v a l l e j o n o c t u r n o

True Science

A fascinating and sad article in The New Yorker about the mythologies of fire, ignorance, and science:

The fire moved quickly through the house, a one-story wood-frame structure in a working-class neighborhood of Corsicana, in northeast Texas. Flames spread along the walls, bursting through doorways, blistering paint and tiles and furniture. Smoke pressed against the ceiling, then banked downward, seeping into each room and through crevices in the windows, staining the morning sky.

Buffie Barbee, who was eleven years old and lived two houses down, was playing in her back yard when she smelled the smoke. She ran inside and told her mother, Diane, and they hurried up the street; that’s when they saw the smoldering house and Cameron Todd Willingham standing on the front porch, wearing only a pair of jeans, his chest blackened with soot, his hair and eyelids singed. He was screaming, “My babies are burning up!” His children—Karmon and Kameron, who were one-year-old twin girls, and two-year-old Amber—were trapped inside.

Willingham told the Barbees to call the Fire Department, and while Diane raced down the street to get help he found a stick and broke the children’s bedroom window. Fire lashed through the hole. He broke another window; flames burst through it, too, and he retreated into the yard, kneeling in front of the house. A neighbor later told police that Willingham intermittently cried, “My babies!” then fell silent, as if he had “blocked the fire out of his mind.”

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THE IMPRINTED BRAIN THEORY

Christopher Badcock writes at Edge 266:

What causes mental illnesses like schizophrenia and autism? We have long known that both tend to run in families and that if one of two identical twins has such a disorder, there is a much higher than average probability that the other will too. Autism is sometimes associated with genetic syndromes, such as Rett,  Down, and Turner's, Phenylketonuria, and Tuberous Sclerosis. The clearest single-gene cause of autism spectrum disorder (ASD) is Fragile X syndrome,  with a wide range of severity in symptoms and 25-47 per cent of affected males meeting the criteria for autism. But neither autism nor schizophrenia obeys classical Mendelian laws of inheritance in the way that Cystic Fibrosis or some types of colour blindness do.

However, there is also good evidence for social, environmental causes of mental illnesses. Studies of the Dutch wartime famine and of the Chinese famine of 1959–61 reported increased incidence of schizophrenia among children born just after the events. And a study of 2 million Swedish children born between 1963 and 1983 revealed a significant link between schizophrenia and poverty in childhood. Those with 4 out of 5 measured indicators of hardship had an almost  3-fold greater risk of schizophrenia than those with none. Where ASD is concerned, the exponential increase in diagnoses since the 1980s has prompted some to suggest environmental or social causes: most controversially, childhood vaccines like MMR. Autism can certainly result from ethanol or valproic acid poisoning during the mother's pregnancy, and in the 1964 rubella epidemic in the USA, the rate of incidence of autism exceeded 7 per cent at a time when the normal rate of diagnosis was not much more than a tenth of one per cent. ASD  can also be caused by thalidomide, where it affects about 5 per cent of those with birth defects attributable to this cause.          

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Deep Brain Stimulation (DBS)

A blog written by a person who has recently undergone DBS treatment:

Peggie, the Physicians assistant placed a transmitter over the stimulator pack that was implanted in my right upper chest wall and turned on the small computer it was connected to. Dr. Verhagen my neurologist came in and explained what was going to happen. Just to review, the DBS lead that was implanted has four contacts on it and they refer to them from zero to three. The goal is that two of the four contacts are in an area that they can be stimulated to arrest your tremors with no side effects. In order to make this determination they must test each contact individually, which make for a lengthy session. The zero lead is at the deepest point in the brain with the four lead being in the most superior position. The anticipation is that contact zero, one or two will be able to be programmed with enough voltage to arrest the tremors with out producing a consistent side effect such as tingling, facial twitch or speech impediment of any kind. After each lead is set at this point the Dr. observed my walking at a hurried pace down the hall way being careful to note my arm swing activity and gait pattern. this went on for about two hours at which point my wife and I sat in amazement as I sat there in complete and utter stillness, it was one of the most chilling and exhilarating moments of my life.

As we went throughout this process my wife later told me how she was amazed to watch as the tremor slowly disappeared as they adjusted the voltage. What I found interesting was the last flicker of tremor or muscle twitch to be controlled was at the lateral border of my left hand along my index finger. The reason this stands out is this is also the first sign of Parkinson's I noticed some 5 years ago.

I left the office in the most peaceful stress free mood I can ever remember, although I did have a major headache and was very fatigued from the whole experience. I was told to reduce my 25/100mg Carbidopa/levodpa med by 1/2 tablet per dose essentially cutting my daily dose by 1 1/2 tablets per day. After about a week I began to notice that the tremor was creeping back this caused some concern and frustration. After speaking with the PA at the neurologist’s office I was told it is not uncommon for this to happen as it is a process of balancing the level of medication and the intensity of the stimulator. I will be returning for a "Tune Up" in early December and most likely one or two more times to get everything in pristine working order.

