Cerebral cortex II Flashcards
If you want to hinder someone’s ability to process/speak language, which major area would be best to lesion?
Sylvian fissure
What’s the name of the structure that connects B’s and W’s areas?
Arcuate fasciculus
What are the basic sx of Broca’s aphasia?
Can comprehend speech but can’t get any words out.
What are the basic sx of Wernicke’s aphasia?
Can speak in regular words/sounds but they make no sense together and pts don’t understand anything.
What neuroscientist discovered the function of the reticular formation?
Magoun
In what part of the brain would you find the reticular formation?
(What afferents does it receive?)
(What efferents does it give off?)
- Brainstem: it’s a coordination network for brainstem nuclei
(- Premotor afferents come in)
(- Output to nearby motor and sensory nuclei)
What’s the general function of the reticular formation?
*Allows convergence of somatosensory information and divergence of efferent outputs
What are the 3 main specific functions of the reticular formation that we talked about?
- Pattern generator (eye movements, swallowing, chewing, coughing sneezing, locomotor)
- Control center (resp, CV, peeing)
- Nociception
What zones of the reticular formation should we be aware of?
- *Midline (raphe) RF
- Paramedian RF
- Lateral RF
What’s the general fcn of the midline (raphe) RF zone?
What NT is used here?
- Part of the diffuse modulatory system
- Aminergic neurons (use monoamines- serotonin is monoamine that we learned for Raphe)
What’s the general fcn of the paramedian RF zone?
“Effector zone” w/different projections out (midbrain, pons, medulla)
What’s the general fcn of the lateral RF zone?
Sensory (*ascending sensory pw’s are off to the side, so makes sense)
Where does the RF get its afferents from (general answer)?
“Basically everything”
What are the general sites of efferent RF termination?
Is RF’s efferent info general or specific?
- Brainstem
- Spinal cord
(general/gross motor info sent, not specific like moving pinky)
Give an e.g. of a type of things efferent info from the RF, going to the spinal cord, would effect.
General things like posture, locomotion
Where would you find “diffuse modulatory systems” (DMS)?
Around the borders of the RF
What does the ascending reticular activating system (ARAS) do?
- Plays a role in level of alertness, sleep/wake rhythms, alerting (startle) reaction
- Plays a role in activating the entire cortex (along w/other playas)
- It’s a DMS
What are some e.g.’s of other areas that would help the ARAS wake up or put to sleep the cortex?
- Cholinergic neurons (close to locus ceruleus)
- Orexin, a neuropeptide from the tubomammillary body
- Cholinergic neurons (from basal nucleus of Meynert)
What does the cerebral cortex do to the DMS?
- Influences alertness (as can visual, auditory and mental imagery)
- Inhibits other sensory input to allow focusing of attention.
What are some major regions of the DMS that we’ve gone over?
- VTA
- Raphe nuclei
- Locus ceruleus
- Magnus raphe nucleus (inferior)
What are the major functions of the DMS (serotonergic and adrenergic systems)?
- Sleep arousal mechs
- Integrative behavioral and neuroendocrine functions
- Modulate actions of other NTs
- Brain growth and devo
- Pain suppression
What would happen if you lesioned the VTA, behaviorally?
More risky behavior like gambling and being a gigallo
Where do the midbrain raphe nuclei project (just an e.g.)?
What NT is most important here?
Entire cortex!
- 5-HT
What is the “level” of one’s consciousness dependent on, generally?
Diffuse modulation projections
Where is orexin produced?
Lateral hypothalamus
What systems maintain consciousness?
Diffuse modulating systems
What NT is associated w/the midbrain RF regarding the maintenance of consciousness?
ACh
What brain nucleus is associated w/sleep and where would you find it?
Suprachiasmatic nucleus (SCN) - Found above the optic chiasm as part of the hypothalamus
How long does it normally take to enter sleep?
What if you pull an all-nighter?
60-90 min
- Minutes probably
On EEG, what differences in amplitude, freq, and synchronization would you see b/w REM and nREM sleep?
- nREM: large amp, slow freq, sync’d
- REM: small amp, fast freq, unsync’d
What differences in m. tone and arousal would you see b/w REM and nREM sleep?
- nREM: low m. tone, progressively higher arousal
- REM: Nearly abolished m. tone, high arousal level
What differences in dream, autonomic activity (symp vs parasymp), and HR/RR regularity would you see b/w REM and nREM sleep?
- nREM: vague dreams, ^ parasymp, regular pulse/resp
- REM: vivid dreams, ^ symp, irregular pulse/resp
What area in the hypothalamus does the SCN interact w/to regulate sleep/wake cycles?
Preoptic area (SCN acts on it)
What 3 areas does the preoptic area interact w/to regulate sleep/wake cycles?
- SCN (gives POA input)
- Wakefulness network (acted on by POA)
- Medullary RF (bilateral)
What areas does the medullary RF interact w/to regulate sleep/wake cycles?
- Wakefulness network (acted on by mRF)
- Preoptic area (bilateral)
What 3 areas does the wakefulness network send efferent signals after receiving input from the preoptic area and the medullary RF?
- Cortex
- Thalamus -> cortex
- REM machinery (pons)
What’s the main issue w/taking sleep meds?
Suppresses REM sleep
What NT are people missing who have narcolepsy and cataplexy?
Orexin (has role in wakefulness)
Define cataplexy.
Strong emotion/laughter leads to loss of motor tone while remaining conscious (you fall over)
Describe the sleep pattern of a narcoleptic w/cataplexy.
How would you induce this state?
They go rapidly into REM and often act out their dreams
- Stay up for a long time
If you were focussing on 1 task and didn’t even notice someone else talking to you, what part of your brain would be responsible for this focussing of attention?
Cerebral cortex, inhibiting that info from reaching the diffuse modulatory systems.
