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Juha Silvanto - One of the best experts on this subject based on the ideXlab platform.

  • Working Memory Maintenance: Sustained Firing or Synaptic Mechanisms?
    Trends in cognitive sciences, 2017
    Co-Authors: Juha Silvanto
    Abstract:

    According to conventional views, holding information in working Memory (WM) involves elevated and persistent neuronal firing. This has been challenged by models in which WM Maintenance is implemented by activity-silent synaptic mechanisms. A new study suggests that both have a role, consistent with cognitive models positing several states of WM. However, do these states reflect the operation of attention or awareness?

  • How Visual Short-Term Memory Maintenance Modulates Subsequent Visual Aftereffects
    Psychological Science, 2013
    Co-Authors: Elyana Saad, Juha Silvanto
    Abstract:

    Prolonged viewing of a visual stimulus can result in sensory adaptation, giving rise to perceptual phenomena such as the tilt aftereffect (TAE). However, it is not known if short-term Memory Maintenance induces such effects. We examined how visual short-term Memory (VSTM) Maintenance modulates the strength of the TAE induced by subsequent visual adaptation. We reasoned that if VSTM Maintenance induces aftereffects on subsequent encoding of visual information, then it should either enhance or reduce the TAE induced by a subsequent visual adapter, depending on the congruency of the Memory cue and the adapter. Our results were consistent with this hypothesis and thus indicate that the effects of VSTM Maintenance can outlast the Maintenance period.

Guillén Fernández - One of the best experts on this subject based on the ideXlab platform.

  • Early and late stages of working-Memory Maintenance contribute differentially to long-term Memory formation.
    Acta Psychologica, 2013
    Co-Authors: Heiko C. Bergmann, Anne Kiemeneij, Guillén Fernández, Roy P. C. Kessels
    Abstract:

    The present paper investigated the role of early and late stages of working-Memory Maintenance, which have been suggested to differentially contribute to long-term Memory formation. In experiment 1, we administered a delayed-match-to-sample task, requiring participants to remember line drawings of non-sense three-dimensional stimuli. In the delay phase, participants were either presented with a fixation cross (for 2 or 9 s) or with one of two different interference tasks, varying in visual overlap with the target. The interference task was presented 1.5, 4.5 or 7.5 s after target offset. Early interfering and early probing disproportionately affected performance on an unexpected subsequent recognition-Memory task compared to later interference or probing. This was not modulated by the type of interference task. In Experiment 2, we examined whether the formation of a holistic internal code of the target may be a gradual process. An analogous delayed-match-to-sample task was administered, with interference after 0.5, 2.5 or 4.5 s after target offset. The early and middle interference condition similarly disproportionately affected performance compared to later interference. Hence, the present results support the view of a functional dissociation between early and late stages of working-Memory Maintenance and that early working-Memory processes contribute particularly to long-term Memory formation.

  • the right hippocampus participates in short term Memory Maintenance of object location associations
    NeuroImage, 2006
    Co-Authors: Carinne Piekema, Rogier B Mars, Roy P. C. Kessels, Guillén Fernández, Karl Magnus Petersson
    Abstract:

    Doubts have been cast on the strict dissociation between short- and long-term Memory systems. Specifically, several neuroimaging studies have shown that the medial temporal lobe, a region almost invariably associated with long-term Memory, is involved in active short-term Memory Maintenance. Furthermore, a recent study in hippocampally lesioned patients has shown that the hippocampus is critically involved in associating objects and their locations, even when the delay period lasts only 8 s. However, the critical feature that causes the medial temporal lobe, and in particular the hippocampus, to participate in active Maintenance is still unknown. This study was designed in order to explore hippocampal involvement in active Maintenance of spatial and non-spatial associations. Eighteen participants performed a delayed-match-to-sample task in which they had to maintain either object–location associations, color–number association, single colors, or single locations. Whole-brain activity was measured using event-related functional magnetic resonance imaging and analyzed using a random effects model. Right lateralized hippocampal activity was evident when participants had to maintain object–location associations, but not when they had to maintain object–color associations or single items. The present results suggest a hippocampal involvement in active Maintenance when feature combinations that include spatial information have to be maintained online.

