Neuroscience of Mental Health

NEUROSCIENCE OFMENTAL HEALTH

Source: Mental Health: A Report of the Surgeon General

www.surgeongeneral.gov/library/mentalhealth/chapter2/sec1.html#neuroscience

Mind and Body

The mind and the body are inseparable.

Mental health and physical health are intertwined.

Mental functions are carried out by the brain.Likewise, mental disorders are reflected in physicalchanges in the brain.

Instead of dividing physical from mental health, themore appropriate distinction is between “mental”and “somatic” health.

Somatic is a medical term for the body.

Mental Health

The successfulperformance of mentalfunctions in terms ofthought, mood, andbehavior.

Mental disorders arethose health conditionsin which alterations inmental functions areparamount.

Somatic Health

The successfulperformance ofphysical functions.

Somatic conditions arethose in whichalterations innonmental functionspredominate.

Mental Health

The brain carries out allmental functions

Example: Stroke

When a stroke producesalterations of thought,mood, or behavior, it isconsidered a mentalcondition (e.g.,dementia).

Somatic Health

The brain carries outsome somatic functions,such as movement, touch,and balance.

Example: Stroke

When a stroke causes alesion in the brain thatproduces disturbances inmovement, it is considereda somatic condition (e.g.,paralysis).

The brain and mind are two sides of the same coin.

Mind is not possible without the remarkable physicalcomplexity that is built into the brain.

In addition, the physical complexity of the brain isuseless without the sculpting that environment,experience, and thought itself provides.

Thus, the brain is now known to be physicallyshaped by contributions from our genes and ourexperience, working together.

This strengthens the view that mental disorders areboth caused and can be treated by biological andexperiential processes, working together.

This understanding has emerged from the progressin modern neuroscience that has begun to integrateknowledge from biological and behavioral sciences.

Complexity of the Brain 1: Structural

The human brain is an amazingly complex structure.

The brain contains approximately 100 billion nervecells (neurons) and many more supporting cells(glia).

Most organs in the body are composed of only ahandfull of cell types.

The brain, in contrast, has thousands of differentkinds of neurons, each distinct in terms of itschemistry, shape, and connections.

The workings of the brain depend on the ability ofnerve cells to communicate with each other.

The output of neurons is carried along the axon.

The input to neurons is received by dendrites.

Communication occurs in small, specialized structurescalled synapses.

The synapse has two parts.

1.A specialized presynaptic terminal on the end of aportion (axon) of the sending neurons that containspackets of signaling chemicals (neurotransmitters).

2.A postsynaptic potential on the dendrites of thereceiving neuron that has receptors forneurotransmitter molecules.

http://www.surgeongeneral.gov/library/mentalhealth/chapter2/images/fig2_2.jpg

CELL BODY

NUCLEUS

AXON

AXONTERMINAL

SYNAPSE

AXON

DENDRITE

The usual form of communication involves electricalsignals that travel within neurons, giving rise tochemical signals that cross synapses, which lead tonew electrical signals.

Ultimately, the pattern of synaptic connections givesrise to what are called circuits in the brain.

One of the most awe-inspiring mysteries of brainscience is how neuronal activity within circuits givesrise to behavior and, even, consciousness.

The specific connectivity of circuits is, to somedegree, stereotyped, or set in expected patternswithin the brain, leading to the notion that certainplaces in the brain are specialized for certainfunctions.

Parietal Lobe

Frontal Lobe

Temporal Lobe

OccipitalLobe

Cerebral cortex

Occipital lobe – involved in the initial stages of visualprocessing.

Parietal lobe – involved in the processing of tactileinformation.

Frontal lobe – involved in motor behavior

Prefrontal lobe – involved with some of the highestintegrated function of the human being, including the abilityto plan and to integrate cognitive and emotional streams ofinformation.

Temporal lobe - important for the processing of speechand vision. Contains the hippocampus and plays a keyrole in the formation of long-term memory.

Complexity of the Brain 2: Neurochemical

In addition to the structural complexity is hechemical complexity of the brain.

Electrical signals within neurons are changed atsynapses into chemical signals which then causeelectrical signals on the other side of the synapse.

These chemical signals are molecules calledneurotransmitters.

There are two major kinds of molecules that servethe function of neurotransmitters:

1.Small molecules, for example--

Dopamine

Serotonin

Norepinephrine

2.Large molecules, for example--

protein chains called peptides

Some of these neurotransmitters are responsible forbrain states such as degree of arousal, ability topay attention, and for adding emotionalsignificance to cold, hard facts.

This typs of neurotransmitter and their receptors arecritical targets of medications used to treat mentaldisorders – for example, the antidepressant andantipsychotic drugs – and also are the targets ofdrugs of abuse.

Complexity of the Brain 3: Plasticity

The most amazing thing about the brain is that it isnot static. The brain is always changing.

Every time a person learns something new, whetherit is conscious or unconscious, that experience altersthe structure of the brain.

Experience that is important enough to cause memorycreates new synaptic connections, prunes away oldones, and strengthens or weakens existing ones.

Similarly, experiences as diverse as stress, substanceabuse, or disease can kill neurons, and current datasuggest that new neurons continue to develop even inadult brains, where they help to incorporate newmemories.

The end result is that information is now routed over analtered circuit. Many of these changes are long-lived,even permanent. It is in this way that a person can lookback 10 or 20 or 50 years and remember family, ahome or school room, or friends.

Imaging of the Brain

Very important to the study of mental function andmental illness is the new ability to image the activityof the living human brain.

PET – positron emission tomography

fMRI – functional magnetic resonance imaging

Summary

Scientists are truly beginning to learn about the structureand function of the brain. Its awe-inspiring complexity isconsistent with the fact that it supports all behavior andmental life.

Brains are built not only by genes. Genes are not bythemselves the whole story. Brains are built and changedthrough life through the interaction of genes withenvironment, including experience.

It is this fundamental realization that is beginning to permitan understanding of how treatment of mental disordersworks—whether in the form of a somatic intervention such asa medication, or a psychological “talk” therapy—byactually changing the brain.