the intrinsic function of a motor system – from ion channels to networks and behavior
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The intrinsic function of a motor system – from ion channels to networks and behavior. S. Grillner, L. Cangiano, G.-Y. Hu, R. Thompson, R. Hill, P. Wallén. 3 types of motion. Propulsive movements Leg movements, wing movements, ondulatory trunk movements Postural motor system - PowerPoint PPT PresentationTRANSCRIPT
The intrinsic function of a motor system – from ion channels to
networks and behavior
S. Grillner, L. Cangiano, G.-Y. Hu, R. Thompson, R. Hill, P. Wallén
3 types of motion
• Propulsive movements– Leg movements, wing movements, ondulatory
trunk movements
• Postural motor system– Maintain body orientation
• Goal directed movements– Visuomotor coordination
Motor System overview
Part of major interest in thispaper
Oscillatory patterns in propulsive movements
The lamprey model
Forebrain control
• Direct projections from olfactory bulb and optic nerve into ventral thalamus• Basal ganglia control the activity of v. th. by GABAergic inputs (Similar function as in mammals. e.g. MPTP)• Reticulospinal neurons activate the spinal cord locomotor activity
Lamprey brainsteam-spinal cord preparation (in vitro)
Can be maintained in vitro over several days at T=4-7°C
Locomotion can be elicited bystimulation in the brainsteam or by administration of agonists of excitatory amino acids.Spinal cord networks producethe motor pattern. (Ondulations at 0.2-10 Hz)
Brainsteam-spinal cord circuitry
Connectivity is critical for producing the motor pattern.
Goal: isolate the circuitry in the spinal cord and see how it works on a detailed level.
Importance of membrane properties
sAHP regulates the duration of burstsdue to Ca-concentration in the cell Kca-ChannelsCa enters also if the neuron is notspiking (NMDA, LVA-Ca)
A whole series of mechanismsregulate the duration of bursts in the spinal cord pattern generator
Calcium Imaging in dendrites
The calcium signal correlates with the spiking of neurons in the ipsilateral ventral root.
Modulatory effect of metabotropic receptors
Implement the findings in amodel
Questions and next steps
• What is the influence of using T=4°C?
• Why are there stretch receptors, when the model works fine without?
• Include control mechanisms from brain: e.g. how to swim a curve.
• Can all metabotropic effects be included? These are the „interesting“ mechanisms.