Reticular Formation

Question 1

what is RF?

Answer 1

continuous network of nerve cells and fibers that extend through the neurosis from the SC to the cerebral cortex

it is strategically placed amount the nerve tracts and nuclei so that it receives input from most sensory systems

it has efferent projects that decent and ascend to all levels of the CNS

(everything that goes up and down will send collaterals into the RF)

Question 2

what are the general functions of the RF?

Answer 2

control of skeletal muscle -regulation of the motor system

control of somatic and visceral sensation

• pain modulation
• gating role

cortical activation

• ARAS (with control of somatic sensation)
• -> focusing of attention, habituation

Control of ANS- regulation of visceral activity
-respiration, cardiac function, vasomotor tone, reflexes, etc

Control of endocrine NS with hypothalamus
-influence on biological clocks

?sleep (esp non REM)

(pons controlls the bladder; medulla the heart)

Question 3

what is the general arrangement of non-cerebellar RF?

Answer 3

3 longitudinal columns:

1-median

• Raphe nucleus - serotonin (pain modulation)
• intermediate size

2- medial

• efferent system
• large size (gigantocellular)

3- lateral

• afferent system
• small size (parvocellular)

Question 4

what is the general arrangement of the pre-cerebellar RF?

Answer 4

pontine reticulotegmental

paramedian reticular

lateral reticular

• parvicellular- somatosensory-vermis
• magnocellular-cortex-cerebellar hemispheres

Question 5

what is the function of serotonin? where is it?

Answer 5

where: dorsal and median raphe nuclei
throughout BS, SC, cerebral cortex, cerebrum

neurochemicals made in RF

mood
aggression
memory processing
sleep
cognition
foot intake
pain modulation

Question 6

what is dopamine? where is it produced?

Answer 6

neuromodulator that affects how things work, but doesn’t stimulate anything itself

Substantia nigra:

• striatum
• facilitate voluntary movement

Ventral tegmental area:

• involved in reward system
• somehow assigns value to, or reinforces, certain adaptive behaviors

no dopamine=no motivation, depression

dopamine assigns value to what you are doing, reinforces it (issue- might not do the right thing all the time)

Question 7

what is norepinephrine? functions? where?

Answer 7

locus coeruleus-most prominent area

pontine and medullary groups

functions:
-regulation of attention, arousal, sleep/wake cycles, learning, memory, anxiety, pain, mood, and brain metabolism

seems to turn on by new, unexpected, non-painful sensory stimuli

too much= hyper anxious, anxiety issues, insomnia, don’t go into non-REM sleep

Question 8

what is acetylcholine?

Answer 8

pedunculopontine nucleus

ACh receptors:

• iontotrophic- nicotinic
• metabotropic- muscarinic

basal forebrain complex

• medial septal nuclei
• basal nuclei of Meynert- medial and ventral to BG
• supplies neocortex

pontomesencephalotegmental comples- pedunculopontine nucleus

• acts on dorsal thalamus
• both assist in the regulation of the excitability of sensory relay neurons and ARAs

promotes arousal in the brain; short and long term
causes membranes to act different, drive brain

Question 9

what is histamine?

Answer 9

comes from hypothalamus (tubermamillary nucleus)

important in sleep-wake cycle, keeps cerebellum awake

goes up central segmental bundle

activator

Question 10

what are the 6 major efferent connections of the RF?

Answer 10

1- limbic forebrain- important for memory, emotion, attention seeking, homeostasis

2- cerebellum- muscle tone and coordination of movement

3- brain stem autonomic centers- nucleus solitaries

4- multiple brainstem regions for set-point modulation

• SC sensory
• SC autonomic
• SC motor control-actual movement

5- nucleus of the solitary tract

6- RF- always projects to itself- ascending reticular activating system