Artificial Neural Nets and Learning

This article, Artificial Neural Nets Finally Yield Clues to How Brains Learn, appeared a few months in Quanta Magazine and never got around to commenting on it until now. It has this image is in it.

The article is primarily about something called backpropagation as a technique for improving neural nets. At the The article says:

Models developed independently by Kording in 2001, and more recently by Blake Richards of McGill University and the Quebec Artificial Intelligence Institute and his colleagues, have shown that pyramidal neurons could form the basic units of a deep learning network by doing both forward and backward computations simultaneously. The key is in the separation of the signals entering the neuron for forward-going inference and for backward-flowing errors, which could be handled in the model by the basal and apical dendrites, respectively. Information for both signals can be encoded in the spikes of electrical activity that the neuron sends down its axon as an output”.

The issue is whether something like backpropagation is actually happening in brains, especial in the pyramidal neurons. Even the researchers discussed in the Quanta article think they still need to explain something. Unfortunately, it doesn’t seem likely the neurons are actually running backpropagation algorithms. ” For a variety of reasons, backpropagation isn’t compatible with the brain’s anatomy and physiology, particularly in the cortex”. So, they are looking for other techniques to accomplish the same.

Where have we seen pyramidal neurons before?

There is this paper that I wrote two posts about a while ago that states: “This perspective makes one quite specific prediction: cortical processing that does not include L5p neurons will be unconscious. More generally, the present perspective suggests that L5p neurons have a central role in the mechanisms underlying consciousness”.

There is also the Susan Pockett electromagnetic theory of consciousness with this diagram of pyramidal neurons in the layers of the brain.

Her theory: “The hypothesis proposed here is that one necessary (albeit clearly not sufficient) characteristic of conscious as opposed to non-conscious EM fields or patterns of charge is a spatial structure something like that shown… The essence of the proposal is that in the radial direction (perpendicular to the surface of the cortex) conscious fields will have a surface layer of negative charge above two deeper layers of positive charge, separated by a distinct neutral layer.”

Is the missing part of the explanation feedback generated by the brain electromagnetic field?

There is an entire post I wrote on learning and consciousness that argues, in part, for  Stephen Grossberg’s Adaptive Resonance Theory. I submitted a comment on the Quanta article:

Baars, Grossberg, and others have pointed out the role of consciousness in any sort of complex learning. Grossberg almost equates learning and consciousness and his description matches what this article is discussing.

“The processes whereby our brains continue to learn about a changing world in a stable fashion throughout life are proposed to lead to conscious experiences. These processes include the learning of top-down expectations, the matching of these expectations against bottom-up data, the focusing of attention upon the expected clusters of information, and the development of resonant states between bottom-up and top-down processes as they reach an attentive consensus between what is expected and what is there in the outside world. It is suggested that all conscious states in the brain are resonant states and that these resonant states trigger learning of sensory and cognitive representations.

So the missing piece seems to be consciousness itself or exactly how it works.

To my surprise, Stephen Grossberg himself responded.

Thanks for noting that the authors seem not to be aware that many of their aspirations have been realized years ago through the work that I, with many gifted collaborators, have carried out during the past 40 years. See for downloadable lectures and articles that illustrate this progress. One problem with their models is that their foundational hypotheses are incompatible with thousands of known experimental facts about how our brains make our minds. A second problem is that the authors’ models do not explain any of these facts. In science, the theories that warrant attention are the ones that successfully explain and predict the most facts in a principled and testable way. The theories that I have been lucky enough to develop over the past 40 years past that test. Stephen Grossberg

Grossberg thinks backpropagation isn’t required as an explanation. He believes his Adaptive Resonance Theory solves all of the problems that backpropagation is trying to solve without entering into any problems that backpropagation creates. In one of his presentations he writes: “These efforts to overcome catastrophic forgetting created additional conceptual and computational problems I view them as adding EPICYCLES to ameliorate a fundamental flaw in the model reminiscent of adding epicycles to correct problems in the
Ptolemaic model of the solar system. The Copernican model that we now accept did not require epicycles”!

Posted in Consciousness, Electromagnetism, Human Evolution | 4 Comments

Veridical OBEs and NDEs?

