03/09/2010 by admin.

What use is philosophy to science, or science to it? Paul Thagard thinks they have something important to offer one another, especially in the field of cognitive science. What philosophy offers science is a perspective on questions of theory, explanation and evaluation that allow scientists to think about these areas rather than just carry into their work implicit, unexamined, old philosophical notions. What science offers philosophy is a constraint on the possible theories that can be defended. Here is the abstract of a 09 paper (pdf here).

Contrary to common views that philosophy is extraneous to cognitive science, this paper argues that philosophy has a crucial role to play in cognitive science with respect to generality and normativity. General questions include the nature of theories and explanations, the role of computer simulation in cognitive theorizing, and the relations among the different fields of cognitive science. Normative questions include whether human thinking should be Bayesian, whether decision making should maximize expected utility, and how norms should be established. These kinds of general and normative questions make philosophical reflection an important part of progress in cognitive science. Philosophy operates best, however, not with a priori reasoning or conceptual analysis, but rather with empirically informed reflection on a wide range of findings in cognitive science.

Cognitive science is interdisciplinary – a collaboration in their areas of overlap of Philosophy, Linguistics, Anthropology, Neuroscience, Artificial Intelligence and Psychology according to Thagard. The disciplines have their own historical notions of what a theory looks like, and an explanation or evaluation. They deal with different levels of hierarchy from social to molecular. This is not unusual. Biology, itself, spans the hierarchy from the ecosystem to the molecular. Each biological science has its own theories, methods and ways of thinking but each does try to fit comfortable between the levels below and above their own. Physics has layers in harmony from particles to the cosmos. Cognitive science has not yet found that comfort.

My aim in this paper is to show that philosophy is essential to the interdisciplinary study of mind, but not for the reasons that many philosophers assume. Philosophy does not provide foundations for cognitive science and is incapable of generating the a priori truths that many philosophers have sought. Philosophy is not the queen of the sciences. Nor does philosophy have a special role in clearing up conceptual confusions about the study of mind, as this alleged role misunderstands the nature of concepts.

Along with many interesting ways he feels philosophy can be of use to cognitive science, he looks at the causal relations relations as they appear to various players.

A. reductionist: molecular - explains neural - explains psychological - explains social

Reductive reasoning is the normal sort of scientific explanation in other areas of science but has become a no-no in some cognitive science circles. Thagard is generous to those that bad-mouth reductionism but I wonder if a scholarly enterprise that does not accept a reductionist approach can be called a science.

B. downward: social – explains psychological, but neural and molecular are ignored

This is basically an anti-science approach and holds that the study of cognition is not concerned with the working of the brain. Perhaps it is an extreme post-modern stance.

C. autonomy: social, psychological, neural and molecular are three independent explanations

This is completely non-reductionist. Thagard believes it is motivated by two things: an attempt to protect psychology from encroachment, and making cognition more general for robotics and AI.

D. interactive: molecular – explains neural – explains psychological – explains social – explains molecular in a circle.

Thagard does not want to call this reductionist although it would certainly be recognized as home to most reductionists. It may be that it is necessary for him to not label himself with the taboo name.

He is very even handed but I am afraid that I am not so generous, no doubt because of recent conversations with a artificial intelligence person and on the other hand someone with a postmodern outlook. I was becoming very puzzled by how two people who professed to be extremely interested in thinking, cognition and mind, had no interest in neurobiology. If we are to understand thought and consciousness then it will be through science, Neurobiology especially.

Posted in Uncategorized | 1 Comment »

02/09/2010 by admin.

PLoS One has a paper, A Conserved Behavioral State Barrier Impedes Transitions between Anesthetic-Induced Unconsciousness and Wakefulness: Evidence for Neural Inertia, by Friedman and others here.

