The modular nervous system – from intrinsic function of microcircuits to the control of action. Sten Grillner
Sten Grillner, Nobel Institute for Neurophysiology, Dept of Neuroscience, Karolinska Institutet, SE-171 77 Stockholm
The vertebrate brain controls a variety of motor patterns through dedicated networks like those controlling eye movements, expression of emotions, respirations and locomotion. These networks are to a large degree conserved throughout the vertebrate phylum. The neural mechanisms underlying the control of behaviour will be in focus, both biological background information and multi-scale modelling from the subcellular and synaptic level to the microcircuit, systems and behavioural levels. My presentation, based on the lamprey CNS, will address the intrinsic function of the adaptable networks that generate different motor patterns. The mechanism by which different motor programs are selected will be considered with special reference to the basal ganglia-habenula – experiments and modelling. Our recent findings establish that the structure and function of the basal ganglia have been conserved throughout vertebrate phylogeny. This applies to the input to striatum (cortex/pallium, thalamus, dopamine, 5-HT), the pallidal structures (GPi, substantia nigra reticulata (SNr), GPe and the subthalamic nucleus), and the effects of an MPTP induced dopamine denervation.
To simulate the basal ganglia – brainstem – spinal cord networks and the dopamine input controlling different motor patterns, we simulate these networks with an approximate number of model neurons corresponding to that observed biologically. The model neurons are of the detailed compartmental Hodgkin-Huxley type with detailed membrane properties including all subtypes of ion channels observed biologically and the transmitter receptors. Each model neuron is designed to be very close to its biological counterpart. The synaptic interaction is modelled as well as network properties.
References:
Grillner, S. (2006) Biological Pattern Generation: The Cellular and Computational Logic of Networks in Motion. Neuron 52; 751-766.
Kozlov, A., Huss, M., Lansner, A., Hellgren Kotaleski, J., Grillner, S., 2009 Simple cellular and network control principles govern complex patterns of motor behavior. PNAS 106, 20027-20032.
Stephenson-Jones, M., Samuelsson, E., Ericsson, J., Robertson, B., Grillner, S., 2011 Evolutionary conservation of the basal ganglia as a common vertebrate mechanism for action selection. Curr Biol 21, 1081-1091.
Stephenson-Jones, M., Floros, O., Robertson, B., Grillner, S., 2012 Evolutionary conservation of the habenular nuclei and their circuitry controlling the dopamine and 5-hydroxytryptophan (5-HT) systems. PNAS 109,164-73.
Keywords: modelling, basal ganglia, networks
