Analysis of the neural circuits underlying crawling in the leech

SCHNEIDER, ELISA; SZCZUPAK, LIDIA

Huerta Grande, Córdoba

Congreso; XXVII Reunión Annual de la Sociedad Argentina de Investigación en Neurociencias; 2012

Sociedad Argentina de Investigación en Neurociencias

@font-face { font-family: "Times New Roman"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }table.MsoNormalTable { font-size: 10pt; font-family: "Times New Roman"; }span.msoIns { color: blue; }div.Section1 { page: Section1; } Crawling is a locomotive behavior that the leech undertakes in shallow water and results from alternation between shortening and extension of the body. These movements are achieved by contraction and relaxation of longitudinal and circular muscles. The dorsal excitor 3 (DE-3) motoneuron (MN) and the circular ventral (CV) MN innervate these muscles, respectively. The network underlying crawling is poorly understood. The goal of the present project is to study its structure. We aim at understanding the motor pattern from cellular to network levels. Crawling can be induced in the isolated nerve cord using dopamime. The DE-3 MN activity is recorded extracellularly in the DP nerve and CV MN activity through intracellular recordings. The NS cell is a nonspiking neuron present in each midbody ganglion that is electrically coupled to every MN. Previous results have shown that the NS oscillates in phase with the motor pattern during crawling. Hyperpolarizing the NS neuron membrane potential slows down crawling and decreases the MN firing frequency. This result suggests that the MNs are part of the CPG because the inhibition of these cells not only decreases the firing frequency of the MNs but also slows dawn the rhythm of the motor pattern. We have observed that manipulations of CV membrane potential affect the motor pattern indicating that this MN is part of the CPG of crawling.