United States; Department of Psychiatry, State University of New York Upstate Medical University, Syracuse, NY, United States
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9
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Allen M, Myers C, Servatius R. Uncertainty of trial timing enhances acquisition of conditioned eyeblinks in anxiety vulnerable individuals. Behav Brain Res 2016; 304:86-91. [DOI: 10.1016/j.bbr.2016.02.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 01/18/2016] [Accepted: 02/06/2016] [Indexed: 11/30/2022]
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10
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Servatius RJ. Editorial: Avoidance: From Basic Science to Psychopathology. Front Behav Neurosci 2016; 10:15. [PMID: 26903831 PMCID: PMC4751251 DOI: 10.3389/fnbeh.2016.00015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 01/28/2016] [Indexed: 11/16/2022] Open
Affiliation(s)
- Richard J Servatius
- Neuroscience, Syracuse DVA Medical Center, Stress and Motivated Behavior Institute, Rutgers Biomedical Health Sciences Newark, NJ, USA
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11
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Servatius RJ, Avcu P, Ko N, Jiao X, Beck KD, Minor TR, Pang KCH. Avoidance expression in rats as a function of signal-shock interval: strain and sex differences. Front Behav Neurosci 2015. [PMID: 26217200 PMCID: PMC4491620 DOI: 10.3389/fnbeh.2015.00168] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Inbred Wistar Kyoto (WKY) rats express inhibited temperament, increased sensitivity to stress, and exaggerated expressions of avoidance. A long-standing observation for lever press escape/avoidance learning in rats is the duration of the warning signal (WS) determines whether avoidance is expressed over escape. Outbred female Sprague-Dawley (SD) rats trained with a 10-s WS efficiently escaped, but failed to exhibit avoidance; avoidance was exhibited to a high degree with WSs longer than 20-s. We examined this longstanding WS duration function and extended it to male SD and male and female WKY rats. A cross-over design with two WS durations (10 or 60 s) was employed. Rats were trained (20 trials/session) in four phases: acquisition (10 sessions), extinction (10 sessions), re-acquisition (8 sessions) and re-extinction (8 sessions). Consistent with the literature, female and male SD rats failed to express avoidance to an appreciable degree with a 10-s WS. When these rats were switched to a 60-s WS, performance levels in the initial session of training resembled the peak performance of rats trained with a 60-s WS. Therefore, the avoidance relationship was acquired, but not expressed at 10-s WS. Further, poor avoidance at 10-s does not adversely affect expression at 60-s. Failure to express avoidance with a 10-s WS likely reflects contrasting reinforcement value of avoidance, not a reduction in the amount of time available to respond or competing responses. In contrast, WKY rats exhibited robust avoidance with a 10-s WS, which was most apparent in female WKY rats. Exaggerated expression of avoidances by WKY rats, especially female rats, further confirms this inbred strain as a model of anxiety vulnerability.
