neuro exam 3

Prefrontal cortec (PFC)

• initated the long-term planning or cognitive ascpects of movement

• determines if some motor action is appropriate for the specific situation; aka weighs possible consequences of a movement

Posterior Parietal Cortex

integrates somatosensory and visual information to determine an appropriate motor response (ex. body positioning in an environment and not running into things)

premotor cortex

• envisions and maps out a complex motor sequence

• posterior of the frontal lobe

• damage = cannot put motor sequences together

Primary Motor Cortex (M1)

• required for deliberate, voluntary movements, movements made in response to a command

• influences motor neurons; stimulates contralaterally

• tonotopically organized

Cerebellum

the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance; ensures SMOOTH movements

lateral corticospinal tract (dorsolateral)

• controls contralateral distal limbs (arms, hands, legs, and feet)

• flow : crosses hemispheres at pyramidal decussation, down SC, contacts lower motor neurons in ventrsal horn, forms NMJ with muscles

Anterior corticospinal tract (ventromedial)

• controls trunk muscles and proximal limbs (ex. shoulders and pectorals)

• signaling from brain stem descends ipsilaterally but eventually crosses over in spinal cord

Basal Ganglia

• a set of subcortical structures that directs intentional movements, habit learning, and selection of actions

• mostly communicates within itself and motor cortex, not brain/SC

• damage: Parkinson's, Huntington's, Tourette's, OCD, addiction, etc.

Hyperkinesis

• Abnormally increased and sometimes uncontrollable activity or muscular movements (ex. Huntington's and Tourettes)

• aka dyskinesia'

• caused by damage to caudate putamen in basal ganglia

Hypokinesis

• loss of motor ability -> rigidity and bradykinesia

• caused by damage to basal ganglia

• result : parkinson's

Neuromuscular Junction (NMJ)

synapse between the axon terminal of a motor neuron and the section of the membrane of a muscle fiber with receptors for the acetylcholine released by the terminal

Agonist muscle

Main muscle responsible for movement. ex. bicep

antagonist muscle

The muscle opposite the agonist, which must relax and lengthen during contraction of the agonist. ex. tricep

Patient HM

• had severe seizures starting as a teen

• medial temporal lobe (MTL) was surgically removed including hippocampus and amygdala

• result: less seizure, anterograde amnesia

anterograde amnesia

unable to create new, discrete memories (ex. could not remember what he had just eaten for lunch right after finishing it)

retrograde amnesia

unable to successully retrieve memory from one’s past

procedural memory

memory needed to acquire new skills (ex. keeping pen still on a circular platform)

• part of implicit (unconscious) memory

explicit memory

• pieces of information that can be counsciously declared or stated explicitly

• “knowing what”

• aka declarative memories

• includes semantic and episodic memories

semantic memory

pieces of factual information (ex. earth is a planet)

• part of explicit memory

episodic memory

recollection of a discrete moment in a person’s life

• aka autobiographical memory

• ex. I ordered pizza last night

• part of explicit memory