Ekaterina Likhtik

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In extinction of auditory fear conditioning, rats learn that a tone no longer predicts the occurrence of a footshock. Recent lesion and unit recording studies suggest that the medial prefrontal cortex (mPFC) plays an essential role in the inhibition of conditioned fear following extinction. mPFC has robust projections to the amygdala, a structure that is(More)
Congruent findings from studies of fear learning in animals and humans indicate that research on the circuits mediating fear constitutes our best hope of understanding human anxiety disorders. In mammals, repeated presentations of a conditioned stimulus that was previously paired to a noxious stimulus leads to the gradual disappearance of conditioned fear(More)
Accumulating evidence indicates that phobic and posttraumatic anxiety disorders likely result from a failure to extinguish fear memories. Extinction normally depends on a new learning that competes with the original fear memory and is driven by medial prefrontal cortex (mPFC) projections to the amygdala. Although mPFC stimulation was reported to inhibit the(More)
This study tested whether firing rate and spike shape could be used to distinguish projection cells from interneurons in extracellular recordings of basolateral amygdala (BLA) neurons. To this end, we recorded BLA neurons in isoflurane-anesthetized animals with tungsten microelectrodes. Projection cells were identified by antidromic activation from cortical(More)
Successfully differentiating safety from danger is an essential skill for survival. While decreased activity in the medial prefrontal cortex (mPFC) is associated with fear generalization in animals and humans, the circuit-level mechanisms used by the mPFC to discern safety are not clear. To answer this question, we recorded activity in the mPFC, basolateral(More)
Stimuli that possess inherently rewarding or aversive qualities elicit emotional responses and also induce learning by imparting valence upon neutral sensory cues. Evidence has accumulated implicating the amygdala as a critical structure in mediating these processes. We have developed a genetic strategy to identify the representations of rewarding and(More)
Theta oscillations synchronize the basolateral amygdala (BLA) with the hippocampus (HPC) and medial prefrontal cortex (mPFC) during fear expression. The role of gamma-frequency oscillations in the BLA is less well characterized. We examined gamma- and theta-frequency activity in recordings of neural activity from the BLA-HPC-mPFC circuit during fear(More)
The study of neurobiological mechanisms underlying anxiety disorders has been shaped by learning models that frame anxiety as maladaptive learning. Pavlovian conditioning and extinction are particularly influential in defining learning stages that can account for symptoms of anxiety disorders. Recently, dynamic and task related communication between the(More)
UNLABELLED Negative experiences are quickly learned and long remembered. Key unresolved issues in the field of emotional memory include identifying the loci and dynamics of memory storage and retrieval. The present study examined neural activity in the higher-order auditory cortex Te2 and basolateral amygdala (BLA) and their crosstalk during the recall of(More)
Manipulations that reduce or enhance the activity of basolateral amygdala (BLA) neurons in the minutes to hours after training have been shown to respectively impair or facilitate retention on the inhibitory avoidance task. Although this suggests that BLA activity is altered after emotional arousal, such changes have not been directly demonstrated. To test(More)