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Affiliation(s)
- Richard J Servatius
- Syracuse Veterans Affairs Medical Center, Stress and Motivated Behavior Institute Syracuse, NY, USA ; Department of Neuroscience, Stress and Motivated Behavior Institute, Rutgers Biomedical Health Sciences Newark, NJ, USA ; Rutgers Biomedical Health Sciences, Graduate School of Biomedical Sciences Newark, NJ, USA
| | - Pelin Avcu
- Syracuse Veterans Affairs Medical Center, Stress and Motivated Behavior Institute Syracuse, NY, USA ; Rutgers Biomedical Health Sciences, Graduate School of Biomedical Sciences Newark, NJ, USA
| | - Nora Ko
- Syracuse Veterans Affairs Medical Center, Stress and Motivated Behavior Institute Syracuse, NY, USA ; Rutgers Biomedical Health Sciences, Graduate School of Biomedical Sciences Newark, NJ, USA
| | - Xilu Jiao
- New Jersey Health Care System East Orange, NJ, USA
| | - Kevin D Beck
- Department of Neuroscience, Stress and Motivated Behavior Institute, Rutgers Biomedical Health Sciences Newark, NJ, USA ; Rutgers Biomedical Health Sciences, Graduate School of Biomedical Sciences Newark, NJ, USA ; New Jersey Health Care System East Orange, NJ, USA
| | - Thomas R Minor
- Psychology, University of California at Los Angeles Los Angeles, CA, USA
| | - Kevin C H Pang
- Department of Neuroscience, Stress and Motivated Behavior Institute, Rutgers Biomedical Health Sciences Newark, NJ, USA ; Rutgers Biomedical Health Sciences, Graduate School of Biomedical Sciences Newark, NJ, USA ; New Jersey Health Care System East Orange, NJ, USA
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12
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Janke KL, Cominski TP, Kuzhikandathil EV, Servatius RJ, Pang KCH. Investigating the Role of Hippocampal BDNF in Anxiety Vulnerability Using Classical Eyeblink Conditioning. Front Psychiatry 2015; 6:106. [PMID: 26257661 PMCID: PMC4513557 DOI: 10.3389/fpsyt.2015.00106] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 07/10/2015] [Indexed: 12/27/2022] Open
Abstract
Dysregulation of brain-derived neurotrophic factor (BDNF), behavioral inhibition temperament (BI), and small hippocampal volume have been linked to anxiety disorders. Individuals with BI show facilitated acquisition of the classically conditioned eyeblink response (CCER) as compared to non-BI individuals, and a similar pattern is seen in an animal model of BI, the Wistar-Kyoto (WKY) rat. The present study examined the role of hippocampal BDNF in the facilitated delay CCER of WKY rats. Consistent with earlier work, acquisition was facilitated in WKY rats compared to the Sprague Dawley (SD) rats. Facilitated acquisition was associated with increased BDNF, TrkB, and Arc mRNA in the dentate gyrus of SD rats, but learning-induced increases in BDNF and Arc mRNA were significantly smaller in WKY rats. To determine whether reduced hippocampal BDNF in WKY rats was a contributing factor for their facilitated CCER, BDNF or saline infusions were given bilaterally into the dentate gyrus region 1 h prior to training. BDNF infusion did not alter the acquisition of SD rats, but significantly dampened the acquisition of CCER in the WKY rats, such that acquisition was similar to SD rats. Together, these results suggest that inherent differences in the BDNF system play a critical role in the facilitated associative learning exhibited by WKY rats, and potentially individuals with BI. Facilitated associative learning may represent a vulnerability factor in the development of anxiety disorders.
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Affiliation(s)
- Kellie L Janke
- Research Service, Neurobehavioral Research Laboratory, VA New Jersey Heath Care System , East Orange, NJ , USA ; Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences , Newark, NJ , USA
| | - Tara P Cominski
- Research Service, Neurobehavioral Research Laboratory, VA New Jersey Heath Care System , East Orange, NJ , USA ; Veterans Biomedical Research Institute , East Orange, NJ , USA
| | - Eldo V Kuzhikandathil
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences , Newark, NJ , USA ; Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers Biomedical and Health Sciences , Newark, NJ , USA
| | - Richard J Servatius
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers Biomedical and Health Sciences , Newark, NJ , USA ; Syracuse VA Medical Center , Syracuse, NY , USA
| | - Kevin C H Pang
- Research Service, Neurobehavioral Research Laboratory, VA New Jersey Heath Care System , East Orange, NJ , USA ; Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers Biomedical and Health Sciences , Newark, NJ , USA
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Avcu P, Jiao X, Myers CE, Beck KD, Pang KCH, Servatius RJ. Avoidance as expectancy in rats: sex and strain differences in acquisition. Front Behav Neurosci 2014; 8:334. [PMID: 25339874 PMCID: PMC4186307 DOI: 10.3389/fnbeh.2014.00334] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/05/2014] [Indexed: 11/28/2022] Open
Abstract
