General PsychologyGeneral PsychologyChapter 2 Chapter 2

Neuroscience & BehaviorNeuroscience & Behavior

Sarah RachSarah Rach

• Everything psychological – every idea, Everything psychological – every idea, every mood, every urge – is every mood, every urge – is simultaneously biologicalsimultaneously biological

““To think, feel, or act without a body To think, feel, or act without a body would be like running without would be like running without

legs.”legs.”

Neural CommunicationNeural Communication

• The reason we can study The reason we can study other animalsother animals

• Human brain = monkey Human brain = monkey brainbrain

• Our brains are more complex Our brains are more complex than a rat’s but both follow than a rat’s but both follow the same principlesthe same principles

NeuronsNeurons• NeuronNeuron: a nerve cell – the building block : a nerve cell – the building block

of the nervous systemof the nervous system• DendriteDendrite: bushy, branching extensions of : bushy, branching extensions of

a neuron that receive messages and a neuron that receive messages and conduct impulses toward the cell body conduct impulses toward the cell body (LISTENS)(LISTENS)

• AxonAxon: the extension of a neuron, ending in : the extension of a neuron, ending in branching terminal fibers, through which branching terminal fibers, through which messages pass to other neurons or to messages pass to other neurons or to muscles or glands (SPEAKS)muscles or glands (SPEAKS)• Can be very long (several feet)Can be very long (several feet)• Neuron carrying orders to a leg muscle = Neuron carrying orders to a leg muscle =

basketball attached to a rope 4 miles longbasketball attached to a rope 4 miles long

A Motor NeuronA Motor Neuron

Neurons continued…Neurons continued…

• Action PotentialAction Potential: a neural impulse; a brief electrical : a neural impulse; a brief electrical charge that travels down an axoncharge that travels down an axon

• 2 miles per hour – 200 miles per hour2 miles per hour – 200 miles per hour• Excitatory signalsExcitatory signals: like pushing a neuron’s accelerator: like pushing a neuron’s accelerator• InhibitoryInhibitory: like pushing its break: like pushing its break• ThresholdThreshold: the minimum intensity of a neuron: the minimum intensity of a neuron

• If the excitatory signals minus inhibitory signals exceeds If the excitatory signals minus inhibitory signals exceeds the threshold – the signals combined trigger an action the threshold – the signals combined trigger an action potentialpotential

• All-or-None: increasing the level of stimulation above All-or-None: increasing the level of stimulation above the threshold will not increase the neural impulse’s the threshold will not increase the neural impulse’s intensityintensity• More can be firedMore can be fired• They can fire more oftenThey can fire more often• So we can differentiate between gentle or hard sensationsSo we can differentiate between gentle or hard sensations

How Neurons How Neurons CommunicateCommunicate

• SynapseSynapse: the junction between : the junction between the axon tip of the sending neuron the axon tip of the sending neuron and the dendrite or cell body of the and the dendrite or cell body of the receiving neuronreceiving neuron• The tiny gap at this junction is The tiny gap at this junction is

called the called the synaptic gapsynaptic gap or or cleftcleft• Less than one millionth of an Less than one millionth of an

inch wideinch wide

How Neurons CommunicateHow Neurons Communicate

How Neurons How Neurons CommunicateCommunicate

• Dendrites and axons don’t quite touch…Dendrites and axons don’t quite touch…so how do they communicate?so how do they communicate?

