Archive for the ‘perception’ Category

New research on the neural system of language

December 7, 2011

Neuroscientists have long known that particular areas of the brain are responsible for the comprehension and production of language. But new research points to the criticality of pathways between these areas for various components of language.

From a Science Daily article summarizing the research:

Two brain areas called Broca’s region and Wernicke’s region serve as the main computing hubs underlying language processing, with dense bundles of nerve fibers linking the two, much like fiber optic cables connecting computer servers. But while it was known that Broca’s and Wernicke’s region are connected by upper and a lower white matter pathways, most research had focused on the nerve cells clustered inside the two language-processing regions themselves.

MRI image shows Brocca's (yellow) and Wernicke's (purple) regions, connected by critical neural pathways. (Image credit: Stephen Wilson, Science Daily)

University of Arizona Professor of Speech and Hearing Stephen Wilson was one of the lead researchers:

If you have damage to the lower pathway, you have damage to the lexicon and semantics. You forget the name of things, you forget the meaning of words. But surprisingly, you’re extremely good at constructing sentences.

With damage to the upper pathway, the opposite is true; patients name things quite well, they know the words, they can understand them, they can remember them, but when it comes to figuring out the meaning of a complex sentence, they are going to fail.

Professor Wilson collaborated on the research with colleagues from the University of California at San Francisco and the Scientific Institute and University Hospital San Raffaele in Milan, Italy. The research was published in the journal Neuron.

Ruminations of a brain scientist who also likes to party

November 2, 2011

Tuesday’s NY Times has a fascinating profile of Dr. Michael Gazzaniga, a professor of psychology at the University of California, Santa Barbara, who led pioneering research into the interaction of the various systems of the brain. Dr. Gazzaniga’s research focused on patients who had surgery to separate the hemispheres of the brain (used as a treatment for severe epilepsy). The research uncovered the presence of a left-brain-centered brain narrating system that creates a coherent voice from the inputs of many brain systems.

The Times article summarizes Dr. Gazzaniga’s research, but also provides some insight into the man who, among other things, was a member of the fraternity at Dartmouth that inspired the movie “Animal House”, and who says of his fellow researchers at Cal Tech “we weren’t intellectuals, in the sense that we were going out to see people lecturing or cultural events in the evening. That was martini time.” The profile of Dr. Gazzaniga by the Times is part of its series about leaders in science, and includes a video interview.

Dr. Gazzaniga’s new book, which examines the implications of the brain’s narrator for free will is called “Who’s in Charge? Free Will and the Science of the Brain.” It’s scheduled for release later this month.

Questionnaire can help with early identification of autism

May 5, 2011

A growing body of research suggests that early intervention is important for helping children with autism spectrum disorders. But early identification, which is critical for early intervention, has been somewhat elusive.

A new questionnaire, designed to be completed by parents in the pediatrician’s office during the one-year-old well-baby checkup, may help. Researchers from the University of California at San Diego had pediatricians distribute the 24-question survey to parents of 10,479 babies. The test identified 1,371 babies as potentially having autism or other developmental delay. The researchers tracked 184 of those, of whom 32 were subsequently were found to have autism spectrum disorder, 56 had language delays, 9 had developmental delays and 36 had other problems.

The survey is promising, but there was one challenge: 25% of the babies identified as potentially having developmental delays ended up on a normal development path. Such a high false-positive rate could result in a lot of unnecessary anxiety for parents.

The New York Times recently highlighted the research, which was published in the Journal of Pediatrics:

Although many pediatricians don’t screen 1-year-olds for autism, there is a growing body of evidence suggesting early intervention can be effective, said Dr. Karen Pierce, the lead author of the study — published Thursday in The Journal of Pediatrics — and assistant director of the Autism Center of Excellence at University of California, San Diego.

The checklist poses simple questions, like whether a baby responds to his or her name, whether parents can tell when an infant is happy or upset, and whether a child engages in pretend play with dolls or stuffed animals.

The impact of sleep on sustained attention

April 18, 2011

This weekend’s NY Times Magazine is all about health – everything from the toxicity of sugar to the question of whether cell phones cause cancer. One article that caught our eye (at least after a cup of morning coffee) asks “How little sleep can you get away with?

David Dinges, the head of the Sleep and Chronobiology Laboratory at the Hospital at the University of Pennsylvania has asked just this question, and the answer is: you should really try to get 8 hours. Dinges’ 2003 study assigned dozens of subjects to three different groups: some slept four hours, others six hours and others, for the lucky control group, eight hours — for two weeks in the lab. The study used a measure called psychomotor vigilance task, or PVT. PVT is a “tedious but simple if you’ve been sleeping well. It measures the sustained attention that is vital for pilots, truck drivers, astronauts. Attention is also key for focusing during long meetings; for reading a paragraph just once, instead of five times; for driving a car. It takes the equivalent of only a two-second lapse for a driver to veer into oncoming traffic.”