All the simple shapes of nature

An interview with Benoit Mandelbrot, the inventor of fractal geometry, at NOVA:

Q: You've said, "My whole career is an ardent pursuit of the concept of roughness." What exactly do you mean by that?

Benoit Mandelbrot: Actually, this word roughness has different meanings according to context. Until I turned 20 and World War II ended, my life was becoming increasingly rough because of historical events over which no one I knew had any control. But after I turned 20, things changed. Without any clear plan or conscious decision, I became fascinated by, and then almost exclusively devoted to, all kinds of phenomena in which irregularity and variability dominate but are so great that they don't average out. This led me first to disbelieve and then to contradict in a radical fashion what everybody else was saying about those phenomena.

Q: In what way?

Mandelbrot: The predominant view of irregularity continues to follow Galileo's famous saying that the Great Book of Nature is written in the language of mathematics, the characters being circles, triangles, and other such shapes. A circle is perfectly regular. A triangle has three corners and is otherwise very smooth. And the great bulk of science studies smooth behavior, in particular using equations that assume that everything evolves in a very regular fashion.

Q: And you were studying the unsmooth.

Mandelbrot: That's right. I soon came to devote my life to phenomena that may belong to very different organized sciences but have the common characteristic of being irregular and fragmented at many scales. Like the weather, for instance. I could not possibly anticipate the level of complication this youthful choice would bring to my life trajectory. Each year of my life brought change in my interests, my tools, and my self-confidence, and I greatly learned from both the kind and the unkind comments I continually received.

But I was so alone that the direction I was following was not described by any existing word. In 1975, my work forced me to coin one: fractal. The Latin adjective, fractus, can denote anything that is like a broken-up stone—irregular and fragmented. The sudden realization that "fractal" deserved to be put in a book's title changed nothing in the substance but brought considerable change in the perception of my work. The word is now found in many dictionaries.

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BrainWorks

Edmund Rolls reviews Changeux's The Physiology of Truth:

Eminent French neuroscientists have a tradition of producing books on scientific topics of general interest for a wide audience. Here, Jean-Pierre Changeux draws on provocative new findings about the neuroscience and psychophysics of perception and judgement both in humans and in non-human primates. His case is that belief in objective knowledge is a characteristic feature of human cognition, and the scientific method its most sophisticated embodiment. Professor Changeux seeks to explain the ways in which modern science has made it possible to understand how language, truth and even morals are related to our genes and gene products, and to interactions with the environment. Changeux promises a radical understanding in neurophysiological terms of how perception, exploration, trial and error, cognitive games, the cultural sharing of language, and consciousness, can provide us with representations of reality that are both reliable and profound. In doing this, he draws on neuroscience, molecular biology, computer modelling, philosophy, linguistics and social psychology. 

The thesis of The Physiology of Truth is that our brains have evolved to provide representations of the world and to make judgements about it that are useful for action. Some of these actions take place in social contexts and involve planning many steps ahead. In order to operate in this realm, the brain has needed to develop an understanding of social systems, strategies to achieve goals, and useful heuristics for guiding behaviour, including social behaviour. These heuristics lead Changeux to consider the biological background to morality and how plans to achieve long-term goals are produced. In seeking to understand how animals, including humans, work, Jean-Pierre Changeux is attempting to develop a scientific understanding of how and why we behave as we do. 

Changeux draws on his own research—spanning the area from acetylcholine receptors to models of planning, how plans can be changed and the brain processes that may be related to consciousness—as well as on that of others. He appreciates the need to integrate knowledge derived from the spectrum of neuroscience disciplines to produce an explanation of how the brain functions. He realizes that, to understand how the brain performs its computations, it is important to know how single neurones are responding in particular situations, for it is single neurones that are the building blocks of computation by the brain. Single neurones are the information-processing elements of the brain; they act as non-linear computational devices and exchange information among themselves. It is only by analysing the spiking activity exchanged among neurones that one can understand how representations of information are provided by neural activity. It is then possible with modern computational neuroscience to take the responses of large groups of neurones and to understand their collective computational properties, as demonstrated in a series of interesting contributions by theoretical physicists and mathematicians (Amari, 1982; Hopfield, 1982; Amit, 1989; Hertz et al. 1991; Rolls and Deco, 2002). Jean-Pierre Changeux has worked in many of these different areas.

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10 Important Differences Between Brains and Computers

From Developing Intelligence:

Although the brain-computer metaphor has served cognitive psychology well, research in cognitive neuroscience has revealed many important differences between brains and computers. Appreciating these differences may be crucial to understanding the mechanisms of neural information processing, and ultimately for the creation of artificial intelligence. Below, I review the most important of these differences (and the consequences to cognitive psychology of failing to recognize them): similar ground is covered in this excellent (though lengthy) lecture.

