49 research outputs found
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Detection thresholds to stimulation of ventrobasal complex in cats.
Cats were trained to indicate, by bar pressing for food rewards, their detection of stimulation of the ventrobasal (VB) complex delivered through implanted bipolar electrodes. By varying stimulus intensity it was possible to determine thresholds for detection. Scaling stimulus intensity relative to the appearance of a minimal evoked potential allowed comparisons between animals and also comparisons with results obtained by stimulation of peripheral nerve. Animals could detect VB stimulation, but only at stimulus intensities consistently stronger than those required for minimal appearance of an evoked response in ipsilateral primary somatosensory cortex. Results of VB activation differed from cutaneous nerve effects in that VB detection thresholds were markedly influenced by stimulus frequency. They were lowest at frequencies above 30 Hz and increased greatly at lower frequencies. Discomfort or pain did not seem to result even from relatively high stimulus intensities. The results compare well with observations obtained from stimulation of VB in humans. The appearance of an evoked cortical response is not necessarily correlated with behavior. Under appropriate conditions, behavior can be elicited predictably with minimal electrocortical activity; under other conditions detection may be absent even when large numbers of cortical neurons are activated. We suggest that regions of the cerebral cortex receiving thalamocortical projections from VB may not be essential in the detection process
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Detection thresholds to stimulation of ventrobasal complex in cats.
Cats were trained to indicate, by bar pressing for food rewards, their detection of stimulation of the ventrobasal (VB) complex delivered through implanted bipolar electrodes. By varying stimulus intensity it was possible to determine thresholds for detection. Scaling stimulus intensity relative to the appearance of a minimal evoked potential allowed comparisons between animals and also comparisons with results obtained by stimulation of peripheral nerve. Animals could detect VB stimulation, but only at stimulus intensities consistently stronger than those required for minimal appearance of an evoked response in ipsilateral primary somatosensory cortex. Results of VB activation differed from cutaneous nerve effects in that VB detection thresholds were markedly influenced by stimulus frequency. They were lowest at frequencies above 30 Hz and increased greatly at lower frequencies. Discomfort or pain did not seem to result even from relatively high stimulus intensities. The results compare well with observations obtained from stimulation of VB in humans. The appearance of an evoked cortical response is not necessarily correlated with behavior. Under appropriate conditions, behavior can be elicited predictably with minimal electrocortical activity; under other conditions detection may be absent even when large numbers of cortical neurons are activated. We suggest that regions of the cerebral cortex receiving thalamocortical projections from VB may not be essential in the detection process
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EFFECTS OF CUTANEOUS AND MUSCLE SENSORY NERVE VOLLEYS IN AWAKE CATS: A STUDY IN PERCEPTION.
The hypothesis that discharges from afferent nerves from muscle stretch receptors do not participate in kinesthesis has been substantiated by test of discrimination thresholds. In awake, unrestrained cats, nerve stimulation activating group I and most group II sensory fibers (from muscle spindles and Golgi tendon organs) in pure muscular nerves failed to evoke sensory discrimination. Cutaneous nerve stimulation in the same animals produced sensory discrimination even below intensities required to elicit detectable nerve thresholds
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EFFECTS OF CUTANEOUS AND MUSCLE SENSORY NERVE VOLLEYS IN AWAKE CATS: A STUDY IN PERCEPTION.
The hypothesis that discharges from afferent nerves from muscle stretch receptors do not participate in kinesthesis has been substantiated by test of discrimination thresholds. In awake, unrestrained cats, nerve stimulation activating group I and most group II sensory fibers (from muscle spindles and Golgi tendon organs) in pure muscular nerves failed to evoke sensory discrimination. Cutaneous nerve stimulation in the same animals produced sensory discrimination even below intensities required to elicit detectable nerve thresholds
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Motor versus sensory neuron regeneration through collagen tubules.
Differences in regeneration of sensory and motor nerves were studied in rats to determine the effects of entubulation with collagen conduits. The rat sciatic nerve was repaired either with a 10-mm saline-filled gap or with a no-gap end-to-end repair cuffed within collagen tubules. These repairs were compared with the standard epineurial repairs. The populations of regenerated motor and sensory neurons in the peroneal nerves of all repairs were compared against the populations of normal peroneal neurons using horseradish peroxidase retrograde labeling. The epineurial repair resulted in regeneration of 65 percent (409 +/- 150) of motor neurons and 79 percent (2127 +/- 516) of sensory neurons (n = 6). The no-gap end-to-end repair in a collagen tubule resulted in regeneration of 53 percent (338 +/- 203) of motor and 70 percent (1893 +/- 794) of sensory neurons (n = 7). In the 10-mm gap repair, only 6.2 percent (39 +/- 18) of motor neurons but 63 percent (1710 +/- 557) of sensory neurons regenerated (n = 5). These results show that collagen entubulation supports nerve regeneration in end-to-end nerve repairs comparably to standard epineurial suture repairs. With the 10-mm gap repairs in collagen tubules, sensory neurons regenerated consistently better than motor neurons in the same environment. Therefore, intrinsic differences exist between motor and sensory neuron regeneration in the same nerve
Evaluation of topiramate as an anti-hyperalgesic and neuroprotective agent in the peripheral nervous system
Banal nationalism and consumer activism: the case of #BoycottGermany
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