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.

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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

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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.

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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

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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.

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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.

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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.

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16/08/2010 by admin.

Some avoid the word ‘communication’ because it is in some ways too vague and in others too specific. I like it because it does not make arbitrary boundaries between different modes of communication, reasons for engaging in it, or content. What is specific about communication is that it takes at least two to communicate; it is not about what is said, written, illustrated, singed, sang or whatever, nor about what is heard, read, seen and so on, it is about an exchange between two minds.

I regularly read a blog by E. Bolles called Babel’s Dawn (here). He reviews many books and articles on the origins of language but always comes back to his favourite idea, that there is a triangle of joint attention involving the speaker, listener and topic. Words pilot attention to topics, a bit like pointing a finger but more complex. I like this idea.

This fits with an idea that is a favourite of mine. I see a word as having no meaning by itself, its meaning is a result of its relationship to other words. There are a few words, proper names of places, people etc., that can take their meaning from actually pointing to something. Other words point to concepts and archetypes in the mind. And in turn, the concepts get their meaning from their connection with other concepts, a web of actual connections that by their relationships define their meanings. This is why we seem to rely on metaphor so heavily. If we have a group of entities (words, concepts, things) and they are joined by lines (relationships, actions) to form a structure that we know and understand, we can re-use that structure. As an example, we have place A, place B, moving from A to B, and the thing moving so that the structure is a journey. This can be elaborated with the reason/goal of the move, the path, events along the way, and other elements/relationships. A can be thought of as the start and B as the destination. We can re-use the metaphor for a hike, a drive, a train journey, a boat ride and every different use adds depth and complexity to the metaphor. Now if I want to steer joint attention to the end point of a plan, I can say, ‘think about our goal and how close we have come to it’. We can go further and use the structure for non-journey ideas: a career, a life, a task and so on. Using words to pilot joint attention only works because we share a large number of elaborate metaphors. We learn our language/s and our culture’s metaphors and meaning structures and because we share these with others, we can (almost literally) point to something in someone else’s mind. This is an amassing thing – instead of using my finger to point to a tree in the yard, I can use a word to point at a tree concept in your head.

Another idea that I find interesting is the synchronization of two people in communication. We do not wait until someone stops speaking to parse the meaning of what they have said. In really successful communication, we start timing our own thinking to be in the same timing pattern as the speaker. We predict what the other is going to say ahead of hearing it. We take in their whole person to understand what they are saying: voice, face, posture, movement as well as words. We do not communicate in just words but with our whole selves. Apparently this synchronization, prediction and shared concepts can be vaguely by made out in fMRI scans and these patterns break down as soon as the two people lose understanding of what the other is saying. We are actually able to share a joint attention to a topic that is a concept in our brains.

There is a question often raised – does our language reflect the nature of our thoughts, or does thought reflect the nature of our languages? I cannot think of this question in any other way than the structure and processes of the brain dictate the general form of language (joint attention, metaphor, synchrony and so on). But the shared culture is what makes communication work. We have to want to communicate, we have to share a language and very large numbers of metaphors before it clicks. Sharing a culture has a large effect on what we think (but not how we go about the thinking).

So now back to the topic of this blog. It seems that we communicate with ourselves as well as others and we do at least a fair amount of this internal communication through consciousness. The production of speech is not conscious, the perception of speech is not conscious. We have no feeling for how either of these things is done – it is opaque. But the meaning, the high level representation of the voice and words are usually made conscious. This may be because the formation of a grammatical utterance is quite complicated so that working memory is required to hold parts of the stream while other parts are prepared or processed. Anything that needs working memory is extremely likely to be made conscious and transferred to short-term memory. I cannot see how most speech could be produced or understood without making use of working memory. Short-term memory would also be needed for any utterance longer than a simple sentence or phrase; for a conversation we need to know what went before.

I assume that many (maybe most) animals have concepts, communication, working memory and consciousness. But over the last few hundred thousand years, humans have fashioned from these common attributes, the marvel of verbal communication. Again Babel’s Dawn has a constant idea that the reason language was acquired by humans and not other animals is in the nature of our societies. Put quite simply, we have come to have trust in sharing information with our fellows. Playing with language is as dangerous as playing with fire or wolves, but the gains are just as great, probably greater.

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13/08/2010 by admin.

In the spring, Neurophilosophy had a post on the research of D. Havas into the effects of botox on emotion. (here).

Do you smile because you’re happy, or are you happy because you are smiling? Darwin believed that facial expressions are indeed important for experiencing emotions…Botox, which is used by millions of people every year to reduce wrinkles and frown lines on the forehead, works by paralyzing the muscles involved in producing facial expressions…it impairs the ability to process the emotional content of language, and may diminish the quality of emotional experiences…

Havas recruited 40 women for the new study, all of whom were seeking first-time botox injections as a cosmetic treatment for frown lines on the forehead. These participants were asked to read sentences describing happy, sad or emotionally neutral situations. Immediately afterwards, they were taken to the physician, who gave them a single injection of botox into the corrugator supercilii, or “frown” muscle. (Botox acts by inhibiting the release of the neurotransmitter acetylcholine from motor neurons, leading to temporary muscle paralysis 24-48 hours later. Typically, the procedure is repeated after 3-4 months; with time, the muscles may atrophy, or waste away, through disuse.) Two weeks after the injection, the participants returned to lab to read another set of similar sentences.

The reseachers found that botox slowed the reading of the sentences containing sad emotional content, which, as the earlier work showed, would normally cause the frown muscle to contract. The reading time for the happy and neutral sentence was the same in both sessions. The researchers assume that the increase in reading time means that paralysis of the frown muscles hindered the participants’ understanding of the emotional content of the sad sentences. They also argue that their findings support the hypothesis that feedback from the muscles involved in producing facial expressions is critical in regulating emotional experiences.

…news stories completely overlook the more profound implication of the results - that by paralyzing the muscles involved in producing facial expressions, botox may actually diminish the experience of emotion in those who use it.

This is another piece of evidence that consciousness is primarily concerned by perception. In this case it is registering an emotional state primarily from the perception of movement of facial muscles.

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10/08/2010 by admin.

Science Daily has a report on investigation of animal sense of direction. (here) R. Langston found that baby rats have a space map before they can see or navigate outside the nest.

The research team implanted miniature sensors in rat pups before their eyes had opened (and thus before they were mobile). That enabled the researchers to record neural activity when the rat pups left the nest for the first time to explore a new environment.

The researchers were not only able to see that the rats had working navigational neurons right from the beginning, but they were also able to see the order in which the cells matured.

The first to mature were head direction cells. These neurons are exactly what they sound like — they tell the animal which direction it is heading, and are thought to enable an internal inertia-based navigation system, like a compass. “These cells were almost adult-like right from the beginning,” Langston says.

The next cells to mature were the place cells, which are found in the hippocampus. These cells represent a specific place in the environment, and in addition provide contextual information — perhaps even a memory — that might be associated with the place. Last to mature were grid cells, which provide the brain with a geometric coordinate system that enables the animal to figure out exactly where it is in space and how far it has travelled. Grid cells essentially anchor the other cell types to the outside world so that the animal can reliably reproduce the mental map that was made last time it was there.

It has been assumed by many, for a long time that our 3D space perception is hard-wired and not gained from experience of space. This and similar research seems to confirm that assumption.

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