Auditory Short-term Memory Capacity Correlates with Gray Matter Density in the Left Posterior STS in Cognitively Normal and Dyslexic Adults

Abstract

Abstract■ A central feature of auditory STM is its item-limited processing capacity. We investigated whether auditory STM capacity correlated with regional gray and white matter in the structural MRI images from 74 healthy adults, 40 of whom had a prior diagnosis of developmental dyslexia whereas 34 had no history of any cognitive impairment. Using whole-brain statistics, we identified a region in the left posterior STS where gray matter density was positively correlated with forward digit span, backward digit span, and performance on a "spoonerisms" task that required both auditory STM and phoneme manipulation. Across tasks and participant groups, the correlation was highly significant even when variance related to reading and auditory nonword repetition was factored out. Although the dyslexics had poorer phonological skills, the effect of auditory STM capacity in the left STS was the same as in the cognitively normal group. We also illustrate that the anatomical location of this effect is in proximity to a lesion site recently associated with reduced auditory STM capacity in patients with stroke damage. This result, therefore, indicates that gray matter density in the posterior STS predicts auditory STM capacity in the healthy and damaged brain. In conclusion, we suggest that our present findings are consistent with the view that there is an overlap between the mechanisms that support language processing and auditory STM. ■

Areas of left perisylvian cortex mediate auditory–verbal short-term memory

“…Along these lines, recent studies demonstrate that posterior parietal cortex is critical for the manipulation or rearrangement of information in working memory, but not the basic short-term retention of information (Champod and Petrides, 2010; Koenigs et al, 2009). Integrating these results with the lesion data presented here and recent related findings (Acheson et al, 2011; Leff et al, 2009; Richardson et al, in press), we propose a neuroanatomical model of verbal STM with two key features: (1) the short-term maintenance of verbal information is mediated by a left hemisphere inferior-frontal/posterior-temporal circuit, and (2) the active manipulation or rearrangement of information within short-term memory additionally recruits posterior parietal cortices. Future research may serve to better characterize how these brain areas interact to facilitate the mental maintenance and manipulation of verbal information.…”

“…One of these studies showed that auditory STM capacity correlates with gray matter density in left posterior superior temporal cortex in normal and dyslexic adults (Richardson et al, in press). A second study showed that repetitive transcranial magnetic stimulation applied to a region of left posterior superior temporal gyrus important for the phonological encoding stage of speech production also impairs verbal STM performance (Acheson et al, 2011).…”

Phonological Working Memory for Words and Nonwords in Cerebral Cortex

“…Lesion studies, on the other hand, have overwhelmingly demonstrated that phonological working memory deficits are associated with specifically left hemisphere injury (e.g., Koenigs et al, 2011;Leff et al, 2009). Structural neuroimaging studies have also found relationships between superior temporal morphometry of the left, but not right, hemisphere and phonological working memory ability (Richardson et al, 2011). In the results of the present study, there were several plausible indications of a dominant left hemisphere role in phonological working memory: (a) Task-evoked response was greater in both left IFG and left SMA than their right homologues, (b) the effect of the parametric manipulation was stronger in left than right SMA, and (c) the correlation between activation in the nonword condition and behavioral performance on the CNRep was more reliable in the left STG than right.…”

“…A variety of methodological approaches now provide converging lines of evidence for the idea that superior temporal cortex is a critical component of the cortical network underlying phonological working memory on the basis of its operationalization in cognitive psychology. Superior temporal cortices are now routinely implicated in functional neuroimaging studies of auditory short-term memory (e.g., Buchsbaum et al, 2005;Strand, Forssberg, Klingberg, & Norrelgen, 2008), and anatomical neuroimaging studies have found correlations between the macroanatomical structure of the superior temporal cortex and verbal working memory capacity in individuals with both language-impaired and developmentally typical profiles (Lu et al, 2016;Richardson et al, 2011). These results parallel growing evidence from large-sample studies of auditory short-term memory deficits following brain injury, which specifically attribute this impairment to lesioned tissue in left superior temporal cortex (Koenigs et al, 2011;Leff et al, 2009).…”

Neurology of foreign language aptitude

“…The learning of new words and syntax are complex processes based on the functioning of WM, which underlies language learning in general (Robinson, 2003). Verbal WM, which is crucial for learning languages, is associated with grey matter density in the left posterior superior temporal sulcus (STS; Richardson et al, 2011).…”