Sensory integration

This garden universe vibrates complete. Some we get a sound so sweet. Vibrations reach on up to become light, and then thru gamma, out of sight. Between the eyes and ears there lay, the sounds of color and the light of a sigh.  ~   Moody Blues

   

A recent study shows that baboons can learn to tell the difference between word and non-word strings [ link ]. In an accompanying editorial, Dr Michael Platt says this evidence suggests dyslexia might be more of a visual problem than a problem matching sounds to letters. It’s a rare opportunity that I get to hear a neuroscientist jump to an either-or conclusion like that. Reading is an integrated process that coops many areas of the brain. A problem in the visual system can produce a reading deficit just as profound as a problem in the auditory system. These systems are integrated by higher centers of the brain during reading. What these investigators discovered with baboons is a better example of pattern recognition. It’s a process shared by any species that survives in the wild. Over time, the visual system is tuned to distinguish what’s meaningful from what isn’t by a process of ‘statistical regularity’. Statistical regularity simply means that certain signal combinations appear more frequently with meaningful objects than with non-meaningful objects. It’s no surprise that a baboon can perform this with a string of letters just as easily as it can a set of racing stripes. And I have no doubt that humans require a working visual system as well as a sound system to be able to read coherently. The written word hasn’t been around long enough to evolve an area of it’s own in the brain like it has for speech and vision.

 

Heartbreak beat

       

Heartbreak Beat~Psychedelic Furs

Most children I see with dyslexia don’t have problems with vision. What they have is a slight gap somewhere in their auditory system, or sense of hearing. They cannot translate the word they see on the page to the sound of a word in memory. Until they can do that .. it’s hard for them to recognize the word as something they’ve heard before. I have a theory. I believe that the first language we learn is the sound of our mother’s heart beat. It serves as an internal metronome ..setting the tempo that helps us follow the sound of speech. It marks the onset of phonemes and syllables, which then helps us identify words and sentences. Dr Oliver tells me that his stroke patients who lose their ability to speak can still sing. When they begin putting their words into a melody ..they can express themselves fluently. My friend Levi has MS. He uses music as a prosthesis. He my not be able to walk the same as he used to, but he can dance every bit as good. He thanks his early years spent at Grateful Dead concerts for that. What this suggests to me is that ‘keeping the beat’ may be a more fundamental process than learning to read or understand speech. So I’ve been pushing the envelope of my heartbeat theory ..to the annoyance of those around me. I’ve come to believe that the heartbeat we hear in the womb sets up an internal rhythm that helps us follow events for the rest of our lives. Without it ..everything we hear and see would simply appear as though they were coming out of nowhere ..then vanish into nowhere ..without coherence ..nothing helping us string them together.

Dyslexia

Voice recognition involves perceiving differences in the way people speak. Individuals with dyslexia, however, cannot do this. The problem is a slight auditory impairment. They can understand perfectly well what others are saying and who is speaking. They’re just not as sensitive to subtle phonic variations between speakers. 

A study by Tyler Perrachione at MIT [link] reaffirms the theory that the underlying deficit in dyslexia is about processing the sound of what’s written, not about seeing what’s written. They took it a step further and discovered a link between reading difficulty and the social ecology surrounding spoken language. Individuals with dyslexia have difficulty hearing consistent properties of speech within speaker as well as differences between speakers. “Lots of research has shown that individuals with dyslexia have more trouble understanding speech when there is noise in the background” says Perrachione. “These results suggest that part of the problem may be trouble following a specific voice.”

They took it another step further and found something that I find interesting. Individuals without dyslexia have the same difficulty hearing phonic variation between speakers in their second language (Mandarin Chinese) as dyslexics do between speakers in their native language. This corroborates my observation that children, without dyslexia, often perform at the same level as children with dyslexia when they are being taught to read for the first time in a foreign language. They don’t have the ‘phonic background’ necessary to identify the phonetic compounds of words. I believe this puts children from non-English backgrounds at a disadvantage when learning to read in English-speaking schools [link]

Neural regenerative training

“The number and size of neural-pathways and the integrity of myelination are important for rapid conduction in the nervous system. They are especially important for the accurate coding and transmission of speech signals.” ~ Dr Paula Tallal (left)

Continued from a previous entry ~> [link]  I leave Esalen and head north on Highway One to UC San Francisco where Paula Tallal and Mike Merzenich are developing neural retraining programs for dyslexia. I have to admit that it felt a little surreal being here after spending 14 days on the Big Sur coast. But I’m thankful to Portia for giving me this opportunity. Anyway, I listen as they explain how dyslexia is caused by “ ..under-developed neural-connections in the auditory system.” [link]. This makes it difficult for children to detect “..the subtle cues that signal the onset of phonemes.” Phonemes are the shortest and most ephemeral units of speech. They require high-speed network-connections to detect. Although they may not be as important for speech recognition ..phonemic awareness is definitely required for reading comprehension. This is especially true when children are trying to decipher words for the first time. They tell me that, by testing children’s’ ability to recognize properties of speech, it is now possible to detect dyslexia as early as the first year of life. Well ahead of reading instruction. They have developed a training program that can re-activate the growth of neuro-pathways for phonemic awareness. They have found that intervention later in life can also help regenerate neural growth if the training approximates the early learning environment of a child. In other words, neuro-regenerative training can be successful through adolescence and possibly adulthood if it is presented in a manner that’s both socially interactive and engaging

Training: They have developed a program of intense ‘sensory discrimination’ training to re-activate neural-growth. Training begins by presenting phonemes in an exaggerated manner. This means they sound louder, last longer and arrive farther apart than phonemes in regular speech. During a typical training session, they ask students to identify which phoneme they recognize from a series they’d previously heard. As students progress, the phonemes are softened, shortened and presented at a rate that more closely resembles the flow of speech. To make it both engaging and rewarding, they hosted training on an interactive computer game. Improvements were verified using standard reading tests and brain imaging. MRI scans actually showed progressive differentiation of neurons in the language centers of the brain [link]. I was stoked (because I’m weird like that). However, the next question I have to ask is whether or not these results hold-up outside the lab, where events in life can quickly overtake the best-laid plans of neuroscience practitioners.

to be continued ..

