Transcript PHYSIOLOGICAL PSYCHOLOGY Chapter 2

The World of Psychology
Wood and Wood
Physiological Psychology
Chapter 2
Some Definitions

The Neurons and the
Neurotransmitters

Neurons appear in many forms,
but all possess the three basic structures:
• a cell body
• an axon (with axon terminals)
• one or more dendrites.
There are Three Types of Neurons
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Afferent (Sensory)
Efferent (Motor)
Interneurons
The Neuron
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Dendrite
Cell body
Axon
The Life and Death of a Neuron
The Neuron
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 Dendrite
 Cell
body
 Axon
The Neural Impulse
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Resting Potential
Action Potential
All or None law
Resting Potential

The definitive reference guide to neuron
potential:
http://www.biol.sc.edu/~vogt/courses/neuro/neuroAP.html
 All about the electrical properties of a cell:
http://artsandscience.concordia.ca/psychology/psyc358/Lectures/restp
otent1.htm
Resting Potential –The whole story
The potential difference that exists across the membrane of all cells is usually negative inside the cell with respect to
the outside. The membrane is said to be polarized. The potential difference across the membrane at rest is called the
resting potential and is approximately -70 mV in neurons. (The negative sign indicates that the inside of the cell is
negative with respect to the outside.) The establishment of this potential difference involves several factors, most
importantly the transport of ions across the cell membrane and the selective permeability of the membrane to these
ions.
The active transport of potassium and sodium ions into and out of the cell, respectively, is accomplished by a number
of sodium-potassium pumps scattered across the cell membrane. Each pump transports two ions of potassium into the
cell for every three ions of sodium pumped out. This establishes a particular distribution of positively charged ions
across the cell membrane, with more sodium present outside the cell than inside, and more potassium inside the cell
than outside. In some situations, the electrogenic sodium-potassium pumps make a significant contribution to the
resting membrane potential, but in most cells there are special potassium channels ("leak channels") that dominate the
value of the resting potential.
The natural tendency of sodium and potassium ions is to diffuse across their electrochemical gradients to attempt to
reach their respective equilibrium potentials, with sodium diffusing into the cell and potassium diffusing out.
However, the resting cell membrane is approximately 100 times more permeable to potassium than to sodium, so that
more potassium diffuses out of the cell than sodium diffuses in. This permeability to potassium is due to potassium
leak channels that are always open. As a result, the dominant outward leak of potassium ions produces a
hyperpolarizing current that establishes the cell's resting potential of roughly -70 mV.
From: http://en.wikipedia.org/wiki/Action_potential#Resting_potential
Axons are like wastebaskets
– well, sorta…
Action Potential

The Action Potential
(Top)During an action potential,
positively charged particles enter the
membrane through specialized ion
channels, thereby momentarily
eliminating the negative charge just
inside the neuron’s membrane.
Movement of this disturbance along the
membrane constitutes the action
potential.
(Bottom) After a brief period, however,
positively charged particles are forced
outside of the neuron’s membrane
via the ion channels.
Action potential in Action
The impulse (red) moves along the axon.
Action Potential Details
http://people.eku.edu/ritchisong/301notes2.htm
Source:
http://faculty.washington.edu/chudler/ap.html
All or None law

• Law refers to the activity of a single neuron.
• A neuron will either fire or it will not.
• When it fires, it fires with the same intensity
every time.
• Implications for nervous system communication
• Because the intensity is always the same,
variability come from somewhere else.
• That variability is the rate of nerve impulses.
All or None law

• Law implies the central nervous system is binary.
• What is binary?
B Definition
• Information is encoded as frequency coding.
• What is Frequency Coding
FC Definition
Additional info:
http://zadorlab.cshl.edu/PDF/deweese-zador2002.pdf
The Synapse

