PhD Interview Questions Flashcards

1
Q

Why have you applied to do a PhD in York? What is it about working with Professor Andrews that appeals to you? - (4)

A

I am very keen to do a neuroscience PhD at the University of York as it is renowned for being one of the top 10 universities in the UK and well-known for its world- leading research, housing cutting-edge neuroimaging methods such as 3 Tesla fMRI systems in YNICas well as having the ability to work with many experts in the field of neuroscience research, especially face recognition.

I have developed a deep passion for the field of face recognition as I read a couple of Professor Andrews’s papers on the subject as well as learned about neural basis of face perception in neuroimaging of vision as well as currently helping one of Professor Andrew’s PhD student on a project on face recognition.

I very much enjoy working with him.

I have found him to be very supportive and encouraging. His expertise on face recognition using advanced methods like MVPA aligns with my research interests.

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2
Q

What are some of the papers you read from Professor Andrews and what you found interesting? - (2)

A

The study had a series of experiments where participants identified manipulated averaged images of familiar faces
Images had either shape or texture altered to measure importance of each feature in recognition

Key finding was texture plays a dominant role in recognising faces and participants significantly better at identifying faces with preserved texture even when shape was altered compared to opposite scenario.

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3
Q

What skills and attributes do you have that make you a suitable for PhD in area of research? - (7)

A

Over the years, I have also acquired programming skills using R, MATLAB, which I
used in my undergraduate dissertation to conduct correlational tests and as well as use MATLAB specifically to run the experimental script for dissertation.

I have also a working knowledge of Python which I used during my GCSE and will soon learn Python in second semester in introduction to programming course python used to analyse neuroimagning and behavioural data.

These programming skills are needed for fMRI data analysis.

I have a completed a module called ‘Neuroimaging of Vision’ taught by Professor Andrews. This module covers the brain mechanism including face perception.

In addition, I have also done a module on Principles of Cognitive Neuroscience, in which both Professor Andrews and Hartley wcovers how fMRI works and Professor Hartley convered advanced data analysis methods like intersubject correlation and MVPA.

Both these modules form the foundation of my preparation for the PhD.

As I mentioned, I am already involved in working on a similar project in which I
have gained experience on analysis of behavioural data where I acted as a
second coder and some hands-on experience in fMRI data analysis using FSL.

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4
Q
  1. Can you tell us in simple terms about a research project that you have been involved in – what were you investigating and what did you find? - (6)
A

My final dissertation project at Newcastle University was called ‘Prediction of
Speech-In-Noise Performance Using Non-Speech Stimuli’ under the supervision of
Professor Tim Griffiths.

Speech-in-noise perception is basically how well people can hear speech in
background noise. For example, in a pub how well we can hear a friend wile lot of people are talking in the background (This is also called the cocktail party effect).

Now the question how to measure the speech-in -noise performance? The typical
test use a sample of speech (like a word or sentence) within noise added to it. The
task is to recognize the word/sentence.

The speech content is typically recorded in specific language (e.g. English) and thus
the tests can not be used with participants who are not fluent in that language.

To address this limitation a non-speech stimulus called Figure-Ground was
developed. This stimulus consisted of a pattern of coherent tones , which is the
figure a background of non-coherent tones. After hearing two figure-ground stimuli,
participants were asked if the two patterns were same or different.

We then investigated if the performance on the Figure-Ground stimulus was
correlated with performance on conventional speech -in-noise test. We found that
that this was indeed the case. (Typical correlations around 0.4)

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5
Q
  1. What were the correlation values you find in new test and how did it compare to old tests? - (3)
A
  • We measured speech-in-noise using both sentence and word in noise and a typically hearing test called pure-tone
  • Figure-ground between sentence was 0.40 and word was 0.38
  • Did regression showing figure-ground significantly added 10-20% of variance explained in sentence and word in noise tests more than PTA
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6
Q

What is advantages and practical application of dissertation study? - (2)

A
  • Auditory processing disorder is charactercised by speech in noise difficulty and used as a test than convential speech in noise
  • Used for children who do not possess adult level language proficiency, biliuginal and individuals who are non-native speakers
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7
Q
  1. What is figure-ground? - (2)
A

The SFG stimulus consists of a set of tones of varying frequencies that change randomly and a specific subset of tones that remains the same over time.

