Biology and Behavior Flashcards

The EEG and the Microelectrode

• Electroencephalograph (EEG):

  • Invented by Austrian psychiatrist Hans Berger in 1924.

  • Records electrical activity in the brain.

  • Detects electrical activity in different brain areas but cannot reveal activity of individual neurons.

• Microelectrode:

  • A very small wire that can be inserted near or into a single neuron without causing damage.

Imaging Techniques

• CT Scan:

  • Computerized, cross-sectional images.

  • Reveals brain structures, abnormalities, and injuries, including tumors and evidence of old or recent strokes.

• MRI:

  • Produces clearer and more detailed images compared to CT scans.

  • Does not expose individuals to potentially dangerous X-rays.

  • Used to find abnormalities in the central nervous system and other body systems.

• PET Scan:

  • Maps patterns of blood flow, oxygen use, and glucose consumption.

  • Shows the action of drugs and other biochemical substances in the brain and other bodily organs.

• fMRI:

  • Does not require injections of radioactive or other material.

  • Identifies locations of activity more precisely than PET scans.

  • Detects changes in less than a second, while PET scans take about a minute.

• SQUID, MEG, and DTI:

  • Identify exact locations of brain lesions and malfunctions.

  • Provide greater precision and speed compared to older imaging techniques.

  • Used for conditions like epilepsy, strokes, Alzheimer’s disease, and multiple sclerosis.

Neurons and Neurotransmitters

• Neurons:

  • Specialized cells that conduct impulses through the nervous system, sending and receiving messages.

  • Humans are born with approximately 100 billion neurons.

• Neurotransmitters:

  • Specialized chemicals that facilitate or inhibit the transmission of messages between neurons.

Types of Neurons

• Sensory Neurons:

  • Carry incoming information.

  • Transmit information from the senses to the brain.

• Motor Neurons:

  • Carry outgoing information.

  • Transmit information from the brain to the muscles.

• Interneurons:

  • Located between sensory and motor neurons.

  • Help transfer information.

  • Most numerous type of neuron.

Structure of the Neuron

• Dendrites:

  • Short fibers extending from the cell body.

  • Receive messages from other neurons.

• Axon:

  • Long, tube-like structure extending from the cell body.

  • Carries the message.

• Cell Body (Soma):

  • Contains the nucleus.

  • Generates energy for the neuron to function.

• Myelin Sheath:

  • Fatty covering that insulates the axon.

  • Increases the speed of communication.

  • Damage causes loss of coordination, muscle relaxation, and visual/speech disturbance.

• Axon Terminal:

  • Where the axon ends.

  • Transmits information to dendrites, other cell bodies, and muscles.

• Vesicles:

  • Tiny sacs on the axon terminal.

  • Contain neurotransmitters.

• Neurotransmitter:

  • Chemical message.

• Node of Ranvier:

  • Gap in the myelin sheath.

  • Action potential is regenerated at each node.

• Presynaptic Neuron:

  • Sending neuron.

• Postsynaptic Neuron:

  • Receiving neuron.

• Synaptic Cleft:

  • Tiny gap between neurons.

Additional Neuron Components

• Glial cells

  • Means "glue."

  • Hold neurons together for communication.

  • Bring nutrition to neurons.

  • Take away waste.

  • Outnumber neurons by 10 to 1.

• Ions

  • Potassium (K^-) is inside the axon.

  • Sodium (Na^+) is on the outside of the axon.

Action Potential

• Electrical impulse.

• Involves receiving and sending a message.

• Goes from -70mV to +30mV.

• Potassium and sodium switch places.

• -70 mV is resting potential, meaning no message is being sent.

• +30 mV indicates that a message has been received.

All or None Law

• A neuron either fires completely or not at all.

• Refractory Period:

  • Immediately after firing, a neuron enters a refractory period.

  • During this period, it cannot fire again for 1 to 2 milliseconds.

• Reuptake:

  • Neurotransmitters that do not attach to the receptor site are reabsorbed.

Strong vs. Weak Stimulus

• Neurological distinction depends on:

  • Number of neurons firing at the same time.

  • Rate of firing.

• Weak Stimulus:

  • May cause relatively few neurons to fire.

  • Neurons fire slowly.

• Strong Stimulus:

  • May trigger thousands of neurons to fire at the same time.

  • Neurons fire hundreds of times per second.

Neurotransmitters

• Chemicals that transmit signals across a synapse.

• Released from synaptic vesicles in the axon terminal of the sending neuron.

