Search results for "Sensory system"

Mapping of the human visual cortex using image-guided transcranial magnetic stimulation

2002

We describe a protocol using transcranial magnetic stimulation (TMS) to systematically map the visual sensations induced by focal and non-invasive stimulation of the human occipital cortex. TMS is applied with a figure of eight coil to 28 positions arranged in a 2x2-cm grid over the occipital area. A digitizing tablet connected to a PC computer running customized software, and audio and video recording are used for detailed and accurate data collection and analysis of evoked phosphenes. A frameless image-guided neuronavigational device is used to describe the position of the actual sites of the stimulation coils relative to the cortical surface. Our results show that TMS is able to elicit p…

Binocular Vision in Patients with Multiple Sclerosis.

2021

Amparo Gil-Casas,1,2 David P Piñero-Llorens,2 Ainhoa Molina-Martin2 1Clínica Optométrica, Fundació Lluís Alcanyís, University of Valencia, Valencia, Spain; 2Optics and Visual Perception Group (GOPV), Department of Optics, Pharmacology, and Anatomy, University of Alicante, Alicante, SpainCorrespondence: Ainhoa Molina-MartinDepartment of Optics, Pharmacology, and Anatomy, University of Alicante, Carretera San Vicente del Raspeig, San Vicente del Raspeig, 03690, Alicante, SpainTel +34 965 903-400Email ainhoa.molina@ua.esPurpose: Oculomotor disorders have been reported in multiple sclerosis (MS) in up to 80% of cases. There have …

Quantifying Intermodal Distraction by Emotion During Math Performance: An Electrophysiological Approach

2019

Emotionally engaging stimuli are powerful competitors for limited attention capacity. In the cognitive neuroscience laboratory, the presence of task-irrelevant emotionally arousing visual distractors prompts decreased performance and attenuated brain responses measured in concurrent visual tasks. The extent to which distraction effects occur across different sensory modalities is not yet established, however. Here, we examined the extent and time course of competition between a naturalistic distractor sound and a visual task stimulus, using dense-array electroencephalography (EEG) recordings from 20 college students. Steady-state visual evoked potentials (ssVEPs) were quantified from EEG, e…

Patients with Minimal Hepatic Encephalopathy Show Altered Thermal Sensitivity and Autonomic Function

2021

Cirrhotic patients may experience alterations in the peripheral nervous system and in somatosensory perception. Impairment of the somatosensory system could contribute to cognitive and motor alterations characteristic of minimal hepatic encephalopathy (MHE), which affects up to 40% of cirrhotic patients. We assessed the relationship between MHE and alterations in thermal, vibration, and/or heat pain sensitivity in 58 cirrhotic patients (38 without and 20 with MHE according to Psychometric Hepatic Encephalopathy Score) and 39 controls. All participants underwent attention and coordination tests, a nerve conduction study, autonomic function testing, and evaluation of sensory thresholds (vibra…

2017

The mere presence of a depiction of eyes can elicit a sense of being watched in the perceiver. To this date, the factors affecting the intensity of this sense of being watched, however, have not been investigated. In the present experiment, we tested the impact of two potentially relevant variables: arousal (manipulated using specific musical pieces) and duration of the perceptual episode (manipulated using presentation times of 200 ms and 10 s, respectively). We asked participants to report how intensely they felt being watched while we exposed them to various observation cues ranging from human eyes to surveillance cameras. We found that, on average, reported intensities were higher if pa…

Somatosensory Illusions Elicited by Sham Electromagnetic Field Exposure: Experimental Evidence for a Predictive Processing Account of Somatic Symptom…

2020

OBJECTIVE According to the predictive processing theory of somatic symptom generation, body sensations are determined by somatosensory input and central nervous predictions about this input. We examined how expectations shape predictions and consequently bodily perceptions in a task eliciting illusory sensations as laboratory analogue of medically unexplained symptoms. METHODS Using the framework of signal detection theory, the influence of sham Wi-Fi on response bias (c) and somatosensory sensitivity (d') for tactile stimuli was examined using the somatic signal detection task (SSDT). A healthy student sample (n = 83) completed the SSDT twice (sham Wi-Fi on/off) in a randomized order after…

Effect of Different Display Types on Vection and Its Interaction With Motion Direction and Field Dependence

2017

Illusory self-motion (vection) can be generated by visual stimulation. The purpose of the present study was to compare behavioral vection measures including intensity ratings, duration, and onset time across different visual display types. Participants were exposed to a pattern of alternating black-and-white horizontal or vertical bars that moved either in vertical or horizontal direction, respectively. Stimuli were presented on four types of displays in randomized order: (a) large field of view dome projection, (b) combination of three computer screens, (c) single computer screen, (d) large field of view flat projection screen. A Computer Rod and Frame Test was used to measure field depen…

Choroidal filling pattern during a hypotensive crisis

1987

Observation d'une jeune femme de 18 ans atteinte de dystrophie progressive des cones et bâtonnets et ayant presente une crise d'hypotension arterielle au cours d'une angiographie fluoresceinique

Efficacy of diclofenac eyedrops in preventing postoperative inflammation and long-term cystoid macular edema.

1997

Abstract Purpose: To compare the efficacy and tolerance of diclofenac 0.1 % eyedrops with a regimen that included a brief course of steroids in the treatment of postoperative inflammation after extracapsular cataract surgery and posterior chamber intraocular lens implantation. A second objective was to compare the efficacy of diclofenac 0.1% eyedrops in the same patients and control group in preventing cystoid macular edema (CME). Setting: Eight university/hospital centers and one company in Italy. Methods: The multicenter, controlled, randomized, prospective, double-blind study included 281 patients. All were evaluated at baseline, at surgery, and after 1, 5, 36, 67, and 140 days. Postoper…

Role of  1-Adrenoceptor Subtypes in Pupil Dilation Studied With Gene-Targeted Mice

2014

PURPOSE The α₁A-adrenoceptor (α₁A-AR) subtype was suggested to mediate contraction and trophic effects in the iris dilator muscle, and thus its pharmacological blockade may be involved in intraoperative floppy iris syndrome. We tested the hypothesis that the α₁A-AR mediates pupil dilation and trophic effects in the mouse iris. METHODS The α₁-AR subtype mRNA expression was quantified in iris tissue by real-time PCR. To assess the role of individual α₁-ARs for mediating pupil dilation, the α₁-AR agonist phenylephrine was topically applied to the ocular surface of mice deficient in one of the three α₁-AR subtypes (α₁A-AR(-/-), α₁B-AR(-/-), α₁D-AR(-/-), respectively) and wild-type controls. Cha…