T Hanakawa

Publications (30)187.25 Total impact

• Article: Hemispheric asymmetry of the arcuate fasciculus

  R. Matsumoto, T. Okada, N. Mikuni, T. Mitsueda-Ono, J. Taki, N. Sawamoto, T. Hanakawa, Y. Miki, N. Hashimoto, H. Fukuyama, R. Takahashi, A. Ikeda
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  ABSTRACT: Objective Lateralization of language function is a prominent feature of human brain function, and its underlying structural asymmetry has been recently reported in normal right-handed subjects. By means of diffusion tensor tractography (DTT), we investigated the asymmetry of the language network, namely, the arcuate fasciculus in patients in whom the unilateral language dominance was defined by Wada test. Methods DTT was performed in 24 patients with a focal lesion or an epileptic focus outside the C-shaped segment of the arcuate fasciculus. The arcuate fasciculus was reconstructed by placing two regions-of-interest in the deep white matter lateral to the corona radiata. The pathway was then divided into one terminating in the temporal lobe (FT tract) and the other in the parietal lobe (FP tract). The relative number and volume of the FT and FP tracts in each hemisphere were submitted to repeated measure ANOVA separately, with the hemisphere as a within-subject factor and with the side of pathology as a betweensubject factor. Results The FT tract showed a significantly larger number and volume in the language dominant hemisphere than in the non-dominant hemisphere, while, for the FP tract, no significant hemispheric difference was observed in the relative number or volume. There was a tendency that the FT tract was less lateralized when the pathology was located in the dominant hemisphere than in the non-dominant hemisphere. Conclusion Dominance of the FT tract in the language dominant hemisphere was demonstrated for the first time in a patient population and implicated a clinical utility of DTT for non-invasive evaluation of language lateralization. Our preliminary study might indicate reorganization of the language network in conjunction with pathology.
  Journal of Neurology 04/2012; 255(11):1703-1711. · 3.47 Impact Factor
• Article: Hemispheric asymmetry of the arcuate fasciculus: a preliminary diffusion tensor tractography study in patients with unilateral language dominance defined by Wada test.

  R Matsumoto, T Okada, N Mikuni, T Mitsueda-Ono, J Taki, N Sawamoto, T Hanakawa, Y Miki, N Hashimoto, H Fukuyama, R Takahashi, A Ikeda
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  ABSTRACT: Lateralization of language function is a prominent feature of human brain function, and its underlying structural asymmetry has been recently reported in normal right-handed subjects. By means of diffusion tensor tractography (DTT), we investigated the asymmetry of the language network, namely, the arcuate fasciculus in patients in whom the unilateral language dominance was defined by Wada test. DTT was performed in 24 patients with a focal lesion or an epileptic focus outside the C-shaped segment of the arcuate fasciculus. The arcuate fasciculus was reconstructed by placing two regions-of-interest in the deep white matter lateral to the corona radiata. The pathway was then divided into one terminating in the temporal lobe (FT tract) and the other in the parietal lobe (FP tract). The relative number and volume of the FT and FP tracts in each hemisphere were submitted to repeated measure ANOVA separately, with the hemisphere as a within-subject factor and with the side of pathology as a between subject factor. The FT tract showed a significantly larger number and volume in the language dominant hemisphere than in the non-dominant hemisphere, while, for the FP tract, no significant hemispheric difference was observed in the relative number or volume. There was a tendency that the FT tract was less lateralized when the pathology was located in the dominant hemisphere than in the non-dominant hemisphere. Dominance of the FT tract in the language dominant hemisphere was demonstrated for the first time in a patient population and implicated a clinical utility of DTT for non-invasive evaluation of language lateralization. Our preliminary study might indicate reorganization of the language network in conjunction with pathology.
  Journal of Neurology 10/2008; 255(11):1703-11. · 3.47 Impact Factor
• Article: Cognitive slowing in Parkinson disease is accompanied by hypofunctioning of the striatum.

