Differential Phonological and Semantic Modulation of Neurophysiological Responses to Visual Word Recognition

Abstract

Background: Reading words for meaning relies on orthographic, phonological and semantic processing. The triangle model implicates a direct orthography-to-semantics pathway and a phonologically mediated orthography-to-semantics pathway, which interact with each other. The temporal evolution of processing in these routes is not well understood, although theoretical evidence predicts early phonological processing followed by interactive phonological and semantic processing. Method: This study used electroencephalography-event-related potential (ERP) analysis and magnetoencephalography (MEG) source localisation to identify temporal markers and the corresponding neural generators of these processes in early (∼200 ms) and late (∼400 ms) neurophysiological responses to visual words, pseudowords and consonant strings. Results: ERP showed an effect of phonology but not semantics in both time windows, although at ∼400 ms there was an effect of stimulus familiarity. Phonological processing at ~200 ms was localised to the left occipitotemporal cortex and the inferior frontal gyrus. At 400 ms, there was continued phonological processing in the inferior frontal gyrus and additional semantic processing in the anterior temporal cortex. There was also an area in the left temporoparietal junction which was implicated in both phonological and semantic processing. In ERP, the semantic response at ∼400 ms appeared to be masked by concurrent processes relating to familiarity, while MEG successfully differentiated these processes. Discussion: The results support the prediction of early phonological processing followed by an interaction of phonological and semantic processing during word recognition. Neuroanatomical loci of these processes are consistent with previous neuropsychological and functional magnetic resonance imaging studies. The results also have implications for the classical interpretation of N400-like responses as markers for semantic processing.

How Does iReadMore Therapy Change the Reading Network of Patients with Central Alexia?

“…Therapy effects in patients with PA are likely to rely on improving feedback support from the intact phonological and semantic representation of words within their left IFG as damage affects input to the reading network. Increased IFG involvement has been identified for tasks demanding subordinate levels of semantic knowledge (Nagel et al, 2008;Whitney et al, 2011) and tasks relating to phonology (Devlin et al, 2003;Drakesmith et al, 2015). By contrast, patients with CA have damage to the central phonological and/or semantic representations (Crisp and Lambon Ralph, 2006;Robson et al, 2012;Hoffman et al, 2015) or connections to them.…”

Examining the relationship between home literacy environment and neural correlates of phonological processing in beginning readers with and without a familial risk for dyslexia: an fMRI study

“…Semantic processing supports comprehension of the meaning of words, while phonological processing is important in the decoding of words (Horowitz-Kraus et al 2013; Pugh et al 2013; Chistopher J Lonigan et al 2000; Adams 1990). Separate neuroanatomical networks of phonological and semantic processing have also been described (Binder et al 2009; Drakesmith et al 2015; Raschle et al 2012; Schlaggar and McCandliss 2007; Pugh et al 2001). It is therefore not surprising that activation of unique brain regions was observed during these distinctive reading-related tasks.…”

Altered dynamic functional connectivity of auditory cortex and medial geniculate nucleus in first-episode, drug-naïve schizophrenia patients with and without auditory verbal hallucinations

“…Our data revealed that aberrant occipital-temporal and occipital-MGN dynamic FC may be associated with the mechanism of AVH in schizophrenia patients. More and more studies observed that the occipital lobe is associated with phonological and semantic modulation ( 61 , 62 ), thus we speculate that abnormal conduction between the occipital lobe and auditory pathway may lead to aberrant phonological or semantic processing, which may lead to AVH in schizophrenia patients. Moreover, a “multisensory interplay” theory ( 63 , 64 ) may be another corroboration of our results, Lewis et al also reported that audio visual synchronization combines dynamic visual and aural inputs to create a more powerful and dependable multiple sensory system ( 65 ).…”