Evidence for Multiple Sources of Theta Generation in the Hippocampus and Related Structures
In earlier chapters, the topics dealt with have included the anatomical basis for hippocampo-cortical interaction, the general behavioural correlates of the rhythmic neural activity in the hippocampus which is envisaged to allow that interaction, and, in the last two chapters, the mechanisms of extrinsic control of that rhythm. The present chapter looks more deeply into the physical basis of the hippocampal theta rhythm itself. It is concerned with description of the profiles of electrical potentials which form the theta rhythms seen in different fields of the hippocampus and related structures, and in the different preparations that have been used. The primary data to be considered are, of course, the theta potentials generated in the hippocampal complex itself. However, towards the end of this chapter the data available on theta rhythms outside this structure are also described. In addition, details of experiments in which lesions have been made in the hippocampal complex and their influence on theta rhythms are described, because these data are important in interpreting the EEG profiles. However, the interpretation itself, which is complicated, is left to Chapter 8.
KeywordsEntorhinal Cortex Null Point Theta Activity Theta Rhythm Stratum Radiatum
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