Department of Psychological Sciences, Purdue University
Purdue Institute for Integrative Neuroscience
making memories since 2014
In combination with this behavioral task, we use
in vivo single unit electrophysiology, pharmacology and pharmacogenetics to track biological changes in the brain as the animal is learning about environmental cues signifying safety, fear and reward.
single unit recording from the basal amygdala (BA)
We developed a novel behavioral task in order to assess the flexibility and precision of fear and reward-seeking behaviors to discriminative environmental cues.
In this task a Reward Cue is paired with sucrose delivery, a Fear Cue is paired with a mild footshock and a compound Fear Cue+Safety Cue is paired with no footshock.
The rats show increased reward seeking during the Reward Cue, increased fear behavior during the Fear Cue, and suppressed fear behavior during the compound Fear Cue+Safety Cue.
In the corticolimbic circuit we have demonstrated:
1.the presence of neurons in the basal amygdala that respond selectively to environmental cues explicitly paired with safety and not to fear or reward cues (Sangha et al, 2013 J Neurosci), a 'safety-specific' microcircuit.
2. a subpopulation of BA neurons showing the same neuronal response to safety and reward-associated cues but not responsive to fear cues (Sangha et al, 2013 J Neurosci), a 'safety+reward' microcircuit. This supports the hypothesis that safety cues engage neuronal circuits encoding reward.
3. dissociable roles of the prelimbic (PL) and infralimbic (IL) regions of the prefrontal cortex: PL is necessary for discriminatory reward seeking whereas the IL is required to discriminate between the safety and fear cues (Sangha et al, 2014 Neuropsychopharm).
4. safety cue responsive BA neurons switch to responding to the fear cue after fear extinction when fear behavior is reduced (Sangha, 2015 Front Beh Neuro)
5. altering D1 receptor activity in the BLA impairs fear suppression during a safety cue (Ng et al, 2018 Neurobiol Learn Mem)