The fixed frequencies are perceived as the auditory target amidst the ‘background’ of random variation of frequencies

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8
Q
  1. What is limitations of dissertation? - (5)
A

There are some limitations of the study.

The study only considered individuals with “normal” hearing thresholds and native English speakers.

Therefore our results are not extendable to those have hearing deficits and/or not native English speakers.

The performance of the roving stimulus, in terms of predicting SiN performance, needs to be evaluated on these populations.

The criteria of including only “normal” hearing thresholds participants also led to a exclusion of a large number (10/74) of participants from the data analysis

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9
Q
  1. What is figure like in same or different pattern in figure-ground? - (2)
A
  • Figure is same in same pattern
  • Figure is different to one another in different pattern
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10
Q
  1. What is an issue you would like to address during your PhD? - (14)
A

The main question that I am trying to address is how conceptual knowledge helps in familiar face recognition and where in the brain this knowledge is represented.

Research has shown that familiar and unfamiliar faces are processed differently as familiar faces require less effort in recognition despite changes in appearance and are detected much faster than unfamiliar faces

As we get to know someone we acquire both perceptual information as well as conceptual knowledge of a person – like who they are as a person which both aid in the recognition of familiar faces.

There has been limited research that have tried to answer how conceptual knowledge helps in face recognition and where is it represented in brain but a number of limitations

The main being that the paradigm used lacks ecological validity as static facial stimuli associated with artificial conceptual info like name/occupation, perceptual and conceptual in these paradigms are assumed to be separated which does not happen in real life.

To overcome this limitation, task-free naturalistic paradigms have been developed
where participants are watching a engaging movie in a MRI scanner.

The naturalistic viewing paradigm is nice from the ecological perspective, but the problem is how to separate the conceptual from perceptual.

A recently collected behavioural data using naturalistic paradigm has shown that
conceptual information helps in recognition of faces after a delay period.

In this paradigm, there are two groups of participants.

One group watches a movie in its original order and the other watches a scrambled version of the movie.

The idea is that the Original group will be able to construct a narrative where as the scramble group will not be able to.

After watching the movie, subjects perform a face recognition task to identify actors in the movie. Interestingly, immediately after watching the movie, performance of both the original and scrambled version did not differ indicating that both groups are using perceptual
features for face recognition.

However, after a delay of 4-week, the original group performns better than scrambled indicating use of conceptual knowledge in face recognition after delay.

In this current we will use MVPA and ISC to identify the brain network for conceptual
information representation and how the perceptual and conceptual network interacts
using dynamic causal modelling.

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11
Q
  1. Where do you see yourself doing in 5 years? - (3)
A

In the next five years, I envision myself having completed a PhD gaining expertise in face recognition and working a research lab doing my independent research in this relevant field.

My long-term plan is utilising the knowledge and expertise I have gained from my MSC in CN and PhD in face recognition in University of York is to make a career in research in a laboratory and teaching in a University in the UK or USA.

This PhD program will be a foundation for this aspiration.

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12
Q
  1. Do you have any questions?
A

I don’t have any questions as I have been a masters student at the university of York for some time and I have asked a bunch of questions to Professor Andrews who has been helpful and clarified them.

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13
Q
  1. What is your question about your proposal:
A

‘Using Naturalistic Viewing Paradigm to Explore the Role of Conceptual Knowledge in Face Recognition’

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14
Q
  1. Why is recognizing faces so important?
A

The recognition of familiar faces is fundamental for social interactions. For example, recognizing whether a face is someone you know or a stranger dictates how you are going to interact with them.

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15
Q
  1. What are the differences between familiar and unfamiliar faces?
A

There is a difference between familiar and unfamiliar faces as they require less effort in recognition despite their changes in appearance (Bruce, 1982; Young and Burton, 2019) , are detected faster (Gobbini et al., 2013) are processed more automatically (Jackson and Raymond, 2006) and can held in working memory more accurately (Jackson and Raymond, 2008).

