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Brain activation during associative short-term memory maintenance is not predictive for subsequent retrieval.

Bergmann HC, Daselaar SM, Beul SF, Rijpkema M, Fernández G, Kessels RP - Front Hum Neurosci (2015)

Bottom Line: We examined which brain regions actually support successful WM processing, rather than being confounded by LTM processes, during the maintenance and probe phase of a WM task.No supra-threshold activation was found during the WM probe.Together, we obtained clearer insights in which brain regions support successful WM and LTM without the potential confound of the respective memory system.

View Article: PubMed Central - PubMed

Affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands.

ABSTRACT
Performance on working memory (WM) tasks may partially be supported by long-term memory (LTM) processing. Hence, brain activation recently being implicated in WM may actually have been driven by (incidental) LTM formation. We examined which brain regions actually support successful WM processing, rather than being confounded by LTM processes, during the maintenance and probe phase of a WM task. We administered a four-pair (faces and houses) associative delayed-match-to-sample (WM) task using event-related functional MRI (fMRI) and a subsequent associative recognition LTM task, using the same stimuli. This enabled us to analyze subsequent memory effects for both the WM and the LTM test by contrasting correctly recognized pairs with incorrect pairs for either task. Critically, with respect to the subsequent WM effect, we computed this analysis exclusively for trials that were forgotten in the subsequent LTM recognition task. Hence, brain activity associated with successful WM processing was less likely to be confounded by incidental LTM formation. The subsequent LTM effect, in contrast, was analyzed exclusively for pairs that previously had been correctly recognized in the WM task, disclosing brain regions involved in successful LTM formation after successful WM processing. Results for the subsequent WM effect showed no significantly activated brain areas for WM maintenance, possibly due to an insensitivity of fMRI to mechanisms underlying active WM maintenance. In contrast, a correct decision at WM probe was linked to activation in the "retrieval success network" (anterior and posterior midline brain structures). The subsequent LTM analyses revealed greater activation in left dorsolateral prefrontal cortex and posterior parietal cortex in the early phase of the maintenance stage. No supra-threshold activation was found during the WM probe. Together, we obtained clearer insights in which brain regions support successful WM and LTM without the potential confound of the respective memory system.

No MeSH data available.


Related in: MedlinePlus

Left panel: Brain areas related to successful LTM formation during the early WM maintenance phase (bottom left panel), equated for WM performance (WM+/LTM+ > WM+/LTM−). Successful LTM formation during the early WM delay phase was associated with greater activation in the left dorsolateral prefrontal cortex, left posterior parietal cortex/intraparietal sulcus and left temporal pole (the latter did not survive a multiple comparison correction). Right panel: Brain areas related to successful WM processing during the WM probe phase (top right), equated for LTM performance (WM+/LTM− > WM−/LTM−). A correct WM decision was associated with greater activation in the medial prefrontal cortex and precuneus (the latter did not survive a multiple comparison correction, though). Activation clusters (p < 0.001, uncorrected, >25 voxels) superimposed on averaged (n = 26) high-resolution T1-weighted images. Note: R = right.
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Figure 5: Left panel: Brain areas related to successful LTM formation during the early WM maintenance phase (bottom left panel), equated for WM performance (WM+/LTM+ > WM+/LTM−). Successful LTM formation during the early WM delay phase was associated with greater activation in the left dorsolateral prefrontal cortex, left posterior parietal cortex/intraparietal sulcus and left temporal pole (the latter did not survive a multiple comparison correction). Right panel: Brain areas related to successful WM processing during the WM probe phase (top right), equated for LTM performance (WM+/LTM− > WM−/LTM−). A correct WM decision was associated with greater activation in the medial prefrontal cortex and precuneus (the latter did not survive a multiple comparison correction, though). Activation clusters (p < 0.001, uncorrected, >25 voxels) superimposed on averaged (n = 26) high-resolution T1-weighted images. Note: R = right.

Mentions: Subsequent LTM effect equating for WM performance. For the LTM task, brain areas were identified that predicted strong LTM performance for pairs which had been correctly classified during the WM task (see Figure 5; Table 5). Here, we contrasted correctly recognized pairs in the WM task which were also correctly identified in the LTM task (with high confidence ratings) with pairs which were correctly identified during the WM task but not in the LTM task (i.e., WM+/LTM+ > WM+/LTM−). For the early maintenance phase, this analysis revealed greater activation in the left dorsolateral prefrontal cortex (local maximum at (−30, 45, 30); pFWE = 0.003) and left posterior parietal cortex/intraparietal sulcus (local maximum at (−54, −42, 55); pSVC = 0.022). As for the late stage of the WM maintenance phase, no brain regions exhibited differential activation for LTM hits vs. misses.