The abstract:

One major unanswered question in neuroscience is how the brain transitions between conscious and unconscious states. General anesthetics offer a controllable means to study these transitions. Induction of anesthesia is commonly attributed to drug-induced global modulation of neuronal function, while emergence from anesthesia has been thought to occur passively, paralleling elimination of the anesthetic from its sites in the central nervous system (CNS). If this were true, then CNS anesthetic concentrations on induction and emergence would be indistinguishable. By generating anesthetic dose-response data in both insects and mammals, we demonstrate that the forward and reverse paths through which anesthetic-induced unconsciousness arises and dissipates are not identical. Instead they exhibit hysteresis that is not fully explained by pharmacokinetics as previously thought. Single gene mutations that affect sleep-wake states are shown to collapse or widen anesthetic hysteresis without obvious confounding effects on volatile anesthetic uptake, distribution, or metabolism. We propose a fundamental and biologically conserved concept of neural inertia, a tendency of the CNS to resist behavioral state transitions between conscious and unconscious states. We demonstrate that such a barrier separates wakeful and anesthetized states for multiple anesthetics in both flies and mice, and argue that it contributes to the hysteresis observed when the brain transitions between conscious and unconscious states.

There are a number of pointers in this paper to the nature of consciousness. First is the indication that consciousness is not restricted to humans, or primates, or mammals or even vertebrates. Some of the molecular machinery involved in losing and gaining consciousness probably pre-dated the split between our line and that of the fruit fly. Consciousness, at some level, is likely very old and very general in animals.

Second, the hysteresis between being conscious and being unconscious may be functional. The brain is protected from small fluctuations in the system that might cause repeated fluctuations between consciousness and unconsciousness so that both are relatively stable states. The brain appears to be almost bistable with a fairly clean transition between the two states.

Third, the fall into unconsciousness is quicker (steeper) than the re-establishment of consciousness. This may indicate that consciousness is easier to disrupt than to initiate; it is a more complex state.

This work was done with anesthetics on animals and therefore cannot be applied directly to the sleep-wake cycle in humans. There are parallels though between hysteresis in anesthesia in mice and sleep inertia in humans. It is really hard to wake up, even if it is not Monday!

Friedman EB, Sun Y, Moore JT, Hung H-T, Meng QC, et al. (2010). A Conserved Behavioral State Barrier Impedes Transitions between Anesthetic-Induced Unconsciousness and Wakefulness: Evidence for Neural Inertia.
PLoS ONE 5(7) DOI: 10.1371/journal.pone.0011903

Posted in Uncategorized | 1 Comment »

01/09/2010 by admin.

There is a posting in MIT Technology Review (here) about an electronic device called a memristor. It acts like a resister with a memory and was first produced about a year ago.

…it turns out that the synapses between neurons behave exactly like memristors. That raises the possibility that memristors can be connected together in a way that truly mimics the wiring of human brains.

One of the defining features of the connections between neurons is that they become stronger when neurons fire together; hence the phrase “neurons that fire together, wire together”, a phenomenon otherwise known as Hebbian learning. Various experiments have shown that this effect is most pronounced early in the learning process, when the increase in connection strength is greatest. Later learning merely reinforces the links

(there have been problems with memristor curcuits) Merrikh-Bayat and Bagheri have a simple solution: use two memristors in series. Choosing their memristance carefully allows them to reproduce Hebbian-type synapse strengthening more or less exactly.

That may turn out to be a useful insight. The first neuromorphic chips to use memristance to mimic synapse behaviour are already being built. A small change in their design may make a significant difference.

This is gives an approximation of a neuron for research but still is a long way from actual neurons. I think an electronic neuron may have to react to electrical and magnetic fields and also to many chemical gradients (or have a way to simultate these) before it can mimic a real neuron’s actual behaviour.

Posted in Uncategorized | 1 Comment »

28/08/2010 by admin.

Humans are social animals. What does it mean to be social? A great many things, I am sure, would be put forward to answer that question and most would be accurate. I am intrigued by how we manage to coordinate: coordinate to communicate, coordinate in joint actions, coordinate to align goals. I cannot imagine social life without coordination between people.

