28/11/2009 by admin.

ScienceDaily reports on the work of L. Chittka (here) on the relationship between brain size and complexity.

“Research repeatedly shows how insects are capable of some intelligent behaviours scientists previously thought was unique to larger animals. Honeybees, for example, can count, categorise similar objects like dogs or human faces, understand ’same’ and ‘different’, and differentiate between shapes that are symmetrical and asymmetrical…. We know that body size is the single best way to predict an animal’s brain size….The size increase allows the brain to function in greater detail, finer resolution, higher sensitivity or greater precision: in other words, more of the same….In bigger brains we often don’t find more complexity, just an endless repetition of the same neural circuits over and over. This might add detail to remembered images or sounds, but not add any degree of complexity. …This must mean that much ‘advanced’ thinking can actually be done with very limited neuron numbers. Computer modelling shows that even consciousness can be generated with very small neural circuits, which could in theory easily fit into an insect brain. In fact, the models suggest that counting could be achieved with only a few hundred nerve cells and only a few thousand could be enough to generate consciousness.”

I believe that this may be a slight over simplification. For a particular kind of animal, after correction for body size, brain size predicts intelligence. It is just that intelligence does not relate to brain size across different types of animal. Also the body size correction must be made. Of course intelligence would have something to do with level of detail, resolution, precision etc. and that relationship would follow brain size within a particular brain architecture. But a particular capability (without reference to its resolution) would not be related to brain size. In that case all animals could have some degree of consciousness.

There is a quote mistakenly attributed to Stalin or Lenin but said by David Glantz about the WW2 Soviet army, “Sometimes, quantity has a quality all its own”. This is probably true of brains.

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25/11/2009 by admin.

Anthropology.net has (here) a part of a discussion with Michael Gazzaniga. This bit is about responsibility.

“I did want to come back to the one point on the free will thing because I just think it’s a kind of a red herring. People talk about free will, you should return the question and say free from what, what are you talking about?

I mean what we all are, are information gathering organisms that have learned through a life’s experience what to do, what not to do, what’s good, what’s bad, does this payoff versus that payoff? And when a new situation presents itself we call upon our knowledge of the world from past experience to decide what to do. And that decision goes on through mechanisms of the brain, and once the brain decides, based on all your past experience, to do something, you want it to do it right. It’s not clear to me what free will means in that way of knowing that we have all these automatic processes that are going on in the brain that we’ve trained through time.

I think how you think about it is that personal responsibility, which is a key concept in our culture, is alive and well because it really isn’t in your brain, it’s in the social rules of a group. So think of it this way, if you’re the only person in the world, the concept of personal responsibility means nothing. Who are you responsible to? If there are two people to six billion, all of a sudden the rules develop. If we are going to socially interact, which is crucial for the human condition, we are going to have these rules. Almost everybody—you’d have to be extremely neurologically compromised—almost everybody can follow a rule.”

What excellent good sense!! Stop worrying about whether our decisions are free and start worrying about whether they are appropriate.

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22/11/2009 by admin.

ScienceDaily has a report (here) on research by L. Colgin and group as published in Nature.

Colgin and her colleagues measured brain waves in rats, in three different parts of the hippocampus, which is a key memory center in the brain. While listening in on the rat brain wave transmissions, the researchers started to realize that there might be something more to a specific sub-set of brain waves, called gamma waves. Researchers have thought these waves are linked to the formation of consciousness, but no one really knew why their frequency differed so much from one region to another and from one moment to the next.

Information is carried on top of gamma waves, just like songs are carried by radio waves. These “carrier waves” transmit information from one brain region to another. “We found that there are slow gamma waves and fast gamma waves coming from different brain areas, just like radio stations transmit on different frequencies,” she says. …

“When brain cells want to connect with each other, they synchronize their activity. The cells literally tune into each other’s wavelength. We investigated how gamma waves in particular were involved in communication across cell groups in the hippocampus. What we found could be described as a radio-like system inside the brain. The lower frequencies are used to transmit memories of past experiences, and the higher frequencies are used to convey what is happening where you are right now.”…

“The cells can rapidly switch their activity to tune in to the slow waves or the fast waves,” Colgin says, “but it seems as though they cannot listen to both at the exact same time. This is like when you are listening to your radio and you tune in to a frequency that is midway between two stations- you can’t understand anything- it’s just noise.”…

“This switch mechanism points to superfast routing as a general mode of information handling in the brain,” says Edvard Moser, Kavli Institute for Systems Neuroscience director. “The classical view has been that signaling inside the brain is hardwired, subject to changes caused by modification of connections between neurons. Our results suggest that the brain is a lot more flexible. Among the thousands of inputs to a given brain cell, the cell can choose to listen to some and ignore the rest and the selection of inputs is changing all the time. We believe that the gamma switch is a general principle of the brain, employed throughout the brain to enhance interregional communication.”