Neural regenerative training

Dr Patricia Kuhl

I met Portia Iversen while attending a writing workshop at the Esalen Institute in November, 2003. She was a screenwriter by day ..and a neuroscientist by night. I mean she would literally launch web crawlers overnight to see what research they found by morning that might help her son Dove who was somewhere on the spectrum of autistic disorders. When she discovered how little information there was, she started a foundation that awarded grants for research in the neurobehavioral sciences. The money came from the Hollywood movie industry, of which she was a member, and grants were awarded in the millions of dollars to research centers across the country that met two criteria: 1) they must have a reputation for working on developmental disorders and 2) they must be investigating neuro-regenerative practices. Needless to say, she got their attention. Universities around the country started ramping-up their labs to find techniques to help children suffering from either autism, dyslexia or attention deficit with the belief that these may not be discreet afflictions, but may fall somewhere on a distribution of early developmental imbalances. Today Portia is not only a screenwriter, but an author and member of the National Institute of Health. Her story is definitely worth reading [link].  Later at the lodge, she hands me a journal article and asks me to come up to speed so I could help her screen applicants. This led to a three-year collaboration where I learned about groundbreaking research in the neurosciences that literally blew me away. Since this is my first record of events, I’m going through my notes and starting from the beginning .. with the journal article Portia handed me.

Kuhl (2003) Foreign language experience in infancy [link]: It is generally accepted that phonemic awareness is ‘tuned’ by a child’s native language during the first year of life [link]. Initially we are capable of discerning differences between phonemes over a wide range of languages (known as the principle of equipotential). By the end of the first year however, the neural-pathways responsible for discerning native phonemes get established; and the pathways for discerning foreign phonemes, not available in the child’s verbal environment, get ‘pruned away’ by a process called juvenilization [link]. Language development is clearly an expression of the interaction between embryonics and environment outside the womb.

Findings: Dr Patricia Kuhl discovered that short-term exposure to foreign languages at nine months can significantly re-juvenilize areas of the child’s developing brain and help them retain the neuro-pathways for foreign phonemes (in this case English and Mandarin Chinese). Early language intervention can significantly alter the development of a child’s speech perception.

Naturalistic observation: Dr Kuhl cites evidence of neuro-plasticity in the wild. Zebra-Finches can be sufficiently influenced to override the innate preference for songs of their own species and learn the songs of a ‘foster’ Bengalis Finch that nurtured them.

Dyslexia: There is growing evidence to support the view that dyslexia starts out as an imbalance in the development of the auditory system. Neural pathways for phonemic awareness do not fully develop. Although it may not be severe enough to interfere with ordinary speech perception ..it can present problems with reading comprehension later in life [link]. Dr Kuhl cites studies being done at UC San Francisco that show intervention techniques that can: 1) enhance childhood auditory-development and 2) provide neuro-retraining exercises for later remediation [link] and [link].

continued ~> [link]

In a heartbeat

The rhythm of music is my prosthetic for balance. I don’t have a preference ..just whatever moves me at the time. In fact, I find dancing easier than walking ..that’s probably why I go to the drum circle at the park every chance I get. Following a rhythm has helped me learn to walk again ..just as it helped me learn to ski when I was a kid. It puts me in motion so I don’t have to think about every step ..or anticipate every move. I suppose I have my early experience to thank for that ..those teenage years spent at rock concerts. Dr Oliver tells me that stroke victims, people who have lost the ability to speak ..can still sing. When they begin putting their words into a melody ..they can express themselves fluently. What this tells me is that ‘keeping the beat’ is a deeper, more fundamental process, than constructing sentences.

Turns out that most children with dyslexia don’t have a problem with vision. What they have is a gap in their auditory system ..they cannot identify the sound of the words they see ..and until they can do that .. it’s hard to progress much further. That’s why we have to go back and treat dyslexia using auditory training. Now, I don’t know what the church of scientology thinks about this .. I can’t find any of their literature ..only proclamations made by Tom Cruise. But according to Dr Goswami [link] the first language we learn is the sound of our mother’s heart beat. It’s like an internal metronome ..setting the tempo that helps us follow the sound of speech during early childhood. Lately I’ve been pushing the boundaries of my theory ..to the annoyance of those around me. I’ve come to think of it as the rhythm that helps us follow the events in our life. Without it ..everything we see and hear would simply appear as though they were coming out of nowhere ..and disappearing into nowhere. No coherence ..nothing helping us string them together.

In a heartbeat

Many children with dyslexia cannot keep up with the flow of text fluently enough to convert symbols into sound ..then sound into meaning. To read OK, the brain has about 40 milliseconds to do this. For children with reading difficulties, this may take as many as 500 milliseconds. According to Usha Goswami [link] part of the problem may be caused by difficulty in perceiving the rhythm of speech. Goswami and her colleagues discovered that dyslexic children could not track the beat in speech. The ability to detect a beat matters when the brain is trying to process syllables and phonemes. Like a metronome, it helps children pick-up the properties of speech in time. They inform me that the ability to keep the beat is so fundamental; the first language we learn is our own mother’s heartbeat.