Neuroscience

Neuroscience

Psychology:

A Concise Introduction

2nd Edition



Richard Griggs

Chapter 2



Prepared by

J. W. Taylor V

The Journey…



 The Neuron

 The Nervous

System and the

Endocrine System

 The Brain

The Neuron

The Structure of a Neuron

How Neurons Communicate

Neurotransmitters,

Drugs, and Poisons

Neurons and Glial Cells

 Neurons are responsible for information

transmission throughout the nervous system

 Glial cells do not directly transmit

information, but instead support neurons in

their work by disposing of waste products of

neurons, keeping their

chemical environment

stable, and insulating

them

The Structure of a Neuron

 Dendrites are the fibers that

project out of the cell body,

receiving information from other

neurons

 The cell body contains the

nucleus of the cell and other

biological machinery to keep the

cell alive

 The axon transmits messages

through the neuron

 The axon terminals are at the

end of the axon and send

messages to a different neuron

The Structure of a Neuron

How Neurons Communicate









Communication Communication

within between

a neuron is neurons is

electrical chemical

The Electrical Impulse



 Information from the dendrites is either

excitatory (telling the neuron to generate an

electrical impulse) or inhibitory (telling the

neuron not to generate an electrical impulse)

 The impulse is an “all or nothing” event, meaning

that there either is or is not an electrical impulse

 Stimuli of varying intensities are encoded by the

quantity of neurons generating impulses and the

number of impulses generated each second by

the neurons

The Electrical Impulse



 The myelin sheath is an insulating layer of

fatty white substance that encases the axon,

allowing electrical message to be transmitted

faster within the neuron

 Damage to the myelin sheath will slow

electrical impulses, and can result in diseases

like multiple sclerosis

Chemical Communication

Between Neurons

 Axon terminals contains sacs of

neurotransmitters

 These neurotransmitters are naturally occurring

chemicals in the nervous system that specialize in

transmitting information between neurons

 Between the axon terminals of one neuron

and the dendrites of another neuron is a

small space called the synaptic gap, across

which neurotransmitters are sent, allowing

neurons to communicate

Brain Scans



 Brain scans work because neurons require

oxygen and other nutrients such as blood

sugar

 Positron Emission Tomography (PET) scans

use a dose of radioactive glucose, which moves

to the more-active areas of the brain

 Functional Magnetic Resonance Imaging

(MRI) detects active areas of the brain by

highlighting those areas that require more

oxygen

Neurotransmitters,

Drugs, and Poisons

Key terms:





Agonists Antagonists







Drugs and poisons Drugs and poisons

that increase the that decrease the

activity of one or more activity of one or more

neurotransmitters neurotransmitters

Neurotransmitters

1. Acetylcholine (ACh) is involved in both learning and

memory and muscle movement

2. Dopmaine impacts our arousal and mood states, thought

processes, and physical movement

3. Serotonin and norepinephrine are neurotransmitters

involved in levels of arousal and mood, and play a major

role in mood disorders such as depression

4. GABA is the main inhibitory neurotransmitter in the

nervous system; glutamate is the main excitatory

neurotransmitter

5. Endorphins are a group of neurotransmitters that are

involved in pain perception and relief

Acetylcholine (ACh)

