Abstract
Discourse is a commonly occurring and cognitively demanding form of naturalistic communication (e.g., conversation, event narration, personal and fictional narratives, text reading/generation). Because of the prevalence of these communication acts in daily routines (e.g., educational, vocational, and social), disrupted discourse is an important target for treatment of persons with cognitive-communication (CC) disorders (American Speech-Language Hearing Association, 2005). However, there is a paucity of information with regard to the underlying cognitive architecture and processing demands associated with the various forms of discourse in non-brain-injured adults. This is, in part, due to a number of methodological constraints of functional neuroimaging technologies such as functional magnetic resonance imaging that severely limit ecologically typical communication acts such as listening and speaking during scanning. To circumvent these issues, this pilot investigation used functional near infrared spectroscopy (fNIRS) to monitor hemodynamic activity in the prefrontal cortex (PFC) during natural discourse-processing tasks in 13 neurologically healthy adult participants. Task demands were manipulated across a variety of discourse types to elucidate the associated neural and cognitive resources. Results indicate that the comprehension of well-organized discourse text is minimally demanding on the PFC. However, discourse production places a significant burden on the PFC and these processing demands generally reflect the relative complexity of the discourse task. These findings are discussed in terms of potential clinically relevant implications with regard to the elicitation, assessment, and remediation of CC impairments in clinical populations.