• Diffuse across the synaptic cleft and bind to receptor sites on the receiving neuron.

• Excess neurotransmitters are either broken down by enzymes or reabsorbed by the sending neuron (reuptake).

Specific Neurotransmitters and Their Functions

• Acetylcholine:

  • First neurotransmitter discovered.

  • Involved in attention, arousal, memory, and muscle movement.

  • Linked to Alzheimer’s disease.

• Serotonin:

  • Stabilizes mood.

  • Contributes to feelings of wellbeing and happiness.

  • Helps with sleeping, eating, and digestion.

• Norepinephrine:

  • Released when the brain perceives a stressful event.

  • Involved in the "fight or flight" response.

• Endorphins:

  • Natural pain relievers.

  • Released in response to stress.

• Dopamine:

  • Involved in muscle movement, pleasure centers, and attention.

  • Too little is linked to Parkinson’s disease.

  • Too much is linked to Schizophrenia.

  • Linked to ADHD.

• GABA:

  • Low levels are linked to anxiety, epilepsy, and chronic pain.

• Glutamate:

  • Involved in learning and memory.

  • Linked to schizophrenia.

Divisions of the Nervous System

• Nervous System

  • Central Nervous System (CNS)

    • Brain and spinal cord.

  • Peripheral Nervous System (PNS)

    • All the nerves that connect the central nervous system to the rest of the body

    • Somatic Nervous System (Voluntary)

      • Relays information to and from skin and skeletal muscles.

      • Consists of sensory nerves and motor nerves; makes is possible for us to sense our environment

    • Autonomic Nervous System (Involuntary)

      • Relays information to internal organs.

      • Transmits messages between the central nervous system and the glands and muscles

      • Sympathetic Nervous System

        • Controls organs in times of stress.

        • Prepares the body for action

      • Parasympathetic Nervous System

        • Controls organs when body is at rest.

        • Brings the body back to normal

The Central Nervous System

• Includes the spinal cord and the brain.

• Spinal Cord:

  • Links the body with the brain.

  • Transmits messages between the brain and nerves in other parts of the body.

  • Can act independently of the brain to protect the body from injury.

• Major Divisions of the Brain:

  • Hindbrain

  • Midbrain

  • Forebrain

The Brain

• Hindbrain:

  • Structures control heart rate, respiration, blood pressure, and other vital functions.

  • Brain Stem:

    • Handles critical functions for physical survival.

    • Damage can be life threatening.

    • Medulla:

      • Controls heartbeat, breathing, blood pressure, coughing, and swallowing.

    • Pons:

      • Plays a role in body movement.

      • Influences sleep and dreaming.

    • Reticular Formation:

      • Plays a crucial role in arousal and attention.

  • Cerebellum:

    • Critically important for the body’s ability to execute smooth, skilled movements.

• Midbrain:

  • Structures act primarily as relay stations.

  • Substantia Nigra:

    • Controls our unconscious motor actions.

• Forebrain:

  • Largest part of the brain.

  • Controls cognitive and motor functions.

  • Thalamus:

    • Relay station for information flowing into and out of the forebrain.

    • Regulates sleep cycles.

    • Damage can result in a vegetative state.

  • Hypothalamus:

    • Regulates hunger, thirst, sexual behavior, and emotional behaviors.

    • Regulates internal body temperature and circadian rhythm.

  • Limbic System:

    • Involved in emotional expression, memory, and motivation.

    • Amygdala:

      • Plays an important role in emotion, especially fear.

    • Hippocampus:

      • Involved in memories; damage stops the formation of new memories.

  • Cerebral Cortex:

    • The thinking part of the brain.

• Components of the Cerebrum:

  • Two hemispheres physically connected by the corpus callosum.

  • Contralateral Control:

    • The right cerebral hemisphere controls movement and feeling on the left side of the body.

    • The left hemisphere controls the right side of the body.

  • Cerebral Cortex:

    • Responsible for the higher mental processes of language, memory, and thinking.

• Cerebral Hemispheres:

  • Left Hemisphere:

    • Handles math, logic, analytical thought, and most language functions.

    • Coordinates complex movements

  • Right Hemisphere:

    • More adept at visual-spatial relations.

    • Better able to process music.

• Split Brain:

  • Split-brain operation involves surgery that splits the corpus callosum.

  • Decreases the frequency of seizures in people with severe epilepsy.

The Four Cerebral Lobes

• Frontal Lobes:

  • Largest lobe.

  • Prefrontal Cortex:

    • Executive processing; coordinates multiple functions to serve cognitive goals.

