The Biological Basis of Behavior Chapter 2 Psychology

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

Vocabulary Chapter 2 l l l l l Neurons Dendrites Synapse Neurotransmitters Receptor site Cerebellum Thalamus Hypothalamus Cerebral cortex l l l l Occipital Lobe Temporal Lobe Frontal Lobe Corpus Callosum Spinal cord Adrenal glands Genes 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 l Neurons have many of the same features as other cells l Nucleus l Cytoplasm l Cell membrane l l What makes neurons unique is their shape and function Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

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

Glial Cells that insulate and support neurons l Create the myelin sheath l Remove waste products l Provide nourishment l Prevent harmful substances from entering the brain l 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 l Ions l l Charged molecules Resting Potential l When more negative ions are inside the neuron than outside Charge is approximately -70 m. V Neuron is not transmitting information Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

The Neural Impulse l Polarization l l When the electrical charge of a cell moves away from zero Depolarization l 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 l Action Potential l 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 l Graded Potentials Subthreshold depolarization l Many subthreshold depolarizations are added together to produce an action potential (a process known as summation) l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

The Neural Impulse l Absolute refractory period l l Period immediately after an action potential when another action potential cannot occur Relative refractory period l 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 l Synaptic space (synaptic cleft) l l Terminal button l l Tiny gap between neurons Enlarged area at the end of an axon The synapse l 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 l Synaptic vesicles l l Neurotransmitters l l Sacs in terminal button that release chemicals into synaptic space Chemicals released by synaptic vesicles Receptor sites l Location on receptor neuron for specific neurotransmitter Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

Some Well-Known Neurotransmitters l Acetylcholine (ACh) l l 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 l l l 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 l Serotonin Found throughout the brain l Appears to sets an “emotional tone” l Low serotonin levels are implicated in depression l l Endorphins l 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 l Botulism l Blocks release of ACh at the neuromuscular junction, causing paralysis l “Botox” is botulism toxin used to prevent facial muscles from making wrinkles l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

Psychopharmacology l Curare l l l Antipsychotic medications l l l Can stun or kill prey quickly Blocks ACh receptors causing paralysis Block dopamine receptors Reduces schizophrenic hallucinations Caffeine l 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 l Cocaine Prevents reabsorption of dopamine l Leads to heightened arousal of entire nervous system l 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 l Rat studies show that an “enriched” environment leads to larger neurons with more connections l Has also been shown in humans l Recent research has uncovered evidence of neurogenesis, or the production of new brain cells, in human brains l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

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

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

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

The Brain – The Limbic System l l Ring of structures located between the central core and the cerebral hemispheres Important to learning and emotional behavior l l 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 l Occipital lobe l l Receives and processes visual information Temporal lobe l l 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 l Parietal lobe l l l Receives sensory information from body Involved in spatial abilities Frontal lobe l l 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 l Corpus Callosum l l l 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 l Much information about functions of each hemisphere has come from studying splitbrain 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 l Used to study activity of a single neuron l 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 l An example is an EEG, which uses electrodes placed on a person’s scalp to measure brain activity l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

Functional Imaging l EEG imaging l l 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) l Can localize activity more precisely than EEG Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

Functional Imaging l Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) l l Use radioactive glucose to determine location of greatest brain activity Functional Magnetic Resonance Imaging (f. MRI) l 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 l Carries motor impulses from the brain to internal organs and muscles l Carries sensory information from extremities and internal organs to the brain l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

The Somatic Nervous System Consists of neurons that communicate between the body and the brain l Afferent neurons l l l Neurons that carry messages from sense organs to spinal cord Efferent neurons l 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 l Sympathetic division l l 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 l Parasympathetic division l l 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 l Endocrine glands secrete hormones into the bloodstream l Hormones serve to organize the nervous system and body l Hormones also activate behavior, such as sexual behavior l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

The Endocrine System l Thyroid gland l l Secretes hormones (primarily thyroxin) that control metabolism Parathyroid glands l 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 l Pineal gland l l Secretes melatonin which regulates the sleep-wake cycle Pancreas l l Regulates blood-sugar levels Secretes insulin and glucagon Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

The Endocrine System l Pituitary gland l l Gonads l l Referred to as the “master gland” because it regulates many other glands Ovaries and testes secrete estrogens androgens Adrenal glands l Secretes hormones in Psychology: An Introduction reaction to stress. 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 l Chromosomes l l l Pairs of thread like bodies that contain genes Deoxyribonucleic acid (DNA) Organic molecule arranged in a double-helix l Contains the “code of life” l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall

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

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

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

Evolutionary Psychology l Natural selection l l “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 l Could also be used to create new categories of people, such as people bred to be good soldiers or manual laborers l Psychology: An Introduction Charles A. Morris & Albert A. Maisto © 2005 Prentice Hall