Dependence of functional synaptic connections of hippocampal and neocortical neurons on types of memory.

Different types of memory are thought to be processed by different neuronal networks. The present study evaluated the functional synaptic connections among neurons by means of cross-correlation analysis when two types of memory, working and reference memory, were being processed in behaving rats. Some of the synaptic connections of neurons in the hippocampal CA1, CA3, dentate gyrus and auditory cortex functioned when the rat was performing only one of the memory tasks. Working memory needed more of these memory-type dependent synapses in the hippocampal regions than reference memory.