Does Vibrotactile Stimulation of the Auricular Vagus Nerve Enhance Working Memory? A Behavioral and Physiological Investigation.

Background: Working memory is essential to a wide range of cognitive functions and activities. Transcutaneous auricular VNS (taVNS) is a promising method to improve working memory performance. However, the feasibility and scalability of electrical stimulation are constrained by several limitations, such as auricular discomfort and inconsistent electrical contact. Objective: We aimed to develop a novel and practical method, vibrotactile taVNS, to improve working memory. Further, we investigated its effects on arousal, measured by skin conductance and pupil diameter. Method: This study included 20 healthy participants. Behavioral response, skin conductance, and eye tracking data were concurrently recorded while the participants performed N-back tasks under three conditions: vibrotactile taVNS delivered to the cymba concha, earlobe (sham control), and no stimulation (baseline control). Results: In 4-back tasks, which demand maximal working memory capacity, active vibrotactile taVNS significantly improved the performance metric d ' compared to the baseline but not to the sham. Moreover, we found that the reduction rate of d ' with increasing task difficulty was significantly smaller during vibrotactile taVNS sessions than in both baseline and sham conditions. Arousal, measured as skin conductance and pupil diameter, declined over the course of the tasks. Vibrotactile taVNS rescued this arousal decline, leading to arousal levels corresponding to optimal working memory levels. Moreover, pupil diameter and skin conductance level were higher during high-cognitive-load tasks when vibrotactile taVNS was delivered to the concha compared to baseline and sham. Conclusion: Our findings suggest that vibrotactile taVNS modulates the arousal pathway and could be a potential intervention for enhancing working memory. Highlights: Vibrotactile stimulation of the auricular vagus nerve increases general arousal.Vibrotactile stimulation of the auricular vagus nerve mitigates arousal decreases as subjects continuously perform working memory tasks.6 Hz Vibrotactile auricular vagus nerve stimulation is a potential intervention for enhancing working memory performance.

Does vibrotactile stimulation of the auricular vagus nerve enhance working memory? A behavioral and physiological investigation.

BACKGROUND: Working memory is essential to a wide range of cognitive functions and activities. Transcutaneous auricular vagus nerve stimulation (taVNS) is a promising method to improve working memory performance. However, the feasibility and scalability of electrical stimulation are constrained by several limitations, such as auricular discomfort and inconsistent electrical contact. OBJECTIVE: We aimed to develop a novel and practical method, vibrotactile taVNS, to improve working memory. Further, we investigated its effects on arousal, measured by skin conductance and pupil diameter. METHOD: This study included 20 healthy participants. Behavioral response, skin conductance, and eye tracking data were concurrently recorded while the participants performed N-back tasks under three conditions: vibrotactile taVNS delivered to the cymba concha, earlobe (sham control), and no stimulation (baseline control). RESULTS: In 4-back tasks, which demand maximal working memory capacity, active vibrotactile taVNS significantly improved the performance metric d' compared to the baseline but not to the sham. Moreover, we found that the reduction rate of d' with increasing task difficulty was significantly smaller during vibrotactile taVNS sessions than in both baseline and sham conditions. Arousal, measured as skin conductance and pupil diameter, declined over the course of the tasks. Vibrotactile taVNS rescued this arousal decline, leading to arousal levels corresponding to optimal working memory levels. Moreover, pupil diameter and skin conductance level were higher during high-cognitive-load tasks when vibrotactile taVNS was delivered to the concha compared to baseline and sham. CONCLUSION: Our findings suggest that vibrotactile taVNS modulates the arousal pathway and could be a potential intervention for enhancing working memory.

A Protactile-Inspired Wearable Haptic Device for Capturing the Core Functions of Communication.

In this article, a novel wearable haptic device, to be worn on the hand and forearm, is introduced. Using the modalities of vibration, pressure, and heat application, the device attempts to replicate four core components of communication. The four components - co-presence, phatic communication, back-channeling, and direction giving - are simulated through haptic profiles individually unique to a section or combined as an encompassing system of the device. This paper evaluates the performance of the device through three testing phases with sighted-hearing and DeafBlind individuals. Results indicate that a strong majority of the tested haptic profiles show statistical significance in replication between individuals. This article is unique in its collaboration with the protactile DeafBlind community, individuals who communicate solely through touch, by furthering understanding on how to generate intuitive tactile profiles in wearable haptic devices.

Comparing Haptic Pattern Matching on Tablets and Phones: Large Screens Are Not Necessarily Better.

Touchscreen-based, multimodal graphics represent an area of increasing research in digital access for individuals with blindness or visual impairments; yet, little empirical research on the effects of screen size on graphical exploration exists. This work probes if and when more screen area is necessary in supporting a pattern-matching task. PURPOSE: Larger touchscreens are thought to have distinct benefit over smaller touchscreens for the amount of space available to convey graphical information nonvisually. The current study investigates two questions: (1) Do screen size and grid density impact a user's accuracy on pattern-matching tasks? (2) Do screen size and grid density impact a user's time on task? METHODS: Fourteen blind and visually impaired individuals were given a pattern-matching task to complete on either a 10.5-in tablet or a 5.1-in phone. The patterns consisted of five vibrating targets imposed on sonified grids that varied in density (higher density = more grid squares). At test, participants compared the touchscreen pattern with a group of physical, embossed patterns and selected the matching pattern. Participants were evaluated on time exploring the pattern on the device and their pattern-matching accuracy. Multiple and logistic regressions were performed on the data. RESULTS: Device size, grid density, and age had no statistically significant effects on the model of pattern-matching accuracy. However, device size, grid density, and age had significant effects on the model for grid exploration. Using the phone, exploring low-density grids, and being older were indicative of faster exploration time. CONCLUSIONS: A trade-off of time and accuracy exists between devices that seems to be task dependent. Users may find a tablet most useful in situations where the accuracy of graphic interpretation is important and is not limited by time. Smaller screen sizes afforded comparable accuracy performance to tablets and were faster to explore overall.

Wireless insufflation of the gastrointestinal tract.

Despite clear patient experience advantages, low specificity rates have thus far prevented swallowable capsule endoscopes from replacing traditional endoscopy for diagnosis of colon disease. One explanation for this is that capsule endoscopes lack the ability to provide insufflation, which traditional endoscopes use to distend the intestine for a clear view of the internal wall. To provide a means of insufflation from a wireless capsule platform, in this paper we use biocompatible effervescent chemical reactions to convert liquids and powders carried onboard a capsule into gas. We experimentally evaluate the quantity of gas needed to enhance capsule visualization and locomotion, and determine how much gas can be generated from a given volume of reactants. These experiments motivate the design of a wireless insufflation capsule, which is evaluated in ex vivo experiments. These experiments illustrate the feasibility of enhancing visualization and locomotion of endoscopic capsules through wireless insufflation.