Showing posts with label Comment. Show all posts
Showing posts with label Comment. Show all posts
Monday, March 12, 2012
Depth and Breadth for an Efficient Brain: No Short Cuts
A recent development in our understanding of neural structure might be mapped onto this set of physical properties. Based on graph theory, we now know that the way in which the human brain is wired resembles a small-world network. That is, neurons are connected to each other in the brain such that there is an optimal balance between short-distance, local, connections with close neighboring neurons, as well as long-distance connections via hub neurons. This balance of having both types of connections results in the most efficient structure with which information can be transmitted from one neuron to another, on average. Too many local connections, and information must shuttle through an adverse number of short-range synapses before reaching a distant neuron, increasing time of transfer. Too many long-distance connections, and also information must ridiculously pass through distant neurons before arriving at the neuron which is just beside. Other properties emerge that also are used to characterize the degree to which a network is a small-world network - level of clustering and randomness of connections. Using such indices, we now know that the evident connectivity of the brain seems to represent a high-level of efficiency with regards to the processing of information pertaining to stimuli, memory, thought, and action. Because of such neural organization, we are able to read or hear, comprehend, remember, reason, and respond, all literally within the blink of an eye.
With this background, we come back to the opening questions. If our brains are generally already efficient, how does this efficiency change with age, and if it goes down (as we are apt to assume), how do we keep it at optimum efficiency for as long as possible apart from the use of chemical and physical interventions? How do we optimize our small-world networks via mental interventions?
Friday, March 05, 2010
Reduced Neural Selectivity Increases fMRI Adaptation with Age during Face Discrimination
Key project finally published! This took quite a while, but it was worth it.
[Link to article if you have journal access]
[Link to Pubmed abstract access]
By Joshua O., Goh , Atsunobu, Suzuki , Denise C., Park
Beckman Institute, University of Illinois, Urbana-Champaign, IL, USA; Center for Vital Longevity, University of Texas, Dallas, TX, USA.
Ventral-visual activity in older adults has been characterized by dedifferentiation, or reduced distinctiveness, of responses to different categories of visual stimuli such as faces and houses, that typically elicit highly specialized responses in the fusiform and parahippocampal brain regions respectively in young adults (Park et al., 2004). In the present study, we demonstrate that age-related neural dedifferentiation applies to within-category stimuli (different types of faces) as well, such that older adults process less distinctive representations for individual faces than young adults. We performed a functional magnetic resonance imaging adaptation experiment while young and older participants made same-different judgments to serially presented face-pairs that were Identical, Moderate in similarity through morphing, or Different. As expected, older adults showed adaptation in the fusiform face area (FFA), during the Identical as well as the Moderate conditions relative to the Different condition. Young adults showed adaptation during the Identical condition, but minimal adaptation to the Moderate condition. These results indicate that older adults' FFA treated the morphed faces as Identical faces, reflecting decreased fidelity of neural representation of faces with age.
NeuroImage, In Press, Accepted Manuscript, Available online 6 February 2010
[Link to article if you have journal access]
[Link to Pubmed abstract access]
By Joshua O., Goh , Atsunobu, Suzuki , Denise C., Park
Beckman Institute, University of Illinois, Urbana-Champaign, IL, USA; Center for Vital Longevity, University of Texas, Dallas, TX, USA.
Ventral-visual activity in older adults has been characterized by dedifferentiation, or reduced distinctiveness, of responses to different categories of visual stimuli such as faces and houses, that typically elicit highly specialized responses in the fusiform and parahippocampal brain regions respectively in young adults (Park et al., 2004). In the present study, we demonstrate that age-related neural dedifferentiation applies to within-category stimuli (different types of faces) as well, such that older adults process less distinctive representations for individual faces than young adults. We performed a functional magnetic resonance imaging adaptation experiment while young and older participants made same-different judgments to serially presented face-pairs that were Identical, Moderate in similarity through morphing, or Different. As expected, older adults showed adaptation in the fusiform face area (FFA), during the Identical as well as the Moderate conditions relative to the Different condition. Young adults showed adaptation during the Identical condition, but minimal adaptation to the Moderate condition. These results indicate that older adults' FFA treated the morphed faces as Identical faces, reflecting decreased fidelity of neural representation of faces with age.