    • Involved in reason, logic, planning, emotion, and creativity.

    • Contributes to personality functioning.

  • Motor Cortex:

    • Coordinates voluntary body movements.

  • Broca’s Area:

    • Responsible for speech (typically in the left hemisphere).

    • Broca’s Aphasia:

      • Damage from head injury or stroke; loss or impairment of the ability to use or understand language.

      • Individuals know what they want to say but can speak very little or not at all.

• Parietal Lobes:

  • Involved in the reception and processing of touch stimuli.

  • Somatosensory Cortex:

    • Located in the front strip of brain tissue in the parietal lobes.

    • Site where touch, pressure, temperature, and pain register in the cerebral cortex.

    • Makes you aware of movement in your body & positions

    • Responsible for spatial orientation and sense of direction

• Occipital Lobes:

  • Involved in the reception and interpretation of visual information.

• Temporal Lobes:

  • Located slightly above the ears.

  • Involved in the reception and interpretation of auditory stimuli.

  • Wernicke’s Area:

    • Located adjacent to the primary auditory cortex in the left temporal lobe.

    • Language area involved in comprehending the spoken word and in formulating coherent written and spoken language.

    • Wernicke’s Aphasia:

      • Results from damage to Wernicke’s area.

      • The actual message does not make sense to listeners.

The Ever-Changing Brain

• The brain grows in spurts from conception until well into adulthood.

• Synaptogenesis:

  • Synapses develop as a result of the growth of both dendrites and axons.

• Pruning:

  • The process through which the developing brain eliminates unnecessary or redundant synapses.

• The brain’s plasticity – its capacity to adapt to changes such as brain damage – is maintained throughout life.

• Aging Brain:

  • Loss of synapses.

  • Decrease in brain weight.

Gender Differences in the Brain

• Generally, the more white matter, the more neural communication.

• Men have a higher proportion of white matter than women.

• Women’s superior emotion perception may be due to more gray matter in the right hemisphere.

• Men and women use different brain areas when searching for the location of a sound and when processing navigation info.

The Endocrine System

• A system of ductless glands that manufacture and secrete hormones into the bloodstream.

• Hormones affect cells in other parts of the body.

• Transmits messages through the bloodstream.

• The nervous system is faster, but the endocrine system is more enduring.

Glands

• Pituitary Gland:

  • Considered the master gland; regulates other glands and growth.

• Pineal Gland:

  • Produces and regulates the hormone melatonin.

• Thyroid Gland:

  • Regulates the rate at which food is metabolized, or transformed into energy.

  • Hypothyroidism:

    • Underactive thyroid; causes fatigue, weight gain, and depression.

  • Hyperthyroidism:

    • Overactive thyroid; causes being too thin, heart racing, and insomnia.

• Thymus Gland:

  • Produces hormones needed for specialized white blood cells production.

• Pancreas:

  • Regulates the body’s blood sugar levels by releasing insulin and glucagon into the bloodstream.

• Adrenal Glands:

  • Produce epinephrine and norepinephrine.

• Gonads:

  • Ovaries in females, testes in males.

  • Contain gender-specific hormones.

Genes and Behavioral Genetics

• Genes are segments of DNA located on chromosomes.

• Humans have 46 chromosomes.

• 22 pairs are autosomes.

• 23rd pair are sex chromosomes.

  • Male: XY

  • Female: XX

• Genotype:

  • An individual’s genetic makeup.

• Phenotype:

  • An individual’s actual traits.

• Dominant Gene:

  • Stronger gene.

• Recessive Gene:

  • Weaker gene.

• Polygenic Inheritance:

  • Many genes influence a particular characteristic.

• Multifactorial Inheritance:

  • Influenced by both genes and environmental factors.

• Sex-Linked Inheritance:

  • Involves the genes on the X and Y chromosomes.

Behavioral Genetics

• Behavioral genetics investigates the relative effects of heredity and environment (nature and nurture) on behavior.

• Twin Studies:

  • Behavioral geneticists study identical twins (monozygotic twins) and fraternal twins (dizygotic twins).

  • Determine how much they resemble each other on a variety of characteristics.

  • If identical twins raised together are more alike on a trait than fraternal twins raised together, then that trait is assumed to be more influenced by heredity.

  • If identical and fraternal twin pairs do not differ on a trait, then that trait is assumed to be influenced more by environment.

Genetic Counseling

• The purpose of genetic counseling is to estimate individuals’ risk of having a child with a genetic disorder or of developing an inherited disorder themselves.