1

Brain and Behavior and Drugs: 2nd pt

Chapter 3

Association Areas

• Although small, well-defined regions within these lobes control muscle movement and receive information from the body senses, most of the cortex—its association areas—are free to process other information.

Association Areas

• Association areas are NOT involved in primary motor or sensory functions.

• They integrate and act on information processed by the sensory areas.– Are involved in higher mental functions, such as

learning, remembering, thinking, and speaking.

• Association areas are found in all four lobes.– Complex human abilities, such as memory and

language, result from the intricate coordination of many brain areas.

More intelligent animals have increased “uncommitted” or association areas of the

cortex.

Association Areas

LanguageAphasia is an impairment of language, usually caused by left hemisphere damage either to

Broca’s area (impaired speaking) or to Wernicke’s area (impaired understanding).

Specialization & Integration

Brain activity when hearing, seeing, and speaking words

The Brain’s Plasticity

• The brain is sculpted by our genes but also by our experiences.– Plasticity refers to the brain’s ability to modify itself

after some types of injury or illness.

• Research indicates that some neural tissue can reorganize in response to damage. When one brain area is damaged, others may in time take over some of its function.– If you lose a finger, the sensory cortex that received

its input will begin to receive input from the adjacent fingers, which become more sensitive.

The Brain’s Plasticity• Our brains are most plastic when we are young

children.• Constraint-induced therapy rewires the brain by

restraining a fully functioning limb and forcing use of the “bad hand” or the uncooperative leg.– Eventually, the therapy reprograms the brain,

improving the dexterity of a brain-damaged child or even an adult stroke victim.

• New evidence reveals that adult humans can also generate new brain cells.– Monkey brains illustrate neurogenesis by forming

thousands of new neurons each day.

Our Divided Brain

Our brain is divided into two hemispheres. The left hemisphere processes reading,

writing, speaking, mathematics, and comprehension skills. In the 1960s, it was

termed as the dominant brain.

Splitting the BrainA procedure in which the two hemispheres of the brain are isolated by cutting the connecting fibers

(mainly those of the corpus callosum) between them.

Corpus Callosum

Ma

rtin M

. Ro

the

r

Courtesy of T

erence William

s, University of Iow

a

Split Brain Patients

With the corpus callosum severed, objects (apple) presented in the right visual field can be named.

Objects (pencil) in the left visual field cannot.

Divided Consciousness

Try This!

Try drawing one shape with your left hand and one with your right hand, simultaneously.

BB

C

Drugs: Affecting our own Consciousness

• Dependence and Addiction

• Psychoactive Drugs

• Influences on Drug Use

Drugs and Consciousness

Psychoactive Drug: A chemical substance that alters perceptions and mood (affects

consciousness).

Dependence & Addiction

Continued use of a psychoactive drug

produces tolerance. With repeated

exposure to a drug, the drug’s effect lessens. Thus it takes greater

quantities to get the desired effect.

Withdrawal & Dependence

1. Withdrawal: Upon stopping use of a drug (after addiction), users may experience the undesirable effects of withdrawal.

2. Dependence: Absence of a drug may lead to a feeling of physical pain, intense cravings (physical dependence), and negative emotions (psychological dependence).

Psychoactive Drugs

Psychoactive drugs are divided into three groups.

1. Depressants 2. Stimulants3. Hallucinogen

s

Depressants

Depressants are drugs that reduce neural activity and slow body functions. They include:

1. Alcohol 2. Barbiturat

es3. Opiates

Depressants

1. Alcohol affects motor skills, judgment, and memory…and increases aggressiveness while reducing self awareness.

Daniel H

omm

er, NIA

AA

, NIH

, HH

S

Moderate Alzheimer’s

Depressants

2. Barbiturates: Drugs that depress the activity of the central nervous system, reducing anxiety but impairing memory and judgment. Nembutal, Seconal, and Amytal are some examples.

Depressants

3. Opiates: Opium and its derivatives (morphine and heroin) depress neural activity, temporarily lessening pain and anxiety. They are highly addictive.

http://opioids.com/tim

eline

StimulantsStimulants are drugs that excite neural activity and speed up body functions. Examples of stimulants are:

1. Caffeine 2. Nicotine3. Cocaine4. Ecstasy5. Amphetamines6. Methamphetamines

Caffeine & Nicotine

Caffeine and nicotine increase heart and breathing rates and other autonomic

functions to provide energy.

