Structural studies from Michael Casanova and colleagues showed that the brains of dyslexic and autistic subjects had opposite findings. Microcolumns are repeating groups of neurons that share a common dendritic bundle. The microcolumnar hypothesis is the idea that the microcolumn is the basic unit in the cortex, not individual neurons.
"Dyslexia and autism are on opposite tails of the normal distribution of the width of minicolumns...Autistic individuals have increased number of smaller minicolumns and dyslexic children have decreased number of larger minicolumns..." When the depth of gyral depths were measured of dyslexics compared to controls, "mean gyral white matter depth was 3.05 mm (SD ± 0.30 mm) in dyslexic subjects and 1.63 mm (SD ± 0.15 mm) in the controls." Researchers speculated that longer connectivity in the brains of dyslexics could account for "a greater capacity for abstract, 'visionary' thinking", but also slower development (late blooming?) including a slower development of reading. Its information like this that should reinforce the idea that dyslexic children should have a differentiated educational program (fewer inappropriate demands at early ages) - and recognition of high creative potential and capacity for abstraction.
The changes in autism could also account for why some people with autism show extreme precocity with rote tasks, may have unusual gifts of rapid mathematical calculation, and superior abilities with certain tasks of visual discrimination (like Oliver Sack's account of two twins with autism who could rapid determine when 111 matches had fallen to the ground).
Structural differences between dyslexic and autistic brains
Increased gyral depth in dyslexia (abstract only)
Savant numerosity pdf