scholarly journals Exogenous capture accounts for fundamental differences between prosaccade and antisaccade performance

2022 ◽  
Author(s):  
Allison T Goldstein ◽  
Terrence R Stanford ◽  
Emilio Salinas
Keyword(s):  
Target Selection ◽  
Correct Choice ◽  
Quantitative Model ◽  
Antisaccade Task ◽  
Visual Cue ◽  
Temporal Precision ◽  
Task Instructions ◽  
High Urgency ◽  
Model Predictions ◽  
Human Participants

Oculomotor circuits generate eye movements based on the physical salience of objects and current behavioral goals, exogenous and endogenous influences, respectively. However, the interactions between exogenous and endogenous mechanisms and their dynamic contributions to target selection have been difficult to resolve because they evolve extremely rapidly. In a recent study (Salinas et al., 2019), we achieved the necessary temporal precision using an urgent variant of the antisaccade task wherein motor plans are initiated early and choice accuracy depends sharply on when exactly the visual cue information becomes available. Empirical and modeling results indicated that the exogenous signal arrives ~80 ms after cue onset and rapidly accelerates the (incorrect) plan toward the cue, whereas the informed endogenous signal arrives ~25 ms later to favor the (correct) plan away from the cue. Here, we scrutinize a key mechanistic hypothesis about this dynamic, that the exogenous and endogenous signals act at different times and independently of each other. We test quantitative model predictions by comparing the performance of human participants instructed to look toward a visual cue versus away from it under high urgency. We find that, indeed, the exogenous response is largely impervious to task instructions; it simply flips its sign relative to the correct choice, and this largely explains the drastic differences in psychometric performance between the two tasks. Thus, saccadic choices are strongly dictated by the alignment between salience and behavioral goals.

scholarly journals Human low-threshold mechanoafferent responses to pure changes in friction controlled using an ultrasonic haptic device

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mariama Dione ◽  
Roger Holmes Watkins ◽  
Eric Vezzoli ◽  
Betty Lemaire-Semail ◽  
Johan Wessberg
Keyword(s):  
Central Nervous System ◽  
Stable Phase ◽  
Sensory Cues ◽  
Temporal Precision ◽  
Object Interaction ◽  
Tactile Stimulator ◽  
The Status ◽  
The Central Nervous System ◽  
Low Threshold ◽  
Human Participants

AbstractThe forces that are developed when manipulating objects generate sensory cues that inform the central nervous system about the qualities of the object’s surface and the status of the hand/object interaction. Afferent responses to frictional transients or slips have been studied in the context of lifting/holding tasks. Here, we used microneurography and an innovative tactile stimulator, the Stimtac, to modulate both the friction level of a surface, without changing the surface or adding a lubricant, and, to generate the frictional transients in a pure and net fashion. In three protocols, we manipulated: the frictional transients, the friction levels, the rise times, the alternation of phases of decrease or increase in friction to emulate grating-like stimuli. Afferent responses were recorded in 2 FAIs, 1 FAII, 2 SAIs and 3 SAIIs from the median nerve of human participants. Independently of the unit type, we observed that: single spikes were generated time-locked to the frictional transients, and that reducing the friction level reduced the number of spikes during the stable phase of the stimulation. Our results suggest that those frictional cues are encoded in all the unit types and emphasize the possibility to use the Stimtac device to control mechanoreceptor firing with high temporal precision.

Saccade Reaction Times Are Influenced by Caudate Microstimulation Following and Prior to Visual Stimulus Appearance

2011 ◽  
Vol 23 (7) ◽  
pp. 1794-1807 ◽  
Author(s):  
Masayuki Watanabe ◽  
Douglas P. Munoz
Keyword(s):  
Superior Colliculus ◽  
Visual Stimulus ◽  
Reaction Times ◽  
Electrical Microstimulation ◽  
Task Instructions ◽  
Linear Approach ◽  
Model Predictions ◽  
Saccade Control ◽  
Sensory Evidence ◽  
Task Conditions

Several cognitive models suggest that saccade RTs are controlled flexibly not only by mechanisms that accumulate sensory evidence after the appearance of a sensory stimulus (poststimulus mechanisms) but also by mechanisms that preset the saccade control system before the sensory event (prestimulus mechanisms). Consistent with model predictions, neurons in structures tightly related to saccade initiation, such as the superior colliculus and FEF, have poststimulus and prestimulus activities correlated with RTs. It has been hypothesized that the BG influence the saccade initiation process by controlling both poststimulus and prestimulus activities of superior colliculus and FEF neurons. To examine this hypothesis directly, we delivered electrical microstimulation to the caudate nucleus, the input stage of the oculomotor BG, while monkeys performed a prosaccade (look toward a visual stimulus) and antisaccade (look away from the stimulus) paradigm. Microstimulation applied after stimulus appearance (poststimulus microstimulation) prolonged RTs regardless of saccade directions (contra/ipsi) or task instructions (pro/anti). In contrast, microstimulation applied before stimulus appearance (prestimulus microstimulation) shortened RTs, although the effects were limited to several task conditions. The analysis of RT distributions using the linear approach to threshold with ergodic rate model revealed that poststimulus microstimulation prolonged RTs by reducing the rate of rise to the threshold for saccade initiation, whereas fitting results for prestimulus microstimulation were inconsistent across different task conditions. We conclude that both poststimulus and prestimulus activities of caudate neurons are sufficient to control saccade RTs.