  • The right hippocampus participates in short-term Memory Maintenance of object–location associations
    NeuroImage, 2006
    Co-Authors: Carinne Piekema, Rogier B Mars, Roy P. C. Kessels, Karl Magnus Petersson, Guillén Fernández
    Abstract:

    Doubts have been cast on the strict dissociation between short- and long-term Memory systems. Specifically, several neuroimaging studies have shown that the medial temporal lobe, a region almost invariably associated with long-term Memory, is involved in active short-term Memory Maintenance. Furthermore, a recent study in hippocampally lesioned patients has shown that the hippocampus is critically involved in associating objects and their locations, even when the delay period lasts only 8 s. However, the critical feature that causes the medial temporal lobe, and in particular the hippocampus, to participate in active Maintenance is still unknown. This study was designed in order to explore hippocampal involvement in active Maintenance of spatial and non-spatial associations. Eighteen participants performed a delayed-match-to-sample task in which they had to maintain either object–location associations, color–number association, single colors, or single locations. Whole-brain activity was measured using event-related functional magnetic resonance imaging and analyzed using a random effects model. Right lateralized hippocampal activity was evident when participants had to maintain object–location associations, but not when they had to maintain object–color associations or single items. The present results suggest a hippocampal involvement in active Maintenance when feature combinations that include spatial information have to be maintained online.

Laure Buhry - One of the best experts on this subject based on the ideXlab platform.

  • The CAN-In network: A biologically inspired model for self-sustained theta oscillations and Memory Maintenance in the hippocampus.
    Hippocampus, 2017
    Co-Authors: Francesco Giovannini, Beate Knauer, Motoharu Yoshida, Laure Buhry
    Abstract:

    During working Memory tasks, the hippocampus exhibits synchronous theta-band activity, which is thought to be correlated with the short-term Memory Maintenance of salient stimuli. Recent studies indicate that the hippocampus contains the necessary circuitry allowing it to generate and sustain theta oscillations without the need of extrinsic drive. However, the cellular and network mechanisms supporting synchronous rhythmic activity are far from being fully understood. Based on electrophysiological recordings from hippocampal pyramidal CA1 cells, we present a possible mechanism for the Maintenance of such rhythmic theta-band activity in the isolated hippocampus. Our model network, based on the Hodgkin-Huxley formalism, comprising pyramidal neurons equipped with calcium-activated nonspecific cationic (CAN) ion channels, is able to generate and sustain synchronized theta oscillations (4-12 Hz), following a transient stimulation. The synchronous network activity is maintained by an intrinsic CAN current (ICAN ), in the absence of constant external input. When connecting the pyramidal-CAN network to fast-spiking inhibitory interneurons, the dynamics of the model reveal that feedback inhibition improves the robustness of fast theta oscillations, by tightening the synchronization of the pyramidal CAN neurons. The frequency and power of the theta oscillations are both modulated by the intensity of the ICAN , which allows for a wide range of oscillation rates within the theta band. This biologically plausible mechanism for the Maintenance of synchronous theta oscillations in the hippocampus aims at extending the traditional models of septum-driven hippocampal rhythmic activity. © 2017 Wiley Periodicals, Inc.

  • The CAN-In network: a biologically-inspired model for self-sustained theta oscillations and Memory Maintenance in the hippocampus
    Hippocampus, 2017
    Co-Authors: Francesco Giovannini, Beate Knauer, Motoharu Yoshida, Laure Buhry
    Abstract:

    During working Memory tasks, the hippocampus exhibits synchronous theta-band activity, which is thought to be correlated with the short-term Memory Maintenance of salient stimuli. Recent studies indicate that the hippocampus contains the necessary circuitry allowing it to generate and sustain theta oscillations without the need of extrinsic drive. However, the cellular and network mechanisms supporting synchronous rhythmic activity are far from being fully understood. Based on electro- physiological recordings from hippocampal pyramidal CA1 cells, we present a possible mechanism for the Maintenance of such rhythmic theta-band activity in the isolated hippocampus. Our model net- work, based on the Hodgkin-Huxley formalism, comprising pyramidal neurons equipped with calcium- activated non-specific cationic (CAN) ion channels, is able to generate and maintain synchronized theta oscillations (4 - 12Hz), following a transient stimulation. The synchronous network activity is maintained by an intrinsic CAN current (ICAN), in the absence of constant external input. The analysis of the dynamics of model networks of pyramidal-CAN and interneurons (CAN-In) reveals that feedback inhibition improves the robustness of fast theta oscillations, by tightening the synchro- nisation of the pyramidal CAN neurons. The frequency and power of the theta oscillations are both modulated by the intensity of the ICAN, which allows for a wide range of oscillation rates within the theta band. This biologically plausible mechanism for the Maintenance of synchronous theta oscil- lations in the hippocampus aims at extending the traditional models of septum-driven hippocampal rhythmic activity.

