Elsevier

Brain Research

Volume 46, 13 November 1972, Pages 43-54
Brain Research

Reticular ascending activation of frontal cortical neurons in rabbits, with special reference to the regulation of deglutition

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Abstract

Under light ether anesthesia, long-lasting bouts of swallowing were produced by repetitive stimulation of a discrete pontine reticular area lying dorsolaterally to the superior olive in rabbits. Extracellular exploration of neurons in the frontal cortex was performed in each animal when paralyzed and maintained with artificial respiration. Analysis of whether and in what manner these neurons responded to such pontine stimuli was performed.

  • (1)

    Of 208 cortical neurons examined, 186 responded consistently to the pontine stimulus, the remainder showing no response. Among those that responded, 151 did so with a single action potential, while the others showed multiple discharges.

  • (2)

    Overall latencies of response of these neurons ranged from 2.3 to 63.4 msec with a mean of 10.49 msec (S:9.35). Latencies of those responding with a single action potential had a mean value of 8.58 msec (S: 6.9); those responding with multiple discharges had latencies with a mean of 18.6 msec (S: 13.3). In the latter neurons, the latency and the number of spikes were strongly dependent on stimulus intensity, i.e., a weak stimulus yielded a response of longer latency and with fewer spikes. However, several neurons showed a reciprocal relation with stimulus intensity.

  • (3)

    Some preliminary evidence for antidromic as well as orthodromic activation of these neurons is given. Evidence that there may be various polysynaptic corticopetal routes from the ipsi- and contralateral pontine reticular formation is presented.

  • (4)

    These results, together with those obtained previously, are discussed in relation to cortico-brain stem coordination in the control of deglutiyion.

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