Reticular system Flashcards
What are the functions of the reticular systyem?
Integrates information from all senses
Consciousness and arousal
Filters unimportant information, shunts life-threatening information to the amygdala
What are the three columns of the reticular system?
Lateral
Medial
Median
What is the lateral column?
Contains small, parvicellular neruons that receive afferent fibers from neighboring brainstem regions
What is the medial column?
Contains magnocellular and gigantocellular neurons that give rise to many efferents
What is the median column?
Contains intermediate sized serotonin neurons of th raphe nuclei
What is the nucleus basalis of Meynert or the basalis magnocellularis?
Located in the telencephalon
Contains ACh neurons that project widely to the cortex and amygdala
Plays a role in selective attention, alerness and memor processes
What is the reticular nucleus of the thalamus?
Diencephalon
Receives input from other thalamic nuclei and widespread cortical area
Influences cortex via other thalamic nuclei
What is the periaqueductal grey?
MIdbrain
Grey matter that surrounds the cerebral aqueduct
Involved in modulating descending pain pathway, contains high density of opioid receptors
What is the dorsal raphe nucleus?
Midbrain
Primary site of serotonergic neurons in the reticular formation
Widespread forebrain connections with now thalamic relay
Regulation of consciousness, attention, and mood
What is the ventral tegmental area?
Midbrain
Part of the mesolimbic dopamine and mesocortical DA reward pathways
Plays a role in memory, attention, and motivation
What is the substantia nigra pars compacta?
Midbrain
Part of the nigrostriatal pathway
Basal ganglia function
Also may play a role in reward and reinforcement
What is the Nucleus locus coeruleus (blue nucleus)?
Pons
Provides the majority of NE input to the CNS
Modulate arousal, selective attention, stress response, pain, and mood
What is the Pedunculo-pontine nucleus and laterodorsal tegmental nucleus?
Pons
Largest sites of ACh production in the brain
Involved in wakefulness and REM sleep
Part of the indirect arousal system that must be inhibited for sleep to occur
What is the Nucleus raphe magnus?
Medulla
Contains serotonergic neurons
Involved in modulating pain transmission
What is the rostral ventral medulla nucleus?
Medulla
Contains glutamatergic neurons
Involved in modulating the transmission of pain within the CNS, similar to the PAG
What are the nuclei of the medullary reticular formation?
Medulla
Critical in cardiovascular and respiratory center regulation
What is responsible for actively maintaining consciousness/wakefulness/arousal/attention?
Ascending reticular activating system
What are the functions of the RAS?
Consciousness
Filter out massive amounts of information
Primes the cortex to allow incoming sensory information to be processed
Shunts fearful information to the amygdala
What are the two most well known pathways in the ARAS?
Aminergic nuclei
Cholinergic nuclei
What are the aminergic nuclei in the ARAS?
Nucleus locos coeruleus, raphe in the midbrain, Tubermammilary nucleus in the hypothalamus
activated exclusively during the waking state
What are the Cholinergic nuclei in the ARAS?
Pedunculo-pontine, Laterodorsal tegmental nuclei
Activated during waking state and REM sleep
What is locked-in syndrome?
Lesion preventing corticospinal and corticobulbar motor output
Sensory function and consciousness is preserved
What is akinetic mutism, abulia, or catatonia?
Ipaired frontal and dopaminergic function leading to profound apathy and deficits in response initiation
What is a minimally conscious state?
Periods of responsiveness or wakefulness with minimal and variable awareness
What is a vegetative state?
Consists of periods of wakefulness, but no periods of awareness
No visual tracking, no volitional behavior
What is a persistent vegetative state?
Vegetative state that lasts for more than a month without evidence of change
What is a coma?
Prolonged losss of consciousness with a severe impairment of corical function
Unresponsive to sensory input but some primitive reflex activity can be present
What is brain death?
Irreversible unconsciousness with complete loss of brain function and inability to breath
What are some causes of comas?
Bilateral lesion in upper brainstem affecting RAS
Bilateral compromis of the hemispheres
Large bilateral lesion of the thalamus
What are the 4 major dopamine pathways in the brain?
Substantia nigra to the neostriatum
Ventral tegmental area to the nucleus accumbens - reward, + schizo symptoms
VTA to the cortex - parkinsons and - schizo symptoms
Tubero-infundibular projection - arcuate nucleus to the anterior pituitary
What are typical anti-psychotic drugs?
Alliviate the positive symptoms of schizophrenia, but exacerbate the negative symptoms
can also cause hyperkinetic affects
What are atypical anti-pyschotic drugs?
Cause fewer extrapyramidal effect but come with the complication of weight gain, T2DM, and prolactinema
What is the major norepinephrine pathway in the brain?
Nucleus locus coeruleus, widespread projections to the cortex, limbic system and dorsal horn
Modulate arousal, selective attention, pain modulation
What are the two important serotonin nuclei?
Dorsal raphe nucleus - mood modulation
Nucleus raphe magnus - modulation of pain transmission
What is the major acetylcholine nuclei in the brain?
Nucleus basalis of Meynert
Diffuse projections to the cortex without relaying through the thalamus