The results?

Those who had eight hours of sleep hardly had any attention lapses and no cognitive declines over the 14 days of the study. What was interesting was that those in the four- and six-hour groups had P.V.T. results that declined steadily with almost each passing day. Though the four-hour subjects performed far worse, the six-hour group also consistently fell off-task. By the sixth day, 25 percent of the six-hour group was falling asleep at the computer. And at the end of the study, they were lapsing fives times as much as they did the first day.

The six-hour subjects fared no better — steadily declining over the two weeks — on a test of working memory in which they had to remember numbers and symbols and substitute one for the other. The same was true for an addition-subtraction task that measures speed and accuracy. All told, by the end of two weeks, the six-hour sleepers were as impaired as those who, in another Dinges study, had been sleep-deprived for 24 hours straight — the cognitive equivalent of being legally drunk.

These results are particularly interesting in light of a study recently published in the journal SLEEP that indicated that loss of an hour of sleep per night among children with ADHD had a significant impact on their ability to remain focused and sustain attention From a Science Daily article summarizing the research: “The study suggests that even moderate reductions in sleep duration can affect neurobehavioral functioning, which may have a negative impact on the academic performance of children with ADHD.”

Results of multivariate analyses of variance show that after mean nightly sleep loss of about 55 minutes for six nights, the performance of children with ADHD on a neurobehavioral test deteriorated from the subclinical range to the clinical range of inattention on four of six measures, including omission errors (missed targets) and reaction time. Children with ADHD generally committed more omission errors than controls. Although the performance of children in the control group also deteriorated after mean nightly sleep loss of 34 minutes for six nights, it did not reach a clinical level of inattention on any of the six measures.

Reut Gruber, PhD, assistant professor in the department of psychiatry at McGill University and director of the Attention, Behavior and Sleep Laboratory at Douglas Mental Health University Institute in Montreal, Québec, quoted in the Science Daily article, has advice for parents:

“The reduction in sleep duration in our study was modest and similar to the sleep deprivation that might occur in daily life,” Gruber said. “Thus, even small changes in dinner time, computer time, or staying up to do homework could result in poorer neurobehavioral functioning the following day and affect sustained attention and vigilance, which are essential for optimal academic performance.”

“An important implication of the present study is that investments in programs that aim to decrease sleep deprivation may lead to improvements in neurobehavioral functioning and academic performance,” she said.

I don’t know about you, but we’re going to go take a nap.

It’s About Time…

March 29, 2011

Auditory processing describes what happens when the brain recognizes and interprets sounds. Humans hear when energy that we recognize as sound travels through the ear and is changed into electrical information that can be interpreted by the brain. For many students, something is adversely affecting the processing or interpretation of this information. As a result, these students often do not recognize subtle differences between sounds in words, even though the sounds themselves are loud and clear. For example: “Tell me how a chair and a couch are alike” may sound to a child struggling with auditory processing like “Tell me how a hair and a cow are alike.”

These kinds of problems are more likely to occur when the child is in a noisy environment or is listening to complex information.

The Temporal Dynamics of Learning Center (TDLC) at the University of California is one of six Science of Learning Centers funded by the National Science Foundation. Its purpose is “to understand how the element of time and timing is critical for learning, and to apply this understanding to improve educational practice.”

What is the role of timing in learning? From the TDLC Web site:

When you learn new facts, interact with colleagues and teachers, experiment with new gadgets, or engage in countless other learning activities, timing plays a role in the functioning of your neurons, in the communication between and within sensory systems, and in the interactions between different regions of your brain. The success or failure of attempts to communicate using gestures, expressions and verbal language also depend on timing.

In short, timing is critical for learning at every level, from learning the precise temporal patterns of speech sounds, to learning appropriate sequences of movements, to optimal training and instructional schedules for learning, to interpreting the streams of social signals that reinforce learning in the classroom.

Learning depends on the fine-scale structure of the timing between stimuli, response, and reward. The brain is exquisitely sensitive to the temporal structure of sensory experience:

  • at the millisecond time scale in the auditory system;
  • at the second time scale in reinforcement learning;
  • at the minute time scale for action-perception adaptation; and
  • at the day-to-week time scale for consolidation and maturation.

Each level of learning has its own temporal dynamics, and its own timing constraints that affect learning. These levels are not independent, but instead, timing constraints at one level affect learning at another level in a nested way. For example, the dynamics at the cellular level, which is often on the order of milliseconds, implement learning on the whole-brain and behavioral level on much longer time scales, including memories that last a lifetime.

