scholarly journals Disrupted serial dependence suggests deficits in synaptic potentiation in anti-NMDAR encephalitis and schizophrenia

2019 ◽  
Author(s):  
H. Stein ◽  
J. Barbosa ◽  
M. Rosa-Justicia ◽  
L. Prades ◽  
A. Morató ◽  
...  
Keyword(s):  
Working Memory ◽  
Neural Activity ◽  
Synaptic Potentiation ◽  
Serial Dependence ◽  
Short Term ◽  
Memory Mechanism ◽  
Memory Accuracy ◽  
Nmdar Encephalitis ◽  
Term Potentiation ◽  
Cortical Excitation

AbstractWe report markedly reduced working memory-related serial dependence with preserved memory accuracy in anti-NMDAR encephalitis and schizophrenia. We argue that NMDAR-related changes in cortical excitation, while quickly destabilizing persistent neural activity, cannot fully account for a reduction of memory-dependent biases. Rather, our modeling results support a disruption of a memory mechanism operating on a longer timescale, such as short-term potentiation.

scholarly journals Reduced serial dependence suggests deficits in synaptic potentiation in anti-NMDAR encephalitis and schizophrenia

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Heike Stein ◽  
Joao Barbosa ◽  
Mireia Rosa-Justicia ◽  
Laia Prades ◽  
Alba Morató ◽  
...  
Keyword(s):  
Synaptic Potentiation ◽  
Serial Dependence ◽  
Nmdar Encephalitis

scholarly journals Temporal dynamics of implicit memory underlying serial dependence

2020 ◽  
Author(s):  
Cristiano Moraes Bilacchi ◽  
Esaú Ventura Pupo Sirius ◽  
André M. Cravo ◽  
Raymundo Machado de Azevedo Neto
Keyword(s):  
Short Term Memory ◽  
Temporal Dynamics ◽  
Response Variability ◽  
Serial Dependence ◽  
Short Term ◽  
Term Memory ◽  
Memory Mechanism ◽  
Current Information ◽  
Visuomotor Task ◽  
Over Time

AbstractSerial dependence is the effect in which the immediately preceding trial influences participants’ responses to the current stimulus. But for how long does this bias last in the absence of interference from other stimuli? Here, we had 20 healthy young adult participants (12 women) perform a coincident timing task using different inter-trial intervals to characterize the serial dependence effect as the time between trials increases. Our results show that serial dependence abruptly decreases after 1 s inter-trial interval, but it remains pronounced after that for up to 8 s. In addition, participants’ response variability slightly decreases over longer intervals. We discuss these results in light of recent models suggesting that serial dependence might rely on a short-term memory trace kept through changes in synaptic weights, which might explain its long duration and apparent stability over time.Statement of RelevanceRecent perceptual and motor experiences bias human behavior. For this serial bias to take place, the brain must keep information for at least the time between events to blend past and current information. Understanding the temporal dynamics of such memory traces might shed light into the short-term memory mechanism and integration of prior and current information. Here, we characterized the temporal dynamics of the serial biases that emerge in a visuomotor task by varying the length of the interval between successive events. Our results show response biases are still present even after intervals as long as 8 s and that participants’ response variability decreases over time. Serial dependence thus seems to rely on a memory mechanism that is both long lasting in the absence of interference and stable.

scholarly journals Theoretical distinction between functional states in working memory and their corresponding neural states

2020 ◽  
Author(s):  
Mark G. Stokes ◽  
Paul S. Muhle-Karbe ◽  
Nicholas E. Myers
Keyword(s):  
Working Memory ◽  
Neural Activity ◽  
Potential Role ◽  
Neural Mechanisms ◽  
Persistent Activity ◽  
Short Term ◽  
Functional Roles ◽  
Cognitive States ◽  
Neurophysiological Mechanisms ◽  
Functional States

Working memory (WM) is important for guiding behaviour, but not always immediately. Here we define a WM item that is currently relevant for guiding behaviour as the functionally ‘active’ item; whereas items maintained in WM, but not immediately relevant to behaviour, are functionally ‘latent’. Traditional neurophysiological theories of WM proposed that content is maintained via persistent neural activity (e.g., stable attractors); however, more recent theories have highlighted the potential role for ‘activity-silent’ mechanisms (e.g., short-term synaptic plasticity). Given these somewhat parallel dichotomies, it is tempting to associate functionally active and latent cognitive states of WM with persistent- activity and activity-silent neural mechanisms, respectively. In this article we caution against a one-to-one correspondence between functional and activity states. We argue that the principal theoretical requirement for active and latent WM is that the corresponding neural states play qualitatively different functional roles. We consider a number of candidate solutions, and conclude that the neurophysiological mechanisms for functionally active and latent WM items are theoretically independent of the distinction between persistent activity vs activity-silent WM.

