Download Computational Neuroethology

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
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Level
Level
Level
Level
I:
II:
III:
IV:
Summary
Behavior
Sensory physics
Single neurons
Local networks
Multiscale
Organization of the
Nervous System
Delcomyn 1998
Organism
1m
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
MacIver, 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
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
prey
volume
electrical contrast


E fish  r  3 1   prey /  water 
a

Df 
3
 1 2 / 

r
prey
water 

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
MacIver, 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
00010101100101010011001010000101001010
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
I ion  g Na m3h(Vm  ENa )  g K n 4 (Vm  EK )  g L (Vm  EL )
dm
  m (V )(1  m)   m (V )m
dt
dh
  h (V )(1  h)   h (V )h
dt
dn
  n (V )(1  n)   n (V )n
dt
ELL pyramidal cell
ELECTROPHYSIOLOGY
of
electrosensory networks
Central Processing in the ELL
Spatiotemporal processing in
3 parallel ELL maps
Centromedial map
Space: small RFs
Time: low-pass
Primary
Electrosensory
Afferents
Centrolateral map
Space: med. RFs
both Time: band-pass
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 MacIver
Noura Sharabash
Relly Brandman
Jozien Goense
Rama Ratnam
Rüdiger Krahe
Ling Chen
Kevin Christie
Jonathan House
NIMH and NSF