Avoidance is a core feature of anxiety disorders and factors which increase avoidance expression or its resistance represent a source of vulnerability for anxiety disorders. Outbred female Sprague Dawley (SD) rats and inbred male and female Wistar-Kyoto (WKY) rats expressing behaviorally inhibited (BI) temperament learn avoidance faster than male SD rats. The training protocol used in these studies had a longstanding interpretive flaw: a lever-press had two outcomes, termination of the warning signal (WS) and prevention of foot shock. To disambiguate between these two explanations, we conducted an experiment in which: (a) a lever-press terminated the WS and prevented shock, and (b) a lever-press only prevented shock, but did not influence the duration of the WS. Thus, a 2 × 2 × 2 (Strain × Sex × Training) design was employed to assess the degree to which the response contingency of the WS termination influenced acquisition. Male and female SD and WKY rats were matched on acoustic startle reactivity within strain and sex and randomly assigned to the training procedures. In addition, we assessed whether the degree of avoidance acquisition affected estrus cycling in female rats. Consistent with earlier work, avoidance performance of female rats was generally superior to males and WKY rats were superior to SD rats. Moreover, female SD and male WKY rats were roughly equivalent. Female sex and BI temperament were confirmed as vulnerability factors in faster acquisition of avoidance behavior. Avoidance acquisition disrupted estrus cycling with female WKY rats recovering faster than female SD rats. Although termination of the WS appears to be reinforcing, male and female WKY rats still achieved a high degree (greater than 80% asymptotic performance) of avoidance in the absence of the WS termination contingency. Such disambiguation will facilitate determination of the neurobiological basis for avoidance learning and its extinction.
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Affiliation(s)
- Pelin Avcu
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA
| | - Xilu Jiao
- Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA
| | - Catherine E Myers
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Neurobehavioral Research Lab, Department of Veteran Affairs Medical Center - New Jersey Health Care System East Orange, NJ, USA
| | - Kevin D Beck
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Neurobehavioral Research Lab, Department of Veteran Affairs Medical Center - New Jersey Health Care System East Orange, NJ, USA
| | - Kevin C H Pang
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Neurobehavioral Research Lab, Department of Veteran Affairs Medical Center - New Jersey Health Care System East Orange, NJ, USA
| | - Richard J Servatius
- Graduate School of Biomedical Sciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Stress and Motivated Behavior Institute, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers Biomedical and Health Sciences Newark, NJ, USA ; Neurobehavioral Research Lab, Department of Veteran Affairs Medical Center - New Jersey Health Care System East Orange, NJ, USA
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14
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Erratum to “Behaviorally inhibited individuals demonstrate significantly enhanced conditioned response acquisition under non-optimal learning conditions” [Behav. Brain Res. 261C (2014) 49-55]. Behav Brain Res 2014. [DOI: 10.1016/j.bbr.2014.01.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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15
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Catuzzi JE, Beck KD. Anxiety vulnerability in women: a two-hit hypothesis. Exp Neurol 2014; 259:75-80. [PMID: 24518489 DOI: 10.1016/j.expneurol.2014.01.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/24/2014] [Accepted: 01/30/2014] [Indexed: 01/04/2023]
Abstract
Females are twice as likely to develop an anxiety disorder compared to males, and thus, are believed to possess an innate vulnerability that increases their susceptibility to develop an anxiety disorder. However, studies using aversive learning paradigms to model anxiety disorders in humans and animals have revealed contradictory results. While females exhibit the ability to rapidly acquire stimulus-response associations, which may result from a greater attentional bias towards threat, females are also capable to readily extinguish these associations. Thus, there is little evidence to suggest that the female sex represents a vulnerability factor of anxiety, per se. However, if females are to possess a second vulnerability factor that increases the inflexibility of stimulus-response associations, then an anxiety disorder may be more likely to develop. Behavioral inhibition (BI) is a vulnerability factor associated with the formation of inflexible stimulus-response associations. In this "two hit" model of anxiety vulnerability, females possessing a BI temperament will rapidly acquire stimulus-response associations that are resistant to extinction, resulting in the development of an anxiety disorder. In this review we explore evidence for a "two-hit" hypothesis underlying anxiety vulnerability in females. We explore the literature for evidence of a sex difference in attentional bias towards threat that may lead to the facilitated acquisition of stimulus-response associations in females. We also provide evidence that BI is associated with inflexible stimulus-response association formation. We conclude with data generated from our laboratory that highlights the additive effect of the female sex and behavioral inhibition vulnerabilities using a model behavior for anxiety disorder-susceptibility, active avoidance.
