scholarly journals Strong inhibitory signaling underlies stable temporal dynamics and working memory in spiking neural networks

2020 ◽  
Author(s):  
Robert Kim ◽  
Terrence J. Sejnowski
Keyword(s):  
Working Memory ◽  
Task Performance ◽  
Cortical Neurons ◽  
Temporal Dynamics ◽  
Single Neurons ◽  
Multiple Timescales ◽  
Neural Data ◽  
Temporal Properties ◽  
Underlying Mechanisms ◽  
Inhibitory Signaling

AbstractCortical neurons process information on multiple timescales, and areas important for working memory (WM) contain neurons capable of integrating information over a long timescale. However, the underlying mechanisms for the emergence of neuronal timescales stable enough to support WM are unclear. By analyzing a spiking recurrent neural network (RNN) model trained on a WM task and activity of single neurons in the primate prefrontal cortex, we show that the temporal properties of our model and the neural data are remarkably similar. Dissecting our RNN model revealed strong inhibitory-to-inhibitory connections underlying a disinhibitory microcircuit as a critical component for long neuronal timescales and WM maintenance. We also found that enhancing inhibitory-to-inhibitory connections led to more stable temporal dynamics and improved task performance. Finally, we show that a network with such microcircuitry can perform other tasks without disrupting its pre-existing timescale architecture, suggesting that strong inhibitory signaling underlies a flexible WM network.

scholarly journals Spiking Recurrent Networks as a Model to Probe Neuronal Timescales Specific to Working Memory

2019 ◽  
Author(s):  
Robert Kim ◽  
Terrence J. Sejnowski
Keyword(s):  
Working Memory ◽  
Recurrent Neural Networks ◽  
Cortical Neurons ◽  
Receptive Fields ◽  
Hierarchical Organization ◽  
Recurrent Networks ◽  
Multiple Timescales ◽  
Underlying Mechanisms ◽  
Experimental Findings ◽  
Long Timescales

AbstractCortical neurons process and integrate information on multiple timescales. In addition, these timescales or temporal receptive fields display functional and hierarchical organization. For instance, areas important for working memory (WM), such as prefrontal cortex, utilize neurons with stable temporal receptive fields and long timescales to support reliable representations of stimuli. Despite of the recent advances in experimental techniques, the underlying mechanisms for the emergence of neuronal timescales long enough to support WM are unclear and challenging to investigate experimentally. Here, we demonstrate that spiking recurrent neural networks (RNNs) designed to perform a WM task reproduce previously observed experimental findings and that these models could be utilized in the future to study how neuronal timescales specific to WM emerge.

Effect of Static and Dynamic Heat Pain Stimulus Profiles on the Temporal Dynamics and Interdependence of Pain Qualities, Intensity, and Affect

2008 ◽  
Vol 100 (4) ◽  
pp. 1706-1715 ◽  
Author(s):  
Javeria A. Hashmi ◽  
Karen D. Davis
Keyword(s):  
Time Course ◽  
Temporal Dynamics ◽  
Constant Intensity ◽  
Dynamic Stimuli ◽  
Temporal Properties ◽  
Dynamic Stimulus ◽  
On Line ◽  
Underlying Mechanisms ◽  
S Peak ◽  
Time To Onset

