Physiology II: Nervous system V - Cerebellum, Brain stem, and Sleep

Three functionally distinct parts of the cerebellum: …

vestibulocerebellum, spinocerebellum, cerebrocerebellum

…: Important in maintaining balance and control of eye movements (nystagmus)

vestibulocerebellum

…: enhances muscle tone and coordinates skilled, voluntary movements

spinocerebellum

The spinocerebellum is involved in … of muscle contractions to coordinate movements involving multiple joints

accurate timing

The spinocerebellum compares cortical commands to actual … of muscles and actual joint positions and corrects movements

current state

…: role in planning and initiating voluntary activity by providing input to cortical motor area and role in procedural memories

Cerebrocerebellum

Cerebellum and basal ganglia both … activity intiated by the motor cortex but do not affect efferent neurons (motorneurons) directly

monitor and adjust

Basal ganglia …

inhibit muscle tone

Cerebellum …

enhances muscle tone

Motor command arises from motor cortex but actual excution of activity is … by the subcortical regions

coordinated subconsciously

…: unsteadiness or incoordination of limbs, posture, and gait

ataxia

…: wide-based, unsteady “drunken sailor” gait

unsteady gait

…: rhythmic oscillating eye movements (more in vestibular system lecture)

Nystagmus

…: reduced muscle tone but no paralysis

hypotonia

…: inability to preform rapid altering movements smoothly

Dysdiadochokinesia

…: while executing intentional movements

Intentional tremor

…: past pointing (finger nose test)

Dysmetria

Cerebellar signs and symptoms: … (6)

Ataxia, nystagmus, hypotonia, dysdiadochokinesia, intention tremor, dysmetria

…: link between spinal cord and higher brain regions, all incoming and outgoing fibers between periphery and higher brain centers pass through here, most cranial nerves arise

Brain stem

The brain stem contains centers controlling: … (3)

cardiovascular, respiratory, digestive

The brainstem contributes to … reflexes

equilibrium and postural

…: housed within brainstem and hypothalamus

sleep

…: widespread, diffuse, network of neurons, receives incoming sensory input → ascending fibers carry signals upward to activate cortex and help direct attention

Reticular activating system

…: sensory innervation involved in smell

olfactory

…: sensory innervation involved in vision

optic

…: mainly motor innervation, eyeball and eyelid movement, pupil constriction, change of lens shape for near vision, proprioception

oculomotor

…: mainly motor, eyeball movement and proprioception

trochlear

…: mixed nerves, chewing, somatic sensations (tough, pressure, pain, and temperature) of the face and mouth

trigeminal

…: mixed innervation, eyeball movement, proprioception

abducens

…: mixed innervation, facial expression, secretion of saliva and tears, taste from front of tongue

facial

…: hearing, sense of equilibrium

vetibulocochlear

…: mixed innervation, swallowing, secretion of saliva, taste from posterior aspect of the tongue, somatic sensation of oral caity, blood pressure monitor

Glossopharyngeal

…: mixed function, efferent output for skeletal muscles of pharynx (throat) and larynx (voice box) and for smooth muscle and glands of thoracic and abdominal organs and for cardiac muscle of heart, affernent input from thoracic and abdominal organs, bloos-oresssure monitoring

vagus

…: motor function, efferent output for skeletal muscles of pharynx, larynx, neck and shoulder

Accessory

…: motor function, tongue movement

Hypoglossal

…: the subjective awareness of the external world and slef (thoughts and perceptions)

consciousness

…: conscious experience depends on “brainweb” separate bits of locally-processed subconscious information are momentarily broadcast throughout the brain (to a global workspace) - only when information is distributed to much of the cortex, does unity of mind arise

Global workspace theory

…: normal variation in awareness/alertness

sleep-wake cycles

Wakefulness not a constant level of arousal but vaires from …

maximum alertness to drowsiness

…: different brain waves in electroencephalogram

different arousal

…: a record of summed postsynaptic activity, but not APs

electroencephalogram

…: collective acitivity across 10^5 - 10^6 cortical neurons

brain waves

Type of brain wave depends on level of …

cortical arousal

Generally higher arousal → … (delta (13Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-30Hz), gamma (>30Hz))

higher frequency

The higher the frequency the …

smaller the amplitude

EEG is important diagnositic tool of cerbral dysfunctin especially in …

epilespsy

A ool in cognitiveneuroscience and electrophysiology research to investigate neural correlates of preforming various tasks or …

perceiving various stimuli

…: no conscious awareness of external world but instead inward conscious experiences, an active process where the brains level of activity is not reduced

Sleep

Two types of sleep: …

slow wave sleep, paradoxical sleep (REM)

…: four stages with increasingly deep sleep manifested as wave patterns of decreasing frequency, stages 1-4 (30-45 minutes)

Slow wave sleep

…: always pass through slow-wave sleep before paradoxical sleep

normal sleep cycle

… need longer paradoxical sleep

infants

… stage 4 and paradoxixala sleep decline

elderly

Behavior/physiological patterns associated with slow wave sleep: … (4)

muscle tone maintained, RR HR BP remain regular, easily awakened, rarely dreams but nightmares

Behavioral/Physiological patterns of Paradoxical sleep: … (4)

Abrupt inhbition of muscle tone, RR HR irregular, BP fluctuate, dreaming with imagery

Sleep - wake cycle mechanism: … (3)

arousal system, slow wave sleep center, paradoxical sleep center

…: brain stem ARAS + hypothalamus → keep awake

arousal system

…: hypothalamus, sleep on neurons → slow wave sleep

Slow wave sleep center

…: Brain stem, REM sleep-on neurons → switch to REM sleep

Paradoxical sleep center

…: sleep allows the brain to restore biochemical processes from progressively degradation during wakefulness

“catch up” time sleep theory

Adenosine continues to … the longer the person is awake

rise

Adenosine … → induced slow wave sleep

inhibits arousal center

Adenosine levels … during sleep

drop

Administration of adenosine → …

induces normal sleep

Administration of … blocks adenosine receptors → awakes from drowsiness

caffeine

Sleep may repair damage from …

free radicals

Sleep may cleanse the …

interstitial fluid

Sleep may help pathways regain …

sensitivity

…: irresistible sleep atacjs during the day → directly into REM sleep

Narcolepsy

…: can more purposefully

minimally conscious state

…: no detectable awareness

vegetative state

…: total unresponsiveness to external stimuli, assessment by Glasgow scale

Coma

…: caused by traumatic brain injury, temporary loss of consciousness, headache, confusion, dizziness, and amnesia, repeated blows to head → chronic traumatic encephalopathy

concussion