Chapter3Lecture.ppt

Biological Psychology



_{In this chapter we will examine:}

 What are the components of the nervous

system?

 _{How does the brain create mental processes}

Module 3.1

Measuring Brain Activity



_{Methods for looking at and mapping the brain}

include:

 Electroencephalographs and

Magnetoencephalographs (EEGs and MEGs) record electrical and magnetic activity in the brain.

 These readouts do not allow the viewing of

Measuring Brain Activity



_{Methods for looking at and mapping the brain}

include:

 Positron emission tomography (PET)

provides a high-resolution picture of brain activity using radioactivity from chemicals injected into the bloodstream.

 The color of the image indicates the level of

activity: red areas are most active, followed by yellow, green, and blue for the least active

Measuring Brain Activity



_{Methods for looking at and mapping the brain}

include:

 Functional magnetic resonance imaging (fMRI)

uses magnetic detectors outside the head to measure the amounts of hemoglobin and

oxygen in different areas of the brain.

 Highly active areas of the brain appear to use

The Major Divisions of the Nervous

System



_{The central nervous system and the}

peripheral nervous system

 The central nervous system consists of the

brain and the spinal cord.

 _{The central nervous system communicates with}

the rest of the body via the peripheral nervous system.

Figure 3.4

Figure 3.4 The nervous system has two major divisions: the central nervous system and the peripheral nervous system. Each of these has major subdivisions, as shown.

The Major Divisions of the Nervous System

_{The CNS and the peripheral nervous system}

 There are two sets of subdivisions of the

The Peripheral Nervous System



_{The somatic nervous system and autonomic}

nervous system

 The autonomic nervous system controls the

involuntary actions of the heart, stomach, and other organs. (think automatic)

 _{The somatic nervous system controls voluntary}

Figure 3.5

Figure 3.5 The human brain begins development as three lumps. By birth the forebrain has grown much larger than either the midbrain or the hindbrain, although all three structures perform essential functions.

The Forebrain



_{General structure}

 The forebrain

 The forebrain has two separate hemispheres, left

and right.

 Each hemisphere controls sensation and motor

functioning on the opposite side of the body.

 The hemispheres of the brain communicate with

each other through a thick bundle of axons crossing between them, called the corpus callosum.

The Forebrain



_{Cerebral cortex}

 The cerebral cortex

 The outer covering of the forebrain is known as the

cerebral cortex.

 It is made up of gray matter, the cell bodies of the

cortical neurons.

 The interior of the forebrain is made up of white

matter or axons of cortical neurons. It is white because of the myelin that coats axons.

The Forebrain



_{Cerebral cortex}

 The four lobes of the cerebral cortex

 It’s customary to represent the areas of the cerebral

cortex as four lobes: occipital, parietal, temporal, and frontal.

 The occipital lobe is at the rear of the head, and

contains many specialized areas for interpreting visual sensory information.

 There are areas both inside and outside the

The Forebrain



_{Cerebral Cortex}

 The four lobes of the cerebral cortex

 The parietal lobe is directly in front of the occipital

lobe.

 It contains the primary somatosensory cortex, the

area of the brain that is specialized for body senses and awareness of the location of body parts.

The Forebrain



_{Cerebral Cortex}

 The four lobes of the cerebral cortex

 The temporal lobes are located on the sides of the

head, near the ears.

 They are the main processing areas for hearing and

complex aspects of vision.

 The left temporal lobe contains important areas for

The Forebrain



_{Other structures that lie under or near the}

temporal lobe include the hypothalamus,

amygdala and hippocampus.

 The hypothalamus helps to regulate emotional

and motivated behavior.

 The amygdala, an almond-shaped structure

that is crucial for emotional processing, is deep inside the temporal lobes.

 The hippocampus is a vital structure for

The Forebrain



_{Cerebral cortex}

 The four lobes of the cerebral cortex

 The frontal lobes are at the front of the brain.

 They contain the primary motor cortex, an area

that is important for control of fine movements.

 The foremost part of the frontal lobes, the

prefrontal cortex, is responsible for organization, planning of action, and aspects of memory.

