پژوهشگران توانسته اند به روش شگفتی آوری برای رمزگشایی از امواج مغزی دست یابند و واژه ها را بر پایه این امواج در مغز بیمارانی که آن واژه ها را در ذهن خود فکر می کردند بازسازی نمایند.

این روش که در آخرین شماره "پلوس – بیالوژی" گزارش شد بر امواج  الکتریکی که مستقیما از مغز بیماران گردآوری می شود تکیه دارد.  بر اساس علایم مغزی بیمار شنونده، یک مدل رایانه ای صدای واژه هایی که بیمار به آنها فکر می کرد را بازسازی نمود.

این روش در آینده ممکن است به بیماران در وضعیت بیهوشی/اغما و آنانی که در خود قفل شده اند در جهت برقراری ارتباط کمک کند.

چند رویکرد در سال های اخیر چنین القا کرده است که دانشمندان دارند به روش هایی نزدیک می شوند که بتوانند به درون اندیشه های ما دسترسی یابند.

شرکت کنندگان در مطالعه ای در سال 2011، برای نمونه، توانستند از طریق الکترودهایی که به مغز آنها متصل شده بود یک مکان نما (کرسر) را فقط با فکر کردن به کلمه های صدادار حرکت دهند.

روش دیگری با استفاده از اف.ام.آر.آی. و ردگیری جریان خون در مغز این انتظار را ایجاد کرده است که بتوان واژه ها و یا ایده هایی که کسی به آنها فکر می کند را شناسایی نمود.

گروه جک گالانت در دانشگاه کالیفرنیا در برکلی با مطالعه الگوهای جریان خون مرتبط با تصویرهای مشخصی نشان داد که با این الگوها می توان حدس زد که فرد به چه تصویرهایی فکر می کند و به یک عبارت "فیلم در ذهن" را بازسازی نمود.

اکنون، برایان پالسی از دانشگاه کالیفرنیا در برکلی و تیم همکارانش طرح "بازسازی محرک ها" را گامی پیش تر برده اند.  دکتر پالسی در این باره گفت: "این [پژوهش ما] تا حد زیادی از کار جک [گالانت] الهام گرفته است.  یک پرسش این بود ... که با استفاده از مدل رویکردی مشابهی، ما تا چه اندازه می توانیم وارد سامانه شنوایی شویم؟"

این تیم بر روی منطقه ای از مغز که ابر شکنج گیجگاهی یا اس.تی.جی. نامیده می شود تمرکز کرد.

این منطقه وسیع تنها بخشی از آلت شنوایی نیست، بلکه یکی از بخش های "مرتبه برتر" مغز است که به ما کمک می کند تا صداهایی را که می شنویم از نظر زبانی درک نماییم.

تیم پژوهشگران امواج مغزی اس.تی.جی. 15 بیمار که تحت عمل جراحی برای صرع و یا غده سرطانی بودند را، در حالی که چند گوینده مختلف واژه ها یا جمله هایی را برایشان می خواندند، پایش نمود. [ادامه در زیر ...]

[علاوه بر گزارش بخش علمی سرویس جهانی بی.بی.سی. در زیر، گزارش مفصل تری در این باره نیز به نقل از سایت "پاپیولار ساینس" در پایین تر آمده است.  شما همچنین با مراجعه به سایت "پاپیولار ساینس" می توانید صدای واژه های بازساری شده را نیز بشنوید. ]

Science Decodes 'Internal Voices'

By Jason Palmer Science and technology reporter, BBC News | 31 January 2012

Researchers have demonstrated a striking method to reconstruct words, based on the brain waves of patients thinking of those words.

The technique reported in PLoS Biology relies on gathering electrical signals directly from patients' brains.

Based on signals from listening patients, a computer model was used to reconstruct the sounds of words that patients were thinking of.

The method may in future help comatose and locked-in patients communicate.

Several approaches have in recent years suggested that scientists are closing in on methods to tap into our very thoughts.

In a 2011 study, participants with electrodes in direct brain contact were able to move a cursor on a screen by simply thinking of vowel sounds.

A technique called functional magnetic resonance imaging to track blood flow in the brain has shown promise for identifying which words or ideas someone may be thinking about.

By studying patterns of blood flow related to particular images, Jack Gallant's group at the University of California Berkeley showed in September that patterns can be used to guess images being thought of - recreating "movies in the mind".

All in the mind

Now, Brian Pasley of the University of California, Berkeley and a team of colleagues have taken that "stimulus reconstruction" work one step further.

˝The development of direct neuro-control over virtual or physical devices would... improve quality of life immensely for those who suffer from impaired communication skills”  Mindy McCumber Florida Hospital

"This is inspired by a lot of Jack's work," Dr Pasley said. "One question was... how far can we get in the auditory system by taking a very similar modelling approach?"

The team focused on an area of the brain called the superior temporal gyrus, or STG.

This broad region is not just part of the hearing apparatus but one of the "higher-order" brain regions that help us make linguistic sense of the sounds we hear.

The team monitored the STG brain waves of 15 patients who were undergoing surgery for epilepsy or tumours, while playing audio of a number of different speakers reciting words and sentences.

