Chapter 3: The Biology of Behavior Key Terms Flashcards
DNA (deoxyribonucleic acid):
A large molecule that contains genes.
Chromosome:
A coiled-up thread of DNA; 23 pairs of chromosomes in every cell of your body
Genome:
All the genetic information in DNA.
Genotype:
The entire genetic makeup of an organism.
Phenotype:
An organism’s observed characteristics (gene expression)
Genes:
Small segments of DNA that contain information for producing proteins.
They have a profound level of control shaping how you think and feel.
Polygenic:
The process by which many genes interact to create a single characteristic.
All psychological and almost all physical traits in humans are polygenic.
Monogenic:
The hereditary passing on of traits determined by a single gene.
Humans have very few traits that result from a single gene.
Mutation:
A random change in genetic sequence.
Alleles:
Different forms of a gene.
Example: There are two forms of the gene that is responsible for lactose tolerance/intolerance; one allele causes lactose intolerance, while another allele does not.
Dominant alleles:
Alleles that show their effect even if there is only one allele for that trait in the pair.
Punnett square = One capital letter (Tt) or two capital letters (TT)
Recessive alleles:
Alleles that show their effects only when both alleles are the same.
Punnett square: Two lowercase letters (tt)
Behavioral genetics:
The scientific study of the role of heredity in behavior.
- The relationship between specific genes and behavior is complex, usually with many genes involved in each trait
- Studying twins and adoptees as well as genetic markers = breaks down influences of hereditary (nature) and environmental (nurture) on behavior.
- The ENVIRONMENT influences how and when genes affect behavior.
Heritability:
The extent to which a characteristic is influenced by genetics.
Epigenetics:
The study of changes in the way genes are turned on or off without a change in the sequence of DNA.
Involves heritable changes to DNA that are independent of the genetic sequence (ENVIRONMENT) yet influence its expression = NURTURE shapes NATURE
Central nervous system (CNS):
The part of the nervous system that comprises the brain and spinal cord.
Peripheral nervous system:
The part of the nervous system that comprises all the nerve cells in the body outside the central nervous system.
Somatic nervous system:
Nerve cells of the peripheral nervous system that serve the skeletal muscles.
Somatic nerves transmit from the central nervous system (CNS) to the skeletal muscles and sensory information from the skeletal muscles back to the CNS.
Automatic nervous system (ANS):
All the nerves of the peripheral nervous system that serve involuntary systems of the body, such as the internal organs and glands.
Sympathetic nervous system:
The branch of the autonomic nervous system that activates bodily systems in times of emergency.
Parasympathetic nervous system:
The branch of the autonomic nervous system that usually relaxes or returns the body to a less active, restful state.
Glial cells:
The central nervous system is made up of two types of cells: glial cells and neurons.
Glial cells provide structural support for the CNS, promote efficient communication between neurons, and remove cellular debris.
Neurons:
The cells that process and transmit information in the nervous system.
THREE MAJOR PRINCIPLES CONCERNING NEURAL COMMUNICATION:
- Neurons are the building blocks of the nervous system. All the major structures of the brain are composed of neurons.
- Information travels within a neuron in the form of an electrical signal transmitted by action potentials.
- Information is transmitted between neurons by means of neurotransmitters.
Neurotransmitters:
Chemicals that transmit information between neurons.
Soma:
The cell body of the neuron.
Axon:
A long projection that extends from a neuron’s soma.
It transmits electrical impulses toward the adjacent neuron and stimulates the release of neurotransmitters.
Dendrites:
Fingerlike projections from a neuron’s soma that receive incoming messages from other neurons.
Myelin sheath:
The fatty substance wrapped around some axons, which insulates the axon, making the nerve impulse travel more efficiently.
Synapse:
The junction between an axon and the adjacent neuron, where information is transmitted from one neuron to another.
Terminal button:
A little knob at the end of the axon that contains many sacs of neurotransmitters.
Sensory neurons:
One of three types of neurons: sensory neurons, motor neurons, and interneurons
Nerve cells that receive incoming sensory information from the sense organs (eye, ear, skin, tongue, nose).
