Correlation analysis of muscle receptor discharge during active contractions of the cat medial gastrocnemius muscle.
The spike trains of afferent fibers innervating muscle spindles and Golgi tendon organs in the medial gastrocnemius muscle were recorded during spontaneous contractions in either decerebrate cats or decapitate cats treated with L-dopa. For each afferent fiber, the approximate location of its receptor within the muscle was determined. Cross-correlation histograms were compiled from the simultaneously recorded spike trains of pairs of afferent fibers (Ia, Ib, spindle II) to determine if the degree of temporal correlation in their discharge was related to the mutual proximity of the receptors they innervated within the muscle. The frequency of occurrence and degree of correlated activity between pairs of muscle afferents, regardless of receptor type, was much greater in the decerebrate preparations than in the decapitate-L-dopa preparations. However, in all cases, the extent of correlated activity appeared to be unrelated to the relative locations of the receptors. The results suggest that the degree to which the discharge patterns of muscle receptors display temporal correlations and thereby potentially reinforce the "sensory partitioning" (5) of their parent muscle is strongly dependent on the type of preparation used, and thus by inference, dependent on the central state of the animal.
D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002415:Cats; D003655:Decerebrate State; D004594:Electrophysiology; D006614:Hindlimb; D008465:Mechanoreceptors / Q000502:physiology*; D009119:Muscle Contraction; D009470:Muscle Spindles / Q000502:physiology; D009132:Muscles / Q000502:physiology*; D009412:Nerve Fibers / Q000502:physiology