It looks like there may be yet another dimension to communication in the brain.

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19/11/2009 by admin.

Jonah Lehrer interviewed Andrew Koob on the Scientific American site (here) about the importance of astrocytes, one type of glial cells. It seems that we will not have even a rough idea of how thought works until we understand these cells.

Interestingly, as you go up the evolutionary ladder, astrocytes in the cortex increase in size and number, with humans having the most astrocytes and also the biggest. … cell counts in the brain revealed glial cells to be nearly 90% of the brain (this is where the neuron based idea that we only use 10% of our brain comes from). … many researchers have completed experiments on the communicatory ability of glial cells with neurons … it was discovered glial cells respond to and release ‘neuro’ transmitters. … calcium waves are how astrocytes communicate to themselves. Astrocytes have hundreds of ‘endfeet’ spreading out from their body. They look like mini octopi, and they link these endfeet with blood vessels, other astrocytes and neuronal synapses. Calcium is released from internal stores in astrocytes as they are stimulated, then calcium travels through their endfeet to other astrocytes. The term ‘calcium waves’ describes the calcium release and exchange between astrocytes and between astrocytes and neurons. Scientists at Yale, most notably Ann H. Cornell-Bell and Steven Finkbeiner, have shown that calcium waves can spread from the point of stimulation of one astrocyte to all other astrocytes in an area hundreds of times the size of the original astrocyte. Furthermore, calcium waves can also cause neurons to fire. And calcium waves in the cortex are leading scientists to infer that this style of communication may be conducive to the processing of certain thoughts. … In this theory, neurons are tied to our muscular action and external senses. We know astrocytes monitor neurons for this information. Similarly, they can induce neurons to fire. Therefore, astrocytes modulate neuron behavior. This could mean that calcium waves in astrocytes are our thinking mind. Neuronal activity without astrocyte processing is a simple reflex; anything more complicated might require astrocyte processing.

This just shows how far we are from understanding the brain.

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16/11/2009 by admin.

Fairly often we hear philosophers explaining how it is that a scientific theory of consciousness is a goal that can never, in principle, be reached. Eric Schwitzgebel has his version (here). His has three simple steps:

(first) No general theory of consciousness can be justified except on the grounds that it gets it right about certain facts known independently of that theory. Those facts include facts about the presence or absence of conscious experience in a wide variety of actual and possible beings that are unlike us in potentially relevant respects — beings like frogs, insects, weird sea life, computers and robots of various types, alien beings of various types, and collective super-organisms of various types.
(second) Independently of a well-justified theory of consciousness, we cannot know, with regard to most such beings, whether consciousness is present or absent.
(third) Therefore, no general theory of consciousness can be justified.

This is not how scientific theories are created or accepted. There is no rule that says that a theory must be correct about facts that are independent of the theory. Plate tectonics did not need an independent test planet to be accepted; quantum mechanics did not need another universe. Scientists like a theory to be falsifiable, at least in principle, or to have a pretty high Baysian probability. But the real test is whether, taking everything together, the theory is convincing to the scientists in that area of research.

What happens is that a lot of facts and little local theories accumulate and then they collect into larger groups and with luck into one big theory. Thousands of experiments and observations pave the way. New ways and machines to observe are invented. In this process, the terms (the words) involved change their meanings, split in two, merge, become analogies of other terms in other theories. For it is not the words that are important; it is the physical reality that is important and the words are just tools to describe a particular model of reality. The sub-questions that seem to need answers appear and disappear as understanding increases. The arrogance of someone saying that no general theory of consciousness can be found and saying this before the science is more than out of the gate, is mind-boggling.

But then there are always people who would sooner play silly, entertaining word games, then have a deep understanding of something.

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13/11/2009 by admin.

E. Callaway has an article in the New Scientist on how people relate to their avatars or virtual selves compared to their real selves (here). Again, it seems that our sense of self is not exactly what we would expect.

Brain scans of avid players of the hugely popular online fantasy world World of Warcraft reveal that areas of the brain involved in self-reflection and judgement seem to behave similarly when someone is thinking about their virtual self as when they think about their real one. … Previously, researchers have observed that people easily adopt the persona of their virtual selves, for instance, by acting more aggressively when their avatars are tall than when they are short, irrespective of an individual’s height in the real world. … When K. Caudle looked for brain areas that were more active when volunteers thought about themselves and their avatars compared with real and virtual others, two regions stood out: the medial prefrontal cortex and the posterior cingulate cortex. That makes sense as prior research has linked the medial prefrontal cortex to self-reflection and judgement. … They found activity differed in a region called the precuneus, implicated in imagination.

