Decoding sensorimotor information from somatosensory cortex by flexible epicorticalECoG arrays in unrestrained behaving rats.

Brain-computer interfaces (BCI) are promising for severe neurological conditions and there are ongoing efforts to develop state-of-the-art neural interfaces, hardware, and software tools. We tested the potential of novel reduced graphene oxide (rGO) electrodes implanted epidurally over the hind limb representation of the primary somatosensory (S1) cortex of rats, and compared them to commercial platinum-iridium (Pt-Ir) 16-channel electrodes (active site diameter: 25m).Motor and somatosensory information was decoded offline from microelectrocorticography (ECoG) signals recorded while unrestrained rats performed a simple behavioral task: pressing a lever and the subsequent vibrotactile stimulation of the glabrous skin at three displacement amplitude levels and at two sinusoidal frequencies.

Predicting lever press in a vibrotactile yes/no detection task from S1 cortex of freely behaving rats by µECoG arrays.

Aim Of The Study: Brain-computer interfaces (BCIs) may help patients with severe neurological deficits communicate with the external world. Based on microelectrocorticography (µECoG) data recorded from the primary somatosensory cortex (S1) of unrestrained behaving rats, this study attempts to decode lever presses in a psychophysical detection task by using machine learning algorithms.

Materials And Methods: 16-channel Pt-Ir microelectrode arrays were implanted on the S1 of two rats, and µECoG was recorded during a vibrotactile yes/no detection task.

Measuring tactile sensitivity and mixed-reality-assisted exercise for carpal tunnel syndrome by ultrasound mid-air haptics.

Introduction: Carpal tunnel syndrome (CTS) is the most common nerve entrapment neuropathy, which causes numbness and pain in the thumb, the index and middle fingers and the radial side of the ring finger. Regular hand exercises may improve the symptoms and prevent carpal tunnel surgery. This study applied a novel ultrasonic stimulation method to test tactile sensitivity in CTS and also a mixed-reality-assisted (MR-assisted) exercise program which measured hand movements and provided haptic feedback for rehabilitation.

Real-time vibrotactile pattern generation and identification using discrete event-driven feedback.

This study assesses human identification of vibrotactile patterns by using real-time discrete event-driven feedback. Previously acquired force and bend sensor data from a robotic hand were used to predict movement-type (stationary, flexion, contact, extension, release) and object-type (no object, hard object, soft object) states by using decision tree (DT) algorithms implemented in a field-programmable gate array (FPGA). Six able-bodied humans performed a 2- and 3-step sequential pattern recognition task in which state transitions were signaled as vibrotactile feedback.

Bayesian prediction of psychophysical detection responses from spike activity in the rat sensorimotor cortex.

Decoding of sensorimotor information is essential for brain-computer interfaces (BCIs) as well as in normal functioning organisms. In this study, Bayesian models were developed for the prediction of binary decisions of 10 awake freely-moving male/female rats based on neural activity in a vibrotactile yes/no detection task. The vibrotactile stimuli were 40-Hz sinusoidal displacements (amplitude: 200 µm, duration: 0.

Mechanical Impedance of Rat Glabrous Skin and Its Relation With Skin Morphometry.

The mechanical impedance of intact and epidermis-peeled rat glabrous skin was studied at two sites (digit and sole) and at two frequencies (40 Hz and 250 Hz). The thicknesses of skin layers at the corresponding regions were measured histologically from intact- and peeled-skin samples in every subject. Compared to intact sole skin, digital rat skin has thicker layers and higher mechanical resistance, and it is less stiff.

Distribution and mRNA Expression of nAChRs in the Rat S1 and M1 Cortices After Electrical Stimulation of the Basal Forebrain.

Aim: To study the changes in the distribution of and the transcriptional levels associated with α4- and α7-subtype nicotinic acetylcholine receptors (nAChRs) in the primary somatosensory (S1) and motor (M1) cortices of rats after electrical stimulation of the basal forebrain (BF).

