The Neural Bases of the Short-Term Storage of Verbal Information Are Anatomically Variable across Individuals

Feredoes, Eva; Tononi, Giulio; Postle, Bradley R.

doi:10.1523/jneurosci.1573-07.2007

Cited by 57 publications

(52 citation statements)

References 24 publications

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“…term storage; ref. 24) in posterior category-selective extrastriate regions [fusiform face area (FFA) and parahippocampal place area (PPA) for faces and houses, respectively] (25-27). Additionally, during the delay period, external distraction could arise as visual stimuli from the opposite category to the memory targets (i.e., for face memory trials, any distracters were house stimuli, whereas for house memory trials, any distracters were face stimuli).…”

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confidence: 99%

Causal evidence for frontal involvement in memory target maintenance by posterior brain areas during distracter interference of visual working memory

Feredoes

Heinen

Weiskopf

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

179

172

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Dorsolateral prefrontal cortex (DLPFC) is recruited during visual working memory (WM) when relevant information must be maintained in the presence of distracting information. The mechanism by which DLPFC might ensure successful maintenance of the contents of WM is, however, unclear; it might enhance neural maintenance of memory targets or suppress processing of distracters. To adjudicate between these possibilities, we applied time-locked transcranial magnetic stimulation (TMS) during functional MRI, an approach that permits causal assessment of a stimulated brain region's influence on connected brain regions, and evaluated how this influence may change under different task conditions. Participants performed a visual WM task requiring retention of visual stimuli (faces or houses) across a delay during which visual distracters could be present or absent. When distracters were present, they were always from the opposite stimulus category, so that targets and distracters were represented in distinct posterior cortical areas. We then measured whether DLPFC-TMS, administered in the delay at the time point when distracters could appear, would modulate posterior regions representing memory targets or distracters. We found that DLPFC-TMS influenced posterior areas only when distracters were present and, critically, that this influence consisted of increased activity in regions representing the current memory targets. DLPFC-TMS did not affect regions representing current distracters. These results provide a new line of causal evidence for a top-down DLPFC-based control mechanism that promotes successful maintenance of relevant information in WM in the presence of distraction.external interference | top-down control D orsolateral prefrontal cortex (DLPFC) has long been associated with visual working memory (WM) function, with current models suggesting that it is a source of top-down control over posterior regions maintaining information across the short term (1, 2). One such control process is that of resistance to external distraction, when the appearance of irrelevant information in the visual scene could potentially interfere with maintenance of visual memoranda (3). Moreover, recent studies suggest that filtering of irrelevant information is one important determinant of WM capacity (4, 5), as irrelevant information may occupy limited storage resources that could otherwise be devoted to maintaining relevant information (4). Human lesion (6) and functional magnetic resonance imaging (fMRI) studies (7-9) indicate a specific role for the DLPFC when external distraction must be overcome during the maintenance phase of WM. However, little causal, temporally specific evidence exists on whether DLPFC acts during delays to suppress further processing of distracters (6,8,9) or whether it instead enhances neural representations of the maintained targets to protect them (7,10,11). One striking aspect of DLPFC responses is that they typically concern relevant stimuli (targets) but not irrelevant information (distracters) (11), inc...

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confidence: 99%

Causal evidence for frontal involvement in memory target maintenance by posterior brain areas during distracter interference of visual working memory

Feredoes

Heinen

Weiskopf

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

179

172

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“…Evidence in the auditory modality mainly stems from electrophysiology (3), suggesting that the function of auditory cortex goes beyond coding for simple features of complex sounds (4). In humans, the role of early sensory regions in short-term memory has not been directly addressed, because investigating auditory cortex is limited by the spatial and temporal resolution of functional MRI (fMRI) and the large interindividual differences in auditory cortex anatomy (5). Thus, existing fMRI studies of auditory short-term memory (ASTM) do not typically show significant or meaningful involvement of early auditory regions during the short-term maintenance of nonverbal sounds (6).…”

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confidence: 99%

Stimulus-specific suppression preserves information in auditory short-term memory

Linke

Vicente-Grabovetsky

Cusack

2011

Proc. Natl. Acad. Sci. U.S.A.

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Philosophers and scientists have puzzled for millennia over how perceptual information is stored in short-term memory. Some have suggested that early sensory representations are involved, but their precise role has remained unclear. The current study asks whether auditory cortex shows sustained frequency-specific activation while sounds are maintained in short-term memory using high-resolution functional MRI (fMRI). Investigating short-term memory representations within regions of human auditory cortex with fMRI has been difficult because of their small size and high anatomical variability between subjects. However, we overcame these constraints by using multivoxel pattern analysis. It clearly revealed frequency-specific activity during the encoding phase of a change detection task, and the degree of this frequency-specific activation was positively related to performance in the task. Although the sounds had to be maintained in memory, activity in auditory cortex was significantly suppressed. Strikingly, patterns of activity in this maintenance period correlated negatively with the patterns evoked by the same frequencies during encoding. Furthermore, individuals who used a rehearsal strategy to remember the sounds showed reduced frequency-specific suppression during the maintenance period. Although negative activations are often disregarded in fMRI research, our findings imply that decreases in blood oxygenation level-dependent response carry important stimulus-specific information and can be related to cognitive processes. We hypothesize that, during auditory change detection, frequency-specific suppression protects short-term memory representations from being overwritten by inhibiting the encoding of interfering sounds.individual differences | memory capacity | multivoxel pattern analysis S ounds are ephemeral, and to interpret, integrate, or compare them, it will often be necessary to generate a stable representation in some form of short-term memory. Auditory perception and short-term memory are, thus, closely linked processes, and recent findings suggest that early sensory regions are recruited by both (reviews in refs. 1 and 2). Evidence in the auditory modality mainly stems from electrophysiology (3), suggesting that the function of auditory cortex goes beyond coding for simple features of complex sounds (4). In humans, the role of early sensory regions in short-term memory has not been directly addressed, because investigating auditory cortex is limited by the spatial and temporal resolution of functional MRI (fMRI) and the large interindividual differences in auditory cortex anatomy (5). Thus, existing fMRI studies of auditory short-term memory (ASTM) do not typically show significant or meaningful involvement of early auditory regions during the short-term maintenance of nonverbal sounds (6).We focused on identifying whether human auditory cortex would show continuous stimulus-specific responses while participants had to remember sequences of simple tones. We drew on the well-established characteristic...

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“…Other work has very directly assessed the degree to which the location of representational and processing structure varies across individuals. In one particularly compelling study, Feredoes, Tononi, and Postle (2007) considered a discrepancy in the neuroimaging literature related to working memory: group-level analyses tend to yield data consistent with the hypothesis that the prefrontal cortex (PFC) serves as a working memory buffer, evidenced by a delay-period sensitivity to memory load, whereas single-subject case study analyses tended to not show this effect. Instead, single-subject analyses implicated quite different regions in different people.…”

Section: Heterogeneity Versus Homogeneity Of Locationmentioning

confidence: 99%

Connecting functional brain imaging and Parallel Distributed Processing

Cox

Seidenberg

Rogers

2014

Language, Cognition and Neuroscience

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The Neural Bases of the Short-Term Storage of Verbal Information Are Anatomically Variable across Individuals

Cited by 57 publications

References 24 publications

Causal evidence for frontal involvement in memory target maintenance by posterior brain areas during distracter interference of visual working memory

Causal evidence for frontal involvement in memory target maintenance by posterior brain areas during distracter interference of visual working memory

Stimulus-specific suppression preserves information in auditory short-term memory

Connecting functional brain imaging and Parallel Distributed Processing

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