S172

1551 REORGANIZATION OF THE CORTICO-CORTICAL PROJECTIONS TO THE DIGITS AREA OF THE MOTOR CORTEX FOLLOWING DENERVATION OF THE PERIPHERAL NERVE

IN THE CAT. AKIO MORI 1 , YAYOI YAMAGUCHI 1 , TATSU FUWA 2 AND RHYUGI -SUMINO I,

l~ept.of Physiol.Sch. of Nihon University, Chiyoda-ku Tokyo, Japan and 2Dept. of

Neurol.. Tokyo Metoropolltan Insti. for Neurosci., Tokyo, Japan

We examined the ipsilateral and contralateral cortio-cortleal connections to the digits area of the motor cortex (MCx) following periperal nerve lesion using HRP techniques. The adult cats were used in this experlmen~. HRP-labeled neurons of the normal cat were located in the area 4 of the MCx, SI (areas i, 2, 3a and 3b), SII. SIr. ireas 6a~ and 5 of the iosilateral cortex. On the other hand, small ~umbers of HRP-labeled neurons of the contralateral cortex were located in area 4 of the MCx. However, at 2 and 3 months after denervatlon, many HRP-labeled neurons were located in area 4, 6a. SI(I. 2, 3a. 3h), SII. SIII, SIV, 5, Id of the Ipsilateral cortex. On the contralateral side of the cortex. HRP-labeled neurons were located in areas 4, SI (3a, 3h), SII, SIV, SV,Ig and 6a. These neurons were located in layers II,III and V. Most of these neurons were found in layer III. The finding that the MCx region receives parallel inputs from various sites in the

sensory cortex suggests that these projection may have a very important role in the reorganization of the digits area of the bICx following deprivation of peripheral nerves.

1 5 5 2 UNIT ACTIVITY OF TtlALAMIC NEURONS PRQ,IECTING ONTO TIlE PREFRONTAL CORTEX IN TIIE MONKEY. IKUO TANIBUCtII 1 AND KOIINOSUK~ . I INNAI.

1 D r p t . o f P h y s i o l . , Fukui Med. Schoo-~, ~ ~ . ~ and ~Dept . o f P h y s i o l . , Sh iga Univ. bled. S c i . , Ohtsu , Sh iga 520 -21 , J a p a n

In an unanesthetized Japanese monkey, thalamic neurons proJecting onto wlrlous areas" of the prefrontal cortex were identified, and their activities were investigated during tlle performance of a few kind of tasks. Light stimulus increased the discharge rate of the thalamlc neurons in tlle medlodorsal nucleus projecting onto the area rostral to the inferior llmb of the arcuate sulcus.

J 553 Increases in regional cerebral blood flow in human primary motor cortex

related to ipsilateral hand movements. Ryu~a Kawa$hima and Hiroshi

Fukuda, DePt. Nucl. Med. & Radiol., Inst. of Development, Aqinu & Cancer, Tohoku

Univ. Selrvocho, Sendal 980, JaDan.

In two Positron Emission Tomography~tudies of very similar unilateral

finger movements, we found somatosensory discrimination of length activated

ipsilateral primary motor area (MI), but discrimination of shape did not. This

raises doubt that the ipsilateral M1 activation was related to the character of

the movements. A correlation analysis of rCBF showed strong correlations between

the field in the ipsilateral M1 and fields in the premotor area, prefrontal area

and posterior cingulate gyrus indicating that these areas together with the

ipsilateral M1 constitute a task related active network.