Dogs, language and laterality

The linguistic lateralization of our dog buddies spotlights a theoretical mystery

Many news outfits have published stories about a recent study wherein dogs were trained to lie still enough in an fMRI while listening to humans talk to them. The results indicated that our evolutionary partners processed emotional tones on the right side of their brains and specific words on the left, just like humans. The more we study dogs, the more we find how smart they are and how much we have adapted to each other for interaction. Check out the research done by Brian Hare and colleagues.

I first read about the fMRI study in Science News from 10/1/16. It provides a good summary (as they usually do—what a good magazine) and then they ended the article with the idea that because dog-human relations have only developed over the last 30,000 years, too short a time for evolutionary progress to produce such linguistic abilities, “some older underlying neural mechanism for processing meaningful sounds is present in other animals”.

This highlights for me the theoretical mystery on the biological nature not just of language but of symbolization in general (so it includes art as well). As I have said before, understanding symbolization is the holy grail of understanding ourselves biologically, and so let me render a conceptual outline of this mystery. First consider the bond between dogs and humans and that emotional communication through voice (and sight) is processed by the right side of the brain in both of us. We have researched this broadly in humans as intonation or non-verbal vocal communication, and/or kinesics. All of this to my mind is empathic communication and its processing is right sided; we find a cortical area for its integration there at the tempo-parietal junction that I call Empathy Central but the academics call ToM (Theory of Mind). Do dogs have an Empathy Central area? Unknown for now but I am taking bets they do and planning on how to spend my winnings.

zackyawn

Looking left, currently bored

Next consider this basic feature of lateralization. The right side processes emotional expression and empathic communication just like it processes the current perceptual-motor domains, i.e., the right side processes the specious present. The left side then directs its energies towards information displaced in time and space, initially as a supplement to the specious present by recognizing and recalling information and then increasingly as a virtual domain for information to be composed independently from current objective events. Language, as a symbolic function, is so powerful because it allows us not only to control the input and retrieval of displaced information from memory, not only because it allows the composition of new information from imaginal processes, but also and especially because it allows us to communicate about what isn’t there in front of us but exists only in our minds, apprehensible only to oneself and in symbolic communication.

So when the article ends by asking what the underlying neural mechanism might be, my answer is not about language but about its precursor in the symbolic control of displaced information. Why should that be lateralized to the left? Ah, because timing is important. The right side matures at a faster pace than the left, due primarily to the differential effect of testosterone which slows the left’s maturation more than the right’s (and so males show more distinct patterns of lateralization and more language problems from sometimes too slow a pace on the left side). The right side develops the capabilities to process current information early on while the left side is coming online, so to speak, a bit later, and when it does come on line, it is not totally in sync with the right sided processes for the specious present. Its information is displaced (read out of sync) almost from the beginning of the incipient specious present. Symbolic processes enable finer, more powerful control of such displaced information. So the right side focuses more on the current coin of interaction, i.e., empathic communication, and the left side more on non-current, i.e., displaced, information. Verbally this relies on lexical knowledge, the processing nexus of which is in the left temporal-parietal junction. As we learn more about animals, especially mammals, we will find the precursors of these underlying neural mechanisms in virtually all of them. You can count on it.

A couple more quick notes. It would seem likely that dogs were domesticated and became our close buddies because the genetic streams feeding their evolution ran close to ours—our brains are sympatico in how they process social information.   Human genetic streams, however, also evolved a lower larynx and hyoid bone, greater breath control, and oral-facial musculature thereby enabling articulate speech and even more critically to our humanity, gave rise to longer cortical fasciculi. The arcuate fasciculus is a prime example here. Remember that it carries the surface structure of words on the left side between front and back so that we can repeat what we just heard said. On the right side it might could carry emotional expressions for mimicking. (See my most popular post from 4/24/14, Arcuate fascicles, mirror neurons, and memes). The important feature here, however, is that these long fasciculi facilitate the composition of invariant information forms, e.g., words, discrete emotional forms, and their expression. (And how about art and its special modes of symbolization? Ah, beautiful). The creation of these invariant forms is what enables the separation of deep and surface structures and the subsequent development of syntactic control of their compositional connection. The creation of these invariant forms, both long-standing (lexical items) and in passing (conversation), by the welter of connectome activity in the presence of ambient flux is the remarkable basis for humanity’s intelligence and it has grown from deep roots.

Finally, remember to mark your calendars for Mammalian Heritage Day on November 2 and celebrate those roots. Travel on.

