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In This Chapter

The neuron

The nervous system and the endocrine system

The brain

An Intriguing Puzzle

Neuroscience

• Scientific study of the brain and nervous system

Connectome

• Totality of connections between neurons in the nervous system

The NeuronThe 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- Support neurons by disposing of waste products

of neurons, keeping their chemical environment stable, and insulating them

The Structure of a Neuron

• Dendrites- Include fibers that project out of the cell body, receiving

information from other neurons

• Cell body- Contains the nucleus of the cell and other biological

machinery to keep the cell alive

• Axon- Transmits messages through the neuron

• 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 within neuron is electrical

Communication between neurons

is chemical

The Electrical Impulse: Information from the Dendrites

Excitatory (telling neuron to generate an electrical impulse)

Inhibitory (telling neuron not to generate an electrical impulse)

The Electrical Impulse

• Myelin sheath- Insulating layer of fatty white substance that

encases the axon- Allows electrical message to be transmitted

faster within the neuron- Is responsible for distinction between brain white

and gray matter- Slows electrical impulses when damaged

Chemical Communication between Neurons

• Neurotransmitters– Are contained in axon terminals– Are naturally occurring chemicals in the nervous system– Specialize in transmitting information between neurons

• Synaptic gap– Is a small gap across which neurotransmitters are sent,

allowing neurons to communicate– Is found between axon terminals of one neuron and

dendrites of another neuron

Synaptic Communication Between Neurons

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 (fMRI) detects active areas of the brain by

highlighting those areas that require

more oxygen

Neurotransmitters, Drugs, and Poisons

Agonists• Drugs and poisons that

increase the activity of one or more neurotransmitters

Antagonists• Drugs and poisons that

decrease the activity of one or more neurotransmitters

Neurotransmitters

Acetylcholine (ACh)

Dopamine

Serotonin and norepinephrine

GABA

Glutamate

Endorphins

Acetylcholine (ACh)

Botulinum poison (botulin)

Curare

Black widow spider venom

Dopamine

Dopamine systems in brain

L-Dopa

Anti-psychotic drugs

Amphetamine

Cocaine

Serotonin and Norepinephrine

• Selective serotonin reuptake inhibitors (SSRIs)- Antidepressant drugs that work by blocking the

reuptake of serotonin- Prozac, Paxil, and Zoloft

• Selective serotonin and norepinephrine reuptake inhibitors (SSNRIs)- Antidepressant drugs that work by blocking the

reuptake of serotonin and norepinephrine- Cymbalta, Pristiq, and Effexor

GABA and Glutamate

• Anti-anxiety drugs- Are agonists for GABA

• Glutamate- Is involved in memory storage and pain

perception- Excessive glutamate can lead to neuron death;

deficient glutamate has been linked to schizophrenia

Endorphins

• Morphine and heroin- Are agonists that bind to receptor sites, thereby

increasing endorphin activity- Trigger brain's reward centers, causing release of

dopamine

Neurotransmitters and Some of Their Functions

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 and Its Major Subdivisions

Types of Neurons in the Nervous System

• Interneurons- Integrate information within the CNS through their

communication with each other and between sensory and motor neurons in the spinal cord

• Sensory neurons- Carry information to the central nervous system

from sensory receptors, muscles, and glands

• Motor neurons- Carry movement commands from the central

nervous system to the rest of the body

The Central Nervous System (CNS)

Central Nervous System

Spinal cord

Conduits for incoming sensory data and

outgoing movement commands

Provides for spinal reflexes

BrainControl center

for entire nervous system

The Peripheral Nervous System (PNS)

• PNS- 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

PNS consists of two parts

Somatic (or skeletal) nervous

system

Autonomic nervous system

Sympathetic nervous system

Parasympathetic nervous system

The Endocrine Glandular System

• Endocrine glandular system- Works with the autonomic nervous system in

response to stress- Secretes hormones- Plays a role in basic behaviors and bodily

functions such as sex, eating, metabolism, reproduction, and growth

The Endocrine Glandular System

• Endocrine glands- Are controlled by the hypothalamus which

controls the pituitary gland

• Pituitary gland- Releases hormones essential for human growth- Directs other glands to release their hormones

