November 2: Mammalian Heritage Day

Finally a fake holiday I can get behind. We humans in our evolution find ourselves benefitting fully from our mammalian heritage. Mammals appeared on the scene around 500 million years ago and have diversified into many different forms since. Consider their (our) primary characteristics. Being warm blooded confers a crucial independence from ambient conditions, an independence humans have taken to an ultimate degree. It is not just that mammals have adapted to many different environments around Gaia, including returning to the ocean, but we have further enhanced our independence by controlling and changing these ambient conditions, perhaps to own detriment but then no species continues forever.

Consider another characteristic: live births. This is especially important for three reasons. First, infants born viably but immaturely permit an incredible amount of post-partum growth. The benefits of this are astounding: increased brain growth and size and critical periods of maturation where experience affects brain development in deep ways. Second, parenting becomes a lot more than regurgitating food into infant mouths and then kicking them out of the nest. Oxytocin, a most important hormone for parenting energy and prosocial behaviors, has been around, according to some estimates, for over 530 million years. Over the course of evolution mammalian brains developed the capacity to respond more powerfully to this hormone—parenting and family life became more prominent in any adaptive success, and that leads us to the third reason: If you want to raise more intelligent children and pass on to them the benefits of prior generations’ experience, birth them live and immature, maintain a nurturing family structure, and extend their juvenile period so that they do not begin to reproduce until they are a decade or so old. The discovery of controlling fire was not really that big of a deal; the passing on of this technique, however, was; just ask Prometheus.

Our immediate (relatively speaking) ancestors who showed the culmination of these characteristics are the primates who appeared around 53 million years ago. That means mammals evolved for 450 million years before our large brained, visually oriented, socially engaged, and quick intelligence kinfolk appeared and then simians appeared a few million years after that. Our line split off from the great apes around 8 million years ago and our partners, the dogs, appeared around 3 million years ago. Fire was important because it furthered this trend. Cooking food releases more calories, making digestion more efficient, and more energy from food powers increased brain capacity. Fire warms us and draws the family group to the hearth. Civilization began at the hearth (and it looks like it will die in committee).

So this November 2 take a moment to reflect on our genetic heritage and thank a mammal, any mammal, all mammals for continuing this genetic stream and tend to your hearth.


We sing a song of mammals today . . .

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.


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.

Intimacy and MEMBRAIN 2.0: ripening and bruising

I have been thinking more about the MEMBRAIN with its intimate functioning and its risk of disruption (think recent news reports of sexual assaults on campus). Imagine a head of cauliflower, how it develops up from the stem, expands through the addition of increasingly differentiated flowerets, and then ripens as a model of the brain. The growth follows two gradients, first from the inside out and of course, bottom to top.


Looking at the ‘brain’ from the bottom we can see how its growth spreads and expands through differentiated tissues. Our brains start with a neural tube from which all the nerve and glial cells emerge and then travel to their assigned place; the tube ends up being the ventricles wherein cerebral-spinal fluid is made to bathe the cells in nutrients. At the head of the tube the midbrain and cerebrum form with all their lobes and wrinkles.


Imagine further that different vertical structures operate with different neurotransmitters, so that some of the ‘florets’ are one color and some another, some fire up quickly in passing and some slow and sustained, and then further that ‘floret’ tops communicate with each other through long fibers front and back (green bands), left and right (commissures). Get the picture? (Yes, we see).


As stated in the last post, intimacy involves very open MEMBRAIN functions, much is let in and out, not much is kept in or out. This permeability is managed through the arousal (and then the attentional) system that initiates from a central structure and goes up into the cerebrum. That is the red circle at top. Indeed, when you watch an fMRI you can see the intensity of arousal rising up through the middle and then spreading out as the lateral systems begin to process front and back, left and right.


We start our intimate journey at the outset with our parents when our brains are beginning to ripen, i.e., mature. When we attach and bond with them we are using and developing lower and central structures and because the right side matures earlier than the left, we are also using our right hemisphere more. The mother-child communication is done with the right side of the brain.


These experiences are important for oh so many reasons, particularly because this helps us develop our control of emotional arousal and thus MEMBRAIN permeability. Wow! And later, as the left hemisphere comes into its own, the child learns to attend to fine motor tasks while ensconced in a safe, nurturant and guiding relationship.

Father child

Now some early events can bruise the ripening fruit and affect its subsequent development, subtly affecting its capacity for intimacy. Should the mother become unavailable through emotional difficulties, illness, substance abuse, physical absence (think military deployment), or death, this loss can affect how the brain ripens. Likewise, trauma, especially family violence and sexual abuse, bruises the brain and this bruise can be seen in the deficient development of emotional control and the subsequent compromise of intimacy. And this is important because we start by developing our intimacy capacity as we travel on to develop our intellectual abilities.

Consider two features of children with attachment disorders and/or an early history of family based trauma. The first is that they want constantly and this want is rarely satisfied. The parent (figure) can give and give but the child does not take it in really; their MEMBRAIN is impervious to affection and its manifestations. You give them a hug and they want more or something else or you hugged another child so . . . or you give them shrimp and they want steak or . . .you get the idea. This emotional coldness extends to their own lack of empathic consideration for others. The second is that they do not operate with sequential reasoning very well and this includes responsibility for their own actions. Parents can watch the child’s misbehavior directly and then grow exasperated when the child denies its actions. When working with them therapists (and parents) have to back up a step and teach them to think in story board form like a comic strip, e.g., this follows from this and that follows from that. Their intellectual grasp of these matters was compromised when the MEMBRAIN was bruised early on.

The violation of intimacy by males sexually assaulting females is related to this and I will say more later about that, but I am also getting an itch to talk about other topics. So long for now.