Competitive mechanisms in sentence processing: Common and distinct production and reading comprehension networks linked to the prefrontal cortex

Abstract

Despite much interest in language production and comprehension mechanisms, little is known about the relationship between the two. Previous research suggests that linguistic knowledge is shared across these tasks and that the left inferior frontal gyrus (LIFG) may be commonly recruited. However, it remains unclear the extent to which production and comprehension share competition mechanisms. Here we investigate this issue and specifically examine competition in determining the event roles in a sentence (agent or affected participant). We used both behavioral and fMRI methods and compared the reading and production of high- and low-competition sentences, specifically targeting LIFG. We found that activity in pars opercularis (PO), independently identified by a competition-driven localizer, was modulated by competition in both tasks. Psychophysiological interaction analyses seeded in PO revealed task-specific networks: In comprehension, PO only interacted with the posterior temporal lobe, whereas in production, it interacted with a large network including hippocampal, posterior temporal, medial frontal and subcortical structures. Production and comprehension therefore recruit partially distinct functional networks but share competitive processes within fronto-temporal regions. We argue that these common regions store long-term linguistic associations and compute their higher-order contingencies, but competition in production ignites a larger neural network implementing planning, as required by task demands.

Are There Really Syntactic Complexity Effects in Sentence Production? A Reply to Scontras et al. (2015)

“…Cells C-D show that the animacy of what is being discussed is also crucial: When speakers are describing something inanimate like policy (cell C), the long-dependency object-extractions and the short-dependency subject-extractions are equally favored and have equal initiation latencies (Montag & MacDonald, 2014). Humphreys and Gennari (2014), holding dependency distance constant, found that both initiation latency and production errors varied with the animacy of the head of the clause (reporter vs. policy). The one lexical combination in Fig.…”

Similarity-based competition in relative clause production and comprehension

“…Nevertheless, it is possible that competitive mechanisms do not take place in a single brain region but rather take place across more complex brain networks, and information flow within the network may be partially shared across various tasks. Indeed, several studies suggest more than one brain region might be involved in competition resolution (Duncan, 2010;Fuster, 2001;Gennari, MacDonald, Postle, & Seidenberg, 2007;Humphreys & Gennari, 2014). Although more research is surely needed to understand the cognitive and neural processes instantiating competition resolution, the present results suggest possible competitive mechanisms shared across tasks and new avenues for further research.…”

“…Critically, when processing relative clauses, which increase processing load and engender competition, both production and comprehension show common prefrontal activity within Broca s area, in addition to task-specific regions (Humphreys & Gennari, 2014). Specifically, when comparing production and comprehension of relative clauses with the methods and materials used in Studies 1 and 2, semantic similarity was found to positively correlate with the activity within this region (Humphreys & Gennari, 2014;Humphreys, 2012).…”

“…Specifically, when comparing production and comprehension of relative clauses with the methods and materials used in Studies 1 and 2, semantic similarity was found to positively correlate with the activity within this region (Humphreys & Gennari, 2014;Humphreys, 2012). Together, these findings suggest that production and comprehension recruit shared neural resources, in particular when producing and comprehending relative clauses involving similarity-based competition.…”

“…This appeared necessary because production and comprehension do involve different processes such as word retrieval vs. recognition, or motor planning vs. sensory analysis. More recently, however, researchers have started to investigate relationships between these two processing systems and what they have in common (Bock, Dell, Chang, & Onishi, 2007;Chang, Dell, & Bock, 2006;Gennari & MacDonald, 2009;Humphreys & Gennari, 2014;MacDonald, 2013;Menenti, Gierhan, Segaert, & Hagoort, 2011;Pickering & Garrod, 2007). Chang et al (2006), for example, suggest that the learner s experience shapes production processes, and that learning and production share the same computational architecture and the abstract structural knowledge underlying these processes.…”