The Biology of Mind Chapter 2

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The Biology of Mind Chapter 2
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Biological Psychologists

• Study links between biological activity and
  behavior
• Also called neuroscientists, neuropsychologists,
  biopsychologists, physiological psychologists,
  behavior geneticists
• Cells ? brain ? behavior ? environment
• Environment ? behavior ? brain ? cells

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Neural Communication

• Neurobiologists and other investigators
  understand that humans and animals operate
  similarly when processing information.

Note the similarities in the above brain regions,
which are all engaged in information processing.
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Building Blocks of the Nervous System

• Neurons cells specialized to receive and
  transmit information in the nervous system
• Brain is more complex than a computer but a
  little slower!
• 
  

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Parts of a Neuron

• Cell Body Life support center of the neuron.
• Dendrites Branching extensions at the cell body.
  Receive messages from other neurons.
• Axon Long single extension of a neuron, covered
  with myelin sheath to insulate and speed up
  messages through neurons.
• AWAY
• Axon speaks, cell body interprets, dendrites
  listen
• Terminal Branches of axon Branched endings of an
  axon that transmit messages to other neurons.

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Kinds of Neurons

• Sensory Neurons carry incoming information from
  the sense receptors to the CNS.
• Motor Neurons carry outgoing information from
  the CNS to muscles and glands.
• Interneurons located within the brain and spinal
  chord they connect the two neurons.

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Building Blocks of the Nervous System

• Neurons receive energy from the environment
  (i.e., light, sound, touch, heat) and change it
  to an electrical energy.
• Transduction
• Process in which neurons transform energy from
  the environment into electrical energy.
• Action potential
• The electrical signals that contain information
  about the experience (i.e., hearing a sound
  looking at a cat).
• Information travels down the axon of that neuron
  to the dendrites of another neuron.

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Action Potential

• A neural impulse. A brief electrical charge that
  travels down an axon and is generated by the
  movement of positively charged atoms in and out
  of channels in the axons membrane.
• The action potential propagates down the axon,
  without decreasing in size.

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How to measure an action potential?

• The size of action potential remains consistent.
• all or none release of electric charge
• The intensity of an action potential remains the
  same throughout the length of the axon.
• The rate of firing is measured (i.e., frequency)
• Low stimuli intensities slow firing and/or
  triggers less neurons to fire
• High stimuli intensities fast firing and/or
  triggers more neurons to fire

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Rate of action potential
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How Neurons Communicate

• Information passes from neuron to neuron in the
  brain.
• An electrical signal travels down the axon and
  then is transmitted to the dendrite of another
  neuron.
• Neurons are not connected with each other. The
  synapse is a gap between the axon of a neuron and
  the dendrite of another neuron.
• When the action potential reaches the end of the
  axon, synaptic vesicles open and release
  neurotransmitters which are picked up by the
  receiving dendrites.

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Synapse

• Synapse a junction between the axon tip of the
  sending neuron and the dendrite or cell body of
  the receiving neuron.
• This tiny gap is called the synaptic gap or cleft.

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Neurotransmitters

• Neurotransmitters are made by the brain or can be
  consumed artificially through Rx.
• Excitatory increases neuron firing
• Inhibitory decreases neuron firing

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Reuptake

• Neurotransmitters in the synapse are reabsorbed
  into the sending neurons through the process of
  reuptake.
• This process applies the brakes on
  neurotransmitter action.

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Neurotransmitters
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For Fun!

• What happens if you flood the brain with
  acetylcholine?
• What drug does this? (bwsv)
• What happens if you flood the brain with
  endorphins?
• What drug does this? Natural? Artificial?
• What happens if you block the re-update of
  seratonin?
• What drug does this?
• What happens if you block acetylcholine?
• What drug does this?

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Lock Key Mechanism

• Neurotransmitters bind to the receptors of the
  receiving neuron in a key-lock mechanism.

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Nervous Systems
Central Nervous System (CNS)
Peripheral Nervous System (PNS)
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The Nervous System

• Nervous System Consists of all the nerve cells.
  It is the bodys speedy, electrochemical
  communication system.
• Central Nervous System (CNS) the brain and
  spinal cord.
• Peripheral Nervous System (PNS) the sensory and
  motor neurons that connect the central nervous
  system (CNS) to the rest of the body.