The Endocrine Glandular System

• Thyroid gland- Affects growth and maturation

• Adrenal glands- Are involved in metabolism and help trigger the “fight

or flight” response with commands from the autonomic nervous system

• Pancreas- Is involved in digestion and maintaining blood-sugar

levels

The Endocrine Glandular System

Emotions and the Autonomic Nervous System

• Emotion involves- Complex psychological state- Physiological arousal- Outward behavioral expression of the emotion- Cognitive appraisal of the situation to determine

the specific emotion and its intensity

The Three Components of Emotion

• Physical component- Includes the “fight or flight” response of the autonomic nervous

system- Involves increase in heart rate and breathing, blood pressure

surges, sweating, pupil dilation, slowing of digestion

• Behavioral component- Is the product of motor neurons- Involves facial-feedback hypothesis which assumes that the facial

muscles send messages to the brain, allowing the brain to determine which emotion is being experienced

• Cognitive component- Includes an appraisal of the situation to determine what emotion we

are experiencing

Theories of Emotion

Theories

Commonsense theory

James-Lange theory

Cannon-Bard theory

Schachter-Singer Two-Factor theory

Theories of Emotion: Commonsense Explanation

Proposes that the subjective experience of the emotion triggers the

physiological arousal and behavioral response

Contends that cognitive recognition of

dangerous situation prompts emotional feeling that arouses autonomic nervous

system

James-Lange Theory

Autonomic nervous system physiological

arousal is a response to a

stimulus

Such a physiological response is

subsequently interpreted as the

emotion

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Cannon-Bard Theory

Brain produces the emotional feeling

Autonomic nervous system produces the physiological response

Motor neurons produce the behavioral response

Emotion-provoking stimulus sends

messages to both the peripheral nervous

system and the brain

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Schachter-Singer Two-Factor Theory

Physiological arousal tells us how

intense the emotion is

Cognitive appraisal of the entire situation allows us to identify

the emotion, leading to the emotional feeling

Two important determinants of emotion

Integrating the Theories

• LeDoux (1996, 2000)- Different brain systems exists for different

emotions

• Examples- Fear does not require higher-level cognitive

processing and is generated almost instantaneously by the amygdala

- Love or guilt do not require instantaneous responding for survival and 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

Going Up the Brain Stem: The Central Core

Brain stemMedulla

Reticular formation

Cerebellum

ThalamusBasal ganglia

Basal ganglia

Central Core Structures and Functions

The Limbic System

• Limbic system- Plays a role in survival, memory, and emotions

• Parts- Hypothalamus - Hippocampus - Amygdala

The Limbic System

Limbic System Structures and Functions

Processing in the Cerebral Cortex

• Cerebral cortex- Most important brain

structure- Information

processing center for nervous system

- Center for all higher-level cognitive processing

- Site of hemispheric communication

Brain Lobes

• Frontal lobe- Area in the front of each hemisphere and in front of

central fissure and above lateral fissure

• Parietal lobe- Area located behind central fissure and above

lateral fissure

• Temporal lobe- Located beneath the lateral fissure

• Occipital lobe- Located in the lower back of each hemisphere

The Four Lobes and the Sensory-Motor Processing Areas

The Motor Cortex

• Frontal lobe strip of cortex- Directly in front of central fissure in each

hemisphere- Allows movement in different parts of the body- Each hemisphere controls voluntary movement

of the opposite side of the body- 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

• Parietal lobe strip of cortex- Directly behind central fissure in each

hemisphere- 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

The Visual Cortex and the Auditory Cortex

• Visual cortex- Located in occipital lobes at back of hemispheres

• Auditory cortex - Located in temporal lobes- Contains primary areas- Passes 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

A Matter of Teamwork!

• McGurk effect- Demonstrates that the brain integrates visual and

auditory information when processing spoken language

- Arises out of conflicting auditory and visual information

Association Cortex

• Association cortex- Involves secondary cortical processing

areas but includes about 70 percent of cortex- Includes higher-level processing such as

decision making, reasoning, perception, speech, and language occurs

The Four Cerebral Lobes

The Case of Phineas Gage

• Phineas Gage - Railroad worker who

survived when a metal tamping iron flew through his left cheek and head, exiting through his frontal lobes

• Results- He became irresponsible,

impulsive, disorderly, indecisive, and began cursing

- Lead neuroscientists to think the frontal lobes are important in such behaviors

Phineas Gage's doctor had this picture of the tamping iron and Phineas's skull taken in 1868 to document the case.