Acute and chronic pains are characterized by a particular constellation of pain qualities, such as burning, aching, stinging, or sharp feelings. However, the temporal pattern of specific pain qualities and their relationship with pain and affect is not well understood. In addition, little is known about how the temperature time course of the stimulus impacts the temporal dynamics of pain qualities and the relationship between pain qualities. Therefore we applied two types of stimuli to the feet of 16 healthy subjects, each calibrated to evoke a similar pain magnitude (50/100): static stimulus held at constant intensity and dynamic stimulus increased in intensity in small steps. Stimulus runs consisted of three 30-s stimuli (either static or dynamic) with an interstimulus interval of 60 s. Continuous on-line ratings of pain, burning, sharp, stinging, cutting, and annoyance were obtained in separate runs, and the evoked responses were characterized by within-stimulus adaptation (early: 0- to 15-s peak vs. late: 25- to 40-s peak) and by their temporal properties (time to onset, peak, and end). The temporal profile of the burning sensation was similar to the pain and annoyance evoked by the static and dynamic stimuli. However, the sharp, stinging and cutting sensations attenuated in response to the static stimuli ( P < 0.01) but intensified along with pain and affect in response to the dynamic stimuli ( P < 0.05), whereas there was no attenuation in the evoked profiles of pain ( P = 0.61), annoyance ( P = 0.27), or burning quality ( P = 0.27). These data demonstrate that specific pain qualities with known differences in underlying mechanisms have distinct temporal dynamics that depend on the stimulus intensity dynamics.

Response Interference as a Mechanism Underlying Implicit Measures

2008 ◽  
Vol 24 (4) ◽  
pp. 218-225 ◽  
Author(s):  
Bertram Gawronski ◽  
Roland Deutsch ◽  
Etienne P. LeBel ◽  
Kurt R. Peters
Keyword(s):  
Task Performance ◽  
Psychological Research ◽  
Implicit Measures ◽  
Mediation Model ◽  
Response Interference ◽  
Relevant Evidence ◽  
Moderated Mediation Model ◽  
Stimulus Features ◽  
Underlying Mechanisms

Over the last decade, implicit measures of mental associations (e.g., Implicit Association Test, sequential priming) have become increasingly popular in many areas of psychological research. Even though successful applications provide preliminary support for the validity of these measures, their underlying mechanisms are still controversial. The present article addresses the role of a particular mechanism that is hypothesized to mediate the influence of activated associations on task performance in many implicit measures: response interference (RI). Based on a review of relevant evidence, we argue that RI effects in implicit measures depend on participants’ attention to association-relevant stimulus features, which in turn can influence the reliability and the construct validity of these measures. Drawing on a moderated-mediation model (MMM) of task performance in RI paradigms, we provide several suggestions on how to address these problems in research using implicit measures.

scholarly journals Resting‐State EEG Microstates Parallel Age‐Related Differences in Allocentric Spatial Working Memory Performance

2021 ◽  
Author(s):  
Adeline Jabès ◽  
Giuliana Klencklen ◽  
Paolo Ruggeri ◽  
Christoph M. Michel ◽  
Pamela Banta Lavenex ◽  
...  
Keyword(s):  
Older Adults ◽  
Working Memory ◽  
Resting State ◽  
Cognitive Aging ◽  
Temporal Dynamics ◽  
Spatial Working Memory ◽  
Brain Activity ◽  
Memory Performance ◽  
Brain Regions ◽  
Age Related

AbstractAlterations of resting-state EEG microstates have been associated with various neurological disorders and behavioral states. Interestingly, age-related differences in EEG microstate organization have also been reported, and it has been suggested that resting-state EEG activity may predict cognitive capacities in healthy individuals across the lifespan. In this exploratory study, we performed a microstate analysis of resting-state brain activity and tested allocentric spatial working memory performance in healthy adult individuals: twenty 25–30-year-olds and twenty-five 64–75-year-olds. We found a lower spatial working memory performance in older adults, as well as age-related differences in the five EEG microstate maps A, B, C, C′ and D, but especially in microstate maps C and C′. These two maps have been linked to neuronal activity in the frontal and parietal brain regions which are associated with working memory and attention, cognitive functions that have been shown to be sensitive to aging. Older adults exhibited lower global explained variance and occurrence of maps C and C′. Moreover, although there was a higher probability to transition from any map towards maps C, C′ and D in young and older adults, this probability was lower in older adults. Finally, although age-related differences in resting-state EEG microstates paralleled differences in allocentric spatial working memory performance, we found no evidence that any individual or combination of resting-state EEG microstate parameter(s) could reliably predict individual spatial working memory performance. Whether the temporal dynamics of EEG microstates may be used to assess healthy cognitive aging from resting-state brain activity requires further investigation.

