Hippocampal type 1 (movement-related) theta rhythm positively correlates with serotonergic activity.
To investigate the relationship between the hippocampal [symbol: see text] activity (or Rhythmical Slow Activity, RSA) and the hippocampal serotonergic activity during spontaneous behavior, simultaneous recordings of i) hippocampal EEG, ii) sleep-wake activity, and iii) hippocampal levels of the serotonin (5-HT) metabolite 5-hydroxyndolacetic acid (5-HIAA--measured by in vivo voltammetry and infrared telemetry) were performed. The results show that hippocampal type 1 RSA recorded during wakefulness and voluntary movements (such as walking), is positively correlated to hippocampal 5-HIAA levels. Since in the experimental conditions used in the study, 5-HIAA levels are a reliable index of 5-HT release, the results support the hypothesis that hippocampal type 1 RSA is generated by a serotonergic mechanism. In contrast, hippocampal type 2 RSA recorded during desynchronized sleep is negatively correlated with 5-HT release, suggesting a different neurochemical mechanism for its production. These results also show that, in the experimental condition of this study, hippocampal RSA power spectrum has a main peak frequency of 3.5 during wakefulness, and of 6.5 Hz during desynchronized sleep.
Gemma
C
C
Istituto di Fisiologia Umana II, Università degli Studi, Milano, Italy.
Imeri
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L
Mancia
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M
D000818:Animals; D002531:Cerebellum / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology*; D004576:Electromyography; D007839:Functional Laterality; D006624:Hippocampus / Q000502:physiology*; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008297:Male; D009474:Neurons / Q000502:physiology*; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D013826:Theta Rhythm
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid