Differentiated somatic gene expression is triggered in the dorsal hippocampus and the anterior retrosplenial cortex by hippocampal synaptic plasticity prompted by spatial content learning

AbstractHippocampal afferent inputs, terminating on proximal and distal subfields of the cornus ammonis  (CA), enable the functional discrimination of ‘what’ (item identity) and ‘where’ (spatial location) elements of a spatial representation. This kind of information is supported by structures such as the retrosplenial cortex (RSC). Spatial content learning promotes the expression of hippocam pal synaptic plasticity, particularly long-term depression (LTD). In the CA1 region, this is specifically facilitated by the learning of item-place features of a spatial environment. Gene-tagging, by means of time-locked fluorescence in situ hybridization (FISH) to detect nuclear expression of immed iate early genes, can reveal neuronal populations that engage in experience-dependent information encoding. In the current study, using FISH, we examined if learning-facilitated LTD results in subfield-specific information encoding in the hippocampus and RSC. Rats engaged in novel exploration of sma ll items during stimulation of Schaffer collateral-CA1 synapses. This resulted in LTD (>  24 h). FISH, to detect nuclear expression of Homer1a, revealed that the distal-CA1 and proximal-CA3 subcompartments were particularly activated by this event. By contrast, all elements of the proximodistal cornus ammonis-axis showed equal nuclear Homer1a expression following LTD inductionsolely by means of afferent stimulation. The RSC exhibited stronger nuclear Homer1a expression in response t...
Source: Anatomy and Embryology - Category: Anatomy Source Type: research