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16
Q
  1. What are some of the behavioural methodologies showing differences of familiar faces? - Gobbini - (4) processed much faster
A

o In an experiment doing continuous flash suppression (CFS) task, participants viewed pairs of rapidly alternating images one containing familiar/unfamiliar face and other a house, one image in each pair rendered invisible through CFS making it unconscious

o Task: Participants reported which image (face or house) they “felt” present, even though they couldn’t consciously see it.

o Finding: Participants were significantly faster at detecting the invisible familiar face compared to the invisible unfamiliar face. This suggests that familiar faces can be processed preconsciously, influencing early stages of visual perception.

o Prioritize detection of personally familiar faces even without conscious awareness

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17
Q
  1. What are the theoretical models behind familiar and unfamiliar face recognition? - (3)
A

Models of face processing suggest that image-invariant representations of familiar faces are constructed and stored over time (Bruce and Young, 1986)

These representations then act as a template to which an incoming face image is matched.

With repeated exposure of face, template of familiar face becomes refined and specific containing consistent facial features leading faster and accurate recognition

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18
Q
  1. What is conceptual information of a face?
A

The conceptual information refers to person-specific details such as what is someone’s name, occupation, what are they like as a person, their personality traits are they introverted or extroverted.

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19
Q
  1. What is the perceptual information of a face?
A

The perceptual information of faces is like arraignment of facial features such as eyes, nose, mouth, color of someone’s eyes for example and the shape of the face is it round or someone has a sharp jaw.

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20
Q
  1. What is the evidence showing that perceptual information helps in face recognition? - (2)
A

Studies have shown that the image-invariant representation is derived from experience of face image and its visual features.

For example, repeated experience of the same person’s face from different views, illumination and facial expression produce a robust visual representation (Kramer et al., 2015 study)

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21
Q
  1. Details of Kramer’s study:
A

Kramer et al., 2015 = so participants had faster and more accurate recognition as they saw more images of Jennifer Lawrence as ability to recognise her in novel images from new viewpoints improved

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22
Q
  1. What is the evidence showing that conceptual information helps in face recognition? - (2)
A

Although role of perceptual information in face recognition has received a lot of attention, it has suggested that conceptual information (e.g., name or occupation) associated with face is important for recognition

e.g., Schwartz et al., (2016)

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23
Q
  1. More details of Schwartz et al (2016) study - (3)
A
  • perceptual learning group = saw each face from multiple angles and lighting conditions but received no additional info,
  • conceptual learning group had faces with unique name and occupation,
  • participants took a face recognition with novel images of familiar faces , participants in conceptual performed better than perceptual learning and control in learning faces from new viewpoints
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24
Q
  1. What did Schwartz and Yovel (2019) study demonstrate?
A

More recently, Schwartz and Yovel (2019) showed that the effect of conceptual advantage is not due to modifications of the perceptual representation of faces, indicating that conceptual and perceptual information are encoded distinctly.

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25
Q
  1. More details on Schwartz and Yovel (2019) study on method and findings: - (4)
A

Generally in their methods, they asked participants to rate 20 different identities based on their perceptual appearance and inferred personality traits In learning phase on likert scales e.g., how intelligent the face is.

Then during testing phase images of learned identities differed in lighting and asked to see if the face was new or old to them.

They varied whether participants doing perceptual judgements based on specific facial features e.g, how round the eyes are or globally e.g., how round the face is and found that the conceptual advantage in face recognition is not due to processing the face more globally than part-based or vice versa.

They also showed that participants recognition performance its accuracy was not dependent on taking more time in doing conceptual evaluations (e.g., how intelligent does a face look) of faces than perceptual (e.g., how round a face is) as they measured their reaction times e.g., more elaborative encoding of faces in conceptual.

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26
Q
  1. What do Schwartz and Yovel’s (2019) findings disapprove? - (2)
A

The findings disapprove the Winogrand’s feature elaboration hypothesis that conceptual evaluations take longer than perceptual during encoding as more facial features encoded

Research studies also predict that making conceptual processing involve more global than part-based and the findings disapprove these

27
Q
  1. What is the debate still answered after the paragraph showing conceptual and perceptual knowledge of a person is important
A
  • How perceptual and conceptual information interact in face recognition remains an open question
28
Q
  1. What did Haxby and colleagues propose?
A

They propose a distributed model of face processing that divides brain areas into core and extended network

29
Q
  1. What is core network? - (2)
A

The core network includes includes brain areas such as Fusiform Face Area (FFA), Superior Temporal Sulcus (STS) and occipital face area (OFA), is thought to extract visual features about the face.

