Professor Bourdieu, meet Dr. Damasio

I am reading Descartes’ Error by neuroscientist Antonio Damasio, who always has something interesting to say.  I don’t know which one of Descartes’ errors he focused on yet; Damasio says early on he will reveal this at the end and I am only 2/3 the way through, so more later.  He does emphasize several important modern notions.  Our higher level cognitive abilities are grounded upon lower level processes.  One of these is our emotional capacity, which he says is critical to our thinking adequately about social interaction and thinking through and accomplishing tasks.  He describes several clinical cases illustrating the negative impact on cognition of brain damage affecting emotions, one of which is Phineas Gage, a famous instance from the 1900s.  Gage was tapping some explosive into a hole preliminary to blowing up some rock in the way of construction when the explosive went off prematurely and sent a steel rod through Gage’s head, destroying areas in his frontal lobes.

Gage survived and recovered much of his cognitive functioning, but while he could think and talk about many things, he could not do so much.  His efforts dissolved into blithering, meandering actions without any focus and movement towards completion.  Along with this his doctors noted that he had very flat affect; he just was not concerned about anything.  Damasio and his wife explored the records and even studied what precise areas were probably damaged, given the early descriptions of the injury, and they explored several contemporary cases where strokes, etc., had damaged patients’ brains similar to that hypothesized for Gage. Investigating these cases very systematically, using modern imaging techniques and neuropsychological tests, they demarcated a clear syndrome wherein almost all cognitive skills were left intact, yet the patients were virtually affect-less and unable to accomplish much due to their dithering.  Ah, says Damasio, emotion is necessary to cognition.  Indeed, while they are different, they are mutually interdependent for adequate adaptive functioning.  Amen!

In developing a hypothesis to understand how this could be, Damasio recognizes the important research of Amos Tversky and Daniel Kahneman, showing that our rational processes are far from logically fail-safe and quite dependent upon cognitive shortcuts that they call heuristics (see post 6/11/18).  Damasio finds a linkage between these heuristics, austere thinking and emotional buttressing.  He sees a neurological system with an important nexus in the ventral medial frontal lobe that creates dispositions for action he calls ‘somatic markers’.  His discussion here is quite complex with several perspectives and lines of evidence to support it.  I began to understand it when I realized its relevance to Bourdieu’s habitus, of which more later.

Damasio’s somatic markers come about through the interaction of cognitive processes rendering the situation, actions, and consequences and of emotional processes that render an assessment of the desirability of the action.  They are learned or acquired through experience and that experience is referenced to the body, i.e., the soma, thus the name somatic markers.  As we encounter (read ‘generate’ or ‘delineate’ mentally) situations, we respond based upon these dispositions sometimes and at other times we engage in a more rigorous cognitive evaluation.  This fits with Tversky and Kahneman’s thinking fast and slow—sometimes we use quick heuristics and sometimes we actually think things through. This also fits with Damasio’s observations of patients with frontal lobe damage like Phineas Gage—they know the situations and can even articulate the rationale for their actions, but they fail to change their dispositions and learn from negative consequences.

Damasio discusses current empirical support for his somatic marker hypothesis and what needs to be determined through future research.  One aspect here is that while we primarily process these markers through objectively happening situations, we also, and increasingly so with intellectual development, secondarily process situations “as-if”, i.e., we imagine virtual situations and develop hypothetical or abstract markers, so that our dispositional actions are “as-if”.  This is a necessary level if symbolic activity is to be accounted for in this hypothesis.  Damasio goes on to say that, given the learned nature of these dispositional markers, he expects a lot of individual variation in our acquisition of these proclivities.

Now as I worked to understand this, several things came to my mind.  First is Bourdieu’s exposition of the habitus, our cultural ways of doing things (see post 8/13/17).  Some of our “as-if” somatic markers would be acquired through the processes of acculturation, e.g., how to marry, how to organize group activities, the social mores governing group interactions, etc.  Some somatic markers, primary and secondary (as-if), would be acquired through the processes of socialization, e.g., how our family and culture express emotions, treat with elders, etc.  It seems to me that Damasio’s somatic marker hypothesis provides us with a way to begin understanding the neuropsychological underpinnings of the habitus.  Most excellent!

