Behavioral transitions modulate hippocampal electroencephalogram correlates of open field behavior in the rat: Support for a sensorimotor function of hippocampal rhythmical synchronous activity

Abstract

A clear relationship exists between moment-to-moment behavioural elements and hippocampal Rhythmical Synchronous Activity (RSA, theta rhythm). However, behavioural elements are not isolated events, but are part of behavioural sequences in a context of behavioural activity. By concurrently monitoring open field behaviour and hippocampal EEG, EEG correlates of open field behaviour in relation to preceding and following behaviour were studied in Sprague-Dawley rats to determine whether the behavioural context influences EEG correlates of behaviour. Results show that preceding and subsequent behavioural patterns influenced the spectral power correlates of behaviour. RSA power was increased when a 'type 1 behaviour' (voluntary movement) preceded the behaviour compared to when a 'type 2 behaviour' (automatic movement, awake immobility) preceded it. The modulating effect of behavioural transitions was shown for several types of behaviours, and systematic modulation of hippocampal EEG correlates of behaviour was demonstrated. The present report shows that the strong and systematic relationship between hippocampal RSA and behaviour is modulated by the behavioural-sequential context. Thus, in addition to the well-established relationship between RSA and motor activity, a second non-motor process seems to contribute to hippocampal RSA. A likely candidate is a sensory process, which is in accordance with theories on the sensory-motor function of hippocampal RSA.