Neuro Exam 3

What are movements?

Simple reflexes with brief muscle activation (Examples include: blinking, hiccup)

What are acts?

These are action patterns. They are complex sequential movements.

What is a motor plan?

It is a motor program, it is essentially a set of muscle commands that are established before the action occurs.

Open-loop control vs Closed-loop control

Open loop maximizes speed, it has no guiding external feedback and is responsible for Ballistic movements. \n Closed-loop maximizes accuracy. It is responsible for Ramp movements.

What are ballistic movements?

They are rapid and are completed no matter what sensory feedback is received.

What are ramp movements?

These are slower, sustained motions that are guided by feedback.

The Hierarchy of motor control systems.

Skeletal system as well as muscles power movement, Spinal cord controls skeletal muscles, Brainstem integrates motor commands, Primary motor cortex initiates commands for action. Nonprimary motor cortex initiates cortical processing, Cerebellum and basal ganglia tweak these systems.

\
antagonist muscles vs synergist

Antagonists contract when other muscle extend. Synergists act together.

What is a muscle composed of?

Muscle Fibers

What do muscle fibers contain?

They contain two kinds of regularly arranged and overlapping filaments. (The two types of filaments are myosin (Thick filaments) and actin (thin filaments).

What are the two kinds of muscle fibers?

Slow-twitch and Fast-Twitch

Slow-twitch fibers?

Contract slowly but resist fatigue. First to be recruited.

Fast-twitch fibers?

Contract rapidly but fatigue easily. So the last to be recruited.

What is a neuromuscular junction and what is the neurotransmitter released here?

This is where a motor neuron terminal and muscle fiber meet. Acetylcholine is released here.

What is a motor unit?

It is one motorneurons axon and all of its target fibers.

What type of muscles have a few muscle fibers per axon?

Muscles that make fine, precise movements.

What is proprioception?

It is the collection of information about body movements and position.

What are the two kinds of muscle proprioceptive receptors?

Muscle spindles and Golgi tendon organs

What do muscle spindles respond to?

Muscle stretch

What do golgi tendon organs respond to?

Muscle Contraction

What is Spasticity?

It is impaired control of the stretch reflex

What is the general pathway for the pyramidal tract?

It is a two neuron pathway. Neuron 1 goes from the primary motor cortex to the pyramid in the medulla, where it crosses over. It then goes down the spinal cord and ends at the anterior horn cell. Neuron 2 goes from the mororneuron to the muscle.

True or False? Primary motor cortex changes as a result of learning.

True

What makes up the Nonprimary motor cortex?

Supplementary motor area and Premotor cortex

What does the SMA do?

encodes sequence of movements.

What does the Premotor area do?

These neurons fire just before performing an activity.

What are the neurons that fire when observing another individual performing a task?

Mirror neurons.

What kind of cells does the Cerebellum cortex contain?

Purkinje cells (\*these cells ONLY send INHIBITORY messages)

How does the cerebellum guide movement?

Through inhibition.

What is the central pattern generator?

It is a neural circuit that generates rhythmic behaviors. (Rhythmic activities, such as walking, are generated in the spinal cord)

Neurons that fire after a movement begins are in?

The cerebellum

Strength vs tone

Strength is largely a pyramidal function. Tone is largely an extrapyramidal function.

What does pyramidal damage lead to?

Weakness

What does Extrapyramidal damage lead to?

It impairs movement control

What is a primary disorder of muscle?

Myopathy

What is muscular dystrophy?

progressive degeneration of muscle. These patients make no dystrophin or have an abnormal dystrophin molecule.

What is Dystrophin?

it is a protein needed for normal muscle function. It is produced by the X chromosome.

What is Myasthenia gravis?

It is an autoimmune disorder where patients develop antibodies against their own ACh receptors. (this is the case where weakness of muscles develops over the day and resolves with rest/sleep. )

What is a way to treat Myasthenia that was performed on the dog shown in the video during class?

Using an acetylcholine agonist. (tensilon test)

What does poliovirus do?

It destroys spinal motorneurons and sometimes cranial motoneurons.

What is ALS?

This is also known as Lou Gehrig's disease. It consists of the degeneration of motoneurons and consequent loss of their target muscles.

What do spinal cord injuries lead to?

Flaccid Paralysis

What is lost during flaccid paralysis?

Reflexes, sensation and strength below level of the injury are lost

What is Apraxia?

Inability to sequence movements, though no muscle paralysis exists.

A disorder of the neuromuscular junction is?

Myasthenia Gravis

What are some symptoms of Parkinson disease?

Tremor, Bradykinesia, Shuffling gait, and Postural instability.

What is an inherited cause of Parkinson's?

A defective gene for alpha-synuclein.

Other than the inherited cause for Parkinson's what is another cause for it?

Degeneration of dopamine cells in the substantia nigra, which project to the basal ganglia.

What is one way of reducing the symptoms of Parkinson's?

Treating the patient with L-dopa which is a precursor to dopamine.

What is Huntington chorea caused by?

Progressive destruction of the caudate nucleus and putamen.

What is the gene responsible for this disorder?

Trinucleotide repeat. It is variable in length and if it repeats too many times the disease develops.

What is ataxia?

This is where cerebellar damage impairs motor control. (alcoholism causes gait ataxia; this is where Purkinje cells die)

Continuous uncontrollable writhing is?

Chorea

What is dystonia?

It is sustained, patterned muscle contractions. Patients also have an abnormal sustained posture and Basal ganglia dysfunction.

