ELECTROPHYSIOLOGICAL CORRELATES OF THE LIMBIC-MOTOR INTERACTIONS IN VARIOUS BEHAVIORAL STATES IN RATS

Depth electroencephalographic (EEG) activity was recorded from basolat eral amygdala (BLA), Ventral subiculum (VSB), n. accumbens (ACC) and s ubpallidal area (SPL) in freely moving rats, during locomotor tasks wi th various types of reinforcement in order to compare the strength of limbic-motor interactions in selected behavioral situations. For all E EG signals multichannel coherences (ordinary, multiple and partial) we re calculated using autoregression model. Partial coherences indicate the level of synchronization between two signals, thus they were assum ed to indicate the strength of direct connection between the structure s from which these signals have been recorded. The partial coherences were calculated for six selected frequency bands and the strength of c onnections within the BLA-VSB-ACC-SPL circuit was estimated for two di fferent behavioral situations and compared. It was found that the stre ngth of connections is sensitive to changes in both motor and emotiona l aspects of behavioral situation: the strength of BLA-VSB, VSB-ACC, a nd ACC-SPL depended on motor demands of behavioral task; these of BLA- VSB increased in the highest frequency bands in all emotionally engagi ng situations when compared with well trained locomotion; the strength of ACC-SPL increased in situations when automatic stereotyped motor b ehavior was induced by biologically important stimuli, while it decrea sed or did not change in the motor tasks demanding more precise and qu ickly adjustable movements. The results are discussed according to the motor-limbic integration model proposed by Mogenson and show the dyna mics of its connections in relation to the motivational-emotional cont ext of the task. (C) 1997 Elsevier Science B.V.