01.19.10
Uta Frith: “Autism and Theory of Mind” (Talk)
01.12.10
Why Do Pigeons Walk With Bobbing Heads?
Have you noticed how pigeons (and other birds) bob their heads while walking? Ever wondered why?
No, there’s no connection between their heads and their legs forcing them to move their head as they walk. It doesn’t have to do with balance either, as it was shown in Frost’s 1978 study. In this experiment pigeons were trained to walk on a treadmill (I can’t imagine how they did that..). The researchers showed that head-bobbing is abolished when pigeons walk on a treadmill. This “suggests (that) it is primarily a visual response rather than an equilibratory response”.
Here are some links, if you’re interested in learning more about head-bobbing in pigeons (and other birds):
the original study by Frost (pdf)
Head-bobbing of walking birds (a review)
Vision during head bobbing (pdf – recent study by Ortega et al)
…and finally: head-bobbing of a walking hen. What happens when it’s being carried? Is it relevant to Frost’s study? What do you think?
.
01.07.10
A Few Calls a Day Keep Alzheimer’s Away?
Do you remember all those reports trying to find a connection between cellphones and unpleasant things, like cancer, ear aches, etc? Worry not!? Now thanks to researchers from the University of South Florida you can embrace your newly purchased Nexus One without worrying about possible side-effects.
After long-term exposure to electromagnetic waves such as those used in cell phones, mice genetically altered to develop <a href=”“>Alzheimer’s performed as well on memory and thinking skill tests as healthy mice, the researchers wrote in the Journal of Alzheimer’s Disease.
The results were a major surprise and open the possibility of developing a noninvasive, drug-free treatment for Alzheimer’s, said lead author Gary Arendash of the University of South Florida.
He said he had expected cell phone exposure to increase the effects of dementia.
“Quite to the contrary, those mice were protected if the cell phone exposure was stared in early adulthood. Or if the cellphone exposure was started after they were already memory- impaired, it reversed that impairment,” Arendash said in a telephone interview.
Arendash’s team exposed the mice to electromagnetic waves equivalent to those emitted by a cellphone pressed against a human head for two hours daily over seven to nine months.
At the end of that time, they found cellphone exposure erased a build-up of beta amyloid, a protein that serves as a hallmark of Alzheimer’s disease.
The Alzheimer’s mice showed improvement and had reversal of their brain pathology, he said.
“It (the electromagnetic wave) prevents the aggregation of that bad protein of the brain,” Arendash said. “The findings are intriguing to us because they open up a whole new field in neuroscience, we believe, which is the long-term effects of electromagnetic fields on memory.”
Arendash said his team was modifying the experiment to see if they could produce faster results and begin testing humans.
Despite decades of research, there are few effective treatments and no cure for Alzheimer’s, the most common form of dementia. Many treatments that have shown promise in mice have had little effect on humans.
More than 35 million people globally will suffer from Alzheimer’s disease or other forms of dementia in 2010, according to the Alzheimer’s Association.
There has been recent controversy about whether electromagnetic waves from cellphones cause brain cancer.
Co-author Chuanhai Cao said the mice study is more evidence that long-term cellphone use is not harmful to the brain.
Groups such as the World Health Organization, the American Cancer Society, and the National Institutes of Health, have all concluded that scientific evidence to date does not support any adverse health effects associated with the use of cellphones.
(Editing by Alan Elsner)
I wouldn’t recommend spending too many hours on the phone, though, as the long-term effects are not known yet. I’m really curious to see if other studies will replicate these results in humans. Imagine how fierce the competition between Google and Apple will be then!
01.03.10
Why Are Women More Sensitive To Touch Than Men?
Women are more sensitive to touch than men, but not because of their gender, according to Peter and his colleagues of McMaster University in Toronto, Canada. It seems that this observed difference is not an effect of age, but an effect of size.
Here’s the abstract of the study:
We have observed that passive tactile spatial acuity, the ability to resolve the spatial structure of surfaces pressed upon the skin, differs subtly but consistently between the sexes, with women able to perceive finer surface detail than men. Eschewing complex central explanations, we hypothesized that this sex difference in somatosensory perception might result from simple physical differences between the fingers of women and men. To investigate, we tested 50 women and 50 men on a tactile grating orientation task and measured the surface area of the participants’ index fingertips. In subsets of participants, we additionally measured finger skin compliance and optically imaged the fingerprint microstructure to count sweat pores. We show here that tactile perception improves with decreasing finger size, and that this correlation fully explains the better perception of women, who on average have smaller fingers than men. Indeed, when sex and finger size are both considered in statistical analyses, only finger size predicts tactile acuity. Thus, a man and a woman with fingers of equal size will, on average, enjoy equal tactile acuity. We further show that sweat pores, and presumably the Merkel receptors beneath them, are packed more densely in smaller fingers.
