C H A P T E R ©2012 Pearson Education, Inc. All Rights Reserved. 4 Invitation to Psychology, 5e...

C H A P T E R

©2012 Pearson Education, Inc. All Rights Reserved.

4Invitation to Psychology, 5e Carole Wade and Carol Tavris

Neurons, Hormones, and the Brain

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Study of the brainNeuropsychologistsStudy the brain and the rest of the nervous system in hopes of

gaining a better understanding of behavior.

Includes the study of the biological foundations of consciousness, perception, memory, emotion, stress, and mental disorders.

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BASIC ANATOMYNervous System

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The central nervous system

Brain and Spinal cord

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Spinal reflexesAutomatic behaviors that occur on their own,

without any help from the brain

Ex. pulling your hand away from a burning hot surface.

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The peripheral nervous systemHandles the central nervous system’s input and output Somatic nervous systemAutonomic nervous system•Sympathetic nervous system•Parasympathetic nervous system

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Organization of the nervous system

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NEURONS

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Neurons•The brain’s communication specialists, transmitting information to, from, and within the central nervous system

Glial cells•Provide the neurons with nutrients, insulate them, protect the brain from toxic agents, and remove cellular debris when neurons die. •communicate chemically with each other and with neurons.

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Structure of a neuron

DendritesReceive information from other neurons and transmit messages toward the cell body.

Cell bodyKeeps the neuron alive and determines whether it should fire.

AxonTransmits messages away from the cell body to other neurons, or to muscles or glands.

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Myelin sheath•A fatty material that may surround the axon of a neuron•Speeds up the conduction of neural impulses

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Types of neurons

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Neurons in the newsNeurogenesisThe production of new neurons from immature stem cells

Stem cellsImmature cells that renew themselves and have the potential to develop into mature cells

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Stem-cell research•Embryonic stem cells can differentiate into any kind of human cell.

•In recent years, scientists have successfully reprogrammed cells from adult organs (skin cells), to become stem cells. These are called “induced pluripotent stem (IPS)” cells.

•Patient-advocacy groups hope that transplanted stem cells will eventually help people recover from diseases of the brain (such as Parkinson’s) and from damage to the spinal cord and other parts of the body.

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Action potential

•A brief change in electrical voltage that occurs between the inside and outside of an axon when a neuron is stimulated

•Produces an electric impulse that travels down the axon into the axon terminal and stimulates the release of neurotransmitters

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Communication

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How neurons communicate

•Axon terminals release neurotransmitters from synaptic vesicles.

•Neurotransmitters enter synapse.

•Neurotransmitters bind to receptors that they fit.

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Neurotransmitter•Chemical released by a transmitting neuron at the synapse that alters the activity of a receiving neuron

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Major neurotransmitters1. Serotonin - sleep, appetite, sensory perception, temperature regulation,

pain suppression, and mood2. Dopamine - voluntary movement, learning, memory, emotion, pleasure or

reward, and, possibly, response to novelty3. Acetylcholine – muscular action, cognitive functioning, memory and

emotion – Alzheimer’s patients have a loss of brain cells that produce acetylcholine

4. Norepinephrine – increased heart rate, slowing of intestinal activity during stress, learning, memory, dreaming, waking, sleep and emotion

5. GABA (gamma aminobutyric acid) - major inhibitory neurotransmitter in the brain; abnormal levels linked to sleep and eating disorders

6. Glutamate - major excitatory neurotransmitter in the brain, and is released by about 90 percent of the brain’s neurons

7. Endorphins – reduce pain, promote pleasure

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The endocrine systemEndocrine glands release hormones into the bloodstream…

…Hormones are chemical substances that affect the functioning of other organs.

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HormonesMelatonin•Regulates daily biological rhythms and promotes sleep.

Oxytocin•Facilitates lactation and, with vasopressin, facilitates bonding at birth.

Adrenal hormones•Involved in emotions and stressEx. Cortisol, epinephrine, and norepinephrine

Sex hormones•Regulate development and functioning of reproductive organs, as well as secondary sexual characteristics in males and females.Ex. Androgens, estrogens, and progesterone

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Which is correct?Which type of nervous-system chemical enables neurons to excite or inhibit each other?