Recently there was a report in the Scientific American on work by Uri Hasson. He showed a coupling between brain activity in a speaker and listener but only when there was verbal understanding. This work used fMRI, so it was difficult to arrange a real conversation against the noise and isolation of the equipment. We seems to be able to steer one another’s brain activity. Previous blog is communication between brains.

Now, in PloS is a different take on how brains coordinating, a paper by Dumas, Nagel, Soussignan, Martinerie and Garners, Inter-Brain Synchronization during Social Interaction (here). In this case the behaviour that was being aligned was meaningless hand movements. Subjects could create their own movements, mimic each other or not, synchronize their movements or not, and control taking turns while their EEGs and behaviour were recorded. Here is the abstract:

During social interaction, both participants are continuously active, each modifying their own actions in response to the continuously changing actions of the partner. This continuous mutual adaptation results in interactional synchrony to which both members contribute. Freely exchanging the role of imitator and model is a well-framed example of interactional synchrony resulting from a mutual behavioral negotiation. How the participants’ brain activity underlies this process is currently a question that hyperscanning recordings allow us to explore. In particular, it remains largely unknown to what extent oscillatory synchronization could emerge between two brains during social interaction. To explore this issue, 18 participants paired as 9 dyads were recorded with dual-video and dual-EEG setups while they were engaged in spontaneous imitation of hand movements. We measured interactional synchrony and the turn-taking between model and imitator. We discovered by the use of nonlinear techniques that states of interactional synchrony correlate with the emergence of an interbrain synchronizing network in the alpha-mu band between the right centroparietal regions. These regions have been suggested to play a pivotal role in social interaction. Here, they acted symmetrically as key functional hubs in the interindividual brainweb. Additionally, neural synchronization became asymmetrical in the higher frequency bands possibly reflecting a top-down modulation of the roles of model and imitator in the ongoing interaction.

It is fairly clear that synchronized activity in the brain is important to the nature of thought. Different rhythms are involved in different activities. Hebb’s famous quote, “cells that fire together, wire together”could also be, “cells that fire together, give us consciousness”. Or it could be enlarged in scope to “brains that fire together, communicate.”

we were able to show that the alpha-mu rhythm was the most robust interbrain oscillatory activity discriminating behavioral synchrony vs. non synchrony in the centroparietal regions of the two interacting partners. The alpha-mu band is considered as a neural correlate of the mirror neuron system functioning. Specific frequencies of this band (9.2–11.5 Hz) over the right centroparietal region have been proposed as a neuromarker of social coordination.

This work and, I hope, future research along these lines are very important steps towards understanding our social nature.

Citation: Dumas G, Nadel J, Soussignan R, Martinerie J, Garnero L (2010) Inter-Brain Synchronization during Social Interaction. PLoS ONE 5(8): e12166. doi:10.1371/journal.pone.0012166

Posted in Uncategorized | 1 Comment »

25/08/2010 by admin.

There is a new project (like the human genome project) called the human connectome project to which the NIH has given $30 million. The hope is to map the connections in the whole human nervous system. Some new experimental procedures seem to make this possible although it will take an enormous amount of work. It also needs the sort of powerful computer systems that now exist to build the map and make it usable – the amount of data with be enormous.

Only some corners have been mapped so far. The indications from these starts are that the brain is organized more like a flat network and less like a hierarchy. This is in line with recent thinking and moving away from top-down/bottom-up thinking. There seems to be no top and no bottom. Also being confirmed is the notions of loops and circuits, structures involved in feedback.

When I was young, the brain is envisaged as a telephone exchange, then as a computer, but now the analogy is with the internet. The idea is that there are a large number of ways to get from any one neuron to another and back again. We are now seeing the first experimental evidence for this new way of seeing the brain.

The basic connections are made during the development of the nervous system. There is a complicated dance of migrating cells forming layers, sheets, grids and knots. Mistakes in this process cause some very serious conditions. Then, with the person born into and living in the real world, this structure of connections is tailored in each individual. Connections are lost and gained to fit a particular person’s age, history, surroundings, culture, language and so on. The original basic architecture is not lost in this tailoring and learning process. Useful links are strengthened and useless ones weakened or lost, but the structure remains.