scholarly journals Working Memory Performance under a Negative Affect Is More Susceptible to Higher Cognitive Workloads with Different Neural Haemodynamic Correlates

2021 ◽  
Vol 11 (7) ◽  
pp. 935
Author(s):  
Ying Xing Feng ◽  
Masashi Kiguchi ◽  
Wei Chun Ung ◽  
Sarat Chandra Dass ◽  
Ahmad Fadzil Mohd Hani ◽  
...  
Keyword(s):  
Working Memory ◽  
Task Performance ◽  
Memory Performance ◽  
Affective State ◽  
Memory Task ◽  
Interactive Effects ◽  
Functional Near Infrared Spectroscopy ◽  
Affective Factors ◽  
Related Stress ◽  
Haemodynamic Activity

The effect of stress on task performance is complex, too much or too little stress negatively affects performance and there exists an optimal level of stress to drive optimal performance. Task difficulty and external affective factors are distinct stressors that impact cognitive performance. Neuroimaging studies showed that mood affects working memory performance and the correlates are changes in haemodynamic activity in the prefrontal cortex (PFC). We investigate the interactive effects of affective states and working memory load (WML) on working memory task performance and haemodynamic activity using functional near-infrared spectroscopy (fNIRS) neuroimaging on the PFC of healthy participants. We seek to understand if haemodynamic responses could tell apart workload-related stress from situational stress arising from external affective distraction. We found that the haemodynamic changes towards affective stressor- and workload-related stress were more dominant in the medial and lateral PFC, respectively. Our study reveals distinct affective state-dependent modulations of haemodynamic activity with increasing WML in n-back tasks, which correlate with decreasing performance. The influence of a negative effect on performance is greater at higher WML, and haemodynamic activity showed evident changes in temporal, and both spatial and strength of activation differently with WML.

scholarly journals Supersaturation of VEP in Migraine without Aura Patients Treated with Topiramate: An Anatomo-Functional Biomarker of the Disease

2021 ◽  
Vol 10 (4) ◽  
pp. 769
Author(s):  
Ciro De Luca ◽  
Sara Gori ◽  
Sonia Mazzucchi ◽  
Elisa Dini ◽  
Martina Cafalli ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Cortical Neurons ◽  
Migraine Without Aura ◽  
Inverse Correlation ◽  
Primary Headache ◽  
Contrast Gain ◽  
High Prevalence ◽  
Functional Pathway ◽  
Inhibitory Signaling ◽  
Potential Use

Migraine is a primary headache with high prevalence among the general population, characterized by functional hypersensitivity to both exogenous and endogenous stimuli particularly affecting the nociceptive system. The hyperresponsivity of cortical neurons could be due to a disequilibrium in the excitatory/inhibitory signaling. This study aimed to investigate the anatomo-functional pathway from the retina to the primary visual cortex using visual evoked potentials (VEP). Contrast gain protocol was used in 15 patients diagnosed with migraine without aura (at baseline and after 3 months of topiramate therapy) and 13 controls. A saturation (S) index was assessed to monitor the response of VEP’s amplitude to contrast gain. Non-linear nor monotone growth of VEP (S < 0.95) was defined as supersaturation. A greater percentage of migraine patients (53%) relative to controls (7%) showed this characteristic. A strong inverse correlation was found between the S index and the number of days separating the registration of VEP from the next migraine attack. Moreover, allodynia measured through the Allodynia Symptoms Check-list (ASC-12) correlates with the S index both at baseline and after 3 months of topiramate treatment. Other clinical characteristics were not related to supersaturation. Topiramate therapy, although effective, did not influence electrophysiological parameters suggesting a non-intracortical nor retinal origin of the supersaturation (with possible involvement of relay cells from the lateral geniculate nucleus). In conclusion, the elaboration of visual stimuli and visual cortex activity is different in migraine patients compared to controls. More data are necessary to confirm the potential use of the S index as a biomarker for the migraine cycle (association with the pain-phase) and cortical sensitization (allodynia).