A.NeurotransmittersB.EndorphinsC.Hormones

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Which is correct?Which type of nervous-system chemical affects functioning of target organs and tissues?

A.NeurotransmittersB.EndorphinsC.Hormones

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Mapping The Brain

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Electroencephalogram (EEG)•A recording of neural activity detected by electrodes

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Transcranial magnetic stimulation (TMS)

Involves delivering an electrical current through a wire coil on a person’s head

Can be used to•Produce motor responses•Temporarily inactivate an area of the brain•Treat depression (however the effectiveness of TMS for this use is unclear)

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Positron emission tomography

Active areas have increased blood flow.

Different tasks show distinct activity patterns.

A method for analyzing biochemical activity in the brain, using injections of a glucose-like substance containing a radioactive element

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Magnetic resonance imaging (MRI)

Magnetic fields produce vibrations in atoms.

These signals are detected by special receivers.

A computer turns them into pictures of the brain.

Functional MRI (fMRI) accomplishes this at a much higher rate than MRI.

Method for studying body and brain tissue

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Anatomy of the Brain

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The brain stemPonsInvolved in sleeping, waking, and dreaming

MedullaResponsible for certain automatic functions such as breathing and heart rate

Reticular activating systemArouses cortex and screens incoming information

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The cerebellum•Regulates movement and balance

•Involved in remembering simple skills and acquired reflexes

•Plays a part in: 1.Analyzing sensory information2.Solving problems3.Understanding words

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The thalamusRelays sensory messages to the cerebral cortex

Includes all sensory messages except those of smell, which are “processed” by the olfactory bulb

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Hypothalamus and pituitary gland

Involved in drives vital to survivalHunger, thirst, emotion, sex, and reproduction

Controls the autonomic nervous system

Pituitary glandSmall endocrine gland which releases hormones and regulates other endocrine glands

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The amygdalaResponsible forArousal

Regulation of emotion

Initial emotional response to sensory information

Plays important role inForming and retrieving emotional memories

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The hippocampusResponsible forStorage of new information in memory

Comparing sensory information with what the brain expects about the world

Enabling us to form spatial memories for navigating the environment

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The cerebrum•Largest brain structure

•Two cerebral hemispheres connected by a bundle of nerve fibers called the corpus callosum

•In charge of our higher forms of thinking

•Surrounded by cerebral cortex, a collection of several thin layers of cells (gray matter)

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Lobes of the cerebral cortex

1. Occipital lobes (visual cortex)2. Parietal lobes (somatosensory

cortex)3. Temporal lobesMemory, perception, emotion, and auditory cortexLeft lobe: Wernicke’s area

4. Frontal lobesEmotion, planning, creative thinking, initiating, and motor

cortexLeft lobe: Broca’s area

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The Two HemispheresNearly all right-handed and the majority of left-handed individuals process language mainly in the left hemisphere.

Many researchers believe in left-hemisphere dominance.

Others insist right-hemisphere is important for spatial visual problem solving, comprehending non-verbal sounds, and some language abilities.

http://videos.howstuffworks.com/health/human-brain-videos-playlist.htm#video-27692

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Where is the Self?•Modern brain scientists explain the mind or soul in physical terms as a product of the cerebral cortex.•Frontal lobes may play a critical role.

•Many still question the relationship between subjective experience and physical processes of the brain.

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“His” and “her” brains?Women have relatively larger areas of the frontal lobe and limbic system, whereas men have larger parts of the amygdala and parietal cortex.

There do appear to be sex differences in lateralization of language.Males show left hemisphere activation only.Females show left and right hemisphere activation.

http://videos.howstuffworks.com/health/human-brain-videos-playlist.htm#video-29101

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What do differences mean for behavior?Supposed differences are stereotypes.

Brain difference does not necessarily explain behavior or performance.

Sex differences in the brain could be the result rather than the cause of behavioral differences.

C H A P T E R ©2012 Pearson Education, Inc. All Rights Reserved. 4 Invitation to Psychology, 5e...

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Transcript of C H A P T E R ©2012 Pearson Education, Inc. All Rights Reserved. 4 Invitation to Psychology, 5e...