#1 Reticular Formation Flashcards
______ is the Central core of the brainstem.
Reticular formation
The Reticular formation is important in the regulation of what 6 things?
- Posture
- Some stereotypic motor behaviors
- the internal environment
- Pain regulation
- Sleep & wakefulness
- Emotional tone
What are the 3 zones of the reticular formation? DESCRIBE EACH ONE.
- Raphe or median = just adjacent to sagittal plane.
- Paramedian or medial (Middle) = mixture of large and small neurons, source of most ascending and descending projections.
- Lateral = prominent in rostral medulla and caudal pons, primarily involved in cranial nerve reflexes and visceral functions.
What causes sleep paralysis?
When you wake up but your pons does not….
RF divides into 3 tracts… what are they?
Two reticulospinal tracts:
- 1 Medial: pons; ipsilateral, descends near MLF & in anterior funiculus.
- 2 Lateral: medulla, descend bilaterally in lateral funiculus.
The Reticular formation is the major alternative to the ________ in regulating spinal motor neurons.
Corticospinal tract
Reticulo spinal tract neurons receive input from many areas including….
Cerebral cortex, basal ganglia, substantia nigra
The vertical gaze center is found where?
Midbrain
The horizontal gaze center is found where?
Pons
Mastication pattern generator is located where?
Supratrigeminal Nucleus
The Medulla “Vital center” controls what?
Locomotion
Heart Rate
Respiration
Swallowing & Vomiting
Problems with the Reticular Formation can cause what stereotyped movement disorder?
Bruxism (tooth grinding)
*both opening and closing muscles are contracting at same time.
What is the Central cause theory regarding Bruxism?
Sleep-related dysfunction cause bruxism. Input to supratrigeminal nucleus may be from basal ganglia, lateral hypothalamus and central nucleus of the Amygdala.
How does the Reticular Formation moderate transmission in Pain pathways?
Periaqueductal gray (PAG) is central one well described pain suppression system.
PAG receives pain info from ______ fibers.
Spinomesencephalic fibers
PAG runs to _______ then to _______.
Raphe and then to posterior horn of spinal cord/spinal V nucleus.
_______ work to control pain by activating PAG-raphe at multiple levels.
Opiates
How is the Reticular formation related to Autonomic Reflex circuitry?
- A lot of visceral information reaches the RF.
- RF responds to environmental changes and PROJECTS to brainstem autonomics nuclei and spinal cord.
RF Centers controlling inspiration, expiration and rhythm of breathing are located where?
In pons and medulla.
Where are heart rate and blood pressure controls located?
Medulla
True or false. The Reticular formation is critical in arousal and consciousness?
True!
- The RF projects to the thalamus and cortex!
- Midbrain and pons RF get input from multiple sensory modalities (pain &spinoreticular fibers)
- Project to thalamic intralaminar nuclei, ehich diffusely project to cortex.
- Heightens arousal in response to sensory stimuli or tasks that demand attention.
RF _______ & ______ work together to modulate cortical activity.
Thalamic intralaminar nuclear projections & monoamine reticular projections
What is the main monoamine of the brainstem?
Norepinephrine
*Also dopamine and serotonin
What is the neurochemical signature of the hypothalamus?
Histamine containing neurons.
What is the neurochemical signature of the Telencephalon?
Acetylcholine
Where are Noradrenergic neurons found?
Medulla
- solitary nucleus (memory enhancement)
Rostral Pons
- Locus Ceruleus
- Cortex (arousal ) vigilance and attention.
- Ventrolateral medulla
- Spinal cord = pain regulation.
Where is the Locus Ceruleus?
At base of Cerebellar Stalk ( looks like a black/blue sliver)
True or false. Noradrenergic projection are very diffuse.
True! especially in somatosensory cortex
What might a shortage of Norepinephrine cause?
Clinical depression
- Locus Ceruleus activity is reduced.
- Parkinsons disease patients often suffer from depression b/c locus ceruleus neurons are lost.
- Drugs used to treat depression increase rate of firing at Locus ceruleus.
What might increased levels of Norepinephrine cause?
Panic disorder
What do the Neurons of the Locus Ceruleus do?
Respond to novel environmental stimuli.
- Stimuli produces:
- Increased state of arousal.
- Feeling of anticipation
- Norepinephrine released in cortex facilities attention to selected stimuli.
Where is Norepinephrine realized to suppress incoming pain signals?
Spinal nucleus and spinal cord.
Where are Dopaminergic neurons of the midbrain located?
- Substantia Nigra (putamen & caudate)
- Ventral tegmental area (limbic system)
What are the divisions of the Ventral Tegmental Area responsible for? (2)
Mesocortical fibers = Organized thinking & planning; Heavy projections to frontal cortex.
Mesolimbic fibers (Nucleus accumbens, amygdala) = emotional reward & drug dependency.
Nigrostriatal neurons are important in what kind of function?
Motor function
______ is major source of dopamine.
Ventral Tegmental area
Schizophrenia is thought to be linked with problems of what area?
Ventral segmental area
- Disorganized thinking (Frontal lobe)
- Hallucinations (Limbic system/Temporal lobe)
Schizophrenic hallucination are associated with ______ of dopamine in the limbic system.
High levels
Schizophrenic social withdrawal is associated with _____ of dopamine levels in the prefrontal cortex.
Low levels
Where are Serotonergic neurons located?
Pretty much all brainstem levels in raphe….so Raphe Nuceli.
What is the ultimate function of Serotonergic neurons?
Help you focus and ignore distractions
The midbrain raphe nuclei up to all regions of the cortex do what?
- attention = inhibition of distracting nuclei.
- Hypothalamus = day night cycle.
The Medullary raphia nuclei down to spinal cord are know as what?
Nucleus Raphe Magnus
Selective Serotonin Reuptake inhibitors are used for what?
Treatment of Clinical depression
Serotonergic projections are very diffuse, but especially in what 2 areas?
Sensory and Limbic Areas
What do low level of serotonin cause?
- High carb consumption
- Binge eating
- Carb preference in obese women
What do high levels of serotonin cause?
- compulsive behavior and anorexia nervosa.
Drugs that increase serotonin levels would be used to treat what?
Depression and Anxiety
____ produces acetylcholine.
Cholinergic neurons found in the basal forebrain; basal nucleus (of meynert) & Part of RF = dorsolateral pontine tegmentum.
What is one of the functions of the Dorsolateral pontine tegmentum of the RF?
Sleep and wakefulness
Where do cholinergic projections project to?
to cortex mostly.
* a little bit to limbic also.
