Archive for the ‘neuroscience’ Category

mysticfigure.jpgA new report in Nature demonstrates that electrical stimulation of the temporoparietal junction in the brain induces a sensation of the presence of an illusory “shadowy person”. One of the hallmarks of certain forms of schizophrenia is just this phenomenon: the eery feeling of someone’s presence. Now, it has been demonstrated in a study using electrical brain activation in a person without a history of psychiatric problems.

Basically, the study was performed on a subject that was at the preoperative stage of surgery for epilepsy. A normal procedure is to anaesthesize the patient before opening the skull, and then wake the patient up before stimulating the brain. The aim of such stimulation is to find the location of epilepsy onset, as well as to stimulate the areas surrounding this region, in order to map functionally important regions (e.g. language that are important in language). Such preoperative procedures are known to lead to a better surgical sensitivity, i.e. the ability to remove all of the abnormal tissue, and a higher surgical selectivity, i.e. avoding removal of normal tissue. In this way, neurosurgeons often evoke a number of sensations and behaviours in patients, including the disruption of speech, visual phosphenes, and memory deficits.

In the present case, the neurosurgeons found that electrical stimulation lead to a feeling of the presence of another person. Moreover, the patient reported that this figure was taking the same posture as herself, and even sometimes interfering with a task she was performing:

When stimulated (…) the patient had the impression that somebody was behind her. Further stimulation induced the same experience, with the patient describing the “person” as young and of indeterminate sex, a “shadow” who did not speak or move, and whose position beneath her back was identical to her own (“He is behind me, almost at my body, but I do not feel it”). (…) Further stimulations [other location] were applied while the seated patient performed a naming (language-testing) task using a card held in her right hand: she again reported the presence of the sitting “person”, this time displaced behind her to her right and attempting to interfere with the execution of her task (“He wants to take the card”; “He doesn’t want me to read”).

Stimulation of the temporoparietal junction (shown with an arrow in the image above) thus seems to distort some kind of body image, or maybe even efference copy (PDF) of self-actions. Both functions that are dramatically affected in abnormal brain states following certain kinds of delusional schizoprenia and brain injury.

The finding also nicely relates to the Swiss group’s earlier study combining EEG, TMS and the study of an epilepsy patient, where it was found that disruption of the temporoparietal junction function led to an “impaired mental transformation of one’s own body”. Here, the researchers concluded that:

the [temporoparietal junction, TPJ] is a crucial structure for the conscious experience of the normal self, mediating spatial unity of self and body, and also suggest that impaired processing at the TPJ may lead to pathological selves such as [out-of-body experience].

Here is the full story:

Induction of an illusory shadow person
By Arzy et al
Nature 443, 287

Stimulation of a site on the brain’s left hemisphere prompts the creepy feeling that somebody is close by.

The strange sensation that somebody is nearby when no one is actually present has been described by psychiatric and neurological patients, as well as by healthy subjects, but it is not understood how the illusion is triggered by the brain1, 2. Here we describe the repeated induction of this sensation in a patient who was undergoing presurgical evaluation for epilepsy treatment, as a result of focal electrical stimulation of the left temporoparietal junction: the illusory person closely ‘shadowed’ changes in the patient’s body position and posture. These perceptions may have been due to a disturbance in the multisensory processing of body and self at the temporoparietal junction.
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1. Laboratory of Cognitive Neuroscience, École Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland
2. Presurgical Epilepsy Evaluation Unit, University Hospital, Geneva 1211, Switzerland
3. Department of Neurology, University Hospital, Geneva 1211, Switzerland
4. Center for Cognitive Neuroscience, Dartmouth College, Dartmouth, New Hampshire 03755, USA



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einstein.jpgWhat characterizes Albert Einstein‘s brain? Why did he become a genius? Can we trace it down to brain-related factors? A growing literature on the relationship between intelligence and brain structure and function has demonstrated several relationships. Those studies, however, are typically based on comparison of brains of high versus mean IQ groups. Studying individual geniuses and what is special about their brains are rare in the scientific literature. However, there are a few exceptions.

In a study by Colombo et al in Brain Research Reviews, the brain of Albert Einstein is studied and compared to four age-matched individuals without any known neurological or psychiatric symptoms. The researchers found that

Einstein’s astrocytic processes showed larger sizes and higher numbers of interlaminar terminal masses, reaching sizes of 15 μm in diameter.

