Cognitive Labs

Using advanced brain imaging techniques, researchers at Georgetown University Medical Center have watched how humans use both lower and higher brain processes to learn novel tasks, an advance they say may help speed up the teaching of new skills as well as offer strategies to retrain people with perceptual deficits due to autism.

In the March 15 issue of Neuron, the research team provides the first human evidence for a two-stage model of how a person learns to place objects into categories discerning, for example, that a green apple, and not a green tennis ball, belongs to "food." They describe it as a complex interplay between neurons that process stimulus shape ("bottom-up") and more sophisticated brain areas that discriminate between these shapes to categorize and "label" that information ("top-down").

A human can't function without the ability to sort between objects and organize them in fluid ways, said the study's lead author, Maximilian Riesenhuber, Ph.D., the principal investigator for the Laboratory for Computational Cognitive Neuroscience. "We make sense of the world by learning to recognize objects as members of categories such as 'food,' 'friend,' or 'foe,' but it has not been clear how the human brain does this," he said.

The researchers theorized that a very simple yet efficient way of doing this kind of learning would be for the brain to first learn how objects vary in shape, and then, in a second stage, to learn which shapes go with which labels, allowing the brain to sort an object into different labeled "bins" when necessary. For example, a green apple and a green tennis ball are both green and round, but only an apple can be eaten and only a green tennis ball belongs to a sport.

In this study, the research team asked human volunteers to undertake a series of tasks presented to them on a computer screen. All of them involved cars that were generated with a computer graphics morphing system, allowing the researchers to generate thousands of cars with subtle shape differences. "In the beginning, all the cars looked very similar to the participants because they did not have any experience with them," said Riesenhuber. "It's like if a person had never seen faces before, they would all look similar at first."

In the first experiment, the participants looked at series of cars presented at different parts of the screen and performed simple position judgments on the images, while their brain activity was being measured using an advanced functional Magnetic Resonance Imaging (fMRI) technique that made it possible to more directly probe neuronal tuning than in previous studies. Investigators found that cars activated a particular region in participants' brains, the lateral occipital cortex, which had also been found by other studies to be important for object recognition.

Then the volunteers were given several hours of training using images of the cars. In these sessions, participants had to learn how to group the cars into two distinct categories. This was easy at first, Riesenhuber said, because the cars were obviously not alike, but then the researchers began to "tighten the screws" by making the two categories increasingly more similar.

"Over the course of the training, the participants got better at finer and finer category discriminations," Riesenhuber said. "This represents a crucial step in category learning where small differences in shape can have a big impact on category labels -- as in the tennis ball and apple example -- and where big differences in shape -- such as between an apple and a banana -- can have no impact on the label, such as when categorizing both as 'fruit'."

Now that the volunteers had learned how to categorize small shape changes, they were shown the cars from the first experiment while again being scanned, allowing the researchers to compare how training had enhanced the brain's ability to process car shapes. They found again that cars selectively activated an area in lateral occipital cortex, but that now neurons in that area appeared to be finely tuned to small car shape differences.

In a third scan, the investigators finally asked subjects to categorize the same car images shown in the other scans. This time, two areas of the brain, the now familiar area in lateral occipital cortex as well as an area in lateral prefrontal cortex, were found to be active when processing the images. "The lateral prefrontal cortex is known to be the center of cognitive control," Riesenhuber said. "That is where the brain connects physical input to an action or response, deciding what task to do and how to respond to a stimulus."

In essence, fMRI was showing that both the higher and lower brain regions had worked together to learn a task, he said.

These findings might be helpful in understanding disorders that involve differences in the interaction of bottom-up and top-down information in the brain, such as autism or schizophrenia, Riesenhuber said. It also suggests how the learning of visual skills can be enhanced by directly monitoring neuronal activity. "This could be useful, for instance, to speed up learning to detect targets in unfamiliar imaging modalities, such as baggage X rays or radar images," he said.