Within this network, the STS extracts dynamic features of faces (O’Toole et al., 2002) which change with time (e.g., speech, shifting gaze, expressing emotional expressions), whereas the FFA is involved in extraction of facial features which are invariant (e.g. identity).

30
Q
  1. What is extended network?
A

The role of extended network is to extract ‘higher level’ conceptual information, such as traits and biographical information, associated with the face and includes brain areas such as the anterior temporal lobe (ATL), cingulate and precuneus.

31
Q
  1. What is the role of ATL?
A

ATL = It retrieves sematnci memories related to people we know such as recalling its name, occupation, past experiences etc..

32
Q
  1. What is the role of cingulate?
A

Cingulate involves in recalling emotions associated with person’s face like feelings of trust/empathy

33
Q
  1. What is the role of prenuceus?
A

Precuneus: creates mental representations of situations and past experiences = plays role of retrieving person-specific details through mental imagery and simulation, reconstruct past encounters with specific people and interactions you had with them.

34
Q
  1. What is limitation of previous neuroimaging studies of face recognition? - (2)
A

The limitation of previous neuroimaging studies is that faces are presented in controlled experimental setting that does not reflect our experiences in real life of how we encounter faces

The stimuli Is static and is linked with artificial conceptual knowledge like name and occupation as well as perceptual and conceptual knowledge may not be separately acquired which is assumed in the paradigms as well as facial stimuli is presented in ‘trials’ that are not assumed to be independent of each other.

35
Q
  1. What is naturalistic viewing paradigms? - (2)
A

In these paradigms, participants watch an engaging movie or a documentary while their brain activity is simultaneously acquired in an MRI scanner.

These paradigms first introduced by Hasson et al., 2004

36
Q
  1. How does naturalistic viewing paradigm overcome limitations of static facial stimuli/how does it overcome limitations of previous neuroimaging studies? - (2)
A
  • The facial stimuli are dynamic and not static
  • The movie is more engaging and thus might make participants more cooperative
  • The perceptual and conceptual information is integrated and not separated
  • The conceptual
    knowledge the participants learn of actors in movie is more meaningful as it goes with the story of the movie
37
Q
  1. What is inter-subject correlation (ISC)? - (2)
A

inter-subject correlation (ISC) as a measure to calculate how consistent the activation of a given brain area/voxel is across different participants is when they watch the same movie.

Mathematically, the ISC is simply a correlation coefficient between the time-series of activation extracted from a given voxel/brain area from two participants

38
Q
  1. Why is inter-subject correlation used in naturalistic viewing paradigms - (2)
A

Since the stimuli presentations in these paradigms are not controlled, a challenge lies in the analysis and interpretation of the data.

Hasson et al (Hasson et al., 2004) used inter-subject correlation (ISC) as a measure to calculate how consistent the activation of a given brain area across different participants is when they watch the same movie.

39
Q
  1. What is evidence of inter-subject correlations? - (4)
A

(i) consistent and reliable pattern of activation can be seen in many brain areas (e.g. visual and auditory cortex and ‘higher level’ areas such as precuneus) across different participants while they watch the same movie

(ii) activations of some of these areas were stronger for the natural stimuli and,

(iii) ISC could also distinguish whether the movie was presented forward or backward in time. For example, while visual cortex showed no differences between the forward and backward presentation, higher order areas like temporal parietal junction (TPJ) show weaker ISC in response to backward movie compared to forward movie

(iv) (iv) the ISC can distinguish between the two groups such as a patient and controls:
i. Reduced neural similarity during movie viewing shown in individuals with psychosis or schizophrenia

40
Q
  1. What is the difference between inter and intra subject correlation? - (2)
A

Inter-subject = measures consistency of neural responses across different participants in study

Intra subject = measure consistency of neural responses within same individual across different conditions

41
Q
  1. Why does original group have higher face recognition performance after a delay? (Noad and Andrews) - (2)
A

This is because original group new memories of the identities of the actors are successfully consolidated over delay and their memories of new actors is enhanced as they acquired information of the actors in a coherent context which leads to them having higher face recognition of identities of actors over a longer period.

