Histologic evidence for death of cortical neurons after spinal cord transection.

Dying cortical neurons, identified by standard histologic criteria, were observed in the rat sensory/motor cortex after spinal cord transection. The peak incidence of these changes was 10 weeks after injury. At that time, spinal-cord-injured animals showed 10 times as many abnormal cells as were found in matched controls (p less than or equal to 0.05). Dying cells were found in the same anatomic location as corticospinal neurons axotomized by the experimental injury, and at the expected time after injury. The survival of corticospinal neurons in these young adult rats may be dependent on obtaining a crucial input from an appropriate target cell (neuron).