CROSSMODAL CORTICOCORTICAL PROJECTIONS PREFERENTIALLY TERMINATE IN SUPRAGRANULAR LAMINAE

H Ruth Clemo, M. Alex Meredith
Poster
Time: 2009-06-30  09:00 AM – 10:30 AM
Last modified: 2009-06-04

Abstract


Convergence is the defining step of the multisensory process. Identification of multisensory convergence often first occurs through physiological methods, but the issue of how multisensory properties arise is based on connectivity. Over the years, numerous anatomical studies have been conducted that identify the areal sources of convergent input to established multisensory regions, yet few have assessed the patterns of terminations generated by those inputs. Toward that end, we examined the termination pattern of crossmodal inputs to areas of cat cortex: visual PLLS, somatosensory SIV and RSS, and auditory FAES. Tracer injections (BDA) into afferent sources of these regions consistently revealed orthograde projections that preferentially terminated in the supragranular layers of the target regions. Only the fundic portion of the RSS appeared to deviate from this pattern. This supragranular preference was observed for projections from association, as well as core and belt cortices. Given that the designations of feedback/feedforward are based on studies of intramodal connections, these data suggest that crossmodal projections may follow another set of rules to be identified by further study of the issue of projection termination preferences.

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