COGNITIVE NEUROPSYCHOLOGY
LECTURE 1 INTRODUCTION
Why cognitive neuropsychology?
Descartes says that inputs are passed on by the brain sensory organs to the pineal gland in the brain
and from there to the immaterial spirit.
Gall introduced the idea of localization of function, just like the organs (phrenology).
Broca found evidence for localization.
Take home messages in the book.
We do not directly perceive the world, but rather interpret incoming information. E.g., color blindness,
the visual information is the same, but how different people interpret it is different. The same with
auditory information, e.g., soesjes/sushi. Mental processing as an information processing problem: (1)
information processing depends on pre-existing internal representations (beliefs, concepts, desires,
perceptions), and (2) these mental representations undergo transformations.
Cognitive psychology uses behavioral experiments to find out what these representations and
transformations are.
Case study: memory comparison task
Measures if we process parallel or serial.
Research provide insight into mental transformations/how information is processed.
Stroop task
Limitations in information processing also inform us about mental transformations.
In the Stroop task you have to name the color of the ink. The incongruent Stroop condition shows: (1)
2 representations are activated, and (2) ‘word’ representations is dominant at least when reporting
verbally.
Cognitive psychology uses behavioral tasks to study mental representations and transformations. It is
useful to understand mental processes and their limitations. Limitations cannot probe anything that is
not expressed in behavior, and they do not give insight in how these processes are implemented in the
brain.
Tasks often have many components: what components leads to the disability in the patient?
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Double association: a research process for demonstrating the action of two separable separable
psychological or biological systems, such as differentiating between types of memory or the function
of brain areas. One experimental variable is found to affect one of the systems, whereas a second
variable affects the other. Familiarity memory has something to do with temporal lobe lesions and
recency memory has something to do with frontal lobe lesions. If a part of the brain is important for a
particular function, this function will deteriorate after damage to this region.
Lesion and imaging studies complement each other. Lesion studies show certain brain areas are not
necessary and that the brain found its way around this region to function. And imaging studies show
how the ‘normal’ brain works without lesions.
Patient lesion studies tell us what regions are necessary, but not how a ‘normal’ brain works. A
limitation is the compensation mechanisms.
Case study
Relation PTSD and bran size of the hippocampus. This is a twin study where one twin goes in to
combat and the other one is not.
Interventions to assume causality
Lesion surgery: (1) frontal lobotomy, (2) split brain (epilepsy), and (3) epilepsy source removal.
Brain stimulation: (1) patients; DBS and ECT, and (2) healthy; transcranial magnetic stimulation,
focused ultrasound stimulation, and TACS.
Psychopharmacology: giving medication/drugs.
Summary patient studies
Patient studies can show that a region is necessary. Limitations of patient studies are: (1) double
dissociations are needed to show specificity, (2) compensation mechanisms, (3) exact damage location
may vary between patients, (4) most patient studies show correlation, not causation, and (5) surgical
intervention in non-healthy patients only.
Transcranial stimulation
Transcranial magnetic stimulation (TMS) generates artificial reversible ‘lesions’ or activations and
disturbs cognitive processes. TMS has high temporal precision.
Advantages of TMS are: (1) subject is their own control, (2) safe and non-invasive, and (3) in healthy
brains. Limitations of TMS are: (1) only superficial cortex, (2) spatially non-specific, and (3)
up/downstream effects.
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The brain can be manipulated via pharmacology. Communication between neurons depends on
neurotransmitters and these neurotransmitters are related to many psychiatric disorders. Medication
can manipulate the neuro chemistry (neurotransmitters). Limitations of using pharmacology: (1)
regional specificity, (2) temporal specificity, and (3) drug specificity.
The aim of functional neuroimaging is to find neural correlations of cognitive processes.
Functional magnetic resonance imaging (fMRI) is based on oxygen rich and poor blood which differ
in magnetic properties. The blood oxygenation level dependent (BOLD) signal is measured.
Single cell recordings are mostly done in animals. They are very temporally and spatially specific, but
limited to only a few neurons.
LECTURE 2 SENSATION AND PERCEPTION, OBJECT RECOGNITION
Light enters through the cornea and activates the receptor cells of the retina located along the rear
surface. There are two types of receptor cells: (1) rodes, and (2) cones. The output of the receptor cells
is processed in the middle layer of the retina and then layer of the retina and then relayed to the central
nervous system via the optic nerve, the axons of the ganglion cells.
Spectral sensitivity functions for rodes and the three
types of cones: the short-wavelength (blue) cones are
maximally responsive to light with a wavelength of
430 nm. The peak sensitivities of the medium-
wavelength (green) and long-wavelength (red) cones
are shifted to longer wavelengths. White light such as
daylight activates all three types of receptors because it
contains all wavelengths.
The ventral and dorsal pathways: the projections from V1 to higher areas in the cortex can be roughly
divided into two major parallel pathways: (1) a ventral pathway, leading from V1 to the temporal lobe
that is important for representing “what” objects are, and (2) a dorsal pathway leading from V1 to the
parietal lobe that is important for representing “where” things are.
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The type of blindness depends on the lesion in
the brain. When there is a lesion in the primary
visual cortex (V1), patients might still respond
to stimuli in the blind field (blindsight).
The visual system (cortical pathways):
The retina is via the superior colliculus connected to the amygdala, responding to emotion. According
to research, people blinded by brain damage can respond to emotive expression. Subjects responded
(pupil response) to images of happy or fearful body postures and facial expressions. Even though they
were not aware of what they were seeing, so there was no different in seen and unseen in the patient.
Patients are most of the time not aware of the body postures. One area known to receive visual
information independently of the visual cortex is the amygdala, the brain’s emotional control center.
