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Grillo SA. 
“Studies on the effect of d-Lysergic acid diethylamide (LSD-25) and the dorsal hippocampus in the integration of sensory information by the brain”. 
Medicine Afrique Noire. 1976;23(7):425-427.
Certain drugs like amphetamine, mescaline, LSD-25 and chlopromazine are known to affect behavioral responses and mood in man & animal. The type of behavioral responses produced by some of these drugs are dependent on the dose administered at a time. For example, amphetamine when administered in small doses will induce an increased state of attentiveness whereas in large doses hallucination and distraction are produced. On the other hand, LSD-25 in very small doses (10 mcg/kg) will induce distraction and hallucination in man and animal. It has been suggested that the hallucination produced by LSD-25 could be due to excessive entrance of all types of sensory information into the brain and the heightened perception of non-significant stimuli (Key, 1965). Key (1964) had shown that the surface positive secondary response at the auditory cortex was directly correlated with attention in the cat. It was also shown that this wave fluctuated more with attention. Grillo (1967) reported the relationship between-surface positive secondary response (slow potential) at the auditory cortex and the slow wave (slow potential) in the mesencephalic reticular formation. He showed that a correlation exists between the activity of the slow wave in the mesencephalic reticular formation and the slow wave or the secondary response at the primary cortex. However, the slow potential of the mesencephalic reticular formation was found to be different in configuration and time sequence from that of the auditory cortex. He, therefore, suggested that the sensory information first reaching the mesencephalic reticular formation is not immediately made available to the cortex; rather a mechanism may exist within the mesencephalic reticular formation which first handles the.information and assesses it as to its significance before passing on to the cortex. Therefore the fluctuation observed on the cortex could be the manifestation of what had already taken place in the mesencephalic reticular formation. Hence the slow potential of the primary auditory cortex can be used as an indicator for the degree or state of attentiveness in an animal or human experiments. This has also been reported by other workers (Haider et al., 1964; Davis, 1964). The effect of hippocampal stimulation on the slow potential or the secondary potential of the primary auditory cortex during distraction has been reported by Grillo (1971). During distraction the slow response-was reduced in amplitude, however, hippocampal stimulation was found to counteract the effect of distraction on the amplitude of the slow response. If LSD-25 induces distraction as part of the mechanism of its action, then hippocampal stimulation will be expected to counteract the effect of LSD-25 on the amplitude of the slow response of the primary auditory cortex. The purpose of this work, therefore, is to find out the effect of hippocampal stimulation on the action of LSD-25 on the slow response of the primary auditory cortex. The results will be discussed in relation to one of the causes of mental illness.
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