CocaineInduces immediate euphoria followed by a crash. Crack, a form of cocaine, can be smoked. Other

forms of cocaine can be sniffed or injected.

http://ww

w.ohsinc.com

Ecstasy

A stimulant and mild hallucinogen.

Produces a euphoric high and can damage serotonin-producing

neurons, which results in a permanent deflation of mood and impairment

of memory.

Methamphetamines

• Highly Addictive– Triggers strong release of dopamine, norepinephrine,

and serotonin

Hallucinogens

Hallucinogens are psychedelic (mind-manifesting) drugs

that distort perceptions and evoke sensory images in the

absence of sensory input.

Hallucinogens

1. LSD: Powerful hallucinogenic drug Serotonin agonist.

2. THC: Cannabinoid receptors are found in parts of the brain that influence pleasure, memory, concentrating, time perception and coordinated movement.

Marijuana Use

The use of marijuana in teenagers is directly related to the “perceived risk” involved with the drug.

Influences on Drug Use

The use of drugs is based on biological, psychological, and social-cultural influences.

Drugs & Other Therapies

• Drug Therapies• Brain Stimulation• Psychosurgery• Therapeutic Life-Style Changes

The Biomedical Therapies

These include physical, medicinal, and other forms of biological therapies.

1. Drug Therapies2. Brain Stimulation3. Psychosurgery

Drug Therapies

Psychopharmacology is the study of drug effects on mind and behavior.

With the advent of drugs, hospitalization in mental institutions has rapidly declined.

Drug Therapies

Many patients are left homeless on the streets due to their inability to cope independently in

society.

Margaret Holloway aka The Shakespeare Lady

How Neurotransmitters Influence Us

Serotonin pathways are involved with mood regulation.

Dopamine Pathways

Dopamine pathways are involved with diseases such as

schizophrenia and Parkinson’s disease.

Antipsychotic Drugs

Classical antipsychotics [chlorpromazine (Thorazine)]: Remove a number of positive symptoms associated with schizophrenia such as agitation,

delusions, and hallucinations.

Atypical antipsychotics [clozapine (Clozaril)]: Remove negative symptoms associated with

schizophrenia such as apathy, jumbled thoughts, concentration difficulties, and

difficulties in interacting with others.

Atypical Antipsychotic

Clozapine (Clozaril) blocks receptors for dopamine and serotonin to remove the negative symptoms of schizophrenia.

Antianxiety Drugs

Antianxiety drugs (Xanax and Ativan) depress the central nervous system and reduce anxiety and tension by elevating the levels of the Gamma-aminobutyric acid (GABA) neurotransmitter.

Antidepressant Drugs

Antidepressant drugs like Prozac, Zoloft, and Paxil are Selective Serotonin Reuptake

Inhibitors (SSRIs) that improve the mood by elevating levels of serotonin by inhibiting

reuptake.

Mood-Stabilizing Medications

Lithium Carbonate, a common salt, has been used to stabilize manic episodes in bipolar

disorders. It moderates the levels of norepinephrine and glutamate neurotransmitters.

Brain Stimulation

Electroconvulsive Therapy (ECT)

ECT is used for severely depressed patients who do not respond to drugs.

The patient is anesthetized and given a

muscle relaxant. Patients usually get a 100 volt shock that

relieves them of depression.

Alternatives to ECT

Repetitive Transcranial

Magnetic Stimulation (rTMS)

In rTMS, a pulsating magnetic coil is

placed over prefrontal regions of the brain to treat depression with minimal side effects.

Psychosurgery

Psychosurgery was very popular even in

Neolithic times. Although used

sparingly today, about

200 such operations do take place in the

US alone. Lobotomy

Psychosurgery

Used as a last resort in alleviating psychological disturbances. Psychosurgery

is irreversible. Removal of brain tissue changes the mind.

Lesions are made by radiation, thermo-coagulation, freezing or cutting.

Psychological Disorders are Biopsychosocial in Nature

Neurotransmitters