Beyond hippocampus redux

Another article in Science News (4/30/16) shows our further understanding of this remarkable structure and lets me speculate even more. This new report is about research that shows that the hippocampus maps social objects, i.e., conspecifics or people if you are Homo sapiens as in the experimental study, or maybe rats if you are a rat, a mammal in which the hippocampus evolved early to serve memory especially for spaces and sounds in their case. This brings up two issues: one is how we conceptualize and talk about such phenomena and our research into them and the second is the difference between experimental laboratory studies and in vivo ecological studies, i.e., real life not the lab, and my speculation on what we will find we can do more of the latter.

To review a bit for the newer readers of my blog, the hippocampus (actually hippocampi, right and left) is a cortical structure which receives input of highly processed information from the posterior perceptual areas for processing as old or new, remembered or to be remembered, and feeds its results into frontal areas to support intentional guidance. It is one of my favorite areas for discussion so I have several blog posts on it over the years. It is an area between midbrain and cortex, so that is either at the peak of midbrain evolution and operates as the cortex for the limbic system, the emotional core of the brain or at the beginning of the neocortex and the evolution of the cerebral hemispheres and higher cognition.

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Hippocampus on the left side under the cut away cortex and on top of the limbic system

The Science News article focuses on studies with rats when mapping tonal sequences or time’s passage is important and a study with humans undergoing a computer simulation of hunting for a new home or job. The subjects interacted virtually with different characters and formed judgments about their power and approval of the subject. The interaction with the virtual characters correlated with activity in the hippocampus and upon further analysis, the judgments formed correlated with some behavioral traits associated with social anxiety. So imagine in the real world, going to a party with mostly familiars or with mostly strangers, we would imagine that our hippocampi would keep up with, i.e., map, the people we meet in different ways for strangers and familiars, that people with different social approaches, e.g., low or high social anxiety, introversion or extroversion, would map the interactions quite differently and subsequently remember the events quite differently.   So later on, say that night while sleeping, the hippocampi would consolidate particular memories of the party; they would extract the more salient experiences for memory input based upon their emotional stance.

The articles I read in Plosbiology are quite technical and I can only partially digest them. Still what I can glean there is interesting. They all used the electrical activity (EEGs of various sorts) to correlate with behavioral/mental activity. One looked at how the hippocampus grows quieter during REM (dream) sleep, where by quieter I mean more synchronized, i.e., less analysis going on, and with lower energies. This would seem to indicate that its role as memory organizer for input has momentarily paused while the selected memories are consolidated for later recall. Another article reports research showing that, contrary to current thinking and models, memory input-recall is done unconsciously as well as consciously. Many currently think conscious processing is needed for input and recall, though why I do not know. There is a lot of literature now showing that subconscious processes do much of the work—see Malcolm Gladwell’s book Blink for one perspective on this.

The third article is the most interesting to me because it shows differences between right and left hemispheres in detecting new information. Specifically the left hippocampus works more at detecting violations of expectations while the right hippocampal circuit monitors novelty and changes more generally. Are we using our left sided linguistic abilities to set and codify expectations for monitoring? Sure, look at the science about inner speech. Is the right side more concerned with the ongoing present, our consciousness being the remembered present (to use William James’ term)? Sure, look through my blog.

Now all these studies looked at the brain’s and the hippocampus’ response to events impacting our perceptual systems as set up by experimental designs. Leaving the strictly positivistic behind while still remaining empirically oriented I want to ask about functioning in the natural world (in vivo and ecological), about how we talk about hippocampal processing, and most especially, about the brain’s own creative processes that underlie artistic activity.

Consider how the hippocampus and its functions presumably develop early in life. Mostly immature at birth it quickly matures during the sensitive early years to acquire the ability to map space and time, things, and animate objects, not just people–remember toddlers’ affinities to other animals, especially dogs. These social maps, in conjunction with other areas such as the higher visual cortex for facial recognition and the lower limbic areas for attachment and emotional regulation, come to demarcate family and intimates from others, familiars from strangers and safety from danger. Imagine the impact on these incipient maps when intimates turn out to be dangerous as happens in instances of childhood maltreatment. Treasure the impact of healthy families on these same maps.

