Electrical stimulation of medial prefrontal cortex reduces conditioned fear in a temporally specific manner.
The authors recently showed that extinction of auditory fear conditioning leads to potentiation of tone-evoked activity of neurons in the infralimbic (IL) subregion of the medial prefrontal cortex, suggesting that IL inhibits fear after extinction (M. R. Milad, & G. J. Quirk, 2002). In support of this finding, pairing conditioned tones with brief (300-ms) electrical stimulation of IL reduces conditioned freezing. The present study showed that IL stimulation inhibits freezing if given 0.1 s after tone onset (the latency of tone-evoked responses) but has no effect if given either 1 s before or 1 s after tone onset. This suggests that IL gates the response of downstream structures such as the amygdala to fear stimuli.
Milad
M R
MR
Department of Physiology, Ponce School of Medicine, Ponce, PR 00732-7004.
Vidal-Gonzalez
I
I
Quirk
G J
GJ
D000818:Animals; D003213:Conditioning, Psychological; D004558:Electric Stimulation / Q000295:instrumentation; D004567:Electrodes, Implanted; D005108:Extinction, Psychological; D005239:Fear; D011939:Mental Recall; D017397:Prefrontal Cortex / Q000502:physiology*; D051381:Rats; D012055:Reinforcement Schedule; D013997:Time Factors