And they further notice that

These bulbous endings are of unknown significance and they have been described occurring in Alzheimer’s disease

…which would mean that, if anything, the size and number of interlaminal terminal masses in Einstein’s brain would make it more like an Alzheimer-patient than like a genius.

Colombo and colleagues are indeed sceptic about the findings and interpretations in the literature on Einstein’s brain. But why do this study in the first place? I’m baffled — to put it mildly — that this kind of study is published in a well-esteemed (well, any) scientific journal. This due to especially three factors relating to the validity of the study:

  1. There are only four control subjects. This provides no information about what the population as a whole looks like for the given brain measurement. IOW, we cannot know anything about the natural variance in the population of our measures, let alone know much about the mean value. Given this, the up-to-15-μm-diameter interlaminal terminal masses means nothing, since we cannot know anything about whether Einstein’s brain is special
  2. One is studying an old and degenerated brain. The fact that the study is of Einstein’s brain at a high age (76 years) seems irrelevant to discover what made his brain so special during the age at which he formulated and developed his theoretical ideas, i.e. decades earlier. This period not only includes the time at which he wrote about relativity, but also an earlier and less known period when he wrote the Annus Mirabilis Papers. This latter series of articles are concerned with the photoelectric effect, also recognized as papers that alone deserve a Nobel prize. And those papers were even written by Einstein during his spare time!
  3. Why not study a group of geniuses? Indeed, why only rely on one data point? Why not include a larger sample of geniuses, not only from physics, but from other sciences? Einstein was not the only genius around. Living in Denmark and passing through the Copenhagen University physics buildings regularly, I am immediately reminded of Niels Bohr, a contemporary to Einstein that matches Einstein’s genius in every respect. It would thus be much more interesting to see a group study of geniuses. It might be hard to do a genius post-morten study for both practical and ethical reasons, but one can do in vivo studies of today’s geniuses, right? One data point, even if it’s Einstein, is really not enough. Doing a group study we could also ask questions such as whether there are differences between male and female geniuses, or whether the develop and age different from the general population.

Einstein’s brain is indeed an interesting topic, but in order to make valid inferences from a study of his brain, we should consider including his brain among a number of related geniuses. Doing any kind of study of one genius’ brain is unlikely to produce any valid finding at all.


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In an interesting paper in the latest version of Progress in Neurobiology, Yuri I. Arshavsky from UCSD writes about the epistemological dualism that exists in modern neuroscience. basically, Arshavsky claims that there is a covert dualism in the way that neuroscientists are treating mind-related topics, especially the study of “consciousness”. Indeed, as he claims:

This covert dualism seems to be rooted in the main paradigm of neuroscience that suggests that cognitive functions, such as language production and comprehension, face recognition, declarative memory, emotions, etc., are performed by neural networks consisting of simple elements.

This might initially sound a bit strange. Is not cognitive functions such as face perception due to operational simple elements? Face perception as such is a combination of many simple processes that operate in unison. So what is Arshavsky proposing? Indeed he suggests the existence of a certain kind of brain cells:

(The) performance of cognitive functions is based on complex cooperative activity of “complex” neurons that are carriers of “elementary cognition.” The uniqueness of human cognitive functions, which has a genetic basis, is determined by the specificity of genes expressed by these “complex” neurons. The main goal of the review is to show that the identification of the genes implicated in cognitive functions and the understanding of a functional role of their products is a possible way to overcome covert dualism in neuroscience.

So there should exist a subset of neurons that integrate information from a variety of input. This sounds strange, since all neurons integrate inputs from thousands of inputs, many from a large variety of inputs. So what are complex neurons? Here, we are told that:

(…) neural networks involved in performing cognitive functions are formed not by simple neurons whose function is limited to the generation of electrical potentials and transmission of signals to other neurons, but by complex neurons that can be regarded as carriers of “elementary” cognition. The performance of cognitive functions is based on the cooperative activity of this type of complex neurons.

In this way, complex neurons seem to be integrative neurons, i.e. cells that integrate information from a variety of processes. This could include the multi-modal neurons found in the functional sub-structures of the medial temporal lobe, such as the hippocampus, perirhinal, entorhinal and temporopolar cortex. But would it not mean the colour processing nodes in the visual cortex? Which IMO leads us back to a basic question: what is a functional unit in the brain. yes, the neuron is a basic building block of information processing in the brain. But what is special about language, memory and so forth in the brain?