The past decade of neuroscience research demonstrates that the intrinsic temporal dynamics of processes within the brain also reinforce and constrain learning. For example, we have discovered that slow learners tend to have slow “shutter speeds” in terms of how their brains take in and process information. For some poor readers, the underlying problem is the their inability to perceive fast acoustic changes in speech sounds (phonemes) that must be accurately perceived in order to learn letter-sound correspondence rules for reading.

Fortunately, says the TDLC Web site, “Neuroscience-based training regimes that improve this temporal processing ability improve both spoken and written language learning in struggling readers.”

One such training program is the Fast ForWord program, which can be an effective intervention for children with struggling with processing rates because it goes right to the cause of the problem, strengthening the gray matter in the area of the brain responsible for processing auditory information. With Fast ForWord, children are first exposed to sounds that are modified to enhance the minute acoustic differences between similar speech sounds. As children demonstrate proficiency and build new neural pathways, the program automatically reduces the level of modification, until eventually students are challenged to process normal speech sounds.

When their brains are processing speech sounds at peak efficiency, students can better  recognize and discriminate the rapidly changing sounds that are important for discriminating phonemes (the smallest units of speech that distinguish one word from another). As a result, they will more easily:

  • Attend and respond to directions and class discussions
  • Remember questions, directions, and information
  • Learn to read and become a better reader

Competing Memories

March 25, 2011

Does something like this ever happen to you?  From Yale psychologist Brice Kuhl, quoted in a NY Times article about memory:

“I park in a garage every day at work, and I park in a different space every day, depending on availability. And I very often walk to where I parked the day before. It’s not that I totally forgot where I parked, it’s just that I still remember yesterday’s spot.”

When the brain is cluttered with similar items (say a new password replacing an expired one, or a new phone number), we have difficulty recalling just one. Kuhl’s research (published in the Proceedings of the National Academy of Sciences) indicates that this difficulty is reflected in “more ambiguous” neural activation when engaged in competitive remembering as compared to “more robust” activation for non-competitive memories.

Creativity in Young Learners

March 8, 2011

Two blogs we follow have recently tackled the topic of creativity in young learners, each from a slightly different perspective:

A recent post at Sharpbrains.com features an excerpt from John Medina’s book Brain Rules for Baby that looks at the link between creativity and a certain kind of risk-taking. Medina describes “functional impulsivity”, the presence of which makes you more creative:

What ever their gender, creative entrepreneurs have functional impulsivity instincts in spades. They score atmospherically high on tests that measure risk­ taking, and they have a strong ability to cope with ambiguity. When their brains are caught in the act of being creative, the medial and orbital sectors of the pre­frontal cortex, regions just behind the eyes, light up like crazy on an fMRI. More “managerial types” (that’s actually what researchers call them) don’t have these scores—or these neural activities.

Medina is careful to differentiate functional impulsivity from, say, putting life and limb at risk on a dare, which tends to be associated not with creativity but with substance abuse.

At Scientific Learning’s Science of Learning blog, the topic of creativity is focused on the books of Edward de Bono, who proposes methods for teaching students to think creatively and “create context from nothingness.”

In one example, he describes how a teacher shows his students a photo of people dressed in street clothes wading through water at a beach. The teacher then asks the students to come up with interpretations as to what is going on in the picture. The teacher has de-emphasized the context; the crux of the activity is to develop the context using their imaginations.

In this situation, de Bono says that students might respond by saying that the picture shows a group of people caught by the tide, or a group crossing a flooded river, or people wading out to a ferry boat which cannot come to shore, or people coming ashore from a wrecked boat.

The fact that the photo is actually of a group of people protesting at a beach is completely irrelevant. The author stresses that the right answer is not important; generating as many interpretations as possible is. The teacher has created a safe, controlled environment and activity where students are encouraged to think outside the box and exercise creative habits of mind, free from qualitative judgment. He even goes on to suggest that if a student comes up with a particularly unfeasible interpretation, the teacher should not judge, but continue to question the student until the context for the interpretation becomes clear, encouraging cultivation of the student’s creative skill.

Medina’s books on the neuroscience of development differentiate between the “seeds”, which is what a child is born with, and the “soil” which is what parents and others can do to nurture that raw material. These two posts, taken together, indicate that when it comes to creativity, both play a role.

TED Talk on the Linguistic Genius of Babies

February 17, 2011

In this great 10-minute lecture, Patricia Kuhl, co-director of the Institute for Brain and Learning Sciences at the University of Washington, shares her findings about how babies learn one language over another — by listening to the humans around them and “taking statistics” on the sounds they need to know.

Experiments and brain imaging show how 6-month-old babies use sophisticated reasoning to understand their world. Dr. Kuhl’s work has played a major role in demonstrating how early exposure to language alters the brain. It has implications for critical periods in development, for bilingual education and reading readiness, for developmental disabilities involving language, and for research on computer understanding of speech.