 Axon
Terminal
 Synaptic Vesicles
 Synaptic Cleft
http://people.eku.edu/ritchisong/301notes2.htm
Neurotransmitters
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Acetycholine
 Monoamines (Serotonin, Dopamine,
epinephrine, norepinephrine)
 Amino Acids
 Endorphins
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Neurotransmitters: Their Basic Effects
Neurotransmitters exert one of
two basic effects on neurons. If
the neurotransmitter is excitatory
the neuron’s cell membrane becomes
depolarized (the charge becomes more
positive); it increases the likelihood that
an action potential will occur.
In contrast, if the neurotransmitter
is inhibitory the cell membrane
of a neuron becomes hyperpolarized
(the charge becomes more negative); its
effects decrease the likelihood that an
action potential will occur.
Neurotransmitters: Their Specific Effects
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Acetycholine
Found throughout the central nervous system, in the autonomic
nervous system, and at all neuromuscular junctions.
Involved in muscle action, learning,and memory.
Norepinephrine
Found in neurons in the autonomic nervous system.
Primarily involved in control of alertness and wakefulness.
Dopamine
Produced by neurons located in a region of the brain called the
substantia nigra.Involved in movement, attention, and learning.
Degeneration of dopamine-producing neurons has been linked to
Parkinson’s disease.
Too much dopamine has been linked to schizophrenia.
Neurotransmitters: Their Specific
Effects

Serotonin
Found in neurons in the brain and spinal cord. Plays a role in
the regulation of mood and in the control of eating, sleep, and
arousal. Has also been implicated in the regulation of pain
and in dreaming.
GABA (gamma-amino-butyric acid)
Found throughout the brain and spinal cord.GABA is the
major inhibitory neurotransmitter in the brain.
Abnormal levels of GABA have been implicated in sleep and
eating disorders.
Neurotransmitters: Endorphins

Endorphins were first discovered during the 1970s by
researchers studying the effects of morphine and other
opiates. To their surprise, the researchers learned there were
special receptor sites for such drugs within the brain
(Hughes et al., 1975).
Why should such receptors exist?
• Naturally occurring substances that closely resemble
morphine in physical structure are produced by the brain.
• These substances, known as endorphins, act as
neurotransmitters, stimulating specialized receptor sites.
Neurotransmitters: More Endorphins
Why should the brain produce such substances?
• Endorphins are released by the body in response to
• pain or
• vigorous exercise
• Help reduce sensations of pain
• that might otherwise interfere with ongoing activity
(Fields & Basbaum, 1984).
• Endorphins also serve to intensify positive sensations
For example, the “runner’s high”
Pain Management – Value & Effects
Psychoactive Drugs
How they work

