Introducing the method of multielectrode arrays in the electrophysiological studies of the posterior hypothalamus in vitro

Theta rhythm is the best synchronized EEG activity recorded from the mammalian brain. The generation of theta in the limbic structures depends on activation of the ascending brainstem-hippocampal synchronizing pathway. One of the main structures of this pathway is the posterior hypothalamic area (PHa) which most probably modulates hippocampal theta frequency. Multielectrode Arrays (MEA) are a well-known tool in both in vivo and in vitro electrophysiology. Our new in vitro multi-recording setup is constructed using a glass multielectrode matrix consisting of 256 electrodes fitted on 10 square mm. Each electrode is 40 μm high, cone-shaped and represents a single field recording channel. During experiments, brain slices are constantly perfused with prewarmed and oxygenated cerebrospinal fluid which prevents the tissue from dying and allows direct administration of chemicals. Our previous in vitro experiments show that the PHa is capable of generating local theta rhythm in both in vitro and in vivo conditions. The aim of the current study was to introduce a new method of in vitro multisite recordings from posterior hypothalamic slices. Application of MEA recording method in the studies of PHa theta rhythm is discussed. Supported by NCN grant 2011/01/B/ N24/00373.