Brain vs. Mind

December 13, 2010

Several years ago, a colleague recommended M. Mitchel Waldrop’s book Complexity: The Emerging Science at the Edge of Order and Chaos. I’m not going to do justice to the, well, complexity, of complexity theory, but my two takeaways were that:

  • Incredibly complex systems can emerge very quickly from very basic rules or parameters. Think of birds flying in formation, who encounter an obstacle like a sky scraper and can quickly re-assemble their formation on the other side, guided only by rules that govern their relationship to the bird in front of them.
  • Laboratory experiments where scientists remove variables in order to get to a “core” phenomenon may be of little utility, since no physical process occurs in such isolation in nature.

Mentioned in Waldrop’s book is the Santa Fe Institute, a non-profit institute that supports complex systems research. From the Institute’s Web site:

Complex systems research attempts to uncover and understand the deep commonalities that link artificial, human, and natural systems. By their very nature, these problems transcend any particular field, for example, if we understand the fundamental principles of organization, we will gain insight into the functioning of cells in biology, firms in economics, and magnets in physics. This research relies on theories and tools from across the sciences. Part of the rise of the complex systems research agenda can be tied to the use of theoretical computation as a new way to explore such systems.

Legend has it that the founders of Scientific Learning (creators of the Fast ForWord programs), Drs. Michael Merzenich and Paula Tallal, met at the Santa Fe Institute. Merzenich, a neuroscientist, had been doing groundbreaking research into brain plasticity, while Tallal, a neuropsychologist, focused on language acquisition. Their combined work leveraged their expertise in both fields, and created a revolutionary program with a reach that far exceeds that of their individual research.

I don’t know if he would consider himself a complexity theorist, but an essay by Andy Clark, professor of logic and metaphysics in the School of Philosophy, Psychology, and Language Sciences at Edinburgh University, Scotland, evoked the kind of multi-dimensional and multi-disciplinary thinking that inspired the creation of Fast ForWord. Clark’s essay takes a shot at recent brain research (which sometimes appears to consist entirely of fMRI brain scans):

We are all familiar with the colorful “brain blob” pictures that show just where activity (indirectly measured by blood oxygenation level) is concentrated as we attempt to solve different kinds of puzzles: blobs here for thinking of nouns, there for thinking of verbs, over there for solving ethical puzzles of a certain class, and so on, ad blobum.

While supporting this kind of research (“Some of my best friends are neuroscientists and neuro-imagers” says Clark), he does ask an interesting question:

Is it possible that, sometimes at least, some of the activity that enables us to be the thinking, knowing, agents that we are occurs outside the brain?

Clark definitely stretches the concept of “outside the brain.” For example, he points to hand waving (those wild gesticulations many of us make while talking) and studies that show that individuals perform more poorly on mental tasks when their ability to gesticulate is limited, or that “the use of spontaneous gesture increases when we are actively thinking a problem through, rather than simply rehearsing a known solution.” But Clark also points to personal devices, like the iPad, which, he argues “transform and extend the reach of bare biological processing in so many ways.”

Clark’s essay is a great read on this concept of embodied cognition. His conclusion, which sounds like it could come straight from the Santa Fe Institute, is that while the brain itself is incredible, “we — the human beings with versatile bodies living in a complex, increasingly technologized, and heavily self-structured, world — are more fantastic still.” And that understanding the mind is more than just understanding the brain.

Good News For Control Freaks!

December 7, 2010

So screams the first line of a recent article on Science Daily. What’s the good news? A study, published in the journal Nature Neuroscience, shows that “having some authority over how one takes in new information significantly enhances one’s ability to remember it.”

The study compared active and passive learning in a novel way: participants were presented with an array of objects to be memorized, masked by a gray screen. A “viewing window” allowed the study participants to see one object at a time. To test active learning, the participants were able to control the window using a computer mouse. Passive learners viewed a recorded version of the viewing made by an earlier active learner.

The study found significant differences in brain activity in the active and passive learners. Those who had active control over the viewing window were significantly better than their peers at identifying the original objects and their locations.

Cool enough, but to get to a neurological explanation for the phenomenon, the researchers repeated the study with individuals with amnesia (the impaired ability to learn new things) as a result of damage to the hippocampus (the portion of the brain responsible for many memory-related functions). For these participants, there was no difference in recall between active and passive learning.

Additionally, brain imaging of healthy participants indicated that:

Hippocampal activity was highest in the active subjects’ brains during these tests. Several other brain structures were also more engaged when the subject controlled the viewing window, and activity in these brain regions was more synchronized with that of the hippocampus than in the passive trials.

We’re not so sure what to make of the neurological findings in the study, but the clear differences between active and passive learning have lots of relevance for education. It explains why television makes a lousy teaching tool, and why actively engaging students in reading (for example, stopping to ask them questions about what they’ve just read or what they expect to happen next) is helpful for students.


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