Christoph Kellendonk - One of the best experts on this subject based on the ideXlab platform.

  • Thalamic projections sustain prefrontal activity during working Memory Maintenance
    Nature Neuroscience, 2017
    Co-Authors: Scott S. Bolkan, Joseph M Stujenske, Sébastien Parnaudeau, Timothy Spellman, Caroline Rauffenbart, Atheir I. Abbas, Alexander Z. Harris, Joshua A. Gordon, Christoph Kellendonk
    Abstract:

    The mediodorsal thalamus (MD) shares reciprocal connectivity with the prefrontal cortex (PFC), and decreased MD–PFC connectivity is observed in schizophrenia patients. Patients also display cognitive deficits including impairments in working Memory, but a mechanistic link between thalamo–prefrontal circuit function and working Memory is missing. Using pathway-specific inhibition, we found directional interactions between mouse MD and medial PFC (mPFC), with MD-to-mPFC supporting working Memory Maintenance and mPFC-to-MD supporting subsequent choice. We further identify mPFC neurons that display elevated spiking during the delay, a feature that was absent on error trials and required MD inputs for sustained Maintenance. Strikingly, delay-tuned neurons had minimal overlap with spatially tuned neurons, and each mPFC population exhibited mutually exclusive dependence on MD and hippocampal inputs. These findings indicate a role for MD in sustaining prefrontal activity during working Memory Maintenance. Consistent with this idea, we found that enhancing MD excitability was sufficient to enhance task performance. Using pathway-specific optogenetic inhibition, the authors demonstrate that projections from the mediodorsal thalamus to prefrontal cortex support the Maintenance of working Memory, while prefrontal–thalamic projections support subsequent choice selection. Thalamo–prefrontal projections have a circuit-specific role in sustaining prefrontal delay-period activity, a neuronal signature required for successful task performance.

  • Thalamic projections sustain prefrontal activity during working Memory Maintenance.
    Nature neuroscience, 2017
    Co-Authors: Scott S. Bolkan, Joseph M Stujenske, Sébastien Parnaudeau, Timothy Spellman, Caroline Rauffenbart, Atheir I. Abbas, Alexander Z. Harris, Joshua A. Gordon, Christoph Kellendonk
    Abstract:

    The mediodorsal thalamus (MD) shares reciprocal connectivity with the prefrontal cortex (PFC), and decreased MD-PFC connectivity is observed in schizophrenia patients. Patients also display cognitive deficits including impairments in working Memory, but a mechanistic link between thalamo-prefrontal circuit function and working Memory is missing. Using pathway-specific inhibition, we found directional interactions between mouse MD and medial PFC (mPFC), with MD-to-mPFC supporting working Memory Maintenance and mPFC-to-MD supporting subsequent choice. We further identify mPFC neurons that display elevated spiking during the delay, a feature that was absent on error trials and required MD inputs for sustained Maintenance. Strikingly, delay-tuned neurons had minimal overlap with spatially tuned neurons, and each mPFC population exhibited mutually exclusive dependence on MD and hippocampal inputs. These findings indicate a role for MD in sustaining prefrontal activity during working Memory Maintenance. Consistent with this idea, we found that enhancing MD excitability was sufficient to enhance task performance.

Tal Makovski - One of the best experts on this subject based on the ideXlab platform.

  • the effect of working Memory Maintenance on long term Memory
    Memory & Cognition, 2019
    Co-Authors: Joshua K Hartshorne, Tal Makovski
    Abstract:

    Initially inspired by the Atkinson and Shiffrin model, researchers have spent a half century investigating whether actively maintaining an item in working Memory (WM) leads to improved subsequent long-term Memory (LTM). Empirical results have been inconsistent, and thus the answer to the question remains unclear. We present evidence from 13 new experiments as well as a meta-analysis of 61 published experiments. Both the new experiments and meta-analysis show clear evidence that increased WM Maintenance of a stimulus leads to superior recognition for that stimulus in subsequent LTM tests. This effect appears robust across a variety of experimental design parameters, suggesting that the variability in prior results in the literature is probably due to low power and random chance. The results support theories on which there is a close link between WM and LTM mechanisms, while challenging claims that this relationship is specific to verbal Memory and evolved to support language acquisition.