We can never prove that the consciousness of somebody at some time might have left their body in some way and gained access to knowledge otherwise unavailable. It’s impossible to prove a negative. On the other hand, the evidence that this has ever happened is virtually non-existent despite the anecdotal accounts that circulate and recirculate through papers, books, and videos.

I’m talking about out-of-body experiences (OBEs) and the special cases of out-of-body of experiences that occur near death (NDEs). There is no disputing these experiences occur. Psychologically healthy, normal people do on occasion have the experience they are outside their body. Some people have them frequently and a few can produce the experience on demand. The prototypical OBE account involves having the sensation of leaving the body and staring down at their physical body from an above position frequently near the ceiling. The NDE may or may not include an OBE but will usually include additional experiences, such as traveling through tunnels, meeting dead relatives, life review, and meetings angels. The claimed veridicality of the OBE portion of the NDE is frequently used as supporting evidence that we have a consciousness that persists after death. While NDEs take place in situations involving extreme bodily stress, frequently cardiac arrests, overall there is considerable overlap between both phenomena.

This is the subject of Seeing Myself: The new science of out-of-body experiences by Susan Blackmore. The book covers not only the historical research of OBEs but importantly covers a great deal of modern neuroscience regarding them. Despite the widespread mystification of these experiences in many quarters, we are surprisingly close to understanding in a scientific way what exactly is happening in the brain during them. This research begins to shed light on how we create and maintain our sense of self.

Blackmore herself is uniquely qualified to write this book. Originally a parapsychological researcher, she actually had a significant OBE that drove years of effort on her part to demonstrate the reality of paranormal phenomena. After years of research and examination of evidence, she found herself forced to conclude there was no evidence for any of it. Despite this change in views, she has not transformed into a cynical materialist scientist. She considers herself a neutral monist, which means she thinks there might be an ultimate reality but we can’t be sure exactly what it is made of. Additionally, she has spent decades in training in various spiritual traditions, primarily Zen, and is a leading proponent of secular spirituality.

Blackmore’s start and end points parallel closely my own thinking on this subject. Originally a believer in the paranormal, I once did a high school project that tried to replicate some of J. B. Rhine’s experiments. My results, much like Rhine’s, were almost off-the-chart in statistical significance. I’m quite certain now that my controls were inadequate and likely even my understanding of the statistics was wrong. These seems to be endemic problems in the field, although probably not quite as acute as in my efforts. As the years have passed, I’ve grown increasingly skeptical on the paranormal until now I am much in the same place as Blackmore. Despite this view, I continue to believe there is some value in spirituality, some significance to what seems like the miracle of consciousness itself.

Blackmore’s book covers the gamut of the out-of-body experiences. Actually there are four types of distortions of self and body image that seem to arise from various types of uncontrolled firings and misfirings in different parts of the brain. The classical out-of-body experience involves the sensation of a self disconnected from the physical body that may or may not have a body itself (usually called the “astral body” in the classical literature on the subject). Autoscopy is when a person in his/her own body has the hallucination of seeing his/her own double. Heuautoscopy is much like autoscopy but the person has the feeling of being in his/her body but also being in the body of a double or sometimes in multiple other bodies. The simplest and possibly most common form of distortion is a feeling of a presence. While possibly subject to other interpretations, Blackmore thinks the presence that is felt is actually a distorted image of one’s own self that is sensed to be behind or surrounding the body.

The feeling of presence can be somewhat reliably reproduced with Michael Persinger’s God helmut that provides magnetic stimulation to the temporal lobes. The classical OBE and various other body distortions can be reproduced by stimulating the temporoparietal junction (TPJ). The TPJ is the point where the temporal lobes on each side of the brain and parietal lobe at the back of the brain meet. Blackmore writes that it is “deeply implicated in building up our sense of self”. Wilder Penfield working with epileptics induced an OBE by stimulating the area and Dirk De Ritter replicated the phenomenon in 2007 while trying to cure a man of tinnitus.

Blackmore’s theory is straightforward. OBEs are the result of uncontrolled firings in various neural circuits that are responsible for our body image and sense of self. These are primarily in the temporal lobe and TPJ. They can be induced by direct stimulation in experimental settings, caused by lesions and other abnormalities in the brain, or triggered by various drugs or other stresses, such as anoxia during cardiac arrest. Uncontrolled firings in the visual and auditory context can also account for reported noises and tunnel travel associated with NDEs and OBEs.