Return to the idea “of individual variation in our acquisition of” these somatic markers and their associated dispositional actions. Here individual variation can mean the variation between people inherent in their socialization, acculturation, and acquired invariant dispositions (after all we each experience our life quite differently from anyone else, so how could our dispositions not vary?), and variation within each person according to the processing systems of our specialized neurological structures.  This latter is the one I find especially interesting, because we can see an important distinction in the acquisition of somatic markers and their dispositions. Damasio refers to it as the distinction between social interactions and the actions needed for praxic solutions, i.e., how to do things, not do with people.  I translate this to convey that we have social dispositions both personal, e.g., differing displays of affect according to audience, and not-personal, e.g., driving a car.  This seems to me two basic modes of processing context and intent that are inherent in our brains.  I think it is not just personal-impersonal—it is also immediate, because most social interaction is most appropriately immediate and so biased to the right hemisphere, or displaced because we deal with so much information that is not immediate by using our language to create context (topic) and figure (intentional propositions) and so biased to left hemisphere processing.

Is the experience being learned from as we form a somatic marker part of our autonoetic or autobiographical/episodic record, which is heavily biased towards interpersonal activity and so emotionally engaged and infused, or experience dominated by abstract and semantic memories, which are heavily biased towards accomplishing intentions and so emotional control and dissociation are paramount?  Damasio discusses the VMPFC, the ventral medial prefrontal cortext, as a nexus for composing somatic markers.  What else goes on there?  Damasio says this region is special for its connections to virtually all the rest of the brain, saying there is no experience to which it does not have access.

Cortical_midline_structures

DMPFC=dorsomedial prefrontal cortex MPC=medial parietal cortex Illustration provided by Georg Northoff – Georg Northoff Brain and self – a neurophilosophical account Child and Adolescent Psychiatry and Mental Health 2013, 7:28.

The prefrontal cortex is important to human cognition because it links with so many other areas and because it processes this information in some specific ways.  Damasio says the lateral or outside side processes information from the outside, e.g., objects, consequences of actions, etc., and thus can be dissociated from more personal engagement.  This stems from its connections with posterior areas that provide information about perceptions and body orientation and with motor planning and enactment areas, plus areas giving rise to plans and intentions in general.  The inside or medial prefrontal cortex, those areas hidden down in the cerebral commissure, function quite differently, as I have posted in recent weeks.  Damasio notes that they work with bioregulation and social interaction, i.e., they maintain emotional control and govern relationships.  Hmm, core (inside) areas work with somatic and personal engagement and lateral (side) areas work with actions with non-social environment. For a complex example using both, consider your ancestor who cooperates with his clan, with one of whom he just had an argument, while hunting a larger animal and moving silently through terrain and coordinating the use of his weapons.  It takes a whole brain to make a functional mind.

Recall now two recent posts, one on autonoesis (9/16/18: Existential neuroscienceand autonoesis) and one on Decety’s model of empathy (9/9/18: Whose brain could we study?).  Autonoesis refers to experiences that are important to the self, i.e., the self is engaged emotionally and socially as opposed to those humdrum activities that bear little import for the self, e.g., adding numbers, driving, washing dishes (unless doing so mindfully).  Marco Iacoboni thinks that our mirror system plays an important role here; specifically the medial parietal cortex (posterior and part of Empathy Central) and the dorsomedial prefrontal cortex (frontal area important for motor and intentional activity) light up together when the experience is deemed important. He cites research showing that these areas light up when political aficionados discuss politics and do not light up when someone is bored by that topic.

Jean Decety’s model of empathy emphasizes that our brains distinguish our autonoetic experiences from those we empathically feel from another person, that we are able to set our own autonoesis in the background in order to fully consider the other person’s perspective, and that we can regulate our emotions in order to maintain our focus and keep diverse information in mind regardless of the social context.  These same prefrontal areas contribute to these empathic functions, including processing social feedback from others about ourselves (and that shades into autonoesis very quickly).

