Yonsei University · Medicine
Professor Young H. Sohn's research lab specializes in the neurophysiological mechanisms underlying movement disorders, with a focus on cortical inhibition, motor control, and neurodegenerative diseases. The lab investigates pathophysiological mechanisms such as impaired surround inhibition in focal hand dystonia and white matter damage in conditions like carbon monoxide poisoning and multiple system atrophy. Using non-invasive brain stimulation techniques like transcranial magnetic stimulation (TMS), the lab explores cortical excitability and inhibitory circuits in both healthy individuals and patients with Parkinson’s disease, restless legs syndrome, and other neurological conditions. The lab also examines the potential of mesenchymal stem cell (MSC) therapy as a neuroprotective intervention in neurodegenerative disorders.
Figures are computed from collected data and may differ slightly.
Disturbances in surround inhibition could account for various movement disorders. Here we test the functional operation of surround inhibition in focal hand dystonia. Transcranial magnetic stimulation was set to be triggered by self-initiated voluntary flexion of the index finger. During this movement, motor-evoked potential amplitudes from the little finger muscle were significantly suppressed in healthy subjects but enhanced in dystonia patients. This result supports the idea that disturbed su
MSC therapy could delay the progression of neurological deficits in patients with MSA-C, suggesting the potential of MSC therapy as a treatment candidate of MSA.
To investigate the effect of volitional inhibition on cortical inhibitory mechanisms, we performed transcranial magnetic stimulation (TMS) studies with a Go/NoGo reaction task in seven healthy subjects. Subjects were asked to extend their right index finger only after Go, but to remain relaxed after NoGo. Single- and paired-pulse TMS were triggered at the average reaction time for the Go response in each subject after Go or NoGo cues. Motor evoked potentials were recorded in the extensor indicis
These results support the role of white matter damage in producing parkinsonism after CO poisoning and highlight the possible usefulness of magnetic resonance spectroscopy in predicting delayed sequelae in patients after CO poisoning. Arch Neurol. 2000;57:1214-1218
Although restless legs syndrome (RLS) commonly accompanies Parkinson disease (PD), the mechanism of RLS development in PD is still unclear. We investigated the prevalence of RLS in Korean patients with PD, and the possible contributing factors to the development of RLS in those patients. Four hundred forty-seven consecutive patients with PD were interviewed and examined. Among them, 73 patients (16.3%) were diagnosed with RLS. PD patients with RLS had a longer duration of PD symptoms, more sever
These results suggest that LTC reduces the corticospinal neuronal response to magnetic stimulation, preferentially affecting less excitable neurons. The lack of change in F-wave and CMAP suggests that this effect is mainly derived from the motor cortex.
These results suggest that dominant-side patients have greater neural reserve, allowing them to better cope with PD-related pathological changes (i.e., fewer motor deficits despite similar dopamine reduction) compared to non-dominant-side patients.
The present study revealed the functional brain network associated with motor reserve in patients with early-stage PD. Functional connections within the motor reserve network are associated with the individual's capacity to cope with PD-related pathologies. © 2020 International Parkinson and Movement Disorder Society.
To investigate the effect of negative motor imagery on corticospinal excitability, we performed transcranial magnetic stimulation (TMS) studies in seven healthy subjects during imagination of suppressing movements. Subjects were asked to imagine suppression of TMS-induced twitching movement of their nondominant left hands by attempting to increase the amount of relaxation after receiving an auditory NoGo cue (negative motor imagery), but to imagine squeezing hands after a Go cue (positive motor
In order to investigate the clinical impact of polymyographic evaluation on the diagnosis of propriospinal myoclonus (PSM), we performed electromyography recordings of various truncal muscles in eight healthy volunteers while they mimicked PSM symptoms. Before the experiment, each volunteer learned how to mimic PSM by watching a videotape that showed typical PSM characteristics, i.e., brief symmetric flexion of the trunk. The recorded polymyographic patterns of all volunteers were quite compatib
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