Reticular formation and Limbic system Flashcards
What are the Reticular formation (RF) functions?
- Control of skeletal muscles
- Control of somatic/visceral sensations
- Control of ANS
- Control of endocrine functions
- Influence on circadian rhythms
- Control of levels of consciousness
where does the Reticular formation extend through?
The RF can be divided into cell columns in the brainstem, what are these?
what structures can we find in each?
brainstem
- Median: raphe nuclei
- Medial: motor coordination
- Lateral: breathing (expiration)
identify the reticular formation median, medial, and lateral cell columns within the brainstem.
what forms the Ascending Reticular Activating System (ARAS)?
What is the funcitno of the ARAS?
ACh/NE axons project from the rostral RF to intralaminar nucleus of thalamus which in turn project to the cortex
maintains consciousness.
Thalamic lesions can result in coma if what structure is affected?
intralaminar nuclei
Transection through midbrain results in disconnection of ARAS from cortex will result in what?
Transection through lower medulla/uppermost part of spinal cord will result in what?
Transection at midpontine level will result in what?
Produces coma or slow-wave sleep.
ARAS functions normally.
Constant wakefulness
wakefulness produced by midpontine transection suggests what?
that lower regions of the RF (below the transection) are involved in ‘turning off’ the ARAS periodically
so lower part controls sleep/wakefulness cycles.
serotonin depletion causes what?
Raphe afferents synapse where?
Serotonin neurons are found where?
insomnia
at various levels of the Reticular formation
Raphe nucleus
ARAS projections also inhibits what and what is its funciton?
Is sleep an active process? why?
what turns off the ARAS? how does it work?
the reticular nucleus of the thalamus, which normally functions to inhibit the relay of sensory information to cortex.
yes, because parts of the brain have to work to maintain sleep (thalamus, raphe, hypothalamus).
the reticular nucleus; During sleep, this nucleus actively inhibits sensory transmission through the thalamus allowing to you to sleep better because you’re less aware of external environment.
what is habituation?
what structure is involved in habituation?
brain ignores repetitive stimuli
reticular formation
Identify the ‘states’ of consciousness
- Confusion: Disorientation, ‘not thinking clearly’
- Somnolence: Semi-consciousness or drowsiness. Stimuli will arouse patient but only for the duration of the stimuli.
- Stupor: Patient responds in a limited way to painful, or extremely intense, stimuli.
- Coma: No response to external stimuli.
The Glasgow Coma Scale tests which 3 responses?
how many points are in each of the responses?
visual - 4
verbal - 5
motor - 6
what are the point given for the eye response in the glasgow scale?
- No eye opening.
- Eye opening to pain.
- Eye opening to verbal command.
- Eyes open spontaneously.
what are the point given for the verbal response in the glasgow scale?
- No verbal response
- Incomprehensible sounds.
- Inappropriate words.
- Confused
- Orientated
what are the point given for the motor response in the glasgow scale?
- No motor response.
- Extension to pain.
- Flexion to pain.
- Withdrawal from pain.
- Localising pain.
- Obeys Commands.
what is the The Limbic System?
what are the connections of the limbic system?
what does this allow it to control?
involved in the expression and control of emotional behavior and memory related to emotions
hypothalamus: can influence autonomic and endocrine functions.
what are the symptoms of Wernicke’s Encephalopathy?
why does it happen?
how do you treat?
- Ocular palsy
- Gait ataxia
- Mental confusion
most common: results from chronic alcohol consumption
other reason: subdural hematoma or after bariatric surgery
vit B1 - thiamine
after having wernicke’s syndrome due to alcohol, continued alcohol use would result in what?
what will it damage?
what are the symptoms?
Continued chronic alcohol use can lead to Korsakoff’s Syndrome
mammillary bodies
anterograde memory deficits, mental confusion, and confabulation*, Hemorrhages may also occur in diencephalon and brainstem regions, in the gray matter surrounding 3rd and 4th ventricles, and cerebral aqueduct.
Kluver bucy, why does it happen?
what are the symptoms?
Bilateral amygdala lesions, Fronto-temporal lobe lesion/surgery, Pick’s disease, Meningitis/encephalitis, etc.
- Hyperphagia: gluttony, obesity.
- Hypersexuality: inappropriate social/sexual
- behavior, increased sexual activity.
- Visual agnosia (psychic blindness): inability to
- recognize objects visually.
- Docility/fearlessness: previously fear-producing
- stimuli do not produce fear.
what is paroxysm?
what is considered a Paroxysmal disorder?
- Sudden fit or outburst.
- Sudden onset of transient symptoms due to underlying medical/psychiatric condition.
- Attacks can last from seconds to minutes, and occur 1 or 2x/day to 100’s/day.
- Migraines
- MS
- trigeminal neuralgia
what are symptoms of Migraines?
Paroxysmal Hemicranium?
Trigeminal neuralgia?
Multiple Sclerosis?
- Migranes: Auras, blurry vision, nausea, vomiting, photophobia.
- Paroxysmal Hemicranium: Discussed in Pain lecture as Hemicranium Continua.
- Trigeminal neuralgia: ‘Lightning-quick’ strike of pain typically in response to non-noxious stimuli.
- Multiple Sclerosis: Multiple possible neurologic symptoms.
identify what are the symptoms of these paroxysmal disorders:
- Seizures
- Pseudo-seizures
- TIA’s
- Syncope.
- Seizures: Overly-excited brain region causes seizures (definitely a sudden onset neurological symptom).
- Pseudo-seizures: Look like seizures but EEG is normal. Psychologically based; Childhood abuse or trauma shows up in many histories of pseudo seizure patients.
- TIA’s: Transient CVA results in transient neurological symptoms.
- Syncope: Brief loss of consciousness with fast recovery.
what symptoms precedes syncope ?
what can cause fainting or syncope?
- lightheadedness, nausea, palpitations
- amilial dsyautonomia, orthostatic hypotension, metabolic abnormalities, anemia, dehydration, hyperventilation
what are the Types of Syncope?
define each
- Vasovagal or Cardioneurogenic or Reflex syncope:
* most common
* Causes: changes in position, dehydration, fatigue
* the ANS does not respond fast enough to sudden changes. - Cardiac: Heart condition resulting in decreased blood flow to brain.
- Neurologic: Seizure, TIA, hydrocephalus, migraines, stroke.
- Pseudosyncope: Syncope episode in the absence of physical symptoms.
If the trigger for vasovagal syncope is specific, it is often called?
Situational
how do you Test for Syncope?
- Blood tests: Check for low blood sugar or dehydration.
- EEG and Echocardiogram: For heart abnormalities.
- Tilt Table: Patient strapped to table and…well, tilted. Good for diagnosing dysautonomia or syncope).
- Therapy/Behavioral: Some patients with vasovagal syncope respond well to cognitive behavioral therapies.
how do you diagnose MS?
Most patients initially present with what? and what is it?
how do you treat?
how do you treat to reduce the likelihood of developing MS after a CIS episode?
- lumbar puncture or MRI
- CIS, Clinically Isolated Syndrome; an episode of MS-like symptoms caused by demyelination
- high dose steroids, or plasmapheresis
- Interferon
what is:
- Peripheral neuropathy?
- Mononeuropathy?
- Polyneuropathy?
- Peripheral neuropathy: Damage to nerves outside the brain or spinal cord. Several types:
- Mononeuropathy: Damage/loss of a single nerve or nerve group. (Ex. Carpal tunnel, sciatica).
- Polyneuropathy: Many peripheral nerves lose function simultaneously (Ex. Guillan Barre, diabetes, kidney failure, Lyme disease, alcoholism, and many others).