The formation of Damasio’s somatic markers and behavioral dispositions involve both autonoesis and empathy. We acquire (or not—consider our president per 9/9/18 post) our cultural ways of forming autonoetic experiences and of empathizing with others as we are socialized and acculturated.  These developmental steps are at the root of Boudrieu’s habitus.  We can see this in how different cultures manage such phenomena.  Autonoesis is different between Asian and Western cultures. Asians see the self as defined by and subordinate to social relations; showing off is extremely poor manners. Westerners see the self as defined by individual achievement, so showing off is only ‘natural’.  Similarly empathic expression differs with Asian cultures maintaining a more stoic expression around non-intimate others.

A more deleterious example of differential empathy development comes with our acquisition of racial or other constructs, e.g., our habitus holds some other people distinguised by their skin tone, religions, or other markers to be inferior, even the enemy not worthy of humane consideration.  These cultural features can be changed in an individual when we understand that commonly held assumptions are wrong, e.g., rejecting our family prejudices against another race, and they can shift over time, as when our art shows us a deeper truth, e.g., Brokeback Mountain,Call Me By Your Name,Guess Who’s Coming for Dinner, or South Pacific (see my post 3/6/18: art and cultural shifts).

I want to post again about Damasio’s book, which I find to be informative, provocative and leading to a wisdom of sorts.  And I want to connect these ideas to my conceptualization of the soma, its brain, and the MEMBRAIN.  So, hasta la vista and travel on.

 

Whose brain could we study?

I am going out on a lark here.  I just read an excellent review of research along with a proposed model of how our brains do empathy:  “A social cognitive neuroscience model of human empathy” by Jean Decety in another great collection of papers, Social Neuroscience: integrating Biological and Psychological Explanations of Social Behavior.  We are going to go into some complexities here but in truth, the reality is even more mind-boggling.  So Dr. Decety postulates 4 components to empathy:

  • ‘Shared neural representations’ which I understand to be the mirrored actions, especially emotional expressions, by which we resonate with one another.  (See posts 9/27/15, 7/29/15 & 7/31/15).
  • ‘Self-awareness’ which I take to be essential in knowing which resonant activity originated within us and which within the other.
  • ‘mental flexibiity’ by which Decety means the ability to set mentally one’s own perspective in the background and so enable the taking of another’s perspective.
  • ‘Emotional regulation’ which I understand to be quite basic to developing empathy and also higher intellectual skills. The development of emotional regulation is critical to our maintaining focus on our current mental set, intention, and task as well as to setting our personal feelings aside to address the concerns of others.

As Decety explains these 4 components, he reviews the neuroscience, including clinical findings, relevant to each.  For example, autistic people can generally engage in mimicry, i.e., mirroring, intentionally, but do not do so incidentally and this latter is necessary for mentalizing about another’s state of mind. It is one reason researchers like Ramachandran and Baron-Cohen (see my post 7/29/18 ) think autists suffer from a mirroring deficit.

The neuroanatomy supporting empathy is also profoundly complex.  Generally there are centers in the posterior brain, especially in the right hemisphere, that receive and integrate social information, and centers in the front of the brain that provide executive functions and guided responses to that information, again especially on the right side.  The front and back areas communicate with each other directly in some cases through long fasciculi, i.e., nerve fibers traversing the cortex, and also through their interconnections with lower centers like the hippocampus for memory and limbic system for emotional processing.

Lobes_of_the_brain

Exterior view of left hemisphere. Lobes are same on the right. Some structures are deeper within the larger folds.

Decety does an admirable job sorting through various findings to present relevant hypotheses about neural functioning.  For example,

  • The frontal polar cortex facilitates inhibiting our own perspective, which is the default one that we usually follow in our considerations, in order to take on another’s perspective. This area also helps evaluate our own responses and behaviors for their contextual fitness, i.e., do they fulfill the intent? Was the intent properly developed from a coherent adequately formulated context?
  • The prefrontal cortex interacting with the inferior parietal lobe (in the back and integrating information from many perceptual sources) and the insula (old cortex deep with the brain kind of in the middle) on the right side helps to differentiate actions from one’s own self from those of another.
  • The paracingulate sulcus (again old cortical structures deep in the brain) in the medial prefrontal cortex helps process social feedback, i.e., how do others view our actions?

