Behavioral neuroscience
-
Behavioral neuroscience · Jun 2009
Separate signals for orthonasal vs. retronasal perception of food but not nonfood odors.
There is a controversy concerning whether smelling via the nose (ortho-nasally) or the mouth (retro-nasally) represent two routes to the same modality or two distinct submodalities. Since olfactory coding is dependent upon experience, and since food odors are experienced retro-nasally, the authors tested the hypothesis that whether an odor represents a food may influence whether sensation via the two routes leads to separable responses. ⋯ This effect is specific, in that it does not depend on differences in odor intensity or pleasantness and is selective, in that it occurs for food odors but not for equally pleasant and intense nonfood odors. These results demonstrate that separable signals are generated for the same food odor depending upon route and support the existence of category-specific processing.
-
Behavioral neuroscience · Oct 2008
Timing of extinction relative to acquisition: a parametric analysis of fear extinction in humans.
Fear extinction is a reduction in conditioned fear following repeated exposure to the feared cue in the absence of any aversive event. Extinguished fear often reappears after extinction through spontaneous recovery. Animal studies suggest that spontaneous recovery can be abolished if extinction occurs within minutes of acquisition. ⋯ In the single cue paradigm, the Immediate and Delayed groups exhibited differences in context, but not fear, conditioning. With differential conditioning, there were no differences in context conditioning and the Immediate group displayed less spontaneous recovery. Thus, the results remain inconclusive regarding spontaneous recovery and the timing of extinction and are discussed in terms of performing translational studies of fear in humans.
-
Behavioral neuroscience · Oct 2008
Neural dynamics underlying impaired autonomic and conditioned responses following amygdala and orbitofrontal lesions.
A neural model is presented that explains how outcome-specific learning modulates affect, decision-making, and Pavlovian conditioned approach responses. The model addresses how brain regions responsible for affective learning and habit learning interact and answers a central question: What are the relative contributions of the amygdala and orbitofrontal cortex to emotion and behavior? In the model, the amygdala calculates outcome value while the orbitofrontal cortex influences attention and conditioned responding by assigning value information to stimuli. Model simulations replicate autonomic, electrophysiological, and behavioral data associated with three tasks commonly used to assay these phenomena: Food consumption, Pavlovian conditioning, and visual discrimination. Interactions of the basal ganglia and amygdala with sensory and orbitofrontal cortices enable the model to replicate the complex pattern of spared and impaired behavioral and emotional capacities seen following lesions of the amygdala and orbitofrontal cortex.
-
Behavioral neuroscience · Jun 2008
Oxytocin receptor activity in the ventrocaudal periaqueductal gray modulates anxiety-related behavior in postpartum rats.
Postpartum rats are less anxious than diestrous virgin females, a phenomenon requiring that mothers have recent contact with their infants. Oxytocin (OT) is one of many neurochemicals released intracerebrally while mothers interact with infants, and we investigated whether OT receptor activity in the ventrocaudal periaqueductal gray (cPAGv) contributes to mothers' reduced anxiety. ⋯ OTergic manipulations inconsistently affected risk-assessment behaviors (stretch-attend postures, head dips) in both virgins and dams. Therefore, OT receptor activation in the cPAGv is an important consequence of contact with infants that reduces some anxiety-related behaviors in mother rats.
-
Behavioral neuroscience · Feb 2007
Predator odor-induced conditioned fear involves the basolateral and medial amygdala.
The basolateral (BLA) and medial nucleus (MeA) of the amygdala participate in the modulation of unconditioned fear induced by predator odor. However, the specific role of these amygdalar nuclei in predator odor-induced fear memory is not known. Therefore, fiber-sparing lesions or temporary inactivation of the BLA or MeA were made either prior to or after exposure to cat odor, and conditioned contextual fear behavior was examined the next day. ⋯ In addition, temporary pharmacological neural inactivation methods occurring after exposure to cat odor revealed subtle behavioral alterations indicative of a role of the BLA in fear memory consolidation but not memory retrieval. In contrast, the MeA appears to play a specific role in retrieval but not consolidation. Results show that the BLA participates in the conditioned and unconditioned cat odor stimulus association that underlies fear memory, underscore a novel role of the MeA in predator odor contextual conditioning, and demonstrate different roles of the BLA and MeA in modulating consolidation and retrieval of predator odor fear memory.