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M Y Yazgan

Publications and source records attributed to M Y Yazgan.

4 recordsLinked to original sources

A direct observational measure of whole body turning bias.

The directional preference for spontaneous turning in humans has previously been documented using an electronic device (rotometer). We used a simple, inexpensive, and well-controlled test of turning behaviour in 41 adults with no psychiatric diagnoses. In this test, the direction in which subjects turned is recorded as they complete each one of what they think is a series of evaluations of gait, in a room symmetrically spacious and free of distracters. A substantial majority of our right-handed subjects (N = 27) showed a significant leftward turning bias, while non-right handed group (N = 14) did not show this bias. Test-retest reliability for this measure in 17 individuals tested twice at different times was high (rho = 0.73).

Adult↗

Behavioral laterality in individuals with Gilles de la Tourette's syndrome and basal ganglia alterations: a preliminary report.

This study aims to investigate whether abnormalities in structural basal ganglia asymmetries in Tourette's syndrome (GTS) have functional significance. Eleven adult GTS patients and 11 normal controls who had participated in the previous MRI study where GTS patients lacked the normal left-greater-than-right (L > R) lenticular asymmetry were re-recruited. They were administered a battery of lateralizing neuropsychological tasks believed to require intact basal ganglia function. GTS subjects lacked normal functional asymmetries on these measures, as predicted. The neuropsychological measures also accounted for a significant portion of the variance in the severity of tic symptoms. These findings suggest that GTS subjects who lack normal basal ganglia structural asymmetries also lack normal functional asymmetries on related neuropsychological measures.

Adult↗

Functional significance of individual variations in callosal area.

We considered the hypothesis that the richness of callosal interhemispheric connections has a role in determining the degree of behavioural laterality and time-sharing ability in dual-task performance. Behavioural laterality as measured by dichotic word listening, line bisection and turning bias tests correlated inversely with the midsagittal cross-sectional area of the corpus callosum, as seen on MRI. The amount of dual task interference was strongly inversely correlated with the callosal area in both within-hemisphere and between-hemispheres conditions. These relationships between normal variations in callosal area, and outcomes on tests both of laterally and time-sharing capacity in normal adults suggest that the corpus callosum assumes a cross-excitatory role when subjects perform these tasks.

Adult↗