Link to the original study.
12.25.09
Goodbye Rain Man
Kim Peek , the man who inspired Dustin Hoffman’s well known character in the film Rain Man , died a few days (19/12) ago of heart attack at the age of 58.
Peek was not able to live on his own and depended on his father for most everyday activities. However, he was known for his extraordinary memory, mathematical and reading skills. Even though, Peek was though to be autistic, scans performed in 2008 revealed that the most likely diagnosis was FG syndrome .
Here are a few links about the famous savant:
- videos of Kim Peek .
- Scientific American’s article: Inside the Mind of a Savant
- Kim Peek – The Real Rain Man (Wisconsin Medical Society entry)
- Kim Peek has left the buliding (Mind Hacks)
12.01.09
Sleep and Brain Connectivity
Massimini et al. (2005) attempted to study sleep and cortical connectivity by combining two different methods, TMS and EEG.
The abstract is below:
“When we fall asleep, consciousness fades yet the brain remains active. Why is this so? To investigate whether changes in cortical information transmission
play a role, we used transcranial magnetic stimulation together with highdensity electroencephalography and asked how the activation of one cortical area (the premotor area) is transmitted to the rest of the brain. During quiet
wakefulness, an initial response (È15 milliseconds) at the stimulation site was followed by a sequence of waves that moved to connected cortical areas several centimeters away. During non–rapid eye movement sleep, the initial
response was stronger but was rapidly extinguished and did not propagate beyond the stimulation site. Thus, the fading of consciousness during certain
stages of sleep may be related to a breakdown in cortical effective connectivity.”
Read the original study here (pdf).
11.26.09
Project H.M. & Clive Wearing’s Diaries
Project H.M.
H.M. is considered to be one of the most famous cases in neuropsychology. His dense amnesia contributed significantly to our understanding of human memory. On December 2nd, exactly a year after his death, anyone interested will have the chance to watch the dissection of his brain. I’m really looking forward to this (that sounds a bit weird).
According to the Project H.M. official blog:
“On December 2nd, 2009 we will begin slicing the brain of the amnesic patient H.M. into giant histological sections. The brain specimen is going to be frozen and sectioned whole during one continuous session that we expect will last approximately 30 hours”
If you’re interested in finding more about the project and the next phase, visit the Project H.M. website
Clive Wearin’s Diaries @ Wellcome Trust Exhibition
A few months ago I wrote a post on Clive Wearing, another case of amnesia. If you’re lucky enough to live in London, you’d be interested to know that the Wellcome Trust’s new collection, titled “Identity: Eight Rooms, Nine Lives” hosts Wearing’s famous diaries in the Samuel Pepy’s room. The exhibition will be on from today until April and it’s a part of The Identity Project (Pressure Drop could also be interesting). Oh, and it’s free. For more information visit the exhibition’s website. They have a special section on Clive Wearing including a number of interesting videos.
image: Salvador Dali’s – the disintegration of the persistence of memory
11.10.09
fMRI Limitations And Criticism
Fancy images, impressive results, but can we really trust the reports of the majority of the neuroimaging studies out there? Here’s a couple of papers discussing the limitations of fMRI that you can read, if you’re interested in learning more about this method:
1. a great review by Nikos K. Logothetis published in Nature a year ago. Here’s the abstract:
Here I give an overview of the current state of fMRI, and draw on neuroimaging and physiological data to present the current understanding of the haemodynamic signals and the constraints they impose on neuroimaging data interpretation. Functional magnetic resonance imaging (fMRI) is currently the mainstay of neuroimaging in cognitive neuroscience.
Advances in scanner technology, image acquisition protocols, experimental design, and analysis methods promise to push forward fMRI from mere cartography to the true study of brain organization. However, fundamental questions concerning the interpretation of fMRI data abound, as the conclusions drawn often ignore the actual limitations of the methodology.”