Difference # 1: Brains are analogue; computers are digital

It's easy to think that neurons are essentially binary, given that they fire an action potential if they reach a certain threshold, and otherwise do not fire. This superficial similarity to digital "1's and 0's" belies a wide variety of continuous and non-linear processes that directly influence neuronal processing.

For example, one of the primary mechanisms of information transmission appears to be the rate at which neurons fire - an essentially continuous variable. Similarly, networks of neurons can fire in relative synchrony or in relative disarray; this coherence affects the strength of the signals received by downstream neurons. Finally, inside each and every neuron is a leaky integrator circuit, composed of a variety of ion channels and continuously fluctuating membrane potentials.

Failure to recognize these important subtleties may have contributed to Minksy & Papert's infamous mischaracterization of perceptrons, a neural network without an intermediate layer between input and output. In linear networks, any function computed by a 3-layer network can also be computed by a suitably rearranged 2-layer network. In other words, combinations of multiple linear functions can be modeled precisely by just a single linear function. Since their simple 2-layer networks could not solve many important problems, Minksy & Papert reasoned that that larger networks also could not. In contrast, the computations performed by more realistic (i.e., nonlinear) networks are highly dependent on the number of layers - thus, "perceptrons" grossly underestimate the computational power of neural networks.

Difference # 2: The brain uses content-addressable memory

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Views of the Brain

Morbid anatomy of the human brain 1828

Consciousness like Nicotine

From Neuroanthropology ,a science blog, on Changeux's view of the mind's "representations":

Changeux argued something completely different—the importance of the basic mechanisms and processes of the brain, the power of epigenetics and brain-environment interactions, and the role of natural selection in shaping the brain in the past and in present. As an Amazon reviewer puts it about a more recent Changeux book, The Physiology of Truth, this work “offers an evidence-based challenge to two popular ideas: namely, the largely functionalist idea that the brain is nothing more than a sophisticated computer and, alternatively, the nativist idea that the brain is ‘the embodiment of a strictly predetermined genetic inheritance’.”

For many years, Changeux has also been after bigger fish, moving from neurons themselves to neuronal communication and systemic brain function. Rosenfield and Ziff’s briefly summarize two main ideas, Hebbian learning (neurons that fire together, wire together) and specialized neurotransmitters released by regulatory networks that can reinforce neuronal connections throughout entire sections of the brain. Changeux’s long-term work has focused on those regulatory networks, in particular on the neurotransmitter acetylcholine:

It was long known that nicotine acts on the same receptor as the neurotransmitter acetylcholine. Changeux recognized that this could explain both nicotine’s obvious benefits—greater concentration, relaxation, etc.—as well as the drug’s more puzzling long-term effects… Changeux found that nicotine, by attaching to the same receptors as acetylcholine, reproduces some of the benefits of acetylcholine by reinforcing neuronal connections throughout the brain. Nicotine is not exactly the same chemically as acetylcholine, but can mimic its effects. Changeux’s lab has since focused on the workings of the nicotine/acetylcholine system, and he has attempted to explain how all such regulatory systems, working together, can produce the experience we call consciousness—as well as more abstract concepts like truth.

Cajal on Consciousness

About Textura:

The origin of Textura comes from a serie of four conferences that Cajal pronounces in Barcelona in 1892 in the ‘Academia de Ciencias Médicas’, The contribution of its conferences are published in the ‘Revista de Ciencias Medicas de Barcelona’ under the title ' El nuevo concepto de la Histología del Sistema Nervioso’ (The new concept of the Histology of the Nervous System). Translated to German and French by Held and Azoulay, and published in ‘Archiv für Anatomie und Physiologie’ and the ‘Bulletin M’edicale de Paris’, they cause great impression in the international scientific environment, ignorant in their majority of the Spanish scientist's new theories.

The polemic raised with the new contributions by Cajal (doctrine of the neuron, existence of the sinapsis, neuronal polarization, organization of the cerebellum cortex...) forced him to enlarge them in a new a book with the title ' Les Nouvelles idées sur la structure du Système Nerveux chez l'Home et chez les Vertebrés' published in 1894.

The success of this book (three editions in three months) seems to be in the origin of an ambitious project: to collect all his works in a great masterpiece intending ' to pick up those infinites details of form and cellular structure.... and also try to set up, if possible, a theoretical science'.

Thus, between 1899 and 1904 ' Texture of the man's nervous system and of the vertebrates' is published originally in booklets of scarce edition financed by the author. In this work reflects fifteen years of investigations, exploring the whole complex structure of the nervous system, from the general morphology of the neuron to the structure of the ganglion of the intestinal plexus.

The success of the book was so important that five years later in 1909, the editorial Maloine of Paris publishes in French the second edition: ' Histologie du Systéme Nerveux de l'Home et des Vertebrés', better known than the first one by the scientific comunity, being considered as the original edition of Cajal's work.

strelkaphotography

strelkaphotography on flickr