The Brain and Nervous System -...

Psychology : Concepts and Connections, Ninth Edition, Spencer A. Rathus

Chapter 2

The Brain and Nervous System

How Biology Impacts Our BehaviorChapter 2


Chapter 2

True or False?

1. A small amount of brain tissue from a person

cannot be distinguished from that of a monkey.

2. Both animals and humans seem to have reward

centers located in the brain.

3. Some people can write but are unable to read.

4. Adult humans cannot generate new brain cells.

5. Identical twins are both left-handed or right-

handed.


Chapter 2The Nervous System

Neurons: the nerve cells of the body

– Cell Body:

• contains the nucleus which generates

energy

– Dendrites:

• receive incoming messages from

adjourning cells (roots).

– Axon:

• carry messages away from the cell

body (trunk).


Chapter 2

../../Video_Clips/NEURPRTS.mov

NEURPRTS.mov


Chapter 2

Figure 2.5 The anatomy of a neuron. Message enter neurons through dendrites, are transmitted along the trunklike

axon, and are then sent from the axon terminal buttons to muscles, glands and other neurons. Axon terminal buttons

contain sacs of chemicals called neurotransmitters. Neurotransmitters are released into the synaptic cleft, where

many of them bind to receptor sites on the dendrite of the receiving neuron. Dozens of neurotransmitters have been

identified.


Chapter 2The Nervous System

Parts of a neuron continued.

– Terminals (terminal buttons):

• bulb shaped structure at the end of the axon.

– Myelin:

• fatty substance around axons that facilitate conduction – Guianne Barre.

– Glial cells:

• remove dead neurons and waste products from the nervous system.


Chapter 2The Neural Impulse

• A message traveling along the neuron; between 2

and 225 miles an hour.

• An Electrochemical Voyage.

– Neuron resting potential:

• -70 millivolts (negative charge).

– Depolarized:

• action of the cell while it becomes positively

charged.

– Action potential:

• positively charged neuron returning to the

resting state of being negatively charged.

The “message” is sent.


Chapter 2

Action Potential.mov

Action Potential.mov


Chapter 2

Figure 2.6 When a section of a neuron is stimulated by other neurons, the cell membrane becomes permeable to

sodium ions so that an action potential of about 40 millivolts is induced. This action potential is transmitted along the

axon. The neuron fires according to the all-or-none principle.


Chapter 2Firing

neurons attempt to transmit messages to other neurons, muscles or glands.

– Threshold:

• Each neuron has a threshold; the cell will not fire until the threshold is reached.

– All or None Principle:

• When the threshold is reached the neuron fires an impulse of the same strength.

– Refractory Period:

• period of recovery during which positive sodium is not allowed to pass through the neural membrane.

– Synapse:

• Junction (fluid filled gap between neurons).


Chapter 2Neurotransmitters: The Chemical Keys to Communication

• Synaptic Vesicles:

– sacs in the axon terminals which contain neurotransmitters.

• Neurotransmitters:

– the chemical keys to communication which influence the receiving neuron

– Receptor Site:

• specifically tailored site on the receiving neuron where the chemical key (neurotransmitter) fits.

– Reuptake:

• reabsorption of neurotransmitters by the sending neuron.

– Excitatory:

• neurotransmitter influence on the receiving cell causing it to fire.

– Inhibitory:

• neurotransmitter influence on the receiving cell preventing it from firing.


Chapter 2

../../Video_Clips/SYNAPSE.mov

SYNAPSE.mov


Chapter 2

Neurotransmitters –

See chart on page 53 of the text


Chapter 2Types of Neurotransmitters

Acetylcholine (ACh):

– controls muscle contractions; can be both excitatory and inhibitory.

– Curare and Botulism both leading to paralysis.

– Decreases in ACh is associated with Alzheimer's related memory problems.



Dopamine:

– affects voluntary movements, learning, memory and arousal.

– Deficiencies are linked to Parkinson‟s Disease.

– People with schizophrenia may have more receptor sites for dopamine leading to confusion and false perceptions.


Chapter 2

../../Video_Clips/Interfere_Syn_Trans.mov

Interfere_Syn_Trans.mov



Norepinephrine:

– produced largely in the brain stem; acts as a neurotransmitter and as a hormone;

– involved in general arousal, learning and memory, and eating; linked to mood disorders.

