Reticular Formation Flashcards Preview

Functional Neuranatomy > Reticular Formation > Flashcards

Flashcards in Reticular Formation Deck (46):
1

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

2

describe the architecture of the reticular formation

-the cytoarchitecture consists of large and small cells intermixed with bundles of ascending and descending myelinated fibers

3

how are the dendrites of the reticular formation oriented with respect to the neuroaxis?

-perpendicular

4

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

5

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

6

the reticular formation gains access to widespread areas of cortex via the ____ nuclei through which it can regulate conscious state.

-intralaminar thalamic nuclei

7

How do monoamine neurons in the reticular formation project to the cortex?

-directly!! No need to go through the thalamus

8

let's play a game:
Neurotransmitter, location, effect
serotinin

-raphe nuclei
-mood

9

let's play a game:
Neurotransmitter, location, effect
norepinephrine

-locus coeruleus
-vigilance and attention

10

let's play a game:
Neurotransmitter, location, effect
acetylcholine

-pedunculopontine/laterodorsal tegmentum --> sleep/wake cycles and behavioral salience

-basal forebrain--> attention and memory

11

let's play a game:
Neurotransmitter, location, effect

histamine

-tuberomammillary hypothalamus
-alertness

12

let's play a game:
Neurotransmitter, location, effect

Dopamine

-ventral tegmental area
-motivated behavior and cognition

13

peptide containing cells in the lateral hypothalamic area

-widespread projections to cortex and thalamus and regulate arousal
-orexin and melanin-concentrating hormone

14

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

15

describe a way to waken a sleeping animal

-stimulate the midbrain reticular formation

16

Reticular Activating System

-nickname of the reticular formation since it is necessary for maintaining conscious awake states

17

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

18

The EEG represents ___ activity. When groups of cells fire in a ___ manner, they produce a large amplitude electrical signals

-summed
-synchronized

19

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

20

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

21

The first definitive EEG sign of sleep state is the ___

sleep spindle. This occurs in stage 2

22

describe stage 4 EEG patterns

-amplitude of synchronous EEG increases dramatically while the frequency declines

23

Delta sleep (slow wave)

-occurs in stage 4
-the sleep is deep and the body exhibits low BP, low HR, and slow respirations

24

AFTER an episode of slow-wave sleep

-the EEG reflects an awake pattern called rapid eye movement (REM)
-this is paradoxical sleep

25

describe the physiological events associated with REM sleep

-EMG will show muscle atonia
-EOG shows rapid eye twitches
-increased BP, HR, respiration, and the brain will consume more O2

** most dreaming occurs during REM :)

26

Animals and humans will die if __ sleep is prevented

REM
-within 12-16 days for humans

27

What are the causes of death in animals that have been deprived of sleep?

-autonomic and immune system failures
-disrupted weight control, body temp, and cardiovascular function and sepsis secondary to immunodeficiency

28

REM rebound

-since REM is the most crucial component of sleep a person who is deprived of REM sleep one night will spend double the time in REM the following night

29

Newer research indicates that sleep is necessary for

-optimum removal of brain metabolites and contaminant s
-this happens thanks to an increase in interstitial space and a greater perfusion of brain tissue by CSF

30

Through its diffuse projections to the intralaminar nuclei, the ____ RF is positioned to control conscious states

-mesencephalic

31

In the ALERT state, the excitatory projections of the MRF to the intralaminar nuclei cause thalamic and cortical activity to _____

-desynchronize

32

Under what conditions can the thalamus and cortex process meaningful sensory information

-alert state
-excitatory projections of the MRF to the intralaminar nuclei cause the thalamic and cortical activity to desynchronize

33

When a person enters sleep, cells of the ___ begin to slow down. A process which is facilitated by reducing sensory input. As the __ drive to the ___ circuitry falls below a certain threshold, the thalamic and cortical cells begin to fire in a ___, oscillatory manner

-mesencephalic RF (MRF)
-MRF
-thalamocortical
-synchronized

34

As a person falls asleep, the termination in the EEG peak is due to inhibition from the ___

-reticular thalamus

35

The onset of non-REM sleep is correlated with increased activity in the

-ventrolateral preoptic area of the hypothalamus
-these are GABA neurons

36

Stimulation of the VLPO induces ___ in animals

sleep

37

VLPO cells project to the:

-histamine cells in the tuberomammillary hypothalamus
-orexin neurons in the lateral hypothalamic area
-cholinergic cells in the PPT/LDT
-norepinephrine cells in the locus coeruleus
-serotonin cells in the raphe nuclei

38

lesions of the tuberomammillary hypothalamus histamine cells leads to

-somnolence
-this is why anti-histamine drugs can make one sleepy

39

Brainstem cholinergic cells are known to fire before EEG evidence of REM. This activation _____ the _____ and prevents rhythmic firing of thalamocortical circuits. This leads to the EEG becoming ____

-depolarized the thalamus
-desynchronized

40

Timing trigger

-talking about the REM timing trigger
-thought to lie at the midbrain-pons junction

41

What accounts for the muscle atonia during REM

-result of the inhibition of motor neurons

42

Describe the circuit for inhibition of motor neurons during REM

-Glutamate neurons in the sublaterodorsal nucleus of the pons are activated by cholinergic PPT/LDT. The SLD neurons project directly to the spinal cord and indirectly to glutamate neurons in the supraolivary medulla which also project to the spinal cord!
-the glutamate projections activate GABA/glycine interneurons in the spinal cord that then inhibit motor neurons

43

REM behavior disorders

-can occur from lesions in the pons or medulla which would release the motor inhibition during REM
-Humans with this lesion will act out their dream

44

Patients with narcolepsy have

-excessive daytime sleepiness suggesting REM intrusion into the wake cycle
-cataplexy (loss of muscle tone) suggestion intrusion of REM atonia into then wake cycle
-hypnagogic and hypnopompic hallucinations at sleep onset and offset, respectively

45

Sleep paralysis

-represents the inappropriate intrusion of cortical sensory processing and consciousness into the REM sleep state
-people suddenly become aware of muscle atonia and are unable to move despite sending urgent motor commands

46

a strain of Dobermans suffer from narcolepsy because of a mutation in the gene coding for

orexin receptor