This is not the case of scrambled group as they watched the movie in scrambled order and their memories of actors they have obtained is not in a coherent context and leads to less stable recognition of them and thus leads to poor performance.

42
Q
  1. What is the aim of your proposal? - (2)
A

However, it remains unclear whether the neural representation that are important for the learning and subsequent recognition of familiar faces are to be found in the core (visual) or extended (conceptual) regions and how the brain areas in the two networks interact when processing familiar faces.

The aim of the current proposal is to address these questions by using advances in experimental paradigm and analysis methods.

43
Q
  1. What is the methodology of your study? - (5)
A

We will use the Life on Mars naturalistic viewing paradigm (see Noad and Andrews, 2023).

However, participants will initially view either the Original or Scrambled version of the movie outside the scanner which they are unfamiliar with. And they are tested on narrative using structured questions of key events of movie and write a detailed narrative.

Participants in both the Original and Scrambled groups will have the same perceptual information but will acquire different conceptual knowledge.

The neural response will then be measured in participants from both groups using fMRI. They will view a movie containing excerpts from previously unseen episodes of Life on Mars.

Participants from both groups will then be scanned after a delay of 4 weeks. On this occasion, they will view a new movie containing excerpts from previously unseen episodes of Life on Mars.

44
Q
  1. Are you using within or between subject?
A

It is a mixed design as between subject (original and scrambled) and within subject as both groups watching the movie immediately and after 4 week delay.

45
Q
  1. How are we defining regions of interest (ROIs) in the study? - (2)
A

For an MVPA approach, we are not defining regions of interest apriori as we are using search light approach with MVPA as looking at the whole brain to identify brain regions which correctly classify actor’s identity above chance level.

For DCM, focusing on direction of flow of information between core and extended system. Therefore, these regions needed to be defined. To do this, we can pick up coordinates that show in ISC and MVPA analysis. Picking up those areas showing above chance classification.

46
Q
  1. What is MVPA’s classifier? - (3)
A

A classifier is machine learning algorithm learns to associate patterns of brain activity with specific labels

Classifier is ‘trained’ on portion of dataset and told that certain brain activity correspond to different labels

The classifier is then tested on separate portion of dataset not used on training to classify in appropriate labels and its accuracy is observed

47
Q
  1. What is the difference between traditional univariate and MVPA? (4)
A

most of the fMRI studies for face recognition use univariate method of analysis in which each voxel is considered in isolation of others while its activation in response to task or stimulus is estimated.

It is, therefore, assumed that difference in response between the two stimuli, for example, familiar vs non-familiar faces can be observed at the singe voxel level.

The possibility that information could be encoded jointly by the voxels is ignored in the univariate method.

The multivariate pattern analysis (MVPA) (Haxby et al., 2001) overcomes this limitation by considering spatially distributed pattern of activity across voxels. The MVPA makes distinctions between the stimuli or tasks based on the pattern of activity

48
Q
  1. What are the 2 ways to do MVPA? - (2)
A

a. Region based = mark out brain regions like FFA ( used for specific hypothesis for region) and train classifier using all voxels of FFA and get y/n answer whether FFA classifier above chance or not.

b. Search light = do the whole base, don’t have specific hypothesis of brain, rather than marking brain regions, draw 6mm sphere and run classifier sphere within that sphere and run for whole brain by shifting sphere , contain 1 or more regions like contain FFA + OFFA , performance at whole brain which areas have above chance level

49
Q
  1. What is our aim with MVPA?
A

The first aim of the proposal is to use to use Multivariate Pattern Analysis (MVPA) (Haxby et al., 2001) to determine whether the neural representation of face identity is influenced by conceptual knowledge.

50
Q
  1. How are you using MVPA in your study? - (3)
A

Using MVPA, we will ask whether the pattern of response in different regions of the brain can predict the identity of a person.

To do this, we will compare the pattern of response when one identity is viewed in one part of the video with the pattern of response from a different part of the video.

