PubMed Health⌕ Search

PubMed · 10195132

Orbitofrontal cortex and basolateral amygdala encode expected outcomes during learning.

Abstract

Reciprocal connections between the orbitofrontal cortex and the basolateral nucleus of the amygdala may provide a critical circuit for the learning that underlies goal-directed behavior. We examined neural activity in rat orbitofrontal cortex and basolateral amygdala during instrumental learning in an olfactory discrimination task. Neurons in both regions fired selectively during the anticipation of rewarding or aversive outcomes. This selective activity emerged early in training, before the rats had learned reliably to avoid the aversive outcome. The results support the concept that the basolateral amygdala and orbitofrontal cortex cooperate to encode information that may be used to guide goal-directed behavior.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

G Schoenbaum, A A Chiba, M Gallagher. 1998. Orbitofrontal cortex and basolateral amygdala encode expected outcomes during learning.. https://doi.org/10.1038/407

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

The influence of chemosensory input and gonadotropin releasing hormone on mating behavior circuits in male hamsters.

Chemosensory input is important for mating behavior in male hamsters. Chemosignals found in female hamster vaginal fluid activate regions of the brain that receive input from the vomeronasal/accessory olfactory system and are important for mating behavior. Mating or exposure to these chemosignals produces increased Fos protein expression in the amygdala, bed nucleus of the stria terminalis, and medial preoptic area (MPOA). These brain regions contain cell bodies and/or fibers of gonadotropin releasing hormone (GnRH) neurons, suggesting potential relationships between chemosensory systems and GnRH. GnRH is released naturally when male rodents (mice and hamsters) encounter female chemosignals, and intracerebrally injected GnRH restores mating behavior in sexually naive male hamsters after removal of the vomeronasal organs. We report here that the combination of pheromone exposure and intracerebrally-injected GnRH increases Fos expression in the MPOA above the increase seen in pheromone-exposed males, or in males given only the exogenous GnRH. In males with vomeronasal organs removed (VNX), there was an also an increment in Fos expression in the MPOA when these pheromone exposed males were injected with GnRH, provided they had previous sexual experience. Males with vomeronasal organs removed and without sexual experience showed increased Fos expression in the medial amygdala when pheromone exposure and GnRH injection were combined, but not in the medial preoptic area.

Amygdala↗

Identification of cerebral neurons and glial cell types inducing heat shock protein Hsp70 following heat stress in the rat.

Heat shock proteins were recently recognized as molecular chaperones that besides their chaperoning function were also involved in processes of cell death and survival. Many types of neural cells were reportedly capable of expressing heat shock protein Hsp70 following heat stress in vitro. However, identification of cell types inducing Hsp70 protein in the hyperthermic brain is not clear. In this study, cerebral Hsp70 distribution was evaluated in anesthetized adult rats (urethane, 1.5 g/kg, i.p.) subjected to short-term hyperthermia (41.5 degrees C for 30 min). Detection of Hsp70 was achieved by an ABC technique in vibratome or paraffin sections combined with specific markers of glial cell types. Hsp70 appeared by 90 min, mainly in glial and vascular cells, with enhanced immunostaining by 4 h following hyperthermia. Higher numbers of Hsp70-positive cells were detected in the white matter and diencephalic region than in the cerebral cortex, especially over the shorter interval. Hsp70 was localized in many oligodendrocytes, double-labeled with lectin GSII, and some vessels. Microglia showed apparently less Hsp70/OX-42 double-labeled cells than the previous two cell types. In contrast, only a few Hsp70-stained cells were positive for astrocyte marker GFAP. In addition to glial/vascular Hsp70 staining, neuronal Hsp70 induction was observed only in discrete regions including the paraventricular, supraoptic, suprachiasmatic and other hypothalamic nuclei, and in amygdala. Prevailing heat-stress expression of Hsp70 in oligodendrocytes and vascular cells might render them less susceptible to the consequences of other types of cell stress and could be exploited to increase selectively their survival in pathological situations.

Amygdala↗

The study of spatial memory in adult male rats with injection of testosterone enanthate and flutamide into the basolateral nucleus of the amygdala in Morris water maze.

Extensive evidence suggests that the amygdala is involved in memory. The presence of androgenic and estrogenic receptors in the amygdala may reflect a possible involvement in certain activities of this part of the brain. Since sex steroids are known to play role in the maintenance and modulation of behavior, particularly spatial cognition throughout the life span, it was interesting to explore the role of these receptors in spatial memory. Therefore, an experiment was designed to investigate the effect of testosterone enanthate as an agonist and flutamide as an antagonist of androgenic receptors on spatial memory and learning. Wistar rats were bilaterally cannulated into basolateral nucleus of amygdala. Animals in different groups including vehicle (dimethyl sulfoxide) were proven to be inert for memory and learning. Testosterone enanthate (20, 40, 80 and 120 microg/0.5 microl), and flutamide (2, 5, 10, 20 and 40 microg/0.5 microl) were injected in both cannulae 30 min before each training day. After 4 days of experiments, results indicate a dose-dependent increase in parameters of escape latencies and travel distances to find the invisible platform in the group that received 120 microg/0.5 microl testosterone enanthate as compared to the control and vehicle groups. Flutamide had no effect on spatial memory. Therefore, it appears that androgens may effect memory and learning in amygdala. This is a feature that requires further investigation.

Amygdala↗