Figure 3.8

Concept Check

Which lobe is damaged if…

A person is unable to feel or locate the left side

of her body?

Concept Check



_{Which lobe is damaged if…}



_{A person has difficulty with fine movements}

with the right hand?

Concept Check



_{Which lobe is damaged if…}



_{A person has loss of vision in the right visual}

field?

Concept Check



_{Which lobe is damaged if…}



_{A person has impaired emotional experience}

and some hearing loss?

Between the Spinal Cord and

the Forebrain



_{The hindbrain & midbrain}

 The medulla, pons, and midbrain contain the

reticular activating system (or reticular formation).

 This structure regulates levels of arousal in the

How the Cerebral Cortex

Communicates with the Body



_{The hindbrain}

 The cerebellum is important for coordination

and timing.

 _{It is also in charge of tasks that require shifting}

of attention and discrimination between stimuli.

How the Cerebral Cortex

Communicates with the Body



_{The hindbrain}

 The medulla oblongata and the pons are two

important structures in the hindbrain.

 _{They contain the axons that control breathing}

and heart rate.

 They are also in charge of relaying sensory

information from the head and sending motor messages back to it.

Figure 3.6

How the Cerebral Cortex

Communicates with the Body



_{The spinal cord}

 Both reflex and voluntary responses are conducted

through the spinal cord.

 A reflex is a rapid, automatic response to a

stimulus. The spinal cord is usually the origination point of these responses.

 A voluntary response originates in the brain and

travels through the spinal cord to the muscles needed to carry out the movements.

Figure 3.11

Figure 3.11 The spinal cord receives sensory information from all parts of the body except the head. Motor nerves in the spinal cord send messages to control the muscles and glands.

The Peripheral Nervous System



_{The autonomic nervous system}

 A division of the peripheral nervous system that is

closely associated with the spinal cord is the autonomic nervous system.

 The individual has very little control over the

responses in this division, hence the name autonomic.

 The autonomic nervous system has two

The Peripheral Nervous System



_{The autonomic nervous system}

 The divisions of the autonomic nervous system

 The sympathetic nervous system is the crisis

management center.

 It increases heart and respiration rate and prepares

the body for fight or flight.

 A chain of neurons lying just outside the spinal cord

The Peripheral Nervous System



_{The autonomic nervous system}

 The divisions of the ANS

 The parasympathetic nervous system runs

long-term survival-related functions, nutrition, and energy conservation.

 It decreases heart rate, increases digestive

activities, and promotes processes that take place during rest.

 It is controlled by neurons at the upper and lower

Figure 3.12

Figure 3.21 The sympathetic nervous system prepares the body for brief bouts of vigorous activity; the parasympathetic nervous system promotes digestion and other non-emergency functions. Although both systems are active at all times, the balance can shift from a predominance of one to a predominance of the other.

The Endocrine System



_{The endocrine system is under the control of}

the nervous system.

 The endocrine system is a system of glands

that release hormones into the bloodstream.

 _{Hormones are chemicals that affect mood,}

behavior, and even anatomy.

 Some neurotransmitters act as hormones when

released into the bloodstream. An example of one of these is epinephrine.

Figure 3.13

Figure 3.13 Glands in the endocrine system produce hormones and release them into the bloodstream. This shows only some of the endocrine glands and some of their most abundant hormones.

Experience and the Brain



_{Nerve cell generation}

 Neurons can be generated later in life (to a

limited extent).

 It was once thought that all neurons developed well

before birth.

 Researchers have discovered stem cells -

undifferentiated cells growing in some brain areas that are capable of developing into neurons in older organisms.

Experience and the Brain



_{Learning changes the brain}

 We now know, because we can “see” the brain

and its activity, that practicing behaviors (learning to play a musical instrument, for

example) can change the structure of the brain by altering the cortical neurons.

Experience and the brain



_{The two halves of the brain}

 Work with individuals who have had the

“split-brain” operation (severing the corpus

callosum) to control seizures provides evidence that the two hemispheres are highly

Experience and the brain



_{The two halves of the brain}

 The right hemisphere needs to communicate

with the left in order to name the objects in its visual field.