  N Sawamoto, M Honda, T Hanakawa, T Aso, M Inoue, H Toyoda, K Ishizu, H Fukuyama, H Shibasaki
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  ABSTRACT: To investigate whether cognitive slowing in Parkinson disease (PD) reflects disruption of the basal ganglia or dysfunction of the frontal lobe by excluding an influence of abnormal brain activity due to motor deficits. We measured neuronal activity during a verbal mental-operation task with H(2)(15)O PET. This task enabled us to evaluate brain activity change associated with an increase in the cognitive speed without an influence on motor deficits. As the speed of the verbal mental-operation task increased, healthy controls exhibited proportional increase in activities in the anterior striatum and medial premotor cortex, suggesting the involvement of the corticobasal ganglia circuit in normal performance of the task. By contrast, patients with PD lacked an increase in the striatal activity, whereas the medial premotor cortex showed a proportional increase. Although the present study chose a liberal threshold and needs subsequent confirmation, the findings suggest that striatal disruption resulting in abnormal processing in the corticobasal ganglia circuit may contribute to cognitive slowing in Parkinson disease, as is the case in motor slowing.
  Neurology 04/2007; 68(13):1062-8. · 8.31 Impact Factor
• Article: Diffusion tensor fiber tractography of the optic radiation: analysis with 6-, 12-, 40-, and 81-directional motion-probing gradients, a preliminary study.

  A Yamamoto, Y Miki, S Urayama, Y Fushimi, T Okada, T Hanakawa, H Fukuyama, K Togashi
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  ABSTRACT: Knowing the exact location of the optic radiation preoperatively is important for surgery of the temporal lobe. We hypothesized that a greater number of motion-probing gradients (MPGs) would provide better results of diffusion tensor (DT) fiber tractography of the optic radiation. To test this hypothesis, this study evaluated differences in DT fiber tractography of the optic radiation under different MPG settings. DT images were obtained in 12 healthy volunteers (7 men, 5 women) with a mean age of 32 years (range, 22-45 years) by using a 3T MR imaging scanner with single-shot echo-planar imaging with parallel acquisition (reduction factor = 2). MPG was applied in 6, 12, 40, and 81 independent directions. The first region of interest (ROI) was placed in the occipital lobe, and the second ROI was placed in the lateral geniculate body. Fibers penetrating both ROIs were considered as the optic radiation. Anteroposterior distance between the tip of the Meyer loop and the lateral geniculate body on an axial section was defined as a loop index. Numbers of fibers and loop indices in both cerebral hemispheres were evaluated statistically. The optic radiation was well visualized in full length by DT fiber tractography in 20 of 24 hemispheres (83%). No significant differences were noted in number of fibers and loop indices among different MPG settings. DT fiber tractography can frequently depict almost the entire optic radiation. MPG number does not exert any significant effect on visualization of the optic radiation, and 6-directional MPG is thus sufficient for this purpose.
  American Journal of Neuroradiology 02/2007; 28(1):92-6. · 2.93 Impact Factor
• Source

  Available from: kyoto-u.ac.jp

  Article: Prefrontal hypofunction in patients with intractable mesial temporal lobe epilepsy.

  S Takaya, T Hanakawa, K Hashikawa, A Ikeda, N Sawamoto, T Nagamine, K Ishizu, H Fukuyama
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  ABSTRACT: We compared the cognitive functions and interictal cerebral glucose metabolism of 11 patients with mesial temporal lobe epilepsy (MTLE) with frequent seizures to those of 10 patients with MTLE with rare seizures; the groups were matched for age, sex, education, IQ, and focus side. The frequent-seizure group had more set-shifting impairment that correlated with glucose hypometabolism in the prefrontal cortices. Our results suggest that frequent seizures in MTLE are associated with hypofunction of the prefrontal cortex.
  Neurology 12/2006; 67(9):1674-6. · 8.31 Impact Factor
• Source

  Available from: J. Crinion

  Article: Language control in the bilingual brain.

