The cerebral processes which support word reading may be analyzed into two stages. The first stage takes place within the visual system, and allows for the invariant identification of letters and their order. This process involves sequentially low-level visual areas and the so-called visual word form area (VWFA), located in the lateral occipitotemporal sulcus (Cohen et al., 2000). During the second word processing stage, orthographic information is transferred to language areas, where it will allow the reader to access sound and meaning representations. Pure alexia, or alexia without agraphia, which was perfectly described by Dejerine (1892, 1895), consists in a selective impairment of reading resulting from the disruption or the deafferentation of the VWFA. However, the pathophysiological account put forward by Dejerine was somewhat different from the currently prevailing explanation (Figure 1).

During reading, the left occipital cortex (yellow) receives input from the left lateral geniculate through the optic radiations [1Cohen L., Dehaene S., Naccache L., Lehericy S., Dehaene-Lambertz G., Henaff M.A., et al. The visual word form area: spatial and temporal characterization of an initial stage of reading in normal subjects and posterior split-brain patients Brain 2000 ;  123 : 291-307 [cross-ref]

Cliquez ici pour aller à la section Références], from the opposite hemisphere through callosal fibers [2Dejerine J. Contribution à l’étude anatomo-pathologique et clinique des différentes variétés de cécité verbale Mem Soc Biol 1892 ;  4 : 61-90

Cliquez ici pour aller à la section Références], and it projects to later stations in the reading network. Dejerine proposed that the target of such projections was the angular gyrus, although the corresponding fiber tract was purely hypothetical [3Dejerine J. Anatomie des centres nerveux  Paris: Rueff et Cie (1895). 

Cliquez ici pour aller à la section Références]. According to the current data, the target of occipital projections is actually the VWFA (red), which is reached through the ILF (3′), which was disrupted in the patient reported in Epelbaum et al. (2008) [4Epelbaum S., Pinel P., Gaillard R., Delmaire C., Perrin M., Dupont S., et al. Pure alexia as a disconnection syndrome: new diffusion imaging evidence for an old concept Cortex 2008 ;  44 : 962-974 [cross-ref]

Cliquez ici pour aller à la section Références], as it was in Dejerine's patient.