Tag Archives: brain areas

Electrodes in an epilepsy patient's brain (shown here in magnetic resonance imaging) revealed strikingly different patterns of activity in the articulation of consonants and vowels. (c) Nature

How the brain tackles tongue-twisting words and why it’s important

tonguetwister

Can you imagine an imaginary menagerie manager imagining managing an imaginary menagerie?

Sorry about that folks – that was a bit twisted right? Just earlier you’ve used your  lips, tongue, jaw and larynx in a highly complex manner in order to render these sounds out loud. Still, very little is known of how the brain actually manages to perform this complex tongue twisting dance. A recent study from scientists at University of California, San Francisco aims to shed light on the neural codes that control the production of smooth speech, and in the process help better our understanding.

Previous neural information about the vocal tract has been minimum due to insufficient data. However, recently a team of US researchers have performed the most sophisticated scan of its kind, down to the millimeter and millisecond scale, after they  recorded brain activity in three people with epilepsy using electrodes that had been implanted in the patients’ cortices as part of routine presurgical electrophysiological sessions.

As you might imagine, huge amounts of data were outputted. Luckily, the researchers developed a complex multi-dimensional statistical algorithm to filter out information so that they could reach that referring to how neural building blocks  combine to form the speech sounds of American English.

Electrodes in an epilepsy patient's brain (shown here in magnetic resonance imaging) revealed strikingly different patterns of activity in the articulation of consonants and vowels. (c) Nature

Electrodes in an epilepsy patient’s brain (shown here in magnetic resonance imaging) revealed strikingly different patterns of activity in the articulation of consonants and vowels. (c) Nature

First of all, the researchers found that neurons fired differently when the brain was prompted to utter a consonant than a vowel, despite the parts of speech “use the exact same parts of the vocal tract”, says author Edward Chang, a neuroscientist at the University of California, San Francisco.

The team found that the brain seems to coordinate articulation not by what the resultant phonemes sound like, as has been hypothesized, but by how muscles need to move. Data revealed three categories of consonant: front-of-the-tongue sounds (such as ‘sa’), back-of-the-tongue sounds (‘ga’) and lip sounds (‘ma’). Vowels split into two groups: those that require rounded lips or not (‘oo’ versus ‘aa’).

“This implies that tongue twisters are hard because the representations in the brain greatly overlap,” Chang says.

Even though the study has a very limited sample size of participants, and diseased on top of it, their findings provide nevertheless some invaluable information on a subject all too poorly studied. There are a lot of people who are suffering from speech impairments, either as a result of accidents resulting to the damage to the brain or the all too common strokes.

“If we can crack the neural code for speech motor control, it could open the door to neural prostheses,” Hickok says. “There are already neural implants that allow individuals with spinal-cord injuries to control a robotic arm. Maybe we could do something similar for speech?”

Findings were published in the journal Nature.

Math Headache

Math anxiety is similar to experiencing physical pain, brain study finds

Math HeadacheFor many of us, mathematics comes with a feeling of anxiety, not while actually performing math, but beforehand in anticipation. Why some people dread math is an interesting question that deserves a systematic, scientific answer – some other time, however. Recently, I came about an equally interesting study, that analyzed how the brain perceives the fear of math. The findings showed that the anxiety experienced in anticipation of math is associated with the experience of physical pain.

Mathematics has only evolved as a distinct branch of study available to the masses a few centuries ago. Actually, only in the past 150 years or so following education reforms that spurred in Europe did mathematics and its concepts become widely introduced to the public. Society has benefited a great deal from wide spread mathematical knowledge, despite most of its students loathed it. It’s rather clear then that the human brain hasn’t evolved a specialized brain structure dedicated to math anxiety and that the same feeling must come from some other brain function associated with this fear.

To find out which part of the brain is responsible for math anxiety, psychologists devised a series of questions, which they named Short Math Anxiety Rating-Scale, or SMARS. The study volunteers, 28 in total, had to answer these question while a MRI brain scan was performed at the same time. The quizzes were math related in part, while others were focused on verbal skills. Their actual performance was of little significance for the researchers, however – what they were looking at was anxiety.

In order to trigger anxiety, the scientists flashed some colours that warned the participants that math question was following (yellow circle). To fight off extraneous signals, the psychologists managed to pinpoint the differences between people experiencing discomfort while performing math and those while anticipating math. This allowed them to correct their results accordingly.