Consider what is actually being mapped here. Yes, experimental science, in order to progress in a sure-footed manner, must study aspects with careful controls. So studies have shown that the hippocampus maps space, time, things, and others. In a more holistic sense the hippocampus maps our experiences. Remember the patient H.M. (see post on ) who had a bilateral hippocampectomy, i.e., surgical removal of both hippocampi, in the effort to control severe epilepsy. He lost the ability to make new memories even though he could remember educational material and some events from his long past. He failed to recognize his doctors and other medical personal and the scientists studying his neuropsychological deficits even though he saw some of them almost every day, even though he had seen them an hour beforehand. He could converse and express himself on many topics and retained some procedural memories of how to do things. One conversation I find remarkable is reported in Joseph’s Neuroscience text. H.M. asked someone what he had done in the past little while because he was worried he may have done something wrong. He knew he had done something but he did not know what and so worried about that. His consciousness lacked the experience of the remembered present. (To my mind his worries mark him as a true gentleman as opposed to some politicians and sociopaths who worry about this not at all).

Consider what we do not know about hippocampal functioning during artistic endeavors such as dance, novels or music. I am quite sure that dancing, at least well with others, involves hippocampal maps for guidance. Ritualized and choreographed motions would necessarily involve maps for space, time, and others as well as procedural memories for the actual movements. Ritualized motion would summon emotional involvement in a consistent acculturated manner; modern choreographed motions would summon emotional involvement in a dramatic manner. What about novels with their virtual space, time, characters and experiences, all from different perspectives? Here I do not think we know much about how the hippocampus might function in support of the virtual domains involved and I do not think the hippocampus as a part of the perceptual-motor system dealing with objective events is sufficient for virtual operations. For these I think that dorsal and ventral loops involving longitudinal fasciculi in the cortex must contribute (see post Important stuff 2/11/16). So I wonder how Faulkner knew Yoknapatawpha County so well and how Gandalf and Aragorn knew all the paths of Middle Earth.

Finally consider music that I have focused on here so recently. Memory for tones, rhythms, melodies, beats seem basic and probably involve procedural memories as well. Memories for the biographical frames of favored songs are among the last to be lost with dementia, sometimes lasting even after one’s own identity is forgotten. This highlights again an important feature of hippocampal functioning, the setting of a standard or the stabilizing memory of the song’s emotional tone and echoes in a fashion analogous to its noticing things are out of place or out of order as reported in the previously cited studies and in H.M.’s worries. We experience only as we are able to fit moments together and this requires that we organize our mental functions coherently in an integrated fashion as moments in our life. Somehow our brains know what melodies work for a particular culture–no atonal tunes for me please–and some brains know innovative genius upon hearing; think of the responses to Stravinsky’s Rite of Spring.  So good job, hippocampus, and thanks for the memories.

How quick and subtle we are

When I worked as a speech-language therapist many years ago, I led parent workshops to help them understand and promote healthy language development. One facet of this was to present how complicated articulation was and how normal development of articulation varied a great deal. For example, many children say “tow” for “cow” early on in their speech development and self –correct (grow out of it) after some months. I always emphasized how complicated and how skilled a linguistic performance was. A common issue was how chronic ear infections affected development; speech is not easy to understand with the distortions resulting from middle ear congestion and from 6 months to 18 months, the brain is learning to process the auditory stream in a very specific manner in order to understand speech with facility. Likewise, speaking is a highly skilled behavior. A simple sentence, such as, “I want to go outside,” takes less than a second to utter and involves the articulation of around 14 phonemes, each requiring its own positioning of the vocal tract, i.e., lips, tongue, pharynx and larynx. Precise movements made in milliseconds with finely modulated breath control. Even our laughing is different from chimps’ laughing because of our breath control. I found it amazing that some 2 year olds, mostly girls, spoke with great clarity and was not amazed that some 4 year olds, mostly boys, still spoke with an errant phonemic pattern. speechsignal So speech is quick and subtle—I haven’t even broached topics of individual voice and interpersonal effectiveness and persuasion. (Remember Walter Cronkite saying, “And that’s the way it is” and we knew it was). And while we are discussing quick and subtle, let’s consider musical performance. I started reading Music, Language and the Brain by Aniruddh D. Patel, a comprehensive review of research on the topic. I can understand the linguistics and brain well enough but I struggle with some of the musical concepts. Dr. Patel discusses some research made possible by computer technology over the past decade or so into the timing of piano playing. Wow! Looking at one classical piano sonata, a researcher measured the length of all the eighth notes. Theoretically these are all of the same length and when computer reads a score, all the notes are the same, thus the flat, machinelike quality of some computer music. When a good pianist plays the score, however, the notes vary in length, with the average eighth note lasting 652 milliseconds with some lasting only 400 msecs and others going over 800 msecs. This variation is intentional as it results from the human player’s interpretation of the piece—these tiny variations convey the pianist’s musicality and expressiveness.  It is his  or her art. music-notes Other researchers manipulated musical pieces to approximate various degrees between very standardized computer plays to natural human performance. People were able to detect very subtle differences and always preferred the one closer to the natural performance. Yes, computers are fast and helpful; human art is quick and delightful. John Henry wins this one. Travel on.

