Neuron Activity Related to Short-Term Memory

Fuster, Joaquı́n M.; Alexander, Garrett E.

doi:10.1126/science.173.3997.652

Cited by 1,864 publications

(1,251 citation statements)

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“…This is exactly what has been reported now several times in unit recordings in the PFC of monkeys [5][6][7]28,33,39]. A few event-related fMRI studies have varied the length of the retention delay up to 24 s and have reported that the DLPFC activity does indeed span the entire delay [34 -37].…”

Section: Memory Load Effectssupporting

confidence: 76%

“…Neurophysiological studies of monkeys [5,6,8,25,28] and more recently event-related fMRI studies of humans [33 -37] have recorded persistent activity during retention intervals of delayed response tasks from the DLPFC (Fig. 2).…”

Section: Persistent Delay-period Activitymentioning

confidence: 99%

“…In the past 10 years, over a hundred functional magnetic resonance imaging (fMRI) studies of working memory in the human brain have been performed, many with the goal of understanding the function of the PFC. Many contemporary models of PFC function (Box 1) and working memory rely on attempts to integrate data from various methods such as single unit recordings in monkeys [5,6,8], neuropsychological performance of human neurological patients with focal lesions [9 -11], and more recently transcranical magnetic stimulation [12]. In this review, we critically evaluate how well new fMRI findings are compatible with current models of DLPFC function.…”

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confidence: 99%

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Persistent activity in the prefrontal cortex during working memory

Curtis

D’Esposito

2003

Trends in Cognitive Sciences

1,760

101

1,184

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The dorsolateral prefrontal cortex (DLPFC) plays a crucial role in working memory. Notably, persistent activity in the DLPFC is often observed during the retention interval of delayed response tasks. The code carried by the persistent activity remains unclear, however. We critically evaluate how well recent findings from functional magnetic resonance imaging studies are compatible with current models of the role of the DLFPC in working memory. These new findings suggest that the DLPFC aids in the maintenance of information by directing attention to internal representations of sensory stimuli and motor plans that are stored in more posterior regions.Working memory refers to the temporary representation of information that was just experienced or just retrieved from long-term memory. These active representations are short-lived, but can be maintained for longer periods of time through active rehearsal strategies, and can be subjected to various operations that manipulate the information in such a way that makes it useful for goaldirected behavior. Most definitions of working memory include both storage and (executive) control components [1]. Cognitive neuroscientists are searching for ways to disassociate the separate components of working memory in attempts to localize and clearly characterize their neural implementation. The prefrontal cortex (PFC) is thought to be the most important substrate for working memory (Fig. 1). Two key findings from studies of monkeys performing delayed response tasks suggest a crucial role for the PFC in working memory. First, experimental lesions of the principal sulcus in the dorsolateral prefrontal cortex (DLPFC) cause delay-dependent impairments [2][3][4]. That is, forgetting increases not only when a delay is imposed but increases with the length of the delay. Second, neurophysiological unit recordings from the DLPFC often show persistent, sustained levels of neuronal firing during the retention interval of delayed response Fig. 1. Lateral surface of (a) macaque and (b) human brain. The PFC is composed of lateral, medial, and orbital sectors that are believed to be functionally distinct given the selective effects of damage and distribution of afferent and efferent projections. The tinted areas correspond to those defined by Petrides and Pandya [71] based on cytoarchitecture and connectivity. Notably, the mid-DLPFC comprises areas 46 and 9/46 and the mid-VLPFC comprises areas 45 and 47/12. Note that much of area 46 lies in the depths of the principle sulcus of the monkey and the intermediate frontal sulcus of the human. Frontal premotor regions are also highlighted. The frontal eye field (F) in the macaque lies in the anterior bank of the arcuate sulcus in area 8A. In the human, F is found in the vicinity of the precentral sulcus and superior frontal sulcus junction (area 6 and maybe the caudal-most portion of 8A). The frontal eye field is a premotor region involved in the control of eye movements. Broca's area (B, area 44) is also a premotor area that is involved in the product...

