This study examined the effect of eye movement on the excitability of spinal cord anterior horn cells during movement observation using an eye-tracking device and F-waves. F-waves were elicited from the right abductor digiti minimi (ADM) in 31 healthy subjects. F-waves were first recorded at rest. After a 4-minute rest, F-waves and eye movements were recorded for 1 min while watching a video showing two tasks of the right hand: movements of the little, ring, middle, and index fingers simultaneously (Task A) and movement of the little finger (Task B). The conditions were set to free observation and gaze conditions for these tasks. The F-wave-M-wave (F/M) amplitude ratio and fixation of the little finger were investigated for the two tasks. Statistical analysis was performed using the amplitude F/M ratio relative value and the residence time of the little finger in the region of interest set on the video. The relative F/M amplitude ratio and fixation on the little finger were significantly higher in the gaze condition of task A and all task B than in the free observation condition of task A. These results suggested that gazing at the movement of the little finger increased the excitability of spinal anterior horn cells corresponding to the ADM.

[Aim] To examine relationship between peripheral small fiber dysfunction and large fiber failure in type 2 diabetes mellitus (T2DM), we recorded electrodermal skin conductance (ESC) by Sudoscan (SS), a peripheral C-fiber testing device recently developed in France, and nerve conduction studies (NCS). Since SS is not approved in the Japanese health insurance system, yet, we discuss the usefulness of SS for neuromuscular medicine. [Method] One hundred and sixty-eight patients with T2DM aged under 73 years were included, and those with other causes of peripheral neuropathy were strictly excluded. Nerve conduction studies (NCS) were carried out in the lower limb, and Baba’s diabetic neuropathy criteria (BDC) was applied to evaluate severity of the large fiber dysfunction, since validity and usefulness of BDC has been established by several validation studies. BDC criteria are as follows; BDC-0: no abnormalities by NCS, BDC-1: delay in CMAP, SCV and/or F-wave, BDC-2: fall in Sural SNAP less than 5 μV, BDC-3: fall in tibial CMAP between 2 mV and 5 mV, BDC-4: marked fall in tibial CMAP less than 2 mV. We set 70 μS as a cut off value of the feet ESC, since several large-scale studies and a study with intra-epidermal nerve fiber density of biopsied leg skin revealed 70 μS as a lower limit of healthy subjects. [Results] All subjects complained nothing during SS test. We found that ESC decreased symmetrically, and lower in the feet than in hands. Frequency of abnormally low ESC was seen in 47% of the subjects, while NCS abnormality was revealed in 70%. We confirmed that both frequency and degree of fall in ESC value had positive correlation with advance of BDC (p<0.001). On the other hand, 21% of the subjects with normal NCS (BDC-0 group) had low ESC. [Conclusion] SF dysfunction starts earlier in some T2DM patients, and SF function declines in parallel with development of LF dysfunction. Sudoscan is a useful tool to detect small C-fiber dysfunction emerging in early stage of DPN. Although SS is not approved in the Japanese health insurance medical system, yet, early adoption of SS is desired.

With Japan’s rapidly aging population and declining birthrate, the number of patients with dementia diseases is rapidly increasing, and inexpensive, simple, yet highly accurate screening tests for dementia diseases are needed. EEG is expected to be a low-cost, non-invasive biomarker in clinical practice for dementia diseases due to its sensitivity to brain activity and ease of access. This paper outlined the conventional neurophysiological findings on dementia diseases and introduced the attempts to apply artificial intelligence to EEG data for automatic analysis, as well as the use of sheet-type electroencephalographs that can be easily measured. By making full use of these new technologies, developments such as their use in screening tests for dementia diseases can be expected.