S214

14-16 INPUT-OUTPUT RELATIONSHIP OF THE DIGITS AREA OF MOTOR CORTEX FOLLOWING DENERVATION OF FORELIMB NERVES. AK10 MORI YAYOI YAMAGUCHI, TATSU m*, HISAO HIRABA AND RHYUJI SUMINO, Dept

-.--..-d-

Kanda-SuGadai, . of Physiol., Sch of Dent Nihon Univ 1-8-13

* Chiyoda-ku, /-_-A

Tokyo 101, Dept. of Neurol., -A-

Tokyo Metoropolitan Institute for Neurosciences, 2_6 Musashidai, Fuchu, Tokyo 183, Japan

Input-output relationship of the area 4 of the motor cortex (MCx) in cats were examined under nembutal anesthesia(35mg/kg,i.p.). Through a single in-glass

tungsten- pipette, a micro-electrode was inserted into the depths of the MCx for

recording unitary spikes and intracortical-microstimulation(ICMS). The receptive fiels (RFs) of the control animals without nerve section were identified using pe- ripheral natural stimulation under ketamine anesthesia (3mg/kg/h.,i.m.). The fore- limb nerves (the median, radial, ulnar and musculocutaneous nerves) were dener- vated under nembutal anesthesia(35mg/kg,i.p.).

One month after denervation, neurons within the digits area in the motor cortex lost their RFs. ICMS to digits area of MCx produced shoulder movements. In addition, ICMS to some few neurons in the digits area produced neck movements. There were a reorganizations of the cortical motor effective zones from the digits to shoulder or neck. The size of the cortical motor effective zone of the shoulder for ICMS to the digits area in the MCx was clearly larger than that in the contra1 animals.

14- 17 EFFECTS OF DOPAMINERGIC DRUGS ON LOCAL CEREBRAL GLUCOSE UTILIZATION IN THE ROLLING MOUSE NAGOYA. ITO. DM

. . . . . . . . f Univdtv 60.3 1 1 s _ _

We have previously reported that local cerebral glucose utilization (LCGU) is markedly increased in the basal ganglia of the Rolling mouse Nagoya (rolling), a neurological mutant with movement disorders. The LCGU increases are seen bilaterally in the globus pallidus (GP), entopeduncular nucleus (EP), substantia nigra pars compacta (SNc) and pars reticulata(SNr), and subthalamic nucleus (STN). Since these findings are quite similar to the effect of apomorphine, a dopaminergic (DAergic) receptor agonist, we investigated the effects of apomorphine and haloperidol, a DAergic receptor antagonist, on LCGU of rolling. Apomorphine (2mg/kg,i.p.) reduced the abnormally elevated LCGU in the basal ganglia structures of rolling except the STN, while it increased LCGU of the basal ganglia of normal control mice as have been reported in normal rats. Only STN of rolling showed no remarkable alteration in LCGU by apomorphine. Haloperidol (lmg/kg,i.p.) caused no changes in the abnormally increased LCGU in the basal ganglia of rolling, whereas the control mice reduced LCGU in these structures. These findings indicate that, in rolling, DAergic function is also involved in the dysfunction of the basal ganglia, and plays an important role in the LCGU alterations.

14-181s FINGER MOVEMENT CONTROLLED BY CUTANEOUS AFFERENT ACTlVlTlES DURING ACTIVE TOUCH FOR TEXTURE DlSCRIMINATION IN MAN? SHINOBU TOMA AND YOSHIO NAKAJIMA,

Department of Physiology, School of Medicine, Chiba University, 1--8-l, Inohana, Chiba 260, Japan

Using a microneurographic technique, we studied the finger movements and discharge patterns of cutaneous afferents during texture discrimonation of four different surfaces in roughness in young healthy and blindfolded subjects. Single FAI and SAI activities from the finger tip were recorded simultaneously with signals of finger movement, touch friction and pressure. A stereotyped finger scanning movement at a constant speed was observed. The touch pressure during the scanning depended on the roughness, i. e. the lighter pressure on the rougher surface. FAI fired in synchronous with the touch friction measured by an accelerometer in proportion to the roughness. SAI fired at relatively regular and low rates around 20Hz independent of the surface. However, instantaneous SAI discharge rates were varied responding to a fine variation of touch pressure. These results may indicate that active finger movement is controlled to enhance the proper sensitivity of the FAI receptor which may transmit the roughness information. SAI activity is supposed to regulate the touch pressure at the level adequate for the finger scanning and perception.