1. Sensorimotor Neurophysiology of Active Sensing
Overview
Dr. Martha Flanders
Department of Neuroscience
University of Minnesota
Receptors and Spinal Cord
Dr. Steve I. Perlmutter Dept. of Physiology and Biophysics
Univ. Washington
Cerebral Cortex
Dr. Stephen I. Helms Tillery Harrington Dept. of Bioengineering
Arizona State University

2. 6 Layers 80% of neurons are excitatory pyramidal 1 Million Columns
Overview cortex
Schiebel et al. 1974
6 Layers
80% of neurons are
excitatory pyramidal
1 Million Columns
0.5 mm wide
processing modules
Receptive fields
Movement fields
Population Coding
Sparse Coding
Brodal 1981 (after Brodmann and Vogt) Golgi stain - Nissl stain - Myelin stain

3. Subcortical structures thalamus brainstem midbrain, pons medulla
Overview dorsal column nuclei, cerebellum, thalamus and cortex
thalamus
somatosensory
cortex
Cortical sheet
gray matter (neurons)
white matter (axons)
Subcortical structures
thalamus
brainstem
midbrain, pons
medulla
dorsal column nuclei
cerebellum
Spinal cord 
brainstem
(cerebellum)
Roberts and Hanaway 1970

4. Axons – more superficial Dorsal - sensory Ventral – motor
Overview receptors, spinal cord
Neurons – deep
Axons – more superficial
Dorsal - sensory
Ventral – motor
7 – Intermediate Zone
interneurons
8-10 – motor neuron cells
axons exit via ventral root
Dorsal Root
incoming sensory
information
Haines 1987
Iggo and Muir 1969

5. A) Input (motor error) = target state – current state
Overview efference copy
A) Input (motor error) =
target state – current state
Brain learns mapping from
A to B by comparing
efference copy to
sensory feedback
Comparison operations
occur at many levels
Somatosensory feeback
(tactile and proprioceptive)
can be used to continuously
guide an ongoing
< movement B A
target
state
motor
command
muscle activity
force
movement
efference
copy
current
state
sensory feedback
cortical
subcortical
spinal
target
state
efference
copy
motor
output
current
state
somatosensory feedback

6. Examples of Comparison
Overview neural comparison and cancellation
Corinne
Examples of Comparison
Sound localization in
barn owl brainstem
Primary afferent
depolarization in primate
spinal cord
A. Comparison
left
ear
Right
Mid
Left
right
ear
B. Cancellation
sensory input
efference copy
PAD
motor command
motor output

7. in electric fish brainstem
Overview neural comparison and cancellation
Heiligenberg 1973
A. Spinal Cord
muscle spindle
tendon organ
cutaneous
PAD
Object Localization
in electric fish brainstem
Primary afferent
depolarization in primate
A. spinal cord
B. brainstem?
dorsal root
ganglion
peripheral
sensory afferents
dorsal horn
spinal cord
B. Brain
efference copy
sensory input
inhibition
cerebral
cortex
motor command
motor output
dorsal column
nuclei - medulla

8. Research questions about
Overview neural feature extraction and extrapolation
A. Extraction
(*a)
(*b)
(*c)
B. Extrapolation
(*d)
(*e)
(*f)
Time (ms)
Time (ms)
Research questions about
neural mechanism in primate somatosensory cortex
SFA
STD