Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Biological Basis of Behavior Chapter 2

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Neurons: The Messengers About 100 billion neurons (nerve cells) in the human brain Neurons have many of the same features as other cells Nucleus Cytoplasm Cell membrane What makes neurons unique is their shape and function

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Structure of Neurons Dendrites Carry information to the cell body from other neurons Cell Body (Soma) Contains nucleus Axon Carries information to the next cell Myelin Sheath Insulates the axon and speeds up the neural impulse

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Types of Neurons Sensory neurons Carry information from sensory systems to the brain Also referred to as afferent Motor neurons Carry information from the brain to muscles and glands Also referred to as efferent Interneurons Carry information between other neurons

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Glial Cells Cells that insulate and support neurons Create the myelin sheath Remove waste products Provide nourishment Prevent harmful substances from entering the brain

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse Ions Charged molecules Resting Potential When more negative ions are inside the neuron than outside Charge is approximately -70mV Neuron is not transmitting information

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse Polarization When the electrical charge of a cell moves away from zero Depolarization When the electrical charge of a cell moves toward zero

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse Action Potential Sudden, massive change in charge in the neuron Occurs when depolarization reaches the threshold of excitation Ions flow across cell membrane

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse Graded Potentials Subthreshold depolarization Many subthreshold depolarizations are added together to produce an action potential (a process known as summation)

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse All-or-None Law A neuron either fires or it does not When it does fire, it will always produce an impulse of the same strength Intensity of a stimulus is coded by the frequency of action potentials

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Neural Impulse Absolute refractory period Period immediately after an action potential when another action potential cannot occur Relative refractory period Period following absolute refractory period when a neuron will only respond to a stronger than normal impulse

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Synapse Synaptic space (synaptic cleft) Tiny gap between neurons Terminal button Enlarged area at the end of an axon The synapse Composed of the terminal button of one neuron, the synaptic space, and the dendrites or cell body of the receiving neuron

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Transmission Between Neurons Synaptic vesicles Sacs in terminal button that release chemicals into synaptic space Neurotransmitters Chemicals released by synaptic vesicles Receptor sites Location on receptor neuron for specific neurotransmitter

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Some Well-Known Neurotransmitters Acetylcholine (ACh) Released at the neuromuscular junction Plays an important role in arousal and attention Loss of ACh producing cells is linked to Alzheimer’s Disease Dopamine Affects neurons associated with voluntary movement Plays a role in learning, memory, and emotions Loss of dopamine-producing cells causes symptoms of Parkinson’s Disease

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Some Well-Known Neurotransmitters Serotonin Found throughout the brain Appears to sets an “emotional tone” Low serotonin levels are implicated in depression Endorphins Reduce pain by inhibiting or “turning down” neurons that transmit pain information

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Psychopharmacology Most psychoactive drugs (and toxins) work by blocking or enhancing synaptic transmission Botulism Blocks release of ACh at the neuromuscular junction, causing paralysis “Botox” is botulism toxin used to prevent facial muscles from making wrinkles

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Psychopharmacology Curare Can stun or kill prey quickly Blocks ACh receptors causing paralysis Antipsychotic medications Block dopamine receptors Reduces schizophrenic hallucinations Caffeine Increases the release of excitatory neurotransmitters by blocking the inhibitory neurotransmitter adenosine

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Psychopharmacology Cocaine Prevents reabsorption of dopamine Leads to heightened arousal of entire nervous system

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Neural Plasticity The brain can be changed, both structurally and chemically, by experience Rat studies show that an “enriched” environment leads to larger neurons with more connections Has also been shown in humans Recent research has uncovered evidence of neurogenesis, or the production of new brain cells, in human brains

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Nervous System Organization Central nervous system (CNS) Consists of the brain and spinal cord Peripheral nervous system Connects the CNS to the rest of the body Somatic nervous system Autonomic nervous system

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Central Nervous System BrainSpinal Cord

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Brain – The Central Core Medulla Controls breathing, heart rate, and blood pressure Pons Maintains the sleep- wake cycle Cerebellum Coordinates body’s movements

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Brain – The Central Core Thalamus Relays information from sensory receptors to the brain Hypothalamus Influences motivated behavior Regulates hunger, thirst, body temperature, and sexual drive. Directly involved in emotional behavior

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Brain – The Central Core Reticular formation Network of neurons found throughout the brain Serves to alert and arouse higher brain in response to incoming information

