Functional development of large-scale sensorimotor cortical networks in the brain

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Systems Neuroscience

Background:

• Large-scale neuronal networks integrate cortical areas for complex brain functions like sensorimotor integration.
• The developmental trajectory and functional maturation of these large-scale networks remain poorly understood.
• Understanding how distant neuronal networks become functionally connected during development is a key question.

Purpose of the Study:

• To investigate the functional development of large-scale neuronal networks in the postnatal rat sensorimotor system.
• To identify the maturational processes underlying functional connectivity between distant cortical areas.
• To pinpoint critical developmental time windows for network maturation.

Main Methods:

• Utilized epicranial multielectrode grids covering the cortical surface and intracortical electrodes in postnatal rats.
• Recorded sensory-evoked cortical responses throughout the first three postnatal weeks.
• Analyzed developmental changes in response properties and activity propagation patterns.

Main Results:

• Cortical responses showed continuous maturation over the first three postnatal weeks, with significant changes around postnatal day 13 (P13).
• Before P13, whisker stimulation evoked slow, localized activity in the contralateral parietal area.
• Around P13, a rapid emergence of an early, sharp surface-positive component was observed, coinciding with bilateral sensorimotor area activation.

Conclusions:

• The emergence of a novel cortical response component around P13 signifies functional maturation of supragranular layers.
• This maturational event is critical for establishing functional associations within the large-scale sensorimotor network.
• The observed changes correlate with the onset of whisking behavior and synaptic maturation in the S1 cortex.