Reticular Formation Flashcards
(46 cards)
reticular formation “evolutionary age” and general functions
- phylogenetically old part of brainstem
- has over 100 loosely distributed nuclei that functionally link higher brain centers with the spinal cord, maintain vegetative functions and regulate states of arousal and consciousness
describe the architecture of the reticular formation
-the cytoarchitecture consists of large and small cells intermixed with bundles of ascending and descending myelinated fibers
how are the dendrites of the reticular formation oriented with respect to the neuroaxis?
-perpendicular
Describe the general afferents of the reticular formation
- ascending sensory information both visceral and somatic
- descending motor signals from the cortex, superior colliculus, and cerebellum
the main efferents of the reticular formation include
- spinal cord controlling/modulating: postural control, visceral motor, and crude voluntary motor
- cranial nerve nuclei (eye movements)
- cerebellum
- and thalamus
the reticular formation gains access to widespread areas of cortex via the ____ nuclei through which it can regulate conscious state.
-intralaminar thalamic nuclei
How do monoamine neurons in the reticular formation project to the cortex?
-directly!! No need to go through the thalamus
let’s play a game:
Neurotransmitter, location, effect
serotinin
- raphe nuclei
- mood
let’s play a game:
Neurotransmitter, location, effect
norepinephrine
- locus coeruleus
- vigilance and attention
let’s play a game:
Neurotransmitter, location, effect
acetylcholine
- pedunculopontine/laterodorsal tegmentum –> sleep/wake cycles and behavioral salience
- basal forebrain–> attention and memory
let’s play a game:
Neurotransmitter, location, effect
histamine
- tuberomammillary hypothalamus
- alertness
let’s play a game:
Neurotransmitter, location, effect
Dopamine
- ventral tegmental area
- motivated behavior and cognition
peptide containing cells in the lateral hypothalamic area
- widespread projections to cortex and thalamus and regulate arousal
- orexin and melanin-concentrating hormone
Experimental Investigation of Conscious State:
during the 1930’s-50s, researchers performed different brainstem lesions. Describe their methods and some of their results
-if they lesioned ONLY major ascending sensory pathways, but NOT the reticular formation than sleep-wakefulness was not disrupted
—-BUT—–
IF they lesioned the reticular formation, but not ascending sensory pathways they produced a permanent coma
describe a way to waken a sleeping animal
-stimulate the midbrain reticular formation
Reticular Activating System
-nickname of the reticular formation since it is necessary for maintaining conscious awake states
EEG
electroencephalogram was developed by Hans Berger in the 1920’s
- electrodes are placed on scalp and grounding position like the ear
- EEG records waves of electrical activity conducted from the cortex through the head; these reflect the activation of the cortex by the thalamus
The EEG represents ___ activity. When groups of cells fire in a ___ manner, they produce a large amplitude electrical signals
- summed
- synchronized
EEG: alpha waves
- Stage 1
- a person at rest with eyes closed
- cortical activity is described as being moderately synchronized in slow, small amplitude a waves
Beta waves
- when a person is alert and concentrating on a task
- these waves are describes as lower amplitude waves that occur with a higher frequency. these reflect desynchronized firing
The first definitive EEG sign of sleep state is the ___
sleep spindle. This occurs in stage 2
describe stage 4 EEG patterns
-amplitude of synchronous EEG increases dramatically while the frequency declines
Delta sleep (slow wave)
- occurs in stage 4
- the sleep is deep and the body exhibits low BP, low HR, and slow respirations
AFTER an episode of slow-wave sleep
- the EEG reflects an awake pattern called rapid eye movement (REM)
- this is paradoxical sleep
