EXSS 380- Sensory Contributions to Motor Control (pt. 1)

what is also known as a closed loop?

feedback systems

what is a feedback system?

sensory input (feedback) processed to generate or refine movement commands

generalize a closed loop system

CNS changes output based on sensory input

what is also known as an open loop system?

feedforward system

what is a feedforward system?

CNS provides output independent of sensory input or movement outcomes

what must the CNS have knowledge of before completing a feedforward action?

• status of system

• surroundings

what is available but not utilized during activation of an open loop system?

feedback

what is purposeful human movement governed by?

inter-related feedforward and feedback control loops

what is essential for the initiation and regulation of movement?

sensory information from internal and external environments

what are common forms of sensory information we see?

• state of the environment

• state of the body (neural and mechanical)

• state of body with respect to the environment

what are the three types of proprioceptive information we see?

• joint position sense

• kinesthesia

• force sense

what is joint position sense?

spatial orientation of body segments

what is kinesthesia?

sensation of joint motion

what is force sense?

sense of how much force is being produced

what are the five sources of sensory information available to inform the CNS of movement characteristics?

• vision

• audition

• tenomuscular receptors

• articular receptors

• cutaneous receptors

what provides the most important sensory information regarding external environment?

vision

what does vision do for us?

has a role in planning and executing movement

what can vision tell us?

• target identification

• obstacle identification

• essential for error correction

is vision essential for movement?

no

what is greatly impaired with vision?

accuracy

what sees deficits with no vision?

postural control

what refines motor control, and aids in preparing the neuromuscular system for activity?

audition

what is included in audition?

• speech

• proper use of electronics

• terrain during gait

• object integrity

is audition required for the production of voluntary movement?

no

what is sensitive to muscle length?

II muscle spindle

what is sensitive to changes in muscle length?

Ia muscle spindle

what do muscle spindles tell us indirectly?

joint position sense and kinesthesia

what are muscle spindles efferently innervated by?

gamma and beta motor neurons

what does contraction do for muscle spindles?

lengthens equatorial region, exciting Ia afferent

what does contraction of muscle spindles do?

• alpha-gamma coactivation

• primes muscle spindles to detect changes

are muscle spindles perfect?

no

what distorts muscle spindles?

vibration

what is sensitive to muscle tension?

Golgi tendon organ

what do golgi tendon organs indicate?

muscle activation status

why is there limited usefulness for the golgi tendon organs?

potential for multiple levels of sensory input at same joint position

what are sensitive to joint displacement, joint tension, and compression?

articular receptors

where are articular receptors most stimulated?

near extremes of ROM

why do articular receptors have limited usefulness?

• not as active in normal ranges

• differing activity at same joint angle for differing levels of contraction

what are sensitive to touch, pressure, pain, and temperature?

cutaneous receptors

what are cutaneous receptors essential for?

precision control of grip force

what do pressure receptors contribute to?

joint position sense and kinesthesia

why do braces and neoprene sleeves aid in motion?

they stimulate pressure receptors, which then bring more neural attention to that joint

why is sensory information relevant to proprioception and kinesthesia insufficient?

• redundancy of sensory information

• ensemble coding

what is ensemble coding?

CNS combines and integrates various sources of sensory input into a single stream (ensemble) to resolve ambiguity

generalize sensory info for long-duration movements

online (real-time) monitoring

generalize sensory info for rapid movement

goal oriented feedback

what requires considerable time for long duration movements?

error analysis and correction

how is long duration movement typically ascribed

tracking movements