The precuneus is also interesting. It is tucked inside the central fold in the cortex alone the medial wall and therefore has not shown on EEG waves or many lesion studies and has been somewhat overlooked. It appears to be involved in a variety of high level cognitive functions, including episodic memory, self-related processing and aspects of consciousness. It is part of the default mode network and so may be important in daydreaming as well as real world activities.

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10/11/2009 by admin.

In August I posted an item on Blanke’s experiments with out-of-body experiences (here). Since then Anil Ananthaswamy has a article in the New Scientist on the subject. (here).

Out-of-body experiences are usually associated with epilepsy, migraines, strokes, brain tumours, drug use and even near-death experiences. .. (but) … about 5 per cent of healthy people have one at some point in their lives….So what exactly is an out-of-body experience? A definition has recently emerged that involves a set of increasingly bizarre perceptions. The least severe of these is a doppelgänger experience: you sense the presence of or see a person you know to be yourself, though you remain rooted in your own body. This often progresses to stage 2, where your sense of self moves back and forth between your real body and your doppelgänger. … Finally, your self leaves your body altogether and observes it from outside, often an elevated position such as the ceiling. “This split is the most striking feature of an out-of-body experience,” says Olaf Blanke. … Some out-of-body experiences involve just one of these stages; some all three, in progression. Bizarrely, many people who have one report it as a pleasant experience. So what could be going on in the brain to create such a seemingly impossible sensation?

From various experiments, the area of the brain responsible seems to be the temporoparietal junction (TPJ).

This makes some kind of neurological sense. The TPJ processes visual and touch signals, balance and spatial information from the inner ear, and the proprioceptive sensations from joints, tendons and muscles that tell us where our body parts are in relation to one another. Its job is to meld these together to create a feeling of embodiment: a sense of where your body is, and where it ends and the rest of the world begins. Blanke and colleagues hypothesised that out-of-body experiences arise when, for whatever reason, the TPJ fails to do this properly.

The TPJ is active when people imagine they are in a position different from their actual orientation.

This does not, however, explain the most striking feature of out-of-body experiences. “It’s a great puzzle why people, from their out-of-body locations, visualise not only their bodies but things around them, such as other people,” says Brugger. “Where does this information come from?”…(in) circumstances you are conscious of a sensation of movement, yet your brain is aware that your body cannot move. In an attempt to resolve this sensory conflict, the brain cuts the sense of self loose . “It resolves by splitting the self from its body,” says Cheyne. “The self seems to go with the movement and the body gets left behind.” Perhaps similar sensory conflicts cause classic out-of-body experiences.

Metzinger does have a suggestion. Imagine an episode from a recent holiday. Do you visualise it from a first-person perspective, or from a third-person perspective with yourself in the scene? Surprisingly, most of us do the latter. “In encoding visual memories, the brain already uses an external perspective,” says Metzinger. “We don’t know much about why and how, but if something is extracted from such a database [during an out-of-body experience], there may be material for seeing oneself from the outside.” … To address that question, Metzinger has teamed up with Blanke and his colleagues in an experiment that induces an out-of-body experience in healthy volunteers. They film each volunteer from behind and project the image into a head-mounted display worn by the volunteer so that they see an image of themselves standing about 2 metres in front. The experimenters then stroke the volunteer’s back - which the volunteers see being done to their virtual self. This creates sensory conflict, and many reported feeling their sense of self migrating out of their physical bodies and towards the virtual one.

Interestingly people claim to have seen themselves and others around them in the area while they had their eyes closed through the whole experience. So it is likely that the experience is created from bits of memories.

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07/11/2009 by admin.

A little while ago Jonah Lehrer (here) posted a blog on the work of A. Damasio and A. Bechara.

Why would being able to count your heartbeats lead to better performance at a card game? The answer tells us something interesting about the “body loop,” and the importance of eavesdropping on those subtle emotions reverberating through our flesh. As William James hypothesized back in 1882, every emotion begins as a series of physiological changes in the body; our metaphysical feelings have a very carnal source. “What kind of an emotion of fear,” James wondered, “would be left [after seeing a bear in the woods] if the feeling of quickened heart beats nor of shallow breathing, neither of trembling lips nor of weakened limbs, neither of goose bumps nor of visceral stirrings, were present?” James’ answer was simple: without the body there would be no fear. We need the body in order to feel.

