Cortical somatosensory-evoked potentials in the horse.

This research study investigates the cortical somatosensory-evoked potentials (SEP) in horses, specifically from the thoracic and pelvic limbs, and reports on the latencies and amplitude variabilities of these neural responses.

Understanding Cortical Somatosensory-Evoked Potentials

• The cortical somatosensory-evoked potentials (SEP) are electrical signals produced in response to sensory stimuli, specifically measured from the somatosensory cortex, a part of the brain that processes sensory information from the body. This research examines these SEPs in horses.

Method of Investigation

• The researchers studied 15 horses (13 Thoroughbreds and 2 Quarter Horses) for the investigation.
• They induced ulnar nerve SEP by electrically stimulating the lateral palmar branch of the ulnar nerve at the metacarpophalangeal joint level, located in the hoof.
• Similarly, the tibial nerve SEP were evoked by stimulating the lateral plantar nerve branch of the tibial nerve at the metatarsophalangeal joint level.
• The researchers recorded these responses using electrodes placed at specific points on the horse’s head.

Findings

• In all the recordings, four peaks (N1, P1, N2, P2) were identified. These peaks represent different stages or points in time of the neural response post-stimulation.
• The latency, or time delay from the point of stimulus to each peak, was recorded.
• The variation or ‘spread’ in these latency values, that is, the standard deviation, was also calculated.
• The study found that the latency to the peaks was 39.0 +/- 2.7, 45.5 +/- 5.3, 50.4 +/- 5.2, and 62.3 +/- 3.7 ms for ulnar nerve SEP, and 64.6 +/- 11.8, 84.5 +/- 9.7, 121.2 +/- 11.6, and 134.0 +/- 11.1 ms for tibial nerve SEP, respectively.
• The variability of the amplitude, or ‘height’ of these neural responses, was found to be high for both the ulnar and the tibial nerve SEPs.
• The research found no effect of sex on peak latency or amplitude, and peak latencies were not affected by body length.

Significance of the Study

• This research provides foundational data on the neural responses from the sensory regions in horses.
• Such information can be critical for understanding and diagnosing neurological issues or conditions in these animals.