Search results for "Stimulus"
showing 10 items of 555 documents
Visual mismatch negativity (vMMN): A review and meta-analysis of studies in psychiatric and neurological disorders
2016
The visual mismatch negativity (vMMN) response is an event-related potential (ERP) component, which is automatically elicited by events that violate predictions based on prior events. VMMN experiments use visual stimulus repetition to induce predictions, and vMMN is obtained by subtracting the response to rare unpredicted stimuli from those to frequent stimuli. One increasingly popular interpretation of the mismatch response postulates that vMMN, similar to its auditory counterpart (aMMN), represents a prediction error response generated by cortical mechanisms forming probabilistic representations of sensory signals. Here we discuss the physiological and theoretical basis of vMMN and review…
Transcranial direct current stimulation preconditioning modulates the effect of high-frequency repetitive transcranial magnetic stimulation in the hu…
2012
Experimental studies emphasize the importance of homeostatic plasticity as a mean of stabilizing the properties of neural circuits. In the present work we combined two techniques able to produce short-term (5-Hz repetitive transcranial magnetic stimulation, rTMS) and long-term (transcranial direct current stimulation, tDCS) effects on corticospinal excitability to evaluate whether and how the effects of 5-Hz rTMS can be tuned by tDCS preconditioning. Twelve healthy subjects participated in the study. Brief trains of 5-Hz rTMS were applied to the primary motor cortex at an intensity of 120% of the resting motor threshold, with recording of the electromyograph traces evoked by each stimulus o…
Accommodative Stimulus-Response Curve with Emoji Symbols
2017
Purpose. To evaluate the static measurement of the accommodative stimulus-response curve with emoji symbols. Methods. The accommodative stimulus-response curve was measured in 18 subjects using a Hartmann-Shack sensor to obtain the objective accommodative response from the Zernike defocus term. Measurements were acquired at different accommodative demands, from 0 to 3 D with a step of 0.5 D. Detailed and nondetailed emoji targets were used with two different sizes, corresponding to the two most common visual angles used in smartphones. Results. A regression analysis was performed to fit the mean results obtained for each target. The determination coefficient was R2≥0.988 for all targets. Fo…
Specific transfer effects following variable priority dual-task training in older adults
2016
International audience; Purpose: Past divided attention training studies in older adults have suggested that variable priority training (VPT) tends to show larger improvement than fixed priority training (FPT). However, it remains unclear whether VPT leads to larger transfer effects. Methods: In this study, eighty-three older adults aged between 55 and 65 received five 1-hour sessions of VPT, FPT or of an active placebo. VPT and FPT subjects trained on a complex dual-task condition with variable stimulus timings in order to promote more flexible and self-guided strategies with regard to attentional priority devoted to the concurrent tasks. Real-time individualized feedback was provided to e…
Rhythmic variations in reaction times and evoked potentials
1995
The present work aimed to assess the existence of a regular ultradian cyclicity underlying the variations in amplitude of the N1-P2 component of acoustic EP during a relatively long recording session and investigate its relationship with behavioral measure as RT to the same stimulus. 128 tones were presented to each subject; 128 RTs and the associated EPs to target stimuli were recorded. N1-P2 amplitude has been measured at a single trial level through Woody adaptive filter modified by Wastell. Results showed that there are ultradian rhythmic variations of N1-P2 and RT, with a periodicity from about 5 to 40 min and these variations have similar patterns in the two measures in most of the su…
Ultradian rhythms in avoidance behavior of DBA mice
1994
This study investigates ultradian rhythm in avoidance behavior of mice, which may constitute a basic rest activity cycle (BRAC). Reaction times (RTs) of an avoidance response to a visual warning stimulus that preceded an electric shock were measured by the use of a computer-controlled shuttle box. The male naive DBA mice were brought to a criterion of 98% correct responses in numerous training sessions. For each subject, all the temporal sequences of the RTs in the trials following achievement of the criterion were examined with discrete Fourier transform. Periodograms were obtained from three sessions for each of the two animals in the first experiment and from 15 subjects in the second ex…
Do children with overweight respond faster to food-related words?
2020
Abstract Overweight in childhood is a risk factor in developing obesity as an adult, thus having severe consequences on the individuals’ physical health and psychological well-being. Therefore, studying the cognitive and emotional processes that sustain overweight is essential not only at a theoretical level but also to develop effective interventions. In the present experiment, we examined whether children with overweight respond faster to food-related than non-food-related words in a word recognition task: lexical decision. The participants were 24 children diagnosed with exogenous overweight and 24 children with a healthy weight. The stimulus list included positively valenced food-relate…
Evidence of a contralateral motor influence on reciprocal inhibition in man
1992
The role of contralateral movement on both H reflex and reciprocal inhibition was studied. In normal men H reflex was induced by median nerve stimulation. Reciprocal inhibition was achieved through stimulation of the antagonist radial nerve. On this basis the effects of contralateral arm movement were analized. Furthermore the putative influence of exteroceptive origin was also verified by means of digit stimulation. Results showed that contralateral arm movement did not affect H reflex amplitude; on the contrary, it was able to enhance reciprocal inhibition induced by extensors on flexors. Study of cutaneous afferents demonstrated that contralateral digit stimulation failed to elicit modif…
Exploring the reciprocal modulation of time and space in dancers and non-dancers.
2014
We explored whether time and space representations modulate each other in subjects that are trained to integrate time and space dimensions, i.e., professional dancers. A group of dancers, and one of non-dancers, underwent two different tasks employing identical stimuli. A first static central line could last one of three possible durations and could have one of three possible lengths. A second growing line appeared from the left or right of the screen and grew up toward the opposite direction at constant velocity. In the Spatial task, subjects encoded the length of the static line and stopped the growing line when it had reached half the length of the static one, regardless of time travel. …
Influence of appearance-related TV commercials on body image state.
2008
This study investigates the influence of media exposure on body image state in eating-disordered (ED) patients. The attitudinal and perceptual components of body image are assessed, as well as any associations with dysfunctional cognitions and behavioral consequences. Twenty-five ED patients and 25 non-ED controls (ND) viewed commercials either featuring appearance (AC; 5 min) or not featuring appearance (NC; 5 min). Both perceptual and attitudinal body image components changed markedly after the AC condition for ED patients, compared with the ND group and NC condition. Cognitions referring to dietary restraint and internalization/social comparison also changed significantly in ED patients…