Neural Communication

Biological Psychology branch of psychology concerned with the

links between biology and behavior some biological psychologists call themselves behavioral

neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists

Phrenology (Franz Gall) Study of the bumps on your head Bumps reveal a person’s abilities and

traits

PhrenologyPhrenology

Neural Communication

Neuron a nerve cell the basic building

block of the nervous system Soma

cell body; serves as neuron’s control center

Neural Communication Dendrite

the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

Axon the extension of a neuron, ending in branching

terminal fibers, through which messages are sent to other neurons or to muscles or glands

Myelin [MY-uh-lin] Sheath a layer of fatty cells segmentally encasing the

fibers of many neurons enables vastly greater transmission speed of

neutral impulses

Neural Communication

Neural Communication

Action Potential a neural impulse; a brief electrical

charge that travels down an axon generated by the movement of

positively charged atoms in and out of channels in the axon’s membrane

Threshold the level of stimulation required to

trigger a neural impulse

Neural Communication

Cell body end of axon

Direction of neural impulse: toward axon terminals

Action Potential Within a Neuron

How Neurons Communicate

Neurons communicate by means of an electrical signal called the Action Potential

Action Potentials are based on movements of ions between the outside and inside of the cell

When an Action Potential occurs, a molecular message is sent to neighboring neurons

Resting PotentialResting Potential

► At rest, the inside of the cell is at -70 microvoltsAt rest, the inside of the cell is at -70 microvolts► With inputs to dendrites inside becomes more positive With inputs to dendrites inside becomes more positive ► If resting potential rises above threshold, an action If resting potential rises above threshold, an action

potential starts to travel from cell body down the axonpotential starts to travel from cell body down the axon► Figure shows resting axon being approached by an APFigure shows resting axon being approached by an AP

Depolarization Ahead of Depolarization Ahead of APAP

► AP opens cell membrane to allow sodium (NaAP opens cell membrane to allow sodium (Na++) in ) in ► Inside of cell rapidly becomes more positive than outsideInside of cell rapidly becomes more positive than outside► This depolarization travels down the axon as leading edge This depolarization travels down the axon as leading edge

of the APof the AP

Repolarization follows Repolarization follows

► After depolarization potassium (KAfter depolarization potassium (K++) moves out restoring ) moves out restoring the inside to a negative voltagethe inside to a negative voltage

► This is called This is called repolarizationrepolarization► The rapid depolarization and repolarization produce a The rapid depolarization and repolarization produce a

pattern called a spike dischargepattern called a spike discharge

Finally, HyperpolarizationFinally, Hyperpolarization

► Repolarization leads to a voltage below the resting Repolarization leads to a voltage below the resting potential, called hyperpolarizationpotential, called hyperpolarization

► Now neuron cannot produce a new action potentialNow neuron cannot produce a new action potential► This is the This is the refractory periodrefractory period

Neural Communication Synapse [SIN-aps]

junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron

tiny gap at this junction is called the synaptic gap or cleft

Neurotransmitters chemical messengers that traverse the synaptic

gaps between neurons when released by the sending neuron, neuro-

transmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse

Neurotransmitter Release

Action Potential causes vesicle to open

Neurotransmitter released into synapse

Locks onto receptor molecule in postsynaptic membrane

Neural Communication

Locks and KeysLocks and Keys

Neurotransmitter Neurotransmitter molecules have molecules have specific shapesspecific shapes

When NT binds to When NT binds to receptor, ions enterreceptor, ions enter

Receptor molecules Receptor molecules have binding siteshave binding sites

Some Drugs Work on Some Drugs Work on ReceptorsReceptors

Some drugs are Some drugs are shaped like shaped like neurotransmittersneurotransmitters

AntagonistsAntagonists: fit the : fit the receptor but poorly receptor but poorly and block the NTand block the NT e.g., beta blockerse.g., beta blockers

AgonistsAgonists: fit : fit receptor well and receptor well and act like the NTact like the NT e.g., nicotinee.g., nicotine

Neural Communication

Serotonin Pathways Dopamine Pathways

Dopamine

Involved in movement, attention and learning

Dopamine imbalance also involved in schizophrenia

Loss of dopamine-producing neurons is cause of Parkinson’s disease

Parkinson’s DiseaseParkinson’s Disease

Results from loss of dopamine-producing Results from loss of dopamine-producing neurons neurons

