Purpose: Sensory feedback for prosthetics is an important issue. The area of forearm stump skin that has evoked tactile sensation (ETS) of fingers is defined as the projected finger map (PFM), and the area close to the PFM region that does not have ETS is defined as the non-projected finger map (NPFM). Previous studies have confirmed that ETS can restore the tactile pathway of the lost finger, which was induced by stimulation of transcutaneous electrical nerve stimulation (TENS) on the end of stump skin. This study aims to reveal EEG features between the PFM and the NPFM regions of the stumps under the same TENS stimulation condition.Methods: The PFM and NPFM regions of the two subjects were stimulated with the same intensity of TENS, respectively. TENS as target stimuli are modulated according to the Oddball paradigm to evoke the P300 components.Result: The PFM regions of both subjects were able to elicit P300 components, while their NPFM regions were not able to elicit P300 components. However, this P300 appears early (249 ms for subject 1,230 ms for subject 2) and has continuous positive peaks (peak 1,139 ± 3 ms, peak 2,194 ± 0.5 ms) in front of it.Discussion: N30 and P300 can prove that the two subjects with PFM can perceive and recognize ETS. The heteromorphisms of the P300 waveform may be related to the difficulty in subjects’ cognition of ETS or caused by the fusion of P150, P200, and P300.

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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

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