  J Crinion, R Turner, A Grogan, T Hanakawa, U Noppeney, J T Devlin, T Aso, S Urayama, H Fukuyama, K Stockton, K Usui, D W Green, C J Price
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  ABSTRACT: How does the bilingual brain distinguish and control which language is in use? Previous functional imaging experiments have not been able to answer this question because proficient bilinguals activate the same brain regions irrespective of the language being tested. Here, we reveal that neuronal responses within the left caudate are sensitive to changes in the language or the meaning of words. By demonstrating this effect in populations of German-English and Japanese-English bilinguals, we suggest that the left caudate plays a universal role in monitoring and controlling the language in use.
  Science 07/2006; 312(5779):1537-40. · 31.20 Impact Factor
• Article: Ictal monoparesis associated with lesions in the primary somatosensory area.

  R Matsumoto, A Ikeda, T Hitomi, T Aoki, T Hanakawa, Y Miki, H Tomimoto, S Shimohama, H Shibasaki
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  ABSTRACT: Reported are three patients with ictal monoparesis of an arm. In the hemisphere contralateral to the monoparesis, ictal and interictal epileptiform discharges were observed in the centroparietal area, and a well-circumscribed lesion was commonly present in the primary arm somatosensory area (SI). In the presence of an SI lesion, the epileptic activity at the sensorimotor area could lead to selective or predominant activation of the inhibitory motor system.
  Neurology 12/2005; 65(9):1476-8. · 8.31 Impact Factor
• Article: Neural mechanisms underlying the processing of Chinese words: an fMRI study.

  Y Dong, K Nakamura, T Okada, T Hanakawa, H Fukuyama, J C Mazziotta, H Shibasaki
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  ABSTRACT: The present study employed functional magnetic resonance imaging (fMRI) to investigate the neural mechanisms underlying orthographic, phonological and semantic processing of single character Chinese words. Twelve right-handed native Chinese speakers participated in the study. Three fundamental linguistic tasks including orthographic judgment, phonological matching and semantic association task were used. Our results demonstrated robust activation in the left posterior inferior temporal cortex (BA 37) for all three tasks. While the phonological matching task produced left-lateralized activation in the inferior frontal and parietal regions, semantic association task showed considerable bilateral activation in the inferior frontal and occipito-parietal regions. Direct comparison between phonological matching and semantic association task yielded semantic related activation in the anterior portion of the left inferior frontal gyrus (BA 47) and the right inferior frontal region (Broca's homology; BA 45). Behaviorally, there was no difference in response time between phonological matching and semantic association task. Our findings suggested that differential neural pathways were involved in the processing of meaning and sound of single-character Chinese words. The present study provided systemic information of the neural substrates underlying the processing of different components of Chinese language.
  Neuroscience Research 07/2005; 52(2):139-45. · 2.25 Impact Factor
• Article: Abnormal cortical mechanisms of voluntary muscle relaxation in patients with writer's cramp: an fMRI study.

  T Oga, M Honda, K Toma, N Murase, T Okada, T Hanakawa, N Sawamoto, T Nagamine, J Konishi, H Fukuyama, R Kaji, H Shibasaki
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  ABSTRACT: Although it is hypothesized that there is abnormal motor inhibition in patients with dystonia, the question remains as to whether the mechanism related to motor inhibition is specifically impaired. The objective of the present study was to clarify the possible abnormalities of the mechanisms underlying voluntary muscle relaxation during motor preparation and execution in patients with writer's cramp, using event-related functional MRI. Eight patients with writer's cramp and 12 age-matched control subjects participated in the study. Two motor tasks were employed as an experimental paradigm. In the relaxation task, subjects were asked to hold their right wrist in the horizontal plane by maintaining moderate contraction of wrist extensor muscles in the premotor phase; they relaxed those muscles voluntarily just once during each fMRI scanning session. In the contraction task, subjects extended the right wrist voluntarily from the same premotor state as for the relaxation task. Five axial images covering the primary sensorimotor cortex (SMC) and supplementary motor area (SMA) were obtained once every second. Activated volumes in the left SMC and the SMA were significantly reduced in patients for both muscle relaxation and contraction tasks. These data suggest that there is impaired activation in both SMC and SMA in voluntary muscle relaxation and contraction in patients with writer's cramp. This implies that abnormalities of both inhibitory and excitatory mechanisms in motor cortices might play a role in the pathophysiology of focal dystonia.
  Brain 05/2002; 125(Pt 4):895-903. · 9.46 Impact Factor
• Article: Functional mapping of human medial frontal motor areas. The combined use of functional magnetic resonance imaging and cortical stimulation.

