Receipt of reward leads to altered estimation of effort

Effort and reward jointly shape many human decisions. Errors in predicting the required effort needed for a task can lead to suboptimal behavior. Here, we show that effort estimations can be biased when retrospectively re-estimated following receipt of a rewarding outcome. These biases depend on the contingency between reward and task difficulty, and are stronger for highly contingent rewards. Strikingly the observed pattern accords with predictions from Bayesian cue integration, indicating humans deploy an adaptive and rational strategy to deal with inconsistencies between the efforts they expend and the ensuing rewards

The role of attention in figure-ground segregation in areas V1 and V4 of the visual cortex

SummaryOur visual system segments images into objects and background. Figure-ground segregation relies on the detection of feature discontinuities that signal boundaries between the figures and the background and on a complementary region-filling process that groups together image regions with similar features. The neuronal mechanisms for these processes are not well understood and it is unknown how they depend on visual attention. We measured neuronal activity in V1 and V4 in a task where monkeys either made an eye movement to texture-defined figures or ignored them. V1 activity predicted the timing and the direction of the saccade if the figures were task relevant. We found that boundary detection is an early process that depends little on attention, whereas region filling occurs later and is facilitated by visual attention, which acts in an object-based manner. Our findings are explained by a model with local, bottom-up computations for boundary detection and feedback processing for region filling

Encoding of Dynamic Visual Stimuli by Primate Area MT Neurons

Neural stimulus selectivity is thought to be optimized for the representation of real-world stimuli. Neural coding properties, therefore, may adapt to different environments. Here, we address the question if tuning curves depend on the statistics of visual stimuli. This is done by studying the directional tuning of macaque area MT neurons exposed to dynamic motion stimuli of two different direction progression statistics. Despite an apparent difference of tuning curves across stimulus conditions, our results support the view that the underlying encoding system is robust and subject to only restricted malleability by stimulus statistics. Key words: directional tuning, stimulus statistics, area MT, reverse correlation

Stimulus Representation in Rat Primary Visual Cortex: Multi-Electrode Recordings With Micromachined Silicon Probes and Estimation Theory

The study of neural population codes relies on massively parallel recordings in combination with theoretically motivated analysis tools. We applied two multi-site recording techniques to record from cells throughout cortical depth in a minimally invasive way. The feasibility of such experiments in area 17 of the anesthetized rat is demonstrated. Bayesian reconstruction and the interpretative framework of Fisher information are introduced. We demonstrate applicability and usefulness of Bayesian stimulus reconstruction and show that even small numbers of neurons can yield a high degree of representational accuracy under favorable conditions. Results are discussed and future lines of research outlined

Visual working memory organization is subject to top-down control

The limited capacity of visual working memory (VWM) can be maximized by combining multiple features into a single representation through grouping principles such as connection, proximity, and similarity. In this study, we sought to understand how VWM organizes information by investigating how connection and similarity cues are used either alone or in the presence of another grouping cue. Furthermore, we examined whether the use of one cue over another is within volitional control. Participants remembered displays of objects that contained no grouping cues, connection cues only, similarity cues only, or both connection and similarity cues. We found that it is possible to use either connection or similarity cues, although connection cues tend to dominate if cues are in conflict with one another. However, it is possible to flexibly use either similarity or connection cues if both are present, depending on the task goals