Valence and salience encoding in the central amygdala.

The central amygdala (CeA) has emerged as an important brain region for regulating both negative (fear and anxiety) and positive (reward) affective behaviors. The CeA has been proposed to encode affective information in the form of valence (whether the stimulus is good or bad) or salience (how significant is the stimulus), but the extent to which these two types of stimulus representation occur in the CeA is not known. Here, we used single cell calcium imaging in mice during appetitive and aversive conditioning and found that majority of CeA neurons (~65%) encode the valence of the unconditioned stimulus (US) with a smaller subset of cells (~15%) encoding the salience of the US.

Periaqueductal gray activates antipredatory neural responses in the amygdala of foraging rats.

Pavlovian fear conditioning research suggests that the interaction between the dorsal periaqueductal gray (dPAG) and basolateral amygdala (BLA) acts as a prediction error mechanism in the formation of associative fear memories. However, their roles in responding to naturalistic predatory threats, characterized by less explicit cues and the absence of reiterative trial-and-error learning events, remain unexplored. In this study, we conducted single-unit recordings in rats during an 'approach food-avoid predator' task, focusing on the responsiveness of dPAG and BLA neurons to a rapidly approaching robot predator.

Valence and Salience Encoding in the Central Amygdala.

The central amygdala (CeA) has emerged as an important brain region for regulating both negative (fear and anxiety) and positive (reward) affective behaviors. The CeA has been proposed to encode affective information in the form of valence (whether the stimulus is good or bad) or salience (how significant is the stimulus), but the extent to which these two types of stimulus representation occur in the CeA is not known. Here, we used single cell calcium imaging in mice during appetitive and aversive conditioning and found that majority of CeA neurons (~65%) encode the valence of the unconditioned stimulus (US) with a smaller subset of cells (~15%) encoding the salience of the US.

Temporal scaling of dopamine neuron firing and dopamine release by distinct ion channels shape behavior.

Dopamine is broadly implicated in reinforcement learning, but how patterns of dopamine activity are generated is poorly resolved. Here, we demonstrate that two ion channels, Kv4.3 and BKCa1.

Differential Encoding of Trace and Delay Fear Memory in the Entorhinal Cortex.

Trace fear conditioning is characterized by a stimulus-free trace interval (TI) between the conditioned stimulus (CS) and the unconditioned stimulus (US), which requires an array of brain structures to support the formation and storage of associative memory. The entorhinal cortex (EC) has been proposed to provide essential neural code for resolving temporal discontinuity in conjunction with the hippocampus. However, how the CS and TI are encoded at the neuronal level in the EC is not clear.

Central amygdala circuits in valence and salience processing.

Behavioral responses to environmental stimuli are dictated by the affective valence of the stimulus, good (positive valence) or bad (negative valence). These stimuli can innately elicit an affective response that promotes approach or avoidance behavior. In addition to innately valenced stimuli, valence can also be assigned to initially neutral stimuli through associative learning.

Dynamic coding of predatory information between the prelimbic cortex and lateral amygdala in foraging rats.

Predation is considered a major selective pressure in the evolution of fear, but the neurophysiology of predator-induced fear is unknown. We simultaneously recorded lateral amygdala (LA) and prelimbic (PL) area neuronal activities as rats exited a safe nest to search for food in an open space before, during, and after encountering a "predator" robot programmed to surge from afar. Distinct populations of LA neurons transiently increased spiking as rats either advanced or fled the robot, whereas PL neurons showed longer-lasting spike trains that preceded and persisted beyond LA activity.

Increased tone-offset response in the lateral nucleus of the amygdala underlies trace fear conditioning.

Accumulating evidence suggests that the lateral nucleus of the amygdala (LA) stores associative memory in the form of enhanced neural response to the sensory input following classical fear conditioning in which the conditioned stimulus (CS) and the unconditioned stimulus (US) are presented in a temporally continuous manner. However, little is known about the role of the LA in trace fear conditioning where the CS and the US are separated by a temporal gap. Single-unit recordings of LA neurons before and after trace fear conditioning revealed that the short-latency activity to the CS offset, but not that to the onset, increased significantly and accompanied the conditioned fear response.

Alterations of hippocampal place cells in foraging rats facing a "predatory" threat.

Fear is an adaptive mechanism evolved to influence the primal decisions of foragers in "approach resource-avoid predator" conflicts. To survive and reproduce, animals must attain the basic needs (food, water, shelter, and mate) while avoiding the ultimate cost of predation. Consistent with this view, ecological studies have found that predatory threats cause animals to limit foraging to fewer places in their habitat and/or to restricted times.