THE BIOLOGICAL BASES OF BEHAVIOR

What’s actually happening in my body? Processes that happen within your body

without you thinking about them Information travels instantaneously from brain

to body via the nervous system For Instance:

Watching a movie… Stimulus-light from screen-striking your eye Brain interprets light and signals other parts of your

body Sweat glands perspiring, heartbeat quickens,

muscular movements enable hands to find popcorn and put in mouth, then you chew

COMMUNICATION IN THE NERVOUS SYSTEM

Nervous system handles information like the circulatory system handles blood.

COMMUNICATION IN THE NERVOUS SYSTEM

The hardware for messaging: Living tissue composed of cells-two

types of cells GLIA and NEURONS GLIA-cells found throughout nervous

system that provide structural support-literally means glue

NEURONS-individual cells that receive, integrate, and transmit information-most only communicate with other NEURONS-but some carry messages from sensory organs or to muscles (these are the important ones!)

COMMUNICATION IN THE NERVOUS SYSTEM

Common features of NEURONS Soma-cell body, contains cell nucleus

and chemical makeup common to most cells

Dendrites-branch, feeler-like structures that is the part of the NEURON that is special to receive information, carries to cell body

Axon-information travels away from cell body along the Axon. It is a long, thin fiber that transmits signals from Soma to other NEURONS muscles or glands.

COMMUNICATION IN THE NERVOUS SYSTEM

Common features of NEURONS Myelin Sheath-In humans Axons are wrapped in a

white, fatty substance called myelin sheath, which is an insulating material If an Axon’s Myelin Sheath deteriorates its signals

may not transmit effectively-the disease multiple sclerosis (loss of muscle control) is an example of loss of myelin sheath on an axon to muscles

Terminal Buttons-end of an Axon that is a cluster of small knobs that secrete neurotransmitters Chemicals serve as messengers that activate other

NEURONS

COMMUNICATION IN THE NERVOUS SYSTEM

The point at which NEURONS interconnect are called synapses. Synapse-a junction where information is

transmitted from one neuron to another. SUMMARY:

Information is received by the Dendrites, goes to the Soma, along the Axon, and is transmitted to the Dendrites of other cells at meeting points called Synapses.

NEURONS USE ENERGY TO SEND INFORMATION

Inside and outside the NEURON are fluids containing electrically charged atoms and molecules called ions. Positively charged sodium and

potassium ions Negatively charged chloride ions

Resting Potential-a NEURON has a stable, negative charge when the cell is inactive.

Action Potential-a shift in NEURON’S electrical charge that travels along an Axon.

NEURONS USE ENERGY TO SEND INFORMATION

Absolute Refractory Period-minimum length of time after an Action Potential during which another action potential cannot begin. Not a very long period of time-milliseconds

All or None Law Neural Impulse is all or none-like firing a gun-

NEURONS firing of Action Potential-all the same size-weaker stimuli do not produce weaker Action Potentials.

NEURONS can convey strength of stimulus by the rate at which they fire Action Potentials

Where Neurons meet-The Synapse

NEURONS don’t touch-they are separated by the Synaptic Cleft Synaptic Cleft-a microscopic gap between

the terminal button of one NEURON and the cell membrane of another NEURON Signals have to jump the gap to communicate

Sending NEURON-Presynaptic NEURON Receiving NEURON-Postsynaptic NEURON

NEUROtransmitters-chemicals that transmit information from one NEURON to another. Chemicals are stored in Synaptic Vesicles

Where Neurons meet-The Synapse

Receiving Signals: Postsynaptic Potentials When a NEUROtransmitter meets a

receptor molecule reactions cause Postsynaptic Potential (PSP) PSP-a voltage change at a receptor site on

a postsynaptic cell membrane Not All Or None Law-varies in size and

probability of NEURAL impulse Two Types of Messages sent from cell

to cell Excitatory and Inhibitory

Where Neurons meet-The Synapse

Two Types of Messages Cell to Cell Excitatory PSP-positive voltage shift that

increases the likelihood that the postsynaptic NEURON will fire Action Potentials.

Inhibitory PSP-negative voltage shift that decreases the likelihood that the postsynaptic NEURON will fire Action Potentials.

