Monthly Archives: October 2011

News Round-Up: October 2011 5th Edition

Researchers used EEG and fMRI to investigate lucid dreamers. The lucid dreamers were scanned whilst asleep and signalled that they were dreaming of clenching their fists by moving their eyes horizontally several times. Only two episodes were captured but they displayed similar activity to hand clenching. However these results should be viewed with caution as only two episodes were captured and it will be interesting to see the results of replication studies.

The Picalm gene product which has been linked to Alzheimer’s Disease has been investigated in one study where the researchers found evidence that it disrupted the ability of Amyloid to interfere with endocytosis which could inform further research in this area.

Psychiatry 2.0

There’s an interesting open letter regarding the use of blogs in research in which the authors compare the use of blogs with the traditional peer review process (via @EvoMRI).

Evolutionary Psychiatry

In research published in the Open Access journal ‘Mobile DNA’ , the researchers compared human and Chimpanzee DNA and found that the main differences resulted from the so-called junk DNA. The researchers conclude that this is consistent with the theory that the genetic differences between Chimpanzees and humans are mainly differences of gene regulation rather than gene differences.

In a post-mortem study in which researchers used 49000 gene probes in 269 brains across the lifespan, researchers obtained over a trillion pieces of information and found evidence that the expression of genes in the prefrontal cortex peaks just after birth. Following this a number of genes switch off and reduce towards middle age. In older adults the genes are increasingly expressed. The write-up covers a number of other studies with complex but very interesting results. In one study using 1.4 million probes to examine 57 human brains, the researchers found evidence that the brain location and timing influenced gene expression more significantly than individual variation.

Appendix

News Roundup 2008

News Roundup 2009

News Roundup 2010

Psychiatry 2.0

 

 

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

 

New Version of Video on Insular Cortex Uploaded

I’ve just uploaded another version of the Model of the Insular Cortex with improved audio.

Blog Articles on the Insular Cortex (Brodmann Areas  13, 14 and 52)

YouTubing the Insular Cortex  What does the Insular Cortex Do Again? Insular Cortex Infarction in Acute Middle Cerebral Artery Territory Stroke The Insular Cortex and Neuropsychiatric Disorders Developing a Model of the Insular Cortex and Emotional Regulation Part 1 Developing a Model of the Insular Cortex: A Recap  The Relationship of Blood Pressure to Subcortical Lesions  Pathobiology of Visceral Pain  Interoception and the Insular Cortex  A Case of Neurogenic T-Wave Inversion   Video Presentations on a Model of the Insular Cortex  MR Visualisations of the Insula  The Subjective Experience of Pain*  How Do You Feel? Interoception: The Sense of the Physiological Condition of the Body  How Do You Feel – Now? The Anterior Insula and Human Awareness   Role of the Insular Cortex in the Modulation of Pain  The Insular Cortex and Frontotemporal Dementia   A Case of Infarct Connecting the Insular Cortex and the Heart  The Insular Cortex: Part of the Brain that Connects Smell and Taste?   Stuttered Swallowing and the Insular Cortex

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

Videos on the Ear Uploaded

I’ve just uploaded some instructive videos from a 1940 Bosse Production on the structure and function of the Ear. The material (now in the Public Domain) is very clearly explained and although in black-and-white illustrates the points very well.

Sound Waves

Anatomy of the External Ear

Anatomy of the Middle Ear

Physiology of the Middle Ear

Structure of the Inner Ear

Physiology of the Inner Ear

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

Can We Understand the Riddoch Phenomenon?

I would argue that the recent findings of Gallant and colleagues present a turning point in the field of neurophysiology. They have provided an intuitive way of understanding brain activity in the visual cortex. The essential findings of the study were that the researchers were able to reconstruct complex visual stimuli that had been presented to subjects on the basis of their brain activity alone. Thus they were able to ‘see’ the activity in the brain. I will not elaborate further on the details of the study which I have discussed previously (see this post). The nature of their investigations – looking specifically at the visual cortex lends itself to this type of visual analysis*. The video below demonstrates the outcome of their approach.

Video Reconstructions of Clips Presented to 3 Subjects. The average of the best-fit clips is on the left, while those on the right are the best fit clips. Each row represents a single subject.