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Brain – The Limbic System Ring of structures located between the central core and the cerebral hemispheres Important to learning and emotional behavior Hippocampus essential in formation of new memories Amygdala, together with the hippocampus, is important for regulating emotions

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Cerebral Cortex Occipital lobe Receives and processes visual information Temporal lobe Complex visual tasks such as face recognition Receives and processed auditory information Involved in balance, some emotions and motivations Some language processing

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Cerebral Cortex Parietal lobe Receives sensory information from body Involved in spatial abilities Frontal lobe Coordinated information from other lobes Controls voluntary movement, attention, setting goals, and expression of appropriate emotions

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Hemispheric Specialization Corpus Callosum Fibers that connect the two hemispheres Allow close communication between left and right hemishphere Each hemisphere appears to specialize in certain functions

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Split-Brain Research Much information about functions of each hemisphere has come from studying split- brain patients

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Tools for Studying the Nervous System

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Microelectrode Techniques Very small electrodes inserted into individual neurons Used to study activity of a single neuron

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Macroelectrode Techniques Used to get a picture of overall activity in the brain An example is an EEG, which uses electrodes placed on a person’s scalp to measure brain activity

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Structural Imaging Computerized Axial Tomography (CT- scan) Uses X-rays to create a 3-dimensional image of the brain Magnetic Resonance Imaging (MRI) Uses a magnetic field and radio waves to produce images

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Functional Imaging EEG imaging electrical activity on the scalp from millions of neurons is used to produce a continuous picture of activity in the brain Magentoencephalography (MEG) and Magnetic source imaging (MSI) Can localize activity more precisely than EEG

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Functional Imaging Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) Use radioactive glucose to determine location of greatest brain activity Functional Magnetic Resonance Imaging (fMRI) Shows function and structure by measuring movement of blood molecules within the brain

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Spinal Cord

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Spinal Cord Complex cable of nerves that connects brain to rest of the body Carries motor impulses from the brain to internal organs and muscles Carries sensory information from extremities and internal organs to the brain

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Spinal Cord The spinal cord controls some protective reflex movements without any input from the brain

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Peripheral Nervous System Peripheral Nervous System Somatic Nervous System Autonomic Nervous System Sympathetic Division Parasympathetic Division

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Somatic Nervous System Consists of neurons that communicate between the body and the brain Afferent neurons Neurons that carry messages from sense organs to spinal cord Efferent neurons Neurons that carry messages from the spinal cord or brain to muscles and glands

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Autonomic Nervous System Sympathetic division Most active when you are angry, afraid, or aroused Fight-or-flight response Increases heart rate and breathing Stops digestion

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Autonomic Nervous System Parasympathetic division Calms body Produces effects opposite to those of the sympathetic division Reduces heart rate and breathing Restores digestion

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Endocrine System

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Endocrine System Helps coordinate and integrate complex psychological reactions Endocrine glands secrete hormones into the bloodstream Hormones serve to organize the nervous system and body Hormones also activate behavior, such as sexual behavior

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Endocrine System Thyroid gland Secretes hormones (primarily thyroxin) that control metabolism Parathyroid glands Control levels of calcium and phosphate which in turn controls levels of excitability

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Endocrine System Pineal gland Secretes melatonin which regulates the sleep-wake cycle Pancreas Regulates blood-sugar levels Secretes insulin and glucagon

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall The Endocrine System Pituitary gland Referred to as the “master gland” because it regulates many other glands Gonads Ovaries and testes secrete estrogens and androgens Adrenal glands Secretes hormones in reaction to stress

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Genes, Evolution, and Behavior

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Genetics Heredity - transmission of trait from one generation to next Chromosomes Pairs of thread like bodies that contain genes Deoxyribonucleic acid (DNA) Organic molecule arranged in a double-helix Contains the “code of life”

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Behavior Genetics Study of behavior from a genetic perspective Animal behavior genetic studies include: Strain studies Selection studies

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Human Behavior Genetics Family studies Assume that close family members share more of a trait than non-relatives Used to assess the heritability of psychological disorders or traits Twin studies Used to determine how heritable a trait or disorder may be Identical twins would have highest heritability

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Human Behavior Genetics Adoption studies Used to assess the influence of environment Molecular genetics Direct study of the genetic code

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Evolutionary Psychology Natural selection “Survival of the fittest” Evolutionary psychology looks at the adaptive or survival value of behaviors

Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall Social Implications Study of biological origins of behavior could lead to genocide and eugenics aimed at eliminating certain types of people Could also be used to create new categories of people, such as people bred to be good soldiers or manual laborers