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Chapter 3

PSYB65 - Chapter 3 - Sep 27, 2010-Oct 4, 2010

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Ted Petit

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Chapter 3 Techniques in Neuropsychology:
Investigating How the Brain Produces Behaviour in Humans
Module 3.1: Study of the Damaged Nervous System
The Scientific Mind
-Empirical method (empirical meansobservation”) – the way scientists gather information,
using standardized tests or measurements with a high level of objectivity.
-Principle of Control – ability to manipulate something of interest to determine the effects
Includes the ability to exclude unwanted variables from the study
Refers to having an appropriate comparison sample, so that deviations from this sample
can be observed.
-Hypothesis – prediction; formed as a statement that can be rejected.
Help to avoid questions that cannot be disproved
-Independent variables – to determine how the behaviour is affected
-Dependent variables – the response or behaviour that the experimenter measures (should be
directly related to the manipulation of independent variable)
-Much of the research in neuropsychology is only quasi-experimental.
(ethically and practically, we cannot manipulate the independent variable directly)
-Converging operations – the use of a number of studies that approach the question from a
variety of perspectives, and the examination of the results to support a common conclusion.
Nonhuman Animal Models
-Provides important information about psychological constructs, e.g. learning, memory and
-Delayed nonmatching to sample task – the animal observes the food reward paired with
stimulus A; then the animal is required to pick the novel stimulus B to receive the reward.
(Involves food reward and food-deprived nonhuman animal)
Summary of the Strengths and Limitations of Nonhuman Animal Research
Strengths Limitations
Can control extraneous variablesSome topics may not be suitable
Can perform experiments There are striking differences between human
and nonhuman nervous systems
Can conclude causalityMight study one behaviour/brain area in
Can look for mechanisms in a simpler systemMight be very artificial
Can model disease processesHuman brain has functional diversity
Cognitive Testing
-Standardized cognitive tests are standardized in two ways:
1. Always given to participants in the same way
2. Always scored in the same manner
(E.g. if a person were to be given the same test byb two different neuropsychologists, that
person should receive the same score on both tests and should not notice any deviation in how
the test was delivered. – however, there are always small differences)
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Module 3.2: Brain Imaging
Structural Imaging
-Provides an image of the structure of the brain
The precise location of abnormalities
X-rays (useful for medical imaging)
-Rays capable of penetrating solid materials, including wood, metal, and human tissue.
Describes the nature of the entry wound
Can be used therapeutically to destroy unwanted tissues, such as cancerous growth.
Useful when looking for bone fractures
Cannot differentiate between cerebrospinal fluid and brain structures very well
-Neuroradiology – studying the nervous system with imaging
-The more dense the material, the less penetrable the substances is to X-rays.
Computed tomography (CT)
-A means of imaging live brain tissue that combines X-ray technology with computing.
Involves the projection of X-rays from multiple angels followed by the computerized
reconstruction of the measures into three-dimensional (3-D) images.
Provides measurement of densities of various tissues (differentiation between white and
gray matter is rather poor)
Can be performed on an unconscious individual
-Computed axial tomography (CAT)
Axial refers to images being constructed in one plane, the axial plane (horizontal plane)
Most early CT images were constructed in this plane, but now they are often constructed
in two other planes as well.
Coronal plane – show slides perpendicular to the horizon, taken along the superior-
inferior axis.
Sagittal plane – perpendicular to the horizon, taken along the dorsal-ventral axis.
-Some brain tumors can have densities very similar to those of the surrounding tissues, making
them difficult to detect on CT scans.
Magnetic resonance imaging (MRI)
-Method for studying tissues using magnetic fields and radio receivers
-When placed in a strong magnetic field, the atoms become aligned – the north poles on all the
atoms point in the same direction. Atoms can be perturbed in a uniform direction through the
application of a radio frequency pulse.
-MRI machine measures the relaxation time, that follows the pulse, which is the time taken by
the atoms to return to their normal, random state. MRIs receiver coil measures the
information about the intensity of the signal, but the spatial information is provided from
variations in the gradient field. (combination of these two types of information allows the
construction of 3-D images of the brain)
Different substances relax at different rates along these dimensions. >> images of T1
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