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The Nervous System
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Peripheral Nervous System

• Somatic Nervous System The division of the
  peripheral nervous system that controls the
  bodys skeletal muscles.
• Under the individuals control
• Autonomic Nervous System Part of the PNS that
  controls the glands and other muscles.
• Not under the individuals control
• Think automatic

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Autonomic Nervous System (ANS)

• Sympathetic Nervous System Division of the ANS
  that arouses the body, mobilizing its energy in
  stressful situations.
• Parasympathetic Nervous System Division of the
  ANS that calms the body, conserving its energy.

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Autonomic Nervous System (ANS)

• Sympathetic NS Arouses
• (fight-or-flight)
• Parasympathetic NS Calms (rest and digest)
• Think parachute brings you down

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Central Nervous System

• Interconnected neurons form networks in the
  brain.
• These networks are complex and modify with growth
  and experience.

Complex Neural Network
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The Spinal Cord and Reflexes

• Certain reflexes are simple and do not involve
  the brain in order to respond.
• These reflexes travel to the spinal cord, only.

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The Endocrine System

• The Endocrine System is the bodys slow
  chemical communication system.
• Communication is carried out by hormones
  synthesized by a set of glands.

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Hormones

• Hormones are chemicals synthesized by the
  endocrine glands that are secreted in the
  bloodstream. Hormones affect the brain and many
  other tissues of the body.
• For example, epinephrine (adrenaline) increases
  heart rate, blood pressure, blood sugar, and
  feelings of excitement during emergency
  situations.

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Cognitive Processes and the Brain

• Cerebral cortex
• External regions of the brain, about 3mm deep
• Contains mechanisms responsible for most of our
  higher mental functions.

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Cognitive Processes and the Brain

• Temporal lobe language, memory, hearing,
  perceiving forms
• Occipital lobe vision
• Parietal lobe touch, vision, attention
• Frontal lobe language, thought, memory, motor
  functioning

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The Cerebral Cortex

• It is the bodys ultimate control and information
  processing center.

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Cognitive Neuroscience

• Cognitive psychology neuroscience
• To study how the brain functions and gives rise
  to mental processes.
• To correlate brain regions with specific
  processes.
• Use of technology to study brain regions.
• Brain imaging techiniques.

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Electroencephalogram (EEG)
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Magnetic Resonance Imaging machine
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Magnetic Resonance Imaging (MRI)
3 dimensional image of brain
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Positron Emission Tomography (PET)
PET (positron emission tomography) Scan is a
visual display of brain activity that detects a
radioactive form of glucose while the brain
performs a given task .
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Functional Magnetic Resonance Imaging (fMRI)
Measures ratio of oxygenated blood to
deoxygenated blood. Iron in blood is detected by
the magnet in the scanner. Areas in yellow
indicate more activation (more blood flow).
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Language
Aphasia is an impairment of language, usually
caused by left hemisphere damage either to
Brocas area (impaired speaking) or to Wernickes
area (impaired understanding).
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Specialization Integration

• Brain activity when hearing, seeing, and speaking
  words.
• Several brain regions are used simultaneously for
  certain mental functions.

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Nervous System Interacts with Environment

• Brain adapts to environment
• Brain can change to respond best to what is
  commonly encountered.
• Plasticity
• refers to the brains ability to modify itself
  after some types of injury or illness.
• Brains exposed to different environmental
  experiences, injury, hormonal levels or genetic
  abnormalities, are molded in different ways.
• Ex right handed vs. left handed individuals
• young brain vs. older brain

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Splitting the Brain

• A procedure in which the two hemispheres of the
  brain are isolated by cutting the connecting
  fibers (mainly those of the corpus callosum)
  between them.

Corpus Callosum
Courtesy of Terence Williams, University of Iowa
Martin M. Rother
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Split Brain Patients

• With the corpus callosum severed, objects (apple)
  presented in the right visual field can be named.
  Objects (pencil) in the left visual field cannot.

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Divided Consciousness
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Right-Left Differences in the Intact Brain

• People with intact brains also show left-right
  hemispheric differences in mental abilities.
• A number of brain scan studies show normal
  individuals engage their right brain when
  completing a perceptual task and their left brain
  when carrying out a linguistic task.
• Right-handed people more likely process speech in
  the left hemisphere.
• Left-handed people more likely process speech in
  both hemispheres.