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Biomedical subjects

F F Sarazin

Publications and source records attributed to F F Sarazin.

4 recordsLinked to original sources

Fifteen-year stability of some neuropsychological tests in learning disabled subjects with and without neurological impairment.

The stability of the WISC/WAIS-R and seven other commonly used neuropsychological tests over a period of 15 years was investigated in 133 learning-disabled subjects, and for subgroups with hard neurological signs, soft neurological signs, and without neurological findings. Results showed high and significant correlation coefficients between time 1 (mean age 10 years) and time 2 (mean age 25 years), even though for some tests a change from the children's to the adult version occurred. Using a repeated-measures multivariate design, the three subgroups did not differ on this limited test battery. The correlation coefficients for the three subgroups provide an estimate of the range of stability in three different samples.

Achievement↗

Event-related potentials during naming and mental rotation.

The biphasic late negative wave (Nx-Ny) evoked during the naming of pictures of objects was investigated in a series of experiments. The monitoring of several possible non-cerebral generators indicated that these components were probably cerebral in origin. The Ny wave differed in scalp distribution from the preceding CNV. It was unaffected by stimulus duration or by stimulus repetition. The Nx-Ny complex occurred in both a naming task and a mental rotation task. The slow waves following the biphasic negative wave differed significantly between these two tasks. In the mental rotation task, there was a large prolonged negativity in both parietal regions. The Nx wave (at approximately 250 msec) of the biphasic complex may represent the initial registration of the stimulus. The Ny wave (at approximately 420 msec) does not appear to be specifically related to semantic processing. Rather it may index some process involved in initiating the further evaluation of a complex stimulus. The slow waves that follow the biphasic negative complex may reflect the actual perceptual processing of the stimulus.

Brain↗

Evidence for the involvement of orbitofrontal cortex in memory functions: an interference effect.

Although it is frequently stated that the frontal lobes play a significant role in memory function, research proof has been ambiguous at best. This problem was addressed by administering a variety of memory tests to 16 schizophrenic patients who had undergone prefrontal leucotomy approximately 25 years earlier. The 16 were divided into three groups on the basis of recovery after surgery. Two comparison groups were established to control for psychiatric symptomatology, years of institutionalization, age, and years of education. The results demonstrate that large bilateral orbitofrontal lesions may not result in amnesia; in fact, the nonoperated schizophrenic control group performed the most poorly. Proactive interference was demonstrated, however, resulting in significant impairment for all patients with prefrontal lobe damage despite normal scores on commonly used memory tests. Ability to maintain consistent and directed attention and to overcome interference is proposed as a role of the frontal lobes in memory function.

Amnesia, Retrograde↗