The study was funded by grants from the National Institutes of Health and a National Science Foundation CAREER award to Riesenhuber. Co-authors include, from Georgetown University, first author Xiong Jiang, Ph.D., Evan Bradley, B.S., Regina Rini, B.A., and John VanMeter, Ph.D.; and Thomas Zeffiro, M.D., Ph.D., from Massachusetts General Hospital.

Labels: learning

Exercising your mind does pay off - for the first time, scientists have shown that learning slows the build-up in the brain of protein plaques and tangles that are the signature of Alzheimer's disease.

Although the study was conducted in mice, it does reinforce the idea that, in humans, maintaining an active mind may help delay or even prevent Alzheimer's disease.

"This has shown for the first time that using your brain can protect you physically," said Kim Green, co-lead author of the study and a postdoctoral researcher at the University of California, Irvine. "We show that when you do this, it causes changes in the brain, and these changes are protective."

"It's an interesting study, and part of what it does is advance the notion that mental exercise has a protective effect against Alzheimer's," said Dr. Gary Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York City.

According to the Alzheimer's Association, about 4.5 million Americans have the brain-robbing disorder, a number that has more than doubled since 1980. Many more suffer from cognitive impairment, which could be a harbinger of Alzheimer's.

Many experts believe that Alzheimer's is caused by a steady accumulation of amyloid plaque proteins in the brain.

Previous studies had shown that "mental exercise" could delay the onset of the disease, but the proof came only in the form of memory and other cognitive testing measures.

The study involved hundreds of "transgenic" mice -- mice that had been genetically altered to develop human Alzheimer's disease.

Mice in a "learning" group were allowed to swim in a tank of water until they discovered a submerged platform on which to stand. This training took place four times a day for one week at two, six, nine, 12, 15 and 18 months of age. The other group of mice swam in the tank just once before their learning and memory skills were tested and their brains examined.


Mice up to 1 year old in the learning group developed 60 percent less of the proteins that form plaques and tangles compared to mice in the non-learning group, the researchers found.

"The sort of learning we gave the animals was fairly mild, yet it still had a big effect," Green said.

However, by 15 months of age, the learning mice had declined and were now physically and cognitively identical to the non-learning mice.
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Can these findings be extrapolated to humans?

"We do find a lot of similarities, but clinical data also backs up what we've shown in this study," Green said.

"I think it's reasonable to extrapolate," Kennedy added. "The recommendation certainly is to keep your mind active."

"Think of the brain as a computer," Kennedy continued. "Alzheimer's degrades the hardware, and education enhances the software. The brain is also a muscle, and conditioning may protect it."

Green and his colleagues hope to use the information to one day develop a drug for the disease.

"We want to identify exactly how learning influences pathology and identify a novel drug target," he said.


The study is appearing in the Jan. 24 issue of the Journal of Neuroscience.

Labels: alzheimers, brain, learning, neuroscience, uc-irvine

With the Coming of the New Year, you'll now be able to test and train your brain a little bit, or a lot.

There are several completely new exercises and, in addition, on every test there is an intensity adjuster. Start low, at 5 or 10 repetitions - and increase to 30 or 40 repetitions as you get more proficient.

This might remind you of a routine at the gym.

As you increase your ability to concentrate and focus, you'll begin to change your brain for the better. As the experts have said, regular workouts for an extended period of time are the key. But even if you can only spend a few minutes a day, with the lower rep settings you can exercise your brain in just a few minutes - with a variety of exercises that focus on different memory and attention capacities - a much more concentrated form of exercise than suggestions to "read" or do "crossworld puzzles," and 2X to 3X more effective, in less time according to a recent JAMA article, with benefits measureable many years into the future.

While they may be fun, crosswords don't have a time element. Time-definite exercise trains your brain to be quicker through enhancement of "neural conduction velocity" which is the scientific term used for "brain speed."

These changes can make your brain act younger by stimulating neural connections and if you are young, increase the potential to learn, store, and recall information. The variety and depth insures that you get a balanced exercise.

Labels: alzheimers, brain, brainage, brainspeed, learning, neural, nintendo, velocity, youth