Perisaccadic gamma modulation in Parkinson disease patients and healthy subjects.

We quantified the anterior-posterior distribution of the gamma modulation index (GMI), an index of perisaccadic phasic modulation of the gamma (35-45 Hz) range electroencephalogram (EEG), in healthy human subjects and Parkinson disease (PD) patients. The EEG was recorded over the frontal, parietal, temporal and occipital sites in 11 idiopathic PD patients (age 50-70 years, four females), 4 age matched healthy volunteers (1 female) and 17 young healthy controls (age 21-30 years, four females) Eye movements were recorded with EOG and ISCAN camera. Subjects executed saccades to a mark at right and back to fixation point and vice versa. The saccades directed away from center/fixation (centrifugal CF) were analyzed. Two minutes of EEG were obtained from each subject for the two possible saccade types (centrifugal rightwards and leftwards at 15 degrees). Each perisaccadic EEG segment was analyzed using continuous wavelet transform for quantifying the power and time course of gamma EEG ranges for each saccade type. A three way ANOVA was used for statistical analysis. Perisaccadic GMI (peak intrasaccadic power divided by mean power) in healthy subjects was higher over the contralateral hemisphere to the saccade direction, for both centrifugal saccades at anterior, posterior and occipital recording sites. Contrary to the healthy subject GMI remained near one in PD, i.e., there was no evidence of intrasaccadic gamma power increase in PD patients.

Three dimensional analysis of facial movement in normal adults: influence of sex and facial shape.

The aim of this study was to quantify facial movements in a sample of normal adults and to investigate the influence of sex and facial shape on these movements. The study sample consisted of 50 healthy adult subjects, 25 males and 25 females (age: mean = 27.3 years; range = 23-39 years). A video-based tracking system was used to track small-diameter retroreflective markers positioned at specific facial sites. Subjects were instructed to make 7 maximum facial animations from rest, and the facial movements for each animation were characterized as the vectors of maximum displacement. Hotelling's T2 was used to test for significant sex differences in facial movements. In order to determine the effects of facial shape on facial movements, an index of facial shape was first calculated for each subject, and then a mixed-model ANOVA was used with facial shape (index), sex, and the interaction between facial shape and sex as fixed effects and subject as a random effect. The results demonstrated specific movement patterns for each animation. In general, males had larger movements than females and facial shape had a small but significant effect on facial movements. By comparing patient movements with the data from this large normative sample, the utility of this method to assess region-specific movement deficits was demonstrated.