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Neuroskeptic

Friday, January 6, 2017 4:05
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Over the Christmas break I discovered a blog written under the pen name Neuroskeptic.

“Neuroskeptic is a British neuroscientist who takes a skeptical look at his own field, and beyond. His blog offers a look at the latest developments in neuroscience, psychiatry and psychology through a critical lens.”

Neuroskeptic’s interests overlap topics covered in Intermediate Physics for Medicine and Biology. For instance, often Neuroskeptic writes about functional magnetic resonance imaging, a technique Russ Hobbie and I describe in Chapter 18 of IPMB.

“The term functional magnetic resonance imaging (fMRI) usually refers to a technique developed in the 1990s that allows one to study structure and function simultaneously. The basis for fMRI is inhomogeneities in the magnetic field caused by the differences in the magnetic properties of oxygenated and deoxygenated hemoglobin. No external contrast agent is required. Oxygenated hemoglobin is less paramagneticthan deoxyhemoglobin. If we make images before and after a change in the blood flow to a small region of tissue (perhaps caused by a change in its metabolic activity), the difference between the two images is due mainly to changes in the blood oxygenation. One usually sees an increase in blood flow to a region of the brain when that region is active. This BOLD contrast in the two images provides information about the metabolic state of the tissue, and therefore about the tissue function (Ogawa et al. 1990; Kwong et al. 1992).”

Neuroskeptic’s author is obviously an expert in this method, but is suspicious about some of its claims. Often he–I will use the masculine pronoun for convenience, but I have no idea about his gender–analyzes new papers in the field. For instance, in his recent New Year’s Eve blog post he writes

“Earlier this year, neuroscience was shaken by the publication in PNAS of Cluster failure: Why fMRI inferences for spatial extent have inflated false-positive rates. In this paper, Anders Eklund, Thomas E. Nichols and Hans Knutsson reported that commonly used software for analysing fMRI data produces many false-positives. But now, Boston College neuroscientist Scott D. Slotnick has criticized Eklund et al.’s alarming conclusions in a new piece in Cognitive Neuroscience. In my view, while Slotnick makes some valid points, he falls short of debunking Eklund et al.’s worrying findings.”

Another area Neuroskeptic analyzes is functional electrical stimulation. In Chapter 7 of IPMB, Russ and I write

“stimulating electrodes…may be used for electromyographic studies; for stimulating muscles to contract called functional electrical stimulation (Peckham and Knutson 2005); for a cochlear implant to partially restore hearing (Zeng et al.2008); deep brain stimulation for Parkinson’s disease (Perlmutterand Mink 2006); for cardiac pacing (Moses andMullin 2007); and even for defibrillation (Dosdall et al.2009). The electrodes may be inserted in cells, placed in or on a muscle, or placed on the skin.”

Two recent Neuroskeptic posts (here and here) analyze a controversial method of electrical stimulation called transcranial direct current stimulation (tDCS). I share his doubts about this technique, in which week currents (about 1 mA) are applied to the scalp. In a post last August, I hinted at some of my concerns, but my suspicions continue to grow. The electric fields induced in the brain by a 1 mA current to the scalp are minuscule.

Neuroskeptic also wonders if nonionizing radiation can cause cancer, a topic covered extensively in Chapter 9 of IPMB. He writes

“Does non-ionizing radiation pose a health risk? Everyone knows that ionizing radiation, like gamma rays, can cause cancer by damaging DNA. But the scientific consensus is that there is no such risk from non-ionizing radiation such as radiowaves or Wi-Fi. Yet according to a remarkable new paper from Magda Havas, the risk is real: it’s called When theory and observation collide: Can non-ionizing radiation cause cancer?… Non-ionizing radiation such as radiowaves and microwaves consists of photons, just like visible light, but at a lower frequency. Because the energy of a photon is proportional to its frequency, very high frequency photons (like gamma rays) have enough energy to disrupt atoms…But visible light can’t do this, and still less can microwaves or radiowaves. There’s no known mechanism by which such low-energy photons could harm living tissue – except that they can heat tissue up in high doses, but the amount of heating produced by radio and wireless devices is tiny.”

Neuroskeptic is not merely a debunker. Sometimes he examines promising new methods, but always with a questioning eye. For instance, his review of a paper developing new contrast agents for MRI is fascinating.

“In a new paper called Molecular fMRI, MIT researchers Benjamin B. Bartelle, Ali Barandov, and Alan Jasanoff discuss technological advances that could provide neuroscientists with new tools for mapping the brain.

Currently, one of the leading methods of measuring brain activity is functional MRI (fMRI)…. Recent work, however, holds out the hope that a future ‘molecular fMRI’ could be developed to extend the power of fMRI…. Molecular fMRI would involve the use of a molecular probe, a form of ‘contrast agent’, which would modulate the MRI signal in response to specific conditions.”

I would be interested in knowing what Neuroskeptic (I always want to type “the Neuroskeptic” but he never uses the definite article before his name, so I won’t either) thinks about claims of using the biomagnetic field as the gradient field in MRI, as I discussed in my June 2016 blog post.

Everyone has their own gimmick, and Neuroskeptic’s is that he keeps his real identity secret. Some of you are thinking: “Oh, I wish Roth would be anonymous! We hear far too much about him and his little dog Suki and his own research in this blog.” Well, sorry. It’s too late to change now, so you are stuck hearing about Suki and me in addition to learning about physics in medicine and biology. But if you want a well-written, anonymous, and sometimes dissenting view of neuroscience, read the Neuroskeptic.



Source: http://hobbieroth.blogspot.com/2017/01/neuroskeptic.html

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