NeuroImage, In Press, Accepted Manuscript, Available online 6 February 2010
Sunday, February 28, 2010
Origami and the Brain
For example, some rules may be related to the fact that our neurons have many short range local connections with neighboring neurons, as well as, some long range connections to more distant groups of neurons. Establishing and pruning these connections is dependent on time and stimulation from external as well as internal events. These events can be cognitive or biological or physical (e.g. the intention to retrieve a memory, or some neurotransmitter regulation, or some visual energy input, respectively). Within this system, our brains try to represent external information, and to generate certain actions or responses.
In a similar manner, in origami, each fold is like an imprint of an event that happens. The effect of folding, however, is limited by the thickness, elasticity, and size of the paper, as well as the force of the folding. Folding could be a sharp strong crease, a light depression, or a curve. Folding also occurs along specific lines or regions on the paper at a time. Finally, folding has temporal order. Through a combination of these factors, the paper encodes what forces have been exerted on it, and represents all of that in a particular physical form. The end state.
The end state maybe be a meaningful shape, or it may have a meaningful function. We can transform a simple piece of paper into a form of a crane, or a box, or a really complex shape (origami experts have been able to do wonders!). We can even use the tension inherent in the folded paper as a spring with tremendous kinetic energy when released. We can also use folding to allow a large piece of material that ordinarily would not fit in specific area to conform to the shape and therefore fit in the area.
Likewise, the brain performs an interesting function in incorporating sensory information from the physical world and representing all the rich material within a single piece of organic tissue. This "folding" of information from one state to another may be a framework to understand neural function.
Consider that we can quantify the physical forces and characteristics of a piece of paper and its folds. Based on low level parameters, we can then determine what the origami will look like, what it can do, what properties its resulting form maintains. Applying a similar method to parameterize neural function may allow us to better describe how the properties of the brain relate to cognition and behavior. For example, the ease with which a paper folds may be dependent on the thickness of the paper (for a given material elasticity/rigidity/brittleness). This will in turn determine how much force must be applied to the paper to achieve a fold of a certain angle. In the same way, one property of the brain may be how strong the connections in a certain neuronal region may be. The stronger the connections, the easier it may be for a signal in one region to affect the activity in another. Another case in point, the brain maintains a certain level to generate new neurons in key parts of the cortex. Neurogenesis is known to occur even in late adulthood in the hippocampus and the peri-ventricular walls. Importantly, recent studies have shown that neurogenesis may be helpful in overcoming drug addiction. A possible mechanism might be that the new neurons enable the brain to represent existing addiction behaviors (information "folding"), in a new way that discourages addiction [link to relevant post]. Moreover, it is possible that different individuals have different rates, or ability, of neurogenesis, and external events or neurochemical interventions may also encourage neurogenesis. It is this rate of neurogenesis that might be a candidate parameter that determines how much a particular brain can fold.
Of course, this is all analogical. There is no necessary association between paper and brain. But, this presents an interesting way to approach the problem of quantifying brain function. Paper folding has been applied to several interesting real life problems. For example, the folding of solar-energy panels into a satellite so that large plates fit into a small structure for launching, and unfold in space to achieve maximum surface area for efficient energy collection. In addition, protein folding occurs according to the electro-chemical forces at the molecular level. Paper folding has been applied to understanding and even manipulating these forces to make protein molecules that achieve specific helpful biomolecular functions. Here's an example of applying origami to practical problem from an MIT group [link].
After all, the reason why origami is meaningful, is because we perceive cranes in a few simple folds.
