Motor systems1 ACTIVE SENSING Lecture 5: Motor systems IV.

Motor systemsMotor systems 11

ACTIVE SENSINGACTIVE SENSING

Lecture 5: Motor systems IVLecture 5: Motor systems IV


Motor control of the vibrissal systemMotor control of the vibrissal system

Whisker movement (whisking control)

Touch (perceptual control)



Whisker movement (whisking control)

Touch (perceptual control)

1 2 3 4 5 6 7

A

B

C

D

E

Row D

Arc

1



Dorfl J, 1985, J Anat 142:173-184

Horizontal cut through row C

1mm


Motor control of the vibrissal systemMotor control of the vibrissal systemIntrinsic muscles

Dorfl J, 1982, J Anat 135:147-154

0.5 mm



Dorfl J, 1982, J Anat 135:147-154


Motor control of the vibrissal systemMotor control of the vibrissal systemExtrinsic muscles

Dorfl J, 1982, J Anat 135:147-154



Dorfl J, 1982, J Anat 135:147-154


Motor control of the vibrissal systemMotor control of the vibrissal systemInnervation

Dorfl J, 1985, J Anat 142:173-184



Innervation - motor

Dorfl J, 1985, J Anat 142:173-184



Innervation - motor

Dorfl J, 1985, J Anat 142:173-184

Row ERow C



Innervation - motor

Dorfl J, 1985, J Anat 142:173-184


Motor control of the vibrissal systemMotor control of the vibrissal systemCoordination of extrinsic and intrinsic muscles

Hill, Bermejo, Zeigler, Kleinfeld, unpublished


Motor control of the vibrissal systemMotor control of the vibrissal systemPad motion


Motor control of the vibrissal systemMotor control of the vibrissal systemPad and whisker motion



Innervation - sensory

Dorfl J, 1985, J Anat 142:173-184

•A row as a unit of processing



Innervation - sensory

Dorfl J, 1985, J Anat 142:173-184


Follicle as a motor-sensory junctionFollicle as a motor-sensory junction•Motor control is an integral component of sensation•The sensory organ reports back details of self motion•Plus perturbations of this motion caused by the external world

Dorfl J, 1985, J Anat 142:173-184

=proprioception


Vibrissal proprioceptionVibrissal proprioception

•might contain muscle spindles •Connected to facial bones•might contain tendon organs

Extrinsic muscles

•No signs of muscle spindles •No bony connections•No joints, no tendons

Intrinsic muscles

How is whisker movement tracked by the brain?How is whisker movement tracked by the brain?


Vibrissal proprioceptionVibrissal proprioception

• Each follicle contains ~2000 receptors

• About 20% of them convey pure

proprioceptive information

• (Other 20% convey proprioceptive

information mixed with contact information)

• It is not yet clear what aspects of motion

they encode: ’’’other

• What is known is that they fire consistently

during whisker motion, regardless of

contacts with external objects


The spinal loop (stretch reflex)The spinal loop (stretch reflex)

Knee joint

Motor neuron

’’spindle

whisker

Motor neuron

W receptors

Sensory neuron

The brainstem loopThe brainstem loop


Contact loop

Proprioceptive loop

Proprioceptive loop

Skeletal systemVibrissal system


Whisking behavior – reflections of control loopsWhisking behavior – reflections of control loops


Contact loop

Proprioceptive loop Proprioceptive loop

Skeletal systemVibrissal system

Contact loop


Loop sign – effect of contextLoop sign – effect of context

Mitchinson, Martin, Grant, Prescott (2007) Proc R Soc Biol Sci

Positive(?) contact loopNegative contact loop


Loop sign – effect of contextLoop sign – effect of context

Mitchinson, Martin, Grant, Prescott (2007) Proc R Soc Biol Sci

Negative contact loop


Brainstem in a dishBrainstem in a dish

Nguyen & Kleinfeld, Neuron 2004


Anesthetized brainstem loop is positiveAnesthetized brainstem loop is positive

Nguyen & Kleinfeld, Neuron 2004


End of Lecture 5End of Lecture 5

Motor systems1 ACTIVE SENSING Lecture 5: Motor systems IV.

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