Motor neurons:
One of three types of neurons: sensory neurons, motor neurons, and interneurons
Nerve cells that carry commands for movement from the brain to the muscles of the body.
Mirror neurons:
Type of motor neuron; are active when we observe others performing an action as well as when we are performing the same action.
Interneurons:
One of three types of neurons: sensory neurons, motor neurons, and interneurons
Neurons that communicate only with other neurons; the most common kind of neuron in the brain.
Action potential:
Neural communication is a two-step process: action potential and neurotransmission.
The impulse of positive charge that runs down an axon.
Ions:
Chemically charged particles that predominate in bodily fluids; found both inside and outside cells.
Resting potential:
The difference in the electrical charge between the inside and outside of the axon when the neuron is at rest.
Refractory period:
The span of time, after an action potential has been generated, when the neuron is returning to its resting state and the neuron cannot generate an action potential.
Nodes of Ranvier:
The gap(s) in the myelin sheath across which the action potential jumps.
The myelin sheath isn’t a smooth tube. It’s more like many tubes bunched together.
All-or-none principle:
The idea that, once the threshold has been crossed, either an action potential fires or it does not.
Synaptic vesicles:
Tiny sacs in the terminal buttons that contain neurotransmitters.
Graded potentials:
Small changes in membrane potential that by themselves are insufficient to trigger an action potential.
Acetylcholine (ACh):
A neurotransmitter that controls muscle movement and plays a role in mental processes such as learning, memory, attention, sleeping, and dreaming.
Dopamine:
A neurotransmitter released in response to behaviors that feel good or are rewarding to the person or animal; also involved in voluntary motor control.
Epinephrine:
Also known as adrenaline, a neurotransmitter that arouses bodily systems (such as increasing heart rate).
Epinephrine tends not to affect mental states, whereas norepinephrine increases mental arousal and alertness.
Norepinephrine:
A neurotransmitter that activates the sympathetic response to stress, increasing heart rate, rate of respiration, and blood pressure in support of rapid action.
Increases mental arousal and alertness, unlike epinephrine.
Serotonin:
A neurotransmitter with wide-ranging effects; involved in dreaming and in controlling emotional states, especially anger, anxiety, and depression.
GABA (gamma-aminobutyric acid):
A major inhibitory neurotransmitter in the brain that tells postsynaptic neurons NOT to fire; it slows CNS activity and is necessary to regulate and control neural activity.
Serves as “brakes” for CNS. Otherwise, it could run out of control.
Glutamate:
A major excitatory neurotransmitter in the brain that increases the likelihood that a postsynaptic neuron will fire; important in learning, memory, neural processing, and brain development.
Amplifies some neural transmissions so that a person can tell the difference between important and less important information.
Neuropeptides:
Small strings of amino acids that carry information among neurons but are not considered to be neurotransmitters formally because of their size, origin, and mechanisms of action.
Oxytocin, neurotensin, and substance P.
Medulla:
A HINDBRAIN structure that extends directly from the spinal cord; regulates breathing, heart rate, and blood pressure, as well as REFLEXES
Reflexes:
Inborn and involuntary behaviors—such as coughing, swallowing, sneezing, or vomiting—that are elicited by very specific stimuli.
Pons:
A HINDBRAIN structure that serves as a bridge between lower brain regions and higher midbrain and forebrain activity.
Serves many of the same automatic functions as the medulla as well as body movement, including facial expressions.
Cerebellum:
A HINDBRAIN structure involved in body movement, balance, coordination, fine-tuning motor skills, and cognitive activities such as learning and language.
VERY IMPORTANT; 80% of all brain neurons are in the cerebellum
Reticular formation:
A network of nerve fibers that runs up through both the HINDBRAIN and the MIDBRAIN; it is crucial to wakefulness
Thalamus:
A FOREBRAIN structure that receives information from the SENSES (eyes, ears, skin, taste buds) and relays it to the cerebral cortex for processing.
NOT REALLY SMELL (olfaction has different, more powerful processing connections, even though it has a thalamic relay)
Limbic system:
A connection group of FOREBRAIN structures (HYPOTHALAMUS, AMYGDALA, HIPPOCAMPUS, and CINGULATE CORTEX)
Shares important functions in emotion memory and motivation and regulate autonomic and endocrine function.