Brain activation during associative short-term memory maintenance is not predictive for subsequent retrieval.

Bergmann HC, Daselaar SM, Beul SF, Rijpkema M, Fernández G, Kessels RP - Front Hum Neurosci (2015)

Left panel: Brain areas related to successful LTM formation during the early WM maintenance phase (bottom left panel), equated for WM performance (WM+/LTM+ > WM+/LTM−). Successful LTM formation during the early WM delay phase was associated with greater activation in the left dorsolateral prefrontal cortex, left posterior parietal cortex/intraparietal sulcus and left temporal pole (the latter did not survive a multiple comparison correction). Right panel: Brain areas related to successful WM processing during the WM probe phase (top right), equated for LTM performance (WM+/LTM− > WM−/LTM−). A correct WM decision was associated with greater activation in the medial prefrontal cortex and precuneus (the latter did not survive a multiple comparison correction, though). Activation clusters (p < 0.001, uncorrected, >25 voxels) superimposed on averaged (n = 26) high-resolution T1-weighted images. Note: R = right.
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Related In: Results  -  Collection

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Figure 5: Left panel: Brain areas related to successful LTM formation during the early WM maintenance phase (bottom left panel), equated for WM performance (WM+/LTM+ > WM+/LTM−). Successful LTM formation during the early WM delay phase was associated with greater activation in the left dorsolateral prefrontal cortex, left posterior parietal cortex/intraparietal sulcus and left temporal pole (the latter did not survive a multiple comparison correction). Right panel: Brain areas related to successful WM processing during the WM probe phase (top right), equated for LTM performance (WM+/LTM− > WM−/LTM−). A correct WM decision was associated with greater activation in the medial prefrontal cortex and precuneus (the latter did not survive a multiple comparison correction, though). Activation clusters (p < 0.001, uncorrected, >25 voxels) superimposed on averaged (n = 26) high-resolution T1-weighted images. Note: R = right.
Mentions: Subsequent LTM effect equating for WM performance. For the LTM task, brain areas were identified that predicted strong LTM performance for pairs which had been correctly classified during the WM task (see Figure 5; Table 5). Here, we contrasted correctly recognized pairs in the WM task which were also correctly identified in the LTM task (with high confidence ratings) with pairs which were correctly identified during the WM task but not in the LTM task (i.e., WM+/LTM+ > WM+/LTM−). For the early maintenance phase, this analysis revealed greater activation in the left dorsolateral prefrontal cortex (local maximum at (−30, 45, 30); pFWE = 0.003) and left posterior parietal cortex/intraparietal sulcus (local maximum at (−54, −42, 55); pSVC = 0.022). As for the late stage of the WM maintenance phase, no brain regions exhibited differential activation for LTM hits vs. misses.

Bottom Line: We examined which brain regions actually support successful WM processing, rather than being confounded by LTM processes, during the maintenance and probe phase of a WM task.No supra-threshold activation was found during the WM probe.Together, we obtained clearer insights in which brain regions support successful WM and LTM without the potential confound of the respective memory system.

View Article: PubMed Central - PubMed

Affiliation: Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands.

ABSTRACT
Performance on working memory (WM) tasks may partially be supported by long-term memory (LTM) processing. Hence, brain activation recently being implicated in WM may actually have been driven by (incidental) LTM formation. We examined which brain regions actually support successful WM processing, rather than being confounded by LTM processes, during the maintenance and probe phase of a WM task. We administered a four-pair (faces and houses) associative delayed-match-to-sample (WM) task using event-related functional MRI (fMRI) and a subsequent associative recognition LTM task, using the same stimuli. This enabled us to analyze subsequent memory effects for both the WM and the LTM test by contrasting correctly recognized pairs with incorrect pairs for either task. Critically, with respect to the subsequent WM effect, we computed this analysis exclusively for trials that were forgotten in the subsequent LTM recognition task. Hence, brain activity associated with successful WM processing was less likely to be confounded by incidental LTM formation. The subsequent LTM effect, in contrast, was analyzed exclusively for pairs that previously had been correctly recognized in the WM task, disclosing brain regions involved in successful LTM formation after successful WM processing. Results for the subsequent WM effect showed no significantly activated brain areas for WM maintenance, possibly due to an insensitivity of fMRI to mechanisms underlying active WM maintenance. In contrast, a correct decision at WM probe was linked to activation in the "retrieval success network" (anterior and posterior midline brain structures). The subsequent LTM analyses revealed greater activation in left dorsolateral prefrontal cortex and posterior parietal cortex in the early phase of the maintenance stage. No supra-threshold activation was found during the WM probe. Together, we obtained clearer insights in which brain regions support successful WM and LTM without the potential confound of the respective memory system.

No MeSH data available.


Related in: MedlinePlus