Introduction: The retrosplenial cortex (RSC) has been implicatedin complex cognitive functions such as learning, memory, spatial navigation andintrospection. Dysfunction of RSC is associated with diverse pathologicalconditions such as Alzheimer´s disease, autism or schizophrenia. Thus, addressingthe functional organization and activity of the subdivisions of RSC (areas A29and A30) during the execution of complex cognitive tasks might be relevant for understandingtheir physiological and pathological roles.
Material and Methods: Immunostaining was used for acomprehensive analysis of cFos and EGR-1 expression in RSC and related areas ofmale rats after acquisition and retrieval of contextual fear memory. The impactof MK801 treatment that selectively induces degeneration of layers IV-V neuronsof A29 (A29MK801) was evaluated.
Results: Acquisition and evocation of fear memorypromoted the expression of cFos and EGR-1 in A30, dorsal hippocampus (DH),medial entorhinal cortex (MEnt) and basolateral amygdala (BLA) while EGR-1expression was down-regulated in A29 and caudomedial entorhinal cortex (CEnt). Afterfear conditioning, selective degeneration of A29MK801 neurons impairedfear memory retrieval and prevented cFos and EGR-1 up-regulation in A30,without affecting their expression in DH, MEnt, BLA and CEnt.
Discussion: Theseobservations indicated that RSC integrity is required for fear memory retrieval.The data also showed that fear memory evocation elicits differential neuronalactivation in RSC subdivisions, suggesting that A30 activation depends on thefunctional integrity of A29MK801 neurons.