Transcript Psychology 2520 - Play Psych Mun

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http://dogsbody.psych.mun.ca/
http://www.mun.ca/psychology/
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Mind and
Brain
Chapter 1
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Jeff Hawkins, in his book “On
Intelligence”, wrote:
 “Most
big scientific questions involve the
very small, the very large, or events that
occurred billions of years ago. But
everyone has a brain. You are your brain. If
you want to understand why you feel the
way you do, how you perceive the world,
why you make mistakes, how you are able
to be creative, why music and art are
inspiring, indeed what is is to be human,
then you need to understand the brain.”
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Carlson, in “Physiology of
Behavior” wrote:
 “The
last frontier in this world – and perhaps the
greatest one – lies within us.”
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Overview

Mind-brain question

Understanding human consciousness


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Blindsight
Split brain
Unilateral neglect
Phantom limb, Capgras syndrome, Temporal lobe epilepsy

The nature of physiological psychology

The goals of research

Biological Roots of Physiological Psychology

Natural selection and evolution

Ethical issues in research with animals

Careers in neuroscience
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Mind-Body Question
 Mind, soul, spirit

We are aware of our own existence
 What
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role does the mind play?
Does the mind control the NS?
 Is
it physical and tangible?
 Is
it a spirit that will always remain hidden?
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Mind-body question
 People
have followed 2 different approaches:
 Dualism

Is a belief in the dual nature of reality; the body is physical
but the mind is not
 Monism
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Is the belief that the world consists only of matter and
energy and that the mind is a phenomenon produced by
the workings of the nervous system
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Mind-body question
 Physiological
Psychologists take an empirical,
practical and monistic approach to this question
 Once
we understand how the body, and especially
the brain, works the mind-body problem will be
solved
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How we perceive
How we think
How we remember
How we act
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Understanding Human
Consciousness: A Physiological
Approach
 Consciousness
refers to the fact that humans are
aware of – and can tell others about – our thoughts,
perceptions, memories, and feelings.
 Is
it possible to understand this very complex
phenomenon using a scientific approach?
 Consciousness
can be altered by changes in the
brain – therefore we may hypothesize that
consciousness is a physiological function
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Understanding Human
Consciousness: A Physiological
Approach
 Blindsight
 Split
Brains
 Unilateral
neglect
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Blindsight
 The
ability of a person who cannot see objects in
his or her blind field to accurately reach for them
while remaining unconscious of perceiving them
 Caused
by damage to the “mammalian” visual
system of the brain
 Visual
information can control behavior without
producing a conscious sensation
 Suggests
consciousness is not a general property
of the brain

Some parts of the brain are more important than others in
consciousness
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Split Brains
 Cerebral

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
two symmetrical halves of the brain
Receive sensory information from the opposite side of the
body
Control movement of opposite side of the body
 Corpus


Hemispheres
Callosum
largest commissure of the brain, interconnecting the areas
of neocortex on each side of the brain.
Allows each side of the brain to know what the other is
doing
Copyright © 2006 by Allyn and Bacon
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Figure 1.3 The Split-Brain Operation
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Commissurotomy in Human
Epileptics
 Commissurotomy

Many never have another major convulsion
 Sperry
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2
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& Gazzaniga
Developed procedures to test split-brain patients
 The
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limits convulsive activity
two hemispheres work independently
Sensory mechanisms, memories, and motor systems can no longer
exchange information
hemispheres have very different abilities
Most left hemispheres are capable of speech, while the right aren’t
Copyright © 2006 by Allyn and
Bacon
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Figure 1.4 Smelling with a Split Brain
Important point: we become conscious of something only if information about it
reaches the part of the brain responsible for verbal communication (left
hemisphere)
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
A syndrome in which people ignore objects located toward
their left and ignore the left sides of objects located
anywhere
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2 major symptoms:

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Neglect of the left halves of things in the environment
Neglect of the left half of one’s own body
 People
with unilateral neglect can see things to the left
and can tell when someone touches their left side, but
they normally ignore it; not normally conscious of them
 Most
often caused by damage to the right parietal lobe
 Rare
cases of unilateral right neglect – damage to left PL
(PL)


Slight, difficult to detect, temporary
Why?
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Parietal lobe
 Receives
information directly from skin, muscles, joints
and the internal organs, and the part of the inner ear
concerned with balance
 Concerned
 Also
 Its
with the body and its position
receives auditory and visual information
most important function - put together information
about the movements and location of the parts of the
body with the location of objects in space around us
Hemispatial neglect
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Visual Neglect
 Neglect
patients may also ignore the
contralesional side of their body, shaving or
adding make-up only to the non-neglected
side.
 Neglect
may also present as a delusional
form, where the patient denies ownership
of a limb or an entire side of the body.
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Ramachandran video: Secrets of the
Mind
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Phantom limb
 The
sensation that an amputated limb is still
attached to the body
 Map of the body in the somatosensory cortex
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Homunculus
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Homunculus
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Phantom limb
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Sensations experienced are often painful
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Mirror box
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Provided visual feedback for phantom limb
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Ramachandran video: Secrets of the
Mind
 Capgras
A
Syndrome (or Capgras delusion)
disorder in which a person holds a delusion
that a friend, spouse, parent or other close family
member has been replaced by an identicallooking imposter
 Disconnection of visual information from emotion
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Summary
 As
pointed out by Ramachandran and Carlson,
studies of people with brain damage provide
some insights, even though we do not know
much about the physiology of consciousness
 Consciousness
seems to involve operations of
the verbal mechanisms of the left hemisphere
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The Nature of Physiological Psychology
 The
field of physiological psychology grew out of
psychology
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First textbook of psychology was written in 1874 by Wilhem
Wundt and was titled Principles of Physiological Psychology
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The Nature of Physiological Psychology
 What
is the ultimate function of the nervous
system?
 BEHAVIOR
 Physiological
psychologists work with biologists,
physiologists, and other neuroscientists to explain
behavior
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The Goals of Research
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The goal of all scientists is to explain the phenomena they study

