Week7 Flashcards
The cerebellum plays an important role in ____, while the basal ganglia play an important role in ____ .
timing; voluntary movements
Early symptoms of Huntington’s disease usually include
Jerky arm movements and body tremors
Proprioceptive system
Body awareness; location of your
body in space
Movement Hierarchy
Reflexes
Automated movements
Voluntary movements
Reflexes
triggered by a sesnory stimulus
little voluntary control, can be modulated
eye blink
Automated movements
Postural: combination of reflex and volition used to
maintain an upright position with respect to gravity;
e.g., vestibulospinal reflexes
** Rhythmic**: initiation and termination is voluntary,
but the actual movement is more stereotyped; e.g.,
walking, running, chewing
Voluntary movements
- CNS responsible
- improves by practice
- reflex and postural movements compensate for the
effects of the intended action
Muscle Structure
attached at origin and insertion
Muscles Fibers and Axons
- Each muscle fiber receives information from only one axon; but a single axon may innervate many muscle fibers
- A neuromuscular junction is a synapse between a motor neuron axon and a muscle fiber
Acetylcholine
always excites skeletal muscles to contract (no relax cue)
slow twitch
red
aerobic
Nonstrenuous activities
Proprioceptors
receptors that detect the position or movement of a part of the body
Muscle spindles(Proprioceptors)
Proprioceptors parallel to the muscle that respond to a stretch: cause a contraction of the muscle
* A stretch reflex occurs when muscle proprioceptors detect the stretch and tension of a muscle and send messages to the spinal cord to contract it
Golgi tendon organ
(Proprioceptors)
- responds to increases in muscle tension
- Located in the tendons at the opposite ends of the muscle
- Acts as a “brake” against excessively vigorous contraction by sending an impulse to the spinal cord where motor neurons are inhibited
The primary motor cortex (M1)
- Muscle control
- intention of a movement
- opposite side of the body(mostly)
Posterior parietal cortex;
position of the body
Damage to this area causes difficulty in coordinating visual stimuli with movement
- Important for planning movement
Premotor cortex
- preperation for movement
- Receives information about a target
- Integrates information about position and posture of the body;organizes the direction of the movement in space
- Supplementary motor cortex
Organizes rapid sequence of movements in a specific order; inhibitory if
necessary
- Active seconds before the movement - Active following an error in movement so you can inhibit the incorrect
movement the next time
PFC
Active during a delay before movement
- Stores sensory information relative to a movement
- Necessary for you to consider the probable outcomes
of a movement
not directly connected to the spinal cord
Antisaccade task
inhibit a saccade, a voluntary eye movement from one target to another
pfc and basal ganglia before seeing the moving stimulus
matures through adolescensce
From the Brain to the Spinal Cord
- Messages from the brain must reach the medulla
and spinal cord to control the muscles - Corticospinal tracts are paths from the cerebral
cortex to the spinal cord
Lateral Corticospinal Tract
axons from PMC,red nucleus to the spinal cord
- Controls movement in peripheral
areas (hands and feet)
- Red nucleus: a midbrain area with
output mainly to the arm muscles
* Axons extend from one side of the
brain to the opposite side of the
spinal cord, and control opposite
side of the body
Medial Corticospinal Tract
Reticular formation, midbrain tectum, and vestibular nucleus
* Vestibular nucleus is a brain area that receives information from the vestibular system
* The medial tract controls the muscles of the neck, shoulders,
and trunk - Responsible for bilateral movements like walking, turning, bending, standing up, and sitting down
The Cerebellum
balance-coordination
damage causes trouble in rapid movements(aim/timing)
clapping,speaking,writing
responds to unexpected sensory stimulus
attention(shifting it)
Purkinje Cells
Purkinje cells: flat parallel cells in sequential planes
Parallel fibers excite Purkinje cells
purkinje cells send inhibitory measseges to nuclei of the cerebellum
then sent to midbrain and the thalamus.
The Basal Ganglia
(IN-IN)
(direct- excitatory)
- Caudate nucleus-Putamen( receive input from cerebral c. and send to globus pallidus.
- Globus pallidus(connects to thalamus for pmc and pfc
- learning motor skills, organizing sequences of movement, “automatic” behaviors, and new habits
driving a car, playing the piano, sports
Parkinson’s Disease
(Damaged mitochondria)
- muscle tremors, rigidity, slow movements, masked face, posture/gait issues
- difficulty in initiating spontaneous
movement in the absence of stimuli to guide the
action
Huntington’s Disease
(chromosome 4)
- neurodegenerativea
- dominant genetic mutation
- toxic to thecaudate and putamen
- kaput basal ganglia
- chorea Overstimulation of the motor drive (opposite to PD!)
