Characterization of delta to theta transitions in the Hippocampus and Lateral Habenula following mechanic or optogenetical stimulation in anesthetized rats

DEMIAN GARCÍA VIOLINI; A. MOSQUEIRA; PATRICIO COLMEGNA; J. PIRIZ; M. BELLUSCIO; RICARDO S. SÁNCHEZ PEÑA

Mar del Plata

Congreso; XXX Congreso anual Sociedad Argentina de Investigación en Neurociencias; 2015

Sociedad Argentina de Investigación en Neurociencias

The use of intra-cerebral electrodes in animals may isolate neuronal activities from specificcerebral structures, obtaining electrophysiological signals which are denominated Local FieldPotentials (LFPs). Their oscillatory behavior covers a wide frequency range (0.1-300 Hz) thatcan be divided into several regions, according to particular cognitive states. For example, inthis work, we are focused on the transition between delta () and theta () rhythms which arein the 0.5-3 Hz and 4-8 Hz ranges, respectively [1].Another important point to analyze is the synchronization between different cerebral structures,which can be studied using these LFP activities by means of correlation analysis tools.In particular, here we explore the relation between the electrical activity in the hippocampus(HPC) and the lateral habenula (LHb). The HPC is a central cerebral structure related to theconceptual and spatial learning process, and its LFP oscillation in can be associated withexploratory activities and spatial information acquisition [2].On the other hand, the LHb is a small cerebral structure located below the hippocampus thathas been identified as a negative state decoder. In that way, the LHb activity increases whenthe consequences of a particular action are worst than expected [3], or in the presence ofintrinsically aversive stimuli [4]. Therefore, the activation of the LHb in a certain context issufficient for a negative response. Notably, the HPC and LHb LFPs can synchronize spontaneouslyin the range ([5, 6]).In order to study the transition mechanisms between and when the HPC and LHb arestimulated with different light signals, we carried out, as a starting point, experiments with nociceptivestimulus given by a tail pinch. From those experiments, we developed a quantitativemethod to identify the cognitive state of the HPC and LHb, measuring the correlation, energyand frequency content of their LFPs. Then, we employed that method to analyze experimentaldata obtained by optogenetic stimulation of the Diagonal Brocca Band (DBB) to characterizethe type of light pulse wave that effectively forces the ! transition in terms of its frequency,latency and duration