 Botulinum poison (botulin) is an antagonist that

blocks the release of ACh at muscle junctures,

leading to paralysis and even death

 Curare is an antagonist that paralyzes the body by

occupying the receptor sites for ACh, thereby

preventing ACh from getting in and carrying its

message to a neuron

 Black widow spider venom is an agonist for Ach,

causing the continuous release of ACh, flooding the

synapse

Dopamine

 Low levels are associated

with Parkinson’s disease,

and excessively high levels

are associated with schizophrenia

 L-Dopa is an agonist that increases production of

dopamine

 Anti-psychotic drugs are antagonists that block the

receptor sites for dopamine so that this neurotransmitter

cannot send its messages

 Amphetamine acts as an agonist by stimulating the

release of dopamine from axon terminals

 Cocaine is an agonist that blocks the re-uptake of

dopamine

Serotonin and Norepinephrine



 Some antidepressant drugs work by blocking

the reuptake of serotonin and norepinephine

 Anti-depressant drugs like Prozac, Paxil,

and Zoloft are selective serotonin reuptake

inhibitors

GABA and Glutamate

 Anti-anxiety drugs are agonists for GABA

 Lack of GABA may contribute to epilepsy, a

brain disorder resulting in uncontrolled

movement and convulsions

 Glutamate is involved in memory storage

and pain perception.

 Excessive glutamate can lead to neuron

death; deficient glutamate has been

proposed to explain schizophrenia

Endorphins

 Morphine and heroin are agonists that bind

to receptor sites, thereby increasing

endorphin activity

The Nervous and

Endocrine Systems

The Central Nervous System

The Peripheral Nervous System

The Endocrine Glandular System

Emotions and the

Autonomic Nervous System

Nervous System Subdivisions

Types of Neurons



 Interneurons exist only in the central

nervous system

 Sensory neurons carry information to the

central nervous system from sensory

receptors in the eyes, muscles, and glands

 Motor neurons carry movement commands

from the central nervous system to the rest of

the body

The Central Nervous System

Consists of the spinal cord and the brain

 The spinal cord has two functions



 Conduit for incoming sensory data

and outgoing movement commands

 Provides for spinal reflexes, which

are simple automatic actions not

involving the brain

 The brain is the control center for the

entire nervous system

The Peripheral Nervous System



 Gathers information about the external

environment and the body’s internal

environment for the brain through sensory

neurons

 Serves as the conduit for the brain’s

commands to the rest of the body through

motor neurons

The Peripheral Nervous System

Consists of two parts:

 The somatic (or skeletal) nervous system carries

sensory input from receptors to the CNS and relays

commands from the CNS to the skeletal muscles to control

their movement

 The autonomic nervous system regulates our internal

environment and consists of two parts

 The sympathetic nervous system is in control when we

are very aroused and prepares us for defensive action

(such as running away or fighting)

 The parasympathetic nervous system is in control when

the aroused state ends to return our body to its normal

resting state

The Endocrine Glandular System



 Not part of the nervous system

 Works with the autonomic nervous system in

responding to stress, and plays a role in basic

behaviors and bodily functions such as sex,

eating, metabolism, reproduction, and growth

 Endocrine glands secret hormones, which are

chemicals carried by the bloodstream to target

sites throughout the body

The Endocrine Glandular System

 Endocrine glands are controlled by the

hypothalamus, which controls the most influential

gland, the pituitary

 Releases hormones essential for human growth and that

direct other glands to release their hormones

 Some other glands:

 Thyroid gland affects our growth and maturation

 Adrenal glands are involved in metabolism and help

trigger the “fight or flight” response with commands from

the autonomic nervous system

 The pancreas is involved in digestion and maintaining

blood-sugar levels

The Endocrine Glandular System

Components of Emotion

An emotion is a complex psychological

state that involves three components:





Physical Behavioral Cognitive



A physiological An outward An appraisal of the

state of arousal expression including situation to determine

triggered by the facial expressions, which emotion we are

autonomic movements and experiencing and how

nervous system gestures intensely

Components of Emotion

 The physical component

 Includes the “fight or flight” response of the autonomic nervous

system

 Heart rate and breathing increase, blood pressure surges, start

sweating, pupils dilate, digestion slows

 The behavioral component

 Is the product of motor neurons

 The facial-feedback hypothesis assumes that the facial muscles

send messages to the brain, allowing the brain to determine

which emotion is being experienced

 The cognitive component

 Includes an appraisal of the situation to determine what emotion

we are experiencing

Theories of Emotion



James-Lange Theory







Cannon-Bard Theory





Schachter-Singer

Two-Factor Theory

James-Lange Theory

 Contends that autonomic nervous system

physiological arousal is a response to a stimulus, and

that such a physiological response is subsequently

interpreted as the emotion

 For example, if you are crossing

the street and see a car speeding

toward you, your autonomic

nervous system is aroused (e.g.,

increased heart rate). Based on

this arousal, you interpret the

stimulus as threatening and pick

up your pace across the street.