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Section: Memory Load Effectssupporting

confidence: 76%

Section: Persistent Delay-period Activitymentioning

confidence: 99%

mentioning

confidence: 99%

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Persistent activity in the prefrontal cortex during working memory

Curtis

D’Esposito

2003

Trends in Cognitive Sciences

1,760

101

1,184

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“…Neurons in frontal and parietal cortex show slow dynamics, including persistent and ramping activity, related to motor planning [1][2][3][4] , action timing 5,6 , working memory [7][8][9][10] and decision making [11][12][13] . Neurons have intrinsic time constants on the order often milliseconds 14 .…”

Section: Introductionmentioning

confidence: 99%

Robust neuronal dynamics in premotor cortex during motor planning

Li¹,

Daie²,

Svoboda³

et al. 2016

Nature

461

485

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Neural activity maintains representations that bridge past and future events, often over many seconds. Network models can produce persistent and ramping activity, but the positive feedback that is critical for these slow dynamics can cause sensitivity to perturbations. Here we use electrophysiology and optogenetic perturbations in mouse premotor cortex to probe robustness of persistent neural representations during motor planning. Preparatory activity is remarkably robust to large-scale unilateral silencing: detailed neural dynamics that drive specific future movements were quickly and selectively restored by the network. Selectivity did not recover after bilateral silencing of premotor cortex. Perturbations to one hemisphere are thus corrected by information from the other hemisphere. Corpus callosum bisections demonstrated that premotor cortex hemispheres can maintain preparatory activity independently. Redundancy across selectively coupled modules, as we observed in premotor cortex, is a hallmark of robust control systems. Network models incorporating these principles show robustness that is consistent with data.

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“…At the neural level, it is often assumed that lateral prefrontal cortex (PFC) plays a critical role in the storage and maintenance of visual information. In line with this view, monkey single-neuron recording studies have demonstrated that PFC neurons are activated in a sustained fashion during the delay period of working memory tasks (e.g., Fuster & Alexander, 1971). While such observations suggest, that PFC might be the primary locus for the temporary storage of task-relevant information for future use (e.g., Goldman-Rakic, 1990), more recent studies have cast doubt on this hypothesis (see Postle, 2006;D'Esposito, 2007, for reviews).…”

Section: Introductionmentioning

confidence: 79%

Does visual working memory represent the predicted locations of future target objects? An event-related brain potential study

Grubert¹,

Eimer²

2015

Brain Research

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(2015) 'Does visual working memory represent the predicted locations of future target ob jects? An event-related brain potential study. ', Brain research., 1626 . pp. 258-266. Further information on publisher's website:https://doi.org/10.1016/j.brainres. 2014.10.011 Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Brain Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be re ected in this document. Changes may have been made to this work since it was submitted for publication. A de nitive version was subsequently published in Brain Research, 1626, 11 November 2015, 258-266, 10.1016/j.brainres.2014.011. Additional information:Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractDuring the maintenance of task-relevant objects in visual working memory, the contralateral delay activity (CDA) is elicited over the hemisphere opposite to the visual field where these objects are presented. The presence of this lateralised CDA component demonstrates the existence of position-dependent object representations in working memory. We employed a change detection task to investigate whether the represented object locations in visual working memory are shifted in preparation for the known location of upcoming comparison stimuli. On each trial, bilateral memory displays were followed after a delay period by bilateral test displays. Participants had to encode and maintain three visual objects on one side of the memory display, and to judge whether they were identical or different to three objects in the test display. Task-relevant memory and test stimuli were located in the same visual hemifield in the no-shift task, and on opposite sides in the horizontal shift task. CDA components of similar size were triggered contralateral to the memorized objects in both tasks. The absence of a polarity reversal of the CDA in the horizontal shift task demonstrated that there was no preparatory shift of memorized object location towards the side of the upcoming comparison stimuli. These results suggest that visual working memory represents the locations of visual objects during encoding, and that the matching of memorized and test objects at different locations is based on a comparison process that can bridge spatial translations between these objects.

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Neuron Activity Related to Short-Term Memory

Cited by 1,864 publications

References 13 publications

Persistent activity in the prefrontal cortex during working memory

Persistent activity in the prefrontal cortex during working memory

Robust neuronal dynamics in premotor cortex during motor planning

Does visual working memory represent the predicted locations of future target objects? An event-related brain potential study

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