Material And Methods: Immunofluorescence (IF) analyses were performed on brain sections from 20 rats (experimental groups: controls, contralateral, and ipsilateral to BF stimulation). The nAChR receptor complexes were labeled with antibodies and counted (N) in the cortical layers of the hindlimb representation (S1HL), barrel field (S1BF), and M1.

Effect of Remote Masking on Tactile Perception of Electrovibration.

Masking has been used to study human perception of tactile stimuli, including those created by electrovibration on touch screens. Earlier studies have investigated the effect of on-site masking on tactile perception of electrovibration. In this article, we investigated whether it is possible to change the absolute detection threshold and intensity difference threshold of electrovibration at the fingertip of index finger via remote masking, i.

Correction to: Psychophysical detection and learning in freely behaving rats: a probabilistic dynamical model for operant conditioning.

The original version of this article unfortunately has some typographical errors in equations (5), (6), (7), (8), and (12).

Psychophysical detection and learning in freely behaving rats: a probabilistic dynamical model for operant conditioning.

We present a stochastic learning model that combines the essential elements of Hebbian and Rescorla-Wagner theories for operant conditioning. The model was used to predict the behavioral data of rats performing a vibrotactile yes/no detection task. Probabilistic nature of learning was implemented by trial-by-trial variability in the random distributions of associative strengths between the sensory and the response representations.

Effects of basal forebrain stimulation on the vibrotactile responses of neurons from the hindpaw representation in the rat SI cortex.

Basal forebrain (BF) cholinergic system is important for attention and modulates sensory processing. We focused on the hindpaw representation in rat primary somatosensory cortex (S1), which receives inputs related to mechanoreceptors identical to those in human glabrous skin. Spike data were recorded from S1 tactile neurons (n = 87) with (ON condition: 0.

Psychophysical principles of discrete event-driven vibrotactile feedback for prostheses.

We aimed to establish psychophysical principles for non-invasive vibrotactile feedback signalling discrete transition events (e.g., extension to flexion) during use of prostheses, especially for the upper limbs.

Real-Time Performance of a Tactile Neuroprosthesis on Awake Behaving Rats.

With the advancement of electrode and equipment technology, neuroprosthetics have become a promising alternative to partially compensate for the loss of sensorimotor function in amputees and patients with neurological diseases. Cortical neural interfaces are suitable especially for spinal cord injuries and amyotrophic lateral sclerosis. Although considerable success has been achieved in the literature by spike decoding of motor signals from the human brain, somatosensory feedback is essential for better motor control, interaction with objects, and the embodiment of prosthetic devices.

Tactile Masking by Electrovibration.

Future touch screen applications will include multiple tactile stimuli displayed simultaneously or consecutively to single finger or multiple fingers. These applications should be designed by considering human tactile masking mechanism since it is known that presenting one stimulus may interfere with the perception of the other. In this study, we investigate the effect of masking on the tactile perception of electrovibration displayed on touch screens.

Non-NMDA receptor-mediated vibrotactile responses of neurons from the hindpaw representation in the rat SI cortex.

Non-NMDA receptor-mediated vibrotactile responses of neurons from the hindpaw representation were investigated in the rat SI cortex. We recorded single-unit spikes evoked by sinusoidal (duration: 500 ms; frequency: 5, 40, and 250 Hz; amplitude: 100 μm peak-to-peak) stimulation of the glabrous skin. The responses were obtained with microinjection of aCSF (sham), bicuculline, and AMPA near the isolated neurons in anaesthetized rats.

Effect of Waveform on Tactile Perception by Electrovibration Displayed on Touch Screens.

In this study, we investigated the effect of input voltage waveform on our haptic perception of electrovibration on touch screens. Through psychophysical experiments performed with eight subjects, we first measured the detection thresholds of electrovibration stimuli generated by sinusoidal and square voltages at various fundamental frequencies. We observed that the subjects were more sensitive to stimuli generated by square wave voltage than sinusoidal one for frequencies lower than 60 Hz.