Now that the methodology has been established it is possible for the researchers to turn to other phenomenon and start to ask questions which were solely the domain of cognitive psychologists, phenomenologists and philosophers and in so doing to integrate their findings with those of practitioners from these other disciplines. One interesting phenomenon is that of Cortical Blindness where a person may experience visual sensations but have no conscious awareness of these phenomenon. They can see in one sense and yet cannot see in another. Cortical blindness encompasses a variety of phenomenon and there are a corresponding variety of causes. One instance of Cortical Blindness is known as the ‘Riddoch phenomenon‘ described by Riddoch in 1917. A person exhibiting the Riddoch Phenomenon when presented with a stationary object in their field of vision and will be unable to identify this object. However when the subject is presented with a moving object they will be able to recognise the object’s movement. This is a rather simplistic description of the phenomenon and indeed there are various nuances. For instance one group have identified that stimuli of certain colours are more likely to produce this phenomenon than others. Whilst the original description by Riddoch focused on injury to the Occipital Cortex, other groups have identified the same phenomenon resulting from lesions elsewhere (see this freely available paper).

One remarkable figure in the field of Neurology who for some time was the editor of the Journal Brain was Sir Gordon Holmes. His pioneering work occurred in the first World War when he treated soldiers with head injuries. He closely followed Riddoch’s work and I was interested to learn of his views on the ‘Riddoch Phenomenon’. In his 1918 paper ‘Disturbances of Vision by Cerebral Lesions‘ Holmes writes that in those areas where the static stimuli cannot be appreciated but where the moving stimuli can be seen

But I have always found that the acuity of vision in these areas is considerably diminished; the patient may be uncertain of the stimulus, or he may describe it as indistinct, or as if seen through a mist; and on testing, it frequently happens that he responds only when the movement is abrupt and repeated but fails to do so when it is slow and gradual‘.

He further quotes from William James who writes about the extramacular parts of the retina thus

Its main function is that of a sentinel which when beams of light move over it, cries: ‘Who goes there?’ and calls the fovea to the spot

Holmes then moves to the point of his argument

I would like to say that the condition described by Riddoch should not be spoken of as a dissociation of the elements of visual sensation, since it is only a condition of visual hypoaesthesia in which the stronger and more adequate stimuli alone excite sensations‘.

Holmes left a remarkable legacy and his clinical acumen played a significant role in understanding of human visual perception. Thus we should pay close attention to his words above. Whilst the apparent dissociation of static and dynamic stimuli in the realms of perception seem perplexing and hint at sophisticated parcelling of function within the visual cortex, Holmes suggests instead that we consider instead a hierarchy of stimuli which are ever more likely to precipitate a perceptual response. What if we could transport Holmes through time to the laboratory of Gallant? What questions might he ask and what might he think of the technology? What might he expect to see in the reconstructed moving images.

Supposing subjects with Riddoch Phenomenon were to be investigated using the above methodology. They were presented with many hours of moving images whilst they were scanned. Whether there was any activity in the Visual Cortex would be the first telling finding. If Holmes were correct, it may be that activity in the Visual Cortex occurred only when the image stimuli were moving above a threshold velocity. Furthermore this would correspond to a conscious experience. Then similarly further moving images could be presented and reconstructed from recorded brain activity using the research paradigm. Where these findings to deviate from the predictions of Holmes, they would provide invaluable insights into the mechanisms behind this phenomenon. Suppose for instance that static images produced both activity within the visual cortex and that they could also be reconstructed from the brain activity. This would mean that these areas within the visual cortex are not necessary for conscious experience of visual stimuli. Answering questions of this sort would offer useful insights into an understanding of the qualia of conscious experience. These are interesting times for understanding such phenomenon.

References

Holmes G. Disturbances of the Vision by Cerebral Lesions. Brit J Opthal. 1918. 2. 353. Reproduced in Selected Papers of Sir Gordon Holmes. Compiled and Edited by F.M.R Walshe. Macmillan. 1956.

* Were the analysis to have involved the auditory cortex for instance, the researchers would have needed to reconstruct the auditory stimuli and we would be listening to the reconstructed sounds rather than the reconstructed moving images.

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

New Videos on The Eye Uploaded

I’ve just uploaded some new videos (or old depending on your perspective). They’re taken from a 1941 film  by Boss Productions which is in the Public Domain and can be found at the Prelinger Archives.  Anyhow I thought they were quite instructive as introductory material. While many things have moved on in 70 years there is still much to be said for clear, well thought out educational material.

The Anatomy of the Eye

Refraction in the Eye

Accommodation in the Eye: The Role of the Lens

Accommodation in the Eye: The Role of the Iris

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

News Round-Up: October 2011 4th Edition

There is an article at Scientific American on the global population which is expected to reach 7 billion. Although there have been other estimates which suggest it has already happened there has been no Global Census. The author of this article suggests that a new city of 1 million people needs to be built every 5 days to meet the expected population increase over the course of this century. While this is speculation it is interesting to note that there are significant differences between urban and rural areas in the pattern of mental illnesses (e.g see here). Were such demographic shifts to be realised it would have significant implications for the configuration of psychiatric service provision.