2. Professor D. Attwell questions the neural basis of functional brain imaging signals:
“The haemodynamic responses to neural activity that underlie the blood-oxygen-level-dependent (BOLD) signal used in functional magnetic resonance imaging (fMRI) of the brain are often assumed to be driven by energy use, particularly in presynaptic terminals or glia.However, recent work has suggested that most brain energy is used to power postsynaptic currents and action potentials rather than presynaptic or glial activity and, furthermore, that haemodynamic responses are driven by neurotransmitter-related signalling and not directly by the local energy needs of the brain. A firm understanding of the BOLD response will require investigation to be focussed on the neural signalling mechanisms controlling blood flow rather than on the locus of energy use.”
P.S: For an introduction to fMRI, visit fMRI 4 Newbies website.
11.06.09
Executive Functions in ASD
There are three key theories that attempt to explain the links between brain and behaviour in Autistic spectrum disorders (ASD): the Theory of Mind Deficit Hypothesis (for a review see Baron-Cohen, 2001), the Weak Central Coherence (Happé & Frith, 2006) and that of Executive Dysfunction (Hill, 2004).
Executive functions is an umbrella term for a number of cognitive and behavioural capacities such as planning, working memory, inhibition, mental flexibility, multitasking, initiation and monitoring of action (Gilbert & Burgess, 2008). Executive functions are usually impaired in patients with frontal lobe damage and in many neurodevelopmental disorders like ADHD, OCD, schizophrenia and ASD. These disorders are likely to involve deficits in the frontal lobes.
Autistic people seem to be impaired only in some tests of executive functions, especially those involving multitasking (“Six Element Test”, Hill & Bird, 2006), planning (“Tower of London”, Ozonoff et al, 1991) and Inhibition (“Go/No-Go task” , Ozonoff & Strayer, 1997). Deficits have also been shown in planning and abstract problem solving tasks (Hill & Bird, 2006). On other tests their performance is equal or superior to control groups (Minshew, Goldstein & Siegel, 1997). It’s worth noting that ASD individuals are mostly impaired in newer tests rather than classical tests of executive functions (Hill & Bird, 2006, Gilbert et al., 2008). These findings could be due to the heterogeneity of different tests of executive function (Gilbert et al., 2008).
Most of the tasks in which ASD individuals show deficits are thought to be mediated by the frontal lobes. A number of studies have identified several several cortical, subcortical abnormalities and functional differences (Kawakubo et al., 2009; Schmitz et al., 2005).
The theory of cortical underconnectivity posits a deficit in integration of information at the neural and cognitive levels (Just et al., 2006). Findings from neuroimaging studies such as the thinning of the corpus callosum and the reduced connectivity, especially with the frontal areas and also the fusiform face area in ASD people support the theory of underconnectivity (Hughes, 2007). Recently, increased activation in medial rostral prefrontal cortex (BA 10) during tasks of stimulus-oriented versus stimulus-independent attention has been found in people with ASD (Gilbert et al., 2008). Previous studies has shown the importance of rPFC in selection between stimulus-oriented and stimulus-independent thought (Gilbert, Frith & Burgess, 2005; Ramnani & Owen, 2004). On the same task the control group showed greater activity primarily in bilateral occipital cortex. According to Gilbert et al.:
“This suggests that the control group were able to modulate activity in early visual cortex according to the attentional demands of the task to a greater degree than the ASD group. The stimuli were matched between the two conditions, suggesting attentional modulation rather than an effect of stimulus-category. This finding is consistent with the suggestion of functional underconnectivity in ASD”
Further Readings
Happé, F., & Frith, U. (1996). The neuropsychology of autism.Brain, 19, 1377-1400.
White, S., O’Reilly, H., & Frith, U. (2009). Big heads, small details and autism. Neuropsychologia, 47(5), 1274-1281.
Mundy, P. (2003). The Neural Basis of Social Impairments in Autism: The Role of the Dorsal Medial-Frontal Cortex and Anterior Cingulate System. Journal of Child Psychology & Psychiatry, 44, 793-809
Happé, F., Booth, R., Charlton, R. & Hughes, C. (2006) Executive function deficits in Autism Spectrum Disorders and Attention-Deficit/Hyperactivity Disorder: Examining profiles across domains and ages. Brain and Cognition.
Baron-Cohen, S., & Swettenham, J. (1998) Theory of mind in autism: Its relationship to executive function and central coherence. In D.J. Cohen & F.R. Volkmar (Eds.), Handbook of autism and pervasive developmental disorders (2nd ed., pp. 880–893). New York: Wiley.
Maria P.
