Chapter 2: Biological Foundations of Behavior

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Chapter 2 Biological Foundations of Behavior

• Michael L. Farris
• Psychology 101

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Nervous System

• Autonomic nervous system - The division of the
  nervous system that regulates the bodys inner
  environment (heart rate, blood pressure,
  digestion, pupil dilation, and electrical
  conductance of the skin.) Pgs. 50-51.
• Afferent Nerves (advance, arrive, approach)
  carry sensory signals from internal organs TO the
  CNS (brain and spinal cord). Up. p.40.
• Efferent nerves (Exit, Embark, Escape p. 52)
  carry motor signals away from the central nervous
  system TO the skeletal muscles. Down. P.41.
• Afferent and efferent nerves are also known as
  sensory neurons (p. 40).

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The Blood-Brain Barrier

• Blood-Brain Barrier (Pinel, p. 55) The brain
  is a finely tuned electrochemical organ whose
  function can be severely disturbed by the
  introduction of certain kinds of chemicals.
• Fortunately, there is a mechanism that impedes
  the passage of many toxic substances from the
  blood into the brain the blood-brain barrier.

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The Brain Stem

• Brain Stem The part of the brain on which the
  cerebral hemispheres rest in general, it
  regulates reflex activities that are critical for
  survival (heart rate and respiration). The Brain
  Stem (particularly the medulla) regulates basic
  life functions (heart rate and breathing, and
  such reflexes as swallowing, coughing, and
  sneezing). P. 53.

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Cerebral Hemispheres, Corpus Callosum

• The brain is composed of two sides, or
  hemispheres.
• Left Brain Controls language, speech, writing,
  calculation, time sense, rhythm, and the ordering
  of complex movements.
• Right Brain Non-verbal. Controls perceptual
  skills, visualization, recognition of patterns,
  faces, and melodies, recognition and expression
  of emotion, spatial skills, and simple language
  comprehension.
• The left and right hemispheres are joined
  together by the Corpus Callosum, a structure in
  the middle of the brain that enables hemispheres
  to share functions and information.
• Please see pages 54-54 in your text for more
  information.

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Case Studies

• Studies that focus on a single case or
  subject.
• Detailed
• In-depth
• Pro Good source of testable hypotheses.
• Con not very easy to generalize to others.
• Humans differ be skeptical of any
  biopsychological theory based on only a few case
  studies. P.23.
• Example Lobotomy (1 primate study)

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CNS and Cerebral Cortex

• Central Nervous System (CNS) The portion of the
  nervous system within the skull and spine.
• Composed of 2 divisions Brain and Spinal Cord.
• Cerebral Cortex - The layer of neural tissue
  covering the cerebral hemispheres of humans and
  other mammals. Being the OUTER layer, it is most
  likely to be damaged by accident or surgery.
• Please see pages 47-50 for more information.

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Thinking and Learning

• Cerebrum - The portion of the brain that sits
  on the brain stem in general, it plays a role in
  complex adaptive processes (like learning,
  perception, and motivation). P.54.
• Cognition - Complex intellectual processes such
  as thought, memory, attention, and perceptual
  processing. p.11.

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Comparative Psychology

• Comparative Psychology - The division of
  Biopsychology that studies the
• evolution, genetics, and adaptiveness of
  behavior, often by using the comparative
• method (The study of biological processes
  by comparison of different species). P.15.

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Convolutions

• Folds on the surface of the cerebral
  hemispheres.
• Folds have increased over time
• greatly increased the volume of the cerebral
  cortex (the outermost layer of cerebral tissue).
• More surface area more capacity

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DNA, EEG, and Evolution

• Deoxyribonucleic acid (DNA) Double Stranded,
  coiled molecules of genetic material. The basic
  chemical material in chromosomes that carries the
  individuals genetic code. (p.72).
• Electroencephalograph (EEG) - A measure of the
  general electrical activity of the brain, often
  recorded through the scalp. Pgs. 58-59.
• Evolve - To undergo gradual orderly change. P.10.

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Myelin

• Myelinated Nerves carry signals 200 times FASTER
  than unmyelinated ones.
• (Axons vary in length from 0.04 inches to 1
  yard.)
• The fastest nerve signals travel at over 250 mph.
  
• Nerve signals enter a neuron through its
  dendrites and rush along the axon. At the far
  end, called the nerve-ending, the axon has other
  dendrites that pass the message on to the
  dendrites of other neurons.
• Neurons that have to carry urgent signals over
  long distances are surrounded by thick insulation
  to keep the signal strong, in the same way that
  the cable from a TV aerial to the TV is coated
  with insulating plastic.
• In the case of neurons, the insulation is a
  myelin sheatha series of long, flat cells
  wrapped around the axon. In people with the
  crippling disease multiple sclerosis, the sheaths
  break down, weakening the nerve signals. Pgs.
  41-42.

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Natural Selection

• Heritable traits that are associated with
  high rates of survival and reproduction are
  preferentially passed on to future generations.
  (No magic here simply good traits get
  reproduced.)
• For example, fast horses are selected and
  bred by racehorse breeders, so each succeeding
  generation gets faster overall. The slow ones
  dont get a chance to reproduce and pass on their
  slower genes. Nature is similar. The slow fish
  cant outrun the shark, so doesnt get to
  reproduce.

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Nature/Nurture and PNS

• Nature-nurture issue - The debate about the
  relative contributions of nature (genes) and
  nurture (experience) to the behavioral capacities
  of individuals. Pgs. 72-73.
• Peripheral Nervous System (PNS) The division
  located outside the skull and spine. Composed of
  2 divisions
• Somatic nervous system (SNS) (the part of the PNS
  that interacts with the external environment)
• Autonomic nervous system (ANS), the part which
  participates in the regulation of the internal
  environment. Pgs. 47-49.

