Search results for "Photic stimulation"
showing 10 items of 307 documents
Action expertise reduces brain activity for audiovisual matching actions: An fMRI study with expert drummers
2011
When we observe someone perform a familiar action, we can usually predict what kind of sound that action will produce. Musical actions are over-experienced by musicians and not by non-musicians, and thus offer a unique way to examine how action expertise affects brain processes when the predictability of the produced sound is manipulated. We used functional magnetic resonance imaging to scan 11 drummers and 11 age- and gender-matched novices who made judgments on point-light drumming movements presented with sound. In Experiment 1, sound was synchronized or desynchronized with drumming strikes, while in Experiment 2 sound was always synchronized, but the natural covariation between sound in…
Multisensory integration of drumming actions: musical expertise affects perceived audiovisual asynchrony
2009
We investigated the effect of musical expertise on sensitivity to asynchrony for drumming point-light displays, which varied in their physical characteristics (Experiment 1) or in their degree of audiovisual congruency (Experiment 2). In Experiment 1, 21 repetitions of three tempos x three accents x nine audiovisual delays were presented to four jazz drummers and four novices. In Experiment 2, ten repetitions of two audiovisual incongruency conditions x nine audiovisual delays were presented to 13 drummers and 13 novices. Participants gave forced-choice judgments of audiovisual synchrony. The results of Experiment 1 show an enhancement in experts' ability to detect asynchrony, especially fo…
Detection performance of normal cats and those lacking areas 17 and 18: a behavioral approach to analyse pattern recognition deficits.
1986
The ability of cats to discriminate between two geometrical outline patterns in the presence of superimposed Gaussian visual noise was tested before and after bilateral removal of cortical area 17 and parts of area 18. The detection probability PD was measured as a function of the signal-to-noise ratio for the parameters: noise bandwidth, spatial frequency content and rate of movement of patterns. In both normal and lesioned cats a broadband noise was found to be most effective in masking the large patterns while two other types of noise, a medium frequency noise and a high frequency noise had little or no masking effect. For recognition of the smaller patterns in normal cats the medium fre…
V1 non-linear properties emerge from local-to-global non-linear ICA
2006
It has been argued that the aim of non-linearities in different visual and auditory mechanisms may be to remove the relations between the coefficients of the signal after global linear ICA-like stages. Specifically, in Schwartz and Simoncelli (2001), it was shown that masking effects are reproduced by fitting the parameters of a particular non-linearity in order to remove the dependencies between the energy of wavelet coefficients. In this work, we present a different result that supports the same efficient encoding hypothesis. However, this result is more general because, instead of assuming any specific functional form for the non-linearity, we show that by using an unconstrained approach…
Photo-acoustic excitation and optical detection of fundamental flexural guided wave in coated bone phantoms.
2013
Abstract Photo-acoustic (PA) imaging was combined with skeletal quantitative ultrasound (QUS) for assessment of human long bones. This approach permitted low-frequency excitation and detection of ultrasound so as to efficiently receive the thickness-sensitive fundamental flexural guided wave (FFGW) through a coating of soft tissue. The method was tested on seven axisymmetric bone phantoms, whose 1- to 5-mm wall thickness and 16-mm diameter mimicked those of the human radius. Phantoms were made of a composite material and coated with a 2.5- to 7.5-mm layer of soft material that mimicked soft tissue. Ultrasound was excited with a pulsed Nd:YAG laser at 1064-nm wavelength and received on the s…
Functional correlate and delineated connectivity pattern of human motion aftereffect responses substantiate a subjacent visual-vestibular interaction.
2018
The visual motion aftereffect (MAE) is the most prominent aftereffect in the visual system. Regarding its function, psychophysical studies suggest its function to be a form of sensory error correction, possibly also triggered by incongruent visual-vestibular stimulation. Several observational imaging experiments have deducted an essential role for region MT+ in the perception of a visual MAE but not provided conclusive evidence. Potential confounders with the MAE such as ocular motor performance, attention, and vection sensations have also never been controlled for. Aim of this neuroimaging study was to delineate the neural correlates of MAE and its subjacent functional connectivity pattern…
The columnar gene vnd is required for tritocerebral neuromere formation during embryonic brain development of Drosophila.
2006
International audience; In Drosophila, evolutionarily conserved transcription factors are required for the specification of neural lineages along the anteroposterior and dorsoventral axes, such as Hox genes for anteroposterior and columnar genes for dorsoventral patterning. In this report, we analyse the role of the columnar patterning gene ventral nervous system defective (vnd) in embryonic brain development. Expression of vnd is observed in specific subsets of cells in all brain neuromeres. Loss-of-function analysis focussed on the tritocerebrum shows that inactivation of vnd results in regionalized axonal patterning defects, which are comparable with the brain phenotype caused by mutatio…
Mechanism underlying the inhibitory sidebands in the receptive field of simple striate cells of the cat: pure on/off antagonism only or true inhibiti…
1985
The intrinsic organization of the receptive fields of simple striate cells revealed by moving stimuli is much more complex than could have been suspected from the use of stationary ones. There is, in fact, a small excitatory region centrally located in these receptive fields and an inhibitory region encompassing the whole excitatory component. These inhibitory regions or “inhibitory sidebands”, were identified by stimulating the cells with bars of light against anartificial background discharge produced by repeated asynchronous stimulation of the excitatory component of the cell's receptive field. For a long time' these inhibitory sidebands have been accounted for on the basis of the recept…
Study on the transient characteristic in the human visual system using masking experiments
1979
In this paper the visual masking effect is interpreted on the basic of the transient characteristic in two dimensional neuronal networks. The study investigates the suitability of the effect for use as a measurement method. It is shown that the stimulus distribution in space can be scanned at different points in time and that various dynamic characteristic values of the system can be measured.
Neuronal network characteristics in the cat superior colliculus
1977
The system theoretical description of the superficial layers of neurons in the cat's superior colliculus is based on homogeneous linear space-time filters. The most important neurophysiological findings on the superior colliculus are simulated on the digital computer by generating suitable coupling functions and matching the space and time parameters. It is shown that the neurophysiological measurements can be interpreted by varying a few system parameters. The curves of velocity dependent responses, direction specificity and the effects of the colliculus specific surround are examined in particular. Computer simulation shows that such a surround can evaluate small moving stimuli differentl…