Updating temporal expectancy of an aversive event engages striatal plasticity under amygdala control.

Pavlovian aversive conditioning requires learning of the association between a conditioned stimulus (CS) and an unconditioned, aversive stimulus (US) but also involves encoding the time interval between the two stimuli. The neurobiological bases of this time interval learning are unknown. Here, we show that in rats, the dorsal striatum and basal amygdala belong to a common functional network underlying temporal expectancy and learning of a CS-US interval.

Fast, transient cardiac accelerations and decelerations during fear conditioning in rats.

The current study reports on a number of heart rate responses observed in rats subjected to a discriminatory Pavlovian fear conditioning procedure. Rats learned that a series of six auditory pips was followed by a footshock when presented alone, but not when the pip series was preceded by a visual safety signal. Each auditory pip in the series evoked a fast transient (<1s) cardiac deceleration.

Influence of emotional arousal on the N150 of the Auditory Evoked Potential from the rat amygdala.

This study tested whether a general increase in emotional arousal is a sufficient determinant for the evocation of the N150, a negative wave in amygdalar Auditory Evoked Potentials (AEPs). Rats received one of three conditioning protocols: either conditioned stimulus (CS) presentations alone (Control) CS-shock pairings (Paired) or unpaired presentations of the CS and shock (Unpaired). Amygdalar AEPs were recorded in response to the CS.

Effect of appetitive Pavlovian conditioning on the N150 of the amygdalar Auditory Evoked Potential in the rat.

A large, negative wave which reaches its peak amplitude around 150 ms after stimulus onset, can be found in the Auditory Evoked Potential (AEP) recorded from the lateral amygdala in the rat. Previous studies in our laboratory have repeatedly shown that this N150 component increases during various aversive conditioning protocols and that this increase is attributable to both increases in emotional arousal that are inherent to aversive conditioning and to the formation of an association between the conditioned stimulus (CS) and the aversive unconditioned stimulus (US). Currently it is not known whether the N150 is also enhanced in conditioning procedures with positive reinforcement.

N150 in amygdalar ERPs in the rat: is there modulation by anticipatory fear?

The hypothesis was tested whether the amygdalar N150 of rats, a slow, negative component in the event-related potential from the lateral amygdala, is sensitive to a state of anxious anticipation. A conditioning procedure was applied in which a series of six auditory stimuli was followed by a shock when presented alone, but not when the auditory stimuli were preceded by a visual stimulus. Heart rate recordings confirmed that the auditory stimulus train induced a state of increasing anticipatory fear and that this condition was modulated by the visual stimulus.