Investigating the temporal dynamics and underlying mechanisms of cognitive fatigue.

2010 ◽  
pp. 127-147 ◽  
Author(s):  
Hans P. A. Van Dongen ◽  
Gregory Belenky ◽  
James M. Krueger
Keyword(s):  
Temporal Dynamics ◽  
Cognitive Fatigue ◽  
Underlying Mechanisms

scholarly journals An Inactivation Switch Enables Rhythms in a Neurospora Clock Model

2019 ◽  
Vol 20 (12) ◽  
pp. 2985 ◽  
Author(s):  
Abhishek Upadhyay ◽  
Michael Brunner ◽  
Hanspeter Herzel
Keyword(s):  
Feedback Loop ◽  
Design Principle ◽  
Temporal Dynamics ◽  
Model Organism ◽  
Transcription Activator ◽  
White Collar Complex ◽  
Living Organisms ◽  
Underlying Mechanisms ◽  
Molecular Components ◽  
Novel Model

Autonomous endogenous time-keeping is ubiquitous across many living organisms, known as the circadian clock when it has a period of about 24 h. Interestingly, the fundamental design principle with a network of interconnected negative and positive feedback loops is conserved through evolution, although the molecular components differ. Filamentous fungus Neurospora crassa is a well-established chrono-genetics model organism to investigate the underlying mechanisms. The core negative feedback loop of the clock of Neurospora is composed of the transcription activator White Collar Complex (WCC) (heterodimer of WC1 and WC2) and the inhibitory element called FFC complex, which is made of FRQ (Frequency protein), FRH (Frequency interacting RNA Helicase) and CK1a (Casein kinase 1a). While exploring their temporal dynamics, we investigate how limit cycle oscillations arise and how molecular switches support self-sustained rhythms. We develop a mathematical model of 10 variables with 26 parameters to understand the interactions and feedback among WC1 and FFC elements in nuclear and cytoplasmic compartments. We performed control and bifurcation analysis to show that our novel model produces robust oscillations with a wild-type period of 22.5 h. Our model reveals a switch between WC1-induced transcription and FFC-assisted inactivation of WC1. Using the new model, we also study the possible mechanisms of glucose compensation. A fairly simple model with just three nonlinearities helps to elucidate clock dynamics, revealing a mechanism of rhythms’ production. The model can further be utilized to study entrainment and temperature compensation.

scholarly journals Distinct spatiotemporal mechanisms underlie extra-classical receptive field modulation in macaque V1 microcircuits

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Christopher A Henry ◽  
Mehrdad Jazayeri ◽  
Robert M Shapley ◽  
Michael J Hawken
Keyword(s):  
Receptive Field ◽  
Temporal Dynamics ◽  
Scene Perception ◽  
Orientation Tuning ◽  
Context Modeling ◽  
Complex Scene ◽  
V1 Neurons ◽  
Classical Receptive Field ◽  
Spatio Temporal ◽  
Underlying Mechanisms

Complex scene perception depends upon the interaction between signals from the classical receptive field (CRF) and the extra-classical receptive field (eCRF) in primary visual cortex (V1) neurons. Although much is known about V1 eCRF properties, we do not yet know how the underlying mechanisms map onto the cortical microcircuit. We probed the spatio-temporal dynamics of eCRF modulation using a reverse correlation paradigm, and found three principal eCRF mechanisms: tuned-facilitation, untuned-suppression, and tuned-suppression. Each mechanism had a distinct timing and spatial profile. Laminar analysis showed that the timing, orientation-tuning, and strength of eCRF mechanisms had distinct signatures within magnocellular and parvocellular processing streams in the V1 microcircuit. The existence of multiple eCRF mechanisms provides new insights into how V1 responds to spatial context. Modeling revealed that the differences in timing and scale of these mechanisms predicted distinct patterns of net modulation, reconciling many previous disparate physiological and psychophysical findings.

