Why study this? Flashcards
What is functional localisation?
Mapping functions to brain areas
What is the task of cognitive psychology?
To provide a taxonomy of human mental life I.e. to break behaviour down into its components
What does PET stand for?
Positron emission tomography
What was the first brain imaging experiment? Who conducted it?
Participants were required to perform complex arithmetic whilst lying on a see-saw. The angle of the see-saw was manipulated e.g. so that blood rushed to their brains or not. Mosso
Why are PET and fMRI not direct imaging techniques? How does PET work?
Because neural activity is not measured, instead a factor which is correlated with neural activity is measured. A radioactive isotope is injected into the participant, then electrodes are fired at the participant and those which collide with the isotope emit the measured positron. Regional cerebral blood flow is inferred
Which has worse temporal resolution: PET or fMRI?
PET
What are the 3 typical features of a BOLD response graph of image number against relative signal? Typically how many seconds lie between the resting and peak signal?
The initial dip (oxygen uptake), overcompensation (increase in the blood’s oxygenation) followed by the undershoot (depletion of blood oxygen levels). 6
Name and describe a founding principle of cognitive psychology. What is the neural equivalent in cognitive neuroscience?
Cognitive subtraction = the comparison of performance under 2 or more matched conditions. Neural subtraction = attributing an info processing difference to a neural processing difference e.g. an increase in RTs to the operation of and switching between 2 mechanisms = pure insertion
How has the purpose of cognitive neuroscience changed?
Initially it was used to validate what we already knew from SUR studies and neuropsychological lesion studies. Then it was used to arrive at novel and surprising findings e.g. (given HM) that PFC rather than hippocampus activation predicted LTM encoding success
What problem do SUR studies face?
The inability to attribute a function to the global, neural area
Science has reported neural correlates of…. Then people realised that…
Paying your taxes, schadenfreude, dread and charitable donations. Mapping functions to brain areas was not in and of itself useful and that therefore the traditional approach of building specific, incremental H1s was more useful
Neural imaging has promoted neophrenology or blobology. Why?
Because it looks appealing. Results presented in brain map format were deemed more internally coherent than the same results presented in bar chart format (McCabe and Castle, 2008)
A p value should be corrected according to the number of independent observations made. Is this possible using neuroimaging techniques? So what is the solution?
No, because we don’t know how many voxels in the brain scan are independent. Therefore, scientists simply use a generally more stringent significance level
Bennett (2012) criticises the lack of proper statistical corrections in multiple comparisons. How does he demonstrate his point?
By finding activation of a particular brain area when a dead salmon views a situation from different perspectives
How can the problem of multiple comparisons be avoided?
By making predictions a priori regarding the brain region of interest in terms of activity levels
What is statistical circularity or double dipping?
Changing a priori predictions regarding the brain region of interest in light of the data
What is the sin of reverse inference? Why is it a sin?
Using known functions of specific brain areas to infer how a participant is performing a task. Because one brain area can be activated for multiple reasons I.e. there is no one-to-one brain-function mapping
Brain imaging is a correlational rather than causal inference technique. Therefore, activations may be ___ to the task, especially in ___ ___ experiments in which…because then you do not have tight control over what the participant is doing with the stimuli
Incidental, passive viewing. People are not required to actively process the stimuli seen
E.g. If brain area X is more active for faces than phones…
That may be because faces have expressions, eyes, relationships, familiarity etc which phones don’t have but you don’t know which feature increased activity, hence the control and experimental conditions should differ by only 1 V
According to Pashler and Harris (2012), 56% of all findings are false. This is based on…
Our detection power = our ability to find an effect where one exists & the % of H1s which we set out to test which are true
If it’s too difficult to discover how the brain works, we can at least discover…e.g….
What format the answer to ‘how does the brain work?’ takes e.g. do we want a description of all cell types and their functions and locations? Or do we want a description of all cell connection types and their functions and locations?
Two realistic questions for research on the brain are:
By what principles does the brain convert inputs into outputs? How can we best classify elements of the system which is the brain?
Name 3 routes of research used to classify brain elements
Identifying differences in cytoarchitecture (cell types and arrangements), identifying connections between areas e.g. tractography divides the brain into parts connected to similar places, identifying correlations between areas’ activity levels at rest (resting state correlations)
We would like to know about 2 types of properties of elements of the brain as a system. What are they?
1) representational properties: what types of inputs do elements respond to/ represent?
2) computational properties: how does information flow through the elements? E.g. EEG and MEG tell us about the temporal properties and order of info flow
How do single and multiple unit activity recordings work?
Single or multiple electrodes are placed in extracellular space to record spikes from individual neurons in awake or anaesthesised animals
What is an advantage and disadvantage of SUR or MUR?
We can record from individual neurons. The function of the global region cannot be inferred from max a few hundred neurons
At the univariate level there may be no difference in the overall activity recorded from a brain area under 2 conditions (e.g. a grating at…) due to limitations on ___ ___. Multivariate voxel analysis overcomes this issue by…
Spatial resolution. - or + 45 degrees. Identifying distinct patterns of activity associated with classes of stimuli
Why is computational neuroscience important for identifying latent variables? How does it work? E.g.
Because latent variables are not present in the inputs or outputs to the brain. It works by predicting the presence of a mechanism in the brain, which is then supported by neural findings e.g. prediction errors & the dopaminergic neurons’ corresponding firing rates
The ultimate use of imaging rather than mapping function to locations is to…This requires a move away from merely ___ imaging
validate predictions regarding the mechanisms and organisation of cognition. Descriptive