  T Hanakawa, A Ikeda, N Sadato, T Okada, H Fukuyama, T Nagamine, M Honda, N Sawamoto, S Yazawa, T Kunieda, S Ohara, W Taki, N Hashimoto, Y Yonekura, J Konishi, H Shibasaki
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  ABSTRACT: Two functional brain-mapping techniques, functional magnetic resonance imaging (fMRI) and cortical stimulation by chronically implanted subdural electrodes, were used in combination for presurgical evaluation of three patients with intractable, partial motor seizures. Brain mapping was focused on characterizing motor-related areas in the medial frontal cortex, where all patients had organic lesions. Behavioral tasks for fMRI involved simple finger and foot movements in all patients and mental calculations in one of them. These tasks allowed us to discriminate several medial frontal motor areas: the presupplementary motor areas (pre-SMA), the somatotopically organized SMA proper, and the foot representation of the primary motor cortex. All patients subsequently underwent cortical stimulation through subdural electrodes placed onto the medial hemispheric wall. In each patient, the cortical stimulation map was mostly consistent with that patient's brain map by fMRI. By integrating different lines of information, the combined fMRI and cortical stimulation map will contribute not only to safe and effective surgery but also to further understanding of human functional neuroanatomy.
  Experimental Brain Research 07/2001; 138(4):403-9. · 2.39 Impact Factor
• Article: Carotid brainstem reflex myoclonus after hypoxic brain damage.

  T Hanakawa, S Hashimoto, K Iga, Y Segawa, H Shibasaki
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  ABSTRACT: A patient comatose after acute anoxia developed bilaterally synchronous, periodic myoclonic jerks most prominently in the bilateral upper limbs. Although the myoclonus seemed to occur spontaneously, electrophysiological studies showed that the myoclonic jerks correlated in timing and size with arterial pulses, and was suppressed by massage over the carotid sinus. It is proposed that the present myoclonus is a variant of brainstem reflex myoclonus in which arterial pulses served as intrinsic trigger stimuli via the carotid sinus and the medullary reticular formation.
  Journal of Neurology Neurosurgery &amp Psychiatry 12/2000; 69(5):672-4. · 4.76 Impact Factor
• Article: Expectation of pain enhances responses to nonpainful somatosensory stimulation in the anterior cingulate cortex and parietal operculum/posterior insula: an event-related functional magnetic resonance imaging study.

  N Sawamoto, M Honda, T Okada, T Hanakawa, M Kanda, H Fukuyama, J Konishi, H Shibasaki
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  ABSTRACT: Although behavioral studies suggest that pain distress may alter the perception of somatic stimulation, neural correlates underlying such alteration remain to be clarified. The present study was aimed to test the hypothesis that expectation of pain might amplify brain responses to somatosensory stimulation in the anterior cingulate cortex (ACC) and the region including parietal operculum and posterior insula (PO/PI), both of which may play roles in regulating pain-dependent behavior. We compared brain responses with and subjective evaluation of physically identical nonpainful warm stimuli between two psychologically different contexts: one linked with pain expectation by presenting the nonpainful stimuli randomly intermixed with painful stimuli and the other without. By applying the event-related functional magnetic resonance imaging technique, brain responses to the stimuli were assessed with respect to signal changes and activated volume, setting regions of interest on activated clusters in ACC and bilateral PO/PI defined by painful stimuli. As a result, the uncertain expectation of painful stimulus enhanced transient brain responses to nonpainful stimulus in ACC and PO/PI. The enhanced responses were revealed as a higher intensity of signal change in ACC and larger volume of activated voxels in PO/PI. Behavioral measurements demonstrated that expectation of painful stimulus amplified perceived unpleasantness of innocuous stimulus. From these findings, it is suggested that ACC and PO/PI are involved in modulation of affective aspect of sensory perception by the uncertain expectation of painful stimulus.
  Journal of Neuroscience 11/2000; 20(19):7438-45. · 7.11 Impact Factor
• Article: Participation of the left posterior inferior temporal cortex in writing and mental recall of kanji orthography: A functional MRI study.

