Chapter 2

Neuroscience and Behavior

Neural Communication• Biological/neuroscience Psychology

–branch of psychology concerned with the links between biology and behavior

–Want a better understanding of sleep and dreams, depression and schizophrenia, hunger, sex, stress and disease

Neural Communication• Neuron

– a nerve cell– the basic building block of the nervous system

• Dendrite– the bushy, branching extensions of a neuron that

receive messages and conduct impulses toward the cell body

– Brings in info

• 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 that encase the fibers of

many neurons– Speeds up neutral impulses– MS

Neural Communication• Action Potential

– a neural impulse; a brief electrical charge (Ion) that travels down an axon

– Outside the Axon= positive ions– Inside the Axon= negative ions– Even positive and negative= resting potential, which acts like a gate

.– Depolarization= unfreezes or ungates the axon allowing the

message to go through – Refractory period= resting period, when extra atoms are pushed out – Some signals excite and some inhibit

• Threshold – the level of stimulation required to trigger

a neural impulse

– All or nothing

Neural Network

Neural Communication• Synapse Synapse

– 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 cross the synaptic gaps between neurons

– Excite or inhibit – Lock and key– Reuptake

•

•

Neurotransmitters • Each pathway uses different neurotransmitters, each neurotransmitter has a

different function • Acetylcholine ( ACH)

- muscle contraction, learning and memory– Alzheimer's

• Endorphins- – “morphine within” – natural, opiatelike neurotransmitters– linked to pain control and to pleasure

• Dopamine- alertness and movement– Parkinson's– schizophrenia

Neurotransmitters• Serotonin- mood, hunger,sleep and arousal

• depression• Norepinephrine- controls alertness and arousal• Gamma-aminobutryic acid (GABA)- inhibitory

neurotransmitter • Glutamate- A major excitatory neruo., memory

– Migraines– Seizures

Dopamine pathways

How Drugs Effect Neurotransmitters

• Many drugs mimic the neurotransmitter–Agonists excite

–Antagonists inhibit

Neurotransmitter molecule

Receiving cellmembrane

Receptor site onreceiving neuron

Agonist mimicsneurotransmitter

Antagonistblocksneurotransmitter

The Nervous System

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

• The Nervous System –Body’s communication system –2 parts- Central and Peripheral–The Nervous System uses 3 types of

neurons • 1. Sensory • 2. Interneurons• 3. Motor neurons

Central Nervous System

•

Peripheral Nervous System

•

A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord

A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord

A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord

A. Central nervous system B. Peripheral nervous systemB1. Somatic nervous systemB2. Autonomic nervous system 1. Cerebrum2. Brainstem3. Cerebellum4. Spinal cord

The Peripheral System• 2 components

–1. Somatic Nervous SystemSomatic Nervous System- controls our skeletal muscles

–2.Autonomic Nervous SystemAutonomic Nervous System- glands,muscles of our internal organs

–Heartbeat, digestion, hormones –1. Sympathetic Nervous SystemSympathetic Nervous System- defense actions

( increases heartbeat, muscles contract…..)–2. ParasympatheticParasympathetic- it conserves energy

Central Nervous System ( CNS)

• Spinal Cord and Brain

• Spinal Cord connects peripheral system to the brain

• Reflexes

Skinreceptors

Muscle

Sensory neuron(incoming information)

Motor neuron(outgoing information)

Brain

Interneuron

Spinal cord

The Brain

Tools of Discovery • Manipulating the brain –

• Lesions• electromagnetic charges• chemical and magnetic stimulation

• Clinical Observations- looking at damaged brains

• Recording Electrical Activity EEG ( electroencephslogram)

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

EEG

Tools of Discovery• Neuroimaging-

– CT ( Computed tomography) Scan- • X- Ray photographs

– PET ( Positron emission tomography) Scan• Looks at sugar glucose to determine brain activity

– “HOT SPOTS”

– MRI- ( Magnetic Resonance Imaging) • generated images that distinguish among different types

of soft tissue; allows us to see structures within the brain.

PET Scan

PET Scan

MRI

The Brain

Lower Level Brain Structure

•

Lower Brain

Lower Brain-

• performs life saving operations freeing the higher brain regions to think, dream, memorize..