scholarly journals Probing the limits of activity-silent non-conscious working memory

2018 ◽  
Author(s):  
Darinka Trübutschek ◽  
Sébastien Marti ◽  
Henrik Ueberschär ◽  
Stanislas Dehaene
Keyword(s):  
Working Memory ◽  
Information Processing ◽  
Neural Activity ◽  
Short Term Memory ◽  
Conscious Awareness ◽  
Cautionary Note ◽  
Short Term ◽  
Behavioral Studies ◽  
Stored Information ◽  
Beta Frequency

SummaryTwo types of working memory (WM) have recently been proposed: conscious active WM, depending on sustained neural activity, and activity-silent WM, requiring neither conscious awareness nor accompanying neural activity. However, whether both states support identical forms of information processing is unknown. Theory predicts that activity-silent states are confined to passive storage and cannot operate on stored information. To determine whether an explicit reactivation is required prior to the manipulation of information in WM, we evaluated whether participants could mentally rotate brief visual stimuli of variable subjective visibility. Behaviorally, even for unseen targets, subjects reported the rotated location above chance after several seconds. As predicted, however, such blindsight performance was accompanied by neural signatures of conscious reactivation at the time of mental rotation, including a sustained desynchronization in alpha/beta frequency and a decodable representation of participants’ guess and response. Our findings challenge the concept of genuine non-conscious “working” memory, argue that activity-silent states merely support passive short-term memory, and provide a cautionary note for purely behavioral studies of non-conscious information processing.

scholarly journals Implementation of Neuro-Memristive Synapse for Long-and Short-Term Bio-Synaptic Plasticity

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 644
Author(s):  
Zubaer I. Mannan ◽  
Hyongsuk Kim ◽  
Leon Chua
Keyword(s):  
Synaptic Plasticity ◽  
Diffusion Processes ◽  
Long Term Potentiation ◽  
Synaptic Potentiation ◽  
Short Term ◽  
Term Potentiation ◽  
Voltage Dependent ◽  
Strong Stimulation ◽  
Synaptic Responses

In this paper, we propose a complex neuro-memristive synapse that exhibits the physiological acts of synaptic potentiation and depression of the human-brain. Specifically, the proposed neuromorphic synapse efficiently imitates the synaptic plasticity, especially long-term potentiation (LTP) and depression (LTD), and short-term facilitation (STF) and depression (STD), phenomena of a biological synapse. Similar to biological synapse, the short- or long-term potentiation (STF and LTP) or depression (STD or LTD) of the memristive synapse are distinguished on the basis of time or repetition of input cycles. The proposed synapse is also designed to exhibit the effect of reuptake and neurotransmitters diffusion processes of a bio-synapse. In addition, it exhibits the distinct bio-realistic attributes, i.e., strong stimulation, exponentially decaying conductance trace of synapse, and voltage dependent synaptic responses, of a neuron. The neuro-memristive synapse is designed in SPICE and its bio-realistic functionalities are demonstrated via various simulations.

scholarly journals Persistent neural activity in auditory cortex is related to auditory working memory in humans and nonhuman primates

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ying Huang ◽  
Artur Matysiak ◽  
Peter Heil ◽  
Reinhard König ◽  
Michael Brosch
Keyword(s):  
Working Memory ◽  
Auditory Cortex ◽  
Neural Activity ◽  
Cognitive Capacity ◽  
Field Potentials ◽  
Short Term ◽  
Neuronal Populations ◽  
Direct Support ◽  
The Brain ◽  
Term Storage

Working memory is the cognitive capacity of short-term storage of information for goal-directed behaviors. Where and how this capacity is implemented in the brain are unresolved questions. We show that auditory cortex stores information by persistent changes of neural activity. We separated activity related to working memory from activity related to other mental processes by having humans and monkeys perform different tasks with varying working memory demands on the same sound sequences. Working memory was reflected in the spiking activity of individual neurons in auditory cortex and in the activity of neuronal populations, that is, in local field potentials and magnetic fields. Our results provide direct support for the idea that temporary storage of information recruits the same brain areas that also process the information. Because similar activity was observed in the two species, the cellular bases of some auditory working memory processes in humans can be studied in monkeys.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

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