Let’s suppose Blackmore’s theory, even in incorrect in certain details, is broadly correct. Could it still be possible that consciousness can in some way exist outside of the body? Perhaps the neuron firings are simply correlates of consciousness outside the body. Neurons fire when we see an apple hanging from a tree. Maybe they fire, but fire differently, when our consciousness is perceiving something outside the body.

What would be the evidence? This is where we come to the point that we can’t disprove it hasn’t ever happened but we can’t find any evidence for it either.

In all of Blackmore’s survey of classical OBE experience – Sylvan Muldoon, Oliver Fox, Robert Monroe – there is no account of obtaining knowledge during astral projection that is sufficiently specific or that cannot to be accounted for in other ways. What’s more, the OBErs in their own accounts acknowledge getting a significant amount wrong. Some have developed theories about how and why the astral world is different from the physical world to explain why what they see in the astral world doesn’t match the physical. With NDEs, we find the same. She surveys some of the most promising cases – Pam Reynolds and Maria and the shoe – and finds no conclusive evidence. What clouds many of these cases are the possibilities for false memories. People may merge information gained before or after the NDE with the NDE itself. In other cases, people may simply be awake or aware enough to gain information about what is happening to them during resuscitation. Prospective studies, such as the AWARE project, haven’t turned up anything either. These studies involve seeding operating rooms with images and messages that can only be seen from the ceiling. If someone has an NDE and can report the message, it would be close to conclusive proof of veridical out-of-body experience AWARE only produced two NDEs and only one seemed to have an experience outside the body, but unfortunately it occurred in an OR that didn’t have an image or message. Even the main author of the study says the report of that one person wasn’t conclusive. What the single individual reports doesn’t seem exceptional and could have been information gathered before or after the NDE or even during the resuscitation.

The NDE accounts floated in books and through the Internet frequently carry the claim that the NDE with veridical experience occurred while the brain was dead – that is, there was no detectable brain activity. Taken literally this can’t be true. If the brain is completely dead, the person is dead. They can’t be resuscitated. Even with people near brain dead, in most cases, there is no way to verify there is no electrical activity because people undergoing resuscitation or even operations are not connected to sensitive enough equipment to verify there is no activity. Nevertheless, an experiment on mice demonstrated that the dying brain is still active. Even more to the point, an experiment on humans who were terminally ill and had life support withdrawn demonstrated the same thing.

In each case, loss of blood pressure, as monitored by indwelling arterial line, was followed by a decline is BIS/PSI activity followed by a transient spike in BIS/PSI activity that approached levels normally associated with consciousness.

We further speculate that since this increase in electrical activity occurred when there was no discernable blood pressure, patients who suffer “near death” experiences may be recalling the aggregate memory of the synaptic activity associated with this terminal but potentially reversible hypoxemia.

These spikes are temporally associated with the loss of measurable blood pressure, and immediately after the spike, the BIS/PSI signal drop to zero and the patient is soon pronounced dead. The BIS spikes last for a few minutes at maximum, but usually last between 30–180 seconds.

It would be a comfort to many, I’m sure, if our consciousness could exist outside our bodies and survive death. Unfortunately there doesn’t seem to be really any evidence for it.

Posted in Consciousness, Mysteries | 6 Comments

Electromagnetism Is a Property of Spacetime Itself

This is an interesting article, although I’m not sure I understand all of the ramifications of it.

The link between general relativity and electromagnetism becomes clear by assuming that the so-called four-potential of electromagnetism directly determines the metrical properties of the spacetime. In particular, our research shows how electromagnetism is an inherent property of spacetime itself. In a way, spacetime itself is therefore the aether. Electric and magnetic fields represent certain local tensions or twists in the spacetime fabric.

It means that the material world always corresponds to some geometric structures of spacetime. Tensions in spacetime manifest themselves as electric and magnetic fields. Moreover, electric charge relates to some compressibility properties of spacetime. Electric current seems to be a re-balancing object, which transports charge in order to keep the spacetime manifold Ricci-flat.

Posted in Electromagnetism | 18 Comments