scholarly journals Decoding and perturbing decision states in real time

2019 ◽  
Author(s):  
Diogo Peixoto ◽  
Jessica R. Verhein ◽  
Roozbeh Kiani ◽  
Jonathan C. Kao ◽  
Paul Nuyujukian ◽  
...  
Keyword(s):  
Real Time ◽  
Decision Process ◽  
Choice Behavior ◽  
Decision Variable ◽  
Behavioral Studies ◽  
Statistical Regularities ◽  
Sensory Evidence ◽  
Multiple Samples ◽  
Trial Evidence ◽  
Large Moment

SummaryIn dynamic environments, subjects often integrate multiple samples of a signal and combine them to reach a categorical judgment. The process of deliberation on the evidence can be described by a time-varying decision variable (DV), decoded from neural activity, that predicts a subject’s decision at the end of a trial. However, within trials, large moment-to-moment fluctuations of the DV are observed. The behavioral significance of these fluctuations and their role in the decision process remain unclear. Here we show that within-trial DV fluctuations decoded in real time from motor cortex are tightly linked to choice behavior, and that robust changes in DV sign have the statistical regularities expected from behavioral studies of changes-of-mind. Furthermore, we find single-trial evidence for absorbing decision bounds. As the DV builds up, heavily favoring one or the other choice, moment-to-moment variability in the DV is reduced, and both neural DV and behavioral decisions become resistant to additional pulses of sensory evidence as predicted by diffusion-to-bound and attractor models of the decision process.

scholarly journals The Relative Influences of Priors and Sensory Evidence on an Oculomotor Decision Variable During Perceptual Learning

2008 ◽  
Vol 100 (5) ◽  
pp. 2653-2668 ◽  
Author(s):  
Joshua I. Gold ◽  
Chi-Tat Law ◽  
Patrick Connolly ◽  
Sharath Bennur
Keyword(s):  
Choice Behavior ◽  
Weighted Average ◽  
Decision Variable ◽  
Visually Guided ◽  
Motor Tasks ◽  
Temporal Area ◽  
Sequential Dependencies ◽  
Sensory Motor ◽  
Sensory Evidence ◽  
Dot Motion

Choice behavior on simple sensory-motor tasks can exhibit trial-to-trial dependencies. For perceptual tasks, these dependencies reflect the influence of prior trials on choices that are also guided by sensory evidence, which is often independent across trials. Here we show that the relative influences of prior trials and sensory evidence on choice behavior can be shaped by training, such that prior influences are strongest when perceptual sensitivity to the relevant sensory evidence is weakest and then decline steadily as sensitivity improves. We trained monkeys to decide the direction of random-dot motion and indicate their decision with an eye movement. We characterized sequential dependencies by relating current choices to weighted averages of prior choices. We then modeled behavior as a drift-diffusion process, in which the weighted average of prior choices provided an additive offset to a decision variable that integrated incoming motion evidence to govern choice. The average magnitude of offset within individual training sessions declined steadily as the quality of the integrated motion evidence increased over many months of training. The trial-by-trial magnitude of offset was correlated with signals related to developing commands that generate the oculomotor response but not with neural activity in either the middle temporal area, which represents information about the motion stimulus, or the lateral intraparietal area, which represents the sensory-motor conversion. The results suggest that training can shape the relative contributions of expectations based on prior trends and incoming sensory evidence to select and prepare visually guided actions.

scholarly journals Transient neuronal suppression for exploitation of new sensory evidence

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Maxwell Shinn ◽  
Daeyeol Lee ◽  
John D. Murray ◽  
Hyojung Seo
Keyword(s):  
Decision Making ◽  
Neural Activity ◽  
Temporal Integration ◽  
Motor Preparation ◽  
Stimulus Onset ◽  
Frontal Eye Field ◽  
Perceptual Decision Making ◽  
Behavioral Studies ◽  
The Face ◽  
Sensory Evidence

AbstractIn noisy but stationary environments, decisions should be based on the temporal integration of sequentially sampled evidence. This strategy has been supported by many behavioral studies and is qualitatively consistent with neural activity in multiple brain areas. By contrast, decision-making in the face of non-stationary sensory evidence remains poorly understood. Here, we trained monkeys to identify and respond via saccade to the dominant color of a dynamically refreshed bicolor patch that becomes informative after a variable delay. Animals’ behavioral responses were briefly suppressed after evidence changes, and many neurons in the frontal eye field displayed a corresponding dip in activity at this time, similar to that frequently observed after stimulus onset but sensitive to stimulus strength. Generalized drift-diffusion models revealed consistency of behavior and neural activity with brief suppression of motor output, but not with pausing or resetting of evidence accumulation. These results suggest that momentary arrest of motor preparation is important for dynamic perceptual decision making.

scholarly journals Changes of mind and absolute evidence

2019 ◽  
Author(s):  
William Turner ◽  
Daniel Feuerriegel ◽  
Milan Andrejevic ◽  
Robert Hester ◽  
Stefan Bode
Keyword(s):  
Decision Process ◽  
Initial Response ◽  
Luminance Ratio ◽  
Noise Sources ◽  
Initial Decision ◽  
Luminance Difference ◽  
The World ◽  
Sensory Evidence

