Changes in the P300 component of the tactile event-related potential following spinal cord injury

Previous studies have demonstrated that significant changes in action or behaviour (function) and morphology occur in the deafferentated and the adjacent somatosensory cortex after amputation or experimental spinal cord injury. These studies have shown changes in somatotopic mappings and somatosensory perception as well as altered evoked responses. The purpose of the present study was to examine the potential effect of these changes on cognitive processes using the tactile P300 event-related potential (ERP) in a spinal cord injured (SCI) population. The P300 ERP has been associated with more complex cognitive functioning such as selective attention, memory, and stimulus evaluation rather than earlier sensory processing of stimuli. Three groups consisting of healthy control, paraplegic, and tetraplegic subjects participated in a transcutaneous electrical stimulation 'oddball' task. Results indicate that all groups were successful in maintaining target counts and produced significantly larger P300 amplitudes with longer latencies to target trials compared to non-target trials. The SCI groups, however, produced P300 ERPs for both targets and non-targets that were significantly reduced in amplitude compared to the control group. In the case of the tetraplegia patients, the P300 was almost abolished. No differences in latency of the P300 was observed between any of the groups.