Basic conversation

Conversing is one of the most human things we do and we do it a great deal.  Our brains have evolved with special channels in and out for language.  Most people know of the posterior Wernicke’s area important to language comprehension and of the anterior Broca’s area important to language production.  These are basic to conversation of course.

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The speech signal is an unbroken stream of sound produced by air blowing through the vocal folds and then modulated by the speech tract (pharynx, nasal cavities, tongue, teeth, lips) to mark phonemes (vowels and consonants).  The auditory system processes this signal and somehow recovers the linguistic units to find words, sentences, etc.  Our brains do this rapidly and all at once, which makes it possible to interrupt someone to say what we want rather than listen to them. More on manners later.  Here is a graph of the speech signal for a sentence that took 1.5 seconds to utter (must have been a slow drawl at that).

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No breaks are between words, the stress or accent on different syllables is indicated by the amplitude of the graph, and the phonemes are there somewhere.  That is not the whole story, however, because while the left side of the brain is encoding/decoding the syntactic units, the right side is doing the same for the paralinguistic aspects of the signal, the intonation patterns carrying the sentence modality (statement, question, exclamation, etc.), the emotional cues therein, even the basics of the speaker’s identity, sex, age, geographic origin, etc.  This is done all the while as the right side also monitors the non-verbal cues for the listener’s interest and attitude along with the rest of the immediate concrete situation.  Again the left side’s language may be about information immediately available in the current situation but more probably is about information displaced in time and space, real or unreal.

The term ‘voice’ is used in many ways, a speaker’s basic necessity, a singer’s instrument, a poet’s distinctive mode of expression, etc. Biologically voice is the special sound to which our brains are attuned; a good part of our brains is dedicated to receiving and producing this figure so distinctive from the ground of ambient noises.  And not just humans.  The latest issue of Science News reports a study in which dogs were trained to lie very, very still in an MRI while sounds were played.  The results indicated that dogs also pay special attention to voice though not to the same degree as humans, which only makes sense given how well they engage with us and us with them in a special sort of conversation in which they are the better listeners and speak with their eyes, tongue and tail.

Coming soon: conversation and music

cosmic quibble

The next episode of Cosmos will come in in a few hours and I wanted to post this before that.  Last week was another great one as Neil deGrasse Tyson challenged all of us to embrace a scientific view of life.  

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He acknowledged that some people worry about being related to monkeys and then asked wryly, “How do you feel about being related to an oak tree?”  I loved it and my Celtic forebears with their Druidic ways certainly approved.  But one quibble:  he said several times that the environment “shaped” or “molded” the forms of life and I think it is important (more than a quibble really) to understand the complexity of the relationship between an evolving organism and its environment.  Susanne Langer said the environment determines what is given, the organism what is taken.  An organism is the agent shaping its ecological niche.  The agency of evolution, DNA mutation, changes the animal to maybe exploit the environment more successfully, more probably to reduce the the organism’s internal viability or to hinder its adaptation to the environment.  The environment, however important a constraint it may be, is not an agent ( at least in my grammatical sense of things).  That said, be there or be square.

Mixed metaphors

Things are about to get complicated here as I mix some metaphors up. To begin I will post this optical illusion developed by Gestalt psychologists in the early 20th century.  They used it to illustrate that the brain’s visual perceptual system can operate with one gestalt at at time.

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You can focus on either the faces or the chalice but not both at the same time; one figure must be relegated to ground in service to the other. The gestalt theorists gave us a really good and useful concept there.  Simple enough.

Focus on the chalice for a moment.  Our biological roots have culminated in our symbolic capability.  Symbols carry meaning, so we must create meaning.  Symbols represent things even if those things are conceptual in nature; nothing like quarks or multiverses or Higgs fields or Zeus out there really.  For me the holy grail of neuroscience is to understand how our brains make meaning using symbols.  This may not be possible; it will certainly not be done easily.  Other goals, like understanding psychiatric disorders, are more important, but still, the pure science of the matter is that we seek to understand the basis of our humanity and this basis derives from our symbolization ability.  More later.

Focus on the faces for a moment.  Long years ago I became fascinated with conversations, the linguistics, the pragmatics, the paralinguistics of conversations.  Exceedingly commonplace with an endless variety of purposes and forms, conversations require that symbolic processing proceed rapidly, fluently, accurately about topics that are more often displaced in time and space and not immediately evident to our senses.  We converse by understanding another and expressing ourselves and the power and facility with which we do this is amazing.  Working as a speech/language pathologist I worked with children facing various challenges in conversing but they all wanted to converse just like they wanted to walk.  Conversing is in our nature and of course it is biological.  More to come.

So the optical illusion is a metaphor for the holy grail of neuroscience, symbolization, and for perhaps the most pervasive distinctively human behavior of all, conversation. One is ground for the other’s figure.  Stay tuned.

Culture change and holiday

In my readings of the past, especially of the Celtic peoples, a truism was that Christianity sought to preempt ancient holidays and places.  Notre Dame in Paris was built on the site of a Druidic holy place, All Saints Eve and Day took over Samhain, Easter on Beltane, Christmas on the winter solstice.  I think of such cultural change on St Patrick’s day even more since I asked a good Irishman why they drink to celebrate someone probably opposed to such revelry.  

