Seminar Series

What does the brain know about orthography?

The word “orthography” comes form the Greek roots orthós (correct) and gráphein (to write) and refers to the visual codes that represent a particular language. By definition, these representations are specific to written language and consequently, in models of reading, orthography constitutes the input to the system. To what extent, though, is orthography reified in the brain? One possibility is that the “visual word form area” located in the ventral occipito-temporal cortex (vOT) contains orthographic engrams in the form of either lexical or pre-lexical representations. Alternately, vOT may integrate visuospatial features abstracted from visual inputs with higher level associations such as the sound and meaning of the stimulus. By this account, specialization for orthography emerges from regional interactions without assuming that vOT is selectively tuned to orthographic features. In this talk, I will present functional neuroimaging and transcranial magnetic stimulation studies that test orthographic engram hypotheses and demonstrate that both pre-lexical and lexical accounts are incompatible with the neurophysiological evidence. In addition, the findings call into question the notion that a single brain region is sufficient to represent orthographic information and thus acts as the input to the reading system. I then consider a predictive coding account of vOT functioning that explains a wide range of data from both reading and non-reading studies. I conclude that orthography per se does not exist at the neuronal level but rather is best considered a useful functional abstraction.