Visuospatial Working Memory Deficits and Visual Pursuit Impairments are Not Directly Related in Schizophrenia

2009 ◽  
Vol 43 (8) ◽  
pp. 766-774 ◽  
Author(s):  
Luca Cocchi ◽  
Francesca Bosisio ◽  
Olivia Carter ◽  
Stephen J. Wood ◽  
André Berchtold ◽  
...  
Keyword(s):  
Working Memory ◽  
Task Performance ◽  
Memory Performance ◽  
Correct Choice ◽  
Head Movements ◽  
Visuospatial Working Memory ◽  
Visual Pursuit ◽  
Scanning Time ◽  
Time Scanning ◽  
Correct Path

Objective: Patients with schizophrenia show deficits in visuospatial working memory and visual pursuit processes. It is currently unclear, however, whether both impairments are related to a common neuropathological origin. The purpose of the present study was therefore to examine the possible relations between the encoding and the discrimination of dynamic visuospatial stimuli in schizophrenia. Method: Sixteen outpatients with schizophrenia and 16 control subjects were asked to encode complex disc displacements presented on a screen. After a delay, participants had to identify the previously presented disc trajectory from a choice of six static linear paths, among which were five incorrect paths. The precision of visual pursuit eye movements during the initial presentation of the dynamic stimulus was assessed. The fixations and scanning time in definite regions of the six paths presented during the discrimination phase were investigated. Results: In comparison with controls, patients showed poorer task performance, reduced pursuit accuracy during incorrect trials and less time scanning the correct stimulus or the incorrect paths approximating its global structure. Patients also spent less time scanning the leftmost portion of the correct path even when making a correct choice. The accuracy of visual pursuit and head movements, however, was not correlated with task performance. Conclusions: The present study provides direct support for the hypothesis that active integration of visuospatial information within working memory is deficient in schizophrenia. In contrast, a general impairment of oculomotor mechanisms involved in smooth pursuit did not appear to be directly related to lower visuospatial working memory performance in schizophrenia.

scholarly journals Temporal Dynamics of Attention during Encoding versus Maintenance of Working Memory: Complementary Views from Event-related Potentials and Alpha-band Oscillations

2015 ◽  
Vol 27 (3) ◽  
pp. 492-508 ◽  
Author(s):  
Nicholas E. Myers ◽  
Lena Walther ◽  
George Wallis ◽  
Mark G. Stokes ◽  
Anna C. Nobre
Keyword(s):  
Working Memory ◽  
Visual Information ◽  
Temporal Dynamics ◽  
Recall Performance ◽  
Event Related Potentials ◽  
Alpha Band ◽  
Related Potentials ◽  
Frontoparietal Control Network ◽  
Anticipatory Attention ◽  
Processing Differences

Working memory (WM) is strongly influenced by attention. In visual WM tasks, recall performance can be improved by an attention-guiding cue presented before encoding (precue) or during maintenance (retrocue). Although precues and retrocues recruit a similar frontoparietal control network, the two are likely to exhibit some processing differences, because precues invite anticipation of upcoming information whereas retrocues may guide prioritization, protection, and selection of information already in mind. Here we explored the behavioral and electrophysiological differences between precueing and retrocueing in a new visual WM task designed to permit a direct comparison between cueing conditions. We found marked differences in ERP profiles between the precue and retrocue conditions. In line with precues primarily generating an anticipatory shift of attention toward the location of an upcoming item, we found a robust lateralization in late cue-evoked potentials associated with target anticipation. Retrocues elicited a different pattern of ERPs that was compatible with an early selection mechanism, but not with stimulus anticipation. In contrast to the distinct ERP patterns, alpha-band (8–14 Hz) lateralization was indistinguishable between cue types (reflecting, in both conditions, the location of the cued item). We speculate that, whereas alpha-band lateralization after a precue is likely to enable anticipatory attention, lateralization after a retrocue may instead enable the controlled spatiotopic access to recently encoded visual information.

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