scholarly journals Dopamine and fear memory formation in the human amygdala

2021 ◽  
Author(s):  
Andreas Frick ◽  
Johannes Björkstrand ◽  
Mark Lubberink ◽  
Allison Eriksson ◽  
Mats Fredrikson ◽  
...  
Keyword(s):  
Fear Conditioning ◽  
Dopamine Release ◽  
Conditioned Fear ◽  
Fear Memory ◽  
Memory Formation ◽  
Fear Learning ◽  
Causative Role ◽  
Endogenous Dopamine ◽  
Positron Emission ◽  
Endogenous Dopamine Release

AbstractLearning which environmental cues that predict danger is crucial for survival and accomplished through Pavlovian fear conditioning. In humans and rodents alike, fear conditioning is amygdala-dependent and rests on similar neurocircuitry. Rodent studies have implicated a causative role for dopamine in the amygdala during fear memory formation, but the role of dopamine in aversive learning in humans is unclear. Here, we show dopamine release in the amygdala and striatum during fear learning in humans. Using simultaneous positron emission tomography and functional magnetic resonance imaging, we demonstrate that the amount of dopamine release is linked to strength of conditioned fear responses and linearly coupled to learning-induced activity in the amygdala. Thus, like in rodents, formation of amygdala-dependent fear memories in humans seems to be facilitated by endogenous dopamine release, supporting an evolutionary conserved neurochemical mechanism for aversive memory formation.

scholarly journals Dopamine facilitates fear memory formation in the human amygdala

2021 ◽  
Author(s):  
Andreas Frick ◽  
Johannes Björkstrand ◽  
Mark Lubberink ◽  
Allison Eriksson ◽  
Mats Fredrikson ◽  
...  
Keyword(s):  
Fear Conditioning ◽  
Dopamine Release ◽  
Conditioned Fear ◽  
Fear Memory ◽  
Memory Formation ◽  
Fear Learning ◽  
Causative Role ◽  
Endogenous Dopamine ◽  
Positron Emission ◽  
Endogenous Dopamine Release

ABSTRACTLearning which environmental cues that predict danger is crucial for survival and accomplished through Pavlovian fear conditioning. In humans and rodents alike, fear conditioning is amygdala-dependent and rests on similar neurocircuitry. Rodent studies have implicated a causative role for dopamine in the amygdala during fear memory formation, but the role of dopamine in aversive learning in humans is unclear. Here, we show dopamine release in the amygdala and striatum during fear learning in humans. Using simultaneous positron emission tomography and functional magnetic resonance imaging, we demonstrate that the amount of dopamine release is linked to strength of conditioned fear responses and linearly coupled to learning-induced memory trace activity in the amygdala. Thus, like in rodents, formation of amygdala-dependent fear memories in humans seems to be facilitated by endogenous dopamine release, supporting an evolutionary conserved neurochemical mechanism for aversive memory formation.

scholarly journals Cerebellar molecular layer interneurons are dispensable for cued and contextual fear conditioning

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Katy L. H. Marshall-Phelps ◽  
Gernot Riedel ◽  
Peer Wulff ◽  
Marta Woloszynowska-Fraser
Keyword(s):  
Fear Conditioning ◽  
Purkinje Cells ◽  
Cerebellar Cortex ◽  
Conditioned Fear ◽  
Molecular Layer ◽  
Fear Memory ◽  
Memory Formation ◽  
Contextual Fear Conditioning ◽  
Contextual Fear

AbstractPurkinje cells are the only output cell of the cerebellar cortex. Their spatiotemporal activity is controlled by molecular layer interneurons (MLIs) through GABAA receptor-mediated inhibition. Recently, it has been reported that the cerebellar cortex is required for consolidation of conditioned fear responses during fear memory formation. Although the relevance of MLIs during fear memory formation is currently not known, it has been shown that synapses made between MLIs and Purkinje cells exhibit long term plasticity following fear conditioning. The present study examined the role of cerebellar MLIs in the formation of fear memory using a genetically-altered mouse line (PC-∆γ2) in which GABAA receptor-mediated signaling at MLI to Purkinje cell synapses was functionally removed. We found that neither acquisition nor recall of fear memories to tone and context were altered after removal of MLI-mediated inhibition.

scholarly journals Fear conditioning and stimulus generalization in association with age in children and adolescents

2021 ◽  
Author(s):  
Julia Reinhard ◽  
Anna Slyschak ◽  
Miriam A. Schiele ◽  
Marta Andreatta ◽  
Katharina Kneer ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Fear Conditioning ◽  
Repeated Measures ◽  
Conditioned Fear ◽  
Fear Learning ◽  
Stimulus Generalization ◽  
Healthy Children ◽  
Older Individuals ◽  
Age Related ◽  
Current Task

AbstractThe aim of the study was to investigate age-related differences in fear learning and generalization in healthy children and adolescents (n = 133), aged 8–17 years, using an aversive discriminative fear conditioning and generalization paradigm adapted from Lau et al. (2008). In the current task, participants underwent 24 trials of discriminative conditioning of two female faces with neutral facial expressions, with (CS+) or without (CS−) a 95-dB loud female scream, presented simultaneously with a fearful facial expression (US). The discriminative conditioning was followed by 72 generalization trials (12 CS+, 12 GS1, 12 GS2, 12 GS3, 12 GS4, and 12 CS−): four generalization stimuli depicting gradual morphs from CS+ to CS− in 20%-steps were created for the generalization phases. We hypothesized that generalization in children and adolescents is negatively correlated with age. The subjective ratings of valence, arousal, and US expectancy (the probability of an aversive noise following each stimulus), as well as skin conductance responses (SCRs) were measured. Repeated-measures ANOVAs on ratings and SCR amplitudes were calculated with the within-subject factors stimulus type (CS+, CS−, GS1-4) and phase (Pre-Acquisition, Acquisition 1, Acquisition 2, Generalization 1, Generalization 2). To analyze the modulatory role of age, we additionally calculated ANCOVAs considering age as covariate. Results indicated that (1) subjective and physiological responses were generally lower with increasing age irrespective to the stimulus quality, and (2) stimulus discrimination improved with increasing age paralleled by reduced overgeneralization in older individuals. Longitudinal follow-up studies are required to analyze fear generalization with regard to brain maturational aspects and clarify whether overgeneralization of conditioned fear promotes the development of anxiety disorders or vice versa.

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