EN
BACKGROUND AND AIMS: Just recently we discovered a local theta rhythm in the posterior hypothalamic area (PHa) in in vitro and in vivo conditions. Theta rhythm which appeared in the PHa was produced independently of simultaneously occurring hippocampal formation theta. In the present study we analyse the correlation of local PHa cells discharges with carbachol induced theta field potentials. Specifically, we emphasise a novel type of theta related cells which we labelled “timing cells”. METHODS: Ninety experiments were conducted on the Wistar rat’s PHa slice preparation. The local theta field potential was induced with 75 μM carbachol. Glassrecording electrodes were positioned with use of micropositioner in different regions of PHa (mainly supramammillary nuclei). Single cell activity and local field potentials were recorded simultaneously with the same electrode with respect to the ground. RESULTS: Sixty nonrelated and more that 50 theta-related cells were recorded. Twelve of theta-related cells were recognized and labelled as “timing cells”. These cells discharge rhythmically in the frequency range of 5–8 Hz and can be phase locked with local field potentials which appeared in 1–3 s lasting theta epochs. CONCLUSION: Posterior hypothalamic theta “timing cells” are probably involved in mechanisms responsible for programing the frequency of local theta field potentials and hippocampal formation theta rhythm.