sensorimotor system Flashcards
principles of sensorimotor function
association cortex
secondary motor cortex
primary motor cortex
Brain stem motor nuclei
spinal motor circuit
to the bottom-up
complete model of the sensory-motor system
association cortex
secondary motor cortex
basal ganglia/ PMC/ cerebellu
BSMN
SMC
sensory feedback
our sensory systems monitor the bodies responses and feed that information back into the sensorimotor circuit
in most cases such sensory feedback is involved directing the continuation of responses
except with
ballistic responses (brif,all or none,high-speed movment
central sensorimotor program theory
1- the lower levels of the sensorimotor system hierarchy possess ‘‘sensorimotor programs’‘,and those programs represent particular patterns of activity
2.a particular complex movment is produced by activating the appropriate combination of these programs (cut onion)
3.once a particular level of the sensorimotor hierchy is activated,it is capable of operating on the basis of sensory feedback without direct control by higher levels
motor equivilant
most movment can be carried out in a variety of different ways
can produece same movments with differents parts of your body
if you can do this means that that activity program can be found in the high programs of the sensory motor system hierchy
practice can create and/or modify sensorimotor programs
most theories talk of two sorts of processes that influence the learning of sensory motor programs
1:response chunking
2;shifiting control to lower levels
- response chuncking
means that with practice we carry motor programs as chuncks rather than individual units
dont have to think about in between movments
chuncks can be conbined with larger chuncks
2.shifting control to lower levels
has two advantages
- freezup hiegher levels of the sensory motor system hierchy to deal with more obscure aspects of performence
-it also allows greater speed when performing actions
there are many cases of neuropsychological patients responding to stimuli that they are not consciously aware of
two major areas of sensorimotor association cortext
1-posterior pariential association cortext
2-Dorsalateral prefrontal association cortext
posterior pariential association cortext
intergreates information about the current position of your body parts with information about the position of external objects that u wish to interact with
the posterior pariental association cortext
recives many inputs from:
-visual system
-auditory system
-somatosensory system
sends outputs to:
-frontal eye field
-various secondery motor cortices
-dorsolateral prefrontal association system
study
when demaged
can produce a variety of sensorimotor deficits:including deficits in the perceptions and memory of spatial relationships,in accurate reaching and grasping ,in control of eye movment and in attetion
apraxia and contralateral neglect are two most triking consequences of demage in that area
Apraxia: a disorder of voluntary movment that is not attributal to a simple motor deficency
people with apraxia may not be able to:
- immitate gestures (especially menigless ones)
-performe of menigful gestures on conmmand
-real or pantomime use of tool and objects
-there is one domain that apraxic error seems to always happen
-imitation of meanigless gesture
symptoms are bilateral and languague production deficit are common
contralateral neglect
they do it better
if it appears first to their left
dersonalteral perfrontal association cortext
invoved in the evaluation of external stimuli and the initiation of voluntary reactions to those stimuli
recive inputs:
-posterior parential cortext
sends outputs
-frontol eyefield
-primary motor cortext
-varies secondary motor cortices
dorsonalateral prefrontal cortext
fire first when it antecipates a motor activity
decision to inimate a voluntary movment occurs in the dorsal prefrontal cortext but it depends on the posterial parential cortext
secondary motor cortext
are cortexts that recive input from association cortext, and sends outputs to primary motor cortext
the number of secondary motor areas have changed
electrical stimulation in secondary motor cortext
elicits complex movments (often bliateral)
recording in this area show
that neurons become active just prior to initiation of a voluntary movment
this region is invoveld with complex series of movements
in general
thought to be involved in the programming of specific patterns of movments after taking instructions from dersolateral prefrontal cortext
posterial parenta cortext (input)>Dorsalateral prefrontal cortext>secondary motor cortext
mirror neurons
neurons that fire either when the individual performs a particular movment or when they observe that movment performend by another individual
- primary motor cortext
each site in the primary cortext controls a muscle in the contraleteral part of the body,and each neuron produces movment of that body part in a particular direction
current view
what is importanat is not the direcetion but the endpoint
demage to primary motor cortext
smaller affect you might expect:
large lensions may disrupt a persons’ability to move one body part independently of others, may reduce speed,accuracy and force of movment
cerebellum and basal ganglia
cerebellum
inputs:
-primary and secondary motor system
-information about descending motoe signals from the brain stem nuclei
-feedback from motor responses via the somatosensory and vestibular syste,
cerabellum
10% of the brain but has 50% the neurons of the brain
modulate sensory motor signals
cerebelum plays a very big impact in motor learning
demage to the cxerabellum
-loss of ability to precisely control the direction,force,velocity and ampituted of movment
-loss of ability to adapt patterns of motor output to changing conditions
-difficulties in mainstrining steady posture
-disturbance in balance and eye movment
-empiriment of learning motor sequence
-imperiments on measure of attetion and executive control,memory
current view of cerebellum functioning
1-cerebellum plays a fundamental role in timing.when demaged,motor commands and cognitive states are no longer appropretely selected and sequence
2-cerebellum is involved in sensorimotor imagery(active during real or fake imagery)
3-cerebellum is a learning machine
basal ganglia
complex nucli together
modulate motor output
also involves in a wide variety of cognitive function
and promotes new skill learning and helps the cortext consilidates new skill
parkisons affect this are of the brain
