Autism and Minicolumns

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Minicolumns are very interesting we must learn more about them however I would like to raise this question could minicolumns be the reason why autistic people are more likely to have Synesthesia or seizures or both?

These attributes come at a potential cost. The reduction in width is a result of a reduction in the minicolumn’s peripheral zone of inhibitory and disinhibitory activity. The inhibitory fibers act to keep stimuli within individual minicolumns, and the reduction in this space increases the chance of stimuli overflowing to adjacent minicolumns, providing an amplifier effect and potential hypersensitivity. Narrower minicolumns may also result in an increased number of minicolumns per macrocolumn, which can also result in an amplification of thalamic input, and as each minicolumn’s response to thalamic input is modulated by the activity of neighbouring columns, a reduction in GABAergic inhibitory activity could also result in a loss of inhibition and greater amplification. Stimuli ‘spill’ and greater amplification could result in the increased incidence of seizures in autistics.

Scientific genius

ONE of the greatest scientific minds of all time ended up in 240 pieces, packed into a couple of jars, and was carted around for years in the trunk of Princeton pathologist Harvey Thomas's car. Einstein's brain, at the time of his autopsy in 1955 (just 7 hours after his death), was reported by Thomas to appear unremarkable - it was a little shrunken with age, and slightly smaller than average. Nevertheless, Thomas carefully photographed and dissected it, and kept it preserved in formalin until science had new ways to scrutinise this amazing grey matter.

In the early 1980s, neurologist Marian Diamond from the University of California, Berkeley, analysed some slides containing sections of Einstein's brain taken from the prefrontal and parietal lobes. These areas are part of the "association" cortex, which is involved with higher thought. Comparing the slides with similar tissue from 11 control brains, she found that Einstein's brain contained a greater than normal ratio of glial cells to neurons. Glial cells were until recently thought to be support cells for the neurons, important in providing energy and resources but not much more. They are now known to be involved in neural processing and signal transmission too. The absolute numbers were hard to measure, because of the way the tissue was preserved and sectioned, but Einstein's brain appeared to have double the normal number of glial cells in the left parietal region.

Diamond compared her findings to a case report of a mathematician whose brain was damaged in this same region so that he became unable to draw or write formulae, or to use a slide rule. Some eminent mathematicians say abstract concepts feel almost real, to the point that it is as if they exist in the brain and can be manipulated like real objects. Perhaps this region, which is known to be important for visuospatial cognition, is key. There are other possibilities, however. Einstein claimed to be dyslexic and to have a poor memory for words. Damage to this region can cause dyslexia, so maybe his low neuron-to-glia ratio was a cause or result of his verbal difficulties rather than his reasoning skills.

Another study in the mid-1990s looked at the outer millimetre of cortical tissue from Einstein's right prefrontal lobe, a region that is associated with working memory, planning, regulation of intellectual function, and motor coordination. Britt Anderson from the University of Alabama, Birmingham, reported that the number and size of neurons here appeared normal, but that the cortex was thinner than average (2.1 millimetres compared with 2.6 millimetres in five control brains) making Einstein's cortical neurons more densely packed than usual. Anderson speculates that closer packing may speed up communication between neurons.

Then in 1998, Witelson studied Einstein's brain again, this time from photos, and it appeared unremarkable except for the parietal lobes. Here the brain was 15 per cent wider than average, giving it a more spherical shape. In addition, two major grooves in this area were joined into one large furrow, which suggests the local circuitry was particularly highly integrated, Witelson speculates. What's more, while normal brains are asymmetrical, Einstein's parietal lobes were symmetrical. This all lends weight to the idea that his brain structure may have been unusual in some key areas that are important for spatial and reasoning skills.
Einstein's brain was 15 per cent wider than average, making it more spherical

What about other scientists? Manuel Casanova from the University of Louisville, Kentucky, studied post-mortem brain tissue from three eminent scientists and found that there were interesting patterns in the arrangement of cortical neurons (Autism, vol 11, p 557). The smallest processing module of neurons in the cortex is called a minicolumn - a vertical arrangement of cells that seem to work as a team. The scientists' minicolumns were smaller than those of controls, with less space between cells, meaning there were more processing units within any given cortical area. Computer modelling suggests that smaller processing units may allow for better signal detection and more focused attention. Small minicolumns are also seen in people with autism and Asperger's syndrome, says Casanova.