Agnostic Brain, Biased Mind - what does the FFA do?

Many neuroimaging studies have repeatedly found an area in the human brain that seems to be involved in processing visual faces. This area located in the fusiform gyri in humans, has been affectionately named the fusiform face area or FFA. The FFA is most active when we are looking at pictures of faces, and almost non-responsive to other types of visual items such as objects, houses, scenes, random textures, or a blank screen. Prosopagnosics, who are not able to recognize faces, but are still able to detect the presence of a face and also show no difficulty in processing other types of visual stimuli, have been shown to involve less FFA activity. Even more compelling, patients with lateral occipital lobes lesioned lose some form of object-processing, but show intact face processing. And yet other patients with lesions that have affected the FFA, have problems with face processing (acquired prosopagnosia) but intact processing for other stimuli. The evidence strongly suggests that there is something special about faces, and something about the FFA that deals with this specialization.

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.

Wicked Witch of the West steps on Scarecrow Brains with Magic Red Shoes

Charlene and I made this for Qinwei's birthday. We spent a whole week modifying things and planning what we could do to fit the Wizard of Oz theme. This is the result.

Ingredients

Green peppers

Red peppers

Bean sprouts

Rice

Can of corn

Carrots

Squash

Method

Cook the rice. Set it aside when done. First dice up the carrots and squash into small cubes. Make sure the corn is drained and dry. Pre-heat over to 350F. Start frying the carrots and squash in some oil. When they are almost done, add the corn and fry the mix for a few more minutes. Add the rice and mix the ingredients well under high heat. Add salt and pepper to taste. When done, cut the top off the green peppers, remove the seeds, and scoop the fried rice into the green peppers, making sure that they are compact. Coat the peppers with a little oil. Place the stuff green peppers into the oven, you can also bake the red pepper as well, it should take around 15-20 min. While the peppers are baking, stir fry the bean sprouts adding salt and pepper to taste. When the bean sprouts are done, lay them on the plate. Take the peppers out of the oven when done. Cut the red peppers into strips so that you can form little "shoes". Arrange them on the plate of bean sprouts, and place the whole green peppers on top of the red pepper shoes. Done! Wicked Witch of the West steps on Scarecrow Brains with her Magic Red Shoes.

3T Trio finds a new home in Beckman Institute

The Siemens 3T Trio is a full body MRI scanner. The Beckman Institute just recently acquired it. Today, the machine was brought to the basement of the Beckman building and we were fortunate enough to have some free time to glimpsed part of the process.

The scanner was brought in through a hole they have in the back of the building. It had rained the night before, so the ground around the hole was a little soggy. More importantly, they had to move fast because more rain was coming. The movers had to remove the heavy covers on the hole, lift the magnet bore and lower it into the basement, where there is a trolley for them to push the magnet into its final place. The movers took a break halfway because the rain did come anyway, before they could finish, but they continued later. As far as I know, the scanner is in the basement now, just waiting to be tested and used!

This is a full-body scanner, compared to the head-only scanner 3T Allegra. It should provide more uniform signal, although the 3T Allegra is sometimes better for certain sequences, or so I hear. So we'll see which one shines. They will move the 3T Allegra, head-only scanner, which is right now at the BIC down south, up into the Beckman basement as well, once this Trio is fully functional. There will still be about a month or so of testing and installation before we can begin to use it.

If you are my Facebook friend, you can check out other photos I have of this there [Facebook photo link].