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Human Neuropsychology (486 / 686)
Lecture Chapter 1
“The Development of
Neuropsychology”
.
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Overview
-
What is Neuropsychology?
Human Brain
Divisions of the Nervous System
The Brain Hypothesis
The Neuron Hypothesis
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What is Neuropsychology?

Neuropsychology
- Scientific study of the relationship between
behavior and the brain
- Draws from many disciplines, including
anatomy, biology, pharmacology, and
philosophy
- Experimental results from neuropsychological
investigations can be used to identify
traumatic brain injury impairments and vice
versa
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What is Neuropsychology?
Two ideas that influence experimental and
theoretical investigations of brain function
The Brain Hypothesis:
-The brain is the source of behavior
The Neuron Hypothesis:
- The unit of brain structure and
function is the neuron
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The Human Brain

What is the brain?
Brain = Old English word for tissue inside the
skull
Inner hollow tube filled with cerebrospinal fluid
(CSF)
Outer layer of wrinkled tissue known as cerebral
cortex
Composed of two symmetrical hemispheres,
the right hemisphere and the left hemisphere
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The Human Brain

Three Major Divisions of CNS
Forebrain
Cerebral Cortex
Performs higher functions like thinking, perception and
planning
Brainstem
Underlying tube
Performs regulatory and movement producing functions
Spinal Cord
Connected to brainstem and descends down the back
Performs regulatory and movement producing functions
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Features of the Cortex
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Features of the Cortex

Gyri
Folds of the cortex

Sucli
Creases between the
folds
* Large sulci = fissures

Four Lobes:
- Frontal
- Temporal
- Parietal
- Occipital
Examples: Longitudinal
Fissure and Lateral
Fissure
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Divisions of the
Human Nervous System
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The Brain Hypothesis

What is behavior?
“Patterns in time”
Movement of an organism
- cause & function (purposeful?)
- complexity & flexibility

How is behavior produced? Brain vs Heart
Brain Hypothesis - Alcmaeon of Croton
Cardiac Hypothesis - Empedocles of Acragas
Current neuropsychology accepts the brain
hypothesis
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Perspectives on Brain and
Behavior





Aristotle* and Mind
Descartes* and
Dualism
Descartes’s Legacy
Darwin* and
Materialism
Darwin’s Legacy
Natural selection

Linking Brain
Function to Brain
Disease
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Donald Hebb:
“Modern psychology takes completely for granted
that behavior and neural function are completely
correlated, that one is completely caused by the
other. There is no separate soul or life force to stick a
finger into the brain now and then and make neural
cells do what they would not otherwise. It is quite
conceivable that some day the assumption will have
to be rejected. But it is important also to see that we
have not reached that day yet: the working
assumption is a necessary one, and there is no real
evidence to oppose it. One cannot logically be a
determinist in physics and chemistry and biology, and
a mystic in psychology.”
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Experimental Approaches to Brain
Function

Localization of
Function - different
parts of the brain
perform different
functions
-
Franz Josef Gall and
Johann Casper
Spurzheim
• Phrenology
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Phrenology

Problems
Impossible to define and quantify objectively
Features of the skull reveal little about the brain

Historical Importance
Laid foundation for modern localization of
function
Phrenological map was the precursor for many
maps of the brain
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Localization and Lateralization of
Language

Paul Broca*
-
Broca’s Area: anterior speech region of the brain
Lateralization: Functions can be localized to one side
of the brain
Tan’s Lesion
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Sequential
Programming
and
Disconnection

Carl Wernicke*
- Aphasic patients
different from
Broca’s
- Wernicke’s Area
- Posterior
speech region,
located in the
temporal lobe
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Sequential Programming and
Disconnection

Importance of Wernicke’s model
Identified disconnection syndromes
Regions of the brain have different functions but
still must interact to work correctly
Identified the left hemisphere as dominant for
language
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Loss and Recovery of Function

Pierre Flourens
Removed areas of the cortex of
animal brains and studied resulting
changes in behavior
Findings
No specialization for areas of the cortex
Specialization for the brainstem
Findings refuted localization of function
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Hierarchical Organization and
Distributed Systems in the Brain

Hierarchical Organization
John Hughlings-Jackson*
Each successively higher level of
the nervous system controls more
complex aspects of behavior
Dissolution
Reverse of evolution
Occurs after damage to a higher level
Behavior becomes more simple
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The Binding Problem

H.M. (Henry Molaison)

The brain analyzes sensory events through multiple channels,
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yet we have a unified perception of our experiences
The Split Brain

1960s
Neurosurgeons began cutting the corpus
callosum to prevent the spread of seizures

Roger Sperry
Conducted neuropsychological evaluations on
“split brain” patients to discover how the right
and left hemispheres function
Nobel prize in 1981
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Conscious and Unconscious
Neural Streams

The case of D.F.
Visual form agnosia
Inability to recognize objects by their shapes or see
the shape of an object
Able to accurately reach for an object

Optic Ataxia
Can identify the shape of an object
Cannot accurately reach for an object
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Neural Streams
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The Neuron Hypothesis
• The unit of brain structure and function is
the neuron
- Neurons are discrete
- Neurons send an electrical signal
- Neurons communicate with each other via
a chemical signal, or a neurotransmitter
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Identifying the Neuron

Camillo Golgi*
Proposed the
Nerve Net
Hypothesis

Santiago
Ramón y Cajal*
Proposed that
neurons were
discrete
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Nervous System
Cells
Neurons
Acquire information, process
information, and act on
information
Major parts include the cell
body, dendrites, and axons
Glia
Help neurons, hold them
together
Carry out supportive
functions
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Relating Electrical Activity in
Neurons to Behavior

Luigi Galvani
Discovered electrical
stimulation caused
muscular contraction

Gustav Theodor Fristch
and Eduard Hitzig
Electrical stimulation of the
cortex in the rabbit and
dog to induce movement
Discovered topographic
organization in the cortex
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Relating Electrical Activity in
Neurons to Behavior

Roberts Bartholow
First to report electrical
stimulation of human cortex
in a conscious person

Modern Approach
Transcranial magnetic
stimulation (TMS)
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Connections Between Neurons As
the Basis of Learning

Alan Hodgkin and Andrew Huxley
Nobel prize in 1963 for discovery of the
electrical signals generated by neurons

Charles Scott Sherrington
First description of the synapse

Otto Loewi
Discovered that chemicals carry the message
across the synapse
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Connections Between Neurons As
the Basis of Learning

Donald Hebb*
When cells are activated at the
same time they establish or
strengthen the synapse
Hebb or plastic synapses
The brain is plastic and
constantly changing
 There is ongoing
reorganization

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