Lecture 3: Addiction

Question 1

Name the core features of addiction according to the DSM-5.

Answer 1

• A compulsive pattern of drug-seeking & -taking behavior
• At the expense of most other activities
• Despite possible negative consequences
• Hard to stop using and high risk of relapse

Question 2

Describe the classic experiment by James Olds (1954).

Answer 2

Olds placed electrodes in the brain’s reward area of mice. The electrodes became active and stimulated the brain area when the mice pressed a lever in their cage. As a result, the mice kept on pressing the lever over and over again, ignoring all their other needs (e.g. eating and drinking).

Question 3

Which neurotransmitter is particularly important in addiction?

Answer 3

Dopamine.

Question 4

Describe the neuronal mechanisms of cocaine and heroine regarding their influence on signal transmission.

Answer 4

Heroin and Cocaine both increase dopamine but in different ways:

GABA neurons normally inhibit dopamine neurons.
Heroin inhibits GABA neuron, leading to disinhibition and more dopamine.

Cocaine (Meth, crack, …) directly act on dopamine neurons: Block dopamine reuptake by blocking transporters

Question 5

How do opiates (and other drugs) alter the morphology of neurons in the reward circuit?

Answer 5

Dendrites of the neurons degenerate, while at the same time the use-dependent plasticity leads to sensitized responses to drug and environmental cues.

Question 6

How does drug addiction change brain areas (e.g. amygdala and PFC)?

Answer 6

The amygdala in addicted individuals shows higher activation when drug-related stimuli are presented (compared to healthy controls). The PFC shows reduced activation in addiction. In the striatum there is less D2 receptor availability in reaction to drug intake compared to controls.

Question 7

Describe the optogenetic approach and its advantages over stimulation with electrodes.

Answer 7

In optogenetics, genes encoding for light-sensitive proteins are changed. Then these proteins are brought into the neurons of interest. Shining light of a specific wavelength on the neuron will then either excite or inhibit it. Due to this property, optogenetics have the advantage of influencing neuronal activity more specifically as well as offering the option of inhibiting a neuron. With the standard electrode stimulation approach, neither of this is possible.

Question 8

Which cognitive functions are particularly involved in addiction?

Answer 8

Attention, behavioral flexibility, decision-making, inhibitory control, planning, time estimation and working memory.

Question 9

Which personality characteristic / cognitive dysfunction is a strong predictor for addiction?

Answer 9

Impulsivity.