A Common Neural Substrate for Language Production and Verbal Working Memory

Abstract

Abstract■ Verbal working memory ( VWM), the ability to maintain and manipulate representations of speech sounds over short periods, is held by some influential models to be independent from the systems responsible for language production and comprehension [e.g., Baddeley, A. D. Working memory, thought, and action. New York, NY: Oxford University Press, 2007]. We explore the alternative hypothesis that maintenance in VWM is subserved by temporary activation of the language production system [Acheson, D. J., & MacDonald, M. C. Verbal working memory and language production: Common approaches to the serial ordering of verbal information. Psychological Bulletin, 135, 50-68, 2009b]. Specifically, we hypothesized that for stimuli lacking a semantic representation (e.g., nonwords such as mun), maintenance in VWM can be achieved by cycling information back and forth between the stages of phonological encoding and articulatory planning. First, fMRI was used to identify regions associated with two different stages of language production planning: the posterior superior temporal gyrus (pSTG) for phonological encoding (critical for VWM of nonwords) and the middle temporal gyrus (MTG) for lexical-semantic retrieval (not critical for VWM of nonwords). Next, in the same subjects, these regions were targeted with repetitive transcranial magnetic stimulation (rTMS) during language production and VWM task performance. Results showed that rTMS to the pSTG, but not the MTG, increased error rates on paced reading (a language production task) and on delayed serial recall of nonwords (a test of VWM). Performance on a lexical-semantic retrieval task (picture naming), in contrast, was significantly sensitive to rTMS of the MTG. Because rTMS was guided by language production-related activity, these results provide the first causal evidence that maintenance in VWM directly depends on the long-term representations and processes used in speech production. ■

tDCS to temporoparietal cortex during familiarisation enhances the subsequent phonological coherence of nonwords in immediate serial recall

“…These data accord well with theories that propose that the short-term phonological store draws on ongoing processing within the phonological system (Patterson et al, 1994;Acheson et al, 2011;Majerus, 2013). In the familiarisation phase, the phonological system was able to partially learn the phoneme sequences corresponding to familiar nonwords: this learning gave rise to pattern completion properties, allowing the phonological system to 'anticipate' (or partially activate) phonemes that were grouped together as an item subsequently in ISR.…”

“…Instead, it appears that there is a direct impact of lexical knowledge on phonological stability. ISR data such as these provide a strong case for verbal short-term memory drawing on long-term linguistic representations (Patterson, Graham, & Hodges, 1994;Jefferies et al, 2006a;Acheson, Hamidi, Binder, & Postle, 2011), in line with a wealth of studies which show effects of lexicality (i.e., words vs. nonwords: Hulme, Maughan, & Brown, Gordon, 1991;Hulme, Roodenrys, & Brown, 1995;Saint-Aubin & Poirier, 1999Majerus & Linden, 2003) and phonotactic M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 6 frequency (i.e., differences in phonotactic frequence between nonwords: Nimmo & Roodenrys, 2002;Majerus & Linden, 2003;Thorn & Frankish, 2005) on ISR accuracy at the whole-item level. We hypothesise that lexical learning involves acquiring a phoneme sequence, allowing the identity of upcoming phonological elements to be predicted, and that in ISR tasks, when several distinct items must be maintained simultaneously, these long-term phonological sequences are activated and place constraints on the order of phonological elements reducing phoneme migration errors.…”

“…Instead, the increased excitability elicited by anodal tDCS (during stimulation; Stagg & Nitsche, 2011) facilitated the acquisition of the phonological forms of the nonwords in long-term memory. This effect is likely to reflect the contributions of a number of neighbouring brain regions supporting aspects of phonological processing, including phonological short-term memory (Warrington & Shallice, 1969;Paulesu, Frith, & Frackowiak, 1993;Jonides et al, 1998;Henson, Burgess, & Frith, 2000;Buchsbaum & Esposito, 2008;Buchsbaum, Padmanabhan, & Berman, 2010;Acheson et al, 2011;Koenigs et al, 2011), phoneme sequencing (Gelfand & Bookheimer, 2003;Moser et al, 2009), translation of auditory to articulatory representations (Hickok & Poeppel, 2000;Papoutsi et al, 2009;Hickok, Houde, & Rong, 2011;Peschke, Ziegler, Eisenberger, & Baumgaertner, 2012), stimulus-driven attention (Downar, Crawley, Mikulis, & Davis, 2001;Ravizza, Hazeltine, Ruiz, & Zhu, 2011;Cabeza, Ciaramelli, & Moscovitch, 2012) and auditory processing for speech (posterior superior temporal cortex).…”

Dissociable components of phonological and lexical–semantic short-term memory and their relation to impaired word production in aphasia

“…Language-based models of STM have posited strong relationships between phonological and lexical-semantic language representations and STM (e.g., Acheson et al, 2011;Acheson & MacDonald, 2009a;2009b;Hickock, 2012;Majerus, 2009;2013;N. Martin & Saffran, 1992;R.…”

Working memory mediates the effects of gestational age at birth on expressive language development in children.

“…These data suggest that, while a gross effect of temporary memory upon language has been widely demonstrated (Baddeley, 2003;Baddeley, Gathercole & Papagno, 1998;Gathercole, Hitch, Service, & Martin, 1997), specific pathways might as well exist (Acheson, Hamidi, Binder, & Postle, 2011;Buchsbaum & D'Esposito, 2008;Jackson, Leitao, & Claessen, 2016).…”