• Neurotransmitters: chemical messengers Neurotransmitters: chemical messengers that traverse the synaptic gaps between that traverse the synaptic gaps between neuronsneurons• When released by the sending neuron, When released by the sending neuron,

neurotransmitters travel across the synapse neurotransmitters travel across the synapse and bind to receptor sites on the receiving and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron, thereby influencing whether that neuron will generate an impulse neuron will generate an impulse

• Reuptake: the sending neuron normally Reuptake: the sending neuron normally reabsorbs excess neurotransmitter molecules reabsorbs excess neurotransmitter molecules

Neurotransmitters Neurotransmitters • Acetylcholine (Ach): one of the best-understood Acetylcholine (Ach): one of the best-understood

neurotransmittersneurotransmitters• Is the messenger at every junction between a motor Is the messenger at every junction between a motor

neuron and skeleton muscleneuron and skeleton muscle• When Ach is released to our muscle cells, the muscle When Ach is released to our muscle cells, the muscle

contractscontracts• Endorphins (Endorphins (endendogenous produced within ogenous produced within

mmorphine)orphine)• Natural opiates released in response to pain and Natural opiates released in response to pain and

vigorous exercisevigorous exercise• ““runner’s high”runner’s high”• Painkilling effects of acupuncturePainkilling effects of acupuncture• Indifference to pain in some severely injured peopleIndifference to pain in some severely injured people

Drugs & Chemicals Affect Drugs & Chemicals Affect on Neurotransmitterson Neurotransmitters

• Agonists: ExciteAgonists: Excite• similar enough to a neurotransmitter to mimic its effects similar enough to a neurotransmitter to mimic its effects

or it may block the neurotransmitter’s reuptakeor it may block the neurotransmitter’s reuptake• Antagonists: inhibitAntagonists: inhibit

• Inhibit a neurotransmitter’s release from the sending Inhibit a neurotransmitter’s release from the sending neuronneuron

• Others are enough like the neurotransmitter to occupy Others are enough like the neurotransmitter to occupy its receptor site and block its effect, but are not similar its receptor site and block its effect, but are not similar enough to stimulate the receptorenough to stimulate the receptor

• Foreign coins that fit into, but won’t operate, a pop or Foreign coins that fit into, but won’t operate, a pop or candy machinecandy machine

• Blood-Brain Barrier: fences out unwanted Blood-Brain Barrier: fences out unwanted chemicals circulating in the bloodchemicals circulating in the blood• Makes it difficult to create new drugs to be used to treat Makes it difficult to create new drugs to be used to treat

disorders because they can’t cross the barrierdisorders because they can’t cross the barrier

The Nervous SystemThe Nervous System

• Central Nervous Central Nervous System (CNS)System (CNS)• Brain and spinal cordBrain and spinal cord

• Peripheral Nervous Peripheral Nervous System (PNS)System (PNS)• Links the central nervous Links the central nervous

system with the body’s system with the body’s sensory receptors, sensory receptors, muscles, and glandsmuscles, and glands

• NervesNerves• Neural “cables” Neural “cables”

containing many axonscontaining many axons

Information travels in the nervous Information travels in the nervous system through three types of system through three types of

neuronsneurons

• Sensory Neurons – carry messages Sensory Neurons – carry messages from the body’s tissues and sensory from the body’s tissues and sensory organs inward to the brain and spinal organs inward to the brain and spinal cord, for processingcord, for processing

• Motor Neurons – neurons that carry Motor Neurons – neurons that carry outgoing information from the central outgoing information from the central nervous system to the muscles and nervous system to the muscles and glandsglands

• Interneurons – central nervous system Interneurons – central nervous system neurons that internally communicate neurons that internally communicate and intervene between the sensory and intervene between the sensory inputs and motor outputsinputs and motor outputs

Peripheral Nervous Peripheral Nervous SystemSystem

Peripheral Nervous Peripheral Nervous SystemSystem

• Somatic Nervous SystemSomatic Nervous System• Enables voluntary control of our skeletal Enables voluntary control of our skeletal

