The ventrolateral periaqueductal gray (vlPAG) is proposed to mediate fear responses to imminent danger. Previously we reported that vlPAG neurons showing short-latency increases in firing to danger cues - the presumed neural substrate for fear output - signal threat probability in male rats (Wright et al., 2019). Here, we scrutinize the activity of cue-inhibited vlPAG neurons that show decreases in firing to danger cues. One cue-inhibited population flipped danger activity from early inhibition to late excitation: a poor neural substrate for fear output, but a better substrate for threat timing. A second population showed differential firing with greatest inhibition to danger, less to uncertainty and no inhibition to safety. Differential firing by this second population reflected the pattern of fear output, and was observed throughout cue presentation. The results reveal an expected vlPAG signal for fear output in an unexpected, cue-inhibited population.
Data have been deposited at: http://crcns.org/data-sets/bst/pag-1
Ventrolateral periaqueductal gray single-single unit activity during multi-cue fear discrimination in ratsCollaborative Research in Computational Neuroscience, PAG-1.
- Michael A McDannald
- Michael A McDannald
- Kristina M Wright
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols (#2018-002) of Boston College. The protocol was approved by the Institutional Animal Care and Use Committee of Boston College. All surgery was performed under isoflurane anesthesia, and every effort was made to minimize suffering.
- Thorsten Kahnt, Northwestern University Feinberg School of Medicine, United States
© 2019, Wright et al.
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