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Affiliation(s)
- Jennifer E Catuzzi
- Neurobehavioral Research Laboratory, VA New Jersey Heath Care System, East Orange, NJ 07018, USA; Rutgers-Graduate School of Biomedical and Health Science, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA
| | - Kevin D Beck
- Neurobehavioral Research Laboratory, VA New Jersey Heath Care System, East Orange, NJ 07018, USA; Rutgers-Graduate School of Biomedical and Health Science, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA; Stress and Motivated Behavior Institute (SMBI), Department of Neurology and Neurosciences, Rutgers-New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ 07103, USA.
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16
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Holloway JL, Allen MT, Myers CE, Servatius RJ. Behaviorally inhibited individuals demonstrate significantly enhanced conditioned response acquisition under non-optimal learning conditions. Behav Brain Res 2013; 261:49-55. [PMID: 24275381 DOI: 10.1016/j.bbr.2013.10.041] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2013] [Revised: 10/17/2013] [Accepted: 10/24/2013] [Indexed: 11/17/2022]
Abstract
Behavioral inhibition (BI) is an anxiety vulnerability factor associated with hypervigilance to novel stimuli, threat, and ambiguous cues. The progression from anxiety risk to a clinical disorder is unknown, although the acquisition of defensive learning and avoidance may be a critical feature. As the expression of avoidance is also central to anxiety development, the present study examined avoidance acquisition as a function of inhibited temperament using classical eyeblink conditioning. Individuals were classified as behaviorally inhibited (BI) or non-inhibited (NI) based on combined scores from the Adult and Retrospective Measures of Behavioural Inhibition (AMBI and RMBI, respectively). Acquisition was assessed using delay, omission, or yoked conditioning schedules of reinforcement. Omission training was identical to delay, except that the emission of an eyeblink conditioned response (CR) resulted in omission of the unconditioned airpuff stimulus (US) on that trial. Each subject in the yoked group was matched on total BI score to a subject in the omission group, and received the same schedule of CS and US delivery, resulting in a partial reinforcement training schedule. Delay conditioning elicited significantly more CRs compared to the omission and yoked contingencies, the latter two of which did not differ from each other. Thus, acquisition of an avoidance response was not apparent. BI individuals demonstrated enhanced acquisition overall, while partial reinforcement training significantly distinguished between BI and NI groups. Enhanced learning in BI may be a function of an increased defensive learning capacity, or sensitivity to uncertainty. Further work examining the influence of BI on learning acquisition is important for understanding individual differences in disorder etiology in anxiety vulnerable cohorts.
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Affiliation(s)
- J L Holloway
- UMDNJ-GSBS, Newark, NJ, USA; Stress and Motivated Behavior Institute, NJMS-UMDNJ, Newark, NJ, USA
| | - M T Allen
- Stress and Motivated Behavior Institute, NJMS-UMDNJ, Newark, NJ, USA; University of Northern Colorado, Greeley, CO, USA
| | - C E Myers
- Stress and Motivated Behavior Institute, NJMS-UMDNJ, Newark, NJ, USA; Neurobehavioral Res. Lab. (129), DVA Med. Center, NJHCS, East Orange, NJ, USA
| | - R J Servatius
- UMDNJ-GSBS, Newark, NJ, USA; Stress and Motivated Behavior Institute, NJMS-UMDNJ, Newark, NJ, USA; Neurobehavioral Res. Lab. (129), DVA Med. Center, NJHCS, East Orange, NJ, USA.
