PubMed Health⌕ Search

Biomedical subjects

Katsuhiko Takeda

Publications and source records attributed to Katsuhiko Takeda.

9 recordsLinked to original sources
PubMed2005

Neural consequences of somatosensory extinction: an fMRI study.

There are currently two main interpretations proposing mechanisms underlying tactile extinction: sensory and attention deficit hypotheses. Kinsbourne proposed an opponent processor model to support the attention deficit hypothesis. He insisted that bilateral hemispheres interact reciprocally through contralaterally oriented vectors, and in patients presenting extinction, balance is impaired, causing inattention. From Kinsbourne's point of view, extinction is not caused by sensory disturbance but inattention, therefore even in extinction patients, simultaneous bilateral stimuli should reach the bilateral primary sensory cortices (SI). Using functional magnetic resonance imaging (fMRI), tactile stimuli were administered to both hands of healthy subjects as well as a tactile extinction patient. The patient with tactile extinction extinguished right palm stimuli following simultaneous palm stimulation. During the fMRI study, we gave tactile stimuli to the right palm, the left palm, and simultaneously to both palms. In normal subjects, simultaneous bilateral stimuli activated the bilateral SI and bilateral secondary sensory cortices (SII). In the patient with right tactile extinction, simultaneous bilateral stimuli activated the bilateral SI along with the bilateral SII and right superior parietal lobule. Our study suggests that activation of SI is insufficient to engender an awareness of sensory stimuli. From the view point of Kinsbourne, stimulus driven activity in one hemisphere suppresses activity in the other hemisphere via callosal connections. Our results support the notion that an undamaged superior parietal lobule in the patient with tactile extinction suppresses the damaged parietal lobe function and causes extinction.

Adolescent↗
PubMed2005

A case of amusia caused by the infarction of anterior portion of bilateral temporal lobes.

It remains an unsettled question which brain regions participate in music perception. During singing a familiar song, the retrieval from long-term memory is necessary, but the mechanism of that retrieval is still unclear. We carried out a detailed examination of musical ability in a patient with amusia and control subjects and identified the lesion sites of our patient using MRI. Compared with controls, the patient manifested the following impairments in music perception: (i) the recognition and discrimination of familiar melodies; (ii) the discrimination of unfamiliar phrases; (iii) the discrimination of isolated chords. During singing familiar nursery songs, the patient showed the replacement of one phrase of the melody. In MRI, the patient had old infarction in the anterior portion of the temporal lobes bilaterally. In conclusion, the anterior temporal lobes participate in the perception and expression of music. During singing, the song is retrieved from long-term memory by a unit of one phrase. The dysfunction of that retrieval caused the replacement of the succeeding phrases of the original with the wrong tune, and we named this phenomenon paramelodia.

Aged↗
PubMed2004

[A case of dementia with motor neuron disease associated with agraphia--the omission of kana letters].

We report a 55-year-old right-handed Japanese man with motor neuron disease and dysgraphia of kana letters. He was admitted to our hospital because of dysarthria and dysphasia. On admission, the results of general physical examination were within normal limits. Neurological examination revealed severe dysarthria, dysphasia, impaired movement of the tongue without fasciculation and slight distal muscle weakness in the bilateral upper limbs. There were no fasciculation of the muscle. Deep tendon reflexes were hyperactive without Babinski's signs. Sensation, coordination, and gait were normal. Neurophysiological studies demonstrated normal motor nerve conduction velocities and sensory action potential. The results of needle electromyography of the upper limbs were compatible with motor neuron disease (MND). Magnetic resonance imaging (MRI) showed atrophy of the bilateral temporal region of the brain. 99mTc-HMPAO SPECT (Single Photon Emission Computed Tomography) showed reduced uptake of tracer in the bilateral temporal region. On neuropsychological examination, his behavior was normal, and orientation and intelligence were also preserved, but his speech was severely impaired. Reading comprehension was slightly impaired. In regard to writing comprehension, he had no difficulty in copying of words though dictation was found to be impaired. He omitted one kana letter in a word. Agraphia is accompanied by various factors such as aphasia, dementia, agnosia, alexia. But in this case at least for early stage, agraphia existed without other higher cortical dysfunction. He did not show severe dementia in his early stage of his disease, but developed it later in the disease's progression. In this case, agraphia might be due to the atrophic changes in the temporal lobe.

