Neural basis of identity information extraction from noisy face images

Previous research has made significant progress in identifying the neural basis of the remarkably efficient and seemingly effortless face perception in humans. However, the neural processes that enable the extraction of facial information under challenging conditions when face images are noisy and deteriorated remains poorly understood. Here we investigated the neural processes underlying the extraction of identity information from noisy face images using fMRI. For each participant, we measured (1) face-identity discrimination performance outside the scanner, (2) visual cortical fMRI responses for intact and phase-randomized face stimuli, and (3) intrinsic functional connectivity using resting-state fMRI. Our whole-brain analysis showed that the presence of noise led to reduced and increased fMRI responses in the mid-fusiform gyrus and the lateral occipital cortex, respectively. Furthermore, the noise-induced modulation of the fMRI responses in the right face-selective fusiform face area (FFA) was closely associated with individual differences in the identity discrimination performance of noisy faces: smaller decrease of the fMRI responses was accompanied by better identity discrimination. The results also revealed that the strength of the intrinsic functional connectivity within the visual cortical network composed of bilateral FFA and bilateral object-selective lateral occipital cortex (LOC) predicted the participants' ability to discriminate the identity of noisy face images. These results imply that perception of facial identity in the case of noisy face images is subserved by neural computations within the right FFA as well as a re-entrant processing loop involving bilateral FFA and LOC. © 2015 the authors

Amblyopic deficit beyond the fovea : delayed and variable single-trial ERP response latencies, but unaltered amplitudes

Purpose. Amblyopia was first described as a deficit of central vision. However, it has long been debated whether this dysfunction is limited to the fovea or whether extrafoveal vision is also affected, as studies concerning the latter are equivocal. The purpose of the study was to resolve this issue. Methods. We investigated the amblyopic effect on event-related potentials (ERPs) with foveal and perifoveal stimuli, either matched in size based on cortical magnification or presented as large annular stimuli. In two separate experiments we measured ERPs on amblyopic patients and control subjects using face images. Latency and amplitude of averaged ERPs and their single-trial distributions were analyzed. Results. When the fovea was stimulated, latency and amplitude of the early averaged ERP components increased and were reduced, respectively, in the amblyopic compared with the fellow eye. Importantly, perifoveal stimulation also elicited similar amblyopic deficits, which were clearly significant in the case of using cortical magnification scaled stimuli. However, single-trial peak analysis revealed that foveal and perifoveal effects differed in nature: Peak amplitudes were reduced only in foveal stimulation, while latencies were delayed and jittered at both the fovea and perifovea. Event-related potentials obtained from fellow eyes were not significantly different from those of normal observers. Conclusions. Our findings revealed the existence of amblyopic deficits at the perifovea when the stimulated cortical area was matched in size to that of foveal stimulation. These deficits manifested themselves only in the temporal structure of the responses, unlike foveal deficits, which affected both component amplitude and latency

Electrophysiological Correlates of Learning-Induced Modulation of Visual Motion Processing in Humans

Training on a visual task leads to increased perceptual and neural responses to visual features that were attended during training as well as decreased responses to neglected distractor features. However, the time course of these attention-based modulations of neural sensitivity for visual features has not been investigated before. Here we measured event related potentials (ERP) in response to motion stimuli with different coherence levels before and after training on a speed discrimination task requiring object-based attentional selection of one of the two competing motion stimuli. We found that two peaks on the ERP waveform were modulated by the strength of the coherent motion signal; the response amplitude associated with motion directions that were neglected during training was smaller than the response amplitude associated with motion directions that were attended during training. The first peak of motion coherence-dependent modulation of the ERP responses was at 300 ms after stimulus onset and it was most pronounced over the occipitotemporal cortex. The second peak was around 500 ms and was focused over the parietal cortex. A control experiment suggests that the earlier motion coherence-related response modulation reflects the extraction of the coherent motion signal whereas the later peak might index accumulation and readout of motion signals by parietal decision mechanisms. These findings suggest that attention-based learning affects neural responses both at the sensory and decision processing stages

Internetfüggőség, alvászavar, depresszió, kiégés és életminőség vizsgálata középiskolai tanárok körében: összefüggést elemző modell = Internet addiction, sleep disturbance, depression, burnout and quality of life among high-school teachers: a path-analytical model