To navigate the world safely, we often need to rapidly ‘change our mind’ about decisions. Current models assume that initial decisions and change-of-mind decisions draw upon common sources of sensory evidence. In two-choice scenarios, this evidence may be ‘relative’ or ‘absolute’. For example, when judging which of two objects is the brightest, the luminance difference and luminance ratio between the two objects are sources of ‘relative’ evidence, which are invariant across additive and multiplicative luminance changes. Conversely, the overall luminance of the two objects combined is a source of ‘absolute’ evidence, which necessarily varies across symmetric luminance manipulations. Previous studies have shown that initial decisions are sensitive to both relative and absolute evidence; however, it is unknown whether change-of-mind decisions are sensitive to absolute evidence. Here, we investigated this question across two experiments. In each experiment participants indicated which of two flickering greyscale squares was brightest. Following an initial decision, the stimuli remained on screen for a brief period and participants could change their response. To investigate the effect of absolute evidence, the overall luminance of the two squares was varied whilst either the luminance difference (Experiment 1) or luminance ratio (Experiment 2) was held constant. In both experiments we found that increases in absolute evidence led to faster, less accurate initial responses and slower changes of mind. Change-of-mind accuracy decreased when the luminance difference was held constant, but remained unchanged when the luminance ratio was fixed. The initial response effects could be explained by the presence of input-dependent noise within the decision process, varying either within or across trials. However, the change-of-mind effects could not be captured by existing models, nor by two modified models which included input-dependent noise sources. This suggests that that the continued integration of sensory evidence following an initial decision operates differently to that described in existing theoretical accounts.

Fast Identification of 1,3-Dimethylamylamine Using Direct Analysis in Real Time-QToF-MS

2015 ◽  
Vol 98 (3) ◽  
pp. 757-759 ◽  
Author(s):  
Bharathi Avula ◽  
Troy J Smillie ◽  
Yan-Hong Wang ◽  
Jerry Zweigenbaum ◽  
Mahmoud A ElSohly ◽  
...  
Keyword(s):  
Dietary Supplements ◽  
Real Time ◽  
Plant Material ◽  
Direct Analysis ◽  
Exact Mass ◽  
Central Nervous System Stimulant ◽  
Three Samples ◽  
Positive Mode ◽  
The Central Nervous System ◽  
Multiple Samples

Abstract The central nervous system stimulant 1,3-dimethylamylamine (DMAA) has been found in preworkout products and dietary supplements. A fast direct analysis in real time-quadrupole time of flight-MS method was used for identification of DMAA in dietary supplements and to determine if this compound is present in geranium (Pelargonium graveolens) plants or oil. This method involved the use of [M+H]+ ions in the positive mode based on the exact mass of DMAA. The results of this investigation showed that DMAA was not detected from authentic samples of P. graveolens plant material or pelargonium oil or in multiple samples of commercially available pelargonium oil. DMAA was detected in three samples of dietary supplements. The LOD of DMAA was found to be 10 ng/mL.

scholarly journals Preserved capacity for learning statistical regularities and directing selective attention after hippocampal lesions

2019 ◽  
Vol 116 (39) ◽  
pp. 19705-19710 ◽  
Author(s):  
Nuttida Rungratsameetaweemana ◽  
Larry R. Squire ◽  
John T. Serences
Keyword(s):  
Information Processing ◽  
Prior Knowledge ◽  
Human Perception ◽  
Motion Direction ◽  
Hippocampal Lesions ◽  
Perceptual Performance ◽  
Statistical Regularities ◽  
Probabilistic Structure ◽  
Sensory Evidence ◽  
Task Conditions

Prior knowledge about the probabilistic structure of visual environments is necessary to resolve ambiguous information about objects in the world. Expectations based on stimulus regularities exert a powerful influence on human perception and decision making by improving the efficiency of information processing. Another type of prior knowledge, termed top-down attention, can also improve perceptual performance by facilitating the selective processing of relevant over irrelevant information. While much is known about attention, the mechanisms that support expectations about statistical regularities are not well-understood. The hippocampus has been implicated as a key structure involved in or perhaps necessary for the learning of statistical regularities, consistent with its role in various kinds of learning and memory. Here, we tested this hypothesis using a motion discrimination task in which we manipulated the most likely direction of motion, the degree of attention afforded to the relevant stimulus, and the amount of available sensory evidence. We tested memory-impaired patients with bilateral damage to the hippocampus and compared their performance with controls. Despite a modest slowing in response initiation across all task conditions, patients performed similar to controls. Like controls, patients exhibited a tendency to respond faster and more accurately when the motion direction was more probable, the stimulus was better attended, and more sensory evidence was available. Together, these findings demonstrate a robust, hippocampus-independent capacity for learning statistical regularities in the sensory environment in order to improve information processing.

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