Saturday, February 27, 2010
The Automation of Science
Article from Science:
[REPORTS] The Automation of Science
"A robot scientist discovers orphan enzymes that take part in yeast metabolism."
This was published a while ago. But it may be worth mentioning because it could be the pivotal moment in AI.
[REPORTS] The Automation of Science
"A robot scientist discovers orphan enzymes that take part in yeast metabolism."
This was published a while ago. But it may be worth mentioning because it could be the pivotal moment in AI.
Increasing neurogenesis might prevent drug addiction and relapse
Article from ScienceDaily:
Increasing neurogenesis might prevent drug addiction and relapse
"Researchers hope they have begun paving a new pathway in the fight against drug dependence.
"
This makes computational sense. Adding new neurons creates the possibility of forming new inhibitory connections, as well as de-potentiating the strength, or contribution, of existing ones. Such predifferentiated neurons serve as fresh unwritten computational space for which new behaviors and cognitions can be learned. In addition, old pathways which have been entrained and which are hard to change (because of prolonged experience or intensity) can have their effects counterbalanced.
Increasing neurogenesis might prevent drug addiction and relapse
"Researchers hope they have begun paving a new pathway in the fight against drug dependence.
This makes computational sense. Adding new neurons creates the possibility of forming new inhibitory connections, as well as de-potentiating the strength, or contribution, of existing ones. Such predifferentiated neurons serve as fresh unwritten computational space for which new behaviors and cognitions can be learned. In addition, old pathways which have been entrained and which are hard to change (because of prolonged experience or intensity) can have their effects counterbalanced.
Friday, January 01, 2010
New Year Thoughts
"Beloved, let us love one another, for love is of God; and everyone who loves is born of God and knows God. He who does not love does not know God, for God is love. In this the love of God was manifested toward us, that God has sent His only begotten Son into the world, that we might live through Him. In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. Beloved, if God so loved us, we also ought to love one another.
"No one has seen God at any time. If we love one another, God abides in us, and His love has been perfected in us. By this we know that we abide in Him, and He in us, because He has given us of His Spirit. And we have seen and testify that the Father has sent the Son as Savior of the world. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. And we have known and believed the love that God has for us. God is love, and he who abides in love abides in God, and God in him.
"Love has been perfected among us in this: that we may have boldness in the day of judgment; because as He is, so are we in this world. There is no fear in love; but perfect love casts out fear, because fear involves torment. But he who fears has not been made perfect in love. We love Him because He first loved us.
"If someone says, "I love God," and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen? And this commandment we have from Him: that he who loves God must love his brother also."
1 John 4:7-21
How difficult it is to love! How easy it is to know we have to do it, to say it. But it is next to impossible to do it. John gives a good reminder that inspires and defines for us what life we should be living. If we chase after anything, it should be love. For God is love. This is the contemplation on the eve of 2009.
Merry Christmas and a Happy New Year.
"No one has seen God at any time. If we love one another, God abides in us, and His love has been perfected in us. By this we know that we abide in Him, and He in us, because He has given us of His Spirit. And we have seen and testify that the Father has sent the Son as Savior of the world. Whoever confesses that Jesus is the Son of God, God abides in him, and he in God. And we have known and believed the love that God has for us. God is love, and he who abides in love abides in God, and God in him.
"Love has been perfected among us in this: that we may have boldness in the day of judgment; because as He is, so are we in this world. There is no fear in love; but perfect love casts out fear, because fear involves torment. But he who fears has not been made perfect in love. We love Him because He first loved us.
"If someone says, "I love God," and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen? And this commandment we have from Him: that he who loves God must love his brother also."
1 John 4:7-21
How difficult it is to love! How easy it is to know we have to do it, to say it. But it is next to impossible to do it. John gives a good reminder that inspires and defines for us what life we should be living. If we chase after anything, it should be love. For God is love. This is the contemplation on the eve of 2009.
Merry Christmas and a Happy New Year.