It is possible that Arshavsky is not radical enough: what we should seek out is to avoid using generalistic and folk-psychological concepts in the first place. We should possibly not study “language”, “memory” or “consciousness”, since these concepts will always allude to fundamental assumptions of “language-ness”, “memory-ness” and “consciousness-ness”, IOW that there is something more to explain after we have found out how the brain produces what we recognize and label a cognitive function.

Maybe neuroscientists are not using a poor strategy after all? Maybe ignoring the past history of philosophy of mind is the best solution. I’m not sure (nor am I sure that I represent Arshavsky’s view properly). But how we choose to label a cognitive function depend on our past historical influence and learning, as well as our current approach.


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Research on the neurocognitive mechanisms underlying human production and experiece of music is one of most rapidly expanding subfields of contemporary neuroscience. You may recall that back in May I noted that both the Annals of the New York Academy of Sciences and Cognition recently has published newly edited special issues on this topic.

A new book by Daniel Livitin, an investigator at the department of psychology at McGill University (and former music producer), presents parts of this exiting research to the general public: This is Your Brain on Music (Dutton 2006). As a teaser, you may first want to hear an interview with Livitin on NPR, which you can find here.

Canada is in many ways the current epicenter of neuromusicology research. Isabelle Peretz, at the University of Montréal, and Robert Zatorre, also at McGill, are perceived by most to be the leaders of the field. Recently, Peretz and Zatorre have established a brand new center for research into the biological foundations of music called BRAMS (Brain, Music and Sound), which is scheduled to host no less than “a core group of seven faculty together with two to three positions for junior investigators, as well as 10 postdoctoral fellows and 20 graduate students,” according to its website. But neuromusicology is also booming in Europe. Starting this year, a project called “Tuning the Brain for Music”, and funded by the EU, will draw together researchers at universities in Finland, Germany, Sweden, Italy, and Canada (again!) in an attempt to “gain a deeper insight into the relationship between music, emotions and brain functions”.

Much of the interest in the neural underpinnings of music stems from a deep-seated interest in the evolutionary origins of music – as this recent article from The Boston Globe testifies. Many deeply speculative hypotheses have been advanced as to why homo sapiens has evolved this curious passion for music. However, in recent years more serious papers considering this question have also been appearing, integrating data from comparative studies in animal cognition, neuroscience, and genetics. Let me especially recommend these two papers:


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Neuroethics is an inherently historical field, although this is not always pointed out: the cases and experiments discussed by the neuroethics literature took place sometime in the past, and in many cases it might be beneficial to also consider the historical context when examining them. What were the theoretical assumptions that informed the experiments? What social and political factors surrounded some specific case story? An interesting example of this strategy is three new papers on “Neurosciences and the Third Reich” published in the September issue of Journal of the History of Neuroscience. As Axel Karenberg notes in an accompaning editorial: “What and how much can we learn from the past to help us better plan for the future? Every interaction with Nazism forces us to confront this question.”

The first of the three papers, Florian Steger’s essay “Neuropathological research at the ‘Deutsche Forschungsanstalt für Psychiatrie’ in Munich…”, examines how German scientists took advantage of the Nazi regime’s euthanasia policies to conduct unethical experiments on people, often children, who were later killed.

The second, Florian Schmaltz‘s paper “Neurosciences and Research on Chemical Weapons of Mass Destruction in Nazi Germany”, looks at the neurochemical weapons development program started and later discontinued in 1942. While the resulting nerve gasses were never widely used during World War II, the German researchers responsible for developing them were later, after the war, recruited by the allied forces.

And the third, an essay by Jürgen Pfeiffer entitled “Phases in the postwar German reception of the ‘Euthanasia Program’ (1939-1945)…”, explores how Germany after the war refused to deal with this dark chapter of German neuroscience and medical research.

At the end of his editorial Alex Karenberg ponders what ethical lessons can be extracted from examining the history of neuroscience in the Third Reich and draws three conclusions which I here quote:

1: Our view of the natural sciences has changed since the development of atomic weapons and the Nuremberg Trials. “Pure science” — the search for truth in ivory towers — no longer exists. Scientists today bear a moral responsibility for consequences and aberrations. The history of medicine in the Third Reich made abundantly clear how dependent medical research is on political pressure, social expectations, and financial considerations.
This is as true today as it was then, even when the circumstances have changed. The task of medical historians is to make this clear to current and future students and scientists.

