Karthik S. Murthy

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Cross-correlation analysis of the naturally occurring discharges of gamma-motoneurones to gastrocnemius and soleus muscles has revealed a tendency towards synchronized firing in the decerebrated, spinal cat. The primary feature of the cross-correlation between two gamma-motoneurones is a symmetrical peak centred at time zero with reference to discharges at(More)
Responses of muscle afferent nerve fibres to tendon taps of digital muscles in the human can be recorded with surface electrodes attached to the skin over the nerve at the wrist. Using an effectively monopolar recording method, a considerable improvement in signal amplitude is achieved with simultaneous reduction in mechanical artefacts using differential(More)
Environmental exposure to lead (Pb) is known to affect the developing nervous system causing cognitive deficits in children. The diffusible nitric oxide (NO) is a biological messenger known to be involved in brain development. We examined the developmental changes of neuronal nitric oxide synthase (nNOS) in cerebellum and hippocampus of developing rat brain(More)
The naturally occurring background discharges of gamma-motoneurones to gastrocnemius and soleus in the decerebrated, spinal cat show a degree of short-term synchrony which is absent when the spinal cord is intact. The characteristics of this synchrony and the mechanism producing it have been examined in the preceeding paper (Ellaway & Murthy, 1985).(More)
Twitch and tetanic contractions of single motor units of the cat peroneus tertius muscle were examined after application of a test allowing their identification as either fast fatigable (f.f.) or fast fatigue-resistant (f.r.) or fast intermediate (f.i.) or slow units as established by Burke, Levine, Tsairis & Zajac (1973). The test was found to leave two(More)
Motor units of the cat peroneus tertius muscle were systematically analyzed using the criteria established by Burke et al. (1973). On the basis of their speed of contraction and resistance to fatigue, 121 (97%) of 125 motor units examined in ten adult cats could be classified as belonging to one of four types: fast-fatigable (FF), fast-resistant (FR),(More)
1. Physiological tests were used to identify skeletofusimotor or beta axons to the cat peroneus tertius muscle in order to assess the proportion of beta axons in the motor supply to this muscle. 2. Static beta axons (beta S) were identified by: (a) observation of a delay between the complete block of extrafusal contraction and the failure of spindle(More)
The effect of varying the fusimotor bias on the muscle spindle responses to light tendon taps has been studied in normal human volunteers using surface electrodes at the wrist for recording whole nerve activity. Reinforcement manoeuvres were found to increase the sensitivity of the afferent responses to the mechanical stimulus. Such sensitisation was found(More)
A protocol has been developed to use the GE 8800 scanner and its resident programs to calculate stereotactic coordinates, which has made it possible to use any stereotactic apparatus without modifying the apparatus in order to introduce a cannula into any lesion visualized on a computed tomographic (CT) scan to biopsy tumors, drain abscesses, implant(More)