Monday, December 07, 2009
Separation vs. Association
A key function of the brain is to first, process the fact that we are encountering different types of stimuli at every moment, and second, process the simultaneous fact that while there are these different types of stimuli, there are also many consistencies that reflect modifications of the same stimulus at a higher level of abstraction.
One way to evaluate what a cortical region may be doing with respect to this separation/association dichotomy may be to determine the number of neurons at the first level relative to the second level.
If the ratio of neurons at the first relative to second level is large, then the function of the second level is probably to associate. This is a many-to-few limitation. So various permutations and combinations at the first level are funneled into the reduced dimensionality of the second level. Therefore, some combinations are subsumed.
If the ratio of neurons from first to second levels is small, then there is the potential for expansion. The problem becomes a few-to-many scenario. The same combination at the first level may elicit several possible outcomes at the second level. There is information expansion.
...
One way to evaluate what a cortical region may be doing with respect to this separation/association dichotomy may be to determine the number of neurons at the first level relative to the second level.
If the ratio of neurons at the first relative to second level is large, then the function of the second level is probably to associate. This is a many-to-few limitation. So various permutations and combinations at the first level are funneled into the reduced dimensionality of the second level. Therefore, some combinations are subsumed.
If the ratio of neurons from first to second levels is small, then there is the potential for expansion. The problem becomes a few-to-many scenario. The same combination at the first level may elicit several possible outcomes at the second level. There is information expansion.
...
Saturday, December 05, 2009
Slicing up HM's brain
Watch HM's brain being documented, slice by slice.
Click here for live link. At the time of this posting, they are already at the occipital structures. So they may finish soon. Not sure what will happen to the link or the video once this entire process is done.
HM was a famous epileptic patient who had much of his medial temporal structures removed as a treatment for the epilepsy. The result of this operation rendered HM unable to form new long-term memories. This finding was instrumental in the notion that the medial temporal structures, such as the hippocampus, is important for memory. Since his operation, HM has been heavily studied. HM passed away on the 8 Dec 2008 due to respiratory failure. [More about HM]
Click here for live link. At the time of this posting, they are already at the occipital structures. So they may finish soon. Not sure what will happen to the link or the video once this entire process is done.
HM was a famous epileptic patient who had much of his medial temporal structures removed as a treatment for the epilepsy. The result of this operation rendered HM unable to form new long-term memories. This finding was instrumental in the notion that the medial temporal structures, such as the hippocampus, is important for memory. Since his operation, HM has been heavily studied. HM passed away on the 8 Dec 2008 due to respiratory failure. [More about HM]
Friday, October 09, 2009
Developments after...
This has got to be the wettest year ever. The rains got so bad this year that snow aphids snowed down on our small little town of Champaign. Winter rears its cold face around the corner now.
The reason why I am posting this now, is because I have just returned from a series of inspirational events. Traveling north and south between Champaign and Dallas takes its toll at times. You get up early at 6am, clean up, and get on the 7.30am flight (2 hrs). Reach DFW. Get onto the shuttle for the rental car mall of the airport (takes 15min). Get the car, drive to the Dallas lab (20min). Work. Check-in to Embassy Suites (which is an awesome hotel!). And on trips back, leave the lab by 4pm. Return the rental car, take the shuttle to terminal B of DFW. Pass security. Have a beer and a burger at TGIF in the airport before getting on the 6.50pm flight back to Champaign, and be picked up by a familiar face.
Do this 20 times.
Recently though, work has been progressing. Papers are being submitted. Finally. And hopefully accepted! But I think the most inspiring event happened yesterday. Instead of going south, I headed north and gave talks at Northwestern. The data seems well received and everyone seems so interested and in agreement. I felt glad. It was worthwhile to drive up 3hrs and back 3hrs for that one day of wonderful meetings and interactions.
Now, the main concern are next steps. Where to go after this one year of post-doctoral research? Another post-doctoral position? Faculty? Tough decisions with too many factors that plague my mind, that give no clear direction. No amount of grad school prepares you for this! For life!