2: Nazi medicine makes equally clear that it is not a question of good versus bad research — but that medical knowledge is always in conflict with ethical values. Ever since medicine became a true natural science, this union has had an inherently destructive potential. Where and whenever the desire for scientific progress dominates and is made superior to all other moral values, that is where and when the “dark side” of medicine will be found: in the Third Reich, in other totalitarian regimes, and even in democratic states lacking strong ethics. Inhuman and inhumane progress is possible in any kind of research when the only goal is the acquisition of knowledge. This is and shall remain true.

3: Finally, writing history is not the same as personal memory. History is constructed memory based on dates and facts. Personal memory is subjective and emotional. Society and above all science needs both forms of cultural remembrance in order to fully understand itself. This is especially the case for German medicine when recalling those crimes committed in the name of science. I would thus like to conclude this introduction with two citations dealing with the power of self-criticism and memory. The first is from the Book of KingsI (19:4): “I am no better than my ancestors.” The second is from a speech given by former German President Richard von Weizsäcker: “The secret of reconciliation is remembering.”

It would certainly be interesting, in the future, to see a more direct integration of historical research with neuroethics discussions.


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brainimagingbehavior.jpgIt’s not every day that we see a new journal emerging. However, Springer now launches a new journal called Brain Imaging and Behavior. According to the mission statement, the goal of the journal is to

publish innovative, clinically-relevant research using neuroimaging approaches to enhance the understanding of neural mechanisms underlying disorders of cognition, affect and motivation, and their treatment or prevention.

In this sense, the journal seems to have the ultimate goal of disease understanding and treatment. However, as they write, research on individual differences in representation of normal functions is important as well. What I find particularly interesting is that “brain imaging” is taken to imply a whole range of imaging methods in the study of the brain. It involves everything from the higher cognitive functions to molecular imaging methods. This implies the different approaches that involves genetics, behaviour and neuroimaging, AKA imaging genetics.

Brain Imaging and Behavior sounds like a very interesting initiative. I had problems finding the first online articles (this link). And would it not be better if the journal, just as any science journal, was free? It would be good if they followed the example of PLoS.


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drosophila.jpgWhat is the nature of instincts and inborn behaviour? The cover article of this week’s issue of Current Biology is an article by Kim et al. on how the central nervous system produces inborn behaviour. The researchers found that the innate behavior is initiated by a “command” hormone that orchestrates activities in discrete groups of peptide neurons in the brain (peptide neurons are brain cells that release small proteins to communicate with other brain cells and the body). The action of the hormonal influence, however, was not an all-at-once phenomenon. The ecdysis-triggering hormone or ETH, activated discrete groups of brain peptide neurons in a stepwise manner, making the fruit fly perform a well-defined sequence of behaviors.

Says Michael Adams, the research team leader:

Our results apply not only to insects; they also may provide insights into how, in general, the mammalian brain programs behavior, and how it and the body schedule events. By understanding how innate behavior is wired in the brain, it becomes possible to manipulate behavior — change its order, delay it or even eliminate it altogether — all of which opens up ethical questions as to whether scientists should, or would want to, engineer behavior in this way in the future”

An instinct is an inborn disposition for a specific kind of behaviour. Although we often regard instinctual behaviours to be in the domain of non-human animals, humans also have well-known instincts, the most known are found in infants. However, many researchers suggest that other behaviours — such as altruism, disgust, face perception, and language acquisitions are also instinctual, at least in part so.

Would the present result mean that behaviour — let’s start with instinctual behaviours — could be edited? Adams seems to think so, and in the Drosophila it certainly seems to be the case. Since the steps leading to the well-orchestrated instinctual behaviour were identified, and the neurochemical properties of these circuits are — or are soon — known, it should be a trivial thing to alter the behaviour at any stage during the process. What about human behaviour, then? In principle, the same idea should apply.

Complaints will certainly arise that “human behaviour is so much more complex than instincts”. Indeed it is. But recall studies of voluntary action, of subliminal perception and of automaticity (e.g. riding a bike). These behaviours resemble instinctual behaviour a lot. They are not under conscious control, or are at least not initiated by such. In this sense, it might be that even human behaviour can be edited in much the same way as the Drosophila.

Admitted, this study only focuses on the ecdysis sequence behaviour in an insect. So we need more advanced (still instinctual) behaviours to believe the story. Replications & variations as always… But hey, maybe this will end up as the next cure for odontophobia…?


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