Symptoms includeSymptoms include difficulty starting and stopping voluntary difficulty starting and stopping voluntary

movementsmovements tremors at resttremors at rest stooped posturestooped posture rigidityrigidity poor balancepoor balance

Parkinson’s DiseaseParkinson’s Disease

TreatmentsTreatments L-dopaL-dopa transplants of fetal dopamine-transplants of fetal dopamine-

producing substantia nigra cellsproducing substantia nigra cells adrenal gland transplantsadrenal gland transplants electrical stimulation of the thalamus electrical stimulation of the thalamus

has has been used to stop tremorsbeen used to stop tremors

Serotonin

Involved in sleep Involved in depression

Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect

Excitatory and Inhibitory Messages

Excitatory message— increases the likelihood that the postsynaptic neuron will activate

Inhibitory message— decreases the likelihood that the postsynaptic neuron will activate.

Neural Communication

Neurotransmitter molecule

Receiving cellmembrane

Receptor site onreceiving neuron

Agonist mimicsneurotransmitter

Antagonistblocksneurotransmitter

Acetylcholine

First neurotransmitter discovered Ach is found in all motor neurons It stimulates muscles to contract,

including the heart and stomach muscles

Primary Roles: learning, memory, muscle contractions

Disruption of Acetylcholine Functioning

Curare—blocks ACh receptorsparalysis results

Nerve gases and Black Widow spider venom; too much ACh leads to severe muscle spasms and possible death

Disruptions in ACh Functioning

Cigarettes—nicotine works on ACh receptorscan artificially stimulate skeletal

muscles, leading to slight trembling movements

Alzheimer’s Disease

Deterioration of memory, reasoning, and language skills

Symptoms may be due to loss of ACh neurons

Endorphins Control pain and pleasure Released in response to pain Morphine and codeine work on

endorphin receptors; involved in healing effects of acupuncture

Runner’s high— feeling of pleasure after a long run is due to heavy endorphin release

Norepinephrine

Arousal“Fight or flight” responsePrimary Roles: physical

arousal, learning, memoryDisorders: depression

GABA

Inhibition of brain activity Huntington’s disease involves loss

of neurons in striatum that utilize GABASymptoms:

jerky involuntary movements mental deterioration

Glutamate

Major excitatory neurotransmitterToo much glutamate (and too little

GABA) associated with epileptic seizures

Neural Communication

Summary

• Neuron structure• Action potentials• Synapse• Neurotransmitters• Receptors and ions• Agonists and

antagonists

The Nervous System

Nerves neural “cables” containing many axons part of the peripheral nervous system connect the central nervous system with

muscles, glands, and sense organs

Aron Ralston

Neurons and Synapses

Types of Neurons

Sensory Motor Interneurons

SpinalCord

BrainSensoryNeuron

Sensory NeuronsSensory Neurons

► INPUT INPUT From From sensory organs to the brain and sensory organs to the brain and spinal cordspinal cord

Drawing shows a somatic neuron

Also called AFFERENT NEURONS

SpinalCord

BrainSensoryNeuron

MotorNeuron

Motor NeuronsMotor Neurons

►OUTPUTOUTPUT From the brain and spinal From the brain and spinal cord, to the muscles and glandscord, to the muscles and glands

Also called EFFERENT NEURONS

SpinalCord

BrainSensoryNeuron

MotorNeuron

InterneuronsInterneurons

►Interneurons Interneurons carry carry information information between between other other neurons only neurons only found in the found in the brain and brain and spinal cordspinal cord

The Nervous System Nervous System

the body’s speedy, electrochemical communication system

consists of all the nerve cells of the peripheral and central nervous systems

Peripheral Nervous System (PNS) the sensory and motor neurons that

connect the central nervous system (CNS) to the rest of the body

The Nervous System

Central(brain and

spinal cord)

Nervoussystem

Autonomic (controlsself-regulated action of

internal organs and glands)

Skeletal (controlsvoluntary movements of

skeletal muscles)

Sympathetic (arousing)

Parasympathetic (calming)

Peripheral

The Nervous System Reflex

a simple, automatic, inborn response to a sensory stimulus

Skinreceptors

Muscle

Sensory neuron(incoming information)

Motor neuron(outgoing information)

Brain

Interneuron

Spinal cord

The Nervous System

Somatic Nervous System the division of the peripheral nervous

system that controls the body’s skeletal muscles

Autonomic Nervous System the part of the peripheral nervous

system that controls the glands and the muscles of the internal organs (such as the heart)

The Nervous System

Sympathetic Nervous System division of the autonomic nervous

system that arouses the body, mobilizing its energy in stressful situations

Parasympathetic Nervous System division of the autonomic nervous

system that calms the body, conserving its energy

The Nervous System

The Nervous System

Brain and Spinal Cord

Central Nervous System (CNS) the brain and spinal cord

Brain part of the CNS that plays important roles in

sensation, movement, and information processing.

