5 Single-source/ Divergent Networks Flashcards
What are do defects in NT amines and acetylcholine often result in?
psychiatric disorders
What are the amine NTs?
Dopamine
Norepinephrine/Epinephrine
Histamine
Serotonin
What is another important NT that is not considered an amine?
Acetylcholine (ACh)
What are the 5 single-source divergent networks?
- Dopamine (DA)
- Norepinephrine (noradrenaline/adrenaline)(NE/NA)/ Epinephrine (Epi)
- Histamine (His)
- Serotonin (5-HT/ 5-HTP)
- Acetylcholine (ACh)
What do all of the 5 networks utilize?
unique NTs
- Small molecule NTs
- Ca dependent release
Where are the neurons that release a single NT contained?
in nuclei
What are the locations of the 5 network nuclei?
Brainstem, hypothalamus and basal forebrain
Network neurons in the 5 single-source divergent networks have what characteristics?
unmyelinated axons that are highly arborized which synapse on many target cells in various brain regions
Do all 5 networks communicate?
Yes, they are interconnected and work cooperatively together to control overall brain state
- consciousness, attention, emotion, learning and memory processes, and the monitoring of overall physiologic state of the body
What other brain regions do the 5 networks also project to?
thalamus and cortical regions
List of nuclei and systems on pg 19
better visualized on pg. 20 (if you went to class to fill it in)
Volume synaptic transmission is what type of synapse?
Non-direct synapse
How does volume synaptic transmission work?
Release of NT in response to intracellular Ca, through varicosities of the axons –> NT can diffuse freely
Numerous NT molecules can diffuse freely in various directions is known as what type of release?
Omnidirectional
What are postsynaptic physiological effects via “volume synaptic transmission” NT release?`
- Large numbers of cells influenced each time NT released
- Long duration of modulatory effects
- Non-directed action
Which pathway of the brain is involved in producing the state of consciousness (during the sleep-wake cycle)?
Thalamic ascending reticular activating system (ARAS, RAS
What structures (nuclei) do the circuits of the ARAS/RAS ascend through in the brainstem and cerebral cortex?
- Intralaminar thalamic nuclei (ILn)
- Thalamic reticular nucleus (TRn) of the thalamus to cerebral cortex
What do all 5 of the single-source divergent networks communicate with?
the thalamic ARAS
Where is the norepinephrine/noradrenaline produced?
Locus coeruleus (Lc) - a paired brainstem nuclei within the rostral pons
Where in the brain does the Locus coerules (Lc) of NE/NA system project?
Several regions including the cerebrum, hippocampus, cerebellum, and the hypothalamus
- Even to structures of the limbic system (amygdala)
- Also to ARAS
Functions of the NE/NA system?
- Excitatory and Inhibitory
- Attention and arousal (including “flight or flight” response)
- Negative emotion process
- Regulation of deep sleep (non-REM sleep)
- Support learning and memory
- May aid in cognitive performance
What is the source of histamine in the CNS?
tuberomammilary nucleus (TMn) of the hypothalamus
Is histamine excitatory, inhibitory, or both?
only excitatory
What are the targets of the His system?
brainstem, spinal cord, hippocampus, thalamus, cerebellum, and cerebrum
What are the functions of the His?
- Mediation of arousal and attention
- Modulation of body energy stores (energy homeostasis)
- Control of circadian rhythms
- Support learning and memory
Where is the serotonin (5-HT) produced?
Raphe nuclei
Where is the Raphe nuclei located?
A region of the brainstem that extends from the pons to the midbrain
Does serotonin have an excitatory or inhibitory affect?
both
Where do the projections from the Raphe nuclei in the serotonin system go?
to the cerebellum, brainstem, spinal cord, thalamus, hypothalamus, and cerebrum
What are the functions of serotonin system?
- Mediation of attention & arousal
- Inhibition (suppression) of behavior
- Modulation of negative emotions
- Support learning & memory
- Control of deep sleep (non-REM)
Of the 8 distinct nuclei of the Ach system, which two are considered the principle nuclei?
Basalis of Meynert (NB) and Pontopeduncular nucleus (PPN)
Where is the Basalis of Meynert (NB) located?
anterior part of the thalamus and lenticular nucleus within the anterior perforated substance
Where is the pontopeduncular nucleus (PPN) located?
in the midbrain adjacent to the substantia nigra
Is ACh excitatory or inhibitory?
Excitatory only at the NMJ, but both in the brain
Brain regions that receive input from ACh neurons
thalamus, hypothalamus, hippocampus, and cerebrum
Where specifically are nuclei of the Dopamine (DA) system?
Nuclei of the ventral tegmental area (VTA) and Substantia nigra
Functions of the dopamine system?
- Mediate the brain’s “positive reward network” & motivation
- Modulates positive emotion and mood
- Supports learning and memory
- Mediates attention and arousal
How is dopamine removed from the synaptic cleft?
through enzymatic breakdown and cell uptake/re-uptake
What is the is the dopamine transporter referred to as?
DAT
What do opiate drugs like cocaine and amphetamines do to dopamine and its receptors?
they block re-uptake of dopamine by binding to the DAT r/c
- this increase release of more dopamine
- Some also activate Ca channels –> releasing large bolus of dopamine in to synapse
T/F: Opiates can block GABA-ergic inhibitory interneurons.
True
What is the role of Nicotine in the DA system?
Binds to a subtype of GLU r/c (nicotinic r/c)
- Binding on these excitatory neurons results in release of GLU
What is the role of GLU in the DA system and nicotinic r/c?
GLU binds to the VTA neurons, activating and causing the release of dopamine (DA)
What types of feelings and emotions are activated with activation of the DA system?
Positive feelings and emotions
- more often the pathway is stimulated, the stronger the motivational drive