And so forth.  I always find it amazing to consider that while these areas are performing these particular functions, they are also contributing to many others, e.g., attention and focus, memory input and output, etc.

Two ideas here struck me as particularly interesting.  First, damage from say a stroke to the right frontal lobe so important to emotional expression and social responding sometimes shows up in personal confabulation, i.e., the patient makes up stories about themselves seemingly unaware that he is doing so.  The second is that when faced with the personal distress of others, say due to their own circumstances or even to their assessment feedback of the original actor’s actions in some matter, our brains can respond either with empathic concern given their perspective (an optimal response) or with egoistic anxiety (retreating to one’s own narcissistic concerns).

Well, we have covered a good deal of ground here.  In my past life as a clinical psychologist I worked with many youth, including some with attachment and sexual aggression problems, who had deficits in some of these empathy ‘components’.  Each person’s deficits were unique in form and history and most retained some islands of empathic functioning.   Let me list some major areas:

  • Failure to resonate with another. The person may only resonate when the other mirrors them, but they seem unable to mirror or resonate with the other’s feelings.
  • Confusion as to the agent of thoughts and feelings. They think their own thoughts and feelings are also the other’s and they may fail to process accurately social feedback when the other tries to disagree or otherwise present their own perspective.
  • This leads to problems with perspective taking. They may assume that their perspective is shared by everyone.
  • Poorly developed emotional regulation presents difficulties for staying on mental task and intent as well as for responding with empathic concern for the other—instead they act upon their own egoistic anxiety and fail to engage socially in an adequate manner.

As I read and thought about these ideas I kept thinking of someone who seems to experience all of these deficits despite what otherwise may be intact intellectual capacity.  And I wondered if scientists could study that person’s neurological structure and functioning to learn from what seems to be an unusual case, someone whose empathy deficits appear global but without a history of neurological disease or injury or of developmental trauma.  I can think of only one person like this at the moment and that is why I want to ask our President, Mr. Trump, to donate his brain to science upon his death.  I know more could be discovered if he were to undergo evaluation while alive through experimental protocols, e.g., using fMRI, but I also know he is much too busy being president and running his businesses to do such a thing.  I am not talking about a simple post mortem autopsy such as the one that found a tumor impacting the amygdala of Charles Whitman, the Texas tower shooter (see my posts 9/3/15 & 12/26/17), but a detailed scientific examination of his brain structure, sort of like we wish would have happened with Einstein’s brain, which unfortunately was not done very rigorously.  I believe a knowledgeable neuroanatomist could assess the integrity of most of the relevant areas and some of their interconnections.

Now I have no way really of getting my message to our President and I am not on Twitter nor knowledgeable about it, but I wonder if some tweeting aficionados sent out some messages using #SaveTrump’sbrainforscience (if I understand the format correctly), what might transpire.  Travel on.

When 1 +1 = 3

Actually I am just playing around here; I do not think the above equation is ever correct, but I am exercising my brain by pretending so. Though, now that I think more about it, sometimes we do take one idea and combine it with another and so develop a third that is greater than the sum of its parts.  Let’s try it and see.

Georg Streidter in his text Principles of Brain Evolutionwrites that, though the idea is too general to offer much guidance for research, it is true the larger the brain, the more capable the species is in adapting to other niches, and that the larger the brain, the more the species engages in play. General yes, but also intriguing. Playful behavior speaks to a flexibility of behavior and indicates that the animal has greater degrees of freedom in developing actions that exploit opportunities and ameliorate exigencies, and that helps in adapting to the changing contingencies of the world. Plus, Jaak Panksepp in his book, Affective Neuroscience: The foundations of human and animal emotions, writes that rough and tumble play, e.g., mixing it up with conspecifics in various ways, promotes joyful feeling.