The MVPA analysis will be performed using a searchlight approach on the whole brain to identify brain regions which correctly classify identity above chance level immediately after participants watch movie and after a delay.

51
Q
  1. What is your hypothesis of MVPA? - immediate - (2)
A

Since immediately after the movie, both groups of participants predominantly use perceptual information for recognition, the hypothesis is that brain areas of the core network will have above chance classification in both groups and that the performance between the two groups will not be significantly different.

In contrast, brain regions from the extended network will not show above chance classification in either group

52
Q
  1. What is your hypothesis of MVPA? - delay - (2)
A

Given that after a delay, there is a difference in the role of conceptual knowledge for recognition, the hypothesis is that brain areas of the extended network will have above chance classification in the Original group and that the performance will be significantly higher compared to the Scrambled group.

Since conceptual knowledge can also activate perceptual system, there will be above chance classification in the core network for Original group and this and this will not be so in the Scrambled group.

53
Q
  1. What is the aim of ISC in study?
A

The second aim of the proposal is to use Inter-subject correlation (ISC) to assess the role of conceptual information in face identification

54
Q
  1. How are you using ISC in your study?
A

To address this question, conssitency of neural responses to the movies shown without a delay and = delay will be compared in participants from the Original and Scrambled groups.

55
Q
  1. What is your hypothesis of ISC? - (4)
A

Since immediately after the movie, both groups of participants predominantly use perceptual information for recognition, the hypothesis is that brain areas of the core network will have high ISC in both groups and that the performance between the two groups will not be significantly different.

In contrast, brain regions from the extended network may not show high ISC in either group.

Given that after a delay, there is a difference in the role of conceptual knowledge for recognition, the hypothesis is that brain areas of the extended network will have higher ISC in the Original compared to the Scrambled group.

Since conceptual knowledge can also activate perceptual system, there may also be higher ISC in the core network for Original group.

56
Q
  1. What is our third aim with DCM?
A

The third aim is to understand causal interactions between the core and extended network using dynamic causal modelling (DCM) for fMRI

57
Q
  1. What is the hypothesis for DCM?
A

More specifically, the hypotheses to be tested are (i) the flow of information between core and extended network is influenced by conceptual knowledge and (ii) the flow of information has its directionality from extended to core network.

58
Q
  1. Why not use Granger causality instead of DCM? - (3)
A

Both are causal connectivity and give direction of flow of info (regression)

Granger is not based on neural activity and regression and can be applied to any sort of data

DCM tries to go at neural level as mathematical equation Friston that turns neural activity between regions to BOLD

59
Q
  1. What does functional connectivity not tell you?
A

functional connectivity, which does not tell the direction of flow of information,

60
Q
  1. What is forward, background and forward-background model in DCM? - (2)
A

For example, if there are two brain areas A and B and the objective is to understand which way the information flows between the two areas.

That is, whether A drives B (A -> B) or B drives A (A <- B).

61
Q
  1. In DCM for fMRI use different model it has (e.g., forward, backward, forward-backward) and… - (2)
A

compare them to find out which of the two has a better model fit based on the data.

The ‘best’ model will tell the structure of information flow.

62
Q
  1. How to identify causal flow of info in DCM in our study for core and extended? - (3)
A

To identify causal flow of information between the core and extended network for facial recognition, fMRI data and DCM will be used to estimate three types of models:

Forward model (core network drives the extended network), backward model (extended network drives the core network) and forward-backward model (both core and extended networks drives each other).

These models will be estimated and compared against each other, and the best model will be selected.

63
Q
  1. Hypothesis of DCM: - (2)
A

Since, conceptual knowledge can activate perceptual system, the hypothesis is that the backward model will be the best model in ‘Original’ group for the data acquired after the delay period when conceptual information is dominant for face recognition.

Since the backward flow of information in the Scrambled group would be absent, the best model for the Scrambled group would be the forward model.

64
Q
  1. DCM vs functional connectivity (correlational)?
A

Both DCM and functional connectivity give magnitude of strength of relationship of between different variables however what’s unique to DCM is that it gives the direction of flow of info whether its forward, backward or forward-backward