07 | Addiction Flashcards by Airi -

The reward pathway is also known as ___. It is made up of…

cortical limbic system pathway

2. VTA-NAc-FC

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Major sources of DA in the brain

VTA (reward)

2. SN (voluntary movement)

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Effect of opioids on DA

inhibit GABA ⇒ ↓ inhibition of DA release ⇒ more DA

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Effect of nicotine on DA

↑ dopaminergic innervation

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Effect of cocaine, amphetamines on DA

↑ DA release, ↓ DAT ⇒ more dopaminergic innervation

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Neuron composition of VTA

60% DA

40% GABA

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DA on NAc has what effect?

reward & reinforcement

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DA on PFC has what effect?

exclusive function (loss of control)

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DA on hippocampus has what effect?

memory

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DA on amygdala has what effect?

emotions

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What 2 things are needed for withdrawal response?

Stress

2. DA

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What was the experimental procedure that determined the relationship between stress and reward pathways? What was the result?

double labelling + in situ hybridization

In drug users, neuroadaptation of VTA DA neurons lead them to express CRF

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What happens to synaptic plasticity in drug addiction?

Promote LTP of dopamine (reward) pathways
Promote LTD of GABA (inhibitory) pathways
Loss of synaptic plasticity in NAc → linked to inability to control drug intake

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How does cocaine promote LTP in certain pathways? What is 1 short-term response?

↑ AMPA on VTA DA neurons⇒ stronger EPSP (LTP)

↑ dendritic spine density in VTA DA neurons ⇒ ↑ possibility of forming synapses (this is only for short-term response)

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Cocaine-induced LTP can be blocked by…

MK-801 (NMDA blocker)

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Which subunits of AMPA-R are not likely involved in LTP response to cocaine?

GluA1 and GluA2

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What eventually stops the ↑ AMPA LTP response?

mGluR1 (Ro 67)

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What is Ro 67?

mGluR1 activator

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LTP response is _synaptic, while LTD is _synaptic

2. post

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2 ways to induce LTD at VTA GABA-DA synapses

2. Morphine

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Mechanism used by LFS to cause LTD

decrease number and conductance of GABA(A)-R

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Does LTD depend on NMDA-Rs?

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Actions of morphine to cause LTD

Prevent LFS-LTD

2. induces its own LTD (unclear)

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Drugs that can induce LTD

nicotine, morphine, cocaine, alcohol

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How can addictive behaviors be prevented (has to do with GABA)

increase GABA innervation

List 2 NMDA-R blockers

1. MK-801 | 2. APV

What is the "switch" between addicted and non-addicted states?

BDNF

What defines the sensitivity limits of sensory stimuli?

sensory receptors

Define: adequate stimulus

the specific stimulus that a receptor responds to best

Define: transduction

changing adequate stimulus to electrical signal (receptor potential)

Adequate stimulus is a property of the ___

receptor

Receptor potential is recognized by CNS by:

1. Anatomical position | 2. sensory ending

Area of brain that controls smell

olfactory cortex

area of brain that controls memories

temporal cortical region

Damage to temporal cortical region has what effect on smell?

Prevents identification of smells, but you can still smell things

Mammals have how many axons projecting to the olfactory bulb?

100 000

Mucus in the nasal cavity is __ thick and replaced every __ min.

50 um 10 min

Olfactory receptors are replaced every __ months. New receptors originate from __.

1-2 months basal cells in olfactory epithelium

What is the only area in the brain that generates new neurons throughout life?

Olfactory bulb

Zones in the olfactory epithelium are regulated by...

expression of different receptor genes

In rats, the olfactory epithelium rests on top of __

turbinates

The same zone in the olfactory epithelium projects to...

a single pair of medial & lateral glomeruli in the olfactory bulb

What is in the limbic system?

- amygdala - entorhinal cortex - hippocampus - subiculum

From the olfactory bulb, projections are made to...

1. Limbic system (motivation, emotion, memory) | 2. Thalamus & FC (recognition)

Which currents are responsible for olfactory conductance?

inward K current, odorant current (open non-selective cation channels)

The K current causes __ depolarization, but the odorant current causes __ depolarization

1. initial | 2. prolonged (2nd messenger)

Non-selective cation channels opened by odorant lets in __ > __ >> __

Ca > Na >> K

which G protein is associated with odorant receptors?

G(olf)

Mechanisms of G(olf)?

1. -> more AC -> more cAMP -> open non-selective cation channels -> more Ca 2. -> IP3 -> DAG -> release Ca from intracellular stores

What are the 2 mechanisms to cause depolarization in ORN?

1. Ca influx due to G(olf) | 2. Ca-gated Cl current

What is the disease when there is no smell or reduced smell?

Anosmia

Causes of anosmia

- head injury - virus - congenital - consequence of other disorder

3 compartments of the cochlea

1. Scala media 2. Scala vestibuli 3. Scala tympani

Composition of scala media

- Endolymph - High K, low Na, low Ca - Concentration is actively maintained

Composition of scala vestibuli

perilymph

Composition of scala tympani

- perilymph | - similar to CSF

What are the membranes found in the cochlea? What to they separate?

Reissner's membrane: media + vestibuli Basilar membrane: media + tympani

Inner layer of hair cells is responsible for ___ signals, and outer hair cells are responsible for ___ signals

1. afferent | 2. efferent

Hair cells sense vibration from ___ and ___ membranes

Basilar, tectorial

How to hair cells cause depolarization and signal propagation?

movement -> open tip links -> K influx from endolymph -> depolarization -> open v-gated Ca channels -> vesicle release

Which ways does hair cells bend to cause hyperpolarization/depolarization?

- toward kinocilium = depolarization | - away from kinocilium = hyperpolarization

What kind of specialized synapse does hair cells have? Which NT is used?

- Ribbon synapse | - Glu

What # is the auditory nerve?

VIII

What is the pathway after nerve VIII?

nerve VIII -> medulla -> inferior colliculus (midbrain) -> medial geniculate nucleus (thalamus) -> auditory cortex

Which lobe is the auditory cortex located in?

temporal

Explain electromotility

depolarization cause hair cells to shorten, while hyperpolarization cause hair cells to lengthen. Movement of the hair cells also contribute to vibrations.

Electromotility is mediated by...

prestin (v-dependent motor protein that is coupled to the exoskeleton)

Tonotropic organization of auditory neurons

Different neurons in the auditory cortex responds to different frequencies

___ is the frequency that a neuron responds best to

characteristic frequency

07 | Addiction Flashcards

(69 cards)