External location of touch is constructed post-hoc based on limb choice

When humans indicate on which hand a tactile stimulus occurred, they often err when their hands are crossed. This finding seemingly supports the view that the automatically determined touch location in external space affects limb assignment: the crossed right hand is localized in left space, and this conflict presumably provokes hand assignment errors. Here, participants judged on which hand the first of two stimuli, presented during a bimanual movement, had occurred, and then indicated its external location by a reach-to-point movement. When participants incorrectly chose the hand stimulated second, they pointed to where that hand had been at the correct, first time point, though no stimulus had occurred at that location. This behavior suggests that stimulus localization depended on hand assignment, not vice versa. It is, thus, incompatible with the notion of automatic computation of external stimulus location upon occurrence. Instead, humans construct external touch location post-hoc and on demand.

Semantic Localization System for Robots at Large Indoor Environments Based on Environmental Stimuli

In this paper, we present a new procedure to solve the global localization of mobile robots called Environmental Stimulus Localization (ESL). We propose that the presence of common facts on the environment around the robot can be considered as stimuli for the procedure. The robust performance of our approach is supported by two concurrent particle filters. A primary particle filter estimates and tracks the robot position, while a secondary filter is fired by environmental stimuli, helps to reduce the influence of measurement errors and allows an earlier recovery from localization failures. We have successfully used this method in a 5000 m 2 real indoor environment using as inputs the available environment information from a Geographical Information System (GIS) map, the robot’s odometry and the output of an algorithm for the perception of facts from the environment. We present a case study and the result of different tests, showing the performance of our method under the influence of errors in real applications.

Functional relevance of dual olfactory bulb in olfactory coding

Bilateral convergence of external stimuli is a common feature of vertebrate sensory systems. This convergence of inputs from the bilateral receptive fields allows higher order sensory perception, such as depth perception in the vertebrate visual system and stimulus localization in the auditory system. The functional role of such bilateral convergence in the olfactory system is mostly unknown. To test whether each olfactory bulb contributes a separate piece of olfactory information, and whether information from the bilateral olfactory bulb is integrated, we synchronized the activation of olfactory bulbs with blue light in mice expressing channelrhodopsin in the olfactory sensory neurons and behaviorally assessed the relevance of dual olfactory bulb in olfactory perception. Our findings suggest that each olfactory bulb contributes separate components of olfactory information and mice integrate the olfactory information from each olfactory bulb to identify an olfactory stimulus.Significance statementIdentifying an odor is the first step in olfactory coding, as it is critical for the survival of most animals. Previous studies have shown that bilateral olfactory bulbs help rodents to localize the odor source and navigate accordingly. But It is still unclear whether the bilateral olfactory information plays any role in determining odor identity. Here for the first time, using optogenetics and behavioral experiments, we demonstrate that each olfactory bulb provides distinct olfactory information, and rodents integrate information from the two bulbs to identify an odor.

External location of touch is constructed post-hoc based on limb choice

When humans indicate on which hand a tactile stimulus occurred, they often err when their hands are crossed. This finding seemingly supports the view that the automatically determined touch location in external space affects limb assignment: the crossed right hand is localized in left space, and this conflict presumably provokes hand assignment errors. Here, participants judged on which hand the first of two stimuli, presented during a bimanual movement, had occurred, and then indicated its external location by a reach-to-point movement. When participants incorrectly chose the hand stimulated second, they pointed to where that hand had been at the correct, first time point, though no stimulus had occurred at that location. This behavior suggests that stimulus localization depended on hand assignment, not vice versa. It is, thus, incompatible with the notion of automatic computation of external stimulus location upon occurrence. Instead, humans construct external touch location post-hoc and on demand.

Practice improves peri-saccadic shape judgment but does not diminish target mislocalization

Visual sensitivity is markedly reduced during an eye movement. Peri-saccadic vision is also characterized by a mislocalization of the briefly presented stimulus closer to the saccadic target. These features are commonly viewed as obligatory elements of peri-saccadic vision. However, practice improves performance in many perceptual tasks performed at threshold conditions. We wondered if this could also be the case with peri-saccadic perception. To test this, we used a paradigm in which subjects reported the orientation (or location) of an ellipse briefly presented during a saccade. Practice on peri-saccadic orientation discrimination led to long-lasting gains in that task but did not alter the classical mislocalization of the visual stimulus. Shape discrimination gains were largely generalized to other untrained conditions when the same stimuli were used (discrimination during a saccade in the opposite direction or at a different stimulus location than previously trained). However, performance dropped to baseline level when participants shifted to a novel Vernier discrimination task under identical saccade conditions. Furthermore, practice on the location task did not induce better stimulus localization or discrimination. These results suggest that the limited visual information available during a saccade may be better used with practice, possibly by focusing attention on the specific target features or a better readout of the available information. Saccadic mislocalization, by contrast, is robust and resistant to top-down modulations, suggesting that it involves an automatic process triggered by the upcoming execution of a saccade (e.g., an efference copy signal).

Mechanotransduction of Multi-Hair Droplet Arrays

Early embodiments of droplet interface bilayer (DIB)-based hair cell sensors demonstrated the capability of sensing discrete and continuous perturbations, including single flicks and constant airflow, respectively, of a hair structure that is held in close proximity to a single lipid membrane. In those studies, the use of a single bilayer formed between a pair of droplets provided the necessary environment for studying the physical mechanism of mechanotransduction of a membrane-based sensor as well as the sensitivity and directionality of the assembly. More recently, we showed that additional lipid-coated droplets could be connected in series to form multi-bilayer arrays. Measurements of bilayer current through each interface demonstrated that perturbation of the hair creates a vibration that propagates across several droplets, allowing for the additional interfaces to also sense the perturbation. Depending on the location of the hair in the droplet array, these sensing currents can occur in-phase with one another, allowing for a total sensing current to be easily summed. Two important remaining questions about multi-bilayer arrays include: 1) How is signal propagation affected by the configuration of droplets in the array? 2) How does perturbation of multiple hair structures affect signal propagation and sensing currents in a droplet-array? To study these questions, we form linear series and L-shaped arrays of DIBs where each droplet is instrumented with a sensing electrode. Our experiments show that the motion of the perturbed hair can be transduced by up to three membranes away from the hair and that a change in the orientation of successive interfaces does not significantly affect the propagation of vibrational energy. Separately, experiments on serial arrays with multiple hairs indicate that a second, unperturbed hair does not affect bilayer currents generated by the perturbed hair and that hairs of varying length can add frequency selectivity and stimulus localization capability to multi-bilayer sensors.