So we have the ideas that a larger brain relative to body size increases behavioral degrees of freedom, enables greater adaptation in the face of environmental challenges, and leads to greater play and that helps to generate joyful interactions with conspecifics.  Now consider my idea about our lateralization, i.e., that the right hemisphere generally focuses on the current situation, especially the activity in the social domain, and the left hemisphere generally focuses on information displaced in time and space, especially information controlled through linguistic symbols.  One observation neuroscientists have made is that, again generally, the emotional valence of right sided processes is somber, maybe sad but at least seriously practical, while the emotional valence of left sided processes seems lighter, even happy.  I think this might be because right sided considerations concern the current activity where the situation is delimited and possible actions are proscribed, i.e., behavioral degrees of freedom are fewer because of the practicalities involved. Left sided considerations, concerned with some abstracted and symbolically constructed situation, involves many more degrees of freedom because the situation is fluid and possible actions open to creative solutions.

Going a bit further, this difference seems to reflect the distinction between serious, practical engagement, e.g., work, and light-hearted speculative engagement, e.g., play.  Now consider the famous masks of drama, tragedy and comedy, and how the plays end.

theatre-masks-happytheater-masks-silhouette---free-clip-art-19tqgcvz

A tragedy usually involves a final action with little possibility for further development; the play ends with virtually no behavioral degrees of freedom for the characters.  A comedy is the opposite; the characters leave the field of play, i.e., stage, to live happily ever after—the future is wide open with many degrees of behavioral freedom.  Classical dramas followed this convention fairly closely.  When we approach modern times, drama begins to reflect the curious muddle of our lives today.  Just how does Waiting for Godot end for these characters of limited repertoire?

One more idea seems relevant here, at least to me.  I am reading The Embodied Mind: Cognitive science and human experienceby Francisco Varela, Evan Thonpson, and Eleanor Rosch, a fascinating book in which they seek to bridge the quite recent positivistic efforts of cognitive scientists and the understanding of human subjective experience as understood by long-standing Buddhist traditions (a slow, deep read for many reasons).  Deep into their analysis they assert that analysis of the visual and other neural systems shows that the bottom up flow of information, e.g., from the retina through the lateral geniculate nuclei to the visual cortex, which we think is decisive in determining our perceptions is actually exceeded by the top down flow of information from higher neural centers.  These processes from above contribute to determining perceptual forms, figure-ground, attention and focus, and more we have yet to understand.

Let me imagine just a bit further that the bigger the brain, the more top down processing flow there is (because that is where the enlargement is) and that is what helps to develop greater degrees of freedom, increase adaptive flexibility and empower playful action.  Now consider the idea I have promoted here about how to define sentience and consciousness.  The general orthodox definitions show that the terms are conflated, i.e., used as synonyms, but for a variety of reasons I have given before (e.g. see post on 4/21/16, or 11/30/17), I think they are better distinguished as follows.  Sentience grows as the basic function of an organism in apprehending its ambient; this is based upon perceptual organs and is what Susanne Langer called impactive activity, i.e., neural action engendered by energies and material impacting on the soma from without.  Neurologically this is what Varela and colleagues call the bottom up processes.  In my heterodoxical view consciousness is autogenic (Langer’s word for the autonomous and independent activity of the brain); it is the top down processes cited by Verala et. al.  Consciousness is what we bring to sentient processing that is not engendered by the current perceptual processes but by our own shaping of our sentient domain and even more for humans by the displaced information remembered, imagined, and controlled through symbolic processes.

So our bigger brains have allowed us to bring more to the current social situation, what I have characterized as heightened empathy leading to deeper intimacy, and more to our interaction with the world at large through our symbolic control of information that we apply to our experiences of the world around us and ourselves.  Take a couple of ideas, add them together, and get something more, eh?  Time to travel on, playfully.

Evolutionary tidbits

To reiterate my understanding of the biological roots of our humanity, I see human empathy as something special and it laid the foundation for symbolization and that enables us to think and talk about everything and nothing and to create it if it is not already there in reality.  Through our empathy we humans are keenly aware of another’s mind, that they have subjective considerations, and how we can interact with each other mindfully.  Symbols carry this social effort forward with scope and power.

