The Croonian lectures on some points connected with sleep, sleeplessness, and hypnotics / by John Buckley Bradbury.

  • Bradbury, J. B. (John Buckley), 1841-1930.
Date:
1899
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Licence: Public Domain Mark

Credit: The Croonian lectures on some points connected with sleep, sleeplessness, and hypnotics / by John Buckley Bradbury. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    processes of the neuroglial cells contracted or expanded and he suggests that a function of these cells is to act as an isolating medium between the neurons. During sleep the neuroglial processes are introduced between the nerve rami- fications and the cells or their protoplasmic processes, in consequence of which the passage of impulses is prevented or hindered. Apart from the seat of operation, Ram6n y Cajal's theory diEEers from Duval's in that the pro- cesses (neuroglial in the case of Ram6n y Cajal) are expanded when the brain is at rest and are contracted when in action. The contraction is usually automatic, but may be brought about by the action of the will. I do not, however, propose to follow Ram6n y Cajal in his explanation of psychological phenomena on this theory, especially as his observations have not been confirmed by more recent investigators. His theory seems to me to endow the neuroglial cells with more nervous activity than they are capable of and to allot to them a function which, from their position and structure, I venture to think cannot be main- tained. Moreover, if we accept the network theory of Boll, Hill, and others, or Berkley's or Lugaro's modification of the usually accepted view, this explanation loses nearly all its ^Before leaving the histological theories of sleep I will briefly refer to a view recently advanced by Gotch to explain the conditions of hypnotism. He goes further than Duval m attributing a major influence to the periphery of the neuron, for he believes that the gaps between the terminations of the adjoining dendritic processes are of primary importance in the transmission of nerve impulses. These gaps determine whether an impulse shall pass or not; once it has passed Gotch believes nothing can hinder its further course, ihe gaps are capable of variation; in fact, he states that the whole of modern physiology is inexplicable except on the supposition that the gaps are susceptible of altera- tion What this alteration is we do not know; the gap consists of living tissue and, like all living structures, is constantly undergoing molecular change. The resistance of the gap varies with diflEerent conditions ; thus the action of the higher nerve centres increases the resistance; the force of habit or practice diminishes it; constant attention leads to fatigue-changes in the intercalated material, aiid the forcing of the gaps is then a concomitant of the mental mood of volitional attention. Although this theory is primarily advanced to explain hypnotic phenomena it is evident that a similar explanation might be advanced to account for sleep. It does not seem quite clear to me whether the resistance is due to a molecular rearrangement ot tne intercalated material or to an increase of its amount between the dendrites. If the latter, as is suggested in one place, the conditions simulate those advanced by Rabl-Ruckharri, L6pine, and Duval. Gotch's theory differs from theirs in attributing a greater influence to the gaps than to the proto- plasmic processes. Like its allies it must consequently stand