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17
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Perrotti LI, Dennis TS, Jiao X, Servatius RJ, Pang KCH, Beck KD. Activation of extracellular signal-regulated kinase (ERK) and ΔFosB in emotion-associated neural circuitry after asymptotic levels of active avoidance behavior are attained. Brain Res Bull 2013; 98:102-10. [PMID: 23932962 DOI: 10.1016/j.brainresbull.2013.07.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 06/20/2013] [Accepted: 07/09/2013] [Indexed: 12/30/2022]
Abstract
Avoidance susceptibility may constitute a vulnerability to develop anxiety disorders, and Wistar-Kyoto (WKY) rats exhibit unique features in their acquisition of avoidance behavior that appear to promote susceptibility to this form of learning, namely the absence of the commonly observed "warm-up" effect. The present study sought to determine if strain differences in acquired avoidance behavior, between WKY and Sprague Dawley rats, could be attributed to differences in dopamine-related plasticity, represented by extracellular signal-regulated kinase (ERK) activity, and prolonged neuronal activation, represented by ΔFosB accumulation, in three key areas of the brain: the medial prefrontal cortex (mPFC), dorsal striatum (DS), and basolateral amygdala (BLA). Consistent with earlier work, WKY rats exhibited a higher level of asymptotic performance of avoidance behavior, which included an absence of warm-up in the first few trials of later training sessions, and they exhibited more non-reinforced anticipatory responses in the single minute prior to the initiation of the first warning signal presentation of each training session. In the brain, phosyphorylated ERK2 (pERK2) activation was higher in avoidance trained rats in both the mPFC and DS, although the difference in DS was mostly observed in WKY rats. Avoidance-training was associated with higher levels of ΔFosB expression in the mPFC of SD rats, but not WKY rats. The strain differences in pERK2 activation in the DS and ΔFosB levels in the mPFC may underlie the strain-specific differences observed in warm-up, the emission of non-reinforced anticipatory responses, and general differences in asymptotic performance of active avoidance behavior. The mPFC and DS require further study as potential neural targets for understanding avoidance susceptibility and, as a result, anxiety vulnerability.
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Affiliation(s)
- Linda I Perrotti
- Department of Psychology, The University of Texas at Arlington, Arlington, TX 76019, USA.
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18
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Caulfield MD, McAuley JD, Servatius RJ. Facilitated acquisition of eyeblink conditioning in those vulnerable to anxiety disorders. Front Hum Neurosci 2013; 7:348. [PMID: 23847516 PMCID: PMC3701872 DOI: 10.3389/fnhum.2013.00348] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 06/17/2013] [Indexed: 12/18/2022] Open
Abstract
Behavioral inhibition (BI) increases vulnerability to develop anxiety disorders and is typified by avoidance and withdrawal from novel objects, people, and situations. The present study considered the relationship between BI and temperamental risk factors, such as trait anxiety and acquisition rate of a classically conditioned eyeblink response. One-hundred seventy-four healthy undergraduate students (mean age 20.3 years, 71.8% female) were given the State-Trait Anxiety Inventory and a battery of self-report measures of BI consisting of the Adult and Retrospective Measures of Behavioral Inhibition (AMBI/RMBI) and the Concurrent and Retrospective Self Report of Inhibition (CSRI/RSRI). Participants then underwent standard delay classical eyeblink conditioning consisting of 45 trials with a 500-ms CS overlapping and co-terminating with a 10-ms airpuff US. Individuals with higher scores on the AMBI and Trait Anxiety Inventory, but not the other measures, showed faster acquisition of a conditioned eyeblink response than individuals with lower scores. Results support a relationship between facilitated acquisition of inter-stimulus relationships and risk for anxiety, and suggest that some measures assessing anxiety vulnerability better capture this relationship than others.
