Neural systems underlying lexical competition: an eye tracking and fMRI study

Area of Science:

• Neuroscience
• Psycholinguistics
• Cognitive Science

Background:

• Understanding word recognition involves exploring how the brain processes competing word forms.
• Phonological onset competition, where words share initial sounds, is a key aspect of this process.
• Previous research suggests involvement of frontal and posterior brain regions, but precise roles require further investigation.

Purpose of the Study:

• To investigate the neural mechanisms underlying phonological onset competition.
• To determine the specific brain regions involved in processing words with similar beginnings.
• To differentiate the roles of the left inferior frontal gyrus (IFG) and supramarginal gyrus (SMG) in lexical competition.

Main Methods:

• Utilized a combination of eye tracking and functional magnetic resonance imaging (fMRI).
• Presented participants with auditory targets and visual stimuli including targets, onset competitors, and unrelated items.
• Analyzed behavioral data (eye movements) and neural activation patterns.

Main Results:

• Behavioral data confirmed increased visual attention towards onset competitors.
• fMRI revealed activation in distinct clusters within the left IFG (BA 44 and BA 45) and the left SMG extending into the posterior superior temporal gyrus.
• These activations were specifically linked to trials with phonological competition.

Conclusions:

• The left IFG is sensitive to phonological similarity-driven competition, not solely semantic factors.
• The SMG is involved in accessing lexical form and also in accessing conceptual word representations.
• These findings elucidate the neural architecture supporting spoken word recognition and lexical selection.