Chapter 3

• Biopsychology is the scientific study of the biology behind behavior. Within a little over a century, researchers looking at the biology of the mind have discovered that:

  • the body is composed of cells
  • nerve cells conduct electricity and "talk" to each other by sending chemical messages to each other
  • specific brain systems serve specific purposes
  • we integrate info processed in different brain systems to construct our experience of sights and sounds, meanings and memories, etc.
  • our adaptive brain is wired by our experience
• Cells in the nervous system:

  • neurons (right) act as interconnected information processors; building blocks of nervous system; receive, conduct, and transmit electrochemical signals
  • glial cells provide physical and metabolic support to neurons; also neuronal insulation and communication, and nutrient and waste transport
• Neuron Structure:

  • semipermeable membrane: outer surface; allows small molecules and uncharged molecules to pass through, blocks all else
  • soma (cell body) houses the nucleus of the neuron
  • dendrites are the fibers that branch off from the soma; serve as input sites where signals are received from other neurons
• Neuron structure:

  • signals are transmitted electrically across the soma and down the axon, which ends at multiple terminal buttons
  • the terminal buttons contain synaptic vesicles that house neurotransmitters, the chemical messengers of the nervous system
  • some axons have a myelin sheath, which acts as a insulator, increasing the speed at which the signal travels
• How neurons communicate:

  1. dendrite
  2. soma
  3. action potential
  4. axon
  5. terminal buttons
  6. synapse
  7. dendrites
  8. soma
• How neurons communicate: resting potential

  • neurons are surrounded by extracellular fluid and contains intracellular fluid
  • the neuronal membrane keeps the two fluids separated
  • the difference in charge across the membrane is called the membrane potential and provide energy for the signal
• How neurons communicate: resting potential

  • between signals, the neurons membrane potential has resting potential; like a rubber band stretched out, waiting to spring into action
  • sodium potassium pump allows the movement of ions across the membrane
• How neurons communicate: threshold of excitation

  • when the neuron receives a signal, its state changes abruptly
  • pores open in the neuronal membrane allowing positive ions to come through
  • if charges reaches threshold of excitation, neuron becomes active
• How neurons communicate: action potential

  • as the additional pores open, this causes a positive spike constitutes the action potential
  • this action potential is the electrical signal that moves away from the cell body and down the axon
  • electrical signal moves down the axon in waves
  • action potential is an all-or-none phenomenon
• Neuron structure: synapses, neurotransmitters, and receptors

  • the synapse is the space between two neurons and site of communication
  • neurotransmitters are chemical messengers that bind receptors on the next neuron
  • receptors, proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes "matching" different neurotransmitters
• How neurons communicate: reuptake

  • reuptake involves moving a neurotransmitter from the synapse back into the axon terminal from which it was released
  • provides clear "on" and "off" states between signals and regulates production of the neurotransmitter
• Psychoactive drugs:

  • psychoactive drugs are chemicals that change brain function
  • agonists mimic a neurotransmitter at the receptor site and, thus, strengthen its effects
  • antagonists block the normal activity of a neurotransmitter at the receptor
  • reuptake inhibitors block the neurotransmitters from reentering the neuron
• The nervous system:

  • The central nervous system (CNS) consists of the brain and the spinal cord
  • The peripheral nervous system (PNS) is comprised of the somatic and autonomic nervous system (everything else); carries information between the CNS and the rest of the body
• Peripheral nervous system:

  • nerves in this system link the CNS with the rest of the body's sensory receptors, muscles, and glands
  • three types of neuron in this system:
  • sensory neurons carry messages from the body's tissue and sensory receptors inward to the CNS for processing
  • motor neurons carry instructions from the CNS out to the body's muscles
  • interneurons are neurons in the CNS that communicate internally intervene between sensory inputs and motor outputs
• The peripheral nervous system:

  • the somatic nervous system transmits sensory and motor signals to and from the CNS (efferent vs afferent)
  • the autonomic nervous system controls the function of our organs and glands, and can be divided into the sympathetic and parasympathetic divisions
• Autonomic nervous systems: parasympathetic and sympathetic

  • sympathetic activation prepares us for fight or flight (sometimes freeze); prepares body for stress
  • parasympathetic activation is associated with normal functioning under relaxed conditions
  • work together to crete homeostasis, or a state of equilibrium in which biological conditions are at optimal levels
• The endocrine system:

  • the endocrine system consists of a series of glands that produce chemical substances known as hormones
  • hormones regulate behaviors such as aggression, mating, and parenting of individuals
  • hormones are controlled by an interaction between the hypothalamus (CNS) and the pituitary gland
  • the study of psychology and the endocrine system is called behavioral endocrinology
• Parts of the endocrine system:

