Computational neuroethology linking neurons networks and behavior Mark
Computational neuroethology: linking neurons, networks and behavior Mark E. Nelson Beckman Institute Univ. of Illinois, Urbana-Champaign
TALK OUTLINE Multiscale modeling in computational neuroethology Model system - weakly electric fish Modeling strategies n n Level I: III: IV: Summary Behavior Sensory physics Single neurons Local networks
Multiscale Organization of the Nervous System Delcomyn 1998 Organism 1 m Brain/CNS 10 cm Brain maps 1 cm Networks 1 mm Neurons 100 mm Synapses 1 mm Molecules 1Å Churchland & Sejnowski 1988
Neuroethology: Neural Basis of Behavior Organism Neural Integration Sensory Processing Brain Motor Control Body Sensors Effectors Environment Delcomyn 1998
Neuroethology of Electrolocation Big picture: What are the neural mechanisms and computational principles of active sensing? Small picture: How do weakly electric fish capture prey? What computations take place in the CNS during prey capture behavior?
BACKGROUND Weakly Electric Fish
Distribution of Electric Fish
Black ghost knifefish (Apteronotus albifrons)
Electroreceptors mechano ~15, 000 tuberous electroreceptor organs 1 nerve fiber per electroreceptor organ up to 1000 spikes/s per nerve fiber Mac. Iver, from Carr et al. , 1982
Ecology & Ethology of A. albifrons inhabits tropical freshwater rivers and streams in South America nocturnal; hunts at night for aquatic insect larvae and small crustaceans in turbid water uses electric sense for prey detection, navigation, social interactions ribbon fin propulsion – forward/reverse/hover
Self-generated Electric Field
Principle of active electrolocation
Prey-capture Behavior Daphnia magna (water flea) 1 mm
BEHAVIOR Electrosensory-mediated Prey capture behavior
Prey-capture video analysis
Prey capture behavior
Fish Body Model
Motion capture software
MOVIE: prey capture behavior
Rapid reversal marks putative time-of-detection Velocity Profile (N=116) Acceleration Profile (N=116) Zero-crossing in acceleration is used as detection time
Distribution of detection points Front view Side view
Active motor strategies: Dorsal roll toward prey
Neuroethology: Neural Basis of Behavior Organism Neural Integration Sensory Processing Brain Motor Control Body Sensors Effectors Environment Delcomyn 1998
PHYSICS of electrosensory image formation
Electrosensory Image Reconstruction
Estimating Daphnia signal strength Voltage perturbation at skin Df: fish E-field at prey volume electrical contrast distance from prey to receptor THIS FORMULA CAN BE USED TO COMPUTE THE SIGNAL AT EVERY POINT ON THE BODY SURFACE
Reconstructed Electrosensory Image (Df)
Electrosensory Images
ELECTROPHYSIOLOGY of primary sensory afferents
Electroreceptors mechano ~15, 000 tuberous electroreceptor organs 1 nerve fiber per electroreceptor organ Mac. Iver, from Carr et al. , 1982
Neural coding in electrosensory afferent fibers
Probability coding (P-type) afferent spike trains Phead = 0. 333 Phead = 0. 337 Phead = 0. 333 00010101100101010010100001010
Model of primary afferents Brandman & Nelson Neural Comp. 14, 1575 -1597 (2002)
ELECTROPHYSIOLOGY of CNS electrosensory neurons
ELL Circuitry
ELL histology
Compartmental Modeling
Compartmental Modeling Hodgkin-Huxley Model for voltage-dependent conductances
Compartmental Modeling Hodgkin-Huxley Model for voltage-dependent conductances
ELL pyramidal cell
ELECTROPHYSIOLOGY of electrosensory networks
Central Processing in the ELL
Primary Electrosensory Afferents te in m te p gr or at al io n Spatiotemporal processing in 3 parallel ELL maps Centromedial map Space: small RFs Time: low-pass Centrolateral map Space: med. RFs both Time: band-pass l ia n at tio sp gra te in Lateral map Space: large RFs Time: high-pass
Multiresolution filtering in the CNS
Neuroethology: Neural Basis of Behavior Organism Neural Integration Sensory Processing Brain Motor Control Body Sensors Effectors Environment Delcomyn 1998
Acknowledgements Malcolm Mac. Iver Noura Sharabash Relly Brandman Jozien Goense Rama Ratnam Rüdiger Krahe Ling Chen Kevin Christie Jonathan House NIMH and NSF
- Slides: 47