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He answered that St Patrick came and replaced a priestly class that worked along side the people, adding to the community resources, who supported centuries of agricultural practices, cultural transmission, respect for women, maintained connection to the natural world, etc. with a priestly class that took resources to build huge churches and feed themselves who did little to help out, relegated women to property and breeding, colluded with the English in subjugating the citizens, enacted religious strictures in secular law, forbid and made criminal divorce and remarriage, made unmarried women give up their children in shame, and preserved for years the ability of priests to molest children and that maybe that was why the Irish drank on St. Paddy’s day.  Could be and no wonder they say change is hard.

Elephant voice recognition

I posted a few weeks back about elephants (Indian these were) comforting one another when in distress.

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Now a report comes about African elephants recognizing which humans are dangerous by their voice and the language they speak.  Researchers played audiotapes in the wild and observed the elephants’ reactions.  Briefly, the elephants sought to escape when they heard a Maasai male’s voice but not a child’s or female’s voice.  Maasai are hunters/herders and known to hurt elephants in competing for the land.  When they played male voices from another tribe speaking a different dialect, the elephants’ reactions showed less concern, more defensive and less escape.  The phrase was a neutral one, something like, “Oh look, here comes an elephant,” spoken in a calm voice.  The report was published in the Proceedings of the National Academy of Sciences.  Here is link to a story about it.

http://www.globalanimal.org/2014/03/13/elephants-are-all-ears-measure-danger-through-voice/

In humans voice recognition is also quite specialized and is lateralized to the right hemisphere.  We recognize individual identities or a stranger’s sex, race, age, emotional state, even intent solely by their voice.  Elephants do not have language (not to the extent that they can tell us about it) but their brains, like all mammalian brains, have some degree of lateralization.  I do not think we know much about this in elephants.  Is their voice recognition also right-sided?  Do they have something like handedness or is their trunk bilaterally controlled?  The identification by dialect implies rather specific feature detectors in their auditory processing system. Interesting but difficult to answer without using elephant EEG or fMRI so I guess and hope we let that mystery be for awhile.

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Good science needs imagination

We are very happy here that the much anticipated reincarnation of Carl Sagan’s Cosmos has arrived and that Neil DeGrasse Tyson, the writers, and crew look to have done a wonderful job.  One of the themes Dr Tyson touches upon several times in the first episode is the importance of imagination to the hard work of the empirical method.

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I recently finished Sean Allen’s book, Brave Genius, about Albert Camus and Jacques Monod. (Let me add to what I said below.  The book is excellent, well-written, well researched, and well worth anybody’s and everybody’s time).  Monod won the Nobel Prize in medicine along with two colleagues, Andre Lwoff and Francois Jacob.  During their work when Monod (and maybe Lwoff) were on vacation from the Paris summer, Jacob stayed behind, working in the lab and trying to figure out what if any role our genes had in governing the enzyme adaptations they were trying to understand.  

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He was very frustrated (and no doubt hot), gave up the day’s effort and went to a movie with his wife.  Shortly into the film he ‘imagined’ a solution and became so excited his wife suggested they leave the movie so he could work on it.  (Can’t you see that?)  When Monod returned from his holiday a few days later, he was very skeptical about Jacob’s idea but they explored it empirically in the lab and Jacob’s imaginative flash of insight led to the discovery of messenger RNA, the go-between by which DNA governs all cellular activity. Voila!

Also, remember the story of August Kekule, the chemist who discovered the ring structure of the benzene molecule around 1885.  He described  having a dream about an ouroboros, an ancient symbol of a snake grasping its own tail, and awakening to realize that the benzene molecule was a ring of 6 carbon atoms.  And don’t forget Einstein daydreaming on the trolley to and from his job at the patent office.  We’re talking about the scientific power of dreaming here.

                                                                              

Beringia

Beringia is the name of the land bridge between Asia and North America, now submerged but above water during the last ice age when much more water was held in glaciers.  A study in Science reported by Earthsky examined sediment cores from the submerged land to find it was once about 25,000 years ago covered by vegetation and experienced a relatively mild climate.  Here’s the link:

Did first Americans live thousands of years on Bering Land Bridge?

This finding, when considered with recent genetic analyses, suggests that the people who became our indigenous Native American population lived in Beringia in relative isolation for thousands of years before completing the migration into the Americas some 15,000 years ago.

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This 15,000 year figure is generally held by archeologists but still remains controversial with some evidence that they arrived earlier and even may have crossed via Iceland and Greenland from Europe.

Evidence of humans, Homo sapiens, is found in many places.  Curiously our ancestors often lived in colder climes and higher elevations.  Why?  Maybe good hunting for them, fewer predators for them to worry about.  Maybe.  We have been and continue to be a species of explorers.  This seeking the difficult new challenges our constitutions and our creativity so that even if there is not a material benefit, we grow hardier and smarter.

Each generation also grows hardier and smarter by challenging themselves to leave mother’s side and explore the surroundings before returning to mother for refueling.  This phase of separation and individuation is called practicing.  Schore documents how important it is for the brain that we develop such emotional autonomy and self-regulation.  The same is true, I think, over our evolution.  Next up, a one way trip to Mars?

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