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The Case of Eduardo Leite

• Construction worker in Brazil who was impaled by falling metal bar

• Bar entered in front of the motor cortex in the right hemisphere and exited the right frontal lobe just above the right eye through a “non-eloquent” area of brain

Association Cortex: Language

• Broca's area- Located in left frontal lobe- Is responsible for fluent speech production- When damaged, fluent speech generation is

damaged, but comprehension is left intact- Houses singing and musical abilities

• Wernicke's area - Located in the temporal lobe- Is responsible for the comprehension of speech and

reading

Broca's Area and Wernicke's Area

Einstein's Brain

• Harvey kept Einstein's brain for many years.

• Later research- Unexceptional size but

unusual morphology- Expanded prefrontal

cortex, unusual parietal lobes, and other differences in complexity and patterns of convolusions

Dr. Thomas Harvey with a jar containing pieces of Albert Einstein's brain.

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Specializations of the Left and Right Hemispheres

Studying the two hemispheres • Light waves from the left visual field go to the right half

of each eye and connect with the right hemisphere.

• Light waves from the right visual field go to the left half of each eye and connect with the left hemisphere.

Pathways for Processing Information in the Left and Right Visual Fields

• Half of the fibers from each eye cross over at the optic chiasm to go to the opposite hemisphere

• The right half in the left eye go to the right hemisphere and the left half in the right eye go to the left hemisphere.

Studying the Two Hemispheres

• Sperry- Led most of the

early split-brain research and in 1981 won the Nobel Prize in Physiology or Medicine for his discoveries concerning the functional specializations of the cerebral hemispheres

• Gazzaniga- Sperry's

student - Conducted the first

studies with human split-brain participants in the early 1960s

• Bogen- Continued this line of

inquiry for the past five decades

Studying the Two Hemispheres

• Split-brained people- Information cannot transfer between

hemispheres because the corpus callosum has been severed

- Can only identify information orally when it is presented briefly in the right visual field and thus processing in the left hemisphere

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

Sample Hierarchical Stimulus and Recall Results for Such Stimuli by Brain-Damaged Patients

a) The sample hierarchical stimulus is a capital H made up of little As.

b) Patients with right hemisphere damage (dependent on the left hemisphere) could remember the details of the hierarchical stimulus (the As) but not the overall pattern (H).

c) Patients with left hemisphere damage (dependent upon the right hemisphere) could remember the overall pattern (H) but not its details (the As).

True or False?

It is not very accurate to say someone is “left-brained” or “right-brained”?

Consciousness and the Sleeping Brain

• Consciousness- Person's subjective awareness of both their inner

thinking and feeling and their external environment

• Five stages of sleep can be determined by use of an electroencephalogram (EEG)- 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; sleep spindles

Stage 3: Transitional sleep; delta waves

Stage 4: Lasts about 30 minutes; active parasympathetic nervous system

Stage 5: REM steep: paradoxical sleep

Five Stages of Sleep

Five Stages of Sleep

REM sleep rebound effect involves a significant increase in the proportion of REM sleep following deprivation of REM sleep

Stages 3 and 4 get shorter with each cycle, and REM and Stage 2 get longer with each cycle

These 5 stages (sleep cycle) repeat themselves about every 90 minutes

The Pattern of Sleep-Stage CyclesDuring a Night's Sleep

• After passing through the first four stages of sleep, we return through Stages 3 and 2 to enter REM sleep

• This completes the first sleep-stage cycle

• As this cycle is repeated throughout a typical night's sleep, the deep sleep stages (3 and 4) get briefer and disappear, and the Stage 2 and REM sleep periods get longer

Why do we sleep and dream?

• Results of sleep deprivation - 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

- 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

Why do we sleep and dream?

• Explanations for dreaming- Neurocognitive theory

• Argues that explaining dreams as our subjective interpretations of random neural firing is too simple

• Contends dreams are meaningful products of our cognitive abilities, with continuity between waking and dreaming cognition

• Suggests developmental differences in dreaming parallel graduate cognitive advances