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Chapter 3

PSYB65H3 Chapter Notes - Chapter 3: Laboratory Rat, Scientific Method, Radiography

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Ted Petit

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Chapter 3: Techniques in Neuropsychology
Study of the Damaged Nervous System
The Scientific Method
- The scientific method has its roots in the principles of objectivity (empirical method) and
replication or confirmation of results
- Control: refers to the ability to manipulate something of interest to determine the effects.
This also includes excluding unwanted variables from the study (confounding variables).
Having an appropriate comparison sample is also needed.
- Hypothesis: a statement that can be rejected
- Independent variable: variable manipulated to determine how the behaviour is affected
- Dependant variable: the response or behaviour that the experimenter measures
- Converging operations: a common conclusion is reached by examining a number of studies
that approach the question from a variety of different perspectives
Nonhuman Animal Model
- From 1930 to 1965, much of psychology was dominated by the study of the white laboratory
- It was thought that the study of nonhuman animals would provide important information
about important psychological constructs, such as learning, memory, and emotionality.
- Nonhuman animals raised in controlled conditions reduces the variability that is attributable
to extraneous factors, and this degree of homogeneity allows the experimenter to randomly
assort the subjects into various treatment groups
- There is a great degree of overlap among the basic properties of the nervous system,
including chemical and electrical means of information transfer, metabolism, and even, in a
very general sense, the layout of the nervous system
Cognitive Testing
- Often, a neurological exam includes an exam known as the Mini-Mental State Exam or the
Modified Mini-Mental State Exam
- Behavioural testing: standard testing/scoring procedures, and identifies specific cognitive
Brain Imaging
- Functional Neuroimaging provides the researcher with in vivo (live) pictures of the brain
areas that are most active during a cognitive task
Structural Imaging
- X-rays: high density areas (such as those containing bones) absorb more X-rays, and provide a
2-D representation of density. High levels of X-rays can destroy tissue due to the radiation
Chapter 3: Techniques in Neuropsychology
- Computed Tomography (CT): the first good means available to noninvasively image live brain
tissue. CT scans involve the projection of X-rays from multiple angles followed by the
computerized reconstruction of the measures into 3-D images
- Magnetic Resonance Imaging (MRI): initially called “nuclear magnetic resonance imaging”,
and exploits the fact that many elements (such as hydrogen) can be influenced by magnetic
fields (measures relaxation time that follows the pulse)
Electrophysiological Methods
- Electroencephalogram (EEG): small metal disks are attached to the scalp and the small
changes in electrical potentials are amplified and recorded (measures the “idling brain”)
- Event-Related Potentials (ERPs): to study the brain’s response to stimulation, a stimulus is
presented repeatedly while an EEG is recorded (slow waveform usually emerges during
stimulation and are “event related” or “evoked” responses). The technique is good for
studying relatively fast cognitive processes, such as attention and memory.
- Magnetoencephalography (MEG): unlike EEG and ERP, MEG does not measure the electrical
fields at the scalp, instead, MEG measures the magnetic fields that are generated by the brain.
Its advantage is its temporal resolution for cortical structures towards the outer surface of the
Functional Imaging (as energy demands increase, so does blood flow)
- Regional Cerebral Blood Flow (rCBF): participant must inhale Nitrous Oxide (N2O), which
circulates throughout the brain. Isotopic tracers such as Xenon replaced N2O, allowing for
greater localization of the course of radiation.
- Single Photon Emission Tomography (SPECT): is similar to the rCBF, however it provides the
advantage of involving the tomographic assessment of local changes in blood flow, allowing 3-
D imaging
- Positron Emission Tomography (PET): Provides measures of local blood flow, as well as its use
to study the brain’s utilization of other substances, such as dopamine. Also allows for greater
temporal resolution in imaging changes in blood flow.
- Functional Magnetic Resonance Imaging (fMRI): track local changes in blood flow using MRI
imaging. It does not require exposure to radiation or the injection or inhalation of tracers.