An fMRI study of sentence-embedded lexical-semantic decision in children and adults

Abstract

Lexical-semantic knowledge is a core language component that undergoes prolonged development throughout childhood and is therefore highly amenable to developmental studies. Most previous lexical-semantic functional MRI (fMRI) studies have been limited to single-word or word-pair tasks, outside a sentence context. Our objective was to investigate the development of lexical-semantic language networks in typically developing children using a more ecological sentence-embedded semantic task that permitted performance monitoring while minimizing head movement by avoiding overt speech. Sixteen adults and 23 children completed two fMRI runs of an auditory lexical-semantic decision task with a button-press response, using reverse speech as control condition. Children and adults showed similar activation in bilateral temporal and left inferior frontal regions. Greater activation in adults than in children was seen in left inferior parietal, premotor, and inferior frontal regions, and in bilateral supplementary motor area (SMA). Specifically for semantically incongruous sentences, adults also showed greater activation than children in left inferior frontal cortex, possibly related to enhanced top-down control. Age-dependent activation increases in motor-related regions were shown to be unrelated to overt motor responses, but could be associated with covert speech accompanying semantic decision. Unlike previous studies, age-dependent differences were not detected in posterior sensory cortices (such as extrastriate cortex), nor in middle temporal gyrus.

The role of the supplementary motor area for speech and language processing

“…In this study, the semantic processing aspect of pre-SMA seems to be independent of any motor effects. Similarly, SMA activation (here not differentiated between pre-SMA and SMA proper) was reported in a lexical-semantic decision study in adults as well as in children (7-10 years), and also here simple motor effects could largely be excluded (Moore-Parks et al, 2010). A further study was performed using the production of words and pseudowords as experimental task conditions (Hartwigsen et al, 2013a).…”

Neurophysiological preconditions of syntax acquisition

“…There is now accumulating evidence that the superior temporal and inferior frontal areas are activated during sentence processing during early childhood (Brauer & Friederici, 2007;Moore-Parks et al, 2010;Yeatman et al, 2010;Dick et al, 2010). The neurophysiological basis of the interplay between these regions at the diVerent developmental stages is yet to be determined.…”

Evaluating reverse speech as a control task with language-related gamma activity on electrocorticography

“…Previous fMRI studies report that forward speech induces stronger BOLD responses in bilateral superior temporal regions compared to reverse speech (Moore-Parks et al, 2010; Redcay et al, 2008; Redcay and Courchesne, 2008). This phenomenon has been observed across a wide age range, including children.…”

“…The literature from functional studies points to a commonly used reverse speech control task (Gherri and Eimer, 2011; Moore-Parks et al, 2010; Perani et al, 1996; Redcay et al, 2008; Redcay and Courchesne, 2008; Sato et al, 2011). Generally, a reverse speech control task is a replica of the primary forward speech task that has been reversed in time.…”