Study of Tactile Sensation Somatotopy and Homology Between Projected Fingers in Residual Limb and Natural Fingers in Intact Limb

• Published in: IEEE transactions on neural systems and rehabilitation engineering Vol. 31; pp. 636 - 645
• Main Authors: Liang, Wenyuan, Qin, Changyu, Sun, Aiping, Zhang, Xuemin, Lan, Ning, Bi, Sheng
• Format: Journal Article
• Language: English
• Published: United States IEEE 2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Amputation; Cognition; Cortex (somatosensory); Electroencephalography; event-related potential (ERP); Event-related potentials; External stimuli; Finger; Fingers; Homology; Indexes; Information processing; Latency; Median nerve; Peripheral nerves; Phantoms; Projected finger mapping (PFM); Prosthetic hand; Sensation; Sensory integration; Skin; Somatosensory; somatosensory mechanism; Statistical analysis; Stimulation; tactile sensation; Thumb; Touch; transcutaneous electrical nerve stimulation (TENS)
• ISSN: 1534-4320; 1558-0210; 1558-0210
• DOI: 10.1109/TNSRE.2022.3229271

Object: Based on the comparisons of the somatosensory event-related potentials (ERPs), the object of this study is to investigate the underlying cognition mechanism of somatotopy and the homology of tactile sensation between the projected fingers in the residual limb and the natural fingers in the intact limb. Methods: One amputee subject and three able-bodied subjects were recruited. The forearm amputee had a clear projected finger mapping (PFM) that could evoke the tactile sensation of the entire five missing fingers. Transcutaneous electrical nerve stimulation (TENS) was used to evoke the sensation pattern of touch. Stimulation locations were divided into three groups: the locations of Group PA (projected-finger of amputee-subject) were located on the entire five projected fingers for the amputee subject, the locations of Group NA (natural-finger of amputee-subject) were located on the entire five natural fingers for the amputee subject, and the locations of Group NH (natural-finger of healthy-subject) were located on the bilateral natural index fingers for the able-bodied subjects. The somatosensory ERPs evoked by the stimulations were recorded. We measured the latency and amplitude of the ERP components and made statistical analyses for them. Main results: Since the ERP components of the early-stage are similar for both the stimulation in the projected fingers and the natural fingers, it can infer that the delivery pathway of the projected finger was similar to that of the natural finger. The second finding of the study is that, as the processing of sensory sensation in the cortex of the three groups is similar, it can also infer that the somatosensory evoked by the external stimuli are also similar. Conclusion: The present findings suggest that the somatotopy and the homology of tactile sensation between the projected fingers in the residual limb and the natural fingers in the intact limb have evident uniformity. We infer that the median nerve and the ulnar nerve of the peripheral nerve may divaricate new pathways, and these pathways would have been linked to the PFM.