• We are unaware of most of its functions

Lower Level Brain StructureThe Brainstem

1. Brainstem-• where spinal cord enters the skull• Crossover point for nerves

• responsible for automatic survival functions

2. Medulla- Heartbeat and breathing

Lower Level Brain StructureThe Brainstem3. Reticular Formation-

• Filter and relay station• Controls arousal

4. Thalamus-

• Sensory input station,except smell

• Receives higher brains replies• Controls electrical cycles. Slows

during sleep;speeds up while awake

•

Lower Level Brain StructureThe Brainstem

• 5. The Cerebellum

• Coordinates voluntary movements –Balancing, walking……….

• Nonverbal voluntary movement

• 6. Pons– Regulates sleep

The Limbic System

•

The Limbic System

–associated with emotions such as fear and aggression and drives such as those for food and sex

–includes the hippocampus, amygdala, and hypothalamus.

The Limbic System

• 1. Hippocampus-

• Processes memory

• Forms new memories

• 2. Amygdala-

• Aggression and fear

The Limbic System• 3. Hypothalamus-

– Controls pituitary gland (hormones)

– directs several maintenance activities• eating• drinking• body temperature

– Triggers autonomic nervous system– Pleasure Center– Reward Deficiency Syndrome- alcoholism, binge

drinking, drug abuse

Psychosurgery?

• What is psychosurgery?

The Cerebral Cortex• Thin layer covering your cerebral

hemispheres- wrinkly thing

• Neural cells

• Controls body and info

• The bigger the better

The Cerebral CortexStructure and Functions

1. Each hemisphere is divided up into 4 lobes• Frontal• Occipital• Temporal• Parietal

2. Glial Cells- -

• neural nannies• Support the 22 billion nerve cells

The Cerebral Cortex

1. Frontal Lobe- speaking, muscle movement, making plans, judgments

• Motor Cortex- outgoing messages to the body

The Cerebral Cortex2.Parietal Lobe- sensory cortex

• Sensory Cortex-registers and processes body sensations

• Receives info from skin receptors

• More sensitive= bigger area

3.Occipital Lobe- receives visual from opposite sides

The Cerebral Cortex4.Temporal Lobes- receive auditory

simulation from opposite sides

• Don’t need real sounds

Functional MRI scan of the visual cortex activated by light shown in the subject’s eyes`

Auditorycortex

Visualcortex

The Cerebral Cortex• Association Areas-

areas of the cerebral cortex that are not involved in primary motor or sensory functions

involved in higher mental functions such as learning, remembering, thinking, and speaking

Association Areas• 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 – an area of the left frontal lobe that directs the muscle movements involved in

speech

• Wernicke’s Area – an area of the left temporal lobe involved in language comprehension

• Angular Gyrus-auditory sounds

The Cerebral CortexBrain activity when hearing, seeing, and speaking words

Brain Reorganization

• Plasticity- neural tissue can reorganize in response to damage

•Orgasm in foot

•Most plastic when young

Our Divided Brain• Corpus Callosum

– largest bundle of neural fibers

– connects the two brain hemispheres

– carries messages between the hemispheres

Corpus callosum

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

• “alien hand syndrome”

Hemispheric Differences

• Specialization • Each hemisphere has its own

specialties• Most people are stronger in one

hemisphere • Left- logical, verbal, sequential • Right- emotional, expressive, better at

spatial relations

Handedness

• 90% right handed

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

Neural and Hormonal Systems

• Endocrine System

– the body’s “slow” chemical communication system

– a set of glands that secrete hormones into the bloodstream

Endocrine System

• Hormones– chemical messengers, mostly those

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

– Growth, reproduction, metabolism, mood………

Endocrine System• Adrenal 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

– Increases heart beat, blood pressure, blood sugar….. Gives us energy

Endocrine System

• Pituitary Gland– under the influence of the

hypothalamus, the pituitary regulates growth and controls other endocrine glands

– Master gland

Other Hormones /Glands1. Pineal Gland-

• Produces melatonin • regulates circadian rhythms• Seasonal Affective disorder

2. Thyroid- • Maintains metabolic activities• Lack of thyronixe= mental retardation in

children

3. Pancreas- releases insulin and glucagon which regulates blood sugar

Other Hormones /Glands

• 4. Gonads-

–Testis and Ovaries–Release estrogen and

testosterone