– Cocaine creates an excess of norepinephrine leading to persistent arousal.



Serotonin:

– involved in emotional arousal and sleep.

– Deficiencies have been linked to eating

disorders, alcoholism, depression,

aggression, and insomnia.



Gamma-aminobutyric acid (GABA):

– inhibitory neurotransmitter that may

help calm anxiety reactions.

– Tranquilizers and alcohol may quell

anxiety by binding with GABA

receptors.



Endorphins:

– inhibitory neurotransmitter;

endogenous morphine.

– Natural painkiller.

– Experienced by runners as the

runner‟s high.


Chapter 2The Parts of the Nervous System

Nerve:

– a bundle of axons.

• Central Nervous System:

– brain and spinal cord.

• Peripheral Nervous System:

– afferent and efferent neurons which

transmit messages from the brain or

spinal cord to muscles and glands.


Chapter 2

Figure 2.8 The Divisions of the Nervous System. The nervous system contains two main divisions: the central

nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal

cord. The peripheral nervous system contains the somatic and autonomic systems. In turn, the autonomic nervous

system has sympathetic and parasympathetic divisions.


Chapter 2The Peripheral Nervous System

Somatic Nervous System:

– afferent and efferent neurons that transmit sights, sounds, smells, temperature, body positions, etc.

– Purposeful body movements.


Chapter 2The Peripheral Nervous System

Autonomic Nervous System:

– “Automatic” regulates the glands and internal organ muscles; heartbeat, respiration, digestion, dilation of the pupils, etc.

• Sympathetic Division:

– active during processes that involve spending body energy; fight or flight.

• Parasympathetic Division:

– active during processes that replenish reserves of energy.


Chapter 2

Figure 2.9 The Branches of the Autonomic Nervous System. The parasympathetic branch of the ANS generally

acts to replenish stores of energy in the body. The sympathetic branch is the most active during activities that expend

energy. The two branches of the ANS frequently have antagonistic effects on the organs they service.


Chapter 2The Central Nervous System

Spinal Cord: column of nerves transmits messages

from sensory receptors to the brain and from the

brain to muscles and glands throughout the body

– Spinal Reflexes: unlearned response to a

stimulus that may involve only two neurons:

afferent and efferent.

– Interneuron: a third neuron that transmits the

neural impulse from the sensory neuron through

the spinal cord to the motor neuron.

– Gray Matter: non-myelinated neurons; found in

brain and spinal cord.

– White Matter: myelinated neurons; found in brain

and spinal cord.


Chapter 2The Endocrine System: Chemicals in the Bloodstream

Glands: secrete hormones.

– Two types:

•With ducts (saliva, sweat, tears).

•Without ducts (released into the blood

stream).

• Pituitary Gland:

– implicated in growth.

– sometimes referred to as the Master

Gland as it influences other glands in

the endocrine system.


Chapter 2Types of Hormones

• Growth Hormone:

– regulates growth of muscles, bones and glands.

• Prolactin:

– regulates maternal behavior in lower animals such as rats, also produces milk in women.

• Antidiuretic Hormone (ADH):

– inhibits production of urine when fluid levels in the body are low.

• Oxytocin:

– stimulates labor in pregnant women.

• Melatonin:

– secreted by the Pineal gland and helps regulate the sleep-wake cycle.



• Thyroxin:

– secreted by the thyroid and affects the body‟s metabolism.

•Hypothyroidism is too little thyroxin and results in being overweight.

•Hyperthyroidism is too much thyroxin and is characterized by excitability, insomnia, and weight loss.

•Cretinism is a conditioned caused by a deficiency in thyroxin in children which leads to stunted growth and mental retardation.


Chapter 2

• Adrenal glands:

– release hormones to increase resistance to stress.

– Promote muscle development and the release of sugar in the liver making more energy available.

– Epinephrine: is also known as adrenaline; produced by the adrenal glands.



• Testosterone: produced by the testes and in small amounts by the ovaries.

– Considered to be the male sex hormone as it aids in the development of male sex organs.

– During puberty the release of testosterone promotes the development of primary and secondary sex characteristics.

– Primary sex characteristics:

• those characteristics involved in reproduction: increased penis size, sperm producing ability of the testes.

– Secondary sex characteristics:

• Not directly related to reproduction: presence of a beard, deeper voice.


