Learning‐associated regulation of polysialylated neural cell adhesion molecule expression in the rat prefrontal cortex is region‐, cell type‐ and paradigm‐specific

Abstract

The prefrontal cortex (PFC) is an interconnected set of cortical areas that function in the synthesis of a diverse range of information and production of complex behaviour. It is now clear that these frontal structures, through bidirectional excitatory communication with the hippocampal formation, also play a substantial role in long-term memory consolidation. In the hippocampus, morphological synaptic plasticity, supported by regulation of neural cell adhesion molecule (NCAM) polysialylation status, is crucial to information storage. The recent description of polysialylated neurons in the various fields of the medial PFC suggests these structures to possess a similar capacity for synaptic plasticity. Here, using double-labelling immunohistochemistry with glutamic acid decarboxylase 67, we report that the nature of NCAM polysialic acid-positive neurons in the PFC is region-specific, with a high proportion (30-50%) of a gamma-aminobutyric acid (GABA)ergic phenotype in the more ventral infralimbic, orbitofrontal and insular cortices compared with just 10% in the dorsal structures of the cingulate, prelimbic and frontal cortices. Moreover, spatial learning was accompanied by activations in polysialylation expression in ventral PFC structures, while avoidance conditioning involved downregulation of this plasticity marker that was restricted to the dorsomedial PFC--the cingulate and prelimbic cortices. Thus, in contrast to other structures integrated functionally with the hippocampus, memory-associated plasticity mobilized in the PFC is region-, cell type- and task-specific.

A genome-wide scan for common alleles affecting risk for autism

“…Inactivation of ST8SiaII in mice alters axonal targeting, involving hippocampal infrapyramidal mossy fibers, and the mice show increased exploration and diminished fear (40,41), behaviors of potential relevance to autism. Learning and memory, mediated through morphological synaptic plasticity, are also critically dependent on NCAM polysialylation status but in a complex way (42). Further studies are needed to determine the relevance of these neurodevelopmental results to the genetics of autism and identify the genetic variation affecting expression or function of ST8SIA2 .…”

Role of polysialylated neural cell adhesion molecule in rapid eye movement sleep regulation in rats

“…Furthermore, PSA NCAM levels have been shown to increase in an activity‐dependent manner in several brain regions after stimulation, for example in the hippocampus and prefrontal cortex after learning (Lopez‐Fernandez et al. , 2007; Ter Horst et al. , 2008), and in the suprachiasmatic nucleus (SCN), the site of the principal circadian clock in mammals, after brief photic stimulation (Glass et al.…”