WOW! A brilliant and difficult study

I saw over this holiday a few brief media reports of a study from Carnegie-Mellon that is quite different from what is usual. The research team placed subjects in an fMRI where they read on a screen one word at a time (every .5 seconds) from Chapter 9 of Harry Potter and the Sorcerer’s Stone (where he learns to fly a broom and has an early confrontation with Malfoy. As they did so the researchers monitored brain activity. Now this took 45 minutes and produced an enormous amount of data so these good folks developed a sophisticated computer program for its analysis. This is one of the first, if not the first, attempt to study the brain’s functioning during reading as it occurs in real life, which, as we know, is a very complex action. Oh wait, there is more.

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They were able to correlate brain activity to the segment read because of this design. The technical details here are really something and the computational aspect way over my head, but they had analyzed 195 features in the text, parsing out words, syntax, lexical features, presence of discourse, character identity, action, and emotion, word length, place in sentence string, and on and on, so that they would be able to see the brain’s response to these. The program learned to differentiate these features among the brain activity, so that afterwards, the program was able to differentiate which of two novel passages the subjects read with 75% accuracy by looking at their brain activity.

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Now some results were expected. Word length was processed in an occipital region, a visual area so no surprise there. Character actions were processed by areas such as the posterior temporal lobe and angular gyrus (close to Wernicke’s area) previously associated with detection of biological motion. (I bet mirror neurons were involved). Characters’ perspectives comprised of their intentions and feelings were processed by right parietal areas and these are known to be important for the theory of mind (what I would call the empathic understanding of another’s interiority). Working memory areas in bilateral temporal lobes were used to build up comprehension of the text as it was read word by word. They also found signs of bilateral syntactic processing normally associated with just the left side. And much, much more.   I may post on this again after digesting it longer but the methodology is spectacular and I am so impressed at their ability to carry it out. It will be very helpful in extending functional brain scans to more natural, real-lie activities. Their method for parsing language and resolving the temporal parameters of linguistic processing with brain activity is truly brilliant and a lot of work, I am sure. Most importantly it shows, even as rudimentary as it might be at this time, how diverse areas of the brain, front and back, right and left, participate in processing symbolic information of some intellectual complexity. (Think plot, action, character, feelings, discourse, and the language used to communicate it all. Why, pretty soon, they might find signs of why some fiction is better art). Again, I say, WOW!

To read the study please go to: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0112575

Conversation, music and novelty

In my 2/14/14 post I talked about the hippocampus, an evolutionarily older area of cortex.  Information from posterior perceptual areas flows through the hippocampus, which processes it for context and novelty, then sends the results forward.  A good example can be seen when a cat hears a noise, freezes and orients to check it out, and then moves forward figuring what the new situation is.

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Novelty is more complicated than might be supposed.  Perceptually it is detected when something changes or when something expected to change doesn’t change as expected.  The change may be about something static, e.g., an object, or dynamic, e.g., a stream of sound or passing scent.  Something uninteresting may change because of changes within the animal.  Figure may become ground or vice versa.  Perceptually we respond to ambient energies but that response is a very creative task.

Now we return to the 3/30/14 post about conversation.  The left side processes the semantic, syntactic, and phonemic information of a sentence while the right processes the intonation or the prosody of the utterance.  What comprises novelty here is made even more complicated because we are creating the information as we make meaning, because the grammatical and pragmatic information pose different challenges but must be integrated, and because of the rapid and ephemeral exchange composing the communication.

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Maybe the hippocampi, right and left, are involved in this, but more likely higher cortical areas come into play as we understand a comment on a topic and then make our own new comment and then carry on, maybe even changing topics again while monitoring the interpersonal prosody for such things as changes in tone for sarcasm, excitement, joy, sorrow, etc.

