- Email: [email protected]
Synaptic connection from muscle afferents to the motoneurons of various leg muscles in man
$130
F~02 THE PERIPHERAL NERVE INVOLVEMENTIN SPINOCEREBELLARDEGENERATION
MANO Y, SASAKIBARA T, TAKAYANAGI T, Nara Medical University, Department of Neurology, 840, Shijo-co, Kashihara-city, Nara-ken, 634 Japan
Spinocerebellar degeneration (SCD) is a disease which causes degenerative changes in the spinal cord, brain stem, and cerebellum. The lesions may extend more widely. We studied this tendency e l e c t r o p h y s i o l o g i c a l l y in the presence of peripheral nerve disorders in 15 cases of SCD. The incidence of abnormalities was s l i g h t l y higher in the sensory nerve than in the motor nerve and was s l i g h t l y higher in the peripheral areas than in the proximal areas in both the motor and sensory nerves. Most patients with OPCA, a type of SCD, had a h i s t o r y of having the disease f o r many years and showed a delay in conduction of the peripheral nerve. Therefore, we considered these to be cases of m u l t i p l e system atrophy in a broad sense. Patients with t a l i pes cavus with muscular atrophy had severe peripheral nerve disorders.
F203 SYNAPTICCONNECTIONFROMMUSCLEAFFERENTS TO THE MOTONEURONSOF VARIOUS LEG MUSCLES IN MAN
MAO CC, ASHBY P., WANGM., McCREA Dz P l a y f a i r Neuroscience Unit, University of Toronto, Canada Cross-correlations between s ti m u l i delivered to peripheral nerves (input t r a i n ) and the discharges of single v o l u n t a r i l y activated motor units (output t r a i n ) can provide information about f a c i l i t a t o r y and i n h i b i t o r y projections to single spinal motoneurons in man. Deductions about the shape and r e l a t i v e amplitude of the evoked compound postsynaptic p o t e n t i a l s can be made from the p r o f i l e of the cross-correlogram. This technique has been used to explore the projections of low threshold (group I muscle afferents to various species of motoneurons supplying human leg muscles in man. Low threshold afferents from a given muscle were found to make e x c i t a t o r y connections to a l l of sampled motor units of that muscle. This was true f o r a l l muscles examined and is presumed to represent the group la composite EPSP. The most powerful homonymous f a c i l i t a t i o n was observed in soleus motoneurons during stimulation of low threshold afferents in the t i b i a l nerve. F a c i l i t a t o r y connections were also found between certain synergists, although the pattern d i f f e r s from that reported in the cat. Reciprocal i n h i b i t i o n was demonstrated from afferents in the t i b i a l nerve to ~ i b i a l i s a n t e r i o r motoneurons, but, s u r p r i s i n g l y , soleus motoneurons were f a c i l i t a t e d rather than i n h i b i t e d by low threshold afferents in the common peroneal nerve. Quadriceps motoneurons received f a c i l i t a t o r y connections from low afferents in the common peroneal nerve in man. I t is l i k e l y that these r e f l e x pathways are involved in the control of posture and locomotion in man.
F~02 THE PERIPHERAL NERVE INVOLVEMENTIN SPINOCEREBELLARDEGENERATION
MANO Y, SASAKIBARA T, TAKAYANAGI T, Nara Medical University, Department of Neurology, 840, Shijo-co, Kashihara-city, Nara-ken, 634 Japan
Spinocerebellar degeneration (SCD) is a disease which causes degenerative changes in the spinal cord, brain stem, and cerebellum. The lesions may extend more widely. We studied this tendency e l e c t r o p h y s i o l o g i c a l l y in the presence of peripheral nerve disorders in 15 cases of SCD. The incidence of abnormalities was s l i g h t l y higher in the sensory nerve than in the motor nerve and was s l i g h t l y higher in the peripheral areas than in the proximal areas in both the motor and sensory nerves. Most patients with OPCA, a type of SCD, had a h i s t o r y of having the disease f o r many years and showed a delay in conduction of the peripheral nerve. Therefore, we considered these to be cases of m u l t i p l e system atrophy in a broad sense. Patients with t a l i pes cavus with muscular atrophy had severe peripheral nerve disorders.
F203 SYNAPTICCONNECTIONFROMMUSCLEAFFERENTS TO THE MOTONEURONSOF VARIOUS LEG MUSCLES IN MAN
MAO CC, ASHBY P., WANGM., McCREA Dz P l a y f a i r Neuroscience Unit, University of Toronto, Canada Cross-correlations between s ti m u l i delivered to peripheral nerves (input t r a i n ) and the discharges of single v o l u n t a r i l y activated motor units (output t r a i n ) can provide information about f a c i l i t a t o r y and i n h i b i t o r y projections to single spinal motoneurons in man. Deductions about the shape and r e l a t i v e amplitude of the evoked compound postsynaptic p o t e n t i a l s can be made from the p r o f i l e of the cross-correlogram. This technique has been used to explore the projections of low threshold (group I muscle afferents to various species of motoneurons supplying human leg muscles in man. Low threshold afferents from a given muscle were found to make e x c i t a t o r y connections to a l l of sampled motor units of that muscle. This was true f o r a l l muscles examined and is presumed to represent the group la composite EPSP. The most powerful homonymous f a c i l i t a t i o n was observed in soleus motoneurons during stimulation of low threshold afferents in the t i b i a l nerve. F a c i l i t a t o r y connections were also found between certain synergists, although the pattern d i f f e r s from that reported in the cat. Reciprocal i n h i b i t i o n was demonstrated from afferents in the t i b i a l nerve to ~ i b i a l i s a n t e r i o r motoneurons, but, s u r p r i s i n g l y , soleus motoneurons were f a c i l i t a t e d rather than i n h i b i t e d by low threshold afferents in the common peroneal nerve. Quadriceps motoneurons received f a c i l i t a t o r y connections from low afferents in the common peroneal nerve in man. I t is l i k e l y that these r e f l e x pathways are involved in the control of posture and locomotion in man.