Task 5 - Senosrimotor s Flashcards
hierarchially organized
information flows from highest level (association cortex) to the lowest level of system (muscles)
efferent neurons
send impulses from the CNS to our limbs and organs
afferent neurons
receive information from sensory organs (eye, skin) and transmit this input to CNS
functional segregation
each neural structure performs a different functio
motor output guided by sensory output?
-Our body has mechanisms to monitor what is coming in (sensory) and what it goes out in response (motor).
Sensory feedback
feedback within sensory systems where info from sensory receptors is returned along afferent pathways -> so brain can monitor consequences of actions
Ballistic movements
Occur too fast to be modified by feedback
sensorimotor learning
when we first learn, each individual response is performed under conscious control -> after practice, responses become more organized and you do them without conscious regulation
electromyography EMG
electrical recording of muscle activity
fast twitch muscle fibers
- muscle that contracts rapidly but fatigues quickly
- quick movements like jumping ->contract and relax quickly
slow twitch muscle fibers
muscle fiber that contacts slowly and weaker but able to sustain contraction longer
-movements like walking
Sensorimotor association cortex
top of sensorimotor hierarchy and divided into two areas
- posterior parietal association cortex
- dorsolateral parietal association cortex
posterior parietal association cortex
directing behaviour by providing spatial information
- directing attention ->receives input from more than one sensory input (visual, auditory and somatosensory system)
- most of the output goes to the secondary (non-primary) motor cortex or to the dorsolateral prefrontal association cortex
what happens if we damage posterior parietal cortex?
a variety of deficits, deficts in the perception and memory of spatial relationships
- in accurate reaching and grasping
- in the control of eye movement
- attention
Aprexia
difficulty making specific movements when they are requested to do so, if they don’t think about it they are able to move
Contralateral neglect
Disturbance of ability to respond to stimuli on side of body opposite to side of brain lesion
Dorsolateral prefrontal association cortex
location: frontal cortex, anterior to precentral gyrus
- identify and respond to objects
- iINTERACTS with posterior parietal to initiate voluntary movements
- METAMEMORY (self-awareenss of memo)
Dorsolateral prefrontal a.c. input
receives info from posterior parietal cortex
Dorsolateral prefrontal a.c.
output
sends info to areas of secondary motor cortex
Dorsolateral neurons
send the info out
- their activation depends on location and characteristic pf objects and the combi of the two
- fire first in response
what happens if we damage dorsolateral prefrontal cortex
Confabulation : unable to distinguish are true memory from a false or inappropriate for cortext (bcs dorsolat is important for meta memory)
Secondary motor cortex
location: posterior part of frontal gyro
function: storage of programs of motor activity from past experience
- control of movement
primary direction of information flow
in sensory systems, information mainly flows up the hierarchy
; in the sensorimotor system, information mainly flows down
electrical stimulation of PPAC
causes patients to experience the intent to perform a particular action
what causes apraxia?
unilateral damage to the left posterior parietal lobe or its connections; would have difficulty making specific movements
what happens with contralateral neglect?
left side of their world down not exist. fail to appreciate that they have a problem
three major areas of secondary motor cortex
premotor, supplementary, and cingulate
supplementary motor area
wraps over the top of the frontal lobe and extends down its medial surface into its longitudinal fissue
Primary motor cortex
location: precentral gyrus of frontal lobe function : execution of body movements (hand and mouth)t
premotor cortex
runs in a strip from the supplementary motor area to the lateral fissure
cingulate motor areas
three small areas in the cortex of the cingulate gyrus
motor homunculus
motor cortex is organized in a somatotopic manner; according to a body map
damage to primary motor cortex
small lesions often have minimal effects; large lesions may disrupt a patient’s ability to move one body part independently of others
Mirrorneurons
neurons that fire when an individual performs a particular goal-directed hand movement or when she or he observes the same goal-directed movement performed by another; neural basis of learning by imitation
when are mirror neurons active
up to 50% of neurons in sensorimotor cortex are active when imagining or watches an action ; body does not move when mirror neurons fire because the overall level of activity is lower than needed
basal ganglia and cerebellum
interact at many levels of the sensorimotor hierarchy; coordinate and modulate; may permit maintenance of visually-guided responses despite cortical damage
cerebellum
- 10% of brain mass and 50% of brain neurons
- is organized stematically in lobes columns and layers
cerebellum involved in
timing, fine-tuning, and motor learning
basal ganglia
act as a filter, blocking plans that are inappropriate.
-Example – Inhibiting automatic, environment-triggered responses such as grasping food.
BASAL GANGLIA input
primary motor cortex
primary somatosensory cortex
substania nigra- dopamine
Basal ganglia output
Primary motor cortex
supplementary motor area
premotor cortex
damage to basal?
- Parkinson’s disease – Problems controlling speech, movement and posture.
- Huntington’s disease – Disorder in which nerve cells in certain parts of the brain waste away, degenerate.
- Wilson’s disease – Disorder causing too much copper in the body’s tissues.
- Dystonia – Muscle tone problems.
- Progressive supranuclear palsy – Movement disorder from damage to certain nerve cells in the brain.
- -»Mostly movement disorders
withdrawal reflex
- the contraction of a muscle when a painful stimulus is encountered
- NOT monosynaptic and it takes longer
- > does not go to the brain
1.Dorsolateral corticospinal tract
direct
contralateral
distal muscle -> finger tips, fine momvement
-towards the back and on the side
2.Dorsolateral corticorubrospinal tract
indirect
contralateral
rubro= stop at red nucleus
distal muscle -> finger tips, fine momvement
1.Ventromedial corticospinal tract
-direct pathway
-towards the belly and medial
Ipsilateral
-proximal muscles-> legs, arm, shoulders
2.Ventromedial cortico-brainstem-spinal tract
indirect -stops at the brainstem -towards the belly and medial Ipsilateral -proximal muscles-> legs, arm, shoulders
Tectum
receives auditory and visual info about spatial info
vestibular nucleus
receives info about balance from receptors of inner ear
reticular formation
contains motorprogams that regulate complex movements like walking swimming jumping
motor nuclei
controls muscle of face
similarity of the two pathways
- Both have two major tracts, 1.one whose axons descend directly to the spinal cord
2. another whose axons synapse in the brain stem on neurons that in turn descend to the spinal cord
sensorimotor spinal circuits
- lowest level -> hierarchy
- consisting of the spinal circuits and the muscles they control
- circuits are capable of independent functioning
motor unit
- also called moton neuron
- motor in the brain or spinal cord that transmits motor messages, stimulating a muscle or gland
motor end plate
- Acetylcholine, which is released by motor neurons at neuromuscular junctions
- > activates it on each muscle fiber and causes the muscle to contract.
Flexors
act to bend or flex a joint (=biceps)
Extensors
Act to straighten or extend a joint (=triceps)
Synergistic muscles
-Two muscles whose contraction produces the same movement
Antagonistic muscles
Two muscles that act in opposition (biceps – triceps).
Isometric contradiction
Activation of a muscle that increases the tension that it exerts on two bones without shortening and pulling them together
Dynamic contradiction
shortening the muscle and pulling it together
-muscle tension can be increased by increasing number of neurons in its motor pool that are firing
skeletal muscles
are attached to bones by tendons, and they produce all the movements of body parts in relation to each other
->voluntary control
smooth muscles
consists of narrow spindle-shaped cells with a single, centrally located nucleus
-not voluntary