A Perceptual Model of Pulse Salience and Metrical Accent in Musical Rhythms

1994 ◽  
Vol 11 (4) ◽  
pp. 409-464 ◽  
Author(s):  
Richard Parncutt
Keyword(s):  
Categorical Perception ◽  
Quantitative Model ◽  
Essential Factor ◽  
Pulse Period ◽  
Musical Rhythm ◽  
Temporal Precision ◽  
Recency Effects ◽  
Perceptual Model ◽  
Perceptual Salience ◽  
Musical Rhythms

In Experiment 1, six cyclically repeating interonset interval patterns (1,2:1,2:1:1,3:2:1,3:1:2, and 2:1:1:2) were each presented at six different note rates (very slow to very fast). Each trial began at a random point in the rhythmic cycle. Listeners were asked to tap along with the underlying beat or pulse. The number of times a given pulse (period, phase) was selected was taken as a measure of its perceptual salience. Responses gravitated toward a moderate pulse period of about 700 ms. At faster tempi, taps coincided more often with events followed by longer interonset intervals. In Experiment 2, listeners heard the same set of rhythmic patterns, plus a single sound in a different timbre, and were asked whether the extra sound fell on or off the beat. The position of the downbeat was found to be quite ambiguous. A quantitative model was developed from the following assumptions. The phenomenal accent of an event depends on the interonset interval that follows it, saturating for interonset intervals greater than about 1 s. The salience of a pulse sensation depends on the number of events matching a hypothetical isochronous template, and on the period of the template—pulse sensations are most salient in the vicinity of roughly 100 events per minute (moderate tempo). The metrical accent of an event depends on the saliences of pulse sensations including that event. Calculated pulse saliences and metrical accents according to the model agree well with experimental results (r > 0.85). The model may be extended to cover perceived meter, perceptible subdivisions of a beat, categorical perception, expressive timing, temporal precision and discrimination, and primacy/recency effects. The sensation of pulse may be the essential factor distinguishing musical rhythm from nonrhythm.

scholarly journals Interfering with a memory without erasing its trace

2019 ◽  
Author(s):  
Gesa Lange ◽  
Mario Senden ◽  
Alexandra Radermacher ◽  
Peter De Weerd
Keyword(s):  
Discrimination Task ◽  
Orientation Discrimination ◽  
Memory Mechanism ◽  
Open Questions ◽  
Model Predictions ◽  
Task Training ◽  
Human Participants ◽  
Similar Task ◽  
Training Protocol

AbstractPrevious research has shown that performance of a novice skill can be easily interfered with by subsequent training of another skill. We address the open questions whether extensively trained skills show the same vulnerability to interference as novice skills and which memory mechanism regulates interference between expert skills. We developed a recurrent neural network model of V1 able to learn from feedback experienced over the course of a long-term orientation discrimination experiment. After first exposing the model to one discrimination task for 3480 consecutive trials, we assessed how its performance was affected by subsequent training in a second, similar task. Training the second task strongly interfered with the first (highly trained) discrimination skill. The magnitude of interference depended on the relative amounts of training devoted to the different tasks. We used these and other model outcomes as predictions for a perceptual learning experiment in which human participants underwent the same training protocol as our model. Specifically, over the course of three months participants underwent baseline training in one orientation discrimination task for 15 sessions before being trained for 15 sessions on a similar task and finally undergoing another 15 sessions of training on the first task (to assess interference). Across all conditions, the pattern of interference observed empirically closely matched model predictions. According to our model, behavioral interference can be explained by antagonistic changes in neuronal tuning induced by the two tasks. Remarkably, this did not stem from erasing connections due to earlier learning but rather from a reweighting of lateral inhibition.

scholarly journals Task-related activity in human visual cortex

PLoS Biology ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. e3000921
Author(s):  
Zvi N. Roth ◽  
Minyoung Ryoo ◽  
Elisha P. Merriam
Keyword(s):  
Visual Cortex ◽  
Optical Imaging ◽  
Visual Stimulation ◽  
Field Of View ◽  
Imaging Studies ◽  
Related Activity ◽  
Temporal Precision ◽  
Human Participants ◽  
Visual Cortical ◽  
The Brain

