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Firing motoneuron: relationship between firing frequency and excitability
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F178 CUTANEOUSSENSORY RESPONSESWITH CERVICAL RADICULOPATHIES
KUCHERA ML, WILBOURN A, K i r k s v i l l e College of Osteopathic Medicine, K i r k s v i l l e , MO, USA; and Cleveland C l i n i c Foundation , Cleveland, OH, USA The results of Bonney's work in 1959 c l e a r l y show that cutaneous sensory responses (CSR) are normal in cervical root avulsions proximal to the dorsal root ganglia. Less well documented, however, is the status of the CSR with r a d i c u l o pathy. We reviewed fourty cases in which compressive cervical radiculopathy was demonstrated on needle examination (NE) including fourteen C5-6~ twenty C7, and sixteen C8-TI radiculopathies. Diagnostic confirmation was established by paraspinal involvement on NE (35%) and radiographic documentation (66%) in 77% of these cases. ~ B i l a t e r a l SCR analysis of the ulnar (40/40), radial (37/40), and l a t e r a l cutaneous (21/40) nerves as well as the median nerve recording thumb (34/40), middle (40/40), and index (40/40) fingers was performed. Side-to-side v a r i a b i l i t y (STSV) was calculated to express reduction or elevation of CSR amplitudes on the side of the radiculopathy compared to the non-affected limb. S t a t i s t i c a l evaluation of the data revealed no s i g n i f i c a n t STSV with a l l STSV averages f or each nerve +/- 10%. Reduced i n d i v i d u a l STSV of 30% or more occurred in 10/269 values as compared with 9/269 values showing an elevation to the same degree. These data f a i l to demonstrate any s t a t i s t i c a l l y s i g n i f i c a n t STSV in CSR amplitudes in patients with documented C5-6, C7, or C8-TI radiculopathies.
F179 FIRING MOTONEURON: RELATIONSHIP BETWEEN FIRING FREQUENCYArID EXCITABILITY KUDINA L.P., I n s t i t u t e f o r Problems of Information Transmission, U.S.S.R. Academy of Sciences, Moscow, U.S.S.R. The e x c i t a b i l i t y of human v o l u n t a r i l y activated motoneurons of m. soleus and m. rectus fem. was tested by group la a f f e r e n t v o l l e y evoking weak H - r e f l e x . For the estimation of motoneuron response p r o b a b i l i t y peri-stimulus h i s t o grams of single MUs were p l o tt e d and a f i r i n g index was calculated as c r i t e r i on of motoneuron e x c i t a b i l i t y . Mean f i r i n g frequency of MUs under study was 4-11/s. I t was found that the higher the f i r i n g frequency the lower the f i r i n g index of the MU. The highest f i r i n g index was obtained f o r s i l e n t MUs which were re c ru i t e d in response to a f f e r e n t v o l l e y . The analysis of e x c i t a b i l i t y change during interspike i n t e r v a l showed the a f f e r e n t v o l l e y to become e f f e c t i v e only when i t a r r i v e d at 40-60% of the elapsed mean interval ("responsive zone"). The percentage duration of "responsive one" of the interspike interval was decreased with increase of the motoneuron f i r i n g frequency, I t is concluded that f i r i n g frequency is one of the factors c o n t r o l l i n g the e x c i t a b i l i t y of single motoneurons and t h e i r populations, The e f f e c t of the same a f f e r e n t v o l l e y is modulated in d i f f e r e n t ways i f i t arrives at motoneuron f i r i n g with d i f f e r e n t frequency. Thus, the motoneuron f i r i n g frequency affects input-output r e a l t i o n during i n t e r a c t i o n of inflows from two d i f f e r e n t sources - descending and a f f e r e n t ones.
F178 CUTANEOUSSENSORY RESPONSESWITH CERVICAL RADICULOPATHIES
KUCHERA ML, WILBOURN A, K i r k s v i l l e College of Osteopathic Medicine, K i r k s v i l l e , MO, USA; and Cleveland C l i n i c Foundation , Cleveland, OH, USA The results of Bonney's work in 1959 c l e a r l y show that cutaneous sensory responses (CSR) are normal in cervical root avulsions proximal to the dorsal root ganglia. Less well documented, however, is the status of the CSR with r a d i c u l o pathy. We reviewed fourty cases in which compressive cervical radiculopathy was demonstrated on needle examination (NE) including fourteen C5-6~ twenty C7, and sixteen C8-TI radiculopathies. Diagnostic confirmation was established by paraspinal involvement on NE (35%) and radiographic documentation (66%) in 77% of these cases. ~ B i l a t e r a l SCR analysis of the ulnar (40/40), radial (37/40), and l a t e r a l cutaneous (21/40) nerves as well as the median nerve recording thumb (34/40), middle (40/40), and index (40/40) fingers was performed. Side-to-side v a r i a b i l i t y (STSV) was calculated to express reduction or elevation of CSR amplitudes on the side of the radiculopathy compared to the non-affected limb. S t a t i s t i c a l evaluation of the data revealed no s i g n i f i c a n t STSV with a l l STSV averages f or each nerve +/- 10%. Reduced i n d i v i d u a l STSV of 30% or more occurred in 10/269 values as compared with 9/269 values showing an elevation to the same degree. These data f a i l to demonstrate any s t a t i s t i c a l l y s i g n i f i c a n t STSV in CSR amplitudes in patients with documented C5-6, C7, or C8-TI radiculopathies.
F179 FIRING MOTONEURON: RELATIONSHIP BETWEEN FIRING FREQUENCYArID EXCITABILITY KUDINA L.P., I n s t i t u t e f o r Problems of Information Transmission, U.S.S.R. Academy of Sciences, Moscow, U.S.S.R. The e x c i t a b i l i t y of human v o l u n t a r i l y activated motoneurons of m. soleus and m. rectus fem. was tested by group la a f f e r e n t v o l l e y evoking weak H - r e f l e x . For the estimation of motoneuron response p r o b a b i l i t y peri-stimulus h i s t o grams of single MUs were p l o tt e d and a f i r i n g index was calculated as c r i t e r i on of motoneuron e x c i t a b i l i t y . Mean f i r i n g frequency of MUs under study was 4-11/s. I t was found that the higher the f i r i n g frequency the lower the f i r i n g index of the MU. The highest f i r i n g index was obtained f o r s i l e n t MUs which were re c ru i t e d in response to a f f e r e n t v o l l e y . The analysis of e x c i t a b i l i t y change during interspike i n t e r v a l showed the a f f e r e n t v o l l e y to become e f f e c t i v e only when i t a r r i v e d at 40-60% of the elapsed mean interval ("responsive zone"). The percentage duration of "responsive one" of the interspike interval was decreased with increase of the motoneuron f i r i n g frequency, I t is concluded that f i r i n g frequency is one of the factors c o n t r o l l i n g the e x c i t a b i l i t y of single motoneurons and t h e i r populations, The e f f e c t of the same a f f e r e n t v o l l e y is modulated in d i f f e r e n t ways i f i t arrives at motoneuron f i r i n g with d i f f e r e n t frequency. Thus, the motoneuron f i r i n g frequency affects input-output r e a l t i o n during i n t e r a c t i o n of inflows from two d i f f e r e n t sources - descending and a f f e r e n t ones.