Reticular Formation & Cerebellum Flashcards
The ___ ___ is phylogenetically a very old neural network.
reticular formation
The reticular formation is a polysynaptic network in the ____ that continues rostrally into the ___ and ____.
brainstem; thalamus; hypothalamus
What is the function of the reticular formation?
Posture stereotypic motor behaviors internal environment pain regulation sleep and wakefulness emotional tone
what are the three longitudinal zones (medial to lateral) of the reticular formation?
raphe (median) nuclei; medial (paramedian) zone; and lateral zone
The raphe nuclei is immediately adjacent to which plane?
sagittal
Which zone contains a mixture of large and small neurons and is a source of most ascending and descending projections?
medial zone
where is the the lateral zone prominently located?
rostral (upper) medulla and caudal (lower) pons
which zone is primarily involved in cranial nerve reflexes and visceral functions?
lateral zone
what two reticulospinal tracts are involved in movement control?
medial and lateral
What area of the brainstem does the medial RST begin?
pons
T/F. The medial RST remains ipsilateral as it descends.
True.
The medial RST descends near the ____ and in the ___ ____.
MLF; anterior funiculus
What area of the brainstem does the lateral RST begin?
medulla
The lateral RST descends ____ in the ____ funiculus.
bilaterally; lateral
why is the reticular formation a major alternative to corticospinal tract in regulating spinal motor neurons?
It influences spinal motor neurons directly and regulates spinal reflexes - so that only noxious stimuli evoke a reflex.
what are six examples of rhythmic motor patterns found in the brainstem reticular formation?
- gaze centers
- mastication
- locomotion (pons)
- heart rate
- respiration
- swallowing/vomitting
what three rhythmic motor patterns are controlled by the medulla’s “vital center”?
heart rate
respiration
swallowing/vomitting
A 25 y/o male presents complaining of jaw muscle discomfort upon waking. You notice abnormal wear of the teeth. What is the diagnosis?
Bruxism
sounds, abnormal wear of teeth, jaw muscle discomfort upon waking, and seen in younger individuals
With sleep bruxism, all muscles are in a state of ___.
atonia
T/F. In bruxism, the jaw muscles are co-contracted.
True. Both jaw opening and jaw closing muscles are contracted at the same time
what are the two theories on bruxism?
peripheral causes and central causes theories
Which theory states that malocclusion results in premature and one-sided contact?
peripheral causes theory
In peripheral causes theory, jaw movements continue in an attempt to reach the ___ position.
resting
What is the peripheral causes theory based on?
clinical observations and experience with treatment
With central causes theory of bruxism, what is the cause?
sleep related dysfunctions
Input to the _____ nucleus may be from ___ ___, lateral ____, and central nucleus of the ____.
supratrigeminal; basal ganglia; hypothalamus; amygdala
What pathway is key to the fact that the nervous system can suppress or facilitate pain, depending on the circumstances?
reticular formation
T/F. The periaqueductal gray is central to one well described pain excitation system.
False, The PAG is central to pain SUPPRESS system
PAG receives pain info from _____ fibers.
spinomescencephalic
PAG may also contain ___ state info - for example, should pain suppression be activated?
behavioral
Describe the pathway of RF and pain?
PAG to (magnus) raphe nucleus (in medulla) then to posterior horn or spinal cord/spinal V nuclues
Many fibers of RF liberate ___, which excites inhibitory interneurons in the posterior gray horn and spinal trigeminal nucleus.
serotonin
Raphe can inhibit ___ directly or indirectly by activating interneurons that inhibit ___. It can also directly inhibit pain ___(afferents/efferent).
STT(spinothalamic tract); STT; afferents
___ receptors are abundant in PAG, raphe and posterior horn of the cord
Opiate
A lot of ___ information reaches the RF, which responds to environmental changes and projects to brainstem ____ nuclei and spinal cord.
visceral; autonomic
T/F. Centers controlling inspiration, expiration rhythm of breathing are located in the midbrain.
False. Pons and Medulla
T/F. Heart rate and blood pressure are controlled in the medulla.
true.
