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Archive for December, 2005

Blog introspections

At the end of this month and year, our stats are indeed looking promising. We have only started to gather statistics from 11. December, and we have already had a good amount of visits. Close to 600 in all in about 20 days — and doing so without any deliberate ads anywhere (well, except a note at my group, Mind & Brain at yahoogroups).

There are two primary motivations behind this blog. The first is that it serves as an archive for out research on neuroethics, on the road of making a book about it. The book will be written in Danish, but it of course our hope that it can be translated into other languages, e.g. English. So in terms of the book project, we needed somewhere to arhive our items. In extension to this, we also thought a blog would be good for more free thoughts and views in the preparation of the book.

But why should we hold this archive just for ourselves? Why not share this with others? I think the answer is obvious – brain science produces a hole new range of findings that goes straight to the bone of what it actually means to be human. In order to understand these new findings and their implications, there must be a bridge between the researchers and the public (and the media). Martin and I are both cognitive neuroscientists, having our hands in the mud, so to speak. Why let others think about the consequences of what we are doing? Why not discuss this ourselves — share our thoughts, concerns and visions? In addition, since there is an abundance of brain-hype sites and news, we hope to bring up to date, balanced news and views following the proper scientific rigor!

So while much of what we write is to our own amusement and preparation, we hope that you will be amused with us. And please drop in for comments and discussions. We’d love to hear your opinions.

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Every year the American Modern Language Association stages a conference where English professors and students from all over the US gather to discuss the state of literary criticism and theory. Think Society for Neuroscience, if you need a comparison.

This year, as Nick Gillespie tells us in this report, the talk focused on cognitive approaches to the study of literature. The old paradigm – postmodernism or whatever you would like to call it – seems to be in decline. Will a cognitive approach be the next big thing?

Well, since literary texts are composed of string of words, and since it takes the processing of neurocognitive mechanisms to make sense of such strings of words, we should certainly hope so! Still, personally I wouldn’t hold my breath. It is, though, heartening to see that a few valiant cognitivists are trying to break the anti-biological spell of modern lit-crit.

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The structure of today is the anterior cingulate cortex (ACC). Two new studies jointly illuminate the function played by this intriguing part of the brain. In many imaging studies the ACC lights up in connection with cognitive processing, especially when something goes wrong. Some researchers have speculated that the ACC may work as a cognitive error-detection device. Other studies implicate the ACC in emotional processing (and, traditionally, the ACC has been grouped anatomically as part of the limbic system). So, what is it, cognition or emotion?

In a forthcoming paper in Brain and Cognition, Ray Dolan, Hugo Critchley and their colleagues at FIL in London test two patients with damage to the medial part of the prefrontal cortex (including ACC) on a number of cognitive tasks. They conclude (citing the abstract) that

both patients showed intact intellectual, memory, and language abilities. No clear-cut abnormalities were noted in visuoperceptual functions. Speed of information processing was mildly reduced only in Patient 2 (bilateral ACC lesion). The patients demonstrated weak or impaired performance only on selective executive function tests. Performance on anterior attention tasks was satisfactory.

This suggests, they say, that

our findings are inconsistent with anterior attention theories of ACC function based on neuroimaging findings. We propose that the data may imply that the ACC does not have a central role in cognition. We speculate that our findings may be compatible with the view that the ACC integrates cognitive processing with autonomic functioning to guide behaviour.

As it so happens, another new study by scientists at Stanford and Harvard, reported two weeks ago in PNAS, backs up this conclusion. In this study, subjects used real-time fMRI to modulate feelings of pain by learning to control activity in the rostal part of the ACC. This finding is really quite astonishing, I think! As the authors remark in the abstract to their paper

When subjects deliberately induced increases or decreases in rACC fMRI activation, there was a corresponding change in the perception of pain caused by an applied noxious thermal stimulus. Control experiments demonstrated that this effect was not observed after similar training conducted without rtfMRI information, or using rtfMRI information derived from a different brain region, or sham rtfMRI information derived previously from a different subject. Chronic pain patients were also trained to control activation in rACC and reported decreases in the ongoing level of chronic pain after training. These findings show that individuals can gain voluntary control over activation in a specific brain region given appropriate training, that voluntary control over activation in rACC leads to control over pain perception, and that these effects were powerful enough to impact severe, chronic clinical pain.