Having a preference for sweets rather than crackers or no snacks was associated with increased likelihood to engage in altruistic acts in this study. The former group also scored more highly on the personality trait of agreeableness.

Researchers have investigated resting state activity in people with agenesis of the Corpus Callosum. Agenesis of the Corpus Callosum is a condition in which the fibres connecting the right and left sides of the brain are absent during development. Previously this was investigated by looking at people who had undergone severance of the fibres in the Corpus Callosum for treating intractable epilepsy. Resting state activity is the activity that occurs in the brain when a person is resting and not engaged in any obvious activity – wakeful rest. The brain areas that are active when recorded using functional Magnetic Resonance Imaging form a characteristic network which has been assumed to involve a communication between both hemispheres of the brain. The researchers in this study found patterns of activity similar to those in people with an intact Corpus Callosum and this raises new questions about the nature of the resting state network.

There is a case report of a person who developed Hashimoto’s Encepalopathy. The researchers completed a neuropsychological assessment and after resolution of the encepalopathy found a residual executive impairment. However case studies are useful in generating hypotheses for further replication studies as there is so much variation between people.

The researchers in this Korean study provided further evidence of differences in the rate of cognitive decline in three forms of dementia – Parkinson’s Disease with dementia, Vascular Dementia and Alzheimer’s Disease.

The authors of a meta-analysis of Diffuse Tensor Imaging studies concluded that Mild Cognitive Impairment differed from Alzheimer’s Disease in that in the former there appeared to be sparing of changes in the frontal and occipital lobes whereas in the latter changes were evident in all regions of the brain.

There are some interesting pieces at the Alzheimer’s Research Forum

There is a write-up of a study in C.Elegans worms which looks at heritability of longevity. The researchers found that the methylation of DNA in the worms accounted for up to 30% of the variation in longevity. They argue that this is a non-DNA form of heritability. If these findings were generalised to humans it would mean that in studies of aging, researchers would need to look for patterns of methylation of DNA and not just for longevity genes in order to gain a better understanding of aging.

There is also a review of a neuroimaging supplement in the Journal of Alzheimer’s Disease which looks at developments in this area.

Also at the Alzheimer’s Research Forum Li and colleagues review the evidence on homocysteine as a risk factor for Alzheimer’s Disease.  They conclude that the evidence points to a relationship between homocysteine levels and Alzheimer’s Disease but studies investigating a role for Vitamin B have produced mixed results.

In this 11 C PiB study there was found to be no association between Beta-Amyloid load and rate of cortical atrophy over time. Pittsburgh B is a compound which is used to identify Beta-Amyloid Plaque which is central to the Alzheimer’s Disease process according to the Amyloid Cascade Hypothesis. Nevertheless the findings in this study may point to independent roles for Amyloid Beta load and cortical atrophy in the development of Alzheimer’s Disease.

Psychiatry 2.0

One study provided evidence that high-quality research published in Open-Access form has higher citation rates than equivalent articles in non-Open-Access format (via @BoraZ).

There’s an interesting video on the semantic web below.

Web 3.0 from Kate Ray on Vimeo.

Appendix

News Roundup 2008

News Roundup 2009

News Roundup 2010

Psychiatry 2.0

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.

In Support of Method: Videos Updated

A while ago I wrote a response to Feyerabend’s ‘Against Method’. Feyerabend is a contemporary of Thomas Kuhn and each drew on the other’s work. The premise of Feyerabend’s work was that ‘anything goes’ in science. I also created a series of videos about this response and have now merged these videos together so that it can be viewed as a single video rather than needing to find each of the segments.

Appendix

Review of Thomas Kuhn’s ‘The Structure of Scientific Revolutions’.

For a review of the Introduction see here.

For a review of Chapter 1 see here.

For a review of Chapter 2 see here.

For a review of Chapter 3 see here.

For a review of Chapter 4 see here.

For a review of Chapter 5 see here.

For a review of Chapter 6 see here.

For a review of Chapter 7 see here.

For a review of Chapter 8 see here.

For a review of Chapter 9 see here.

For a review of Chapter 10 see here.

For a review of Chapter 11 see here.

For a review of Chapter 12 see here.

In Support of Method – Critique of Feyerebend’s ‘Against Method’ see here.

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail justinmarley17@yahoo.co.uk. Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.