One can only dive in.
The reason why I am posting this now, is because I have just returned from a series of inspirational events. Traveling north and south between Champaign and Dallas takes its toll at times. You get up early at 6am, clean up, and get on the 7.30am flight (2 hrs). Reach DFW. Get onto the shuttle for the rental car mall of the airport (takes 15min). Get the car, drive to the Dallas lab (20min). Work. Check-in to Embassy Suites (which is an awesome hotel!). And on trips back, leave the lab by 4pm. Return the rental car, take the shuttle to terminal B of DFW. Pass security. Have a beer and a burger at TGIF in the airport before getting on the 6.50pm flight back to Champaign, and be picked up by a familiar face.
Do this 20 times.
Recently though, work has been progressing. Papers are being submitted. Finally. And hopefully accepted! But I think the most inspiring event happened yesterday. Instead of going south, I headed north and gave talks at Northwestern. The data seems well received and everyone seems so interested and in agreement. I felt glad. It was worthwhile to drive up 3hrs and back 3hrs for that one day of wonderful meetings and interactions.
Now, the main concern are next steps. Where to go after this one year of post-doctoral research? Another post-doctoral position? Faculty? Tough decisions with too many factors that plague my mind, that give no clear direction. No amount of grad school prepares you for this! For life!
One can only dive in.
Saturday, August 29, 2009
PhD
Well, it is the start of the first weekend after defending. How was the defense? It was utterly fun. How often can you squash 5 brilliant minds in one room and have them talk about your work? How often can you debate with them and have them listen to your thoughts on things? How often can you hear them agree or even disagree with you in the most honest sense of it all? I would wish this on anybody who dares to try.
No one knows it all. But the defense is about stating what you know, and what you know you don't know. It is about being honest, and seeking truth. If what you find is real, it will bear itself. If what you think is true, you will find it. Sound familiar?
After the defense, we all went to Jim Gould's to have dinner. And it was, how shall I put it, fun! I think I felt it, that warmth of accomplishment. So that food tastes better. Sweetness has a fragrance, salt floods with depth, sour comes with juiciness, and bitter? There is no bitter.
Soon after, we watched an amazing movie - Inglorious Basterds! What a choice right? Brad Pitt was brilliant. Incidentally, Brangelina was in my defense.
The next day, I cleaned up the mess that was my apartment. It felt good to exert mindless sweat. The day after, we watched Mamma Mia. Tomorrow, BBQ!
That's what PhD is about, what happens before and after.
No one knows it all. But the defense is about stating what you know, and what you know you don't know. It is about being honest, and seeking truth. If what you find is real, it will bear itself. If what you think is true, you will find it. Sound familiar?
After the defense, we all went to Jim Gould's to have dinner. And it was, how shall I put it, fun! I think I felt it, that warmth of accomplishment. So that food tastes better. Sweetness has a fragrance, salt floods with depth, sour comes with juiciness, and bitter? There is no bitter.
Soon after, we watched an amazing movie - Inglorious Basterds! What a choice right? Brad Pitt was brilliant. Incidentally, Brangelina was in my defense.
The next day, I cleaned up the mess that was my apartment. It felt good to exert mindless sweat. The day after, we watched Mamma Mia. Tomorrow, BBQ!
That's what PhD is about, what happens before and after.
Tuesday, August 18, 2009
On the road to Permanent Head Damage
It is just one more week to the final defense. The big D day literally. I have submitted my dissertation draft, after reading it for the hundredth time, re-crunching the numbers for the thousandth, and clicked the save button on Word for the millionth time. After sending the document off, and the first thought that came to mind was how stupid I was. Really. After devoting a whole month of intense thought on the data, I realize that that's all I really knew. And the other things around me took on their own life, grew up, and now, I don't recognitize them. So its going to take a while to reintegrate back into reality.