An interesting feature of this processing comes when considering H. P. Grice’s 4 conversational maxims of quantity, quality, relevance, and manner.  Briefly, when conversing we expect people to say not too much or too little, to be clear, to be on topic and to be genuine.  These are probably not so much maxims as dimensions shaped by assumptions, so that when we detect a violation, that constitutes novelty.  When we hear a crash from the next room and ask our child what happened and he answers, “Nothing,” that is too little.  When someone goes off topic or becomes tangential or speaks unclearly or sarcastically or (we suspect) disingenuously we may interrupt and intervene to further successful communication.  Novelty of a different and rarefied sort.  Now on to music.

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Daniel Levitin in his book, This is Your Brain on Music, explains how new and old patterns or gestalts are important for music on several levels.  Different cultures have different musical keys which set up our expectations.  The progression of notes and tempo set up expectations which a skilled composer can exploit in order to express different feelings or concepts.  Our memory is important in catching on to the variations of themes.  A performer’s musicality depends in part upon their ability to vary timing and emphasis, etc., a fresh counter to the staid black and white score.  So novelty comes in various forms and guises, each important to the communication of symbolic import through the specialized channels of the MEMBRAIN.   Now this is getting interesting.  Next up?  Either my quibbles with Levitin or an introduction here to the arcuate fasciculus.

Conversation, music, culture and the membrain

No, I spelled it the way I need to spell it, MEMBRAIN.  I may not have been as clear or explicit as I would have liked below (and you may not feel the need to scroll down through all of this) so let me be so now. If it is in the mind, it got there through the brain.  What we are conscious of or our subjective domain or what some  call our interiority is created and maintained by the MEMBRAIN.

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The MEMBRAIN, like all membranes so important to life, keeps the inside in and the outside out and then selectively passes energy and material in and out.  Like Dr. Who’s TARDIS, the MEMBRAIN’S interior is larger than its exterior, a lovely feature perhaps in order to mirror the universe in which we live and learn and imagine.  Counter to what most consider goes into the mind, even though our consciousness seems dominated by perceptual stimuli from outside our body and its brain, our interior is also filled with energy (read information) from within our body and brain.  But again, if it is in our mind, it came through the MEMBRAIN, and if it comes out of our mind through behavior, including especially symbolic expression, it came out through the MEMBRAIN.  Specialized channels for language and art forms, e.g. music, have evolved for the human MEMBRAIN, and when such symbols come to be shared in a socialized reality, we have culture.

That said, let’s look at how conversation and music have changed culturally.  One of the conversational maxims articulated by H. P. Grice back in the 1960s was that conversation must be informative.

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Seems like a basic feature, but some people and some cultures consider the information they hold within as private and personal property, not to be shared lightly, analogous to some people in some cultures disliking having their photograph taken.  It steals their image and is not proper.  So in some cultures or in diplomatic circles or poker games, conversations are not as informative or straightforward as they could be.  One virtue of science, then, is the effort to convey information with transparency so that others may  judge the full truth of the matter.  The point here is that we  control the permeability of the MEMBRAIN.

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I have recently finished reading This is Your Brain on Music by Daniel Levitin, an interesting and informative book (more later on some interesting points and also my quibbles with it).  He points out, as others like Angelique Kidjo have done, that music originally was, and in many cultures and moments still is, participatory.  The performer-audience gig did not arise until a few hundred years ago after many millennia of music making.  (Levitin points out that bone flutes are some of the earliest artifacts of Homo). This frames early music as a sort of simultaneous conversation, everyone listening and playing at once or in a call-response/verse-chorus form.  Just listening without participating was a rather prominent cultural change and the MEMBRAIN functions differently, letting energy in and keeping energy in rather than expressing it outwardly.

As an final aside here, when I began working with preschoolers as a speech-language pathologist, I observed many story time circles (or singing circles etc.).  Children have learned language through conversation (you listen and respond in ongoing and rapid fashion) and have then to learn how to listen audience fashion as the teacher reads a book, a basic attention span skill for our systems of education.  More recently I saw a video of a Buddhist school in which the students all shouted and talked at once as they debated fine points of their teachings, quite a different model for educational discourse.  All acquiring MEMBRAIN skills for sustaining our interiority.