Receptive field changes after strokelike cortical ablation: a role for activation dynamics

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Stroke-induced neural reorganization is crucial for functional recovery.
• Two phases of neural reorganization are hypothesized, but their underlying mechanisms remain unclear.
• Computer models suggest immediate dynamic changes followed by synaptic plasticity.

Purpose of the Study:

• To investigate the initial phase of altered cortical function after a small lesion in the macaque middle temporal cortex (area MT).
• To differentiate between dynamic changes and synaptic plasticity in early post-lesion recovery using a combined physiological and computational approach.

Main Methods:

• Physiological recordings from the middle temporal cortex (area MT) in macaques following an experimentally induced cortical lesion.
• Development and application of a neural network computer model to simulate early post-lesion neural activity.
• Integration of immunohistochemical findings to refine the computational model.

Main Results:

• Observed significant receptive field (RF) changes, including expansion and contraction, within the first few days post-lesion.
• The computational model initially reproduced RF expansion but required the inclusion of inhibitory interneuron loss to replicate RF contraction.
• A correlation between increased firing rate and RF size was successfully predicted by the model.

Conclusions:

• Immediate changes in neural activation dynamics, independent of anatomical remodeling, can account for substantial receptive field alterations post-lesion.
• The observed immunohistochemical changes likely represent an immediate extension of the lesion.
• These dynamic changes are sufficient to explain rapid behavioral recovery following middle temporal cortex lesions.