reticular formation Flashcards
The ___ is a phylogenetically old, central core of the brainstem, which extends into the cerebrum as the ___.
- reticular formation
- hypothalamus
What functions are the RF important for
- posture
- stereotypic motor behaviors
- internal environment
- pain regulation
- sleep and wakefulness
- emotional tone
3 zones of RF
- Raphe (median) nuclei
- Medial zone
- Lateral zone
Why is the Medial zone significant?
- source of most ascending and descending projections
Where is the lateral zone most prominent and what is its function?
- Prominent in the rostral medulla and caudal pons
- Primarily involved in cranial nerve reflexes and visceral functions
Which two reticulospinal tracts serve as major alternative to corticospinal tracts in regulating spinal reflexes?
- Medial
- Lateral
- Only noxious stimuli to evoke a reflex
The reticulospinal tract neurons receive input from the ___, ___, ___.
- cerebral cortex
- basal ganglia
- substantia nigra
The ___ begins in the pons ipsilaterally, descends near the MLF and in the anterior funiculus. It facilitates ___ movements and ___ muscle tone.
- Medial tract
- voluntary movements
- increases
The ___ is found in the medulla, descends bilaterally in the lateral funiculus, and ___ voluntary movements, and ___ muscle tone.
- lateral tract
- inhibits
- decreases
Name the rhythmic motor patterns in the brainstem reticular formation.
- gaze centers
- mastication (supratrigeminal nucleus in pons)
- locomotion (pons)
- heart rate
- respiration
- swallowing/vomiting
Malocclusion results in premature and one sided contact of teeth, jaw movements continue in an attempt to reach resting position is which theory of bruxism?
peripheral causes theory (based on clinical observation)
Sleep-related dysfunctions, input to supratrigeminal nucleus may be from BG, lateral hypothalamus, and central nucleus of amygdala relates to which theory of bruxism?
central causes theory
RF, especially the ___ can suppress or facilitate pain depending on the circumstances.
Periaqueductal grey (PAG)
Sensory information from the ___ reaches the PAG as spinomesencephalic fibers
anterolateral pathway
The PAG also receives input from the ___, ___, and ___ which may contain behavioral state info letting the body know whether pain should be activated or suppressed.
- hypothalamus
- cortex
- amygdala
The PAG sends signals to the ___ which send signals to the ___.
- raphe
- posterior horn of the spinal cord (afferents)/spinal V nucleus
The ___, is responsible for sleep-wake cycles, thus mediating various levels of alertness.
- Ascending reticular formation (AKA reticular activating system)
The ___ is involved in posture and equilibrium as well as ___.
- Descending reticular formation
- autonomic nervous system activity
The descending reticular formation also plays a role in ___.
motor movement
How do opiates suppress pain in the RF?
- work by activating the PAG-raphe at multiple levels.
- Opiate receptors are abundant in the PAG, rap he, and posterior horn of the spinal cord.
___ can inhibit the STT directly, or indirectly by activating interneurons that inhibit the STT.
Raphe
- (STT= sensory from the skin the thalamus)
The RF has centers controlling inspiration, expiration and rhythm of breathing in the __ and __.
pons and medulla
Heart rate and BP control centers are found in the ___
medulla
Where do we find norepinephrine receptors?
- lateral zone of brainstem (rostral medulla and rostral pons)
Were do we see dopamine and serotonin receptors?
Median raphe of the brainstem
Where are histamine containing neurons found?
Hypothalamus
Where do we find acetylcholine receptors?
- telencephalon and pons
Where is the Solitary nucleus found, and what type of receptors are located here?
- found in the posterior aspect of the medulla and is a receptor for norepinephrine
- functions in memory enhancement
Where is the Locus ceruleus located, and what type of receptors are located here?
- found in the posterior aspect of the rostral pons
- functions in cortex (arousal) vigilance and attention
Norepinephrine is also found in the ventrolateral medulla, and is used as a ___.
pain regulator
Norepinephrine released in the trigeminal spinal nucleus and spinal cord is used to ___.
suppress incoming pain signals.
Noradrenergic projections innervate practically the entire CNS; they have heavy projections to the ___.
somatosensory cortex
___ levels of norepinephrine can lead to clinical depression
decreased
Decreased levels of norepinephrine lead to reduced ___ activity
locus ceruleus neuron
___ patients often suffer from depression due to the fact that the locus ceruleus neurons are lost.
Parkinsons
___ is caused by an increase in norepinephrine levels.
Panic disorder
Dopaminergic neurons are found in the midbrain and include the ___, and ___.
- Substantia Nigra (putamen and caudate)
- Ventral tagmental area
The ___ is involved in motor activity, and can be affected in patients with Parkinson’s.
Substantia nigra
The ___ is the major source of dopamine and contains two tracts.
Ventral tegmental area (limbic system)
What are the two tracts of the ventral tegmental system?
- Mesocortical tract/fibers
2. Mesolimbic tracts/fibers
What is the purpose of the mesocortical tract?
- Responsible for organized thinking and planning
- sends heavy projections to frontal cortex which organize and initiate behaviors
Whats the purpose of the mesolimbic tract?
It is involved in emotional reward and drug dependency.
___ is involved in social withdrawal due to low levels of dopamine in the prefrontal cortex.
Schizophrenia
___ occur due to high levels of dopamine in the limbic system.
Hallucinations
Serotonergic neurons are located at pretty much all brainstem levels in ___.
raphe
Raphe nuclei in the ___ send signals to all regions of the ___ and are used for attention inhibition of distracting stimuli.
- midbrain
- cortex
___ raphe nuclei send information to the ___ with regards to day night cycle.
- Midbrain
- hypothalamus
___ raphe nuclei send signals to the ___ in pain suppression. More specifically this is done by the ___.
- medullary raphe
- spinal cord
- nucleus raphe magnus
Serotonergic neurons can also cause clinical depression through ___.
Selective serotonin reuptake inhibitors (SSRI)
Low levels of ___ can be a result of high carb intake, binge eating, or carb preference in obese women.
serotonin
High levels of serotonin can lead to compulsive behavior and ___.
anorexia nervosa
Chlolinergic neurons are found in the ___.
basal forebrain; basal nucleus of Meynert
___ is a disease dealing with ACh
Alzheimers (drug treatment; cholinesterase inhibitors)