NEUROtransmitters drift away from receptor sites-most are reabsorbed-REUPTAKE-a process by which NEUROtransmitters are sponged up from the synaptic cleft by the presynaptic membrane

How NEUROtransmitters effect Behavior

NEUROtransmitters are fundamental to behavior:

Muscle movements Moods, Mental Health

15 to 20 chemical substances qualify as NEUROtransmitters Specific NEUROtransmitters work at

specific kinds of Synapses. Transmitters must fit into into receptor site

How NEUROtransmitters effect Behavior

Common and Specific NEUROtransmitters Acetylcholine (ACh)-motor NEURONS and

voluntary muscles-every move you make—typing, walking, talking, breathing—regulates attention, arousal, and memory Agonist-chemical that mimics the action of a

NEUROtransmitter (ACh and Nicotine) Antagonist-chemical that opposes the action of

a NEUROtransmitter Monoamines: Dopamine, Norepinephrine, and

Seratonin

How NEUROtransmitters effect Behavior

Common and Specific NEUROtransmitters Dopamine (DA)-controls voluntary movement,

pleasurable emotions—Cocaine and amphetamines elevate activity at DA synapses

Norepinephrine (NE)-modulation of mood and arousal—Cocaine and amphetamines elevate activity at NE synapses

Seratonin-regulates sleep and wakefulness, eating, aggression—abnormal levels lead to depression and obsessive compulsive disorder (Prozac affect Seratonin circuits)

Endorphins-refers to the entire family of internally produced chemicals that resemble opiates in structure and effects

Organization of Nervous System

85 to 180 Billion NEURONS in the Brain Peripheral Nervous System-all nerves outside

of brain and spinal cord Nerves are bundles of NEURON fibers (Axons) that are

routed together in the peripheral nervous system Somatic Nervous System-nerves that connect to

voluntary skeletal muscles and to sensory receptors Receptors in skin, muscles, and joints to the Central

Nervous System(CNS) 2 kinds of nerve systems:

Afferent nerve fibers-carry information inward to CNS Efferent nerve fibers-carry information outward to body

Organization of Nervous System

Autonomic Nervous System (ANS) is made up of nerves that connect to heart, blood vessels, smooth muscles, and glands. Autonomous system-involuntary—heart rate,

digestion and perspiration ANS is divided into 2 branches:

parasympathetic and sympathetic Parasympathetic: conserves bodily resources-

promote digestion, slow heart rate, reduce blood pressure, bladder contracted

Sympathetic: mobilizes the body’s resources for emergencies-dilated pupils, increased respiration

Organization of Nervous System

Central Nervous System (CNS)-portion of nervous system that lies within the skull and spinal column-brain and spinal cord Protected by sheaths called meninges and is

bathed in a special nutritive fluid called-Cerebrospinal fluid (CSF)-nourishes and protects the brain

CSF is carefully filtered, to enter substances have to go through Blood Brain Barrier-a semipermeable membrane-like mechanism that stops some chemicals from passing between bloodstream and brain

Organization of Nervous System

Parts of the Central Nervous System The Spinal Cord-connects the brain to the rest of

the body through the peripheral nervous system. Extension of the brain Houses bundles of Axons that carry the brain’s

commands to peripheral nerves and that relay sensations from the periphery of the body to the brain

The Brain-weighs only 3lbs. Contains billions of cells that integrate information from inside and outside the body, coordinate the body’s actions and enable humans to talk, think, remember, plan, create, and dream.

The Brain and Behavior

Hindbrain-includes the cerebellum and two structures found in the lower part of the brainstem: the medulla and the pons. Medulla attaches to the spinal cord-in charge of

vital functions like circulation, breathing, maintaining muscle tone, regulating reflexes

The pons a bridge of fibers that connects the brainstem with the cerebellum-several clusters of cell bodies involved with sleep and arousal

The cerebellum-located adjacent to the back surface of brainstem. Controls balance and movement.

The Brain and Behavior

Midbrain-segment of brain that lies between the hindbrain and the forebrain. Concerned with certain sensory

processes such as locating where things are in space

The Brain and Behavior Forebrain-largest and most complex region of the

brain-includes thalamus, hypothalamus, limbic system, and cerebrum Thalamus-structure which all sensory information

except smell must pass through Hypothalamus-structure that is involved in regulation of

basic biological needs-link between brain and endocrine system

Limbic System-structures loosely organized and include parts of the thalamus, hypothalamus, hippocampus, amygdala, and septum—regulates emotion, memory and motivation.