They CAN effect the
neurotransmitters.
Psychoactive Drugs
How they work 2
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Psychoactive drugs exist because:
• They are produced in nature
OR
• They are produced artificially by man
• They mimic the brain’s own neurotransmitters
OR
• They affect the brain’s own neurotransmitters actions
AND
• They cross the blood brain barrier!
The Nervous System
Copyright © Allyn & Bacon 2002
The Central Nervous System
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Brain
Cerebellum
 Thalamus
 Hypothalamus
 Limbic System
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Neurons
Cortex
Spinal Cord
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links the body with
the brain
Brainstem
Medulla
 Reticular Formation
 Pons
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Cerebral Hemispheres
 Lobes
of the Brain
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Frontal lobes
 Parietal lobes
 Occipital lobes
 Temporal lobes
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Other Structures
Cerebellum
 Motor cortex
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Frontal Lobe- reasoning, planning, parts of speech,
movement, emotions, and problem solving
Parietal Lobe- movement, orientation, recognition,
perception of stimuli
Occipital Lobe- visual processing
Temporal Lobe- perception and recognition of auditory
stimuli, memory, and speech
Major Structures of the
Human Brain
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Cerebral Cortex
Corpus Callosum
Thalamus
Cerebellum
Reticular Formation
Medulla
Pons
Pituitary Gland
Hypothalamus
The Limbic System
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Hypothalamus
Amygdala
Corpus Callosum
Pituitary Gland
Hippocampus
Another View
Brain Hemispheres
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 Left
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Brain
Language
mathematics
Logic
Right Side
Movement
 Right
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Brain
Music
Art
Spatial Skills
Creativity
Intuition
Emotion
Brain Waves
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Beta (Mental or Physical Activity)
Relatively low amplitude, and are the fastest of the four different brainwaves. The frequency
of beta waves ranges from 15 to 40 cycles a second. Beta waves are characteristics of a
strongly engaged mind.
Alpha (Deep Relaxation)
Alpha represents non-arousal. Alpha brainwaves are slower, and higher in amplitude. Their
frequency ranges from 9 to 14 cycles per second. A person who has completed a task and
sits down to rest is often in an alpha state.
Theta (Light Sleep)
Even greater amplitude and slower frequency. This frequency range is normally between 5
and 8 cycles a second. A person who has taken time off from a task and begins to daydream
is often in a theta brainwave state.
Delta (Slow Wave Sleep)
Greatest amplitude and slowest frequency, centered around a range of 1.5 to 4 cycles per
second. Deep dreamless sleep goes down to the lowest frequency - typically, 2 to 3 cycles a
second.
Discovering the Brain’s Mysteries
EEG
 CT Scan
 MRI
 PET Scan
 fMRI
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More on EEGs
More on CT Scan
More on
PET Scan
Gender Differences
MEN AND WOMEN DIFFER IN BRAIN
USE DURING SAME TASKS
A man's brain and a woman's brain really do
work differently.
New research from the University of Alberta
shows that men and women utilize different
parts of their brains while they perform the
same tasks. http://www.physorg.com/news8634.html
More Gender Differences
BRAIN DIFFERENCES COULD EXPLAIN WHY
MALES AND FEMALES EXPERIENCE PAIN RELIEF
DIFFERENTLY
•Study conducted by investigators at Georgia State
University and the Atlanta-based Center for Behavioral
Neuroscience (CBN)
•Anatomical and functional differences in the brain may
explain sex differences in the experience of pain and in the
effects of certain drugs on pain.
Full story at http://www.physorg.com/news64588700.html
Age - Youth
TEENS UNDERGO FAST BRAIN MAKEOVER
a teen's brain undergoes a previously unsuspected
biological makeover not complete until they're 25, and
that could explain a few things. Full story at
http://www.physorg.com/news12113.html
BRAIN CHANGES SIGNIFICANTLY AFTER 18
study aimed at identifying how and when a person's brain
reaches adulthood,
 anatomically, significant changes in brain structure continue
after age 18.Full story at
http://www.physorg.com/news10581.html
Age - Elderly
Exercise – body and brain
 aerobics fights brain shrinkage
http://www.physorg.com/news82922696.html
Walking decreases apparent age in nursing
home patients.
Video Games?
http://www.boston.com/news/science/articles/2007/01/08/little_proof_tha
t_brain_exercises_can_prevent_mental_decline/
Food and Training
 Brain Training Can Have Lasting Benefits
URL: http://www.physorg.com/news85769096.html
 Reading Shakespeare has dramatic effect on human brain
URL: http://www.physorg.com/news85664210.html
 Eating Berries Neurobiology of Aging, Tufts psychologist Barbara ShukittHale and her colleagues say a diet rich in berries improved the brain
function of aging rats
 DIET SEEN TO CUT ALZHEIMER'S RISK SHARPLY
A Columbia University study has found that the Mediterranean diet rich
in olive oil can reduce the risk of Alzheimer's disease by up to 40
percent. http://www.physorg.com/news64580999.html
 Fish Oil[Omega 3 fatty acids]
The evidence is overwhelming and may even be the cause of humans
winning the “hominid wars.”
The Peripheral Nervous System
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Somatic Nervous
System
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Controls skeletal muscles
interacts with external
environment
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Autonomic Nervous
System
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Sympathetic Nervous
System
Mobilizes
Parasympathetic Nervous
System
Rescues
The Endocrine System
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Pituitary Gland (Master Gland)
Thyroid Glands
Pancreas
Adrenal Glands
Ovaries and Testes
End
That’s as far as we get.