Two Afferent Systems Control the Activation of the Neocortex and Hippocampus
Throughout most of the twentieth century, it was very widely believed that the pattern of slow wave potentials recorded from the neocortex (the electrocorticogram) or from the surface of the scalp (the electroencephalogram) is closely related to the level of consciousness. This concept is illustrated in Figure 4-1 taken from Penfield and Jasper’s 1954 book on “Epilepsy and the functional anatomy of the human brain”1. In general, high levels of consciousness or excitement were said to be correlated with relatively low voltage higher frequency (fast) potentials while sleep or unconsciousness were said to be correlated with higher voltage lower frequency (slow) potentials. I was skeptical about this, in part because of doubts about the validity of psychological interpretations of any cerebral events, and in part because certain well-established facts did not agree with the conventional theory. One of these facts was the discovery by A. Wikler in 1952 that atropine, a drug that blocks some of the effects of the neurotransmitter acetylcholine, produces an abundance of large amplitude slow wave activity in the electrocorticogram in dogs without producing behavioral sleep or coma.
KeywordsSlow Wave Hippocampal Activity Atropine Sulfate Hypothalamic Stimulation Midbrain Reticular Formation
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Notes on Chapter 4
- 1.Penfield, W., and Jasper, H. (1954). Epilepsy and the functional anatomy of the human brain. Boston: Little, Brown and Co.Google Scholar
- 2.I was not the first to see this phenomenon. Ron Harper once told me that he had observed the effect while working at McMaster University but it was not mentioned in his Ph.D. thesis. However, Ron later mentioned the effect in a single sentence, “If the animal moved, however (following treatment with atropine) the slow waves would disappear and reappear after the movement had been completed,” [Harper, R.M. (1973) Relationship of neuronal activity to EEG waves during sleep and wakefulness, In Phillips, M.I. (ed.) Brain unit activity during behavior Springfield, Illinois: Charles C. Thomas, 130–154].Google Scholar
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