The over-all conclusion, thus, appears to be that the ACC do have something to do with the control of behaviour, but mostly with emotional behaviour. Why does it then pop up in so many imaging experiments on cognition? One possible answer could be that the ACC is the neurocognitive seat for integrating emotional responses to some activity or perception with the sequencing of cognitive behaviour. Further research will hopefully tell.

References

Baird, A. et al. (in press): Cognitive functioning after medial frontal lobe damage including the anterior cingulate cortex: A preliminary investigation. To appear in Brain and Cognition.

deCharms, R.C. et al. (2005): Control over brain activation and pain learned by using real-time functional MRI. PNAS 102: 18626-18631.

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The most fascinating scientific result of 2005 – to my mind, at least! – was the sequencing of the chimpanzee genome, reported in the September 1 issue of Nature. (Remember also to read the many accompanying articles on chimp research in the same issue.) Although not the first genome to be sequenced, the chimp genome holds a special importance to research on human cognition and behaviour. The reason for this is the well known fact that chimpanzees are our closest primate relatives. Some 5 to 7 million years ago chimps and the human lineage shared a common ancestor. A comparison of the chimp genome with the human genome will therefore provide invaluable insights into the evolutionary process leading to the creation of homo sapiens. Some interesting finds have already been made. As Elizabeth Culotta and Elisabeth Pennisi write in the Science “breakthrough of year” article that Thomas mentions below

we differ by only about 1% in the nucleotide bases that can be aligned between our two species, and the average protein differs by less than two amino acids. But a surprisingly large chunk of noncoding material is either inserted or deleted in the chimp as compared to the human, bringing the total difference in DNA between our two species to about 4%.

This circumstance feeds a growing suspicion that humans do not so much differ from chimps because of new genes being expressed as because the old genes we share with our chimpanzee brothers and sisters are expressed in a different manner. Various techniques for comparing primate brains (cytoarchitectonics, stereology, imaging) tell much the same story. The human brain is not essentially different from the chimp brain: anatomical areas are more or less arranged in the same manner, it is composed of basically the same cells, and many of the functions it performs are, grosso modo, similar to the functions performed by the chimpanzee brain. There are differences, to be sure. The gene FOXP2, for instance, have mutated twice since the human lineage separated from the chimp lineage. The expression of FOXP2, a trancription factor, is compromised in an English family with a severe speech impediment. Thus, the new variant of foxp2 may have played a role in bringing about human language. Also, Katerina Semendeferi has shown that Brodmann area 10, at the frontal pole of brain, is larger in humans relative to the rest of the brain. Its supragranular layers also appear to form more densely connections with other association areas in the human brain. Yet, it is impossible to say that humans differ from chimps on this or that behaviour which is the product of some new patch of cell tissue, only present in the human brain. We seem to come equipped with a “chimpanzee” brain that have just been modified in a number of subtle ways. Understanding how constitutes one of the great challenges of contemporary science.

On the face of it, chimp behaviour appears to be very different from human behaviour. There are no chimpanzee artists or scientists, for example. No skyscrapers or bridges have been build by chimpanzee engineers and architects. No chimpanzee is blogging from the rainforest of Tanzania about what Jane Goodall is up to these days! For the past 50 years researchers have assembled a long list of putative cognitive cognitive abilities that are unique to humans, and hence contribute to making us different from other primates. However, years of careful observation, and numerous experiments, have, item for item, dismantled this list. Sure, only humans speak, but apes clearly have some semantic capability and are able to refer symbolically to these mental concepts. No chimp will put more than two entities together to form a tool, but they do use sticks to fish for termites, or stones to crack open nuts. Until very recently, most primatologists concurred that only humans are able to read other conspecifics’s minds – that is, that we are the only species to be imbued with a Theory of Mind. It turns out that this is not true. Chimps have ToM as well! Again, tool use, language, and mentalizing, are all clearly different in humans, but they can’t be said to be altogether absent from chimps, if you look carefully at the underlying neurocognitive mechanisms. The lesson to be gained from these behavioural studies, once more, seems to be that humans have inherited a more basic capacity from our common chimp-human ancestor and then have run with it.