  K Nakamura, M Honda, T Okada, T Hanakawa, K Toma, H Fukuyama, J Konishi, H Shibasaki
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  ABSTRACT: To examine the neuropsychological mechanisms involved in writing kanji (morphograms), we used functional MRI (fMRI) in 10 normal volunteers, all right-handed, native Japanese speakers. The experimental paradigms consisted of kana-to-kanji transcription, mental recall of kanji orthography and oral reading and semantic judgement of kana words. The first two tasks require manual and mental transcription of visually presented kana words into kanji, respectively, whereas the last two tasks involve language processing of the same set of stimulus words without recall of kanji. The transcription and mental recall tasks yielded lateralized activation of the left posterior inferior temporal cortex (PITC). By contrast, neither oral reading nor semantic judgement produced similar activation of the area. These results, in good accordance with lesion data, provide converging evidence that the left PITC plays an important role in writing kanji through retrieval of their visual graphic images, and suggest language-specific cerebral organization of writing. The set of fMRI experiments also provides new neuroimaging data on the cortical localization of basic language functions in people using a non-alphabetical language.
  Brain 06/2000; 123 ( Pt 5):954-67. · 9.46 Impact Factor
• Article: Essential role of the right superior parietal cortex in Japanese kana mirror reading: An fMRI study.

  Y Dong, H Fukuyama, M Honda, T Okada, T Hanakawa, K Nakamura, Y Nagahama, T Nagamine, J Konishi, H Shibasaki
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  ABSTRACT: Functional magnetic resonance imaging (fMRI) was used to investigate the neural substrates responsible for Japanese kana mirror reading. Japanese kana words, arranged vertically from top to bottom, were used in the mirror reading task in 10 normal right-handed Japanese adults. Since both mirror-reversed and normally oriented kana items are read in the same (top to bottom) direction, it was possible to minimize the oculomotor effects which often occur in the process of mirror reading of alphabetical language. By using the SPM96 random effect analysis method, a significant increase in the blood oxygen level-dependent signal during mirror reading relative to normal reading was detected in multiple brain regions, including the bilateral superior occipital gyri, bilateral middle occipital gyri corresponding to Brodmann area (BA) 18/19, bilateral lingual gyri (BA 19), left inferior occipital gyrus (BA 18), left inferior temporal cortex (BA 37), bilateral fusiform gyri (BA 19), right superior parietal cortex (SPC) (BA 7), left inferior frontal gyrus (BA 44/45) and an inferior part of the left BA 6. In addition to these cortical regions, the right caudate nucleus and right cerebellum were also activated. The activation found in the right SPC and the left inferior temporal region is consistent with the hypothesis that mirror reading involves both the dorsal visuospatial and ventral object recognition pathways. In particular, a significant correlation was found between the fMRI signal change in the right SPC and the behavioural performance (error index) in the task. This may reflect increased demand on the right SPC for the spatial transformation which is required for the accurate recognition of mirror-reversed kana items. This relationship between the haemodynamic response in a specific brain area and the behavioural data provides new evidence for the essential role of the right SPC in Japanese kana mirror reading.
  Brain 05/2000; 123 ( Pt 4):790-9. · 9.46 Impact Factor
• Article: Brain structures related to active and passive finger movements in man.

