The visual acuity of human eye is not uniform over the retina, but is almost only good at a narrow central portion called the fovea. This forces the eyes to move around to acquire the information of the outside world. Indeed the eyes move very rapidly and continuously so that the fovea covers the entire field of the outside. We may ask then that a wide visual field may be unnecessary to perceive figures and to read letters as long as the eyes can use the fovea and can move at will. An artificially limited visual field was imposed to a subject while he/she reads sentences or looks at a figure. It was found that if the field became too narrow the pattern recognition became impossible to imply that a certain size of the visual field is indeed needed for the eyes to carry out their task of pattern perception. The difference between the outside world and the retinal image was also discussed, the former being 3D while the latter 2D. The brain has to recover the dimensionality to perceive the outside world rightly. It was pointed out that we experience the recovery in the phenomenon called size constancy.

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    We reported 7 patients who exhibited imitation behavior following damage to the medial frontal lobe. On the basis of symptomatological features of imitation behavior, the patients were divided into 2 groups (A and B). In group A (4 patients), imitation behavior appeared in both upper extremities and other body parts. It showed no signs of inhibition and seemed to be related to the patient's own will. In group B (3 patients), on the other hand, imitation behavior appeared only in the right upper extremity in response to visual stimulus and was inhibited by the left hand. It seemed to be a kind of compulsive behavior against the patient's will. In group A, when generalized attention was reduced, the category of stimuli which induce imitation behavior, body parts involved and patterns of behavior tended to become more extensive and varying. The lesions of group A were located in the middle and posterior parts of the anterior cingulate gyrus, whereas in group B the lesions in the anterior part of the anterior cingulate gyrus seemed to be important in inducing imitation behavior. The anterior cingulate gyrus seems to control the activities of the parietal lobe and premotor cortex in response to sensory stimuli. Results further suggested that there are differences in function between the anterior part of the anterior cingulate gyrus, and its middle and posterior parts.

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    We performed intracarotid amobarbital tests on 430 patients who were being evaluated for epilepsy surgery in our hospital. There were 46 patients who had right hemisphere language dominance. The side of epileptogenic focus, handedness, family history of sinistrality, etiology of epilepsy, and performance of neuropsychological testing were examined. Twenty-seven patients had left-sided epileptogenic focus, 14 had right-sided focus and 5 had bilateral or undetermined side of epileptogenicity. Twenty-four patients were dextral, 22 patients were ambidextral or sinistral. There were 17 patients who had family members with sinistrality. The occurrence of right hemisphere language dominance was not correlated with a family history of sinistrality. Among the patients who underwent surgery and were histopathologically examined, all had evidence of brain damage or congenital abnormality. The right language dominance may result from a secondary shifting from left to right hemisphere. Neuropsychological testing revealed that the performance of tests of memory and verbal function in patients with left epileptogenic focus was lower than that of patients with right epileptogenic focus. Brain damage that inevitably resulted in a right language dominance may be more serious in patients with left epileptogenic focus than those with right epileptogenic focus.

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    The Ishikawa Prefecture Aphasia Circle was established in 1976. On the 20th anniversary of this group, the members and their families were interviewed by speech therapists. The results were as follows : More than 90% of the patients suffered aphasia following a stroke. By type, 47% had motor aphasia, 14.8% sensory aphasia, and 11.3% global aphasia. Language impairment was as follows : severe, 28.0% ; moderate, 39.0% ; mild, 33.0%. Aphasic patients who were affected between the ages of 50 and 70 made up 83.3%. Only 9.4% of the patients held occupations after rehabilitation. These results were simular to statistics reported by the Japanese College of Aphasiology.

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    We report a phonological dyslexic patient, HN, and discuss his reading process of kana words and nonwords. He has been suffering from amnestic aphasia after a cerebral infarction on his left hemisphere. In our experimental investigations, it was observed that he read aloud real kana words and single kana characters quite well, while he often made a mistake in reading kana nonwords especially ones that look like real words. Also he had some difficulties with phonological manipulation tasks. Although he produced a lot of semantic errors on the reading aloud real kanji words early in the convalescent period, such paralexia has dramatically decreased. This fact suggests that he is now a phonological dyslexic who has recovered from deep dyslexic syndrome.
    Based on the traditional dual-route reading theory, it is suggested that the impairment of the reading aloud kana nonwords is caused by the dysfunction of the grapheme-phoneme conversion (GPC), however we think that HN has no problem with his GPC system because he can read single kana characters and pseudowords well. Further HN never reads a kana nonword letter by letter, but reads it as a whole like a real word. Therefore to analyze the dyslexic symptom of this case, we adopt the so-called “triangle model” (Patterson et al., 1996 ; Sasanuma et al., 1996) which shows a single direct reading route without the GPC route.