A case in point is culture. Culture is very much something we associate with humans, and something that from time to time has appeared on the “unique capacities” list. The “human sciences”, to a large degree, simply define their object of inquiry as culture. (In German the human sciences are often referred to as Kulturwissenschaft; in the US much work go under the name “cultural studies”.) In 1999, however, 9 of the world’s leading primatologists published a report in Nature where they documented that chimps at 7 African communities have developed cultural differences in the use of tool, or social behaviour. The authors define a cultural tradition as behaviour patterns that are customary or habitual in one community, but absent in others, but which cannot be explained by ecological differences. In a recent review of this research, also published in Nature, one of the authors, Andrew Whiten, note that number of cultural traditions observed in chimpanzee communities greatly exceeds those found in other species. In fact, other mammals, fish and birds commonly only have been associated with just one tradition. 19 have been identified in orangutans. But a repertoire of no less than 40 behavioural variants have been observed in chimp communities, so something appear to have changed throughout primate evolution. The critical question of course being: what?

Does such behavioural traditions really amount to the thing we call human culture? Well, we may point to some obvious differences: there are a lot more than 40 traditions around in human communities; human culture is cumulative (i.e., we build on, and sometimes improve upon, other people’s behaviour); and many thinkers would argue that human culture is just a much about values as about behaviour. Still, the formation and transmission of traditions are without doubt part and parcel of human culture as well. Perhaps the real benefit from comparing chimp and human culture will be an improved notion of what just exactly culture is! (Such as this attempt by Richard Byrne and colleagues amply show.)

Now, what could possibly be the neurocognitive mechanisms underlying the primate ability to form and transmit cultural traditions? Stay tuned for part II!

To be continued…

Byrne, R. et al. (2005): Understanding culture across species. Trends in Cognitive Science 8: 341-346.

Chimpanzee Sequencing and Analysis Consortium (2005): Initial sequence of the chimpanzee genome and comparison of with the human genome. Nature 437: 69-87.

Whiten, A. et al. (1999): Cultures in chimpanzees. Nature 399: 682-685.

Whiten, A. (2005): The second inheritance system of chimpanzees and humans. Nature 437: 52-55.

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An article on Giulio Tononi‘s work on the brain basis of consciousness has just been published in Science & Consciousness Review. Henri Montandon reviews some of the recent publications by Tononi. Excerpt from the article:

“Tononi’s writings are noteworthy for his grounding in phenomenology, and his lucid style of presentation. He has noticed three aspects of conscious experience:

  1. given any definition of “conscious state”, the brain produces an infinity of them;
  2. each conscious state is prime, rather in the sense of a prime number; it cannot be deconvoluted into lesser states. Tononi terms this characteristic the “integration” of a state;
  3. conscious experience unfolds in well defined intervals, about 100 to 200 milliseconds to develop a fully formed sensory experience, about 2 to 3 seconds for a single conscious moment.

It is these three observations which Tononi seeks to understand in his information integration theory of consciousness. He discusses two hypotheses:

  1. consciousness corresponds to the capacity of a system to integrate information
  2. the quality of consciousness is determined by the informational elements of a complex, which are specified by the values of effective information among them.”

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Yes, every seventh second a new case of dementia develops in the world. Medscape.com reports this from a just published report in The Lancet. Such a number pinpoints the necessity of finding viable solutions to fight degenerative brain disorders. Such an effort must work on many levels; devising new and improved methods for detecting dementia as early as possible; slowing the progression of the disease; finding treatments that halt or even repair neural damage; improving the healthcare of patients suffering from dementing disorders. Approaches are numerous, but we still know little about the mechanisms behind each type of dementia – and there are more than 100 known causes!

With increasing mean age across the world, and with the proportion of elderly growing in the coming years, much effort should be put into the research into neurodegenerative disorders.

From medscape.com

Globally, New Dementia Case Arises Every 7 Seconds

NEW YORK (Reuters Health) Dec 16 – Findings from a review of published studies suggest that every 7 seconds a new case of dementia occurs somewhere in the world.

