Anatomical Basis of Neurochemical pathway Flashcards
Where are the ACh releasing neuron cell body aggregates?
basal forebrain
pontine tegmentum
ACh acts via what receptor types in the brain?
- Nicotinic:
- N2R - common in the brain
- Muscarinic:
- M1+3,5 - excitatory
- M2,4 - inhibit
What are the cholinergic nuclei?
- Basal forebrain
- Nucleus basalis of meynert (NBM)
- Medial septal nucleus & nucleus of diagonal band of Broca (MS, DBB)
- Pontine tegmentum
- Pedunculo-Pontine Tegmental Nucleus & Lateal Dorsal Tegmental Nucleus (PPT/LDT)
NBM sends fibers to what cortex? Is associated with what functions?
What receptors are located here?
neocortex: conscious perception & cognition (M1R)
MS, DBB sends fibers to what cortex? Is associated with what functions?
What receptors are located here?
hippocampus: learning (decreases in aging)
M1,3,4R
Degeneration of neurons in the NBM leads to what condition?
Decreased firing?
Alzheimer’s disease
decreased firing may result in visual hallucinations
PPT/LDT sends fibers to what cortex? Is associated with what functions?
What receptors are located here?
spinal cord & thalamus -> cortex : musle atonia & deams during REM sleep
M1,3,4R
Cortical activity initiated in REM sleep by what kind of waves?
PGO
Damage to PPT/LDT projections lead to what conditions?
- REM sleep disorders
- acting out dreams (loss of muscle atonia)
- dreamles sleep or severe dream enactment behaviors
What is the histamine releasing nucleus?
This has what physiological significance?
TuberMammillary Nucleus (TMN)
calm wakefulness
Histamine acts via what receptors in the brain?
Which one is unique?
- H1,2,3,4R
- presynaptic H3 is auto-receptor for negative feedback mechanism
TMN sends fibers where? Is associated with what functions?
What receptors are located here?
- highest density to hypothalamus (H1R) : metabolic regulation
- cerebral cortex & cholinergic nuclei: H1R
- thalamus: H1R ; H2R
- hippocampus, amygdala, striatum, cerebellum
Hypoactivation of histaminergic projections can lead to what clinical situations?
- increased leep
- abnormal appetites for food
- typically suppressess appetite -> w/ hypoactivation -> increased appetite -> obesity
Hyperactivation of histaminergic projections can lead to what problems? This can occur in what clinical situations?
- inability to sleep
- night terrors
- ABNORMALLY high
- brain tumors & psychosis
What are the appropriate relative histamine levels while awake, slow wave sleep & REM sleep?
- awake
- ++
- slow wave
- +
- REM
- 0
What substances are synthesized from tyrosine?
catecholamines
dopamine, NE
What substances are synthesized from tryptophan?
indolamines
serotonin, melanin
What are the major aggregations of domamine secreting neurons?
Physiologic actions?
(Midbrain)
Ventral Tegmental Area (VTA) : motication, reward mechanism
Substantia nigra: motor control
Dopaminergic fibers go where? They are associated with what functions?
- VTA
- mesocortical- cognition
- mesolimbic- emotion, reward
- Substantia nigra
- mesotriatal- movement
- Tuberinfundibular- prolactin
Damage to the dopaminergic projections can lead to what pathologies?
- mesocortical
- negative symptoms - schizophrenia
- mesolimbic
- positive symptoms - schizophrenia
- mesostriatal
- parkinosn’s disease
- tuberinfundibular
- hyperprolactinemia
Axons in the mesocoritcal projection go where?
Function?
Result of hypofunction?
VTA to prefrontal cortex
cognition & executive function
hypofunction - negative schitzophrenia symptoms