Sunday September 23, 2012 15:15 - 15:45 @ Rhodes 7 

Probing neural systems controlling locomotion

Abstract:

Brain functions are generated by activity in dedicated neural circuits. Understanding the function and operational mode of such circuits in the complex mammalian brain is fundamental for understanding the normal and the diseased brain. Locomotor behaviors, like walking, are selected and are initiated from supraspinal neural circuits and is modulated by sensory inputs. However, motor circuits in the spinal cord itself generate the actual timing and coordination of the rhythmic muscle activity.  These circuits are therefore at the center of generating the behavior. Excitatory neurotransmission is known to play a critical role in the generation of the locomotor rhythm and the drive in the spinal locomotor networks. Here, I will present data on the identification of excitatory networks in the mammalian spinal cord locomotor networks involved in rhythm generation and in left-right coordination. Using mouse genetic with optogenetic activation and inactivation of glutamatergic excitatory neurons in the spinal cord we show that such neurons in the cord are directly responsible for rhythm-generation.  Using a combined genetic, anatomical, electrophysiological and behavioral approach we define new molecular subpopulation of these excitatory neuron controlling rhythm-generation or left-right coordination. We also define the molecular identity of neural circuits that are necessary for left-right coordination and are recruited in a task dependent manner. Together our experiments provide insights to the principal mode of operation of a large-scale mammalian motor circuit.

Supported by ERC advanced grant, Söderbergs Foundation and the Swedish Research Council.