Damasio believes that emotion has a central role in rational thought. Feelings are indispensable.

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04/11/2009 by admin.

E. Morsella’s theory (here) continued from the last post:

…it is no longer useful to claim that conscious processes are simply more complex, controllable, planned, decision-like, or action-like than unconscious ones. Nor is it useful to propose, as suggested by the integration hypothesis, that unconscious processes are incapable of integrating different kinds of information, for … various kinds of interactions can occur unconsciously. Why can interactions occur unconsciously for the ventriloquism effect, binocular rivalry, the McGurk effect, and the other phenomena … but not for conflicts involving tissue damage, air intake, or consummatory behavior? As explained in the theory presented below, it is because the latter conflicts require information-processing structures having different, high-level concerns, an anthropomorphic term that warrants a precise definition.

…what distinguishes conscious from unconscious concerns reflects not the nature of the sensory afference, predictive capacity, or memory demands involved, but rather the nature of the effectors involved: A common property of the response tendencies presented is that they can all be realized in terms of skeletal muscles plans… supramodular response systems are unique in that their outputs may potentially conflict with each other regarding skeletal muscle plans. …phenomenal states cull simultaneously activated response tendencies to yeild a single, adaptive skeleomotor action… in evolutionary terms, conscious processes served to mediate large-scale skeletomotor conflicts caused by structures in the brain with different agendas, behavioral tendencies and phylogenetic origins… This view is consistent with Lashley’s provocative statement that ‘no activity of mind is ever conscious’ meaning that one is aware only of the products of cognitive processes, not of the processes themselves.

Consciousness in this theory is the way that those ‘products of cognitive processes’ can be melded together into single actions rather than competing ones. Although the predictive nature of consciousness is not mentioned by Morsella, it fits nicely with his theory.

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01/11/2009 by admin.

I keep an eye on the Less Wrong site because it often prods me into different ways of looking at things. Recently I ran across a reference there to a P. Watts post on paper by E. Morsella, ‘The Function of Phenomenal States: Supramodular Interaction Theory’. (here)

Morsella gives an interesting list of consciousness theories.

… contemporary findings in fields as diverse as cognitive psychology, social psychology, and neuropsychology have demonstrated that, contrary to what our subjective experience leads us to believe, many of our complex behaviors and mental processes can occur without the guidance of phenomenal processing. That is, they can occur automatically, determined by causes far removed from our awareness. … It seems that the processes that once served as the sin qua non of choice and free will – goal pursuit, judgment, and social behavior – can occur without conscious processes, raising again the thorny question, What is consciousness for?…

Regarding the function of these states, many hypotheses and conjectures have been offered. For example, Block (1995) claimed that consciousness serves a rational and non-reflexive role, guiding action in a non-guessing manner; and Baars (1988,2002)has pioneered the ambitious conscious access model, in which phenomenal states integrate distributed neural processes. Others have stated that phenomenal states play a role in voluntary behavior (Shepherd 1994), language (Banks 1995, Carlson 1994, Macphail 1998), theory of mind (Stuss & Anderson 2004), the formation of self (Greenwald & Pratkanis 1984), cognitive homeostasis ( Damasio 1999), the assessment and monitoring of mental functions (Reisberg 2001), semantic processing (Kouider & Dupoux 2004), the meaningful interpretation of situations (Roser & Gazzaniga 2004), and simulations of behaviour and perception (Hesslow 2002).

A recurring idea in recent theories is that phenomenal states somehow integrate neural activities and information-processing structures that would otherwise be independent…This notion, here referred to as the integration consensus, has now resurfaced in diverse areas of research… Many of these theories speak of a central information exchange, where dominant information is distributed globally…regarding the integration consensus, a critical issue remaining pertains to which kinds of dissemination require phenomenal states and which kinds do not.

Morsella’s theory is an elaboration of integration theories. Why and under what circumstances is integration required?

…the difference between the two kinds of processes (conscious and unconscious) cannot simply be one of controllability, for reflexes are controlled, sometimes in highly sophisticated and dynamic ways. In addition, the difference cannot simply be one of complexity because reflexive processes can be highly complex but unconscious…Faced with these difficulties, perhaps it is then fair to conclude that conscious processes, unlike reflexes, are consciously controlled, but this obviously provides nothing more than a circular explanation for why the two kinds of processes are different.

… I propose that the difference between conscious and unconscious processes lies in the kinds of information that have to be taken into account in order to produce adaptive behavior. Whenever the most adaptive response entails considering certain different kinds of information, phenomenal states are called into play….I review the task demands of some representative conscious and unconscious conflicts…

More on his theory next post.

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