Topic 5: Motor control

Cortical motor control centers

Regions in the brain that coordinate and execute motor movements.

Basal ganglia

A group of structures that coordinate movement and motor control, involving both direct and indirect pathways. activates correct motor plan and inhibits others

Ataxia

A lack of coordinated muscle movements, often resulting in clumsy, unsteady motion. Damage to the cerebellum, tested with the finger to nose test

Dysarthria

A speech disorder resulting from uncoordinated muscle movement, commonly associated with cerebellar damage.

Direct pathway

The pathway in the basal ganglia that facilitates movement.

Indirect pathway

The pathway in the basal ganglia that inhibits competing movements.

Hyperkinesias

Involuntary, undesired movements often associated with basal ganglia disorders

Chorea

Uncontrollable, jerky movements, like twitching and abrupt jerking of the body.

Athetosis

Involuntary writhing contractions and twisting of the body into abnormal postures.

Parkinson's disease

A neurodegenerative disorder characterized by slowness of movement, tremors, and rigidity, DAMAGE OF THE DIRECT PATHWAY —> INDIRECT TOO ACTIVE

L-Dopa

A medication used to treat Parkinson's disease by replenishing dopamine levels. because it is a precursor to dopamine that can cross the Blood Brain Barrier and is converted into dopamine in the brain, helping to alleviate symptoms such as tremors and rigidity.

Huntington's disease

An inherited disorder leading to uncontrolled movements and cognitive decline, caused by a single gene defect, DECREASED INDIRECT pathway function, damage of the Striatum and affecting the ability to coordinate voluntary movements.

Cerebellum

A brain structure responsible for motor coordination, fine-tuning of movements, and motor learning, adapt motor programs when env changes ISPILATERAL

Motor learning

The process of improving the smoothness and accuracy of movements through practice.

Motor Hierarchy

A classification of how motor control is organized within the nervous system, from simple reflexes to complex voluntary movements.

Reflexes

Automatic, quick movements in response to stimuli that do not require cortical input (SPINAL)

Cortical Motor Control Centers

Regions of the brain responsible for planning and executing voluntary movements.

Central Pattern Generators

Neural circuits that produce rhythmic outputs, such as walking and chewing, without requiring cortical commands or external feedback.

Corticospinal Pathway

A major pathway that controls movements of the extremities, comprising lateral and medial tracts with contralateral effects.

Primary Motor Cortex (M1)

The area of the brain that sends signals to motor neurons for muscle movement, coordinating movements of multiple muscle groups (NOT INDIVIDUAL), neurons fire 5-100 msec before they move

Apraxia

A condition characterized by difficulty in motor planning and executing movements despite having normal muscle strength. caused by damage to the secondary motor cortex (can’t understand salute)

Mirror Neurons

Neurons that activate during the production and observation of actions, crucial for understanding others' actions.

Supplementary Motor Area (SMA)

A brain region involved in the initiation and coordination of self-initiated movements and complex sequences. intention —> actions, INTERNAL STIMULUS (playing an instrument)

Alien Hand Syndrome

A condition resulting from lesions in the SMA, where one hand acts autonomously, leading to bizarre and unintended actions, people are AWARE of their hand's actions but cannot control it consciously.

Prefrontal Cortex Role

Involvement in goal selection and response maintenance; damage can lead to disorganized or inappropriate actions.

Utilization Behavior

A phenomenon where patients engage in automatic actions that are inappropriate for the context, often without awareness.

Stroke

Caused by a lesion in PMC (M1), difficulty with intentional movement, no TOP DOWN CONTROL, contralateral, damage to cortical motor control centers

Polio (Poliomyelitis)

flaccid paralysis, weakeness or decay to lower motor (PNS), muscles can’t recieve signal

Secondary Motor cortex

anterior to the motor cortex, planning + control movements (Internal and external), consists of the premotor and supplemental motor area

Stereotyped movements

Somewhat complex, walking, vomiting, etc. are automatic, repetitive motions that occur without conscious thought, often regulated by brainstem and spinal mechanisms.

Movement of self-expression

cortex, higher level cognition that is fine tuned by the subcortex (typing, drinking, voluntary conscious movements)

Utilization of interneurons

All skeletal muscles need a motor neuron input

Knee jerk reflex

A simple, involuntary response that occurs when the knee tendon is tapped, causing a rapid contraction of the quadriceps muscle. MONOSYNAPTIC

Hemiplegia/Hemiplaresis

part of stroke, loss or weakness of voluntary movement in the CONTRALATERAL SIDE, primitive reflexes take over

Lateral Tract

One of the two main pathways of the corticospinal tract, primarily responsible for the control of fine motor movements in the limbs, having contralateral effects on muscle control.(TRUNK/TORSO)

Medial Tract

One of the two main pathways of the corticospinal tract, primarily responsible for the control of postural adjustments and gross motor movements, influencing muscles on the same side of the body.

Premotor cortex

EXTERNAL guided actions, conducts body in response to stimulus, neurons are a vocabulary based on whats available for movement planning and coordination. (red light = STOP)

Interior frontal cortex

Language with Broca’s area, manipulate airways to produce language = COMPLEX motor cortex

Frontal eye field

Area of the frontal cortex responsible for controlling eye movements, coordinating visual attention and saccades, attention and sensory integration

Topographic Correspondence

surface area for each body part is proportional to the part’s precision (hand more), placisity = areas can grow if you use it more

Parietal Cortex

related to motor, integrates sensory with somatosensory or vision to guide movements and spatial awareness.

Frith et al (1991)

PFC activation during decision-making tasks, highlighting its role in executive functions and cognitive control, more active in free choice tasks

Preservation

still repeating old motor activities even if it isn’t applicable anymore Behavioral response to stimuli despite irrelevance or change.

Utilization

A phenomenon where individuals instinctively engage in automatic and habitual actions in response to stimuli, even when not appropriate. THEY ARE NOT AWARE

Cerebellum Topography

Vermis/medial = movement (center) Far lateral = cognitive (speech), Flocculonodular = balance and eye movements.

Striatum

The largest component of the basal ganglia, involved in the regulation of movement and associated with cognitive functions and motivation. It includes the caudate nucleus and putamen. recieves the signals

Globus Pallidus (Pallidum)

A structure in the basal ganglia that acts as a major output nucleus, involved in the regulation of voluntary movement by inhibiting certain movements via its connections to the thalamus and other motor areas. The Globus Pallidus predominantly uses GABA as its neurotransmitter to exert inhibitory control over movement.

Substantia Nigra

A structure in the basal ganglia that is crucial for reward and movement. It contains dopamine-producing neurons that play a significant role in the modulation of motor control.

Subthalamic Nucleus

A small but important component of the basal ganglia network that modulates movement; it has an excitatory role and is involved in the indirect pathway for motor control.

Akinesia

A condition characterized by a loss or impairment of voluntary movement, CANT INITIATE, often seen in disorders such as Parkinson's disease, resulting in a decreased ability to initiate movement.

Bradykinesia

A slowness of movement that significantly affects the execution of voluntary actions, commonly seen in Parkinson's disease. It results in a decrease in speed and amplitude of motor activities. SLOW

Deep Brain Stimulation (DBS)

A neurosurgical procedure that involves implanting electrodes in specific brain regions to modulate abnormal activity, often used to treat movement disorders such as Parkinson's disease. Targets subthalamic nuclei so thalamus is less inhibited