Computational neuroethology: linking neurons, networks and behavior

1
Computational neuroethologylinking neurons,
networks and behavior

• Mark E. Nelson
• Beckman Institute
• Univ. of Illinois, Urbana-Champaign

2
TALK OUTLINE

• Multiscale modeling in computational
  neuroethology
• Model system - weakly electric fish
• Modeling strategies
• Level I Behavior
• Level II Sensory physics
• Level III Single neurons
• Level IV Local networks
• Summary

3
MultiscaleOrganization of theNervous System
Organism
1 m
Brain/CNS
10 cm
Brain maps
1 cm
Networks
1 mm
Neurons
100 mm
Synapses
1 mm
Molecules
1 Å
Churchland Sejnowski 1988
Delcomyn 1998
4
NeuroethologyNeural Basis of Behavior
Organism
Neural Integration
Brain
Sensory Processing
Motor Control
Body
Sensors
Effectors
Environment
Delcomyn 1998
5
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?

6
BACKGROUNDWeakly Electric Fish
7
Distribution of Electric Fish
8
Black ghost knifefish (Apteronotus albifrons)
9
Electroreceptors 15,000 tuberous
electroreceptor organs1 nerve fiber per
electroreceptor organup to 1000 spikes/s per
nerve fiber
mechano
MacIver, from Carr et al., 1982
10
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

11
Self-generated Electric Field
12
Principle of active electrolocation
13
Prey-capture Behavior
Daphnia magna (water flea)
1 mm
14
BEHAVIORElectrosensory-mediatedPrey capture
behavior
15
Prey-capture video analysis
16
Prey capture behavior
17
Fish Body Model
18
Motion capture software
Motion capturesoftware
19
MOVIE prey capture behavior
20
Rapid reversal marks putative time-of-detection
Velocity Profile (N116)
Zero-crossingin accelerationis used
asdetection time
Acceleration Profile (N116)
21
Distribution of detection points
Front view
Side view
22
Active motor strategies Dorsal roll toward prey
23
NeuroethologyNeural Basis of Behavior
Organism
Neural Integration
Brain
Sensory Processing
Motor Control
Body
Sensors
Effectors
Environment
Delcomyn 1998
24
PHYSICSofelectrosensory image formation
25
Electrosensory Image Reconstruction
26
Estimating Daphnia signal strength

• Voltage perturbation at skin Df

prey volume
electrical contrast
fish E-field at prey
distance from prey to receptor
THIS FORMULA CAN BE USED TO COMPUTE THE SIGNAL AT
EVERY POINT ON THE BODY SURFACE
27
(No Transcript)
28
Reconstructed Electrosensory Image (Df)
29
Electrosensory Images
30
ELECTROPHYSIOLOGYofprimary sensory afferents
31
Electroreceptors 15,000 tuberous
electroreceptor organs1 nerve fiber per
electroreceptor organ
mechano
MacIver, from Carr et al., 1982
32
Neural coding inelectrosensory afferent fibers
33
Probability coding(P-type) afferent spike trains
?Phead? 0.337
Phead 0.333
Phead 0.333
00010101100101010011001010000101001010
34
Model of primary afferents
Brandman Nelson Neural Comp. 14, 1575-1597
(2002)
35
ELECTROPHYSIOLOGYofCNS electrosensory neurons
36
ELL Circuitry
37
ELL histology
38
Compartmental Modeling
39
Compartmental Modeling
Hodgkin-Huxley Model for voltage-dependent
conductances
40
Compartmental Modeling
Hodgkin-Huxley Model for voltage-dependent
conductances
41
ELL pyramidal cell
42
ELECTROPHYSIOLOGYofelectrosensory networks
43
Central Processing in the ELL
44
Spatiotemporal processing in 3 parallel ELL maps
Centromedial map Space small RFs Time low-pass
temporal integration
Centrolateral map Space med. RFs Time band-pass
Primary Electrosensory Afferents
both
spatial integration
Lateral map Space large RFs Time high-pass
45
Multiresolutionfiltering in the CNS
46
NeuroethologyNeural Basis of Behavior
Organism
Neural Integration
Brain
Sensory Processing
Motor Control
Body
Sensors
Effectors
Environment
Delcomyn 1998
47
Acknowledgements

• Malcolm MacIver
• Noura Sharabash
• Relly Brandman
• Jozien Goense
• Rama Ratnam
• Rüdiger Krahe
• Ling Chen
• Kevin Christie
• Jonathan House
• NIMH and NSF