The N400 in silico: A review of computational models

Predictive Coding explains the dynamics of neural activity within the left ventromedial temporal lobe during reading comprehension

“…Similar to predictive coding, IAC architectures allow for an unrestricted top-down ow of information across multiple, hierarchically-organized levels of representation, which could pre-activate lower-level lexico-semantic representations that are subsequently con rmed by expected inputs. If one further assumes that these expected inputs induce a smaller shift in state at the lexico-semantic level than unexpected inputs, this type of architecture could also explain why, in the present study, the ventromedial temporal lobe both reinstated prior lexico-semantic predictions to expected input, and generated a larger univariate response to unexpected inputs (although we note that, unlike predictive coding, this does not explain how the brain computes this change in state, or why such a change in state would result in a smaller evoked response 24,25 ).…”

The P600 as a continuous index of integration effort

“…This update is what RI theory calls integration and attributes to the P600. manipulations but naturally extends to those semantic P600 findings induced not only by semantic and pragmatic factors (Burkhardt, 2006(Burkhardt, , 2007Cohn & Kutas, 2015;Delogu et al, 2019;Dimitrova et al, 2012;Hoeks et al, 2013;Regel et al, 2010;Schumacher, 2011;Spotorno et al, 2013;Xu & Zhou, 2016) but also those induced by manipulations of syntax (Gouvea et al, 2010;see Brouwer et al, 2012;Delogu et al, 2019 for discussion) and syntax-driven semantic composition (Fritz & Baggio, 2020, 2022. Importantly, on the RI account, the amplitude of the P600 should not be a binary response to violating stimuli but should rather be sensitive to integration effort on a continuous scale (Brouwer et al, 2012), reflecting comprehension-centric surprisal (Brouwer et al, 2021).…”

“…It is still under debate, however, which of these two components indexes semantic integration—the core operation of compositionally updating an unfolding utterance meaning representation with incoming information—during online language comprehension. Traditionally, semantic integration has been attributed to the N400 component (Brown & Hagoort, 1993, 2000; Hagoort et al, 2004), such that its amplitude is continuously related to integration effort, a mapping that underpins several contemporary neurocomputational models of comprehension (for a review see Eddine et al, 2022). The P600 has traditionally been discussed in relation to syntactic and structural processing (Hagoort et al, 1993; Osterhout & Holcomb, 1992).…”

Visual Verbal Information Processing under Conditions of Reading and Categorization in Schizotypy: An Event-Related Brain Potential Study

“…An enlarged N400 amplitude in response to non-target stimuli is consistent with previous studies [26,27] which reported an increased amplitude of this component in re- sponse to the task-irrelevant stimuli. It is known that topdown processes may elicit less N400 activity [23] and the processing of task-relevant stimuli might be facilitated by increasing the "gain" of neurons in brain areas which process task-relevant stimulus information, while decreasing the gain of neurons in other areas and blocking the processing of task-irrelevant information [15]. Results reported for the low-SPQ group may be considered in line with this framework and demonstrate facilitation by top-down influence of the current goal in case of task-relevant stimuli.…”

“…This anomaly is thought to reflect a less than normal inhibition or greater than normal activation of unrelated information during semantic processing [18]. However, it is known that the N400 component is modulated not only by lexical and semantic features but also is sensitive to bottom-up and top-down processes during semantic operations [23]. One factor that allows modulation of the top-down and bottom-up control of information processing is a variation of the task conditions performed by the participants.…”