• Autonomic Nervous SystemAutonomic Nervous System• Controls our glands and the muscles of our internal Controls our glands and the muscles of our internal

organs (glandular activity, heartbeat, digestion)organs (glandular activity, heartbeat, digestion)• Automatic pilot (autonomously) – but may be Automatic pilot (autonomously) – but may be

consciously overridden consciously overridden • Sympathetic: arouses and expends energy – gets Sympathetic: arouses and expends energy – gets

your ready for actionyour ready for action• Accelerate your heartbeat, raise your blood pressure, Accelerate your heartbeat, raise your blood pressure,

slow your digestion, raise you blood sugar, cool you slow your digestion, raise you blood sugar, cool you with perspirationwith perspiration

• Parasympathetic: conserves energy as it calms you Parasympathetic: conserves energy as it calms you • Decreasing your heartbeat, lowering your blood sugar, Decreasing your heartbeat, lowering your blood sugar,

etc.etc.• Work together to keep us in a steady internal stateWork together to keep us in a steady internal state

Central Nervous SystemCentral Nervous System

• Neural networksNeural networks• neurons cluster into work groupsneurons cluster into work groups• So they can have fast, short connectionsSo they can have fast, short connections

• ReflexesReflexes• Simple, automatic response to a sensory Simple, automatic response to a sensory

stimulus, such as the knee-jerk responsestimulus, such as the knee-jerk response• Pain reflex – hand will jerk from a flame Pain reflex – hand will jerk from a flame

before your brain receives and responds before your brain receives and responds to the information that causes you to feel to the information that causes you to feel painpain

Endocrine SystemEndocrine System• The body’s “slow” The body’s “slow”

chemical chemical communication communication system; a set of system; a set of glands that secrete glands that secrete hormones into the hormones into the bloodstreambloodstream

• HormonesHormones• Travel through the Travel through the

bloodstream and bloodstream and affect other tissues, affect other tissues, including the brainincluding the brain

• Influence our Influence our interest in sex, food, interest in sex, food, and aggressionand aggression

Influential GlandsInfluential Glands• Adrenal Glands:Adrenal Glands:

• Epinephrine (adrenaline)Epinephrine (adrenaline)• Norepinephrine (noradrenaline)Norepinephrine (noradrenaline)• Increase heart rate, blood pressure, blood sugar – Increase heart rate, blood pressure, blood sugar –

create a surge of excitement that can linger a whilecreate a surge of excitement that can linger a while• Pituitary Gland:Pituitary Gland:

• Most influential glandMost influential gland• Pea-sized structure located in the core of the brainPea-sized structure located in the core of the brain• Controlled by an adjacent brain area (hypothalamus)Controlled by an adjacent brain area (hypothalamus)• Releases hormones that influence growthReleases hormones that influence growth• Also influence the release of hormones by other Also influence the release of hormones by other

endocrine glandsendocrine glands

The BrainThe Brain

• When we’re thinking about our When we’re thinking about our brain, we’re thinking brain, we’re thinking withwith our brain our brain

• The mind is what the brain doesThe mind is what the brain does

Older Brain StructuresOlder Brain Structures

• BrainstemBrainstem• The brain’s basementThe brain’s basement• Oldest and innermost regionOldest and innermost region

• MedullaMedulla• Where the spinal cord enters Where the spinal cord enters

the skull and swells slightlythe skull and swells slightly• Controls your heartbeat and Controls your heartbeat and

breathingbreathing• PonsPons

• Just above the medullaJust above the medulla• Helps coordinate movementsHelps coordinate movements

More older brain More older brain structures…structures…

• ThalamusThalamus• A joined pair of egg-shaped structuresA joined pair of egg-shaped structures• Receives information from all the senses except smell and routes it to the brain regions that deal with seeing, hearing, tasting, and Receives information from all the senses except smell and routes it to the brain regions that deal with seeing, hearing, tasting, and

touchingtouching• Receives some of the higher brain’s replies, which it then directs to the medulla and to the cerebellumReceives some of the higher brain’s replies, which it then directs to the medulla and to the cerebellum

• Reticular Formation• Inside the brainstem, between your ears• Finger shaped network of neurons that extends from the spinal cord right up to the thalamus • Filters incoming stimuli and relays important information to other areas of the brain• Is involved in arousal