The brain exhibits widespread endogenous responses in the absence of visual stimuli, even at the earliest stages of visual cortical processing. Such responses have been studied in monkeys using optical imaging with a limited field of view over visual cortex. Here, we used functional MRI (fMRI) in human participants to study the link between arousal and endogenous responses in visual cortex. The response that we observed was tightly entrained to task timing, was spatially extensive, and was independent of visual stimulation. We found that this response follows dynamics similar to that of pupil size and heart rate, suggesting that task-related activity is related to arousal. Finally, we found that higher reward increased response amplitude while decreasing its trial-to-trial variability (i.e., the noise). Computational simulations suggest that increased temporal precision underlies both of these observations. Our findings are consistent with optical imaging studies in monkeys and support the notion that arousal increases precision of neural activity.

scholarly journals A Polymer Model for Large-scale Chromatin Organization in Lower Eukaryotes

2002 ◽  
Vol 13 (6) ◽  
pp. 2157-2169 ◽  
Author(s):  
Joseph Ostashevsky
Keyword(s):  
Large Scale ◽  
Quantitative Model ◽  
Chromatin Organization ◽  
Contour Length ◽  
Model Predictions ◽  
Geometrical Constraints ◽  
Chromosome Associations ◽  
Diffusional Motion ◽  
G2 Phase ◽  
Nuclear Structures

A quantitative model of large-scale chromatin organization was applied to nuclei of fission yeast Schizosaccharomyces pombe (meiotic prophase and G2 phase), budding yeastSaccharomyces cerevisiae (young and senescent cells),Drosophila (embryonic cycles 10 and 14, and polytene tissues) and Caenorhabditis elegans (G1 phase). The model is based on the coil-like behavior of chromosomal fibers and the tight packing of discrete chromatin domains in a nucleus. Intrachromosomal domains are formed by chromatin anchoring to nuclear structures (e.g., the nuclear envelope). The observed sizes for confinement of chromatin diffusional motion are similar to the estimated sizes of corresponding domains. The model correctly predicts chromosome configurations (linear, Rabl, loop) and chromosome associations (homologous pairing, centromere and telomere clusters) on the basis of the geometrical constraints imposed by nuclear size and shape. Agreement between the model predictions and literature observations supports the notion that the average linear density of the 30-nm chromatin fiber is ∼4 nucleosomes per 10 nm contour length.

A Quantitative Model of Calcium and Phosphate Metabolism

1973 ◽  
Vol 95 (3) ◽  
pp. 279-284
Author(s):  
E. B. Reeve ◽  
K. A. Joiner
Keyword(s):  
Hormonal Regulation ◽  
Solubility Product ◽  
Renal Excretion ◽  
Calcium Absorption ◽  
Quantitative Model ◽  
Phosphate Metabolism ◽  
Model Predictions ◽  
Bone Calcification ◽  
Calcium And Phosphate Metabolism ◽  
Calcium Phosphate Precipitation

Equations are given which describe elementary features of the absorption, distribution, and excretion of calcium and phosphate in man. Vitamin and hormonal regulation is primarily of calcium absorption from the gut, calcium entry into and loss from bone and renal excretion of calcium and phosphate. Phosphate entry into and release from bone is determined by stoichiometric relations with calcium, while a high and a low extracellular Ca × P “solubility product” determine calcium phosphate precipitation in the extraosseous tissues and failure of bone calcification, respectively. The results of infusion experiments in man are compared with model predictions.

scholarly journals Attention expedites target selection by prioritizing the neural processing of distractor features

2020 ◽  
Author(s):  
Mandy V. Bartsch ◽  
Christian Merkel ◽  
Mircea A. Schoenfeld ◽  
Jens-Max Hopf
Keyword(s):  
Daily Life ◽  
Target Identification ◽  
Target Selection ◽  
Target Color ◽  
Neural Processing ◽  
Brain Response ◽  
Feature Representations ◽  
Feature Attention ◽  
Human Participants ◽  
Neural Gain

AbstractWhether doing the shopping, or driving the car – to navigate daily life, our brain has to rapidly identify relevant color signals among distracting ones. Despite a wealth of research, how color attention is dynamically adjusted is little understood. Previous studies suggest that the speed of feature attention depends on the time it takes to enhance the neural gain of cortical units tuned to the attended feature. To test this idea, we had human participants switch their attention on the fly between unpredicted target color alternatives, while recording the electroencephalographic brain response to probes matching the target, a non-target, or a distracting alternative target color. Paradoxically, we observed a temporally prioritized processing of distractor colors. A larger neural gain for the distractor followed by stronger attenuation expedited target identification. Our results suggest that dynamic adjustments of feature attention involve the temporally prioritized processing and elimination of distracting feature representations.

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