Now, its just one more powerpoint to go, and then...the same-o same-o. I sure hope all this is worth it! So far, it seems to be. If not for anything then just because life becomes a little clearer as we find out a little more, each step.
I like Douglas Adam's thought: Someone somewhere theorized that the minute a human being sits down and figures out how the universe works, it would immediately be replaced by another more complex universe...some say that this has already happened. Really, what I think about all this is that everything is like a donut. Nuff said.
Now, its just one more powerpoint to go, and then...the same-o same-o. I sure hope all this is worth it! So far, it seems to be. If not for anything then just because life becomes a little clearer as we find out a little more, each step.
I like Douglas Adam's thought: Someone somewhere theorized that the minute a human being sits down and figures out how the universe works, it would immediately be replaced by another more complex universe...some say that this has already happened. Really, what I think about all this is that everything is like a donut. Nuff said.
Thursday, July 16, 2009
Agnostic Brain, Biased Mind - what does the FFA do?

The debate regarding the FFA pertain to whether it is the only region or even a critical region that does face processing. Some labs have shown that face processing information can be found in other regions of the brain that are not the FFA. Yet some labs have shown that the FFA is recruited to process fine levels of category distinctions. For example, bird and car experts have been shown to engage some level of FFA activity when processing these stimuli compared to novices. These findings suggest that the FFA is not processing faces per se, but visual representations that have come to require high-levels of fine discrimination through experience, of which faces are the best example of this currently.
I suggest that a more flexible definition is called for when thinking about the FFA and its role in processing visual information. Certainly, it does seem that faces occupy a special place in human experiences. On the other hand, it is difficult to explain why there would be a brain region that codes for faces and faces along based simply based on genetic or biologically determined causes.
In terms of a neural network, if indeed the brain consists of many different sub-types of neural networks that conglomerate to form one large complex network, the FFA is a sub-network specialized to perform a specific operation that is maximized and specialized (trained) for a specific information domain - faces. This or these specific operation(s) could involve identification, discrimination, recognition, or all of these, or even a yet unknown operation. Certainly neural network non-linearities can surprise us! Moreover, these operations have been tuned for a specialized class of stimuli that consists of eyes, nose, mouths, and other visual characteristics of faces when occurring together as a whole (whether from external input, or through internal imagination or retrieval).
What this means is that if you were able to "remove" the FFA, and plug it into a computer so that you can feed this FFA network with inputs and measure its outputs, you could theoretically feed it anything, but the information would be most meaningful or organized when the inputs correspond to information about a face. Of course, this would require us to know what is the language of the input to perform such an experiment.
Other types of inputs may elicit some level of meaningful output of the FFA. Neural network do that. Yet other types may elicit nothing at all. This does not necessarily mean that the FFA outputs from such inputs is useless, nor does necessarily mean that it is used! It is just output. What higher-level brain mechanisms do with the output depends on the task, and how the brain is wired to treat outputs from its sub-networks. It may be ignored, or it may actually incorporate relevant information. That is, the FFA is agnostic to the incoming information. It does not care. It will process it anyway. But other regions decide whether what is it saying needs to be incorporated or not, or if it should be further modified even.
Such a view would reconcile why the FFA is special for faces, yet seems to be carrying some information about other stimuli. It would also be consistent with the idea that information about faces is certainly also available to a certain extent in non-FFA regions, the same principles being applied to these other sub-networks. It would also be consistent with how self-organizing behavior in neural network (see von der Malsburg article [link]) can lead to a consistent topology across every person that processes a particular stimulus in a particular way in a particular spatial location.
This is probably not a new idea, but needs to be clarified in the literature I think.
Friday, May 15, 2009
Cognitive abilities in kindergartners and first graders: A comparison, evaluation, and extension of models using data from Robinson et al. (1996)
Paper submitted for final in structural equation modeling class, Spring 2009, UIUC Psychology. This paper is a critique of Robinson et al.'s (1996) paper on "The structure of abilities in math-precocious young children: Gender similarities and differences", published in the Journal of Educational Psychology (Vol. 88, Iss. 2, p341-352). This current paper, though, focuses on the age differences in abilities of kindergartners and first graders.