Computational Parametric Analysis of the Mechanical Response of Structurally Varying Pacinian Corpuscles.

The Pacinian corpuscle (PC) is a cutaneous mechanoreceptor that senses low-amplitude, high-frequency vibrations. The PC contains a nerve fiber surrounded by alternating layers of solid lamellae and interlamellar fluid, and this structure is hypothesized to contribute to the PC's role as a band-pass filter for vibrations. In this study, we sought to evaluate the relationship between the PC's material and geometric parameters and its response to vibration.

Psychophysical correspondence between vibrotactile intensity and intracortical microstimulation for tactile neuroprostheses in rats.

Objective: Recent studies showed that intracortical microstimulation (ICMS) generates artificial sensations which can be utilized as somatosensory feedback in cortical neuroprostheses. To mimic the natural psychophysical response, ICMS parameters are modulated according to psychometric equivalence functions (PEFs). PEFs match the intensity levels of ICMS and mechanical stimuli, which elicit equal detection probabilities, but they typically do not include the frequency as a control variable.

Effects of passive and active movement on vibrotactile detection thresholds of the Pacinian channel and forward masking.

We investigated the gating effect of passive and active movement on the vibrotactile detection thresholds of the Pacinian (P) psychophysical channel and forward masking. Previous work on gating mostly used electrocutaneous stimulation and did not allow focusing on tactile submodalities. Ten healthy adults participated in our study.

Tactile processing in children and adolescents with obsessive-compulsive disorder.

Many obsessive-compulsive disorder (OCD) patients experience sensory phenomena, such as bodily sensations and "just-right" perceptions accompanying compulsions. We studied tactile processing in OCD by psychophysical experiments targeting the somatosensory cortex. Thirty-two children and adolescents with OCD (8 tic-related, 19 with sensory phenomena (SP)) and their sex- and age-matched controls participated in the study.

A novel vibrotactile system for stimulating the glabrous skin of awake freely behaving rats during operant conditioning.

Background: Rat skin is innervated by mechanoreceptive fibers similar to those in other mammals. Tactile experiments with behaving rats mostly focus on the vibrissal system which does not exist in humans. The aim of this study was to design and implement a novel vibrotactile system to stimulate the glabrous skin of behaving rats during operant conditioning.

Representation of haptic objects during mental rotation in congenital blindness.

The representation of haptic objects by three groups of participants (sighted, blindfolded, and congenitally blind) was studied in a mental-rotation task. Three models were tested. The participants explored a standard object continuously with the left hand and tried to find the mirror object among two alternatives explored sequentially with the right hand.

A device for the functional improvement of lagophthalmos.

A new device was tested on rabbits for the improvement of lagophthalmos, which causes dryness and irritation of the eye and may cause blindness if untreated. In the presented study, 14 rabbits were injected with local anesthetic to induce temporary facial palsy leading to lagophthalmos on one side. To provide functionality to the upper eyelids, ferromagnetic steel plates were either implanted within the eyelid or taped on the eyelid surface.

Relationship between vibrotactile detection threshold in the Pacinian channel and complex mechanical modulus of the human glabrous skin.

The goal of this study was to investigate the relationship between the psychophysical vibrotactile thresholds of the Pacinian (P) channel and the mechanical properties of the skin at the fingertip. Seven healthy adult subjects (age: 23-30) participated in the study. The mechanical stimuli were 250-Hz sinusoidal bursts and applied with cylindrical contactor probes of radii 1, 2, and 3.

Asymmetric response properties of rapidly adapting mechanoreceptive fibers in the rat glabrous skin.

Previous histological and neurophysiological studies have shown that the innervation density of rapidly adapting (RA) mechanoreceptive fibers increases towards the fingertip. Since the psychophysical detection threshold depends on the contribution of several RA fibers, a high innervation density would imply lower thresholds. However, our previous human study showed that psychophysical detection thresholds for the Non-Pacinian I channel mediated by RA fibers do not improve towards the fingertip.