Biomedical subjects

M Delong

Publications and source records attributed to M Delong.

3 recordsLinked to original sources

PubMed2006

Normalizing motor-related brain activity: subthalamic nucleus stimulation in Parkinson disease.

OBJECTIVE: To test whether therapeutic unilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients with Parkinson disease (PD) leads to normalization in the pattern of brain activation during movement execution and control of movement extent. METHODS: Six patients with PD were imaged off medication by PET during performance of a visually guided tracking task with the DBS voltage programmed for therapeutic (effective) or subtherapeutic (ineffective) stimulation. Data from patients with PD during ineffective stimulation were compared with a group of 13 age-matched control subjects to identify sites with abnormal patterns of activation. Conjunction analysis was used to identify those areas in patients with PD where activity normalized when they were treated with effective stimulation. RESULTS: For movement execution, effective DBS caused an increase of activation in the supplementary motor area (SMA), superior parietal cortex, and cerebellum toward a more normal pattern. At rest, effective stimulation reduced overactivity of SMA. Therapeutic stimulation also induced reductions of movement related "overactivity" compared with healthy subjects in prefrontal, temporal lobe, and basal ganglia circuits, consistent with the notion that many areas are recruited to compensate for ineffective motor initiation. Normalization of activity related to the control of movement extent was associated with reductions of activity in primary motor cortex, SMA, and basal ganglia. CONCLUSIONS: Effective subthalamic nucleus stimulation leads to task-specific modifications with appropriate recruitment of motor areas as well as widespread, nonspecific reductions of compensatory or competing cortical activity.

Adult↗

PubMed1995

Perception testing of apparel ease variation.

The development of new computer technologies designed to custom-fit apparel has created a need for quantification of apparel fit characteristics. Fit perception and preference data are needed to improve sizing for ready-to-wear and custom-fitted apparel. Tactile responses of subjects to the fit of pants were investigated using an adaptation of an American Society for Testing and Materials (ASTM) sensory perception test. The test was designed to establish thresholds in apparel fit: that is, the smallest difference in garment dimensions that can be consistently perceived and identified. The test samples for the study were a set of 15 pants, which varied in size, made for each participant from precise computer-generated patterns. Four female experts in apparel fit, who comprised the subject panel, each recorded their responses to these pants compared to a control. Control pants were custom-fitted to each panel member; the remaining pants in each set varied from the control by 0.5 to 1.5 cm at a single location (waist, hips, or crotch length). When the pants were presented in a blind test, the panel perceived differences as small as 0.5 cm in pants waist size from the control. Differences of 1.5 cm were perceptible at the hip and crotch. The subject's level of acceptance of the fit variations in the pants was then judged using a preference test. This test revealed differences among individual subjects in the acceptability of fit variations in waist and crotch dimensions; judgements of the acceptability of hip variations were more consistent among the subjects. Judging from the results of this testing, it is concluded that threshold levels at which fit differences can be perceived can be established for different areas of the body, and that perceptible fit variations can be quite small. This testing also showed that individuals vary in their tolerance for fit variations at different locations on the body.

Journal Article↗

PubMed1989

Microphysiological recordings at CT gantry site during stereotactic thalamotomy.

Neural unit recording was performed during CT-guided stereotactic thalamotomy in 2 patients referred for severe cerebellar ataxia and dysmetric movements. Periodic CT scanning was performed during the recording in order to verify probe location and trajectory. Our experience with electrophysiological recordings at the CT gantry site demonstrates the feasibility of acquiring satisfactory neural unit recordings in spite of the high-voltage environment.

Brain↗