Hypothalamus:
A LIMBIC structure; the master regulator of almost all major drives and motives we have, such as hunger, thirst, temperature, and sexual behavior; also controls the pituitary gland.
Hippocampus:
A LIMBIC structure that wraps itself around the thalamus; plays a vital role in LEARNING AND MEMORY.
Sensory information goes to the hippocampus.
Amygdala:
A small, almond-shaped structure located directly in front of the hippocampus; has connections with many important brain regions and is important for processing EMOITIONAL INFORMATION, especially that related to fear.
Cingulate gyrus:
A belt-like structure in the middle of the brain; plays an important role in ATTENTION AND COGNITIVE CONTROL
Basal ganglia:
A collection of structures surrounding the thalamus; involved in VOLUNTARY MOTOR CONTROL
Cerebrum:
Each of the larger halves of the brain; covered with convolutions, or folds.
Composed of lobes, which are also bilateral
Cerebral cortex:
The thin outer layer of the cerebrum, in which much of HUMAN THOUGHT, PLANNING, PERCEPTION, AND CONSCIOUSNESS takes place.
It is the site of ALL BRAIN ACTIVITY THAT MAKES US MOST HUMAN
Somatosensory cortex:
A strip of the parietal lobe involved in the processing and perception of sensory information from the body, especially TEMPERATURE, TOUCH, PRESSURE, AND PAIN.
Insula:
A small structure inside the CEREBRUM that plays an important role in the perception of BODILY SENSATIONS, EMOTIONAL STATES, EMPATHY, AND ADDICTIVE BEHAVIOR.
Corpus callosum:
Nerve fibers that connect the two hemispheres of the brain; provides channel for extensive communication between the hemispheres in both logical and creative tasks.
Aphasia:
A deficit in the ability to speak or comprehend language.
Broca’s area:
The area in the left frontal lobe responsible for the ability to produce speech.
Wernicke’s area:
The area deep in the left temporal lobe responsible for the ability to speak in meaningful sentences and to comprehend the meaning of speech.
Neuroplasticity:
The brain’s ability to adopt new functions, reorganize itself, or make new neural connections throughout life, as a function of experience.
Varies (decreases) with age.
Neurogenesis:
The development of new neurons; experience-based change
Arborization:
The growth and formation of new dendrites; experience-based change
Synaptogenesis:
The formation of entirely new synapses or connections with other neurons; experience-based change; THE BASIS OF LEARNING
Electroencephalography (EEG):
A method for measuring brain activity in which the electrical activity of the brain is recorded from electrodes placed on a person’s scalp.
Shows WHEN brain activity occurs, but does not precisely indicate WHERE
Event-related potential (ERP):
A technique that extracts electrical activity from raw EEG data to measure cognitive processes.
Magnetic resonance imaging (MRI):
A brain imaging technique that uses magnetic fields to produce detailed images of the structure of the brain and other soft tissues.
Very useful for looking at structures of the brain, but does not tell us anything about ACTIVITY
Functional MRI (fMRI):
A brain imaging technique that uses magnetic fields to produce detailed images of activity in areas of the brain and other soft tissues.
Tells us WHERE brain activity occurs, but does not tell us WHEN.
Positron emission tomography (PET):
A brain imaging technique that measures blood flow to active areas in the brain.
Much more risky than fMRI, but it measures the same thing.
Endocrine system:
The system of glands that secrete and regulate hormones in the body.
Hormones:
Chemicals, secreted by glands, that travel in the bloodstream and carry messages to tissues and organs all over the body.
Pituitary gland:
The master endocrine gland of the body; controls the release of hormones from glands throughout the body.
Adrenal glands:
Endocrine structures that release hormones important in regulating the stress response and emotions.
Catecholamines:
Chemicals released from the adrenal glands that function as hormones and as neurotransmitters to control ANS activation.
They are involved in the “fight or flight” response. Major catecholamines include dopamine and norepinephrine.
Cortisol:
The major glucocorticoid produced in humans, also commonly known as the “stress hormone.” It regulates many important metabolic functions.