At the end of their study, the researchers found a limited number of brain regions associated with the math anxiety, the strongest signals coming from the bilateral dorso-posterior insula, an area deep in the core of the brain. The researchers showed when anticipating an upcoming math-task, the higher one’s math anxiety, the more one increases activity in this region of the brain. On the contrary, when getting signaled that a word test was coming, participants actually dropped activity in the insula by a significant margin.

This region of the insular has been documented in the previous studies to be associated with the experience of physical pain. Actually, it’s quite possible to induce the experience of pain simply by stimulating the insula.  Interestingly, this relation was not seen during math performance, suggesting that it is not that math itself hurts; rather, the anticipation of math is painful.

Also, the authors of the study recently published in the journal PLoS one have also confirmed that math anxiety is linked with poor math performance when answering the questions. The value the study provides is that it might explain why people with high anxiety and little tolerance for math behave this way, stirring them away from taking math classes or even entire math-related career paths.

Short-term memory

Expand short-term memory through exercises

Short-term memoryThe average brain can only hold about five to seven pieces of information at a time within 30 seconds – this is called working memory. What people usually do to get pass the 30 seconds interval is they re-expose themselves to the information, for instance if you want to remember a 7 digit phone number (seven pieces of information) you’ll have to constantly play the sequence inside your head. Through repetition, you’ll be able to move it away from your working memory to some extent.

But, how can you increase you short-term memory capacity in general? What if you could go from remembering the names of the last 5 people you just met to 10 names? Would short-term memory improvement have any effects on other cognitive senses? These questions and more or less satisfying answers can be found in a recently published study by Jason Chein at Temple University in Philadelphia, Pennsylvania.

Past attempts to expand short-term memory implied specific strategies, such as rehearsing long strings of numbers, often improved their performance on the particular task at hand, but with no visible long-term effects on the memory. Chein’s training technique is different and most importantly turns results – a software  asks people to answer questions about a string of successive sentences while simultaneously remembering the last word of each sentence. It is very difficult to develop conscious shortcuts to deal with the two conflicting sources of information, so the brain is forced to make more long-lasting changes.

The technique reportedly works amazingly, with a whooping 15 per cent improvement over a training course of five weeks, meaning expanding your working memory from seven to eight items. While it’s evident that short-term memory improvement is possible, scientists argue whether it has any implications on other cognitive areas – some say it doesn’t have any connections, while others stress that cognitive abilities from logical reasoning and arithmetic to verbal skills and reading comprehension are directly linked to the working memory.

As published in Psychonomic Bulletin & Review.

Touch and sight – more connected than previously thought

What you see may be very much related to what you’ve just felt. Even though we were taught at school that each sense is processed in another area of the brain it seems that this theory may be wrong and that there is a lot more to understand about the way human brain works.

As an example, a light ripple of pins moving up the fingertip tricked the subjects of a study into perceiving some lines moving on a screen as moving down, and the other way around. So, there is something going on.

Some recent studies have proved that the way our brain works –  in this case processes the most important senses – is far more complex than thought for decades. Firstly, it was discovered that hearing and seeing are related to each other, but now it seems that this is far from being the end of the story.

In order to take the theory even further, a trick of perception named aftereffect was used by scientists, a phenomenon that occurs for example when watching a waterfall. Staring at it for some time will eventually make one perceive the stationary rocks as moving up. This happens because the neurons which are in charge of the “down” get tired while the “up” ones are still fresh and create this impression.

But what interested the researchers was the aftereffect caused by the sense of touch. A small gadget of the size of a stamp made of 60 pins in rows was used throughout the study as the participants were asked to rest a finger on top of it. Some of the rows were raised at different times, thus creating a gentle prodding movement which was directed away or toward the person, for ten seconds. Then, the subjects were asked to look at a computer screen on which they could see common patterns of white and black horizontal lines. The lines were constantly moving and switching places, but their entire movement could be characterized as upward or downward.

Simple task, isn’t it? Well, not when the brain has a lot of stimuli to cope with. This is why the subjects who had felt the lines on the little device going up perceived the lines on the screen as going down and the other way around. This is the the visual aftereffect. A touch aftereffect can also be induced as watching lines going up on a screen made the participants feel the pins as going down.

Now it seems quite clear that sight and touch are connected to a larger extent than it was expected. Now, the next step is to find where exactly in the brain the connection is created.

source: Body & Brain