Differential effects of nicotinic acetylcholine receptor stimulation on negative occasion setting.

We have previously shown that nicotine enhances learning in a negative occasion setting task in which rats are trained to distinguish between two different trial types. During reinforced trials, a target stimulus (a tone) is presented and immediately followed by food reward. On nonreinforced trials, a feature stimulus (a light) is presented prior to the tone and indicates the absence of reward following presentation of the tone.

Contributions of the subregions of the medial prefrontal cortex to negative occasion setting.

The medial prefrontal cortex of rats has a role in many aspects of cognitive function, including forms of inhibitory learning. Recent studies suggest that there is heterogeneity in the contributions of the prelimbic (PL) and infralimbic (IL) regions of the medial prefrontal cortex to response inhibition. The present study tested the effects of separate neurotoxic lesions of the PL or IL on a serial feature negative discrimination task (negative occasion setting).

Changes in neural activity associated with a surprising change in the predictive validity of a conditioned stimulus.

Changes in how well a conditioned stimulus (CS) predicts future events can alter the amount of attention paid to that cue. For example, the unexpected violation of a previously established relationship between a CS and another stimulus can increase attentional processing and subsequent conditioning to that cue [J.M.

Cancer chemotherapy impairs contextual but not cue-specific fear memory.

This study examined the effects of a standard breast cancer chemotherapeutic protocol on learning and memory in rats. Ovariectomized rats were treated once a week for 3 weeks with a combination of cyclophosphamide and doxorubicin prior to training in a classical fear conditioning task. Training took place 1 week after the final treatment.

Nicotine administration enhances conditioned inhibition in rats.

The effect of nicotine on conditioned inhibition was examined using a serial feature negative discrimination task. Nicotine (0.35 mg/kg) or vehicle was administered before each of the 16 training sessions.