  • hypothalamus: brain region controlling the pituitary gland
  • pituitary gland is the "master gland;" secretes growth hormone, endorphins, oxytocin
  • thyroid gland regulates growth, metabolism, and appetite
  • parathyroids regulate levels of calcium in the blood
• Parts of the endocrine system:

  • adrenal glands produce epinephrine and norepinephrine; regulates fight or flight response
  • pancreas regulates blood sugar
  • gonads secrete sex hormones; ovaries in females and testes in males
• Central nervous system:

  • the brain is an organ comprised of billions of interneurons and glia cells
  • the spinal cord connects the brain to the outside world
• Spinal cord:

  • spinal cord stretches down from the brain stem
  • organized into 30 segments corresponding with vertebrae; each segment corresponds with specific parts of the body
  • some sensory inputs to the spinal cord are acted on immediately, without input from the brain; ex: withdrawal from heat, knee jerk
• The two hemispheres:

  • the brain is divided into left and right hemispheres
  • some specialization of function, known as lateralization, in each hemisphere; especially for language
  • left hemisphere controls right side of the body and vice versa
  • corpus callosum connects the two hemispheres; allows the two hemispheres to communicate
• Plasticity:

  • the brain's ability to change, adapt, and reorganize itself called brain plasticity
  • this can happen as a result of experiences or damages
  • severed neurons usually do not regenerate
  • some neural tissue can reorganize in response to loss of function or damage
• Regions of the brain:

  1. forebrain
  2. midbrain
  3. hindbrain
• Forebrain:

  • cerebral cortex: surface of the brain; associated with higher level processes
  • forebrain contains:
  • cerebral cortex
  • subcortical structures: thalamus, hypothalamus, pituitary gland, and limbic system
  • each of the hemispheres can be divided into fore lobes
• Frontal lobe:

  • contains the motor cortex involved in planning and coordinating movement
  • contains the prefrontal cortex responsible for higher-level cognitive functioning
  • contains Broca's area essential for language production
• The parietal lobe:

  • contains the somatosensory cortex which processes sensory information
  • organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex
• The temporal lobe:

  • contains the auditory cortex which processes auditory information and wernicke's area which is important for speech and comprehension
  • also associated with memory and emotion
• The occipital lobe:

  • contains the primary visual cortex, which interprets visual information
  • organized retinotopically, which means there is a close relationship between the position of an object in a person's visual field and the position of that object's representation on the cortex
• Thalamus: the thalamus serves as the relay center of the brain where most senses are routed for processing
• The limbic system:

  • amygdala is the structure involved in our experience of emotional meaning to our memories; linked to aggression and fear
  • hippocampus is the structure associated with learning and memory
  • hypothalamus is the structure that regulates sexual motivation and behavior and a number of homeostasis processes; serves as an interface between the nervous system and the endocrine system
• Midbrain:

  • the substantia nigra ("black substance") and the ventral tegmental area (VTA) contain cell bodies that produce the neurotransmitter dopamine and are critical for movement
  • the reticular formation is centered in the midbrain and is important in regulating the sleep/wake cycle, arousal, alertness, and motor activity
• The hindbrain:

  • medulla controls the autonomic nervous system
  • pons connects the brain and the spinal cord; regulates sleep
  • cerebellum controls balance, coordination, movement, and motor skills; procedural memory
  • the medulla, pons, and the midbrain make up the brainstem
• Brain imaging technology:

  • computerized tomography (CT) scan: imaging technique in which a computer coordinates and integrates multiple x-rays of a given area
  • magnetic resonance imaging (MRI): magnetic fields used to produce a picture of the tissue being imaged
  • functional magnetic resonance imaging (fMRI): MRI that shows changes in metabolic activity over time
• Brain imaging technology:

  • electroencephalography (EEG): recording the electrical activity of the brain via electrodes on the scalp
  • position emission tomography (PET) scan: involves injecting individuals with a mildly radioactive substance and monitoring changes in blood flow to different regions of the brain
• Ways to study nature/nurture:

  • adoption studies: behavior genetic research method that compares adopted children to adoptive and biological parents
  • twin studies: compares similarity of identical twins (monozygotic) and fraternal twins
  • qualitative genetics: scientific discipline in which similarities among individuals are analyzed based on how biologically similar they are
• Human genetics:

  • the theory of evolution by natural selection says that organisms that are better suited for their environment will survive and reproduce
  • genetic variety contributes to a species' adaptation to its environment; mutation; sudden, permanent change in a gene
• Gene environment interactions:

  • the range of reaction: genes set definite limits on potential, and environment determines how much of that potential is achieved
  • genetic environmental correlation: our genes influence our environment, and our environment influences the expression of our genes
  • epigenetics: studies how the same gene can lead to different results