Cannon-Bard Theory

 Contends that arousal patterns for different

emotions are too physiologically alike to be

able to determine what emotion is being

experienced

 Instead, an emotion-provoking stimulus

sends messages to both the peripheral

nervous system and the brain

 The brain produces the emotional feeling, the

autonomic nervous system produces the

physiological response, and the motor neurons

produce the behavioral response

Schachter-Singer

Two-Factor Theory



 Contends that there are two important

determinants of emotion:

 Physiological arousal tells us how intense the

emotion is

 The cognitive appraisal of the entire situation

allows us to identify the emotion, leading to the

emotional feeling

Integrating the Theories



 LeDoux (1996) contends that there are

different brain systems for different emotions

 Fear, for example, does not require higher-level

cognitive processing and is generated almost

instantaneously by the amygdala

 More complex emotions, however, such as love

or guilt, that do not require instantaneous

responding for survival, may require higher-level

processing

The Brain

Going up the Brain Stem

Processing in the Cerebral Cortex

Specializations of the

Left and Right Hemispheres

Consciousness and

the Sleeping Brain

Case 1: A Landscape Artist

Scenario Neuroanatomy Related Function

Anne the  Left motor cortex  Controls right hand

landscape  Left frontal lobe  Contains motor cortex

artist is  Visual cortex  Used for vision

standing at her

easel, painting  Both occipital lobes  Contain visual cortex

with her right  Auditory cortexes  Used to hear music

hand as she  Both temporal lobes  Contain auditory cortexes

looks out the  Right hemisphere  Spatial ability for painting

window at her  Thalamus  Relays sensory information

garden. She’s

listening to  Frontal lobes  Deciding what to paint

classical  Left sensory cortex  Feeling the paintbrush

music as she  Left parietal lobe  Contains sensory cortex

paints.  Cerebellum  Coordinates moving arm

Case 2: A Professional Wrestler

Scenario Neuroanatomy Related Function

Crazy Eddie, the  Both motor cortexes  Move muscles

professional  Frontal lobes  Contain motor cortexes

wrestler, is in the  Both sensory cortexes  Needed for sense of touch

ring wrestling. The  Parietal lobes  Contain sensory cortexes

 Visual cortexes  Used for vision

crowd is yelling

 Both occipital lobes  Contain visual cortexes

and his is taunting

 Right hemisphere  Spatial ability for wrestling

him. Eddie yells  Wernicke’s area  Understanding taunts

back at his  Left temporal lobe  Contains Wernicke’s area

opponent. The two  Broca’s area  Produces speech (yells)

of them are out of  Left frontal lobe  Contains Broca’s area

breath and  Thalamus  Sensory relay

sweating  Frontal lobes  Decision making & attention

profusely. They  Medulla  Regulates heart and breathing

continue their  Amygdala  Aggression and fear

 Reticular formation  Controls arousal

well-orchestrated

 Cerebellum  Balance and coordination

series of wrestling  Hypothalamus  Regulates temperature

moves.  Hippocampus  Memory for moves

Case 3: A Student



Scenario Neuroanatomy Related Function

Jill is a law  Hippocampus  Remembering and learning

student  Wernicke’s area  Language comprehension

studying for

her exam. She  Left temporal lobe  Contains Wernicke’s area

is reading  Amygdala  Anger and fear about cases

about violent  Frontal lobes  Decision making & attention

rape and

 Hypothalamus  Regulates hunger and thirst

murder cases.

She is snacking  Angular gyrus  Needed for reading

on popcorn

and drinking

coffee.

