Drugs and the brainFrans Koopmans, MADe Hoop Foundation

Drugs and the brain

The Brain• The brain is highly organized into a

number of different regions with specialized functions

• Hindbrain (maintenance of life: breathing control, wakefulness)

• Midbrain (motivation, learning, reinforcing pleasurable behaviour)

• Forebrain (abstract thought, planning, associations of thoughts and memories)

Drugs and the brain

Drugs and the brain

The Brain

Drugs and the brain

The Brain – major regions

Drugs and the brain

The Brain – areas of the cerebral cortex

Drugs and the brain

The Brain – the reward system

Drugs and the brain

Neurons, Brain Chemistry and Neurotransmission

Drugs and the brain

Neurons, Brain Chemistry and Neurotransmission

Drugs and the brain

Neurons, Brain Chemistry and Neurotransmission

Drugs and the brain

Neurotransmitters• Communication in the brain through

chemical messengers (neurotransmitters)

• Neurotransmitters have specific structures and functions.

• Which chemical is released depends upon the type of neuron.

• Each specific neurotransmitter binds to a specific receptor (lock/key)

Drugs and the brain

Neurons, Brain Chemistry and Neurotransmission

Drugs and the brain

Neurons, Brain Chemistry and Neurotransmission

Drugs and the brain

Psychoactive substances• Psychoactive substances mimic the

effects of neurotransmitters or interfere or even block normal function

• PA substances that bind and enhance the function of receptors: agonists

• PA substances that block normal functioning: antagonists

Drugs and the brain

Drugs change the way Neurons communicate

Source: Science & Practice Perpectives (NIDA, april 2007)

Drugs and the brain

Drugs and the brain

Dependence• Dependence is the result of a

complex interaction of the physiological effects of substances on brain areas associated with motivation and emotion, combined with ‘learning’ about the relationship between substances and substance-related cues.

Drugs and the brain

Mesolimbic dopamine pathway• Many psychoactive substances

activate the mesolimbic dopamine pathway (located in the midbrain)

• Most strongly implicated in the dependence-producing potential of psychoactive substances

Drugs and the brain

Mesolimbic dopamine pathway (MDP)• MDP closely involved in motivational

processes• Motivation: allotment of attentional

and behavioral resources to stimuli in relation to their predicted consequences

• Incentives: stimuli that elicit a response on the basis of their predicted consequences

Drugs and the brain

Two important areas• Ventral Tegmental Area (VTA) – rich in

neurons containing dopamine (emotions, thoughts, memories, planning, executing behavior)

• Nucleus Accumbens (NAc) – related to motivation and learning, signalling the motivational value of stimuli

Drugs and the brain

Source: NIDA website http://www.drugabuse.gov/pubs/teaching

Mesolimbic dopamine pathway

Drugs and the brain

Major brain regions with roles in addiction

Source: Science & Practice Perpectives (NIDA, april 2007)

Drugs and the brain

Brain regions and function• The prefrontal cortex is the focal area for

cognition and planning. • The ventral tegmental area (VTA) and

nucleus accumbens (NAc) are key components of the brain’s reward system.

• The VTA, NAc, amygdala, and hippocampus are major components of the limbic system, which coordinates drives, emotions, and memories.

Drugs and the brain

Brain Imaging Techniques• Structural Magnetic Resonance

Imaging (MRI)• Functional MRI• Magnetic Resonance Spectroscopy

(MRS)• Positron Emission Tomography (PET)• Single Photon Emission Computed

Tomography (SPECT)

Drugs and the brain

Brain Imaging Techniques knowledge:

• Brain anatomy and tissue composition• Biochemical, physiological and

functional processes• Neurotransmitter activity• Energy utilization and blood flow• Drug distribution and kinetics

Drugs and the brain

Brain Imaging Techniques used in drug abuse research

Source: Science & Practice Perpectives (NIDA, april 2007)

Drugs and the brain

The Brain on cocaine

Drugs and the brain

The Brain on cocaine

Drugs and the brain

The Brain on opiates

Drugs and the brain

The Brain on THC

Drugs and the brain

Drugs of abuse all activate the reward system via increasing dopamine neurotransmission