This empathic capability is centered in the right hemisphere that processes kinesic communication and maintains Empathy Central in the temporal-parietal junction where knowledge about our relationships contributes to what the academics call ToM (theory of mind).  Anyway, my thought is that this keen sensitivity to others’ minds became integrated with our mirroring capabilities, so that certain actions could be replicated readily upon observing them in another.  This replication of mirrored actions comprises the invariant forms of social communication, and when our mirroring system came to include vocal signals, so that we could hear a conspecific vocalize/verbalize and reproduce that sound and not just the objectively observable motoric behaviors, e.g., lifting a cup to drink.  This is the functional significance of the arcuate fasciculus on both the right and left sides, but especially on the left, where the af enables the repetition of what we just heard another say (see my post of 4/24/2014 on the arcuate fasciculus and mirroring).  Putting together, i.e., integrating, the awareness of another’s mind and the knowledge produced by the mirrored invariant behaviors led to symbolization, at first linguistic and then artistic (ask me to explain that sometime).  Symbols, if you remember, have a deep structure (what resides in our minds subjectively) and a surface structure (what we use to formulate and then communicate those subjective musings), and voila! language, art and the cultural wealth of our kind.

That said, I have been reading Georg Striedter’s Principles of Brain Evolutionand find a couple of evolutionary tidbits that help to carry my speculative imaginings forward (and I find nothing so far contrary to this path). Consider that human eyes are almond shaped and that our irises are surrounded by white sclera while the eyes of other primates are round and the irises surrounded by dark sclera (though the sclera hidden within the eye socket is white.  Striedter interprets this to show that we humans monitor each other’s gaze and so gather more information about the other’s subjective musings; further that our eyes’ structure facilitates this with its almond shape and white sclera shows that such kinesic communication is important evolutionarily. I see this as an example of our keen awareness of the other’s mind.

Think of some examples of this.  Parents follow the gaze of pre-verbal infants and move to facilitate their exploratory activity.  As Michael Tomasello explains, joint action is a critical advance in our social coordination and eye gaze is an important means by which we cooperate, e.g., one holds something still while another performs a more intricate action such as a nurse clamping a wound while another stitches it up, or one hunter with a bow shifting gaze to match another’s and finding prey.  Finally in this regard, in my early career I learned about the challenge of hearing impaired children (and adults) who must watch the other’s hands to communicate about a task that needs to be seen to be learned. Eye gaze is important in juggling these gaze shifts and we humans have extra talent for this.

Father child

joint gaze and joint action

Streidter also discusses the size of our brains in absolute terms, compared to our body mass, relative to other animals, the amount of cortex relative to the medulla, etc.  He points out that large brains are ‘expensive’, e.g., they require high protein diets, they pose problems for live births due to mismatch between skull size and birth canal, and they pose challenges to communication between neural areas.  This last comes about because areas farther away take longer to communicate with each other and that poses a problem for timing.  Much of our neural processing depends upon the simultaneity or temporal match of parallel processes.  Our brains have evolved with some work-arounds such as long, thicker nerve tracts that nerve impulses travel along faster than thin fibers.  Our brains have many more modules and these connect especially to those nearby with some longer fasciculi, e.g., the arcuate fasciculus, the superior longitudinal fasciculus, the claustrum and the corpus callosum, bearing the burden of longer range communication.

Sobo_1909_670_-_Uncinate_fasciculus

The arcuate fasciculus is part of the superior longitudinal fasciculus. Thicker axons help nerve impulses travel long distances faster.

