The cortical component of experience-dependent synaptic plasticity in the rat barrel cortex

Area of Science:

• Neuroscience
• Sensory processing
• Synaptic plasticity

Background:

• Rats raised with single vibrissa (D1-spared animals) exhibit altered cortical barrel responses to tactile stimulation.
• Previous studies indicated enhanced responses to the spared D1 vibrissa and reduced responses to principal vibrissae.

Purpose of the Study:

• To investigate the location and nature of synaptic plasticity underlying altered sensory responses in D1-spared rats.
• To determine if plasticity occurs within the barrel cortex or at subcortical levels.
• To examine the role of inter-barrel connections in mediating these changes.

Main Methods:

• Induction of univibrissa rearing in rats from postnatal day 0.
• Acute microlesions were made within the D1 barrel and the septum between barrels.
• Electrophysiological recordings measured neuronal responses to D1 and principal vibrissa stimulation.

Main Results:

• Microlesions in the D1 barrel attenuated potentiated D1 responses, indicating cortical plasticity.
• Lesions in the septum between barrels abolished D1 responses in adjacent barrels, suggesting involvement of inter-barrel pathways.
• Short-latency responses were dependent on intact septal connections, implying plasticity in radiating pathways.

Conclusions:

• Synaptic plasticity in D1-spared rats occurs within the barrel cortex, not subcortically.
• Plasticity involves changes in synaptic connections within the D1 barrel and in pathways radiating to adjacent barrels.
• Univibrissa rearing induces adaptive changes in cortical sensory processing through local and network-level plasticity.