w1 Flashcards
how do we study cognitive psychology
controlled lab setting
how do we shed light onto cognitive processes
using clever experimental manipulation
what does experimental psychology traditionally not care about
the underlying brain
processes
what does cognitive psychology use instead of brain measures
behavioural measures
like reaction times (RT) or accuracy as
indirect measures
what has cognitive psychology been good at generating
theories about cognition that can
be tested in neuroscience
how has cognitive psychology developed the discipline
made a huge contribution to
making Psychology a more
empirical science
3 issues with cognitive psych
ecological validity, face validity, Do Psychological
concepts even exist?
issue with ecological validity in cognitive psych
Can we generalise
findings outside
the lab?
issue with face validity in cognitive psych
cognitive psych only provides
indirect measures
of cognitive
processes
what does neuropsychology study
cognition in patients with
brain injury
what is the goal of studying cognition in patients in neuropsychology
Goal is to find which cognitive
functions are impaired, and which
ones are preserved when a given
brain region is damaged
3 issues with neuropsychology
no baseline, generalisation, modularity
issue with no baseline in neuropsychology
We don’t
know exactly
what the
patient could
do before their
injury
issue with generalisation in neuropsychology
Lesions in
some areas of
the brain are
relatively
common,
while others
are very rare
issue with modularity in neuropsychology
Cognitive
process X is
likely
distributed
across multiple
areas, not just
one
what does cognitive neuroscience refer to
brain structure and brain
function to cognitive processes
how is cognitive neuroscience typically done
by recording brain
activity while participants perform
cognitive tasks
how many neurones in human brain
~80 billion
neurons
how many neurones may one neurone connect with
10,000
what % of the brain is made up of neurones, and what makes up the rest
Neurons make up only 10% of brain
cells - glia cells comprise rest
lobes of the brain from back to front
frontal lobe, parietal lobe at top, temporal lobe at bottom, occipital lobe as back, cerebellum at bottom
4 ways to study the brain
Electrophysiology (EEG)
Structural Imaging (MRI)
Functional Imaging (fMRI)
Brain stimulation (TMS)
how does electrophysiology/single cell recordings work
Very small electrode records
neural activity from within axon
(intracellular) or from outside
axon membrane (extracellular)
when is electrophysiology/ single cell recordings used
usually only animals, sometimes we have the rare
chance of recording from
patients with epilepsy
how does EEG work
measures electrical activity of a large number of neurons all firing
together, recorded via electrodes on the scalp
what does EEG allow us to do
measure neural activity in essentially real-time
(millisecond scale)
how does ERP work
Measure EEG response to the same
stimulus/task over and over
Average waveform to generate an
“event-related potential” (ERP)
Just like averaging reaction times to
get a cleaner estimate of the “true”
effect
advantages of EEGs/ERPs
Very good temporal resolution (milliseconds)
– i.e. when something happens
Portable and relatively cheap
problems with EEGs/ERPs
Poor spatial resolution (centimetres)
– i.e. where in the brain it happens
– There are an infinite number of possible origins for any signal recorded at the scalp, so we need solid computational models to make
an informed guess
magnetic field of MRI
0.5 – 7 Tesla (T)
how does MRI work
Single protons in water molecules (A) tend to align to the powerful
and stable magnetic field generated by the scanner (B))
We then disturb this alignment with short radio-frequency pulses
and measure the resulting change in magnetic field (C)
Different parts of the brain (grey matter, white matter, CSF) take different times to “relax” from the radio frequency
disturbance, and show as lighter/darker
how does diffusion tensor imaging (DTI) work
DTI can image white matter fibres (bundles of axons) by
measuring the direction of water diffusion
what does DTI allow us to do
study how cognition/perception is supported by connections between brain regions
what does FMRI measure
BOLD = Blood
Oxygenation Level Dependent signal
what does FMRI measuring BOLD signal indicate
Active neurons need oxygen
– The brain starts supplying oxygen to
active areas, producing an
“overshoot” in oxygenated blood
– Oxygenated blood causes less
magnetic field disturbance than
deoxygenated blood, so active brain
regions will have higher signal
pros of FMRI
Very good spatial resolution
(millimetres)
* i.e. where something happens
cons of FMRI
Poor temporal resolution (seconds)
* i.e. when it happens
* Not a measure of neurons
themselves!
* Requires an indirect inference
that neurons are firing because
that part of the brain is using
more oxygen
MRI, EEG, ERP provide correlational evidence, what can provide causal evidence?
Brain stimulation
techniques
what is trans cranial magnetic stimulation (TMS)
- Short magnetic pulses that briefly
affect electrical activity in a localised
patch of brain tissue under the coil - Is typically applied either before or
during a cognitive task - Can have positive or negative effects
on task performance
TMS pros
Causal evidence that a particular brain
region is important for a cognitive function
* Not just correlational, like brain imaging
– Mostly non-invasive
* i.e. safe and painless for healthy
populations
TMS cons
Stimulation to the brain is very weak as it
happens from outside of the head
* Therefore, the effects are often weak
– Potential risk to individuals with history of
epilepsy
3 cognitive neuroscience limitations
expensive/ invasive, theories, does it help us understand cognition?
expensive/ invasive issue in cognitive neuroscience
Worth the expense?
* Often means that
sample sizes are
small
* Generalisable?
issue with theories cognitive neuroscience
Emphasis in the
literature on
measuring brain
effects rather than
testing theories
issues with understanding cognition in cognitive neuroscience
What does it mean
to understand?
what do we learn from optical illusions?
The brain doesn’t see at all.
*It receives electrical signals
about how light interacts
with the eye, and then it
must infer what is out there
in the world.
what has a strong influence on perception
top-down processes
how do mental/cognitive processes have limits
our brain’s resources are finite and need to be distributed
what is cognitive psychology
the scientific study of
thought and experience
how does an information processing approach view humans
stimulus response
machines
how does info come in according to information processing approach
comes in through
the senses
what happens after info comes in through the senses
It is processed by a series of
modules that change the
information in a systematic way
what is serial processing
only one step at a time
what is bottom-up processing
all processes are directly triggered by the stimulus
what is a criticism of the information processing approach
- Does not allow for parallel
processing - Ignores top-down
processing, i.e. influences
of an individual’s prior
knowledge, goals, and
expectations - Oversimplification!
what are grandmother cells
neurons which have “preferred” stimuli
what is rate coding
greater rate of a neuron’s response is used to code/represent information
what is temporal coding
greater synchrony of the responses of
several neurons is used to code information
