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Wright KM, Cieslewski S, Chu A, McDannald MA. Optogenetic inhibition of the caudal substantia nigra inflates behavioral responding to uncertain threat and safety. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.18.529041. [PMID: 36824795 PMCID: PMC9949108 DOI: 10.1101/2023.02.18.529041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
Defensive responding is adaptive when it approximates current threat, but maladaptive when it exceeds current threat. Here we asked if the substantia nigra, a region consistently implicated in reward, is necessary to show appropriate levels of defensive responding in Pavlovian fear discrimination. Rats received bilateral transduction of the caudal substantia nigra with halorhodopsin or a control fluorophore, and bilateral ferrule implants. Rats then behaviorally discriminated cues predicting unique foot shock probabilities (danger, p =1; uncertainty, p =0.25; and safety, p =0). Green-light illumination (532 nm) during cue presentation inflated defensive responding of halorhodopsin rats - measured by suppression of reward seeking - to uncertainty and safety beyond control levels. Green-light illumination outside of cue presentation had no impact on halorhodopsin or control rat responding. The results reveal caudal substantia nigra cue activity is necessary to inhibit defensive responding to non-threatening and uncertain threat cues.
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Affiliation(s)
| | | | - Amanda Chu
- Boston College, Department of Psychology & Neuroscience
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2
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Bauer EP. Sex differences in fear responses: Neural circuits. Neuropharmacology 2023; 222:109298. [PMID: 36328063 PMCID: PMC11267399 DOI: 10.1016/j.neuropharm.2022.109298] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/26/2022] [Accepted: 10/19/2022] [Indexed: 11/06/2022]
Abstract
Women have increased vulnerability to PTSD and anxiety disorders compared to men. Understanding the neurobiological underpinnings of these disorders is critical for identifying risk factors and developing appropriate sex-specific interventions. Despite the clear clinical relevance of an examination of sex differences in fear responses, the vast majority of pre-clinical research on fear learning and memory formation has exclusively used male animals. This review highlights sex differences in context and cued fear conditioning, fear extinction and fear generalization with a focus on the neural circuits underlying these behaviors in rodents. There are mixed reports of behavioral sex differences in context and cued fear conditioning paradigms, which can depend upon the behavioral indices of fear. However, there is greater evidence of differential activation of the hippocampus, amygdalar nuclei and the prefrontal cortical regions in male and female rodents during context and cued fear conditioning. The bed nucleus of the stria terminalis (BNST), a sexually dimorphic structure, is of particular interest as it differentially contributes to fear responses in males and females. In addition, while the influence of the estrous cycle on different phases of fear conditioning is delineated, the clearest modulatory effect of estrogen is on fear extinction processes. Examining the variability in neural responses and behavior in both sexes should increase our understanding of how that variability contributes to the neurobiology of affective disorders. This article is part of the Special Issue on 'Fear, anxiety and PTSD'.
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Affiliation(s)
- Elizabeth P Bauer
- Departments of Biology and Neuroscience & Behavior, Barnard College of Columbia University, 3009 Broadway, New York, NY, 10027, United States.
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Wehrli JM, Xia Y, Gerster S, Bach DR. Measuring human trace fear conditioning. Psychophysiology 2022; 59:e14119. [PMID: 35675529 PMCID: PMC9787976 DOI: 10.1111/psyp.14119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/17/2022] [Accepted: 05/02/2022] [Indexed: 12/31/2022]
Abstract
Trace fear conditioning is an important research paradigm to model aversive learning in biological or clinical scenarios, where predictors (conditioned stimuli, CS) and aversive outcomes (unconditioned stimuli, US) are separated in time. The optimal measurement of human trace fear conditioning, and in particular of memory retention after consolidation, is currently unclear. We conducted two identical experiments (N1 = 28, N2 = 28) with a 15-s trace interval and a recall test 1 week after acquisition, while recording several psychophysiological observables. In a calibration approach, we explored which learning and memory measures distinguished CS+ and CS- in the first experiment and confirmed the most sensitive measures in the second experiment. We found that in the recall test without reinforcement, only fear-potentiated startle but not skin conductance, pupil size, heart period, or respiration amplitude, differentiated CS+ and CS-. During acquisition without startle probes, skin conductance responses and pupil size responses but not heart period or respiration amplitude differentiated CS+ and CS-. As a side finding, there was no evidence for extinction of fear-potentiated startle over 30 trials without reinforcement. These results may be useful to inform future substantive research using human trace fear conditioning protocols.
