Lecture 3:Lecture 3:

Sensory systems involved in Sensory systems involved in Motor ControlMotor Control

Why do we need senses?Why do we need senses?

Provide information for reflexive Provide information for reflexive movement at the spinal cord level.movement at the spinal cord level.

Voluntary movement:Voluntary movement:Initiate, adjust and terminate the output Initiate, adjust and terminate the output of movement.of movement.

Sensory systemsSensory systems

VisualVisual Audio/vestibularAudio/vestibular ProprioceptionProprioception - Muscle spindle- Muscle spindle - GTO- GTO - Joint receptors- Joint receptors - Cutaneous (touch)- Cutaneous (touch)

VisionVision

The eye...The eye...

The eyeThe eye RetinaRetina PhotoreceptorsPhotoreceptors Rods - night visionRods - night vision Cones - daylight, color visionCones - daylight, color vision FoveaFovea

Sensory differentiation is a key to sensory Sensory differentiation is a key to sensory processing (e.g. color blind).processing (e.g. color blind).

Cone Rod

Vision...Vision...

External-External-environmentenvironment

Identify objects in Identify objects in space.space.

Determine their Determine their motion/movementmotion/movement

Internal-our bodyInternal-our body

Where is our Where is our body in space in body in space in relation to our relation to our body and motion.body and motion.

Vestibular systemVestibular system

Components:Components:

Semicircular canalsSemicircular canals Utricle and SacculeUtricle and Saccule Otolith organOtolith organ

Hair cells generate response due to Hair cells generate response due to the movement of fluid.the movement of fluid.

The vestibular system The vestibular system Sensitive to:Sensitive to: The position of the head in space and The position of the head in space and

sudden changes in the movement of the sudden changes in the movement of the head.head.

Stabilizes the eyes and maintains postural Stabilizes the eyes and maintains postural stability during stance and walking.stability during stance and walking.

Abnormalities cause: dizziness, unsteadiness Abnormalities cause: dizziness, unsteadiness problems focusing our eyes and maintaining problems focusing our eyes and maintaining balance.balance.

ProprioceptionProprioception Muscle spindleMuscle spindle GTOGTO JointJoint CutanousCutanous

-Provide information of location and -Provide information of location and movement with relation of parts of the movement with relation of parts of the body to other parts of the body.body to other parts of the body.-Provide information to motor control.-Provide information to motor control.

Muscle spindleMuscle spindle

Located in the muscle belly of a skeletal Located in the muscle belly of a skeletal musclemuscle

Sensitive to stretchSensitive to stretch Highest spindle density in the eye, hand Highest spindle density in the eye, hand

and neck muscles (involved in eye-hand and neck muscles (involved in eye-hand coordination).coordination).

Golgi Tendon Organ - GTOGolgi Tendon Organ - GTO

Sensitive to tensionSensitive to tension Sensitive to small amounts of Sensitive to small amounts of

tensiontension

Joint receptorsJoint receptors

Located in joint capsulesLocated in joint capsules Sensitive to joint angles - provide Sensitive to joint angles - provide

danger signalsdanger signals

CutaneousCutaneous

Mechanoreceptors - mechanical stimuliMechanoreceptors - mechanical stimuli Thermoreceptors - temp.Thermoreceptors - temp. Nociceptors - potential damage to the Nociceptors - potential damage to the

skin.skin.

Cutaneous info. gives rise to reflex Cutaneous info. gives rise to reflex movements e.g. bottom of the foot.movements e.g. bottom of the foot.

Characteristics of the sensory Characteristics of the sensory informationinformation Where is the stimulus?Where is the stimulus? What is the intensity?What is the intensity? What is the duration?What is the duration?

Transmission to other systemsTransmission to other systems