3 news stories

First, the Nobel committee awarded its prize for medicine to John O’Keefe, May-Britt and Edvard Moser (the latter two are married, an unusual occurrence in the awards) for their work on the hippocampus and entorhinal cortex showing that these structures map the animal’s environment and then maintain the memory to act as a GPS in the brain.  O’Keefe’s initial work was in the early 1970s; he and the Moser’s have extended it over the years.  Evidently O’Keefe has also demonstrated that this processing is temporally encoded relative to theta rhythms (see another post awhile back).  With this award the Nobel committee acknowledges the beginning of a marvelous path of research and knowledge  and recognizes that this basic science now contributes to the understanding of Alzheimer’s.  Well done everyone.

I have posted about the hippocampus several times before.  Here it is in the lower middle of the cerebral hemispheres, sidled up to the medial left temporal lobe.

Gray739-emphasizing-hippocampus

In rats the hippocampus keeps track of the animal’s location and recognizes old places and presumably encodes new ones.  Then the hippocampus communicates back and forth with the entorhinal cortex of the temporal lobe which processes where the animal is, where it is going or even intends to go.  Lovely.  Here it is as the yellow areas, 28 and 34.

Gray-Brodman-Entorhinal_Cortex_EC_

Now the glory of this comes in the temporal handling of information, maintaining data for the recognition of the old and familiar and for the recall of old to guide new activity.  While for rats this means spatial awareness (ah, maze running) and finding food and returning to the nest, for other animals the situation being processed comprises more complex elements until you get to humans and it supports our autobiographical experiencing among other things.  Way cool.

The second news item is that a study showed that people who had lost their sense of smell were significantly more likely to die within the next five years, a correlation and not causation, as we are wont to say, but I had a curious association here.  In my youth the orthodox view was that we were born with all the neurons we would ever have, and then later, they discovered that animals have new neurons develop all along the life span and the first place this was found was in the olfactory bulb (and yes, it does communicate both ways with the hippocampus) at the bottom of the brain.  Here it is.

1543,Vesalius'OlfactoryBulbs

Hard to believe it helps us detect over a million different scents and recognize some of them (ah, the hippocampal functioning again).  If someone has lost their sense of smell, the neurons here must have stopped regenerating; maybe that is a sign of a deeper lessening of the regeneration needed to sustain our life.  Just wondering.

The last news story is from a 60 Minutes piece this past Sunday.  I only caught the last few minutes.  It was interesting and I have some quibbles about the translation into popular lingo.  Researchers (especially Brian Hare at Duke) have found out that dogs do a lot more thinking than some give them credit for.  They know to go where the human points to find the goody, a task that apes are not good at.  Dr. Hare has developed intelligence tests for dogs that you can try at Dognition.  Most interesting is that he has done functional MRIs with dogs.  To do this they have to remain very still within the MRI machine and that in itself is some kind of good training.  The bit I saw showed that when a Q-tip with a human scent is  presented, the dog’s olfactory bulb lights up with activity.  If that scent is the owner’s, the caudate nucleus lights up as well, and Dr. Hare construes this as a reflection of the warm feeling the dog has for its owner because the caudate is one of the brain’s pleasure centers.  Lovely research really but here is the caudate and then my quibble.

Caudate_Nucleus_Structural_MRI

I guess Hare refers to the caudate nucleus as a pleasure center because the dopaminergic system runs strongly there and dopamine is integral to rewards, but the caudate is part of the basal ganglia which plays a large role in voluntary movement with lesser known roles in cognitive and emotional activities, even, some say, the response to beauty and affection.  So yes, that is or can be pleasurable but to discuss pleasure as a simple unitary concept is over-simplifying, and yes, I know he needs to be brief for TV but really.  This clouds other issues and complexities.  Perhaps smelling the owner engenders an orienting response and the basal ganglia would be involved in that.  Perhaps, as another researcher pointed out, when dogs and owners interact, both produce oxytocin, an affection engendering hormone, and the basal ganglia could be involved in that.  One thing I found amazing is that the dogs were able to inhibit movement despite clear activation of the motor system.  Finally, part of Dr. Hare’s discussion with Anderson Cooper was  about the possibility that the dog’s display of affection was only instrumental to get food, that as Mr. Cooper put it, his dog was only conning him.  Now that is a whole other topic with another Dr. Hare, Robert Hare, author of the Psychopathy Checklist, and I see no reason to go there in our understanding of man’s best friend.

So there it is, 3 semi-related news reports from later Sunday, a good day really.