Zoltán Molnár - Neuroscience - 'Earliest Thalamocortical Interactions'

Conscious perception in mammals depends on precise circuit connectivity between cerebral cortex and thalamus. During the wiring of reciprocal thalamus-cortex connections, thalamocortical axons (TCAs) first navigate forebrain regions that had undergone substantial evolutionary modifications. In mammals, transient cell populations in internal capsule and early corticofugal projections from subplate neurons closely interact with TCAs to guide pathfinding through ventral forebrain and pallial subpallial boundary (PSPB) crossing. Prior to TCA arrival, cortical areas are initially patterned by intrinsic genetic factors. TCAs then innervate cortex in a topographically organised manner to enable sensory input to refine cortical arealization. We investigate the mechanisms underlying the reciprocal influence between thalamus and cortex during development in rodent and in human. We recently demonstrated that these axons exhibited a close anatomical relationship with the existing germinal compartments in human. By 17 PCW, TCA did not only reach the transient subplate, a well-known target for thalamic axons in the mammalian brain, but also appeared to project toward the outer subventricular zone (OSVZ). We are using transcriptomic and proteomic approaches to explore the unique target compartments of the developing cortex, such as the OSVZ and suplate. We recently identified candidates that could mediate these interaction through paracrine mechanisms by secretion of neuroactive peptides.