Older brain structuresOlder brain structures

• CerebellumCerebellum• Means “little brain”Means “little brain”• Extends from the rear of the Extends from the rear of the

brainstembrainstem• Base-ball sizedBase-ball sized• Enables one type of nonverbal Enables one type of nonverbal

learning and memorylearning and memory• Helps us judge time, modulate our Helps us judge time, modulate our

emotions, and discriminate sounds emotions, and discriminate sounds and texturesand textures

• Coordinates voluntary movementCoordinates voluntary movement• Note: the older brain functions all Note: the older brain functions all

occur without any conscious occur without any conscious efforteffort

• Our brain processes most Our brain processes most information outside of our information outside of our awarenessawareness

Limbic SystemLimbic System • Doughnut-shapedDoughnut-shaped• Links to emotions (fear and Links to emotions (fear and

anger) and to basic motives anger) and to basic motives (food and sex)(food and sex)

• AmygdalaAmygdala• Two lima bean-sized neural Two lima bean-sized neural

clustersclusters• Influence aggression and fearInfluence aggression and fear• Removed in an ill-tempered Removed in an ill-tempered

monkeymonkey• Turned very mellowTurned very mellow

• Stimulated in a domestic catStimulated in a domestic cat• Hissing, prepares to attackHissing, prepares to attack• Moved a bit – cowers from a Moved a bit – cowers from a

mousemouse

• HypothalamusHypothalamus• Hypo = below (the thalamus)Hypo = below (the thalamus)• Some parts influence hunger, Some parts influence hunger,

thirst, body temperature, thirst, body temperature, sexual behaviorsexual behavior

• Reward centersReward centers• Reward deficiency syndromeReward deficiency syndrome

Cerebral CortexCerebral Cortex

• Thin surface layer of Thin surface layer of interconnected neural cellsinterconnected neural cells

• Your body’s ultimate control and Your body’s ultimate control and information-processing centerinformation-processing center

• Contains 20-23 billion nerve cells Contains 20-23 billion nerve cells • 300 trillion synaptic connections300 trillion synaptic connections

““being human takes a lot of nerve”being human takes a lot of nerve”

Functions of the CortexFunctions of the Cortex

• Motor FunctionsMotor Functions• Motor cortex – runs from ear-to-ear across Motor cortex – runs from ear-to-ear across

the top of the headthe top of the head• Stimulating parts of the brain in the left or Stimulating parts of the brain in the left or

right hemisphere caused movements of right hemisphere caused movements of specific body parts on the specific body parts on the oppositeopposite side of side of the bodythe body

• Areas of the body requiring precise control Areas of the body requiring precise control (fingers, mouth) occupy the greatest (fingers, mouth) occupy the greatest amount of cortical spaceamount of cortical space

Functions of the CortexFunctions of the Cortex

• Sensory FunctionsSensory Functions• Parallel to the motor cortex & just Parallel to the motor cortex & just

behind the front of the parietal lobesbehind the front of the parietal lobes• Specializes in receiving information Specializes in receiving information

from the skin senses and from the from the skin senses and from the movement of body partsmovement of body parts

Association AreasAssociation Areas

• Three-fourths of the think wrinkled Three-fourths of the think wrinkled layer of the cerebral cortex layer of the cerebral cortex

• Neurons in this area integrate Neurons in this area integrate information, linking sensory inputs information, linking sensory inputs with stored memorieswith stored memories

• Association areas are found in all Association areas are found in all four lobesfour lobes

Association AreasAssociation Areas

• More intelligent animals have More intelligent animals have increased “uncommitted” or increased “uncommitted” or association areas of the cortexassociation areas of the cortex