 The left hemisphere needs the right in order to

synthesize details into a whole picture (e.g., synthesizing the parts of a face into a whole recognizable image).

Figure 3.14

Figure 3.14 The corpus callosum is a large set of axons that convey information between the two hemispheres of the cerebral cortex. (a) A midline view showing the location of the corpus callosum. (b) A horizontal section showing how each axon of the corpus callosum links one spot in the left hemisphere to a corresponding spot in the right hemisphere.

Figure 3.15

Figure 3.15 In the human visual system (viewed here from above), light from either half of the world crosses through the pupils to strike the opposite side of each retina. Axons from the left half of each retina travel to the left hemisphere of the brain; axons from the right half of each retina travel to the right hemisphere of the brain.

The Brain and the Self

We are still learning about the brain, but we

now understand that your brain is composed of

many separate areas with separate abilities.

The Brain and the Self

If you lose part of the brain, you lose part of

your unique experience.

Brain activity and mind are inseparable. One is

the other (the mind-brain debate).

Module 3.2

Nervous System Cells



_Neurons

 You experience yourself as a unitary entity.

 Neuroscientists have demonstrated that that

experience is the product of a nervous system made up of an enormous number of discrete cells.

 The cells that make up your nervous system

Nervous System Cells



_{Neurons and communication}

 Neurons are a unique type of cell that can

receive and transmit information electrochemically.

 Sensory neurons carry information from sense

organs to the central nervous system.

 Neurons in the central nervous system process that

information, interpret it, and then send commands to muscles, glands, and organs.

Figure 3.18

Figure 3.18 Distribution of the estimated 100 billion neurons in the adult human central nervous system. (Based on data of R. W. Williams & Herrup, 1988)

Nervous System Cells



_{The best current estimate is that the human}

nervous system has nearly 100 billion

neurons.



_{And they aren’t the only type of cell in the}

Nervous System Cells



_Glia

 Glia support the neurons in many ways.

 They provide insulation, and remove waste products

and foreign bodies.

 They are 1/10th the size of the neurons, but about

Nervous System Cells



_{Anatomy of a neuron}

 Neurons have a variety of shapes, but they all

have 3 basic parts.

 A cell body that contains the nucleus and most of

the organelles.

 The dendrites, widely branching structures that

receive transmissions from other neurons.

 The axon, a single, long, thin fiber with branches

Figure 3.20

Figure 3.20 The generalized structure of a motor neuron shows the dendrites, the branching structures that receive transmissions from other neurons, and the axon, a single, long, thin, straight fiber with branches near its tip. Axons range in length from 1 millimeter to more than 1 meter and carry information to other cells. Inset: A photomicrograph of a neuron.

Nervous System Cells



_Axons

 The function of the axon is to send the

electrochemical message on to the next cell.

 Most axons transmit information to the dendrites or

cell bodies of neighboring neurons.

 Many axons have a coating of myelin, which speeds

Nervous System Cells



_{Nerve cell growth}

 Neurons do not have a fixed anatomy.

 Researchers have discovered that neurons are

constantly growing and losing branches to dendrites and axons.

 This growth seems to be related to new experiences

Nervous System Cells



_{Action potentials}

 Axons convey information by a combination of

electrical and chemical processes.

 This combination is called an action potential.  An action potential is an excitation that travels

along the axon at a constant strength regardless of the distance it must travel.

Nervous System Cells



_{Action potentials}

 The all-or-none law

 An action potential is an all-or-nothing process – it’s

either happening or not.

 This allows the message to reach the brain at full

Nervous System Cells



_{Action potentials}

 How an action potential works:

 An un-stimulated axon has resting potential.

 Resting potential is an electrical polarization across

the membrane covering the axon.

 A polarized axon has an inside charge that is

Concept Check

If a hamster and a seven-foot-tall human step

on a sharp object, which will respond faster?

Why?

Nervous System Cells



_Synapses

 Communication between neurons occurs at the

synapses.

 A synapse is a specialized junction between two

neurons.

 Chemicals released by one will either excite or

inhibit the other, making it either more or less likely to produce an action potential.

