University of Toronto 1
PSYB65: Human Brain and Behavior
Techniques in Neuropsychology:
Investigating How the Brain produces Behavior in Humans
Study of the Damaged Nervous System
The Scientific Method: has at its roots in the principles of objectivity and replication or
confirmation of results
Empirical Method = level of objectivity “observation”
Replication: when neuropsychologists try to replicate their results to prove their findings
were not a fluke.
Control: the ability to manipulate something to determine the effects and cut out
extremes and confounding variables that may cause a researcher to make false
Refers to having an appropriate comparison sample so that deviations from this
sample can be observed
Hypothesis prediction that may be formed as a statement that can be rejected
Independent variable: variables that researcher manipulates to determine how the
behavior is affected
Dependent variable: response or behavior that the experimenter measures
Converging Operations: allows conclusions to be made based on different ways that a
hypothesis is tested.
Nonhuman Animal Models
Non-Human Research: Raising non-human subjects in controlled conditions allows for
less variability between subjects that is not available in human subjects.
Limitations of this are that if the animal performs the task incorrectly would you
attribute it to learning or lack of interaction with the stimulus?
Also, the conclusions may not be generalizable to other species, especially
humans which have much more complex nervous systems.
Non human animals are not sufficiently behaviorally sophisticated to be useful in
understanding the principles of human behavior
Humans have a complex CNS unique too humans, language & memory
Neuropsychological Celebrity: Phineas Gage
25 year old railway construction foreman
Expanding railway – drilling holes, putting in an explosive powder,
inserting a fuse and covering the powder with sand
Phineas accidently prematurely ignited the charge
Explosion projected 4-foot long taming rod through his left cheek,
penetrating the base of his skull and exiting through top of his head
He didn’t’ even lose consciousness – spoke few mins later
Personality has changed dramatically “NEW PERSONALITY”
Focal brain damage can alter one’s personality
1 University of Toronto 2
PSYB65: Human Brain and Behavior
Delayed Nonmatching to Sample task
Tasks involves a food reward and a food-deprived nonhuman animal
Animal observes the food reward paired with stimulus A; then the animal is
required to pick the novel stimulus B to receive the reward
o Researcher discovered many important principles involved in learning
and memory by using such tasks
o Unclear if animals ever exhibit this type of behavior in naturalistic settings
- Mini-mental state exam looks at how people can answer a series of questions,
which are designed briefly to examine cognitive functions such as language,
orientation, attention and orientation to time
- Get a gross degree to which nervous system functions are involved in any injury
Cognitive Testing: these are given to participants in the same way and scored in the
same way so that they are standardized.
They are usually general and if something wrong is detected the test is more
specific, used to help with diagnosis and rehab.
Some limitations occur with this testing since there is a lot of variation in the
population ex. A person with a disability will produce an invalid intelligence test
Functional neuroimaging provides the researcher with in vivo (live) pictures of the brain
areas that are most active during a cognitive task
Structural Imaging: a test that provides an image of the brain structure, which helps
clinicians find the location of an injury or abnormality.
Discovered when a scientist noticed a glowing fluorescent screen on a table
when studying cathode rays.
It was discovered that the rays could penetrate the tube they were contained in.
X-rays – more dense the material, the less penetrable the substance is to x-rays
However X-rays cannot pass through all objects, which are why it passes through
soft tissues or bone cracks, but not dense bone or foreign objects.
The X-rays that pass through are able to hit a photographic plate.
Since X-rays are radiation too much can be harmful, but it can be used to kill
Very dense structures (such as bone) appear bright and lower-density structures
(crack in a bone) appear dark
Provide a 2-D representation of density
These cannot provide information on pathologies inside the skull since the brain
is soft tissue.
o Not proved to be very useful for neuroimaging b/c brain is soft tissue
encased in bone
2 University of Toronto 3
PSYB65: Human Brain and Behavior
o Doesn’t give info on what occurred inside the skull
o Relatively inexpensive and are fast way to get good structural info about
the integrity of the skull, their ability to image the structures within the
skull is limited
Computed Axial Tomography (CAT/CT scans):
Give a non-invasive view of the brain involving computing and x-rays.
It involves sending X-rays into the body at different angles then computed into a
3-D image and brain slices where dense areas are bright and the rest is dark.
The problem is it cannot differentiate between white and grey matter.
The axial version scans in one plane images constructed in one plane
Now CT images can often be constructed in two or other planes as well
Coronal plane shows slices perpendicular to the horizon, taken along the
Sagittal plane perpendicular to the horizon, but taken along the dorsal-ventral
Painless takes relatively little time – performed on an unconscious individual
These scans help identify abnormalities in the brain shown by changes in density
on the scan (except for tumors similar in density to normal cells) so they could be
related to behavioral defects.
Magnetic Resonance Imaging (MRI):
- Noble prize-winning research of Felix Bloch and Edward Purcell
- Produced an image using nuclear magnetic precision measurement, similar to
CT scans, however they have better resolution.
- Initially called “nuclear magnetic resonance imaging” but term nuclear was
dropped from name b/c many people find references to radiation unsettling
o Since hydrogen is a common element in the body with poles facing
random directions, this scan places a strong magnetic field near the brain
so the atoms poles become aligned and polarized.
o Once aligned, atoms can be perturbed in a uniform direction through the
application of a radio frequency pulse
o The machine measures the relaxation time, which follows the pulse,
which is the time taken by the atoms to return to their normal, random
o The receiver coil (measures intensity) and gradient field produce the 3-
o Measured longitudinally (T1) and horizontally (T2), or time it takes for the
atoms to return to their normal positions therefore measures H density.
o The T1 image shows brain, bone, air and water as dark and the T2 shows
a dark image with fluid as bright.
o MRIs contain extremely strong magnets- magnetic strength can be
measured in units of Tesla (T)
o The limitations are that any internal metal in the body will be attracted to
the magnet, which is a dangerous in