Neurophysiology of Drug Addiction (Karius) Flashcards
in producing pleasure, the VTA sends increased amounts of this NT to the Nac..
Increased dopamine
the core of the reward/pleasure system consists of these 2 areas..
Ventral segmental area (VTA) Nucleus accumbens (NA)
the VTA receives excitatory input from these 3 areas…
pre-frontal cortex
Lateral hypothalamus
laterodorsal tegmental nucleus
the prefrontal cortex, laterodorsal tegmental nucleus, and lateral hypothalamus provide excitatory input to the VTA via these NTs…
prefrontal cortex: EAA
Lateral hypothalamus: Orexin
laterodorsal tegmental n.: Ach
the VTA provides a dopamnergic input to the NAc via the __
median forebrain bundle
in addition to the dopaminergic VTA input, the NAc also receives EAA from these areas…
Prefrontal cortex
Amygdala
hippocampus
output from the NAc is to the pre-frontal cortex via this NT…
GABA
NAc also sends a GABA-ergic input back to the VTA
opioid inputs to the VTA inhibit a subset of GABA-ergic interneurons. This increases the release of __ in the NAc
Dopamine
___-receives inputs and releases dopamine in the NAc to lead to feeling of pleasure
VTA
___-part of striatum. D1- activate direct; D3- inhibit indirect pathways. When active, GABA is released to produce pleasure
NAc
___-receives input allowing pleasure from NAc
Pre-frontal cortex
Outline the Core system pathway of producing Pleasure …
Prefrontal cortex, Laterodorsal tegmental nucleus release increased EAAs & Lateral hypothalamic nucleus releases increased Orexin onto VTA —> VTA releases increased amounts of Dopamine onto NAc —> NAc decreases GABA release onto Pre-frontal cortex –> Pleasure
Outline the pathway for Preventing/absence of pleasure..
Prefrontal cortex, amygdala, and Hippocampus release increased amounts of EAA onto NAc –> NAc releases increased amount of GABA onto prefrontal cortex –> Absence of pleasure
The pleasure/reward system is what type of feedback system?
positive feedback
which D receptors are inhibitory?
D2 and D3
Major action of opioids in the reward/pleasure system?
Inhibit GABA interneuron in VTA –> VTA releases more dopamine in NAc –> intense feeling of pleasure (euphoria)
To produce pleasure, what happens to the following?
VTA=__
NAc=__
GABA in the prefrontal cortex=__
Activate the VTA
Inhibit the NAc
Less GABA in prefrontal cortex
To inhibit pleasure, what happens to the following?
NAc=___
GABA in the prefrontal cortex=___
Activate the NAc
More GABA in prefrontal cortex
___=changes in the anatomy and physiology of synapses associated with learning. Some changes are permanent, others more transient
Synaptic plasticity
___=Increase in response to same stimulus. Changes in both pre- and post-synaptic neurons which include increased NT release and increased post-synaptic responses d/t changes in the receptors to which NT binds
Long-term potentiation
What drugs work by activation of GPCRs?
Opiates=agonist at opioid receptors
Cannabis=CB-1 receptor, leads to DA release
What drugs work by alteration of ion channels?
Nicotine=agonist at NAChRs, influx of Na
Ethanol/PCP=Anatagonist at NMDA receptors (weak)
What drugs work by interference with re-uptake mechanisms?
Cocaine=Inhibition of re-uptake of DA –> increase in DA availability at synapse
Amphetamines=reversal of DA reuptake transporters
Ethanol activates the opioid inputs, particularly to the __
VTA