“We believe that the detailed estimates in this paper constitute the best currently available basis for policymaking, planning, and allocation of health and welfare resources,” lead author Dr. Cleusa P. Ferri, from King’s College London, and colleagues note.

The researchers used the Delphi consensus method to estimate the global prevalence of dementia. With this method, quantitative estimates are derived through the qualitative assessment of evidence, according to the report in the December 17/24/31st issue of The Lancet. In the present study, 12 international experts used data from published studies to estimate the prevalence of dementia in every World Health Organization world region.

Roughly 24.3 million people currently have dementia and 4.6 million new cases arise every year, the authors state.

A doubling of the prevalence will occur every 20 years, so that by 2040, about 81 million people will have dementia. However, this increase is not uniform; in certain countries, such as China and India, the prevalence will more than double in the next few decades.

The report indicates that the majority of people with dementia, 60%, live in developing countries. By 2040, this percentage will have increased to 71%.

“Primary prevention (of dementia) should focus on targets suggested by current evidence; risk factors for vascular disease, including hypertension, smoking, type 2 diabetes, and hyperlipidemia,” the authors state. “The epidemic of smoking in developing countries and the high rising prevalence of type 2 diabetes in Asia are particular causes of concern.”

Lancet 2005;366:2112-2117.

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Normally, we humans think of ourselves as rational beings. A decision is made by me – the Agent – and I know perfectly what I want and how to get there. Enter cognitive neuroscience. From a multitude of studies, there is a consensus today that many decisions are not made through overt, conscious processing. A lot of work goes on behind the scenes and shapes the motivation and choices even in complex decision making.

Just think of the studies by Tanya Chartrand and her colleagues, as I wrote about in this article in the early days of Science & Consciousness Review. By presenting motivation relevant words (‘‘success’, ‘failure’ etc.) to subjects subliminally (without their conscious detection) the researchers were able to manipulate how they reacted when being given an easy or hard/impossible task. Without the subjects’ knowledge, Chartrand was able to produce emotional states in her subjects, e.g. being in a bad or good mood, by manipulating the motivational tone of the presented words. Best of all, her subject were not able to determine why they felt as they did.

Another well-supported idea about unconscious processes stem from research into subliminal perception and priming. From Phil Merikle’s article:

“Subliminal perception occurs whenever stimuli presented below the threshold or limen for awareness are found to influence thoughts, feelings, or actions. The term subliminal perception was originally used to describe situations in which weak stimuli were perceived without awareness. In recent years, the term has been applied more generally to describe any situation in which unnoticed stimuli are perceived.”

There are tons of empirical evidence for subliminal perception, and they all point to the fact that our behaviour is influenced strongly by unconscious processes. We are not the conscious, autonomous agents we think we are. At least not in the sense we usually think.

But if not all our choices are made on a conscious and “rational” level, why do we have the experience of being conscious agents of our actions? In a forthcoming interview I’m doing with Professor Shaun Gallagher at the Department of Philosophy, University of Central Florida, the terms agency and ownership are explored. This interview will be published in Science & Consciousness Review very soon. Here is an excerpt of the interview:

“Phenomenologically intentions in almost all cases come already clothed in agency – the ‘who’ question hardly ever comes up at the level of experience. The neural systems have already decided the issue – one way or the other – even if I’m wrong about who is acting, I am still attributing agency.

The mistake is to think that there is a necessary isomorphism between the phenomenological level and the neuronal level. But even if the neuronal processes can be defined as involving three steps, this does not mean that those three steps need to show up in consciousness. The wonderful thing about the “Who system” is that it’s neurological – and the results of its activation are hardly ever experientially manifested as “making a decision about who did the action.” Rather, the results of its activation are experientially manifested as “X’s action” where X is either you or me.

Of course experiments and pathologies may generate or reveal ‘who’ problems, but in normal ecological behavior it is generally clear whose intention/action it is, and as a result, the identification question – “Someone is intending to pick up the apple, is it me?” – just doesn’t come up.

Stay tuned for the full story.

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