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.

scholarly journals Underlying mechanisms of temporal dynamics in bistable perception

2019 ◽  
Vol 19 (10) ◽  
pp. 61c
Author(s):  
Yijun Ge ◽  
Ruanyuan Zhang ◽  
Chencan Qian ◽  
Chen Chen ◽  
Juraj Mesik ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Bistable Perception ◽  
Underlying Mechanisms

Challenges to understanding dynamics of biodiversity in time and space

Paleobiology ◽  
2003 ◽  
Vol 29 (1) ◽  
pp. 30-33 ◽  
Author(s):  
Michael R. Willig
Keyword(s):  
Temporal Dynamics ◽  
Anthropogenic Activities ◽  
Management Strategies ◽  
Global Scale ◽  
Population Increase ◽  
Negative Consequences ◽  
Environmental Biology ◽  
Regional Patterns ◽  
Causative Agents ◽  
Underlying Mechanisms

The negative consequences of anthropogenic activities such as agriculture and urbanization (e.g., deforestation, greenhouse gas emissions, and pollution) have become exacerbated by rapid rates of human population increase (see Pimm et al. 2001). Subsequent habitat loss and modification has accelerated rates of extinction, creating a biodiversity crises which arguably is one of the most pressing problems of the twenty-first century. Although causative agents are unclear, the fossil record suggests that biotas undergo periods of massive extinction as well as considerable diversification (Alroy et al. 2001; Jackson and Johnson 2001) at the global scale, even in the absence of human activities. As such, quantifying the spatial and temporal dynamics of biodiversity in past and contemporary times, and understanding their mechanistic bases represent disciplinary emphases of evolutionary and environmental biology. Equally important, such understanding is a critical step in informing regional as well as global management strategies and conservation efforts. Nonetheless, considerable controversy or uncertainty exists surrounding the patterns, underlying mechanisms, and strategies of conservation (Willig 2000; Andelman and Willig 2002). The past may provide important insights into a number of relevant issues regarding contemporary biodiversity (and vice versa), but only recently has the dialogue between neontologists and paleontologists charted productive areas of collaboration. Indeed, a growing body of work has questioned the meaning of global measures of biodiversity (past or present) and has suggested that only detailed studies at local sites provide resolution to important issues about biodiversity. This is due, in part, to considerable sampling problems associated with broad-scale estimation, including the averaging of local and regional patterns.

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 Rapid hydraulic collapse as cause of drought-induced mortality in conifers

2021 ◽  
Vol 118 (16) ◽  
pp. e2025251118
Author(s):  
Matthias Arend ◽  
Roman M. Link ◽  
Rachel Patthey ◽  
Günter Hoch ◽  
Bernhard Schuldt ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Water Relations ◽  
Hydraulic System ◽  
Temporal Dynamics ◽  
Severe Drought ◽  
Xylem Cavitation ◽  
Adult Trees ◽  
Hydraulic Safety ◽  
Underlying Mechanisms ◽  
Short Time

Understanding the vulnerability of trees to drought-induced mortality is key to predicting the fate of forests in a future climate with more frequent and intense droughts, although the underlying mechanisms are difficult to study in adult trees. Here, we explored the dynamic changes of water relations and limits of hydraulic function in dying adults of Norway spruce (Picea abies L.) during the progression of the record-breaking 2018 Central European drought. In trees on the trajectory to drought-induced mortality, we observed rapid, nonlinear declines of xylem pressure that commenced at the early onset of xylem cavitation and caused a complete loss of xylem hydraulic conductance within a very short time. We also observed severe depletions of nonstructural carbohydrates, though carbon starvation could be ruled out as the cause of the observed tree death, as both dying and surviving trees showed these metabolic limitations. Our observations provide striking field-based evidence for fast dehydration and hydraulic collapse as the cause of drought-induced mortality in adult Norway spruce. The nonlinear decline of tree water relations suggests that considering the temporal dynamics of dehydration is critical for predicting tree death. The collapse of the hydraulic system within a short time demonstrates that trees can rapidly be pushed out of the zone of hydraulic safety during the progression of a severe drought. In summary, our findings point toward a higher mortality risk for Norway spruce than previously assumed, which is in line with current reports of unprecedented levels of drought-induced mortality in this major European tree species.

scholarly journals The temporal dynamics of opportunity costs: A normative account of cognitive fatigue and boredom.

