[Spinal and muscular evoked response following single stimulation of the motor cortex of the rat].
The general characteristics of motor evoked potentials recorded from muscle and spinal cord in response to single electrical stimulation of motor cortex were examined in 30 rats. 5 other rats were additionally examined before and after full muscle relaxation, to differentiate the volume-conducted muscle response from spinal cord responses. The first positivity (P1) recorded from the lower thoracic cord following anodal stimulation was 1.1 +/- 0.1 ms and the second positivity (P2) was 2.1 +/- 0.2 ms. P1 was present in 11 animals and P2 in 20. The later components after 2.3 ms latency recorded from the epidural spinal electrode were lost with full muscular relaxation and seem to originate from volume conducted muscular activity. A relatively stable early MEP muscle response (6.1 +/- 0.9 ms) was observed in contralateral lower extremity muscles of all animals. Following this early response, a late MEP muscle response (16.0 +/- 1.9 ms) has been recorded in 43% of all animals. This relatively inconstant and multiphasic late muscle response disappeared during vibration of same extremity tendons and has similar characteristics as Hoffmann's reflex response. Additionally, with increasing stimulus intensities, the amplitude ratio of early to late response was similar to M response/H reflex amplitude ratio. The results suggest that the late MEP muscle response is probably the result of a reflex response caused by the first/early descending volley and traveled back to the spinal cord possibly through the Ia afferents similar to that in the H-reflex.
Zileli
M
M
Neurochirurgische Universitätsklinik, Erlangen-Nürnberg.
Schramm
J
J
D000818:Animals; D004292:Dominance, Cerebral / Q000502:physiology; D005071:Evoked Potentials; D006181:H-Reflex; D006614:Hindlimb / Q000294:innervation; D009044:Motor Cortex / Q000502:physiology*; D009132:Muscles / Q000294:innervation*; D051381:Rats; D011930:Reaction Time / Q000502:physiology; D013116:Spinal Cord / Q000502:physiology*
Spinale und muskuläre Reizantwort nach Einzelreizung des motorischen Kortex der Ratte.