Now here is another interesting tidbit.  Our corpus callosum is relatively smaller than those in other primate species, i.e., our cerebral hemispheres are less connected than might be expected.  Streidter says the data show that the human brain is more asymmetrical than other species’ brains; this works because our two hemispheres specialize in different functions (yes, even as they perform much of the same functions, one leads, and while brain damage when young can be compensated for, damage when older is less so because the specialization has become at least partially irreversible). Again this difference in connectivity is relative; I have posted here before that studies of our connectomes show females generally have more bilateral connections, i.e., they make more use of their corpus callosum, while males have more connections within each hemisphere than between.

corpuscallosum

corpus callosum with part of right hemisphere cut away

Now this bit of information speaks to two issues.  First is that females and males (please remember that I use the terms in a relative manner and appreciate all manner of androgeny in our variations) approach interactions differently.  This is especially noticeable in preschoolers where girls are both more verbal and tuned into relationships and boys are somewhat less verbal and their attunement to others is, shall we say, less robust.  Actually, talking with my 30 something daughter and others, this difference may even be accentuated in mature humans (maturity, again, is a relative term, guys).  In any event, the functioning of the connectome when emphasizing social and linguistic information together would use the corpus callosum more fully and that would correlate with a female sort of pattern.

The second issue here goes back to my thesis that symbolization arose from, first, the integration between the keen empathic apprehension of another’s subjectivity and the invariant behavioral forms that operate in mirroring, and then, second, once the connections are formed, their separation into the surface and deep structures of our symbols.  Human brains are more asymmetrical and this I associate with the differentiation of function between Empathy Central on the right side and linguistic functions on the left, e.g., one side is pragmatic and the other syntactic/semantic.

The last tidbit comes from Streidter’s analysis of the human brain’s enlarged lateral prefrontal cortex (adjacent to motor and premotor areas) primarily on the left side.  This relatively species-specific area serves, Streidter hypothesizes, our abilities to use our hands and words in very flexible, facile, novel and unconventional ways.  We are able to do things hitherto unseen, un-imitated and even unimagined until we do them.  This includes our words as well as our hands.  This highlights one of the great paradoxical strengths of our language. We use words, conventional symbols with socially established meanings, to say many things that have never been said before, i.e., they are novel and unconventional.  We do this day in and day out in small and large ways for mundane and profound topics.  Back in the day Noam Chomsky focused on this generative capacity to demonstrate the theoretical poverty of behaviorism, and we are still learning about this today.

Lobes_of_the_brain

lateral prefrontal is in lower blue area towards the front

So a long post.  Funny how tidbits expand when I am (you are too hopefully) having fun and learning about our humanity, eh?  Travel on.

Partial review: The Encultured Brain

Sometimes quantitative assessments lead to important ideas.  I have been enjoying later chapters in my new book, The Encultured Brain: an introduction to neuroanthropology, edited by Daniel Lende and Greg Downey.  Their early chapters giving synopses of later chapters to introduce the rest of the book seemed more a marketing ploy for yet another new academic discipline (worthy, yes, but do we really need a new term for every time we do cross discipline thinking?)  Their chapter on “Evolution and the Brain” was, however, magnificent, and later chapters by others have so far been very interesting.  So consider this list of findings from their brain evolution chapter.

  • The biomass of humans is 8 times that of all the wild terrestrial vertebrates, i.e., we are successful replicants. (Also I remember von Neumann’s estimate that each human body has about a tablespoonful of genetic material in all its cells that control the soma).
  • The genus Homo appeared around 2,000,000 years ago with a sudden increase in brain volume that then slowly increased until 500,000 years ago when another surge in brain size appeared.
  • Human encephalization (the concentration of nervous tissue in a brain, i.e., head) is 5-7 times what would be predicted based on a mammal of our size.
  • As the neocortex evolved to dominate lower brain structures, specialized cortical fields developed that facilitated complex processing and inter-connectedness throughout the brain. Early mammals have 15-20 cortical fields; humans have maybe 150.
  • Larger areas both evolved later and mature more slowly.
  • Our brains have continued a mammalian and primate trend in lateralizing so much that some scientist refers to us as the “lop-sided ape”. (In addition, remember that males and females have relatively different patterns in our connectome with males showing more connections within hemispheres and females more connections between hemispheres).
  • Birds, fish and reptile brains grow throughout their life spans (neurogenesis or generating new neurons) but mammalian brains finish up neurogenesis relatively early.
  • Our brains triple in volume after birth while other primate brains only double.
  • Finally our post partum brain growth comes despite pervasive neural pruning in the first years of life; the estimates are that the adult brain has only 20-80% (quite a range, I know, but you get the idea) the number of neurons present at the peak early in life. Neurons survive because they become integrated into functional circuits; if they stay isolated, they die off.

