Contributions of the Nucleus Accumbens Shell in Mediating the Enhancement in Memory Following Noradrenergic Activation of Either the Amygdala or Hippocampus.

The nucleus accumbens shell is a site of converging inputs during memory processing for emotional events. The accumbens receives input from the nucleus of the solitary tract (NTS) regarding changes in peripheral autonomic functioning following emotional arousal. The shell also receives input from the amygdala and hippocampus regarding affective and contextual attributes of new learning experiences.

Prelimbic and infralimbic cortical regions differentially encode cocaine-associated stimuli and cocaine-seeking before and following abstinence.

Cocaine stimuli often trigger relapse of drug-taking, even following periods of prolonged abstinence. Here, electrophysiological recordings were made in rats (n = 29) to determine how neurons in the prelimbic (PrL) or infralimbic (IL) regions of the medial prefrontal cortex (mPFC) encode cocaine-associated stimuli and cocaine-seeking, and whether this processing is differentially altered after 1 month of cocaine abstinence. After self-administration training, neurons (n = 308) in the mPFC were recorded during a single test session conducted either the next day or 1 month later.

Interactions between brainstem noradrenergic neurons and the nucleus accumbens shell in modulating memory for emotionally arousing events.

The nucleus accumbens shell (NAC) receives axons containing dopamine-β-hydroxylase that originate from brainstem neurons in the nucleus of the solitary tract (NTS). Recent findings show that memory enhancement produced by stimulating NTS neurons after learning may involve interactions with the NAC. However, it is unclear whether these mnemonic effects are mediated by norepinephrine (NE) release from NTS terminals onto NAC neurons.

Functional interactions between the nucleus tractus solitarius (NTS) and nucleus accumbens shell in modulating memory for arousing experiences.

The shell division of the nucleus accumbens receives noradrenergic input from neurons in the nucleus of the solitary tract (NTS) that transmit information regarding fluctuations in peripheral hormonal and autonomic activity. Accumbens shell neurons also receive converging inputs from limbic areas such as the hippocampus and amygdala that process newly acquired information. However, few studies have explored whether peripheral information regarding changes in emotional arousal contributes to memory processing in the accumbens.

Control of appetitive and aversive taste-reactivity responses by an auditory conditioned stimulus in a devaluation task: a FOS and behavioral analysis.

Through associative learning, cues for biologically significant reinforcers such as food may gain access to mental representations of those reinforcers. Here, we used devaluation procedures, behavioral assessment of hedonic taste-reactivity responses, and measurement of immediate-early gene (IEG) expression to show that a cue for food engages behavior and brain activity related to sensory and hedonic processing of that food. Rats first received a tone paired with intraoral infusion of sucrose.

Dissociation of attention in learning and action: effects of lesions of the amygdala central nucleus, medial prefrontal cortex, and posterior parietal cortex.

Many associative learning theories assert that the predictive accuracy of events affects the allocation of attention to them. More reliable predictors of future events are usually more likely to control action based on past learning, but less reliable predictors are often more likely to capture attention when new information is acquired. Previous studies showed that a circuit including the amygdala central nucleus (CEA) and the cholinergic substantia innominata/nucleus basalis magnocellularis (SI/nBM) is important for both sustained attention guiding action in a five-choice serial reaction time (5CSRT) task and for enhanced new learning about less predictive cues in a serial conditioning task.

Amygdala central nucleus function is necessary for learning, but not expression, of conditioned auditory orienting.

In Pavlovian appetitive conditioning, rats often acquire 2 classes of conditioned responses: those whose form is determined by the reinforcer, and those whose form is determined by characteristics of the conditioned stimulus (CS). Consistent with the results of previous lesion studies, reversible inactivation of amygdala central nucleus function during pairings of an auditory CS with food prevented the acquisition of conditioned orienting responses specific to auditory CSs, whereas food-related conditioned behaviors were acquired normally. Neither inactivation nor posttraining neurotoxic lesions of the central nucleus affected the expression of previously acquired conditioned orienting.

Amygdala central nucleus function is necessary for learning but not expression of conditioned visual orienting.

When exposed to pairings of a visual stimulus with food delivery, rats normally acquire both conditioned orienting responses directed toward the visual stimulus and conditioned food-related responses. Consistent with the results of previous lesion studies, reversible inactivation of amygdala central nucleus function before each conditioning session prevented the acquisition of conditioned orienting responses, whereas food-related behaviors were acquired normally. By contrast, neither inactivation nor neurotoxic lesions of central nucleus affected the expression of previously acquired conditioned orienting responses.