RF projects to the ___ and ___ for arousal and consciousness.
thalamus and cortex
___ and ___ RF get input from multiple sensory modalities (e.g. pain) and project to ____ ____ nuclei, which project diffusely to the cortex.
Midbrain and pons; thalamic intralaminar
Which RF projections work together to modulate cortical activity?
thalamic intralaminar nuclear projections to cortex and monoamine reticular projections
___ (Unilateral/Bilateral) damage to the midbrain RF results in prolonged coma. This is known as the ___ ___ ___ ___ (ARAS). This system also has a role in sleep-wakefulness cycle.
Bilateral; ascending reticular activating system
What neurochemicals affect the brainstem? Hypothalamus? Telencephalon?
NE, dopamine, serotonin
Histamine containing neurons
Acetylcholine
NE neurons are found in the ___ ___ of the medulla and ___ ___ and VL medulla of the ___ pons.
solitary nucleus; locus ceruleus; rostral
NE neurons are found in the ___ ___ of the medulla and control memory enhancement. They are also found in the ___ ___ and VL medulla of the ___ pons.
solitary nucleus; locus ceruleus; rostral
T/F. The locus ceruleus controls pain regulation and the ventralateral medulla is involved in cortex (arousal) vigilance and attention, which is more active in attentive situations.
False, locus ceruleus = cortex (arousal) vigilance and attention, which is more active in attentive situations. Ventralateral medulla is involved in pain regulation via the spinal cord.
NE projections in the locus ceruleus innervate practically the entire CNS with heavy projections going to the ___ cortex.
somatosensory
Stimulation of the ___ ___ produces increased state of arousal. NE released in the ___ facilitates attention to that stimuli. NE released in the ___ ___ nucleus and spinal cord suppresses incoming ___ signals.
locus ceruleus; cortex; trigeminal spinal; pain
Patients suffering from clinical depression have decreased levels of what neurotransmitter?
NE
Depression and decreased ___ leads to reduced locus ceruleus activity. Patients suffering from ___ disease have lost neurons in the locus ceruleus and suffer from depression.
NE; Parkinson’s
Pain disorder is associated with what neurotransmitter?
increased levels of NE
Where can you find dopaminergic neurons in the midbrain?
substantia nigra (putman and caudate) and the ventral tegmental area (limbic system)
What are the two tracts of the ventral tegmental area?
mesolimbic and mesocortical
The ___ tract project fibers to the limbic system, specifically the nucleus ___ where there is a sense of reward and ___ dependency.
mesolimbic; accumbens; drug
The ___ tract sends fibers to the ___ cortex that organizes and initiates behavior.
mesocortical; frontal
What area is implicated in the development of disorganized thinking (frontal lobe) and hallucinations (limbic system) in patients suffering from schizophrenia?
ventral tegmental area
Social withdrawal in schizophrenic patients is due to ___ levels of dopamine in the ___ cortex. Hallucinations are caused by ___ levels of dopamine in the ___ system.
low; prefrontal; high; limbic
T/F. Drugs that lower the level of dopamine are effective in reducing hallucinations.
True.
Serotonergic neurons are located in all brainstem levels in the ___ nuclei. Projections are very extensive to ___ and ___ areas.
Raphe; sensory; limbic
How do serotonergic neurons of the raphe nuclei play a role in attention?
by inhibiting distracting stimuli
Which raphe nuclei plays a role in pain suppression?
nucleus raphe magnus
What type of serotonin drugs are given to depressed patients?
selective serotonin reuptake inhibitors (SSRI)
What do low levels of serotonin lead to?
- high carbohydrate consumption (obese women)
2. binge eating
What do high levels of serotonin lead to?
compulsive behavior and anorexia nervosa
Drugs that increase the level of serotonin are used to treat…
Depression
Anxiety
___ is a neurotransmitter of ___ neurons found in the basal forebrain and basal nucleus(of Meynert). It is also part of the RF in the ___ ___ ___.
Acetylcholine (ACh); dorsolateral pontine tegmentum
Damage to cholinergic neurons in the basal forebrain or basal nucleus lead to what disease?
Alzheimer disease
How do cholinesterase inhibitors work?
slow breakdown of ACh
