Relationship between EEG dimensional complexity and neuropsychological findings in Alzheimer's disease.

The aim of the present study was to examine the region-specific correlations between electroencephalography (EEG) dimensional complexity (DC), a measure of non-linear dynamics, and neuropsychological performance in 25 right-handed patients with Alzheimer's disease (AD). Electroencephalography recording sites were according to the international 10-20 system. Neuropsychological tests included Wechelor Adult Intelligence Scale-Revised (WAIS-R) (Full-scale Intelligence Quotient (FIQ), Verbal Intelligence Quotient (VIQ), Performance Intelligent Quotient (PIQ)); Mini-Mental State Examination; Raven's Coloured Progressive Matrices (RCPM); Rey Auditory-Verbal Learning Test (RAVLT); seven word pairs-revised Miyake Paired-Associate Word Learning Test; Benton Visual Retention Test; and Rey Complex Figure Test. A partial correlational analysis was carried out, controlling for age and sex (P< 0.005). The FIQ, VIQ and RCPM scores were found to be significantly correlated with DC at the F3, C3 and T3 electrodes. Significant correlations were also found between RAVLT scores and DC at the C3, P3 and T5 electrodes. The study on AD indicated region-specific correlations between DC and neuropsychological performance: one between the DC value in the left frontal, central and mid-temporal areas and intellectual function; and another between the DC value in the left central, parietal and post-temporal areas and verbal memory. Dimensional complexity would therefore seem to be a useful indicator for the assessment of neuropsychological deficits in AD.

Semantic priming in patients with Alzheimer and semantic dementia.

Semantic priming for pairs of words having semantic relation (members of the same category) but not associative relation was tested in four patients with mild Alzheimer-type dementia (AD), three patients with semantic dementia (SD) and three normal controls. Priming effects were exhibited by all the AD patients and normal controls but by none of the SD patients. The facilitation did not differ depending on whether words were written in kanji or kana. The nature of semantic deficits in AD and SD is discussed.

Pure amnesia caused by bilateral temporal lobe astrocytoma--case report.

A 32-year-old male presented with progressive pure amnesia caused by astrocytoma invading the bilateral medial temporal lobes. Methionine positron emission tomography demonstrated the extent of tumor invasion well. His memory impairment was partially improved by treatment for the astrocytoma. Lesion of the bilateral hippocampus causes memory impairment, but pure memory loss without other associated neurological sign or deterioration of consciousness is rare in a case of cerebral neoplasm.

Dissociations between reading responses and semantic priming effects in a dyslexic patient.

We report a patient (Y.Y.) with senile dementia of the Alzheimer's type. The patient read aloud some words composed of two or three kanji characters with errors applying typical pronunciations of each character and defined them in keeping with the mispronunciation if the pronunciation represented another real word. The results of single-word semantic priming in a lexical decision task, however, suggested normal recognition processes for these kanji-words, despite the patient's reading errors. We consider her reading to represent surface dyslexia in Japanese. We discuss these dissociations between reading responses and priming effects in the context of dual-route models of human reading, and conclude that the "visual route" (direct access from orthography to semantics and phonology) was not completely disrupted, but partially preserved and functioning in automatic access.