 

All of these are pretty amazing and all support the idea that our brains are shaped, as Gerald Edelman maintained, first by genetic information and then in very large and important ways by experience.

White_Matter_Connections_Obtained_with_MRI_Tractography

Our connectome with many systems lit

Now Lende and Downey quote two well known neuroscientists (Cosmides and Tooby) that “our modern skulls house a Stone Age mind,” and I have no qualms about that because I think a Stone Age mind was actually a pretty good one (some politicians today cannot manage even that level of intelligence).  They also point to the remarkable and wonderful development of our social capabilities and find that we are drawn to social interaction for “intrinsic emotional rewards” and not just self-interest for our genes’ continuation.  And they recognize that the true power of human intellect, while derived from our rather different brains, is really due to the “synergy of many brains.”

Neuroanthropologists, as best I can see with my limited exposure, treat culture as part of our extended phenotype, i.e., culture is not an acquired overlay but is rather an integral component of the human Umvelt.  It is a direct outgrowth of our biological roots of empathy and symbolization (though I do not see anything here about art).  More to say later but I need to get to my farm work. Oh, one more recommendation for this book—the lists of references yield a lot of gems.  Travel on.

Neuroanatomy again

Generally I try to do 2 posts a week but I also farm for two markets a week and my time and energy is limited during this part of the year.  I saw interesting news this week on several fronts and will talk about agenesis of the corpus callosum today (and genetic studies of hunter/gathers vs agriculturalists and meditative brains later).  Earthsky.org reported a study showing that  people with callosal agenesis actually have other rather disorganized fibers connecting each hemisphere.

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Some few people are born without a corpus callosum.  Evidently the fibers develop in the fetus longitudinally in their respective hemispheres and do not cross over, yet these people have few, if any, mental sequelae.  Recent anatomical studies show that in these patients some fibers do cross over, not in any massive or organized manner, but sufficient to facilitate inter-hemispheric integration.  One of the truisms that I do not think gets much mention is that peoples’ anatomies vary across individuals a good deal and yet we all function about the same.  I have a colleague with congenital prosopagnosia, the inability to recognize faces; she can sit next to an acquaintance or ride with a familiar in an elevator without recognizing them unless they speak and she can recognize their voice. Some suffer from this due to stroke but she was born this way and does quite fine, even if she does have to apologize or explain sometimes why she seemingly ignored someone’s presence.  Anyway, we all have variations in our brains, organs, skeleton, and musculature etc not listed in the anatomy books.

Back to the corpus callosum.  Back in the 1960s, Roger Sperry and Michael Gazzaniga studied patients who had had their corpus callosums cut in order to control otherwise intractable epilepsy.  These patients generally show very little consequent dysfunction but with careful experimental procedures, they found that the two hemispheres carry on independent functions unknown to the other, i.e., they each seem to have their own consciousness.  I will not go into detail as so many are familiar with them but these are very interesting studies, so well done, and illustrative of good science and medicine running together.

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Now I decided to re-read Julian Jaynes’ book from way back then, The Origin of Consciousness in the Breakdown of the Bicameral Mind, for a variety of reasons.  I am finding I still disagree with him a good deal (and will address this in a future post) but he summons a great deal of scholarly information and scientific data that is interesting and informative.  He gives an excellent summary of the split brain research as he seeks support for his idea that the two hemispheres function very differently from each other.  He focuses on the findings that both hemispheres understand speech while only the left one produces speech, and goes from there with various stops along the way to say the right hemisphere spoke internally and that these were the voices of the gods helping ancient humans figure things out and solve problems of action.  Is this a biological root of religious beliefs?  Jaynes thinks further that until this neurological organization broke down, humans were not truly conscious.  Ah, well. More later but here is another view of hemispheric lateralization, left and right.

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