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Lobotomy and Spinal Cord

• Prefrontal Lobes - The large areas, left and
  right, at the very front of the brain.
• Prefrontal Lobotomy - A surgical procedure in
  which the connections between the prefrontal
  lobes and the rest of the brain are cut as a
  treatment for mental illness.
• Spinal Cord comprises 2 different areas
• Gray Matter (composed largely of cell bodies and
  unmyelinated interneurons)
• White Matter (composed largely of myelinated
  axons.) It is the myelin that gives the white
  matter its glossy white sheen.

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Sympathetic and Parasympathetic Nerves

• Sympathetic nerves stimulate, organize, and
  mobilize energy resources in threatening
  situations. Sympathetic changes are indicative of
  psychological arousal.
• Parasympathetic nerves act to conserve energy.
  Parasympathetic changes are indicative of
  psychological relaxation (think of a parachute).
• Each autonomic target organ receives opposing
  sympathetic and parasympathetic input, and its
  activity is thus controlled by relative levels of
  sympathetic and parasympathetic activity. P.51.

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Brain Anatomy

• Early brain development 3 sections form
  (forebrain, midbrain, and hindbrain).
• Later, these grow into five major different
  swellings (telencephalon, diencephalons,
  mesencephalon (midbrain), metencephalon, and
  myelencephalon).
• ENCEPHALON means within the head. In humans,
  the telencephalon (right and left cerebral
  hemispheres) undergo the greatest growth during
  development.
• The other 4 divisions are often referred to
  collectively as the Brain Stem, on which the
  cerebral hemispheres sit. The myelencephalon is
  often referred to as the medulla.
• Again Brain Stem myelencephalon,
  metencephalon, mesencephalon, and
• diencephalon. 4 of 5 divisions are in the
  stem.

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Brain and Spine Protectors

• Meninges, Ventricles, and Cerebrospinal Fluid
  (Pinel p. 53) The brain and spinal cord (the
  CNS) are the most protected organs in the body.
  They are encased in bone and covered by three
  protective membranes, the meninges.
• Also protecting the CNS is cerebrospinal
  fluid, which fills the central canal of the
  spinal cord and the cerebral ventricles of the
  brain. It also fills the subarachnoid space,
  which contains many large blood vessels.
• The cerebral ventricles are the four large
  internal chambers of the brain 2 lateral
  ventricles, the third ventricle, and the fourth
  ventricle. It is believed that the ventricles
  are often enlarged in people with schizophrenia.

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Neural Conduction and Synaptic Transmission

• Neural ConductionElectrical (the way a nerve
  impulse travels along a nerve cell.
• Synaptic TransmissionChemical (the way
  neurotransmitters travel across the synapse (gap)
  to communicate with another nerve cell (neuron).

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Neural Conduction/Synaptic Transmission

• Nerve signals are constantly whizzing from neuron
  to neuron all around your body yet no two
  neurons ever actually touch. Instead, there is a
  small gap between connecting neurons called a
  synapse.
• When a nerve signal is passed on from one neuron
  to the next, it is carried across the gap by
  special chemicals called neurotransmitters. The
  chemicals are released by the neuron that is
  sending the signal.
• Droplets of neurotransmitters are stored inside
  the nerve-ending in tiny sacs called vesicles.
  When a nerve signal arrives at the nerve-ending,
  the vesicles drift towards the synapse and spill
  out their contents into the gap. The
  neurotransmitters flood across the gap and wash
  up against the other nerve. Inside every nerve
  ending are sacs of chemical transmitters. These
  are released into the synapse when the nerve is
  activated, or excited, by a nerve signal. If
  the adjoining nerve has the right receptors (page
  95), the signal will pass on.

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Neural Conduction and Synaptic Transmission

• The term exocytosis (Pinel pages 94-95) refers to
  the process of releasing a neurotransmitter.
• Neurotransmitter chemicals work a bit like keys
  in locks. In this case, the locks are special
  receptor sites in the dendrites of the receiving
  neuron.
• These sites accept only one kind of chemical.
  For the nerve signal to pass on, the
  neurotransmitter must be the right chemical that
  fits, or unlocks, the receptor site. If the
  neurotransmitter fits, it changes the chemistry
  of the receiving nerves membrane (skin). This
  starts off the electrical charges that pass the
  signal along the length of the neuron.
• Because a receptor site responds only to one type
  of neurotransmitter, an active nerve will pass on
  the signal only to neurons that have the right
  receptors, even though it is linked to many
  others. Pgs.40,43-44.

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Excitation and Inhibition

• Different types of signals follow different
  routes through the body.
• If every single nerve signal were passed on by
  every single synapse, you would simply be
  overwhelmed by nerve signals. This is why at
  some synapses the receiving neurons react by
  passing on the signal, but at others they react
  by blocking it.
• This is called excitation and inhibition.

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Neurotransmitters

• There are more than 40 different
  neurotransmitters
• Noradrenaline helps to control heartbeat and
  blood flow
• Dopamine works in the areas of the brain that
  control movement and coordination (when youre
  making a tricky move on a skateboard, your nerve
  endings are releasing lots of dopamine, a
  neurotransmitter that helps muscles move more
  easily).
• Endorphins are used by the brain to control pain
  (they are called endogenous opiatesliterally,
  opiumlike chemicals that are produced within the
  body see page 100 for more information).
• Acetylcholine is involved in making muscles
  contract
• When you wake up in the morning, it is because
  certain nerves are flooding your brain with the
  neurotransmitter serotoninand any nerve that is
  receptive gets an alarm call!