What is Tourette syndrome?

It is Tics and OCD. This is a disorder of the basal ganglia and cortex.

What is Hemiparetic gait?

It is caused by motor cortex damage, such as stroke that causes motor impairment. These patients tend to have a weakness of voluntary movements.

Tremor is seen in?

Parkinson Disease

Why sleep?

Sleep helps animals avoid predators. Sleep saves energy. Sleep, especially dreaming, improves processes that consolidate learned material

Diurnal vs Nocturnal

Active during the light, and active during the dark respectively.

How long are circadian rhythms?

About 24 hours

How does light information go from the eye to the SCN?

Retinohypothalamic path.

In the case where the SCN is lesioned, what happens to sleep?

Circadian rhythms are disrupted. This means that individuals with SCN lesions will sleep a normal amount but it will be off schedule due to the loss of the circadian rhythms.

Which stages of sleep are considered slow wave sleep?

Stages 1-4

REM sleep?

this is rapid eye movement sleep. EEG shows Beta waves (It's important to note that an EEG of an individual in an awake state shows Beta waves as well). Your BR and HR are increased and muscles are relaxed (suppressed)

How long do sleep cycles last?

About 90-110 minutes. It's important to note that cycles early in the night have more stage 3 and 4 SWS, while later cycles have more REM sleep.

Do we dream in REM or non REM sleep?

Both

What type of dreams do we have in REM sleep?

Vivid dreams that are characterized by visual imagery and the dreamer feels as if they are there. (NonREM dreams are less emotional and less visual.)

What happens to sleep as we age?

Total time asleep declines and awakenings increase.

How is infant sleep characterized?

Shorter sleep cycles and more REM sleep.

How do you wake up?

RAS (reticular activating system) turns on the brain

How do we fall asleep?

the VLPO (ventrolateral preoptic) nucleus turns off the brainstem

What does the pontine system do?

It triggers REM sleep and paralyzes your body.

What does the upper brainstem system do?

It activates the cortex

What are effects of sleep deprivation?

Increased irritability, Difficulty in concentrating, episodes of disorientation, Effects vary with age

What did Zach have?

Narcolepsy which lead to a sudden loss of muscle tone (cataplexy)

What is Narcolepsy characterized by?

Frequent sleep attacks. These individuals have insomnia and excessive daytime sleepiness. These individuals do not go through long SWS before REM sleep.

What do narcoleptic dogs have?

They have a mutant orexin receptor in the brainstem.

What does orexin normally do?

\
It prevents the transition from wakefulness directly into REM sleep. Orexin is released just as you wake up.

What happens to orexin receptor in narcoleptic people?

They have an autoimmune on their orexin receptor

What are some other things that orexin is involved in?

Appetite, somatomotor activation, vigilance, tachycardia and hypertension.

What is sleep paralysis?

brief inability to move just before falling asleep or just after waking.

When do Night terrors and enuresis occur?

Slow wave sleep

What is Somnambulism?

also known as sleep walking. This occurs during stages 3-4 SWS and may persist through adulthood

What are some characteristics of Sleep apnea?

Breathing stops, Chest/diaphragm muscles relax too much, snoring/gasping and daytime sleepiness.

How is sleep apnea treated?

CPAP which prevents the collapse of airways.

Dr. Miller showed a video of a baby jerking it's hands while sleeping, what is the diagnosis?

Sleep Myoclonus

SIDS?

this is sleep apnea from immature respiratory pacemaker systems or arousal mechanisms.

What happens during REM sleep behavior disorder? (RBD)

This is the case where the paralysis that normally occurs during REM sleep is incomplete or absent causing the individual to act out their dreams.

In the case where an organism has there cerebellum severed what would happen to sleep?

Nothing, this individual will sleep normally.

What does continued use of sleeping pills do?

Makes them ineffective due to down regulation of receptors, Changes in your sleep pattern that persist after the drug is stopped, and it can lead to drowsiness and memory gaps.

What percentage of the population is affected by Schizophrenia? And what is a key symptom of this disorder?

1% . Dissociative thinking which can also be referred to as impaired logical thought.

What are the positive symptoms of Schizophrenia?

These are abnormal behaviors that are gained. These include hallucinations, delusions and excited motor behavior.

What are the negative symptoms of Schizophrenia?

\
These are lost functions. These include Slow thought and speech, emotional and social withdrawal as well as Blunted affect.

What are the Cognitive symptoms of Schizophrenia?

disorganized thoughts, difficulty concentrating and following instructions.

In monozygotic twins, if one of them develops schizophrenia, what is the likelihood that the other one develops it as well?

50%

What does the Vulnerability model of Schizophrenia explain?

It explains that Environment exposures combined with a person's genetic vulnerability affect the likelihood of schizophrenia. This model explains that if the threshold is exceeded then the illness occurs.

What is a finding in the hippocampus of an individual suffering from Schizophrenia?

Pyramidal cells in the hippocampus are disorganized.

True or False? The hippocampus and amygdala in some individuals suffering from schizophrenia is larger

False. They are actually smaller.

Schizophrenics have a deficiency in ________ particularly in hippocampus and prefrontal areas. Fill in the blank and define the term in the blank.

Reelin. Reelin is a "stop" signal for migrating cells.

When looking at a functional brain scan of individuals suffering from Schizophrenia what would one notice?

Under-activity of temporal and frontal lobes. This is also known as Hypofrontality