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Affiliation(s)
- Jelena M. Wehrli
- Computational Psychiatry Research, Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatric HospitalUniversity of ZurichZurichSwitzerland
| | - Yanfang Xia
- Computational Psychiatry Research, Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatric HospitalUniversity of ZurichZurichSwitzerland
| | - Samuel Gerster
- Computational Psychiatry Research, Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatric HospitalUniversity of ZurichZurichSwitzerland
| | - Dominik R. Bach
- Computational Psychiatry Research, Department of Psychiatry, Psychotherapy, and Psychosomatics, Psychiatric HospitalUniversity of ZurichZurichSwitzerland,Wellcome Centre for Human Neuroimaging & Max Planck UCL Centre for Computational Psychiatry and Ageing ResearchUniversity College LondonLondonUK
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Adkins JM, Halcomb CJ, Rogers D, Jasnow AM. Stress and sex-dependent effects on conditioned inhibition of fear. Learn Mem 2022; 29:246-255. [PMID: 36206391 PMCID: PMC9488025 DOI: 10.1101/lm.053508.121] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 05/10/2022] [Indexed: 10/14/2022]
Abstract
Anxiety and stress-related disorders are highly prevalent and are characterized by excessive fear to threatening and nonthreatening stimuli. Moreover, there is a large sex bias in vulnerability to anxiety and stress-related disorders-women make up a disproportionately larger number of affected individuals compared with men. Growing evidence suggests that an impaired ability to suppress fear in the presence of safety signals may in part contribute to the development and maintenance of many anxiety and stress-related disorders. However, the sex-dependent impact of stress on conditioned inhibition of fear remains unclear. The present study investigated sex differences in the acquisition and recall of conditioned inhibition in male and female mice with a focus on understanding how stress impacts fear suppression. In these experiments, the training context served as the "fear" cue and an explicit tone served as the "safety" cue. Here, we found a possible sex difference in the training requirements for safety learning, although this effect was not consistent across experiments. Reductions in freezing to the safety cue in female mice were also not due to alternative fear behavior expression such as darting. Next, using footshock as a stressor, we found that males were impaired in conditioned inhibition of freezing when the stress was experienced before, but not after, conditioned inhibition training. Females were unaffected by footshock stress when it was administered at either time. Extended conditioned inhibition training in males eliminated the deficit produced by footshock stress. Finally, exposing male and female mice to swim stress impaired safety learning in male mice only. Thus, we found sex × stress interactions in the learning of conditioned inhibition and sex-dependent effects of stress modality. The present study adds to the growing literature on sex differences in safety learning, which will be critical for developing sex-specific therapies for a variety of fear-related disorders that involve excessive fear and/or impaired fear inhibition.
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Affiliation(s)
- Jordan M Adkins
- Department of Psychological Sciences, Brain Health Research Institute, Kent State University, Kent, Ohio 44242, USA
| | - Carly J Halcomb
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina 29209, USA
| | - Danielle Rogers
- Department of Psychological Sciences, Brain Health Research Institute, Kent State University, Kent, Ohio 44242, USA
| | - Aaron M Jasnow
- Department of Pharmacology, Physiology, and Neuroscience, University of South Carolina School of Medicine, Columbia, South Carolina 29209, USA
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Meyer HC, Sangha S, Radley JJ, LaLumiere RT, Baratta MV. Environmental certainty influences the neural systems regulating responses to threat and stress. Neurosci Biobehav Rev 2021; 131:1037-1055. [PMID: 34673111 PMCID: PMC8642312 DOI: 10.1016/j.neubiorev.2021.10.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 09/29/2021] [Accepted: 10/01/2021] [Indexed: 10/20/2022]
Abstract
Flexible calibration of threat responding in accordance with the environment is an adaptive process that allows an animal to avoid harm while also maintaining engagement of other goal-directed actions. This calibration process, referred to as threat response regulation, requires an animal to calculate the probability that a given encounter will result in a threat so they can respond accordingly. Here we review the neural correlates of two highly studied forms of threat response suppression: extinction and safety conditioning. We focus on how relative levels of certainty or uncertainty in the surrounding environment alter the acquisition and application of these processes. We also discuss evidence indicating altered threat response regulation following stress exposure, including enhanced fear conditioning, and disrupted extinction and safety conditioning. To conclude, we discuss research using an animal model of coping that examines the impact of stressor controllability on threat responding, highlighting the potential for previous experiences with control, or other forms of coping, to protect against the effects of future adversity.
