武田 湖太郎

During mental rotation tasks using hand pictures, right-handers make left-right judgements by mentally rotating their own hand to an orientation of the presented hand image. Although strategy difference for the tasks between left- and right-handers has been suggested, the strategy of left-handers has been incompletely understood. In the present study we compared differences in reaction times between 15 left-handed and 16 right-handed normal individuals during a mental rotation task using simple hand pictures. Participants were required to identify pictures of a hand presented in four orientations (upright, counterclockwise rotated, clockwise rotated, and inverted) as either a right or a left hand. Right-handers recognised a right hand faster than a left hand, whereas no significant difference was seen for left-handers. Both left- and right-handers recognised a right hand faster than a left hand in counterclockwise-rotated images, and recognised a left hand faster than a right hand in clockwise-rotated images. The findings suggest that the differences in the reaction times between left- and right-handers depend on a laterality balance of hand motor skills. During mental rotation task using simple hand pictures, left-handers may mentally simulate their own hand to match the stimulus image as similar to right-handers.

WMFTはCI療法の治療効果判定を目的に開発された上肢運動機能評価である。今回WMFT運動課題の中から難易度の異なる3課題"Hand to table"、"Lift can"、"Lift pencil"を選択し課題施行中の運動学的解析を行うとともに、大脳皮質血中ヘモグロビン濃度長の変化について近赤外線分光法を用いて測定した。対象は健常成人13名とし、課題間の一次感覚運動野および補足運動野の活性化を比較した。結果"Lift pencil"においては"Hand to table"に比べて総軌跡長、ピーク速度、躍度が、また"Lift can"に比べてピーク速度、躍度が有意に低下し、補足運動野の皮質血流は"Lift pencil"が"Hand to table"よりも有意に増加することが観察された。本研究によりWMFT運動課題と皮質血流との関連が初めて示され、特に本研究で検討した3課題においては補足運動野の活動との関連が示唆された。(著者抄録)

手工芸活動は統合失調症患者を対象とした作業療法で用いられている。手工芸の教授方法の違いによる脳活動の違いを明らかにするため、近赤外分光法を用いて麻紐編みの編み方思考時の脳活動を計測した。健常成人8名を対象とし、麻紐の完成見本のみを提示した試行錯誤課題と、編み方手順を説明した手ほどき課題の前頭前野の活動領域を比較した。結果、手ほどき課題時は試行錯誤課題時に比べ、より広範囲の脳活動(有意なオキシヘモグロビン濃度長の増加)が認められた。手工芸の教授時に作り方の手順を示すことが、試行錯誤させるよりも広範囲に脳を賦活させ、統合失調症患者にみられる前頭前野の血流低下の改善に影響を与えることが示唆された。(著者抄録)

本研究では、療育者が日常生活のなかで把握できなかった重症心身障害児・者の応答を、脳の賦活の側面から評価することを目的として、近赤外分光法(Near-infrared spectroscopy;NIRS)を用いて検討した。対象は重症心身障害児施設に入所中の2事例、計測課題は施設職員が療育方針を検討するうえで必要性が高い内容とした。事例1は入所前に父親が我が子の表情が豊かになるととらえていた特定の音楽(標的課題)と別の音楽、事例2は眼鏡装用時(標的課題)と裸眼時を課題とし、おのおのの賦活範囲の広さを比較した。結果は、両事例とも標的課題のほうが脳の賦活範囲が広かった。このように彼らの刺激に対する応答を、明確な脳の賦活の様相の違いとして計測することができた。NIRS計測結果を、彼らの応答と結論づけることは早計であるかもしれないが、彼らへの療育的介入を実践するための評価として役立てることができると期待できる。(著者抄録)

Clinical studies have shown that functional motor recovery after stroke may be facilitated by mirror therapy (MT). However, its underlying mechanism is uncertain. In this study, we examined brain activation during unilateral hand movement in 5 right-handed healthy subjects (1 male and 4 females) with or without viewing a mirror reflection of the moving hand (MT). We measure d the changes in the concentration of oxygenated hemoglobin in the primary sensorimotor cortex (SMC) using near-infrared spectroscopy. We calculated the laterality index (LI) using the extent of activation in the right and left SMCs. The LIs (± standard error of mean) during right hand grasping without and with MT were 0.17± 0. 11 (left SMC predominance) and -0.42 ± 0.24 (right SMC predominance), respectively (p &lt 0.05). However, there was no significant difference in LIs during left hand grasping without and with MT (0.02 ± 0.05 and 0.08 ± 0.05, respectively). The findings suggest that MT is more effective when it is used for dominant right hand movement, and this phenomenon may be the related to the different manipulability between the dominant and non-dominant hands.

