Jun-ichiro Okuda

Lateralization phenomenon of complex auditory hallucinations

Abstract— A case is described of a patient who developed a transient verbal hallucination, lateralized to the right ear, and fluent aphasia after a hemorrhagic infarction in the left superior temporal gyrus. On the basis of this patient and the cases in the literature showing unilateral complex auditory hallucinations, the clinical significance of the lateralization phenomenon of complex auditory hallucinations was investigated. As a result, the lateralization phenomenon of complex auditory hallucinations could be considered a significant clinical sign indicating the existence of a lesion in the superior temporal gyrus opposite the hallucination side.

Dynamin 2 gene is a novel susceptibility gene for late-onset Alzheimer disease in non-APOE-ε4 carriers

AbstractAlzheimer disease (AD) is characterized by progressive cognitive decline caused by synaptic dysfunction and neurodegeneration in the brain, and late-onset AD (LOAD), genetically classified as a polygenetic disease, is the major form of dementia in the elderly. It has been shown that β amyloid, deposited in the AD brain, interacts with dynamin 1 and that the dynamin 2 (DNM2) gene homologous to the dynamin 1 gene is encoded at chromosome 19p13.2 where a susceptibility locus has been detected by linkage analysis. To test the genetic association of LOAD with the DNM2 gene, we performed a case–control study of 429 patients with LOAD and 438 sex- and age-matched control subjects in a Japanese population. We found a significant association of LOAD with single nucleotide polymorphism markers of the DNM2 gene, especially in non-carriers of the apolipoprotein E-ε4 allele. Even though subjects with the genotype homozygous for the risk allele at rs892086 showed no mutation in exons of the DNM2 gene, expression of DNM2 mRNA in the hippocampus was decreased in the patients compared to non-demented controls. We propose that the DNM2 gene is a novel susceptibility gene for LOAD.

Hemispheric asymmetry of processing temporal aspects of repetitive movement in two patients with infarction involving the corpus callosum.

Two right-handed patients with infarction involving the forebrain commissural fibres produced irregular but rapid repetitive movements with their left hands while producing normal movements with their right hands as well as having normal oral expression. The abnormality was more conspicuous when producing slow tapping patterns. When required to reproduce rapid tapping patterns of around 5 beats/sec, one of the patients produced a comparatively regular tapping pattern. Thus, we believe that both hemispheres are equipped with the faculty to produce rapid repetitive patterns and that only the left hemisphere is responsible for the temporal processes involved in producing required repetitive patterns.

A case of slowly progressive aphasia without generalized dementia in a Japanese patient

A Japanse patient with a 4‐year history of slowly progressive aphasia without generalized dementia is described. From 1985 on, this 61‐yr‐old right‐handed dentist showed insidiously progressive deterioration in his speech and auditory comprehension, but has no memory disturbance, disorientation of space, time or persons, acalculia or other impairments in his behavior. His personality changes are unremarkable. He still treats patients at his clinic. General physical and neurological examinations were normal. CT and MRI (1.5T) scans showed widening of the left sylvian fissure and lateral ventricle without any vascular lesions. A PET scan demonstrated focal hypometabolism restricted to the left temporal lobe. The clinical course and picture of our patient corresponds well to those of slowly progressive aphasia without generalized dementia, described by Mesulam.

Auditory extinction to nonverbal and verbal stimuli.

The so‐called auditory extinction phenomenon in a verbal dichotic listening test was investigated in seven brain damaged patients from the qualitative standpoint. As the result, it became evident that the phenomenon could result from competition between verbal materials presented to both ears in at least two different levels of auditory processing i.e., sound perception and linguistic recognition. From the present study, we emphasize the following: 1) If Benders definition is followed, it is advisable to use the term extinction only for the phenomenon at the acoustic level. 2) If the use of the term extinction for the phenomenon is to be continued at the linguistic level, the presence of auditory extinction and/or obscuration to nonverbal stimuli should be noted.