The Cerebrum-largest and most complex part of the human brain-responsible for thinking, remembering, learning, and consciousness. The Cerebrum is divided into left and right hemispheres-Corpus Callosum connects two hemispheres

The Brain and Behavior

Each Cerebral Hemisphere is divided into four parts called Lobes. Occipital Lobe-back of head, visual signs

and visual processing-called primary visual cortex

Parietal Lobe-forward of the Occipital Lobe, sense of touch-called primary somatosensory cortex

Temporal Lobe-(near the temples), auditory processing-called primary auditory cortex

Frontal Lobe-largest lobe in brain, controls muscles-called primary motor cortex, motor skills

Looking inside the Brain-Research Methods Electrical Recordings-machine that records

broad patterns of brain electrical activity—the electroencephalograph (EEG)-brain waves.

Lesioning-involves destroying a specific piece of the brain-animals

Electrical Stimulation (ESB)-involves sending a weak electric current into brain structure to stimulate (activate) it. Delivered through an electrode.

Brain Imaging Procedures-CT Scan, PET Scan, MRI

Right Hemisphere vs. Left Hemisphere

Left Hemisphere has historically been associated with language/language processing

Split Brain Surgery-Corpus Callosum (which connects hemispheres) is cut to reduce epileptic seizures

Each Hemisphere’s primary connections are to the opposite side of the body-left to right, right to left

Specialization in the Hemispheres

How to study the separate Hemispheres: Perceptual Asymetrics:looks at left-right

imbalances between cerebral hemispheres in the speed of visual or auditory processing

The left hemisphere usually is better on tasks involving verbal processing, such as language speech reading and writing

The right hemisphere exhibits superiority on many tasks involving non-verbal processing such as most spatial musical and visual recognition tasks

The Endocrine System-Another way to communicate Second communication to the nervous

system is the Endocrine system. Consists of glands that secrete chemicals into

the bloodstream that help control bodily functioning.

The messengers within the Endocrine system are HORMONES-chemical substances released by the Endocrine glands. Hormonal transmitters diffuse through the

bloodstream Some hormones are released in response to

changing conditions in the body

The Endocrine System-Another way to communicate Examples of Hormones:

Hormones released by the stomach and intestines control digestion

Kidney hormones regulate blood pressure Pancreatic hormones (insulin)essential for cells to

use sugar from the blood. Much of the Endocrine system is controlled by

the nervous system through the hypothalamus-connected to the pituitary gland-releases a great variety of hormones that fan out around the body stimulating actions in other endocrine glands.

The Endocrine Glands

Pituitary-master gland that produces hormones that influence thyroid, pancreas, gonads, adrenals

Thyroid-regulate metabolic rate Adrenal-control salt and carbohydrate

metabolism, secrete hormones that activate arousal and sleep

Pancreas-produces insulin and glucogen(sugar) Gonads-Ovaries (females) Testes (males)

involved in secondary sex characteristics and reproduction

Heredity and Behavior

Behavioral Genetics: an interdisciplinary field that studies the influence of genetic factors on behavioral traits

Every cell in your body contains messages from your mother and father-messages found on chromosomes

Chromosomes strands of DNA that carry genetic information

Genes are DNA segments that serve as the key functional unit of hereditary transmission

Heredity and Behavior

Genotype-refers to a person’s genetic makeup Phenotype-refers to the ways in which a person’s

genotype is manifested in observable characteristics Polygenic traits-characteristics that are influenced by

more than one pair of genes Family Studies-researchers asses hereditary

influence by examining blood relatives to see how much they resemble one another on a specific trait

Twin studies-researchers assess hereditary influence by comparing the resemblance of identical twins and fraternal twins with respect to a trait

Heredity and Behavior

Adoption studies-asses hereditary influence by examining the resemblance between adopted children and both their biological and adoptive parents

Genetic mapping-process of determining the location and chemical sequence of specific genes on specific chromosomes.

Hereditary and Environment Evolutionary psychology

Darwin-Natural Selection Fitness-reproductive success of an organism relative

to the average reproductive success in the population

Characteristics of survival or reproduction are more likely “selected” over time

Mutations occur as a result of Genetic Drift-and are changes in pieces of DNA

Adaptations-inherited characteristic that occurs in large numbers of population because it helped solve a problem of survival or reproduction Behaviors can be adaptive traits