Az internet széleskörű hozzáférhetősége magávalhozta a problémás internethasználat kialakulását is (ún. internetfüggőség), amely főként a serdülőket érintő je -lenség. Felnőttek esetében viszonylag kevés adat áll ren-delkezésre. Keresztmetszeti prospektív vizsgálatunk céljaaz internetfüggőség előfordulásának és a vele asszociáltmentális eltérések (kiégés, depresszió, álmatlanság ésalacsonyabb életminőség) közötti összefüggés ponto-sabb feltérképezése középiskolai tanárok körében. Összesen 2500 papír alapú kérdőív került kiosztásra, ebből 1817 teljesen kitöltött kérdőív került értékelésre. Internetfüggőség 5,2%-ban (95/1817) volt észlelhető avizsgált populációban a felhasznált kérdőív alapján. Azinternetfüggőség szoros összefüggést mutatott a súlyosfokú kiégéssel (10,5 vs. 2,7%, p < 0,001), a mérsékelt(36,8 vs. 1,7%, p < 0,001) valamint súlyos fokú depresszi-óval (6,3 vs. 0,1%, p < 0,001), álmatlansággal (23,1 vs.11,4%, p < 0,001) és súlyos alvászavarral (27,4 vs. 3,8%,p < 0,001) továbbá a rosszabb életminőséggel (p <0,001). Az összefüggések pontosabb feltérképezése cél-jából maximális valószínűség strukturális egyenletmodellt használtunk, a közvetett hatások felmérésérebootstrapping analízist végeztünk. Eredményeink alapján oki tényezőként az internetfüg-gőség szoros összefüggést mutat a fent említett mentálistényezőkkel. Vizsgálatunk az első hazai tanulmány, amely feltárja a pontos összefüggését az internetfüggő-ség és a fent említett mentális problémák közötti össze-függést, mely felhívja a figyelmet a téma fontosságára

How the Visual Cortex Handles Stimulus Noise: Insights from Amblyopia

<div><p>Adding noise to a visual image makes object recognition more effortful and has a widespread effect on human electrophysiological responses. However, visual cortical processes directly involved in handling the stimulus noise have yet to be identified and dissociated from the modulation of the neural responses due to the deteriorated structural information and increased stimulus uncertainty in the case of noisy images. Here we show that the impairment of face gender categorization performance in the case of noisy images in amblyopic patients correlates with amblyopic deficits measured in the noise-induced modulation of the P1/P2 components of single-trial event-related potentials (ERP). On the other hand, the N170 ERP component is similarly affected by the presence of noise in the two eyes and its modulation does not predict the behavioral deficit. These results have revealed that the efficient processing of noisy images depends on the engagement of additional processing resources both at the early, feature-specific as well as later, object-level stages of visual cortical processing reflected in the P1 and P2 ERP components, respectively. Our findings also suggest that noise-induced modulation of the N170 component might reflect diminished face-selective neuronal responses to face images with deteriorated structural information.</p></div

Stimuli, experimental protocol and behavioral results.

<p>(A) Experimental protocol, which shows the general stimulus sequence (two trials). (B) Exemplar gender pair for the phase-coherent and the 50% phase noise stimulus condition. The subjects of the photographs have given written informed consent, as outlined in the PLOS consent form, to publication of their photograph. (C) Phase noise impaired accuracy in both eyes, but the impairment was significantly greater in the amblyopic eye. FE: fellow eye, AE: amblyopic eye. Error bars indicate ±SEM (N = 18, ** <i>p</i><0.01, *** <i>p</i><0.001).</p

Clinical details of amblyopic subjects.

<p>A: anisometropic, S: strabismic, SA: strabismic & anisometropic, RE: right eye, LE: left eye, VA: visual acuity, D: distant, N: near, ET: esotropia, XT: exotropia. Patients listed as strabismics and having no squint angle, have been operated on after developing amblyopia.</p

Noise effect on behavior and amplitude medians.

<p>(A) Spearman correlation between the noise-induced increase in P1 and P2 amplitude medians over the right and left hemisphere, respectively and the noise-induced decrease in performance of the amblyopic eye. Negative correlation indicates that the larger the P1/P2 amplitude increase in a subject, the smaller the performance decrement. (B) Same correlation as in panel A for amplitude median decrease of the N170 component. AE: amblyopic eye, PC: phase-coherent, N: noisy.</p