 This activity at the synapses is crucial to everything

Nervous System Cells



_{Synaptic transmission}

 Excitatory messages increase the probability that

the next cell will “fire” - continue to carry the transmission.

 Inhibitory messages decrease the likelihood that

transmission will continue to travel – as in the case of the brain sending a message to inhibit pain in an injured extremity.

Figure 3.24

Figure 3.24 The synapse is the junction of the presynaptic (message-sending) cell and the postsynaptic (message-receiving) cell. At the end of the presynaptic axon is the terminal

Nervous System Cells



_Synapses

 Synaptic communication:

 Each axon has a bulge at the end called a

pre-synaptic ending or a terminal bouton (button)

 When the action potential reaches the terminal

bouton, molecules of a neurotransmitter are released.

 A neurotransmitter is a chemical that is stored in

the neuron. It activates special receptors of other neurons.

Figure 3.25

Nervous System Cells



_Synapses

 Synaptic communication:

 After the message has been sent the

neurotransmitter detaches from the receptor site.

 The neurotransmitter may be reabsorbed by the

axon that released it (a process called reuptake), diffuse away, be metabolized and removed from the body as a waste product, or remain in the synapse and reattach to the receptor.

Concept Check

Learning and environmental challenges

sometimes produce branching in axons and

dendrites of an organism’s neurons. How

would that affect the number of synapses?

Concept Check



_{Dopamine is a neurotransmitter that excites}

postsynaptic neurons. If a drug were injected

into an animal that blocked dopamine from

attaching to its receptors, what would happen

to the postsynaptic neurons?

Neurotransmitters and

Behavior



_{Our understanding of the role of}

neurotransmitters has revolutionized

medicine, particularly psychiatry.

 A drug that can be designed to act on a

particular kind of receptor in the nervous system can also have specific effects on an organism’s functioning and behavior.

 It can be hypothesized that unusual behavior

or problems in functioning may be due to lack or excess of a particular neurotransmitter.

Neurotransmitters and

Behavior



_{Parkinson’s disease}

 Parkinson’s disease- a condition in which the

individual has trouble executing voluntary movements, and has tremors, rigidity, and a depressed mood.

 Has been linked to a decay in a system of axons

Neurotransmitters and

Behavior



_{Parkinson’s disease}

 Dopamine is a neurotransmitter that promotes

activity levels and facilitates movement.

 _{Symptoms of Parkinson’s disease can be}

managed in mild cases with a drug called L-dopa, which is synthesized into dopamine by the neurons.

Neurotransmitters and

Behavior



_{The link is not always so clear though.}

 The symptoms of a disorder such as

attention-deficit disorder or ADD include impulsive,

agitated behavior and a short attention span.

 These symptoms would suggest an oversupply

of dopamine.

 But there doesn’t seem to be any relationship

Concept Check

People suffering from schizophrenia are given

haloperidol, a drug that blocks activity at

dopamine synapses. How would haloperidol

affect a person with Parkinson’s Disease?

Neurotransmitters and

Behavior



_{The neurotransmitter, whether it is in over-,}

under-, or normal supply, is just one part of a

complex system.



_{What alleviates the problem may not}

necessarily tell us what originally caused the

problem.

Module 3.3

The Survey of Abused Drugs

and Their Effects



_{The biological basis of drug abuse and}

addiction

 Nearly all abused and addictive drugs increase

activity at the dopamine receptors in the brain.

 _{These drugs increase the release of dopamine,}

interfere with reuptake, and stimulate neurons that release dopamine or decrease activity of neurons that inhibit its release.

The Survey of Abused Drugs

and Their Effects



_{The biological basis of drug abuse and}

addiction

 The addictive actions of dopamine particularly

work upon a small brain area called the

nucleus accumbens, a central area for attention and habit-formation.

 Activities such as gambling and video game

playing can have the same biological effects.

 Addiction can be thought of as in the person,

Figure 3.30

Figure 3.30 Both legal and illegal drugs operate at the synapse. Drugs can increase the release of neurotransmitters, block their reuptake, or block their receptors.

The Survey of Abused Drugs

and Their Effects

 Stimulants are drugs that boost energy,

heighten alertness, increase activity and produce a pleasant feeling.

