HK 258 Ch 4 & 5

exteroceptive

info provided from outside the body, provides info to processing system about the state of the environment in which one’s body exists

proprioceptive

within body, provides info about state of body itself

extroceptive info sources

vision, hearing/audition

proprioceptive info sources

sensing movement in joints and muscles

vestibular apparatus

in inner ear and provides info related to head movements and body orientation - posture and balance control

joint receptors

in capsules of joints and give info about extreme positions of joints

muscle spindles

in belly of skeletal muscles, as muscle spindles change length they provide info about joint position and stretch info

golgi tendon organ

junction between skeletal muscle and its tendon, sensitive to muscle tension and regulates levels of force

cutaneous receptors

specialized detectors of pressure, temp, touch; haptic sense

closed loop control system

state desired goal, sensory info goes in and measures compared to goal, any difference represents error, error transmitted to executive to decide what action to take, executive sends command to an effector, stabilized and sends new info to executive, closed by sensory information

feed forward

info represents anticipated sensory consequences of the movement that should be received if the movement is correct, so that the error signal would be zero

comparator

holds onto anticipated states and computes difference between these and real states to find error which is info returned to executive

monosynaptic stretch reflex (M1)

stretch to tendon/muslce causes reflexive muscle contraction, low level in spinal cord, first fast but not strong reflex to book example

multisynaptic reflex (M2)

2nd burst of activity and is longer but stronger than first, several synapses involved, higher levels in cns, 2nd reaction to book example

dorsal stream

specialized for movement control, involves entire visual field (central and peripheral), operates nonconsciously, fine control outside of our awareness, ex = cycling on busy street

ventral stream

conscious identification of objects, primarily in center of visual field, degraded by dim lighting, ex = picking up different kinds of cups

optical array

visible features reflect rays of light, enter eyes at specific angles

optical flow

flow of light across retina, environment shifting relative to subject and changing info provided by optical array, provides numerous important kinds of info about movement through environment

tau

time to contact info, retinal image size divided by image’s rate of change in size, proportional to time remaining until contact, t derived from optical flow info and used by dorsal stream

M3

voluntary reaction time, increased flexibility and latency

generalized motor program

theory than can account for common observation that movements can be varied along certain dimensions; for example playing piano slower or faster without sacrificing rhythm

motor program

pre structured set of movement commands that define and shape the movement

open loop control

opposite of closed loop, has 2 parts (executive and effector), doesn’t have feedback and comparator mechanisms, begins with input about desired state given to executive whose task is to define what action needs to be taken, effective as long as things go as expected, inflexibile in face of unpredicted changes, occurs to allow motor system to organize a rapid action without having to rely on slow info processing

startle RT

startle response movements intitiated faster than voluntary response to stimulus, motor program made in advance of stimulus to respond, released voluntarily

deafferentation

severing animals afferent nerve bundles where they enter cord so CNS can’t receive info from some portion of periphary

sensory neuropathy

lost sensory feedback, able to perform well in environment as long as visual info is available, movement production does not require sensory info from responding limb, deafferentation supports idea movements can be organized centrally in motor programs

central pattern generator

central organization established in brainstem, brief triggering stimulus (comman neuron) produces rhythmic commands, occur even if deaferented, genetically defined activities

reflex reversal phenomenon

depending on where stimulus has been applied, alterations in reflex happen depending on where in step cycle it was (extension or flexion)

relative timing

specified in program process to generate skilled movement

storage problem

concerns capacity required for storing all of these seperate programs in memory and made instantly retrievable when needed

novelty problem

every motor action is novel meaning the system would need a separate program for every action, how could something new be based on something previously stored in memory