The Subplate and Early Cortical Circuits

Abstract

The developing mammalian cerebral cortex contains a distinct class of cells, subplate neurons (SPns), that play an important role during early development. SPns are the first neurons to be generated in the cerebral cortex, they reside in the cortical white matter, and they are the first to mature physiologically. SPns receive thalamic and neuromodulatory inputs and project into the developing cortical plate, mostly to layer 4. Thus SPns form one of the first functional cortical circuits and are required to relay early oscillatory activity into the developing cortical plate. Pathophysiological impairment or removal of SPns profoundly affects functional cortical development. SPn removal in visual cortex prevents the maturation of thalamocortical synapses, the maturation of inhibition in layer 4, the development of orientation selective responses and the formation of ocular dominance columns. SPn removal also alters ocular dominance plasticity during the critical period. Therefore, SPns are a key regulator of cortical development and plasticity. SPns are vulnerable to injury during prenatal stages and might provide a crucial link between brain injury in development and later cognitive malfunction.

Predominant slow EEG activity in healthy neonates: Transient thalamo-cortical dysrhythmia?

“…Kanold and Luhmann, 2010). We propose this may temporarily result in a state of thalamo-cortical dysrhythmia (TCD) wherein the absence of "top-down" cortical modulation results in low-frequency bursting in thalamic neurons, which in turn is propagated to cortical neurons (via projections represented by the solid vertical line).…”

“…see Kanold and Luhmann, 2010). Development of thalamocortical connections, via intermediary subplate neurons initially, occurs during the third trimester.…”

“…Development of thalamocortical connections, via intermediary subplate neurons initially, occurs during the third trimester. Subplate neurons are likewise involved in subsequent development of corticothalamic connections, although this occurs later predominantly after term equivalent age (Kanold and Luhmann, 2010;see Figure1).…”

Secondary expansion of the transient subplate zone in the developing cerebrum of human and nonhuman primates

“…Despite intensive research in various mammalian species in the last 40 y (reviewed in refs. [5][6][7][8][9][10][11], the origin as well as evolutionary and developmental mechanisms that underlie the extraordinary expansion and regional diversification of the SP in human are not well understood (10,12).…”

Parsing out the embryonic origin of subplate cell-type diversity

“…The subplate itself arises together with the cortical plate and marginal zone after splitting from the preplate around E13. This group is extremely diverse and contains both glutamatergic (2) and GABAergic neurons (3), as well as glial cells (4). Their prominence in primates and humans suggests a potentially fundamental role for SNs in the assembly of a multilayered cortical structure and in the development of intercortical connectivity patterns (5).…”