We can assume that there will be surprises along the way to this map just as there were with the human genome project. Perhaps we will be able to see the architecture of consciousness in a few years.

Posted in Uncategorized | 1 Comment »

22/08/2010 by admin.

A paper in Nature Neuroscience, ‘Predicting visual stimuli on the basis of activity in auditory cortices’, by Meyer, Kaplan, Essex, Webber, Damasio, Damasio, gives a picture of the role of the earliest sensory cortex in conscious experience. If a perception is in consciousness then it can be found in the ealy sensory cortex even if it is not part of the current sensory input.

Using multivariate pattern analysis of functional magnetic resonance imaging data, we found that the subjective experience of sound, in the absence of auditory stimulation, was associated with content-specific activity in early auditory cortices in humans. As subjects viewed sound-implying, but silent, visual stimuli, activity in auditory cortex differentiated among sounds related to various animals, musical instruments and objects. These results support the idea that early sensory cortex activity reflects perceptual experience, rather than sensory stimulation alone.

They discuss the evidence that this also happens in sight and touch.

There is growing evidence for an involvement of early sensory cortices in the conscious experience of sight and touch. For example, in perceptual illusions, activity in primary visual and somatosensory cortices has been shown to correspond more closely to the subjects’ visual or haptic experience than to the physical properties of the stimuli presented. Furthermore, when subjects imagine visual objects in the complete absence of perceptual input, primary visual cortices are activated and appear to specifically represent the contents of the subjects’ visual experience. Activity in primary visual cortices has also been shown to correlate with stimuli that are kept active in working memory. Although previous studies have established that early auditory cortices can be activated during auditory imagery, auditory hallucinations and the perception of implied sound, the content specificity of such activations has not yet been demonstrated. Our findings suggest that, just as in the visual and somatosensory modalities, activity at the earliest stages of cortical auditory processing correlates specifically with the experience of sound reported by the subjects, rather than with the actual auditory environment alone, as the latter was entirely silent during the presentation of the video clips.

So does this mean that we are closer to qualia? No matter why a sight, touch or sound is in consciousness (current perception, imagining, memory, hallucination) its footprint is found in the early sensory cortex where we would expect only signals just starting their perceptual journey.

Posted in Uncategorized | 1 Comment »

19/08/2010 by admin.

A few months ago there was an article by T. Sejnowski in the Scientific American Mind Matters (here). The question was how long it will take to be able to build a brain resembling our own brains. He talked about the two front runners, who differ in their approach but have the same time estimate, about a decade for the first reverse-engineered brains.

The backdrop for the debate is one of dramatic progress. Neuroscientists are disassembling brains into their component parts, down to the last molecule, and trying to understand how they work from the bottom up. Researchers are racing to work out the wiring diagrams of big brains, starting with mice, cats and eventually humans, a new field called connectomics. New techniques are making it possible to record from many neurons simultaneously, and to selectively stimulate or silence specific neurons. There is an excitement in the air and a sense that we are beginning to understand how the brain works at the circuit level. Brain modelers have so far been limited to modeling small networks with only a few thousand neurons, but this is rapidly changing.

There is a dispute between Dharmendra Modha of IBM and Henry Markram of the Ecole Polytechnique Federale de Lausanne Blue Project. The two groups are the front runners but differ in philosophy.

Both groups are simulating a large number of model neurons and connections between them. Both models run much, much slower than real time. The neurons in Modha’s model only have a soma — the cell body containing the cell nucleus — and simplified spikes. In contrast, Markram’s model has detailed reconstructions of neurons, with complex systems of branching connections called dendrites and even a full range of gating and communication mechanisms such as ion channels. The synapses and connections between the neurons in Modha’s model are simplified compared to the detailed biophysical synapses in Markram’s model. These two models are at the extremes of simplicity and complex realism.

