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Decoding the content of visual short-term memory under distraction in occipital and parietal areas.

Bettencourt KC, Xu Y - Nat. Neurosci. (2015)

Bottom Line: We found that neither distractor presence nor predictability during the memory delay affected behavioral performance.Furthermore, we found no effect of target-distractor similarity on VSTM behavioral performance, further challenging the role of sensory regions in VSTM storage.Overall, consistent with previous univariate findings, our results indicate that superior IPS, but not occipital cortex, has a central role in VSTM storage.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Harvard University, Cambridge, Massachusetts, USA.

ABSTRACT
Recent studies have provided conflicting accounts regarding where in the human brain visual short-term memory (VSTM) content is stored, with strong univariate fMRI responses being reported in superior intraparietal sulcus (IPS), but robust multivariate decoding being reported in occipital cortex. Given the continuous influx of information in everyday vision, VSTM storage under distraction is often required. We found that neither distractor presence nor predictability during the memory delay affected behavioral performance. Similarly, superior IPS exhibited consistent decoding of VSTM content across all distractor manipulations and had multivariate responses that closely tracked behavioral VSTM performance. However, occipital decoding of VSTM content was substantially modulated by distractor presence and predictability. Furthermore, we found no effect of target-distractor similarity on VSTM behavioral performance, further challenging the role of sensory regions in VSTM storage. Overall, consistent with previous univariate findings, our results indicate that superior IPS, but not occipital cortex, has a central role in VSTM storage.

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Related in: MedlinePlus

Main experimental task from Experiments 1 and 3. Participants were shown two orientated gratings, and then cued as to which to remember. The cue presented here is enlarged for clarity. After a long delay, a third grating appeared and they were asked to judge whether this grating was jittered clockwise or counterclockwise to the remembered grating. During the delay, participants either saw a blank screen with a fixation dot (trials without distractors) or a sequential presentation of task irrelevant faces or gazebos (trials with distractors). In Experiment 1, trials without distractors were presented in the first half of the experiment while those with distractors were presented in the second half, making distractor presence/absence predictable. In Experiment 3, the two types of trials were randomly intermixed within a run, making distractor presence/absence unpredictable.
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Figure 1: Main experimental task from Experiments 1 and 3. Participants were shown two orientated gratings, and then cued as to which to remember. The cue presented here is enlarged for clarity. After a long delay, a third grating appeared and they were asked to judge whether this grating was jittered clockwise or counterclockwise to the remembered grating. During the delay, participants either saw a blank screen with a fixation dot (trials without distractors) or a sequential presentation of task irrelevant faces or gazebos (trials with distractors). In Experiment 1, trials without distractors were presented in the first half of the experiment while those with distractors were presented in the second half, making distractor presence/absence predictable. In Experiment 3, the two types of trials were randomly intermixed within a run, making distractor presence/absence unpredictable.

Mentions: To assess the role of both occipital and parietal cortices in VSTM storage under visual distraction (Experiment 1), we adapted the oriented grating VSTM task used by Harrison and Tong 13, which was previously shown to elicit robust VSTM decoding within occipital cortex, and manipulated whether or not distractors were present during the delay period (See Fig. 1). Ten participants were shown two gratings (~25º or ~115º) sequentially at fixation and then retroactively cued as to which orientation to remember. After an extended delay (11s), a third grating appeared at fixation and participants reported whether this grating was jittered clockwise or counterclockwise from the remembered grating. During the delay, either a blank screen (trials without distractors) or a series of face or gazebo stimuli (trials with distractors) were presented. In an effort to replicate the findings in Harrison and Tong 13 and to minimize any changes in VSTM strategy brought on by the distractors, all participants completed all eight blocks of trials without distractors before switching to trials with distractors. Participants were thus able to anticipate, with 100% accuracy, whether a given block of trials would contain distractors.


Decoding the content of visual short-term memory under distraction in occipital and parietal areas.

Bettencourt KC, Xu Y - Nat. Neurosci. (2015)

Main experimental task from Experiments 1 and 3. Participants were shown two orientated gratings, and then cued as to which to remember. The cue presented here is enlarged for clarity. After a long delay, a third grating appeared and they were asked to judge whether this grating was jittered clockwise or counterclockwise to the remembered grating. During the delay, participants either saw a blank screen with a fixation dot (trials without distractors) or a sequential presentation of task irrelevant faces or gazebos (trials with distractors). In Experiment 1, trials without distractors were presented in the first half of the experiment while those with distractors were presented in the second half, making distractor presence/absence predictable. In Experiment 3, the two types of trials were randomly intermixed within a run, making distractor presence/absence unpredictable.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4696876&req=5

Figure 1: Main experimental task from Experiments 1 and 3. Participants were shown two orientated gratings, and then cued as to which to remember. The cue presented here is enlarged for clarity. After a long delay, a third grating appeared and they were asked to judge whether this grating was jittered clockwise or counterclockwise to the remembered grating. During the delay, participants either saw a blank screen with a fixation dot (trials without distractors) or a sequential presentation of task irrelevant faces or gazebos (trials with distractors). In Experiment 1, trials without distractors were presented in the first half of the experiment while those with distractors were presented in the second half, making distractor presence/absence predictable. In Experiment 3, the two types of trials were randomly intermixed within a run, making distractor presence/absence unpredictable.
Mentions: To assess the role of both occipital and parietal cortices in VSTM storage under visual distraction (Experiment 1), we adapted the oriented grating VSTM task used by Harrison and Tong 13, which was previously shown to elicit robust VSTM decoding within occipital cortex, and manipulated whether or not distractors were present during the delay period (See Fig. 1). Ten participants were shown two gratings (~25º or ~115º) sequentially at fixation and then retroactively cued as to which orientation to remember. After an extended delay (11s), a third grating appeared at fixation and participants reported whether this grating was jittered clockwise or counterclockwise from the remembered grating. During the delay, either a blank screen (trials without distractors) or a series of face or gazebo stimuli (trials with distractors) were presented. In an effort to replicate the findings in Harrison and Tong 13 and to minimize any changes in VSTM strategy brought on by the distractors, all participants completed all eight blocks of trials without distractors before switching to trials with distractors. Participants were thus able to anticipate, with 100% accuracy, whether a given block of trials would contain distractors.

Bottom Line: We found that neither distractor presence nor predictability during the memory delay affected behavioral performance.Furthermore, we found no effect of target-distractor similarity on VSTM behavioral performance, further challenging the role of sensory regions in VSTM storage.Overall, consistent with previous univariate findings, our results indicate that superior IPS, but not occipital cortex, has a central role in VSTM storage.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Harvard University, Cambridge, Massachusetts, USA.

ABSTRACT
Recent studies have provided conflicting accounts regarding where in the human brain visual short-term memory (VSTM) content is stored, with strong univariate fMRI responses being reported in superior intraparietal sulcus (IPS), but robust multivariate decoding being reported in occipital cortex. Given the continuous influx of information in everyday vision, VSTM storage under distraction is often required. We found that neither distractor presence nor predictability during the memory delay affected behavioral performance. Similarly, superior IPS exhibited consistent decoding of VSTM content across all distractor manipulations and had multivariate responses that closely tracked behavioral VSTM performance. However, occipital decoding of VSTM content was substantially modulated by distractor presence and predictability. Furthermore, we found no effect of target-distractor similarity on VSTM behavioral performance, further challenging the role of sensory regions in VSTM storage. Overall, consistent with previous univariate findings, our results indicate that superior IPS, but not occipital cortex, has a central role in VSTM storage.

Show MeSH
Related in: MedlinePlus