Chapter 2

• Estrogen and Progesterone: produced by the ovaries and in small amounts by the testes.

– Fosters female reproductive capacity and secondary sex characteristics.

– The levels of estrogen and progesterone vary and regulate the woman‟s menstrual cycle.


Chapter 2Steroids, Behavior and Mental Processes

• Anabolic (synthetic) steroids are used

with growth hormone to enhance

–Athletic prowess

–Self-confidence

–Aggressiveness

–Memory functioning

• Linked liver damage and other health

problems


Chapter 2

THE BRAIN


Chapter 2The Brain: The Star of the Nervous System

Gender Differences

– Size

•Men 15% larger (related to body

size difference)

– How well connected

•Women metabolize more glucose

and use more of their brains


Chapter 2

How do Psychologists study

the brain?


Chapter 2Seeing the Brain Through the Eyes of the Psychologist

• Accidents.

– provide unplanned, uncontrolled opportunities of

studying the brain

• Experimenting with the Brain.

– Lesioning: damaging part of the brain.

• The Electroencephalograph (EEG).

– EEG detects minute amounts of electrical

activity in the brain.


Chapter 2Seeing the Brain Through the Eyes of the Psychologist

Brain Imaging Techniques.

– CAT (computerized axial tomograph)

– PET (positron emission tomography):

computer

– MRII (magnetic reasoning imaging):


Chapter 2

CAT (computerized axial tomograph)

• A scan which passes a narrow X-ray

beam through the head and measures

brain structures.

• Generates a three dimensional image

of the brain.

• Reveals deformities in shape and

structure that are connected with blood

clots, tumors, and other health

problems.


Chapter 2

MRI (magnetic reasoning imaging)

• Person lies in a powerful magnetic field

and is exposed to radio waves that cause

parts of the brain to emit signals.

• Relies on subtle shifts in blood flow.

• MRI has shown people with

schizophrenia have smaller prefrontal

regions but larger ventricles.


Chapter 2

../../Video_Clips/Brain_Mapping.mov

Brain_Mapping.mov


Chapter 2

PET (positron emission tomography)

• computer generated image of the activity of parts of the

brain by tracing the amount of glucose used.

• A harmless amount of radioactive compound (tracer) is

mixed with glucose and injected into the blood stream.

• Used to see which parts of the brain are most active when

we are engaged in various activities

– Examples include:

• listening to music,

• working out, and

• math problems


Chapter 2

BRAIN STRUCTURES AND FUNCTIONS


Chapter 2

Brain structure overview video

Pinky and the Brain.mpeg


Chapter 2Voyage Through the Brain

• Hindbrain: where the spinal cord meets the brain.

Contains three structures.

– Medulla:

• regulates vital functions such as heart rate,

blood pressure, and respiration.

– Pons:

• transmits information about body movements

and is involved in functions related to

attention, sleep/alertness and respiration.

– Cerebellum:

• involved in maintaining balance and

controlling motor behavior.


Chapter 2

Figure 2.13 The Parts of the Human Brain. This view of the brain, split top to bottom, shows some of the most

important structures. Note how close the hypothalamus is to the pituitary gland. The proximity allows the

hypothalamus to readily influence the pituitary gland. The “valleys” in the cerebrum are called fissures.


Chapter 2Voyage Through the Brain

• Reticular Activating System (RAS):

– vital in the functions of attention,

sleep and arousal.


Chapter 2

Forebrain• forward most part of the brain containing

thalamus, hypothalamus, limbic system and the

cerebrum.

• Thalamus:

– relay station for sensory stimulation.

• Hypothalamus:

– vital for body temperature regulation,

concentration of fluids, storage of nutrients,

aspects of motivation and emotion.

– Also involved in hunger, thirst and sexual

behavior.


Chapter 2

../../Video_Clips/stimul_lhypothlms.mov

stimul_lhypothlms.mov


Chapter 2

• Limbic System:

– Includes the amygdala, hippocampus, and parts of the hypothalamus.

– Involved in memory, emotion and in the drives of hunger, sex and aggression.

– Amygdala:

• connected with aggression, fear response, and vigilance.

• Cerebrum:

– responsible for thinking and language.

