Anatomical Basis of Neurological Pathways

Question 1

what are the brain’s major cholinergic neurons?

Answer 1

• nucleus basalis of meynert (NMB)
• pedunculo-pontine tegmental nucleus (PPPT/LDT)

Question 2

nucleus basalis of meynert (NBM)

• releases what NT?
• clinical significance?

Answer 2

releases ACh

• responsible for: conscious perception & cognition
• dysfunction leads to: Altzheimers

Question 3

pedunculo-pontine tegmental nucleus (PPD/LDT)

• releases what NT?
• clinical significance?

Answer 3

releases ACh

• responsible for: dreaming & muscle atonia in REM sleep
• dysfunction leads to: REM sleep disorders - acting out dreams erractically, violently

Question 4

what are the brains major histaminergic projections?

Answer 4

tuberulomamillary nucleus (TMN) in the hypothalamus

Question 5

tuberomamillary nucleus (TMN)

• releases what NT?
• clinical significance?

Answer 5

releases histamine (& projects to cholinergic nuclei)

• responsible for:
  
  • sleep modulation - arousal
  • metabolism - inc metabolism
• dysfunction:
  
  • hypoactivation:
    
    • sleepiness
    • high appetite -> obesity
  • hyperactiviation:
    
    • inability to sleep

Question 6

hypoactivation of the tuberomamillary nucleus leads to?

Answer 6

• increased sleep
• increased appetite, possibly obesity

Question 7

hyperacitivation of the tuberomamillary nucleus (TMN) leads to?

Answer 7

inability to sleep (too aroused)

Question 8

what are the major dopraminergic projections of the brain?

Answer 8

• ventral tegmental area (VTA)
• substantia nigra

Question 9

ventral tegmental area (VTA)

• releases what NTs?
• clinical significance?

Answer 9

releases dopamine

• various responsibilities through different projections.
  
  • mesocortical: executive function
  • mesolimbic: reward
  • tubuloinfundibular: regulation of PRL secretion
• dsyfunction of each :
  
  • mesocortial: hypofunction -> negative sx of schizophrenia
  • mesolimbic: hyperfunction -> positive sx of schizophrenia
  • tuberuloinfundibular: hyperprolactinemia

Question 10

the substantia nigra

• releases which NT?
• clinical significance?

Answer 10

releases dopamine

• via the mesostriatal projection:
  
  • responsible for: coordinating movement
  • dysfunction leads to: parkinsons

Question 11

list the dysfunction causing each presentation

• Negative symptoms of Schizophrenia
• Positive symptoms of Schizophrenia
• Parkinson’s Disease
• Hyperprolactinemia

Answer 11

• hypofunctioning mescortical projection of VTA
• hyperfunctioning mesolimbic projection of VTA
• hypofunctioning mesostrial projection of STN
• dysfunctioning tuboinfundibular projection of VTA

Question 12

what are the major noreadrenergic projections of the brain?

Answer 12

locus coeruleus (“blue spot”)

Question 13

locus coerulus

• releases what NTs?
• clinical significance?

Answer 13

release a1, a2, and B2

• responsibilities:
  
  • cortex & thalamus: attention / focus
  • limbic system: feat / anxiety
  • hypothalamus: sleepiness - inhibits inhibitors of VLPO
• defects:
  
  • cortex & thalamus: hypoarousal -> ADHD, hyperarousal -> anxiety
  • limbic system: hyperaousal -> mania, stress, PSTD
  • hypothalamus: hyperarousal -> sleeeplessness

Question 14

damage of the locus coeruleus neurons that project to the cortex & thalamus will lead to?

why?

Answer 14

• ADHD - with hypoarousal
• anxiety - with hyperarousal

this projection is responsible for attention & focus

Question 15

damage of the locus coeruleus neurons that project to the limbic system will lead to?

why?

Answer 15

mania, stress, and PTSD (with hyperarousal)

this projection is responsible for fear & anxiety

Question 16

damage of the locus coeruleus neurons that project to the hypothalamus will lead to?

why?

Answer 16

hyper = sleepless, hypo = sleepy

these projects release a2 (inhibitory) onto VLPO, inhibiting sleep induction

Question 17

what are the serotonergic neurons of the brain?

Answer 17

the raphe nucleus - rostral, dorsal, median

Question 18

the raphe nuclei

• releases what NT
• clinical significance?

Answer 18

releases serotonin (5-HT)

• responsible for: mood, sleep, anxiety
• dysfunction: hypoactivation of each projection
  
  • ​to amygdala: sadness*
  • to hypothalamus: appetite changes - too high or too low
  • pituitary: menstrual, sleep disturbances

Question 19

damage to which nuclei can can cause appetite disturbances?

Answer 19

• tubulomamillary nucleus (histaminergic) - hypoactivation -> overeating
• raphe nuclei (serotogenic) projecting to hypothalamus -> overeating or anorexia

Question 20

clinical significance of orexinergic neurons

Answer 20

• role: maintaining proper vigilance
• dysfunction leads to:
  
  • primary hypersomnia
  • narcolepsy
  • cataplexy - sudden loss in muscle tone

Question 21

clinical significance of VLPO receptors

Answer 21

• induce sleep via GABA release
• lesions / damage lead to insomnia

Question 22

dysfunction of what key nuclei can lead to sleep disturbance?

Answer 22

• REM sleep dsfyunction (acting out dreams): PPT (cholinergic)
• sleepiness: hypoactivation of tubulomamillary (histaminergic), locus coerulus (adrenergic)
• sleeplessneess: hyperactivation of tubulomamillary (histaminergic), locus coerulus (adrenergic)
• narcolepsy / cataplexy: orexinergic

Question 23

which three neurotransmitters are ALL

• increased in excitement
• decreased in depression

Answer 23

• NE
• dopamine
• 5-HT (serotonin)

Question 24

how do caffeine & alcohol afect GABA and glutamate?

Answer 24

• Caffeine: suppresses GABA, but stimulates glutamate
• Alcohol: stimulates GABA, but suppresses glutamate.

Question 25

alchohol increases / decreases release of which NTs? to have which effects?

Answer 25

activation * GABA - sedation * NE - stimulation * DA - addiction / pleasure inhibition * Glu- **slurred speech & memory disruption**

Question 26

nicotine increases ./ decreases release of which NTs? to have which effects?

Answer 26

all activation * cholinergic - energizes * dopraminergic - addiction * glutamergic - desire to use nicotine

Question 27

dysfunction of which neurons can lead to mania?

Answer 27

loculus colerulus (adrenergic) limbic projection hyperactivation

Question 28

dysfunction of what neurons can lead to ADHD?

Answer 28

locus colerulus (adrenergic) cortical / thalamic projections hypoactivation