Transcript Brain & Behavior & Drugs

Brain and Behavior and
nd
Drugs: 2 pt
Chapter 3
1
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.
Association Areas
More intelligent animals have increased
“uncommitted” or association areas of the
cortex.
Language
Aphasia 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 Brain
A procedure in which the two hemispheres of the
brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Martin M. Rother
Courtesy of Terence Williams, University of Iowa
Corpus Callosum
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.
BBC
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. Stimulants
3. Hallucinogens
Depressants
Depressants are drugs that reduce neural activity
and slow body functions. They include:
1. Alcohol
2. Barbiturates
3. Opiates
Depressants
1. Alcohol affects motor skills, judgment, and
memory…and increases aggressiveness while
reducing self awareness.
Daniel Hommer, NIAAA, NIH, HHS
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
http://opioids.com/timeline
3. Opiates: Opium and its
derivatives (morphine
and heroin) depress
neural activity,
temporarily lessening
pain and anxiety. They
are highly addictive.
Stimulants
Stimulants are drugs that excite neural activity and
speed up body functions. Examples of stimulants
are:
1.
2.
3.
4.
5.
6.
Caffeine
Nicotine
Cocaine
Ecstasy
Amphetamines
Methamphetamines
Caffeine & Nicotine
Caffeine and nicotine increase heart and
breathing rates and other autonomic functions to
provide energy.
Cocaine
Induces immediate euphoria followed by a crash. Crack, a
form of cocaine, can be smoked. Other forms of cocaine can
be sniffed or injected.
http://www.ohsinc.com
Ecstasy
A stimulant and mild
hallucinogen.
Produces a euphoric high
and can damage serotoninproducing 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 (mindmanifesting) 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 Therapies
2. Brain Stimulation
3. 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