This controversy puts into perspective a tension between wanting to use simplified models of neurons, in order to run simulations faster, versus including the biological details of neurons in order to understand them. Looking at the same neuron, physicists and engineers tend to see the simplicity whereas biologists tend to see the complexity. The problem with simplified models is that they may be throwing away the baby with the bathwater. The problem with biophysical models is that the number of details is nearly infinite and much of it is unknown. How much brain function is lost by using simplified neurons and circuits?

I think it will take both types of simulation to understand consciousness and it will need simulation of the mid-brain as well as the cortex and the rest of the fore-brain. The hind-brain may even need to be included.

Addition - Reverse engineering rebuttal

It seems that at present there is a discussion about expecting reverse engineering of the brain in a decade. Ray Kurzweil who is a predictor of the future gave a speech at the Singularity Summit predicting that the brain would be reverse engineered in about 10 years. PZ Meyers in Pharyngula has attached Kurzweil’s logic. (here) Meyers is right in my opinion about the ignorance of biology on the part of Kurzweil – He seems to be in some other world and not worth listening to. However, Meyers himself shows his doubt about when reverse engineering will produce results. He feels 10 years is just wrong. Markram and Modha who are attempting it by different methods both hope to be somewhere significant in 10 years. They are not making foolish assumptions like Kurzweil. They are not starting with the genetic code etc. but with studies of architecture and the behavior of ion channels and the like. Meyers remarks do not touch their efforts as far as I can see.

Posted in Uncategorized | 1 Comment »

01/08/2010 by admin.

The electrical signals traveling the along neurons create a surrounding electrical field which adds to the fields created by the activity of other neurons. The EEG trace is the result of these combined fields. Scientists have been attempting to obtain more and more information on the processes of the brain by studying these fields. But what about the opposite effect – do electrical fields affect the activity of neurons?

Scientific American has a article by F. Jabr (here) on research by D. McCormick showing that this is a feedback loop.

A few neurons are like individuals talking to each other and having small conversations. But when they all fire in unison, it’s like the roar of a crowd at a sports game… They surrounded the cortical sample with an electric field that approximated the size and polarity of the fields produced by an intact ferret brain during slow-wave sleep to create an exaggerated version of the exact feedback loop they were investigating. Essentially, they enveloped the brain slice in an echo of itself.
When the team applied this electric field echo, they found it amplified and synchronized the neural activity in the brain slice. The field didn’t create disorder—it increased harmony. The “roar” of the brain slice became louder and more regular. “It’s kind of like if you were cheering at a football game and someone played over the speaker the sound of the crowd cheering and you started responding to that, too, cheering along with both the real crowd and the speaker playback,” McCormick explains. “It’s a kind of reinforcing feedback.”
Not only did the researchers show that this positive feedback facilitated the synchronous slow waves of electrical activity in the slice of ferret brain, they also showed that an electric field of the same strength, but opposite polarity, disrupted its synchronous neural activity.

This is not a surprising result; it is to be expected that an electrical field would affect an electrical current. It also appears that the brain responds to magnetic fields and I presume also produces them. It is also clear that neuron activity is affected by various chemical gradients. This should put paid to the idea that the brain is digital. Many aspects of communication in the brain vary continuously (like an electrical field does) and everything is not ‘fire or don’t fire’ (like a digital computer’s 1 or 0 and nothing in between). Computers are a very, very limited analogy for biological brains.

Posted in Uncategorized | 1 Comment »

07/07/2010 by admin.

ScienceDaily has an item on research by M. Pessiglione investigating subliminal motivation. (here) In the experiment they gave the subject a subliminal look at the level of reward available for the strength of a hand squeeze. The size of reward affected the strength of the squeeze. In a second experiment the subliminal reward information was projected to only one eye (the therefore one hemisphere of the cortex) and the effect on the squeeze was only found for the one hand (controlled by the same hemisphere) and not the other.

The research shows that it’s possible for only one side of the brain, and thus one side of the body, to be motivated at a time, says Pessiglione. “It changes the conception we have about motivation. It’s a weird idea, that your left hand, for instance, could be more motivated than your right hand.” He says this basic research helps scientists understand how the two sides of the brain get along to drive our behavior.