It is known that very young children show less differentiated cognitive abilities. Children who perform well in tests such as those involving math, tend to have correlated performance in other tests such as in verbal tests. As children age and progress towards adolescence, however, their cognitive abilities becomes differentiated so that abilities such as math and verbal abilities are not necessarily equally developed in the child.
Presumably, this occurs because when children are very young, they are untrained and unaffected by external factors such as education and related experiences (e.g. streaming into majors). Thus, the best predictor of the child's performance is the individual difference or a general factor. With age, the child undergoes specialization where children start to develop more specific knowledge in selective domains. Some children become more trained at math, while others at language. Importantly, these abilities aren't always equally developed. This may be the underlying reason for differentiated abilities in older children.
This current paper is a methodological exploration of the data in Robinson et al. (1996) using various modifications of the basic structural equation model. The main results are consistent with differentiated abilities in first graders relative to kindergartners. Some discrepancies in Robinson et al.'s (1996) paper are noted as well.
[Download pdf of paper]
It is known that very young children show less differentiated cognitive abilities. Children who perform well in tests such as those involving math, tend to have correlated performance in other tests such as in verbal tests. As children age and progress towards adolescence, however, their cognitive abilities becomes differentiated so that abilities such as math and verbal abilities are not necessarily equally developed in the child.
Presumably, this occurs because when children are very young, they are untrained and unaffected by external factors such as education and related experiences (e.g. streaming into majors). Thus, the best predictor of the child's performance is the individual difference or a general factor. With age, the child undergoes specialization where children start to develop more specific knowledge in selective domains. Some children become more trained at math, while others at language. Importantly, these abilities aren't always equally developed. This may be the underlying reason for differentiated abilities in older children.
This current paper is a methodological exploration of the data in Robinson et al. (1996) using various modifications of the basic structural equation model. The main results are consistent with differentiated abilities in first graders relative to kindergartners. Some discrepancies in Robinson et al.'s (1996) paper are noted as well.
[Download pdf of paper]
Tuesday, May 12, 2009
VSS Conference Day 4: My Poster

In this study, however, I postulated that under certain circumstances, the brain requires more neuronal recruitment in order to effectively process information for task demands. That is, repetition suppression becomes inefficient because it reduces the degrees of freedom that the brain can use to manipulate existing representations.
The study evaluated brain response in the fusiform region to face-pairs morphed at different levels of similarity. The idea is that the more similar face-pairs are, the more repetition suppression should be observed in the fusiform face area. Participants viewed the face-pairs under two different task instructions. The first task made face-pair similarity irrelevant. In this task, repetition suppression was observed to repeated faces. In the second task, face-pairs were made critical as participants had to make same-different judgments about the pairs. In this task, repetition suppression was eliminated.
The idea here is that in the same-different judgment task, the brain has to represent faces as distinctinctively as possible so that subtle morph differences can be detected. Thus, repetition suppression is prevented, possibly from executive function areas that process task instruction and exert a top-down modulatory control in the fusiform area.
The study also shows that there are individual differences in participants ability to exert this top-down modulation to regulate repetition suppression in the fusiform regions. This study was also performed in older adults, which will be reported in a subsequent research article. Briefly though, it is thought that older adults show declines in behavioral performance because of less distinctiveness in cognitive representations. This design is thus useful as a means to measure and related distinctinveness of representations in the brain and how that affects behavior.
Monday, May 11, 2009
Sunday, May 10, 2009
Wednesday, May 06, 2009
A structural model of aging, brain and behavior

Thursday, April 16, 2009
My View on the Singapore River...Apparently!

Ha ha, forgot that I did this for Elaine long long time ago. Wow! Check out my interview.
Monday, December 15, 2008
A Good Wine
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