Source: Sheldon, J. P. (2000). A neuroanatomy teaching activity using case studies and collaboration.

Teaching of Psychology, 27, 126-128.

The Central Core

 The brain stem

 The medulla links the spinal cord to the brain and is involved in

regulating heartbeat, blood pressure, digestion, and swallowing

 The reticular formation is a network of neurons running up the

center of the brain stem and into the thalamus that is involved in

controlling our different levels of arousal and awareness

 The cerebellum is involved in the coordination of our

movements, our sense of balance, and motor and

procedural learning

 The thalamus, located at the top of the brain stem,

serves as a relay station for incoming sensory

information (except smell)

 The basal ganglia are on the outer sides of the thamalus and are

concerned mainly with the initiation and execution of physical

movements

The Central

Core Brain

Structures

The Limbic System



 Plays a role in our survival, memory, and

emotions

 The hypothalamus control the pituitary gland,

the autonomic nervous system, and plays a

major role in regulating basic drives such as

eating, thirst, and sex

 The hippocampus is involved in the formation

of memories

 The amygdala plays a major role in regulating

our emotional experiences, especially fear,

anger, and aggression

The Limbic System

Processing in

the Cerebral Cortex

 The cerebral cortex

is the most important

brain structure, serving

as the information

processing center for

the nervous system

 Is where perception, language, memory, decision

making, and all other higher-level cognitive processing

occur

 Consists of two hemispheres connected by a band of

neurons called the corpus callosum, allowing the two

hemispheres to communicate

Brain Lobes

1. The frontal lobe is the area in the

front of each hemisphere and in front of

the central fissure and above the lateral

fissure

2. The parietal lobe is the area located

behind the central fissure and above the

lateral fissure

3. The temporal lobe is located beneath

the lateral fissure

4. The occipital lobe is located in the

lower back of each hemisphere

The Four Lobes and the

Sensory-Motor Processing Areas

The Motor Cortex

 The frontal lobe strip of cortex, directly in front

of the central fissure in each hemisphere,

allows us to move different parts of our body

 Each hemisphere controls the voluntary

movement of the opposite side of the

body (a contralateral relationship)

 Amount of motor cortex devoted to a

specific body part is related to the

complexity and precision of movement

of which that part is capable

The Somatosensory Cortex

 The parietal lobe strip of cortex, directly

behind the central fissure in each

hemisphere, is where body sensations

of pressure, temperature, limb

position, and pain are processed

 Contralateral relationship

 Amount of sensorimotor cortex devoted

to a body part is directly proportionate to

the sensitivity of that body part

Homunculi for the Motor Cortex

and the Somatosensory Cortex

Visual Cortex

and Auditory Cortex

 The visual cortex is located in the occipital lobes at

the back of the hemispheres

 The auditory cortex is in the temporal lobes

 These primary areas pass the

results of their analyses on to

areas in the other lobes to complete

the brain’s interpretation of the

incoming visual or auditory information

 These secondary cortical processing

areas are part of what is termed the

association cortex

Association Cortex



 Consists of the other 70% of the cortex not

in one of the previously mentioned areas

 This is where the higher-level processing

such as decision making, reasoning,

perception, speech, and language occurs

 All of which require integration of various types

of information

The Case of Phineas Gage

 Phineas Gage was railroad worker

who survived when a metal tamping

iron flew through his left cheek and

head, exiting through his frontal

lobes

 He became irresponsible,

impulsive, disorderly, indecisive,

and cursed, leading neuroscientists

to think the frontal lobes are

important in such behaviors

Language



 Broca’s area, in the left hemisphere’s temporal

lobe, is responsible for fluent speech production

 When damaged, people cannot generate fluent speech,

but can still understand speech easily

 Singing and musical abilities seem to be housed in the

right hemisphere because damage to Broca’s area does

not impair these abilities

 Wernicke’s area is in the left temporal lobe and is

responsible for the comprehension of speech and

reading

Language

Studying the Two Hemispheres

 Light waves from the left visual field go to the

right half of each eye, and light waves from the

right visual field go to the left half of each eye

 The right half of each eye connects with the

right hemisphere, and the left half of each eye

connects with the left hemisphere

Pathways for

Processing

Information

in the Left

and Right

Visual Fields

Studying the Two Hemispheres

 With split-brained people, the information

cannot transfer between hemispheres

because the corpus callosum has been cut

 Split-brain people can only identify

information orally when it is presented

briefly in the right visual field (and thus

processing in the left hemisphere)