The way I interpret this is that the size of the reward affects motivation. This is true even if the picture of the reward has too short a duration to reach consciousness. When the subliminal information is projected to only one side of the cortex, it remains only local knowledge. The other hemisphere would have knowledge of the reward only if it rose to consciousness and the short duration prevents this. Consciousness would seem to be very important for access and coordination between the two hemispheres at least in some situations.

Posted in Uncategorized | 1 Comment »

02/07/2010 by admin.

Our society has a problem with the dissemination of information about science. There are the scientific journals that are far, far to specialized for anyone outside that particular area of science to read and understand, even if they have a fairly good general education that included sciences. Then there are popular science books and articles written by scientists (and some good journalists) for the lay public. The problem with these is that they are too rare, far too rare. And finally there are articles and books written by people who are basically ignorant of the subject matter and are out to shock, titillate, entertain or discredit. Quite often these books/articles use dichotomies in a pretend conflict for effect. The rule appears to be ‘hang your article on a controversy’. An example is discussed by Ledoux (here). It is the left-brain verses right-brain fake dichotomy that has annoyed him.

Here are some pop science ideas that bother me. See any the these and you know that the author is either ignorant of the subject or cutting corners.

1. nurture verses nature: We cannot separate genetics for environment in any sort of useful quantitative way; they are too interwoven, interdependent and an multifaceted in their interactions. This is a political football and not a scientific question. Everything about you is controlled by genetics and, at the same time, everything about you is controlled by your environment – and this is not impossible. Genetics and environment are not in competition.

2. The gene for ‘x’: There is no gene for aggression, for mathematics, for autism etc. Genes control things like a type of cell migration which in turn (with other genes and environmental factors in the womb) produces the anatomical structure of the brain. That in turn, with other genes and environmental factors, gives tendencies toward ‘x’. How genetics works is not rocket science – it is more complicated than rocket science. We can have a gene for a particular enzyme because genes code for proteins, but not for disliking spinach.

3. Mind verses matter: Dualists are now very rare in philosophy and even rarer in neuroscience. Forget about some immaterial mind stuff. It is a dead as vitalism.

4. Brain verses body: The brain and the rest of the body are not separate systems. What is happening in the brain effects the body beyond just the muscles and glands. And what is happening in the body effects the brain beyond just the sense organs. The ‘embodied mind’ is pretty much accepted.

5. The reptilian brain/the primitive brain: We do not have some unchanged ancient part of our brain. We share some anatomy with all other vertebrates but none of it has remained unchanged by evolution. Various structures in the hind-, mid- and fore-brain work together although they arose in evolution over time with the hind- first and the fore-brain last. It is like saying that the heart is more primitive than the lungs because hearts are evolutionarily older. We do not have shark hearts or reptile brains.

6. Left brain verses right brain: The two hemispheres are connected and work together, very closely together. The only time you have a two brains is when the two hemispheres are surgically separated.

7. Conscious mind verses unconscious mind: This is the big one as far as this blog is concerned. We do not have two minds – we have one. Most of what the mind does is not in our awareness – we are unconscious of it. But some of what the mind does we are aware of – we are conscious of it. We have an unconscious mind and consciousness of some of the products of that mind (perception, cognition, intention etc.) To read some pop science you would think that the unconscious was some hidden evil trying to undermine our best efforts.

8. Freewill verses determinism: I think most neuroscientists do not accept either concept but instead envision a complex decision making and control process in the brain which is neither free or determined as those words are ordinarily used in this context. (But it is still a question for some philosophers.)

9. Humans verses other animals: This is sometimes said as, ‘humans are unique’. Doh! All species are unique. It is only natural that we are more interested in what makes us unique than what makes fruit bats unique. We share the basics with other animals. We share the forerunners of our most typical abilities with our closest animal relatives. There is no reason to think that other animals do not think, feel, communicate etc. even if we do these things much better then they do.

Posted in Uncategorized | 2 Comments »