  T Mima, N Sadato, S Yazawa, T Hanakawa, H Fukuyama, Y Yonekura, H Shibasaki
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  ABSTRACT: A PET study was performed in six normal volunteers to elucidate the functional localization of the sensory afferent component during finger movement. Brain activation during the passive movement driven by a servo-motor was compared with that during an auditory-cued active movement which was controlled kinematically in the same way as the passive one. A newly developed device was used for selectively activating proprioception with a minimal contribution from tactile senses. Active movement was associated with activation of multiple areas, including the contralateral primary sensorimotor cortex, premotor cortex, supplementary motor area (SMA), bilateral secondary somatosensory areas and basal ganglia and ipsilateral cerebellum. In contrast, only the contralateral primary and secondary somatosensory areas were activated by the passive movement. It is likely that the contribution of proprioceptive input to the activation of the premotor cortex, SMA, cerebellum and basal ganglia, if any, is small. However, the present results do not rule out the possibility that the cutaneous afferent input or the combination of cutaneous and proprioceptive input participates in the activation of those areas during the active movement.
  Brain 11/1999; 122 ( Pt 10):1989-97. · 9.46 Impact Factor
• Article: Transient neural activity in the medial superior frontal gyrus and precuneus time locked with attention shift between object features.

  Y Nagahama, T Okada, Y Katsumi, T Hayashi, H Yamauchi, N Sawamoto, K Toma, K Nakamura, T Hanakawa, J Konishi, H Fukuyama, H Shibasaki
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  ABSTRACT: To investigate the contribution of the superior frontal gyrus and precuneus to the cognitive process of attention set shift, we examined the correlation between change in neural activity in these areas and the timing of attention set shift using event-related functional magnetic resonance imaging. Seven subjects underwent a card-sorting task in which they matched a test card to one of two target cards according to color or shape. The subjects had to determine the correct category based only on feedback and shift the sorting principle when the feedback changed from "correct" to "incorrect." Transient increase of neural activity time locked with attention shift phases was detected in the medial superior frontal gyrus (the rostral part of the supplementary motor area) and precuneus. During the control task, in which the feedback and the motor responses were preserved without any attention shift, this type of change in neural activity was not observed. Our findings indicate that increase in neural activity in these brain areas may be closely related to attention set shift between object features and suggest that these areas may play a role in the shifting of cognitive sets.
  NeuroImage 09/1999; 10(2):193-9. · 5.89 Impact Factor
• Article: The effect of sequential lesioning in the basal forebrain on cerebral cortical glucose metabolism in rats. An animal positron emission tomography study.

  Y Katsumi, T Hanakawa, H Fukuyama, T Hayashi, Y Nagahama, H Yamauchi, Y Ouchi, H Tsukada, H Shibasaki
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  ABSTRACT: We studied the effect of the cortical projection from the basal forebrain on the cerebral cortical metabolism using positron emission tomography (PET) with [(18)F] fluorodeoxyglucose. Unilateral damage of the nucleus basalis magnocellularis (NBM) did not cause a permanent reduction of cortical metabolism: recovery was observed 4 weeks after the operation. Destruction of the contralateral side after recovery from unilateral damage produced persistent bilateral suppression of glucose metabolism, with partial recovery. We speculate that recovery from the unilateral NBM lesions is partly ascribable to the cholinergic projection from the contralateral NBM, and partly due to non-cholinergic systems, and conclude that bilateral damage might be responsible for persistent cortical glucose metabolism suppression.
  Brain Research 09/1999; 837(1-2):75-82. · 2.73 Impact Factor
• Article: Cerebral glucose metabolism in unilateral entorhinal cortex-lesioned rats: an animal PET study.

