Month: September 2022

CROSS WIRED. “Predicting this finding of “cross-activation” between grapheme and color regions, Ramachandran and Hubbard proposed that synesthesia results from an excess of neural connections between associated modalities, possibly due to decreased neural pruning between (typically adjacent) regions that are interconnected in the fetus.” https://lnkd.in/dfc7eju View in LinkedIn

BRAIN DIFFERENCES. “Consistent with this suggestion, a number of studies have demonstrated anatomical differences in the inferior temporal lobe near regions related to grapheme and color processing in synesthetes, including increased fractional anisotropy (reflecting increased white matter or coherence of white matter), and increased gray matter volume; increased connectivity has been found in other forms of synesthesia as well.” https://lnkd.in/dfc7eju View in LinkedIn

ELECTRIC CONNECTIONS. “Furthermore, Brang and colleagues recently demonstrated that color area V4 becomes active as early as 110 ms after viewing achromatic letters and numbers, signifying that synesthetic colors follow a similar time-course in the brain as colors evoked from the retina.” https://lnkd.in/dfc7eju View in LinkedIn

BOTTOM-UP. “The same number can take on multiple colors in some synesthetes...or even the visual appearance of textural qualities like metallic and smooth, further suggesting that synesthesia is a bottom-up sensory phenomenon.” https://lnkd.in/dfc7eju View in LinkedIn

TOP DOWN. “Nevertheless, top-down influences (e.g., attention, context, etc.) must also play a significant role in synesthesia as first shown by Ramachandran and Hubbard using Navon figures; that is, if the subject sees a large 5 made up of small 2 s, the evoked color will change depending on whether the subject focuses on the local or global image (i.e., the “trees” or “forest”).” https://lnkd.in/dfc7eju View in LinkedIn

FAMILIAL TRAIT. “While a proven genetic basis for synesthesia remains elusive, the phenomenon tends to run in families, as ∼40% of synesthetes report a first-degree relative with the condition.” https://lnkd.in/dfc7eju View in LinkedIn

HUGE VARIATION. “At least 60 different forms of synesthesia have been documented (i.e., different combinations among the senses), reflecting the extreme heterogeneity of the condition, and one could easily assume that each type of synesthesia is caused by a unique gene or set of genes.” https://lnkd.in/dfc7eju View in LinkedIn

PROPENSITY TO LINK. “However, the specific form of synesthesia an individual expresses can vary within families, suggesting the genetic undertones impose a predisposition to synesthesia but not its expression. Indeed, individuals with one type of synesthesia are much more likely to have another as well, an observation that was adduced by Ramachandran and Hubbard as support for the idea that the defective pruning gene or genes confer a general propensity to linking unrelated sensations or even concepts.” https://lnkd.in/dfc7eju View in LinkedIn

CLUSTERING. “Further, while individual synesthetes often display multiple forms of the phenomenon, large-scale factor analyses suggest that some variants co-occur with greater frequency within a single individual, suggesting that some forms are more highly related (i.e., local “clustering” or “islands” of synesthesia types), which is suggestive of a common origin.” https://lnkd.in/dfc7eju View in LinkedIn

NON CLUSTERING. “However, non-clustering forms still co-occur with greater frequency than predicted by prevalence rates in the general population, significantly impeding theories of single genetic markers and the notion of independence among different forms of the condition.” https://lnkd.in/dfc7eju View in LinkedIn