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    We studied color naming and reading of the unilateral visual field by tachystoscope, and dichotic listening of a case with a tumor lesion in the splenium of the corpus callosum. The patient, a 68-year-old, right-handed female, was admitted to Ushioda General Hospital for acute amnesic syndrome. Magnetic resonance imaging showed a tumorous lesion from the splenium of the corpus callosum to the right forceps major and in the left fornix. Stereotactic biopsy revealed this lesion to be glioblastoma multiforme. Tachystoscopic findings showed color naming disturbance and alexia of the left visual field. Dichotic listening resulted in left ear extinction. The patient exhibited neither apraxia nor agraphia, and she had normal tactile naming of the left hand and no crossed optic ataxia. Since there are few studies on color naming disturbance of the left visual field caused by corpus callosum lesion, its mechanism is unclear. However, this case's lesion extends from the commissural fibers through the splenium of the corpus callosum. Findings suggest that the fibers associated with color naming run through the splenium of the corpus callosum and that these fibers are near the fibers associated with reading and auditory language recognition.

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    The aim of this experiment was to investigate the effects of speech on the excitability of corticospinal pathways to human hand muscles. Single transcranial magnetic stimuli were given randomly over the hand area of either the left or right motor cortex of 10 right-handed normal volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects a : read aloud a piece of text, b : read silently, c : spoke spontaneously, or d : made sounds without speaking. The only consistent effect across subjects occurred during task a, which significantly increased the size of responses evoked in the dominant hand of all subjects, but had either no effect (8 subjects) or a smaller effect in the nondominant hand. Tasks b and d had no reliable effect, whereas task c tended to increase response size in both hands. Control measurements suggest that the effects in task a were caused by changes in cortical rather than spinal excitability. This is the first demonstration of lateralized speech effects on the excitability of cortical arm areas. We assume that the results provide a useful adjunct to other tests for determination of cerebral dominance, using only single-rather repetitive-pulse cortical stimulation.

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    This study reports the rehabilitation process of a mild pure alexic patient. The patient, a 28-year-old right-handed Japanese man with a college education, developed right homonymous hemianopsia and pure alexia following an excision of an arteriovenous malformation in the left occipital lobe. After we gave him repetitive practices with flash-cards designed to prompt whole-word reading, the speed of reading 2-or 3-kana character words increased, and the increased speed generalized to untrained words. As regard to 4-or 5-kana character words, however, the speed of reading the trained words increased but the generalization did not occur. Then, we introduced to him the multiple oral rereading (MOR) technique, and the speed of reading paragraphs continued to increase thereafter. These results suggest that the modified flash-cards therapy enabled the patient to acquire speedy reading of 2-or 3-kana character words, but that so-called “word-length effect” might persist despite of the therapy. It is possible that the ability to read rapidly 2-or 3-kana character words might contribute improvement of the overall speed of reading Japanese kanji and kana mixed paragraphs. The implication of these observations for the mechanism of recovery process of pure alexia is discussed.

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    The case of a left-temporally damaged patient with impairment of verbal memory span is reported. The patient was a 21-year-old right-handed female. On admission, she was alert and oriented to all spheres. She spoke fluently without paraphasia, and her naming, comprehension, writing and reading abilities were excellent. Her language performance showed no signs of aphasia. She exhibited neither apraxia nor agnosia, and her intellectual abilities were well preserved.
    One striking finding was that her digit span score was four. Her sentence repeating ability was preserved but repetition of nonsense syllables was profoundly disturbed. Further neuropsychological study revealed dissociations between short-term and long-term verbal memory, and between verbal and non-verbal short-term memory. Both dissociations may be attributed to a selective deficit in verbal short-term memory.
    In parallel, we also present the case of a patient who developed conduction aphasia at the time of onset but who thereafter had only minimal aphasia although disturbances of digit span and repeating ability remained. We then compare these cases with previously reported cases of selective impairment of short-term memory.
    Among these cases, we found differences in repeating and comprehension abilities. The above-mentioned findings suggest that these differences derive from aphasia. We further discuss the purity of impairment of verbal short-term memory.

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