Spinal Cord plays a role in body reflexes and in

communication between the brain and the peripheral nervous system.

The Nervous System

Neural Networks interconnected

neural cells with experience,

networks can learn, as feedback strengthens or inhibits connections that produce certain results

computer simulations of neural networks show analogous learning

Inputs Outputs

Neurons in the brain connect with one

another to form networks

The brain learns by modifyingcertain connections in response to feedback

The BRAINThe BRAIN

The Brain

Lesion tissue

destruction a brain lesion

is a naturally or experimentally caused destruction of brain tissue

Association Areas Association Areas

Areas of the cerebral cortex that are not involved in primary motor or sensory functions. They are involved in higher mental functions such as learning, remembering, thinking and speaking.

Phineas Gage

Electroencephalogram (EEG)

an amplified recording of the waves of electrical activity that sweep across the brain’s surface

these waves are measured by electrodes placed on the scalp

The Brain CT (computed tomography) Scan also

called CAT a series of x-ray photographs taken from

different angles and combined by computer into a composite representation of a slice through the body; also called CAT scan

PET (positron emission tomography) Scan a visual display of brain activity that detects

where a radioactive form of glucose goes while the brain performs a given task

PET Scan

PET Scan

The Brain

MRI (magnetic resonance imaging) a technique that uses magnetic fields and radio

waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain

Stimulation Electrical stimulation of the brain involves

sending a weak electric current into a brain structure to stimulate it. (It is not painful because the brain has no pain receptors

MRI Scan

The Brain

Brainstem the oldest part and central core of the

brain, beginning where the spinal cord swells as it enters the skull

responsible for automatic survival functions

Developing BrainDeveloping Brain

•Neural tube—beginning of nervous system develops at 2 weeks after conception

•Neurogenesis—development of new neurons

Hindbrain StructuresHindbrain Structures

Cerebellum Cerebellum BrainstemBrainstem

– medullamedulla– reticular reticular

formationformation– ponspons

MedullaMedulla

BreathingBreathing Heart rateHeart rate DigestionDigestion Other vital Other vital

reflexesreflexes– swallowingswallowing– coughingcoughing– vomitingvomiting– sneezingsneezing

PonsPons

Helps coordinate Helps coordinate movements on movements on left and right left and right sides of the bodysides of the body– e.g., postural e.g., postural

reflexes which reflexes which help you help you maintain maintain balance while balance while standing or standing or movingmoving

Reticular FormationReticular Formation

Network of Network of neurons in the neurons in the brainstem brainstem (and (and thalamus)thalamus)

Sleep and Sleep and arousalarousal

AttentionAttention

CerebellumCerebellum

Coordinated, Coordinated, rapid voluntary rapid voluntary movementsmovements– e.g., playing e.g., playing

the piano, the piano, kicking, kicking, throwing, etc.throwing, etc.

Lesions to Lesions to cerebellumcerebellum– jerky, exaggerated jerky, exaggerated

movementsmovements– difficulty walkingdifficulty walking– loss of balanceloss of balance– shaking handsshaking hands

The BrainThe Brain CerebellumCerebellum [sehr-uh-BELL-um[sehr-uh-BELL-um]]

the “little brain” the “little brain” attached to the attached to the rear of the rear of the brainstembrainstem

it helps it helps coordinate coordinate voluntary voluntary movement and movement and balancebalance

Forebrain StructuresForebrain Structures ThalamusThalamus Limbic Limbic

SystemSystem CortexCortex

ThalamusThalamus

Relay station Relay station in brainin brain

Processes Processes most most information information to and from to and from higher brain higher brain centerscenters

The Limbic SystemThe Limbic System

The Limbic SystemThe Limbic System

HypothalamusHypothalamus AmygdalaAmygdala HippocampusHippocampus

The Limbic System

Electrode implanted in reward center

Amygdala and Emotion

Identify emotion from facial expressions

Amygdala damage makes this task difficult

Hypothalamus

Contains nuclei involved in a variety of behaviors sexual behavior hunger, thirst sleep water and salt balance body temperature regulation circadian rhythms role in hormone secretion

Hypothalamus and Hormones

Hypothalamus releases hormones or releasing factors which in turn cause pituitary gland to release its hormones

HippocampusHippocampus

Hippocampus–Hippocampus– structure that structure that contributes to the formation of contributes to the formation of memoriesmemories..

