Is autism really a form of synesthesia?

I would just as soon throw out the DSM and just use neural wiring as the basis for categorization of psychiatric conditions .  To me, it is clear that psychiatric phenotypes can be categorized on the basis of column A white matter wiring, column B gray matter volume, and column C genes/chemicals/other local environmental conditions.

In a way, where neural connections define the person, everyone is sort of a synesthete.

Synesthesia is one of the more highly publicized conditions where neural cross-talk results in “cross-sensory percepts; an involuntary association of, say,  colors to letters, or smells to sounds. (I’m always a bit wistful in reading about the magic lands of the synesthetes, where sounds taste like chocolate, and numbers can be girlish).

The hallmark of synesthesia is that the sensory percepts have a connection that is involuntary and consistent.  Moreover, the connections are based on information already acquired: there is no delusion or confabulation. Circuits are connected to existing sockets of neurally-encoded information.

Using this framework, mis-fired wiring explains a lot. Take spouse abusers. Please.  (Sorry).

I wondered about spouse abusers because their wires seem to specifically cross “person who loves me” with “red alert threat.” (See, “Wife batterers: A synesthesia subtype for domestic violence perpetrators?” ).

Now for autism. A new report details observations that high functioning autistic spectrum folks who have savant-like talents may be hyper-perceptive — they may have superhuman powers to sense things.   But, not all things — just certain things. Perhaps this hyper-perception is really a hyper-wiring connection: like synesthetes.

Some kind of superhuman skill would seem plausible with certain autistic spectrum type folks who have savant-skills.  Like, the 17 year old boy diagnosed with Aspergers who came extremely close to having others set up an airline for him. This is after plans fell through for booking the US tour group of  “High School” musical (the money snag, bummer).  You have to have a really good perception-system, systematizing brain, and really REALLY good memory.  (Report from the London Times).

Another report on a “superior memorist” looks a lot to me like synesthesia connecting numbers and specific emotions. (Raz et al., “A slice of pi : An exploratory neuroimaging study of digit encoding and retrieval in a superior memorist, “ Neurocase. 2009 Jul 6:1-12; HT: NotoriousLTP at Neurotopia) The memorist could recite over 500 digits in pi, but was poor in remembering neutral faces and common events.  The individual explained his way of memorizing involved emotionally charged associations.  This sounds to me like a bit of Asperger’s (in that the person was not good with faces), along with the kind of synesthesia where numbers (graphenes) are associated with emotions or spatial locations.

There is another case of an individual mathematical savant with Asperger’s and number-synesthesia:

Single case: DT is a savant with exceptional abilities in numerical memory and mathematical calculations. DT also has an elaborate form of synaesthesia for visually presented digits. Further more, DT also has Asperger syndrome (AS). We carried out two preliminary investigations to establish whether these conditions may contribute to his savant abilities. Neuroimaging: In an fMRI digit span study, DT showed hyperactivity in lateral prefrontal cortex when encoding digits, compared with controls. In addition, while controls showed raised lateral prefrontal activation in response to structured (compared to unstructured) sequences of digits, DT’s neural activity did not differ between these two conditions. In addition, controls showed a significant performance advantage for structured, compared with unstructured sequences whereas no such pattern was found for DT. We suggest that this performance pattern reflects that DT focuses less on external mathematical structure, since for him all digit sequences have internal structure linked to his synaesthesia. Finally, DT did not activate extra-striate regions normally associated with synaesthesia, suggesting that he has an unusual and more abstract and conceptual form of synaesthesia. This appears to generate structured, highly-chunked content that enhances encoding of digits and aids both recall and calculation. Neuropsychology: People with AS preferentially attend to local features of stimuli. To test this in DT, we administered the Navon task. Relative to controls, DT was faster at finding a target at the local level, and was less distracted by interference from the global level. Discussion: The propensity to focus on local detail, in concert with a form of synaesthesia that provides structure to all digits, may account for DT’s exceptional numerical memory and calculation ability. This neural and cognitive pattern needs to be tested in a series of similar cases, and with more constrained control groups, to confirm the significance of this association.

Raz A, Packard MG,Alexander GM,Buhle JTZhu H,Yu S, Peterson BS. “A slice of pi : An exploratory neuroimaging study of digit encoding and retrieval in a superior memorist, “Neurocase. 2009 Jul 6:1-12

Bor D, Billington J, Baron-Cohen S., “Savant Memory for Digits in a Case of Synaesthesia and Asperger Syndrome is Related to Hyperactivity in the Lateral Prefrontal Cortex,” Neurocase. 2007 Oct;13(5):311-9

Baron-Cohen S, Ashwin E, Ashwin C, Tavassoli T, Chakrabarti B., “Talent in autism: hyper-systemizing, hyper-attention to detail and sensory hypersensitivity,”  Philos Trans R Soc Lond B Biol Sci. 2009 May 27;364(1522):1377-83. 10.1098/rstb.2008.0337 Phil. Trans. R. Soc. B 27 May 2009 vol. 364 no. 1522 1377-1383.