Sounding Off

Autism is defined, described, explained in many and various ways (indeed---what's your top way of answering the "what is autism?" question?). And here's another way to answer the question:

Autism involves "problems in comprehending auditory signals" according to the author of a new study in the June Nature Neuroscience about how the human brain processes speech and language. Josef Rauschecker of the Georgetown University Medical Center and Sophie Scott of University College London have found that, in both humans and non-human primates, speech is processed in the brain "along two parallel pathways, each of which run from lower- to higher-functioning neural regions," as noted in a Medical.Net review. Further, both pathways begin with the processing of speech in the auditory cortex.

While the study is looking specifically at how the brain functions, I was curious about Rauschecker's specific mention of autism and the processing of auditory signals. He says:

"Understanding speech is one of the major problems seen in autism, and a person with schizophrenia hears sounds that are just hallucinations......Eventually, this area of research will lead us to better treatment for these issues.

"But mostly, we are fascinated by the fact that humans can make such exquisite sense of the slight variation in sound waves that reach our ears, and only lately have we been able to model how the brain knows how to attach meaning to these sounds in terms of communication." he says.

We've long observed that "something happens" between Charlie hearing sounds and his mind translating them into meaning. It's been established that his hearing is fine. Understanding speech---the spoken word---has long confounded Charlie, and he also struggles a great deal to use speech himself. But music (including the human voice singing) is a completely different matter for Charlie. He's always been attentive to the tone, rhythm, pitch of the human voice (more so than to individual words, we've observed), and to sounds (including those made by inanimate objects like the garage door opener and the microwave oven).

And then a couple of months back Charlie was repeatedly making some sort of coughing noise (whether he had to cough or not) and, on one of our afternoon walks, he made the noise and someone responded.

A Canadian goose.

(Guess who was more startled to hear another species in an exchange of sounds?)

See the complete abstract by clicking "read more."

From Nature Neuroscience:

Speech and language are considered uniquely human abilities: animals have communication systems, but they do not match human linguistic skills in terms of recursive structure and combinatorial power. Yet, in evolution, spoken language must have emerged from neural mechanisms at least partially available in animals. In this paper, we will demonstrate how our understanding of speech perception, one important facet of language, has profited from findings and theory in nonhuman primate studies. Chief among these are physiological and anatomical studies showing that primate auditory cortex, across species, shows patterns of hierarchical structure, topographic mapping and streams of functional processing. We will identify roles for different cortical areas in the perceptual processing of speech and review functional imaging work in humans that bears on our understanding of how the brain decodes and monitors speech. A new model connects structures in the temporal, frontal and parietal lobes linking speech perception and production.