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Affiliation(s)
- Meghan D Caulfield
- Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey Newark, NJ, USA ; New Jersey Medical School, Stress and Motivated Behavior Institute, University of Medicine and Dentistry of New Jersey Newark, NJ, USA
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19
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Sheynin J, Shikari S, Gluck MA, Moustafa AA, Servatius RJ, Myers CE. Enhanced avoidance learning in behaviorally inhibited young men and women. Stress 2013; 16:289-99. [PMID: 23101990 PMCID: PMC3767128 DOI: 10.3109/10253890.2012.744391] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Behavioral inhibition (BI) is a temperamental tendency to avoid or withdraw from novel social and nonsocial situations, and has been shown to predispose individuals to anxiety disorders. However, adequate means to assess individual differences in avoidance learning in humans are presently limited. Here, we tested whether individuals with high self-reported BI show faster associative learning on a purely cognitive task and whether such inhibited individuals are more prone to avoid aversive outcomes. In Experiment 1, we tested 74 healthy undergraduate students (mean age 19.5 years; 55.4% female) on a computer-based probabilistic classification task, where participants were asked to classify four distinct visual stimuli into two categories. Two stimuli were associated with reward (point gain) and two were associated with punishment (point loss). In Experiment 2, 79 participants from the same population (mean age 19.8 years; 62% female) were tested on a novel modification of the same task, where they also had the option to opt out of responding on each trial, thus avoiding any chance of being punished (or rewarded) on that trial. Results show that inhibited participants demonstrated better associative learning in Experiment 1, while exhibiting a greater tendency to opt out in Experiment 2 (repeated-measures analysis of variance, main effects of BI, both p < 0.05). These results indicate that the facilitated classically conditioned learning previously observed in inhibited individuals can be extended to a cognitive task, and also highlight a specific preference in inhibited individuals for withdrawal ("opting out") as a response strategy, when multiple strategies are available to avoid punishment.
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Affiliation(s)
- Jony Sheynin
- Joint Biomedical Engineering Program, New Jersey Institute of Technology and Graduate School of Biomedical Sciences, University of Medicine and Dentistry of New Jersey, Newark, NJ 17018, USA.
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20
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Fuzik J, Gellért L, Oláh G, Herédi J, Kocsis K, Knapp L, Nagy D, Kincses ZT, Kis Z, Farkas T, Toldi J. Fundamental interstrain differences in cortical activity between Wistar and Sprague-Dawley rats during global ischemia. Neuroscience 2012; 228:371-81. [PMID: 23103797 DOI: 10.1016/j.neuroscience.2012.10.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 10/18/2012] [Accepted: 10/19/2012] [Indexed: 10/27/2022]
Abstract
Four-vessel occlusion (4VO), a frequently used model of global cerebral ischemia in rats, results in a dysfunction in wide brain areas, including the cerebral cortex and hippocampus. However, there are pronounced differences in response to global ischemia between the laboratory rat strains used in these studies. In the present work, the immediate acute effects of 4VO-induced global ischemia on the spontaneous electrocorticogram (ECoG) signals were analyzed in Wistar and Sprague-Dawley rats. The ECoG was isoelectric during the 10 min of global cerebral ischemia in Wistar rats and the first burst (FB) was seen 10-13 min after the start of reperfusion. In Sprague-Dawley rats, the FB was detected immediately after the start of 4VO or a few seconds later. The burst suppression ratio (BSR) in Wistar rats decreased to 45% in 5 min after FB, and after 25 min it was approximately 40%. In Sprague-Dawley rats, the BSR was 55% immediately after the FB and it decreased steeply to reach 0% by 10 min. There was also a significant difference between the two strains in the frequency composition of the ECoG pattern. The power spectral densities of the two strains differed virtually throughout the post-ischemic state. The histological results (Evans Blue, Cresyl Violet and Fluoro Jade C stainings) supplemented the electrophysiological data: the neuronal damage in the CA1 pyramids in Wistar rats was severe, whereas in the Sprague-Dawley animals it was only partial. These observations clearly demonstrate that the use of different rat strains (e.g. Wistar vs. Sprague-Dawley) can be a source of considerable variability in the results of acute experiments on global ischemia and it is important that the laboratory rats used in such experiments should be carefully chosen.
