Overlapping and distinct contributions of stimulus location and of spatial context to nonspatial visual short-term memory

Abstract

Stimulus location is not always informative during visual short-term memory (VSTM) for nonspatial features. Nevertheless, there is considerable evidence for the automatic encoding and retention of location information, regardless of its task relevance. To explore the functional and neural bases of the representation of spatial context in VSTM for nonspatial information, functional magnetic resonance imaging was performed while subjects performed delayed recall for the orientation of individual stimuli. Stimulus location varied across trials, and although this information was irrelevant for task performance, multivariate pattern analysis decoding of stimulus location sustained across trials, and also the decoding strength, predicted the precision of the recall of orientation. The influence of spatial context on the representation of orientation was operationalized by comparing the orientation reconstructions with multivariate inverted encoding models (IEM) trained in location context-dependent vs. -independent data. Although orientation reconstructions were robust for both location-dependent and location-independent IEMs, they were markedly stronger for the former. Furthermore, the functional relevance of location context was demonstrated by the fact that only the location-dependent neural representations of stimulus orientation predicted recall precision. NEW & NOTEWORTHY Neural representation strength of stimulus location predicts the precision of visual short-term memory (VSTM) recall of nonspatial stimulus, even when this information is task irrelevant. Neural representations of nonspatial stimuli that incorporate location context are stronger than those that do not, and only the former representations are strongly linked to behavior. The contributions to nonspatial VSTM performance of the representation of location context are at least partly distinct from those of the representation of stimulus content.

Different states of priority recruit different neural representations in visual working memory

“…For “PMI-trained IEMs,” the data on each trial were labeled according to the identity of the PMI at the time point of interest, and the converse was true for “UMI-trained” IEMs. Results from the PMI-trained IEMs would be the primary focus of this study because PMI-trained models have been shown to be valid and robust for various brain regions, including occipitotemporal cortex, IPS, and FEF [ 21 – 23 ].…”

“…When tested with UMI-labeled data, reconstructions from this PMI-trained IEM would index the extent to which the representational format of the UMI was similar to that of the PMI. Results from the PMI-trained IEMs would be the primary focus of this study because PMI-trained models have been shown to be valid and robust for various brain regions, including occipitotemporal cortex, IPS, and FEF [ 21 – 23 ]. For UMI-trained IEMs, the IEM was trained on data labeled according to the identity of the UMI and tested on data labeled according to the identity of the both the PMI and the UMI.…”

“…Note that although this aspect of the procedure meant that stimulus location was not task-critical (for example, one could ignore or forget where the samples had appeared and still succeed at the task), we expected that participants would nonetheless represent sample location in working memory. For example, previous work has indicated that stimulus location is encoded robustly during working memory for the orientation of individually presented stimuli [23,31].…”

The Neural Consequences of Attentional Prioritization of Internal Representations in Visual Working Memory

“…That is, if one or more neural codes are engaged uniquely by the MSR task, our approach would not be sensitive to this. Nonetheless, our experience from previous studies (e.g., Cai, Sheldon, Yu, & Postle, 2019;LaRocque et al, 2017) gave us confidence that this approach would be effective at testing our principal hypotheses of interest.…”

Delay-period activity in frontal, parietal, and occipital cortex tracks different attractor dynamics in visual working memory

“…The results reported here are from analyses carried out on existing data collected for other purposes [19,20]. Thirty individuals (10 males, mean age 20.7 ± 2. were displayed with equal spacing along the response wheel, and subjects registered their memory of the sample orientation by moving the cursor to the appropriate location on the response wheel and registering that location with a button press.…”