Two types of scientific explanations:

Generalization – a general conclusion based on many observations
of similar phenomena.

Reduction – a phenomenon is described in terms of the more
elementary processes that underlie it.
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Biological Roots of Physiological
Psychology
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Hippocrates (460-370
B.C.)

Considered the brain to
be the center of thought
and emotions.

Many ancient
philosophers assigned
this role to the heart
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Biological Roots of Physiological
Psychology
René Descartes (17th century)

Philosopher and mathematician
(Father of Modern Philosophy)
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Reflexes – automatic, stereotyped
movement that is produced as a
direct result of a stimulus.
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Dualism – humans possessed a
mind not subject to the laws of
the universe
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Pineal Body – site of the link
between the mind and the body
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Biological Roots of Physiological
Psychology
Luigi Galvani (17th century)
 Electrical
stimulation of
the nerve in a frog’s leg
produced contraction of
the leg muscle.
 This happened even when
the nerve and muscle were
separated from the rest of
the body
 Brain did not inflate
muscles with fluids
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Biological Roots of Physiological
Psychology
Johannes Muller (1801-1858)
 Advocate of using experimental
techniques, rather than
observation and classification
 Doctrine of Specific Nerve
Energies – because all nerve
fibers carry the same type of
message (i.e., electrical impulse),
sensory information must be
specified by the particular nerve
fibers that are active.
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Biological Roots of Physiological
Psychology
Pierre Flourens
 Experimental
ablation – research
method where the
function of a
particular region of
the brain is inferred
by observing the
behaviors an animal
is no longer able to
perform after that
area is damaged.
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Biological Roots of Physiological
Psychology
Paul Broca
 Extended the concept of
‘experimental ablation’ to
humans.
 In 1861 he performed an autopsy
on the brain of a man who had a
stroke that left him unable to
speak
 Broca’s area – region of the left
hemisphere involved in speaking
ability.
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Biological Roots of Physiological
Psychology
Gustav Fritsch & Eduard Hitzig
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Used electrical stimulation of the
brain to understand function.
Applied weak current to the exposed
surface of a dog’s brain
Observed that stimulation to a
specific region, now known as
primary motor cortex, caused
contractions of muscles on opposite
side of the body
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Biological Roots of Physiological
Psychology
Hermann von Helmholtz (19th century)
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Responsible for developing the law of
conservation of energy, the
ophthalmoscope, a theory of color vision
and blindness
First to attempt to measure the speed of
nerve conduction.
Neural conduction (90 feet/s) slower than
conduction in wires
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Natural Selection and Evolution
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Charles Darwin (1809-1882)
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According to Darwin, all
of an organism’s
characteristics have
functional significance
Principles of natural
selection and evolution
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Functionalism and the Inheritance of
Traits
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Functionalism – the principle that the best way to
understand a biological phenomenon is to try to
understand its useful functions for the organism.

Darwin formulated his theory of evolution to explain how
species acquire adaptive traits – the cornerstone of this
theory is the principle of natural selection
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Natural Selection – process by which inherited traits that confer
a selective advantage become more prevalent in a population.
Mutations – a change in the genetic information
contained in the chromosomes of sperms or eggs,
which can be passed on to an organism’s offspring.
 Selective Advantage – a characteristic of an organism
that permits it to produce more than the average
number of offspring of its species
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Figure 1.12 Bones of the Forelimb
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A) human
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B) bat
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C) whale
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D) dog
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Through the process of natural
selection these bones have
been adapted to suit many
different functions.
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Evolution of the Human Species
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Evolution – a gradual change in the structure and physiology of
plant and animal species, generally producing more complex
organisms, as a result of natural selection.
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New species evolve when organisms develop novel
characteristics that can take advantage of opportunities in the
environment.
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Evolution of Large Brains

The evolution of large brains enabled humans to make tools, build
fire, develop language, etc. that helped them compete with other
species
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In terms of absolute size, the human brain is very small compared to
other animals such as the elephant and whale.
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Proportionally, however, the human brain makes up 2.3% of total
body weight
 elephant
brain - 0.2%
 shrew brain - 3.3%
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Evolution of Large Brains

Critical issue for intellectual ability is not the size of the brain but the
number of neurons available for learning, remembering, and making
plans, as opposed to processing sensory and motor information.

The most important factor responsible for the evolution of the human
brain is a slowing of brain development
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Neoteny – a slowing of the process of maturation, allowing more
time for growth; an important factor in the development of large
brains.
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Please read on your own!
 Ethical
Issues in Neuroscience
 Careers
in Neuroscience