Forebrain


Chapter 2

Figure 2.14 The Limbic System. The limbic system is made up of structures that include the amygdala, the

hippocampus, and parts of the hypothalamus. It is evolved fully only in mammals and forms a fringe along the inner

edge of the cerebrum. The limbic system is involved in memory and emotion, and in the drives of hunger, sex, and

aggression


Chapter 2

The Cerebral Cortex

• Outer layer of the cerebrum about 1/8 of an inch thick.

• Involved in most bodily activities, sensations, and responses.

– Frontal Lobe:

• In front of the central fissure.

• Contains the motor cortex, which causes our body to move.

– Parietal Lobe:

• Behind central fissure.

• Contains the somatosensory cortex which receives messages from skin senses all over the body.


Chapter 2

– Temporal Lobe:

• Lies below the lateral fissure.

• Contains the auditory area (hearing).

– Occipital Lobe:

• lies behind the temporal lobe.

• Is involved with vision.

The Cerebral Cortex


Chapter 2

Figure 2.15 The Geography of the Cerebral Cortex. The cortex is divided into 4 lobes: frontal, parietal, temporal,

and occipital. The visual area of the cortex is located in the occipital lobe. The hearing or auditory cortex lies in the

temporal lobe. The sensory and motor areas face each other across the central fissure.

Sensory and

Motor Cortexes


Chapter 2Language Functions

Aphasia: disruption in the ability to understand or

produce language.

– Wernicke‟s Area:

• in the temporal lobe responds mainly to

auditory information.

– Wernicke‟s aphasia:

– impaired ability to comprehend speech

and to think of the proper words to

express.


Chapter 2

– Broca‟s area:

• processes information and sends it

to the motor cortex.

– Broca‟s aphasia:

• Damage to this area results; people

can understand language but will

speak slowly in simple sentences.


Chapter 2

Figure 2.16 Broca’s and Wernicke’s Areas of the Cerebral Cortex. The areas that are most involved in speech

are Broca‟s area and Wernicke‟s Areas of the Cerebral Cortex. Damage to either area can produce an aphasia--a

disruptions o the ability to understand or produce language.


Chapter 2

Phineas Gage, A Classic Example

Phineas Gage.mpeg


Chapter 2

Phineas Gage, A Classic Example

• Impact of the case

– Demonstrates divisions and

specialization of brain

– Beginnings of Neurobiology


Chapter 2

Corpus Callosum

• a bundle of some 200 million nerve

fibers connecting the two hemispheres.


Chapter 2Left Brain, Right Brain

Left Brain, Right Brain.

– Left brain:

• primarily logical and intellectual.

– Right brain:

• primarily intuitive, creative, and

emotional.

• At best this is exaggerated.

• The hemispheres do not act independently as they

are connected by the corpus callosum.


Chapter 2

•Allows two hemispheres of the brain to

communicate

•May be cut in patients with seizures

•How would this affect the patient?

../../Video_Clips/corpus_callosum.mov

corpus_callosum.mov


Chapter 2

Split Brain Experiments

• Some people with epilepsy have split brain

operations in which much of their corpus

callosum is severed.

• Each hemisphere has a mind of it‟s own.

– One patient described a situation he

encountered, as one hemisphere liking

reading and other not.

– If he shifted the book from his right hand to

his left, his left hand would put the book

down.


Chapter 2

Split-Brain Patient Video

Split Brain experiments.mpeg




Chapter 2

Figure 2.18 A Divided-Brain Experiment. In the drawing on the left, we see that visual sensations in the left visual

field are projected in the occipital cortex of the right hemispheres. Visual sensations from the right visual field are

projected in the occipital cortex in the left hemisphere. In the divided-brain experiment diagrammed on the right, a

person with a severed corpus callosum handles a key with his left hand and perceives the written word key in his left

visual field. The word „key” is projected in the right hemisphere. Speech, however is usually a function of the left

hemisphere. The written word “ring” perceived by the right visual field is projected in the left hemisphere. So when

asked what he is handling, the divided-brain subject reports “ring,” not “key.”


Chapter 2Handedness

Is It Gauche or Sinister to Be Left Handed?

– Lefties: 8-10% of people are left handed;

more common in males.

• Has been connected with language

problems, dyslexia, stuttering, migraine

headaches, allergies, schizophrenia.

• On the other side being left handed is

associated with artists, musicians, and

mathematicians.

– Handedness runs in families.

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