NP I
Introduction to Neuropsychology
Neuropsychology: Neuropsychologists are clinicians with knowledge of
neuropsychological symptoms and test methods to carry out the
diagnosis and treatment of patients with brain disorders (or damage
because of age or accident)
- They study the relationships between (physical) brain functions
and behavior (in specific behavior, emotions, and cognition)
Fields:
- Clinically oriented: Clinically oriented neuropsychology research
involves studying the relationship between brain function and
behavior in individuals
with various
neurological or
psychiatric conditions
o Helping through
assessment
(empirical cycle)
o Standard tests
are often better
than experimental tasks
Due to standard tests being comparable with other
studies or experimental being insufficiently clear
o Limitations:
Conclusion is largely dependent on quality of tests and
questionnaires used (validity problem)
Solution: Experimental research paradigms
(more control)
Test battery (group/set of several tests to obtain a
comprehensive assessment) can only contain a limited
number of tests
Missing values, due to the patient not completing the
test battery
- Fundamental oriented: Aims to advance our theoretical
understanding of brain function and its relationship to behavior
o Experimental paradigms: Fundamentally oriented
neuropsychology research often involves designing and
conducting experiments to manipulate specific cognitive
processes or neural circuits in animal models or human
participants
Neuro-myths: A misconception generated by a misunderstanding, or a
misreading, or a misquoting of facts scientifically established (by brain
research) to make a case for the use of brain research in education or
other contexts
, - Neuromyths often originate from overgeneralization of empirical
research, and are reinforced/propagated
Subtraction method
- Franciscus (Frans) Cornelis Donders (1818-1889)
o Mental chronometry:
Reaction time paradigm = The use of reaction times
to evaluate
cognitive processes
By
subtracting
the Simple
task from
the Go/no-
go task, we
know how
long discrimination took for the participant (and
the subtracting of the Go/no-go task from the
Discrimination/Choice task for selection)
Pure insertions = A single cognitive process can be
inserted into a task without affecting the duration of
other processes
- Criticism:
o Fallacies of pure insertion
Potential other mental processes involved in tasks
Solution: Include multiple tasks/contrasts
o Limited ecological validity
Gap between test and everyday behavior
Solution: Add questionnaires & observations
Or virtual/augmented reality (which can help
standardize the environment)
Dissociation (not dissociative disorder!)
Dissociation demonstrates that sub-processes are independent of each
other, as each of them can be disrupted separately
Goal: To identify the neural substrate of a particular brain function and/or
on the localization of function using care studies, neuroimaging and/or
neuropsychological testing (relates to the selective loss of a function)
- Single dissociation: Difference
between tasks due to brain lesion
which must be associated with the
aspect of behavior studied
, o Assumes a serial organization of function in the brain
- Double dissociation: Demonstrates that two (more or less)
independent cognitive processes rely on different brain regions or
mechanisms
o However, a single neural
network model can also
show patterns of double
dissociation, meaning that a
pattern of double
dissociation in two patients
does not necessarily
indicate independent modules
Statistical tests necessary to ascertain whether the patient’s
performance does indeed deviate from or fall within the normal range (+/-
2SD)
- Interpretation of dissociation:
o Scores on one task should significantly fall above or below the
average of the normative group
o AND the differences between the performances on task A and
B differ significantly from each other
- Be aware of test-retest effect (when testing a patient after
damage and after their recovery, they might perform better at the
test due to practice effect, they have done it before so they are
familiar and thus better at it)
Neuroimaging
Spatial resolution: Sharpness of the image
Temporal resolution: Speed of the recording
Voxels: The pixel of neuroimages, and their grey value is related to a
certain type of tissue
- CT:
o Relatively high resolution
o Able to produce different ‘slices’ of the brain in several
angles (e.g.,
sagittal,
transverse,
or coronal)
o Able to
identify
abnormalities in the brain (e.g., hemorrhage, lesion, or
tumor)
- MRI:
, o High resolution
o Clearer image of soft tissue compared to CT: MRI can
distinguish between grey matter and white matter (but way
more expensive than CT)
o Able to identify abnormalities in the brain (e.g., hemorrhage,
lesion, or tumor)
- fMRI:
o Register moments of activity of the magnetic protons in the
body
o Increased activity in a
certain area in the brain is
associated with increased
blood supply in these brain
areas
o Measures ration between
oxygen-rich and oxygen-
poor hemoglobin (BOLD =
Blood Oxygenation Level
Dependent)
Due to there being a
dip in the oxygenated
Hb, the body knows there is more blood needed in that
area and it will peak in oxygenated Hb (this is seen on
the fMRI)
- EEG:
o High temporal resolution
o Measures the
electrical
activity
generated in
the brain cells
(Event Related
Potentials =
ERPs)
- PET:
o Measuring
specific
receptors, to
infer whether certain neurotransmitters systems are
functioning abnormally