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Affiliation(s)
- Heidi C Meyer
- Department of Psychological and Brain Sciences, Boston University, Boston, MA, 02215, USA.
| | - Susan Sangha
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, 47907, USA.
| | - Jason J Radley
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, 52242, USA.
| | - Ryan T LaLumiere
- Department of Psychological and Brain Sciences, University of Iowa, Iowa City, IA, 52242, USA.
| | - Michael V Baratta
- Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, 80301, USA.
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Fendt M, Kreutzmann JC, Jovanovic T. Learning safety to reduce fear: Recent insights and potential implications. Behav Brain Res 2021; 411:113402. [PMID: 34089756 DOI: 10.1016/j.bbr.2021.113402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Markus Fendt
- Otto-von-Guericke University Magdeburg, Institute for Pharmacology and Toxicology, Leipziger Str. 44, D-39120, Magdeburg, Germany.
| | - Judith C Kreutzmann
- Otto-von-Guericke University Magdeburg, Institute for Pharmacology and Toxicology, Leipziger Str. 44, D-39120, Magdeburg, Germany.
| | - Tanja Jovanovic
- Wayne State University, School of Medicine, Psychiatry and Behavioral Neuroscience, 245 Tolan Park Medical Building, 3901 Chrysler Service Drive, Detroit, MI, 48201, USA
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Laing PA, Vervliet B, Fullana MA, Savage HS, Davey CG, Felmingham KL, Harrison BJ. Characterizing human safety learning via Pavlovian conditioned inhibition. Behav Res Ther 2021; 137:103800. [DOI: 10.1016/j.brat.2020.103800] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 12/09/2020] [Accepted: 12/28/2020] [Indexed: 02/08/2023]
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Krueger JN, Sangha S. On the basis of sex: Differences in safety discrimination vs. conditioned inhibition. Behav Brain Res 2020; 400:113024. [PMID: 33290755 DOI: 10.1016/j.bbr.2020.113024] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/19/2020] [Accepted: 11/18/2020] [Indexed: 01/04/2023]
Abstract
Inaccurate discrimination between threat and safety cues is a common symptom of anxiety disorders such as Post-Traumatic Stress Disorder (PTSD). Although females experience higher rates of these disorders than males, the body of literature examining sex differences in safety learning is still growing. Learning to discriminate safety cues from threat cues requires downregulating fear to the safety cue while continuing to express fear to the threat cue. However, successful discrimination between safety and threat cues does not necessarily guarantee that the safety cue can effectively reduce fear to the threat cue when they are presented together. The conditioned inhibitory ability of a safety cue to reduce fear in the presence of both safety and threat is most likely dependent on the ability to discriminate between the two. There are relatively few studies exploring conditioned inhibition as a method of safety learning. Adding to this knowledge gap is the general lack of inclusion of female subjects within these studies. In this review, we provide a qualitative review of our current knowledge of sex differences in safety discrimination versus conditioned inhibition in both humans and rodents. Overall, the literature suggests that while females and males perform similarly in discrimination learning, females show deficits in conditioned inhibition compared to males. Furthermore, while estrogen appears to have a protective effect on safety learning in humans, increased estrogen in female rodents appears to be correlated with impaired safety learning performance.
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Affiliation(s)
- Jamie N Krueger
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, 47907, USA.
| | - Susan Sangha
- Department of Psychological Sciences, Purdue University, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, 47907, USA.
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