2021 ◽  
Author(s):  
Mayank Agrawal ◽  
Marcelo G. Mattar ◽  
Jonathan D. Cohen ◽  
Nathaniel D. Daw
Keyword(s):  
Temporal Dynamics ◽  
Opportunity Costs ◽  
Cognitive Fatigue ◽  
Normative Account

scholarly journals Distinct spatiotemporal mechanisms underlie extra-classical receptive field modulation in macaque V1 microcircuits

2019 ◽  
Author(s):  
Christopher A. Henry ◽  
Mehrdad Jazayeri ◽  
Robert M. Shapley ◽  
Michael J. Hawken
Keyword(s):  
Receptive Field ◽  
Temporal Dynamics ◽  
Scene Perception ◽  
Orientation Tuning ◽  
Context Modeling ◽  
Complex Scene ◽  
V1 Neurons ◽  
Classical Receptive Field ◽  
Spatio Temporal ◽  
Underlying Mechanisms

AbstractComplex scene perception depends upon the interaction between signals from the classical receptive field (CRF) and the extra-classical receptive field (eCRF) in primary visual cortex (V1) neurons. While much is known about V1 eCRF properties, it remains unknown how the underlying mechanisms map onto the cortical microcircuit. We probed the spatio-temporal dynamics of eCRF modulation using a reverse correlation paradigm, and found three principal eCRF mechanisms: tuned-facilitation, untuned-suppression, and tuned-suppression. Each mechanism had a distinct timing and spatial profile. Laminar analysis showed that the timing, orientation-tuning, and strength of eCRF mechanisms had distinct signatures within magnocellular and parvocellular processing streams in the V1 microcircuit. The existence of multiple eCRF mechanisms provides new insights into how V1 responds to spatial context. Modeling revealed that the differences in timing and scale of these mechanisms predicted distinct patterns of net modulation, reconciling many previous disparate physiological and psychophysical findings.

scholarly journals An inactivation switch enables rhythms in aNeurosporaclock model

2019 ◽  
Author(s):  
Abhishek Upadhyay ◽  
Michael Brunner ◽  
Hanspeter Herzel
Keyword(s):  
Feedback Loop ◽  
Design Principle ◽  
Temporal Dynamics ◽  
Model Organism ◽  
Transcription Activator ◽  
White Collar Complex ◽  
Living Organisms ◽  
Underlying Mechanisms ◽  
Molecular Components ◽  
Novel Model

AbstractAn autonomous endogenous time-keeping is ubiquitous across many living organisms known as circadian clock when it has a period of about 24 hours. Interestingly, the fundamental design principle with a network of interconnected negative and positive feedback loops is conserved through evolution, although the molecular components differ. Filamentous fungusNeurospora crassais a well established chrono-genetics model organism to investigate the underlying mechanisms. The core negative feedback loop of the clock ofNeurosporais composed of the transcription activator White Collar Complex (WCC) (heterodimer of WC1 and WC2) and the inhibitory element called FFC complex which is made of FRQ (Frequency protein), FRH (Frequency interacting RNA Helicase) and CK1a (Casein kinase 1a). While exploring their temporal dynamics we investigate how limit cycle oscillations arise and how molecular switches support self-sustained rhythms. We develop a mathematical model of 10 variables with 26 parameters to understand the interactions and feedbacks among WC1 and FFC elements in nuclear and cytoplasmic compartments. We performed control and bifurcation analysis to show that our novel model produces robust oscillations with a wild-type period of 22.5 hrs. Our model reveals a switch between WC1 induced transcription and FFC assisted inactivation of WC1. Using the new model we also study possible mechanisms of glucose compensation. A fairly simple model with just 3 non-linearities helps to elucidate clock dynamics revealing a mechanism of rhythms production. The model can further be utilized to study entrainment and temperature compensation.

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