Language: Language: Specialization & Integration Specialization & Integration

• AphasiaAphasia• Impaired use of languageImpaired use of language• Some people with this can speak fluently but cannot Some people with this can speak fluently but cannot

read read • Some can write but not read, read but not write, read Some can write but not read, read but not write, read

numbers but not lettersnumbers but not letters• Broca’s AreaBroca’s Area

• A specific area of the left frontal lobe, where if damage A specific area of the left frontal lobe, where if damage occurs, muscle movements involved in speech are occurs, muscle movements involved in speech are impactedimpacted

• Struggle to form words, yet could often sing familiar Struggle to form words, yet could often sing familiar songs with easesongs with ease

• Wenicke’s AreaWenicke’s Area• A specific area of the left temporal lob, where if damage A specific area of the left temporal lob, where if damage

occurs, people could only speak meaningless words and occurs, people could only speak meaningless words and were unable to comprehend others’ wordswere unable to comprehend others’ words

The Brain’s PlasticityThe Brain’s Plasticity

• Plasticity – its ability to modify itself after Plasticity – its ability to modify itself after some types of damagesome types of damage

• Some neural tissue can Some neural tissue can reorganizereorganize in response in response to damageto damage

• Most plastic when we are young childrenMost plastic when we are young children• If a blind person uses one finger to read If a blind person uses one finger to read

Braille, the brain area dedicated to that finger Braille, the brain area dedicated to that finger expands as the sense of touch invades the expands as the sense of touch invades the visual cortex that normally helps people seevisual cortex that normally helps people see

• Lose a finger and the sensory cortex that Lose a finger and the sensory cortex that received its input will begin to receive input received its input will begin to receive input from the adjacent fingers, which then become from the adjacent fingers, which then become more sensitivemore sensitive

• Adult mice and humans can also generate new Adult mice and humans can also generate new brain cells brain cells

Splitting the BrainSplitting the Brain

• The brain’s two sides serve differing functionsThe brain’s two sides serve differing functions• Lateralization – hemispheric specializationLateralization – hemispheric specialization• Corpus callosum – wide band of axon fibers Corpus callosum – wide band of axon fibers

connecting the two hemispheres and carrying connecting the two hemispheres and carrying messages between themmessages between them

• Split brained people are surprisingly normal – their Split brained people are surprisingly normal – their personality and intellect hardly affectedpersonality and intellect hardly affected

Left HemisphereLeft Hemisphere

Information Information from the rightfrom the rightvisual field visual field comes herecomes here

Speech is controlled Speech is controlled here – they will say here – they will say what they saw in what they saw in

the the right visual fieldright visual field

Right Hemisphere

Information from the left visual field comes here

Controls the left hand – will point to the word that they saw in their left visual field

Hemispheric DifferencesHemispheric Differences• Right HemisphereRight Hemisphere

• Perceptual tasks performed will cause brain waves, Perceptual tasks performed will cause brain waves, blood flow, and glucose consumption to increase, blood flow, and glucose consumption to increase, which shows activity in the right hemispherewhich shows activity in the right hemisphere

• Excels in making inferences based on languageExcels in making inferences based on language• Left HemisphereLeft Hemisphere

• Speaking or calculating – will increase activity in the Speaking or calculating – will increase activity in the left hemisphereleft hemisphere

• Adept to making quick, literal interpretations of Adept to making quick, literal interpretations of languagelanguage

• Deaf people are enabled to process sign language Deaf people are enabled to process sign language herehere

• Just as hearing people use the left hemisphere to Just as hearing people use the left hemisphere to process speech, deaf people use the left hemisphere to process speech, deaf people use the left hemisphere to read signsread signs

• To the brain, language is language, whether it is spoken or To the brain, language is language, whether it is spoken or signedsigned

Which way is she Which way is she spinning?spinning?

• If you see her If you see her spinning to the spinning to the right, then your right, then your right brain is right brain is working and if working and if you see her you see her spinning to the spinning to the left, then your left, then your left brain is left brain is workingworking

Just for fun…Just for fun…