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Affiliation(s)
- J Fuzik
- University of Szeged, Department of Physiology, Anatomy and Neuroscience, Közép fasor 52, H-6726 Szeged, Hungary
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21
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McBride SD, Mills DS. Psychological factors affecting equine performance. BMC Vet Res 2012; 8:180. [PMID: 23016987 PMCID: PMC3514365 DOI: 10.1186/1746-6148-8-180] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Accepted: 08/17/2012] [Indexed: 12/03/2022] Open
Abstract
For optimal individual performance within any equestrian discipline horses must be in peak physical condition and have the correct psychological state. This review discusses the psychological factors that affect the performance of the horse and, in turn, identifies areas within the competition horse industry where current behavioral research and established behavioral modification techniques could be applied to further enhance the performance of animals. In particular, the role of affective processes underpinning temperament, mood and emotional reaction in determining discipline-specific performance is discussed. A comparison is then made between the training and the competition environment and the review completes with a discussion on how behavioral modification techniques and general husbandry can be used advantageously from a performance perspective.
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Beck KD, Jiao X, Ricart TM, Myers CE, Minor TR, Pang KCH, Servatius RJ. Vulnerability factors in anxiety: Strain and sex differences in the use of signals associated with non-threat during the acquisition and extinction of active-avoidance behavior. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:1659-70. [PMID: 21601608 DOI: 10.1016/j.pnpbp.2011.05.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 04/19/2011] [Accepted: 05/06/2011] [Indexed: 10/18/2022]
Abstract
Rats that exhibit a behaviorally inhibited temperament acquire active-avoidance behaviors quicker, and extinguish them slower, than normal outbred rats. Here we explored the contribution of stimuli that signal periods of non-threat (i.e. safety signals) in the process of acquiring active-avoidance behavior. Utilizing a discrete lever-press escape-avoidance protocol, outbred Sprague-Dawley (SD) rats and inbred, behaviorally inhibited, Wistar-Kyoto (WKY) rats were tested under conditions where a flashing light was either presented or not during periods of non-threat (the inter-trial interval, ITI). For males, we found the absence of the ITI-signal slowed the acquisition of avoidance behavior selectively in WKY rats. However, extinction of the avoidance behavior was not influenced by training with or without the ITI-signal; WKY males extinguished slower than SD males. For females, the presence of the ITI-signal did not affect acquisition in either strain. However, after training with the ITI-signal, females of both strains extinguished quicker in its absence than in its presence. In order to determine if facilitated acquisition of avoidance learning in male WKY rats was due to a paradigm-independent influence of the visual stimulus used as ITI-signal upon associative learning, we conducted eyeblink conditioning in the presence or absence of a similar visual stimulus. No differences in acquisition, as a function of this visual stimulus, were observed within the male WKY rats, but, as was observed in avoidance learning, male WKY rats extinguished slower than male SD rats. Thus, avoidance susceptibility for male WKY rats may be tied both to the presence of non-threat signals as well as a resistance to extinguish Pavlovian-conditioned associations. Female susceptibility to resist extinguishing avoidant behavior is discussed with respect to the possible role of stimuli serving as occasion setters for threat contexts.
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Affiliation(s)
- Kevin D Beck
- Neurobehavioral Research Laboratory, Department of Veterans Affairs New Jersey Health Care System, East Orange, NJ 07018, United States.
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