Cerebral Circulation in the Aged with Organic Dementia

一次変性痴呆型 (primary degenerative dementia type=PDD) と, 脳動脈硬化性痴呆型 (arteriosclerotic dementia type=ASD) からなる高年器質性痴呆患者34名 (平均61.2歳) につき, 阪大式老年者用知能テストを用いて痴呆の程度を軽度, 中等度および重度の3段階に分け, また臨床的に上記の2病型に鑑別, 分類した. これらの対象各症例について, 左右の内頚動脈および椎骨動脈血流を超音波ドプラ法により測定し, その流速脈波を分析, 検討してつぎの結果をえた.1) 痴呆の程度が進むにつれて内頚動脈循環血流量は減少する傾向を示した.2) 痴呆患者では, 内頚動脈血流量は右側に比し左側で有意に低下しており, それはとくに重度痴呆群, ASDで顕著であった.3) 流速脈波の波高値を, 心収縮期初期峰 (S1), 第2峰 (S2), incisura (I), 拡張期峰 (D) および拡張末期 (d) の各時期で比較すると, 痴呆の程度が進むにつれ, 内頚動脈でI, D, dにおける最高流速が低下した. また, S1における最高流速はASDに比しPDDで有意に大であった.4) 波高比D/S2およびS2/S1を指標として流速脈波パターンを比較すると, 内頚動脈では痴呆の程度がすすむにつれてD/S2値は低下した. S2/S1比はASDでは年齢相当の値であったがPDDでは若年型を示した. なお椎骨動脈血流は上記の4項目につき痴呆症例間で有意な変化は認められなかった.以上, 高年器質性痴呆患者では, 痴呆の程度にしたがい大脳半球血流量 (ことに左) がとくに心拡張期で減少することが示され, 収縮期における波高比S2/S1はPDDとASDで異なり, 両病型における脳循環動態の相違を示唆するとともに鑑別診断上の指標としても有効であろうと考えられた.

Preserved capacity to copy drawings in severe aphasics with little premorbid experience

Abstract Preserved performances in copying drawings and sketching exhibited by three individuals with severe aphasia and little premorbid experience are described. The patients were aged 84, 66 and 53 years, and were all right-handed. Each had extensive damage to the left hemisphere but little damage to the post-rolandic regions of the right hemisphere. In contrast to the preserved abilities in copying drawings and a two-dimensional cube, all performed poorly in Kohs Block Designs. Two had difficulty in copying their own names. The following conclusions were drawn: (1) among severe aphasics, some patients show superior capability in copying drawings and sketching; (2) it is surmised that the right hemisphere contributes heavily to the manifestation of these capabilities; (3) severe damage to the left hemisphere presumably weakens its interaction with the right hemisphere, whose functions could subsequently be easily and effectively released; (4) the ability of copying drawings may enhanca the quality of l...

Tactile extinction to simple (elementary) and complex stimuli

ABSTRACT‐ Thirty patients with cerebrovascular disease and 85 control subjects were examined using both the classical tactile extinction test and a modified Quality Extinction Test (modified QET) in order to investigate the so‐called tactile extinction phenomenon to complex stimuli from the qualitative standpoint. As a result, 1) the patients with tactile extinction to simple (elementary) stimuli also manifested extinction to complex tactile stimuli in the modified QET; 2) there were patients who exhibited extinction only to complex tactile stimuli. Our results provide support for the concept that the so‐called tactile extinction phenomenon could result from competition between tactile stimuli presented to both hands at at least 2 different levels of tactile processing, i. e. the process of perception and the process of recognition. When discussing the phenomenon of extinction to complex tactile stimuli, therefore, one should consider these 2 forms of extinction separately.

Somatosensory evoked potentials to median nerve stimulation after partial section of the corpus callosum.

SummaryCortical somatosensory evoked potentials (SEPs) to electrical stimulation of the median nerve were studied in four patients with intractable epilepsy who had undergone callosotomy and in a patient with infarction in the corpus callosum in order to determine whether the corpus callosum was involved in the generation of ipsilateral frontal components. Both pre- and postoperative SEPs were recorded in three of four epileptic patients. There were no significant differences in the latencies and amplitudes of the bilateral frontal components (P20, N26) between pre- and postoperative recordings. Furthermore, irrespective of the extent of the section or lesion in the corpus callosum, the nature of the impairment and the existence of the disconnection syndrome, the SEP findings showed no significant differences compared with those of normal subjects. It thus appears unlikely that the ipsilateral SEP responses are transmitted from the contralateral hemisphere through at least the anterior portion of the corpus callosum.