Agraphia↗
PubMed2004

[How to examine a patient with higher cortical dysfunction at bedside].

In practice, a neuropsychological evaluation may serve one or more purpose. The first systematic applications of neuropsychological assessment dealt with diagnosis. Before the days of sophisticated neuroimaging, the localization of a cerebral lesion was neuropsychology's most important function. Recent developments in neuroradiological techniques have greatly reduced the contributions of neuropsychological assessment to diagnosis and lesion localization. Today, neuropsychological assessment is most usually called upon for the detailed behavioral description necessary for intelligent patient care, for rational treatment, and for appropriate rehabilitation training. When neurologists examines patients with higher cortical dysfunction, they should bear the following points in mind. At first, good clinical history often holds the key to diagnosis. This is especially true in the neurologic and the neuropsychologic history. The examiners should not hesitate to ask the patient history before and during the neuropsychological examinations. Secondly sometimes the patients with neuropsychological dysfunction do not recognize their disturbances. For example, the patients with apraxia or optic ataxia usually do not complain their disturbances. Only by storing the range of neuropsychological dysfunction in their mind can neurologists recognize these behavioral disturbances. Thirdly in neurology when we localize lesions of the nervous system, it is helpful to think about the major syndrome supervene with lesions at different anatomical levels, from the muscle to the cortex. Also in neuropsychology, for example, when we localize lesions of with speech disturbance it is useful to think about from the simplest level (the muscle) to the cortex. At last test in neuropsychological assessment can be used to establish a comparison standard--i.e. for estimating premorbid ability. The Wechsler test (WAIS-R) is one of the most frequently used measures in neuropsychological batteries. It is a core instrument, giving information about the overall level of intellectual functioning disability, and providing clues to altered functions.

Brain Diseases↗
PubMed2003

The anterior portion of the bilateral temporal lobes participates in music perception: a positron emission tomography study.

BACKGROUND AND PURPOSE: The mechanism underlying the perception of music has been the subject of study for many years. We investigated the role of the anterior portion of the temporal lobes in the perception of music in nonmusicians by use of positron emission tomography (PET). METHODS: We used the subtraction technique for PET to investigate the role of the anterior portion of the bilateral temporal lobes in music perception. Nonmusicians performed two kinds of musical tasks: harmony listening and soprano part listening. RESULTS: During the harmony-listening task, the anterior portion of the temporal lobes, cingulate gyri, and cerebellum were bilaterally activated. During the soprano part-listening task, the bilateral superior parietal lobules, and the right precuneus were significantly activated. CONCLUSION: The anterior portion of the bilateral temporal lobes is vital in the discrimination of melodies and chords. Differences between activated brain regions exist between musicians and nonmusicians when listening to a particular vocal part of a musical phrase.

Adult↗
PubMed2002

Somatosensory and skin temperature disturbances caused by infarction of the postcentral gyrus: a case report.

Somatosensory functions are subdivided into 2 large groups: the elementary somatosensory functions, which consist of light touch, pain, thermal sensation, joint position sense, and vibration sense, and the intermediate somatosensory functions, which include 2-point discrimination, tactile localization, weight, texture, and shape perception. In this report, we describe a patient with somatosensory dysfunction after infarction of the postcentral gyrus. On physical examination a month after the onset of the infarction, voluntary movements were skillful, and both the elementary and intermediate somatosensory functions were disturbed in the right hand. The patient also displayed a decrease in the skin temperature of the right hand. The sensory-evoked potential in response to electrical stimulation of the right median nerve was normal, and brain MRI showed that the infarction was located in the posterior half of the left postcentral gyrus. These findings suggested that the lesion was situated at areas 1 and 2, and that area 3b was preserved. Thermography revealed that the skin temperature of the right hand was decreased predominantly on the ulnar side, and that recovery from cooling with ice water was delayed. By comparing the results of our patient with a case report that showed no disturbance of the elementary somatosensory functions with a localized lesion in the postcentral gyrus, we suggest that area 1 participates in the elementary somatosensory functions and that skin temperature may be controlled somatotopically in the somatosensory cortex.

Cerebral Infarction↗