 Cocaine and amphetamine are examples of

powerful stimulant drugs

 The net effect of cocaine is to decrease brain

activity, which in turn stimulates behavior.

 Free-base and crack cocaine are forms that

allow the drug to enter the nervous system

more rapidly, thus producing a more powerful “high.”

The Survey of Abused Drugs

and Their Effects

 Ritalin, which is prescribed for children with

ADD, is a strong but slow-acting stimulant.

 Caffeine is a milder and less dangerous

stimulant drug.

 Cigarettes are nicotine delivery devices.

Nicotine is a powerfully addictive stimulant. Smoking temporarily alleviates the feeling of withdrawal.

The Survey of Abused Drugs

and Their Effects

 _Depressants

 _{Depressants are drugs that largely decrease}

physiological arousal.

 The most commonly used and abused

depressants are alcohol and tranquilizers.

 These drugs work by facilitating the

The Survey of Abused Drugs

and Their Effects



_{Depressants – Alcohol}

 Acts as a relaxant when consumed in small

amounts.

 _{In greater amounts, it can increase aggressive}

The Survey of Abused Drugs

and Their Effects



_{Depressants - Alcohol}

 Excessive consumption of alcohol can damage

the liver and other internal organs.

 _{Excessive consumption of alcohol has been}

related to memory impairment and loss of motor control.

 Fetal alcohol syndrome, which can result when

a pregnant woman consumes alcohol, is the number one preventable cause of mental

The Survey of Abused Drugs

and Their Effects

 _{Depressants - Alcohol}

 _{Alcohol abuse and dependence are worldwide}

public health problems.

 Ethnic differences in alcohol consumption have

been related to overall differences in lifespan.

 Native Americans: 12% of deaths caused by

alcohol. vs. 3% in others.

 Life Expectancy: Nat. Am.= 71. Six years lower

The Survey of Abused Drugs

and Their Effects

 _{Depressants – Tranquilizers}

 Medical doctors have prescribed tranquilizers

in the past to help people relax and fall asleep.

 They have also been used to suppress epileptic

seizures.

 Barbiturates, prescribed in the past, proved to

be so addictive and dangerous that it is rarely prescribed today.

 Benzodiazepines, (Valium & others) are milder

drugs used for anxiety management. Also highly addictive.

The Survey of Abused Drugs

and Their Effects

 _Narcotics

 _{Narcotics are drugs that produce drowsiness,}

insensitivity to pain, and overall decreased responsiveness to environmental stimuli.

 Opiates are one common type of narcotic.

 Can be derived naturally from the opium

poppy or synthesized in the laboratory.

 Create a feeling of euphoria.

The Survey of Abused Drugs

and Their Effects



_Narcotics

 Researchers have found that the human brain

produces chemicals called endorphins.

 _{These neurotransmitters bind to opiate}

receptors and stimulate dopamine production.

 Neurons release endorphins when an

The Survey of Abused Drugs

and Their Effects



_Marijuana

 Marijuana is classified as a narcotic, but it

intensifies sensory experiences and in many ways is not like the opiates.

 It has possible medical uses as a mild painkiller

and nausea suppressant.

 It is a dangerous drug to use. As with tobacco,

it poses a risk of lung cancer because it is usually smoked.

The Survey of Abused Drugs

and Their Effects

 _Marijuana

 _{It appears to impair learning and memory. The}

active ingredient in marijuana, THC, is

especially likely to attach to receptors in the hippocampus, where memories are

The Survey of Abused Drugs

and Their Effects

 _{Hallucinogens}

 Drugs that induce sensory distortions and false

sensory experiences are called hallucinogens.

 Peyote is an example of a naturally derived

hallucinogen. It has played an important role in Native American religious ceremonies.

 LSD is a hallucinogen that is artificially

manufactured. It works by altering serotonin

receptors, but we are still unsure how this leads to altered sensory experiences.

 MDMA, also called ecstasy, acts as a stimulant at

low doses and a hallucinogen at high doses. This hallucinogen appears to pose the greatest risk of brain damage to the user.

Table 3.1