Deficits in Behavioral Functions of Intact Barrel Cortex Following Lesions of Homotopic Contralateral Cortex

Area of Science:

• Neuroscience
• Sensory processing
• Behavioral plasticity

Background:

• Unilateral focal injuries to the somatosensory whisker cortex induce lasting neuronal deficits in the contralateral cortex.
• The long-term impact of these deficits on the behavioral functions of the intact cortex remains unclear.

Purpose of the Study:

• To investigate the long-term effects of unilateral somatosensory cortex lesions on the behavioral functions of the intact cortex.
• To test if such lesions degrade the execution of a bilaterally learned behavior using the whisker-sensitive Gap-crossing task.

Main Methods:

• Adult rats were trained on the bilateral Gap-crossing task.
• Unilateral barrel cortex lesions were induced via subpial aspiration.
• Performance deficits were assessed using whiskers projecting to lesioned and intact cortices, and in normal rats under unilateral or reduced whisker input conditions.

Main Results:

• Lesioned rats showed severe deficits using whiskers projecting to the lesioned hemisphere.
• Significant, persistent deficits were observed when lesioned rats used whiskers projecting to the intact cortex, especially at high sensitivity levels.
• Normal rats performing the task with unilateral or reduced whisker input exhibited comparable deficits.

Conclusions:

• Sensory input from a single set of whiskers to the intact cortex is insufficient for optimal performance at high detection thresholds.
• Optimal somatosensory behavior requires dynamic, interhemispheric interactions between homotopic cortical areas.
• Unilateral cortical injuries likely cause widespread bilateral effects on information processing, impacting intact cortical areas.