Damage to the hippocampus has Damage to the hippocampus has been implicated in the memory been implicated in the memory loss associated with Alzheimer’s.loss associated with Alzheimer’s.

The Cerebral Cortex

Cerebral Cortex the intricate fabric of

interconnected neural cells that covers the cerebral hemispheres

the body’s ultimate control and information processing center

Glial Cells cells in the nervous system that

support, nourish, and protect neurons

The Cerebral Cortex Frontal Lobes

involved in speaking and muscle movements and in making plans and judgments

Parietal Lobes include the sensory cortex & processes somatic

information Occipital Lobes

include the visual areas, which receive visual information from the opposite visual field

Temporal Lobes include the auditory areas

The Cerebral Cortex

Motor Cortex area at the rear of the frontal lobes that

controls voluntary movements Sensory Cortex

area at the front of the parietal lobes that registers and processes body sensations

The Cerebral Cortex

The Cerebral Cortex

Functional MRI

.......fMRI......... scan shows

the visual cortex activated as the subject looks at faces

Visual and Auditory Cortex

Association Areas More intelligent animals have increased

“uncommitted” or association areas of the cortex

The Cerebral Cortex Aphasia

impairment of language, usually caused by left hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)

Broca’s Area (Disrupts speaking) an area of the left frontal lobe that directs

the muscle movements involved in speech Wernicke’s Area (Disrupts

understanding) an area of the left temporal lobe involved

in language comprehension and expression

Specialization and Integration

Specialization and Integration

Brain activity when hearing, seeing, and speaking words

Brain Reorganization

Plasticitythe brain’s capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development

Brain Reorganization

Hemispherectomy

The surgical removal of an entire cerebral hemisphere

Our Divided Brain

Corpus Callosum large band

of neural fibers

connects the two brain hemispheres

carries messages between the hemispheres

Corpus callosum

Our Divided Brain

The information highway from the eye to the brain

Split Brain

a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them

Split Brain

“Look at the dot.” Two words separatedby a dot are momentarily projected.

“What worddid you see?”

or

“Point withyour left hand to theword you saw.”

Disappearing Southpaws

The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).

The percentage of lefties sharplydeclines with age

10 20 30 40 50 60 70 80 90Age in years

14%

12

10

8

6

4

2

0

Percentage ofleft-handedness

Brain Structures and their Functions

The Endocrine System

Endocrine System the body’s “slow”

chemical communication system

a set of glands that secrete hormones into the bloodstream

Neural and Hormonal Systems

Hormones chemical messengers, mostly those

manufactured by the endocrine glands, that are produced in one tissue and affect another

Pituitary Gland under the influence of the hypothalamus, the

pituitary regulates growth and controls other endocrine glands

The effects of the pituitary are clearly shown here. Entertainer David Frost stands between the

world’s tallest and smallest man.

The tallest man in history was 8 feet 11 inches tall. He died at the age of 22, partly as a result of this defect. The shortest known person was 23 inches tall when she died at the age of 19. Today’s medicines can handle most of these problems if caught earlier enough, but these cases show what happen if the pituitary gland goes awry.

Neural and Hormonal Systems

Oxytocin– stimulates contractions of the uterus during labor and secretion of milk during nursing.

Growth Hormone– stimulates the physical development of bones and muscles.

Neural and Hormonal Systems

Adrenal [ah-DREEN-el] Glands a pair of endocrine glands just above the kidneys secrete the hormones epinephrine (adrenaline) and

norepinephrine (noradrenaline), which help to arouse the body in times of stress

Cortisol– regulates metabolism and response to stress.

Neural and Hormonal Systems

Pancreas Hormones

Insulin– decreases blood sugar

Glucagon– Increases blood sugar

Neural and Hormonal Systems

Thyroid Hormone

Thyroxin– regulates metabolism and growth

Neural and Hormonal Systems

Sex Glands (Gonads)

Female Sex Hormone– Estrogen (Ovary)

Male Sex Hormone– Androgen (Testis)