The trick is disentangling the chaos of electrical signals that the audio brought about in the patients' STG regions.

To do that, the team employed a computer model that helped map out which parts of the brain were firing at what rate, when different frequencies of sound were played.

With the help of that model, when patients were presented with words to think about, the team was able to guess which word the participants had chosen.

They were even able to reconstruct some of the words, turning the brain waves they saw back into sound on the basis of what the computer model suggested those waves meant.

"There's a two-pronged nature of this work - one is the basic science of how the brain does things," said Robert Knight of UC Berkeley, senior author of the study.

"From a prosthetic view, people who have speech disorders... could possibly have a prosthetic device when they can't speak but they can imagine what they want to say," Prof Knight explained.

"The patients are giving us this data, so it'd be nice if we gave something back to them eventually."

The authors caution that the thought-translation idea is still to be vastly improved before such prosthetics become a reality.

But the benefits of such devices could be transformative, said Mindy McCumber, a speech-language pathologist at Florida Hospital in Orlando.

"As a therapist, I can see potential implications for the restoration of communication for a wide range of disorders," she told BBC News.

"The development of direct neuro-control over virtual or physical devices would revolutionise 'augmentative and alternative communication', and improve quality of life immensely for those who suffer from impaired communication skills or means.

Translating Brain Waves to Reconstruct Sounds and Conversations You've Heard

Researchers see a way to eavesdrop on our brains

By Rebecca Boyle | Popular Science | Posted 01.31.2012

As you listened to your colleagues’ conversations at work today, or to a podcast on the train home, or to your personal trainer shouting lift, your brain completed some complex tasks. The frequencies of syllables and whole words were decoded and given meaning, and you could make sense of the language-filled world we live in without actively thinking about it. Now a team of researchers from the University of California at Berkeley has figured out how to map some of these cortical computations. It’s a major step toward understanding how we hear — and a possible step toward hearing what we think.

By decoding patterns of activity in the brain, doctors may one day be able to play back the imagined conversations in our heads, or to communicate with a person who can think and hear but cannot speak.

Brian Pasley and colleagues at UCB worked with 15 volunteer patients who were being treated for epilepsy. The team also included researchers from UCB, UC San Francisco, the University of Maryland and The Johns Hopkins University. To diagnose the seizures’ places of origin, surgeons implanted electrodes directly onto the patients’ brains, providing a rare opportunity to study electrical signals in various brain regions. Pasley said the research team visited patients in their hospital rooms and played them recorded words while monitoring activity in the superior temporal gyrus, a region of the auditory cortex.

“We’re looking at which brain sites become active. Because we can determine some association between those brain sites and different frequencies, we can watch what brain sites are turning on and off for these recordings, and that lets us map back to the sound,” he said.

Since neurologists can know the frequencies of certain phonemes — specific language sounds — this cortical spectroscopy can decode which sounds, and then perhaps which words, a person is hearing. Pasley compared it to piano playing: “If you’re an expert pianist, you know what musical notes are associated with each piano key, and you understand that relationship between the key and the sound,” he said. “If you turn the sound off, and have the pianist watch which piano keys are being pressed, this expert would have an idea what sound is being played even though they can’t hear anything.”

The patients would hear a single word or a single sentence that would fall in the range of normal speech, between 1 and 8,000 Hz, Pasley said. Words were spoken by people of both genders and a wide range of voice frequencies. As they listened, the patients’ brain activity was recorded. Then Pasley developed two computational models that crunched the electrode recordings and would predict the word being heard. One of the two methods could create a reproduced sound so close to the original word that Pasley and his colleagues could guess what it was 90 percent of the time, he said.

“It’s not intelligible, but you can identify some similarities,” he said. Watch the video below to hear what he means.

Neuroscientists have long been trying to decode the inner workings of the brain, associating neurons in the sensory cortices with stimuli that fire up those neurons. But the newest research, along with this paper, peers more deeply into the recesses of our minds, promising to illuminate thoughts so they can be seen and shared with others.

In December, Boston University researchers published research explaining how they stimulated patients’ visual cortices and induced brain patterns to create a learned behavior, even when the subjects did not know what they were supposed to be learning. Last fall, Jack Gallant — also at UCB — published a paper describing the reconstruction of video images by tapping the visual cortices of people who watched the videos.

This form of mind-reading, which neurologists prefer to call “decoding,” is a long way from everyday use. And there are clearly some ethical questions surrounding its use (although it would be hard to implant electrodes to peep in on an unwilling person). But there are some practical, medically motivated reasons to do these things, like communicating with locked-in patients, or those who have lost the ability to speak because of a stroke or a degenerative muscle disease. That depends on some other vagaries of the brain that are still not well understood, Pasley said. Development of neural prostheses depends on the assumption that brain activity is the same during real experiences and imagined ones.

“There is some evidence that when people imagine visual stimuli or sound stimuli, some of the same brain areas do seem to activate as when you are actually looking at something or hearing something,” he said. “But we didn’t have a good idea at all, even if the same areas are activating, if they are processing the same way, and using the same rules, as during perception.”

In this study, the researchers only focused on English words and phonemes, but Pasley would like to study other languages too, he said. The paper appears in the journal PLoS Biology.