 If a spoon was flashed in the left visual

field, split-brained people could not say it

was a spoon

 If the person was blind-folded and told to

find the object from a group of objects

with the left hand, s/he can do this

What we know…

 Left hemisphere

 Language

 Math and logic skills

 More analytical, analyzing wholes into pieces

 Right hemisphere

 Spatial perception

 Solving spatial problems

 Drawing

 Face recognition

What we know…

 Remember, however, that these differences

in hemispheric performance are for people

whose two hemispheres can no longer

communicate

 When normal people are performing a task,

the two hemispheres are constantly

interacting and sharing information

 This is why it is not very accurate to say

someone is “left-brained” or “right-brained”

 Rather, nearly all of us are “whole brained”

Consciousness

and the Sleeping Brain

 Consciousness is a person’s subjective awareness

of both their inner thinking and feeling and their

external environment

 The five stages of sleep were determined by use of

an electroencephalogram (EEG), which records a

real-time graph of a person’s cortical electrical

activity in the brain

 As we slip into sleep and pass through the first four

stages, our brain waves change, in general becoming

progressively slower, larger, and more irregular, especially

in Stages 3 and 4

Five Stages of Sleep

 Stage 1: Lasts about 5 minutes

 Stage 2: Lasts about 20 minutes

 Characterized by sleep spindles, rapid bursts of

mental activity

 Stage 3: Also known as transitional sleep

and is characterized by delta waves, which

are large, slow waves

 Stage 4: Lasts about 30 minutes

 Parasympathetic nervous system is active, as

muscles relax, heartbeat slows, blood pressure

declines, and digestion speeds up

Five Stages of Sleep

 Stage 5: REM (rapid eye movement sleep) occurs

after we leave stage 4 sleep and return through the

earlier stages of sleep

 Called paradoxical sleep because your muscles are relaxed, but

other body systems, including the brain, are active, much like a

waking pattern

 Characterized by very rapid brain waves somewhat like those of

Stage 1 sleep, but one is still sound asleep

 If awakened during REM sleep, people often report having been

dreaming

 Most dreams are emotional and unpleasant, perhaps because

the visual cortex and frontal lobe are inactive during REM sleep;

the limbic system structures are active, however, creating

irrational imagery and emotional experiences of our dream world

 REM sleep accounts for 20–25% of total sleep time

Five

Stages

of Sleep

Five Stages of Sleep



 These 5 stages (the sleep cycle) repeat

themselves about every 90 minutes, with

Stages 3 and 4 getting shorter with each cycle,

and REM and Stage 2 getting longer with each

cycle

 REM sleep rebound effect is a significant

increase in the proportion of REM sleep

following deprivation of REM sleep

Why do we sleep and dream?



 Sleep deprivation results in:

 Impaired concentration and a general bodily feeling of

weakness and discomfort

 Suppression of the immune system, lessening one’s

ability to fight off infection and disease

 Increased vulnerability to accidents

 Increased difficulty in concentrating, studying, and

taking exams

Why do we sleep and dream?



 Explanations for dreaming :

 Sigmund Freud proposed that dreams were

disguised outlets for inner conflicts of our

unconscious mind, a view not accepted by modern

sleep researchers

 The activation-synthesis hypothesis contends that

dreams are merely the sleeping brain’s attempt to

make sense of random neural activity without the

rational interpretation of the frontal lobe