Experience-dependent structural plasticity in cortex heterotopic to focal sensorimotor cortical damage

Area of Science:

• Neuroscience
• Neuroplasticity
• Rehabilitation Science

Background:

• Focal neocortical damage in adult rats shows structural plasticity sensitive to postinjury training.
• Experience with complex motor tasks, like the acrobatic task, after forelimb representation sensorimotor cortex (FLsmc) lesions enhances synaptic changes in contralateral and homotopic cortices.

Purpose of the Study:

• To investigate structural changes in the heterotopic hindlimb representation sensorimotor cortex (HLsmc) following unilateral FLsmc lesions.
• To determine if these changes are influenced by postinjury rehabilitative training on the acrobatic task.

Main Methods:

• Stereological methods using light and electron microscopy were employed.
• Rats underwent unilateral FLsmc lesions or sham operations.
• Postoperative assessment included 28 days of acrobatic training or simple repetitive exercise (motor controls).

Main Results:

• Acrobatic training led to a significant increase in HLsmc cortical volume and layer II/III neuropil and dendritic volume per neuron in the lesioned hemisphere.
• Simple exercise did not induce significant changes compared to sham controls.
• Acrobatic training also prevented cortical volume loss in the HLsmc adjacent to the lesion.

Conclusions:

• Behavioral training post-cortical injury promotes structural plasticity in behaviorally relevant neocortical areas beyond the directly affected homotopic cortex.
• This structural plasticity in heterotopic regions may contribute to behavioral compensation following cortical injury.