Spatial cognition is right-hemisphere dominant in right-handers, but hemispheric laterality in left-handers is not fully understood. Using near-infrared spectroscopy, we compared cerebral activations in the frontal and parietal lobes during a mental rotation task between seven healthy right-handed and seven healthy left-handed women. Cerebral laterality during the spatial cognition task was evaluated as balance in the extent of activation areas between the two cerebral hemispheres, using the right-hemispheric dominance index (RI). RIs of right-handers showed right-hemispheric dominance (RI>0) in both frontal (RI=0.31+/-0.25) and parietal (RI=0.28+/-0.37) lobes, while left-handers showed slight left-hemispheric dominance (RI<0) in both frontal (RI=-0.13+/-0.18) and parietal (RI=-0.22+/-0.22) lobes. The left-handers exhibited significantly larger amplitudes of activation at the channels overlying the left-superior parietal lobule, whereas the right-handers did not show such amplitude differences. These findings suggest a difference in cerebral hemispheric laterality for spatial cognition between left- and right-handers.

近赤外分光法(Near-infrared spectroscopy;NIRS)は無侵襲脳機能マッピング法であり,脳を透過した近赤外光の光量変化から,神経活動に依存して変化するヘモグロビン濃度変化量を計測する方法である。この計測法は簡便で非拘束性が高く,計測姿勢等の制限が小さいという利点から,リハビリテーションをはじめとした領域において様々な実験課題による計測が行われており,そのためNIRS データの統計方法も多様に報告されている。本稿では,計測データの統計処理以前に熟知している必要のある,フィルタや移動平均処理といった基本的なNIRS データの信号処理について概説した。

Motor functional recovery after stroke may be attributable to cerebral reorganization. We used near-infrared spectroscopy, which measures non-invasively the changes in oxy- and deoxy-hemoglobin concentrations in response to neural activation, for monitoring cerebral activation in stroke patients, and investigated the longitudinal changes in functional laterality of activations in the primary sensorimotor cortex during unilateral audio-paced (1 Hz) hand movement. We examined five ischemic stroke patients (4 females and 1 male, 52-67 years old) with mild to moderate hemiparesis at acute stages and chronic stages at least 1 month later. Normal subjects (3 females and 2 males, 47-63 years old) were also included. Unilateral hand movement activated predominantly the contralateral primary sensorimotor cortex in the normal subjects and the stroke patients when they moved unaffected hand. Affected hand movements activated bilateral sensorimotor cortices early after stroke (< 25 days of stroke onset), whereas the activation pattern returned toward normal at later periods (> 35 days). The contralaterality index (0.34 +/- 0.12 in normal control) was reduced at early periods (0.00 +/- 0.03, p < 0.01) after stroke, and returned to normal (0.35 +/- 0.24) as motor function recovered. These findings suggest that a transient increase in motor activation in the ipsilateral intact hemisphere within 1 month may play an important role in the recovery from motor dysfunction after stroke.

文字認識やパターン認識などに用いられる画像処理技術である二値化処理と細線化処理を適用することで、分散培養・組織培養における、枝分かれし、曲線的で複雑に伸長する神経突起長をより正確に計算する方法を組み込んだソフトウェア(Mneurites)を創作した。後根神経節の分散培養を用いてこの方法を従来の方法と比較し、より正確な結果を得ることができた。らせん神経節や後根神経節の小片培養における神経突起の計測を行った。従来困難であった小片培養においてもこの方法が適用できた。神経の発生、再生などの仕組みを解析する上で非常に有用であることが示唆された。

Unit discharges and local field potentials (LFPs) were recorded simultaneously in primary auditory cortex (A1) of a guinea pig for cross-correlograms and cross correlation functions of LFPs were compared. From the results, the adequate periods of signals applied for cross correlation analysis were discussed. Consequently this application period must be selected correspondingly to temporally changing response periods.

We studied how hippocampus affects auditory cortex neurons by means of single-unit recording. The population of responses to click-sound in the guinea-pig auditory cortex was estimated by resampling method, and the effects on neural response of hippocampal activation that evoked by electrical stimulation were determined. As a result, the firing rate in layers II/III decreased, and in layers V/VI increased.