  T Hayashi, H Fukuyama, Y Katsumi, T Hanakawa, Y Nagahama, H Yamauchi, H Tsukada, H Shibasaki
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  ABSTRACT: To evaluate the effect of entorhinal cortical lesion on cerebral cortical function, we studied cerebral glucose utilization (CMRGlc) using a high resolution PET scanner after quinolinic acid lesion of the unilateral entorhinal cortex in rats. [18F]Fluorodeoxyglucose PET was performed at 4 days and 4 weeks after surgery, and CMRGlc in the bilateral frontal, parietal and temporal regions were analyzed. At 4 days, the entorhinal lesion induced a 12-15% decrease in CMRGlc of frontal, parietal and temporal regions ipsilateral to the lesion. The hypometabolism continued at 4 weeks in the temporal region. These findings suggest that entorhinal lesion induces cerebral cortical hypometabolism, which implies a pathogenetic role of entorhinal area on the cortical hypometabolism in Alzheimer's disease.
  Neuroreport 08/1999; 10(10):2113-8. · 1.66 Impact Factor
• Article: Mechanisms underlying gait disturbance in Parkinson's disease: a single photon emission computed tomography study.

  T Hanakawa, Y Katsumi, H Fukuyama, M Honda, T Hayashi, J Kimura, H Shibasaki
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  ABSTRACT: Single photon emission computed tomography was used to evaluate regional cerebral blood flow changes during gait on a treadmill in 10 patients with Parkinson's disease and 10 age-matched controls. The subjects were injected with [99mTc]hexamethyl-propyleneamine oxime twice: while walking on the treadmill, which moved at a steady speed, and while lying on a bed with their eyes open. On the treadmill, all subjects walked at the same speed with their preferred stride length. The patients showed typical hypokinetic gait with higher cadence and smaller stride length than the controls. In the controls, a gait-induced increase in brain activity was observed in the medial and lateral premotor areas, primary sensorimotor areas, anterior cingulate contex, superior parietal cortex, visual cortex, dorsal brainstem, basal ganglia and cerebellum. The Parkinson's disease patients revealed relative underactivation in the left medial frontal area, right precuneus and left cerebellar hemisphere, whereas they showed relative overactivity in the left temporal cortex, right insula, left cingulate cortex and cerebellar vermis. This is the first experimental study showing that the dorsal brainstem, which corresponds to the brainstem locomotor region in experimental animals, is active during human bipedal gait. The reduced brain activity in the medial frontal motor areas is a basic abnormality in motor performance in Parkinson's disease. The underactivity in the left cerebellar hemisphere, in contrast to the overactivity in the vermis, could be associated with a loss of lateral gravity shift in parkinsonian gait.
  Brain 08/1999; 122 ( Pt 7):1271-82. · 9.46 Impact Factor
• Article: Activities of the primary and supplementary motor areas increase in preparation and execution of voluntary muscle relaxation: an event-related fMRI study.

  K Toma, M Honda, T Hanakawa, T Okada, H Fukuyama, A Ikeda, S Nishizawa, J Konishi, H Shibasaki
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  ABSTRACT: Brain activity associated with voluntary muscle relaxation was examined by applying event-related functional magnetic resonance imaging (fMRI) technique, which enables us to observe change of fMRI signals associated with a single motor trial. The subject voluntarily relaxed or contracted the right upper limb muscles. Each motor mode had two conditions; one required joint movement, and the other did not. Five axial images covering the primary motor area (M1) and supplementary motor area (SMA) were obtained once every second, using an echoplanar 1.5 tesla MRI scanner. One session consisted of 60 dynamic scans (i.e., 60 sec). The subject performed a single motor trial (i.e., relaxation or contraction) during one session in his own time. Ten sessions were done for each task. During fMRI scanning, electromyogram (EMG) was monitored from the right forearm muscles to identify the motor onset. We calculated the correlation between the obtained fMRI signal and the expected hemodynamic response. The muscle relaxation showed transient signal increase time-locked to the EMG offset in the M1 contralateral to the movement and bilateral SMAs, where activation was observed also in the muscle contraction. Activated volume in both the rostral and caudal parts of SMA was significantly larger for the muscle relaxation than for the muscle contraction (p < 0.05). The results suggest that voluntary muscle relaxation occurs as a consequence of excitation of corticospinal projection neurons or intracortical inhibitory interneurons, or both, in the M1 and SMA, and both pre-SMA and SMA proper play an important role in motor inhibition.
  Journal of Neuroscience 05/1999; 19(9):3527-34. · 7.11 Impact Factor