Fast Periodic Stimulation Research Articles

The Relationship Between the Benton Face Recognition Test and Electrophysiological Unfamiliar Face Individuation Response as Revealed by Fast Periodic Stimulation.

A recent approach to implicitly study face recognition skills has been the fast periodic visual stimulation (FPVS) coupled with electroencephalography (EEG). Its relationship with explicit behavioral measures of face individuation remains largely undocumented. We evaluated the relationship of the FPVS–EEG measure of individuation and performance at a computer version of the Benton Face Recognition Test. High-density EEG was recorded in 32 participants presented with an unfamiliar face at a rate of 6 Hz (F) for 60 s. Every five faces, new identities were inserted. The resulting 1.2 Hz (F/5) EEG response and its harmonics objectively indexed rapid individuation of unfamiliar faces. The robust individuation response, observed over occipitotemporal sites, was significantly correlated with speed, but not accuracy rate of the computer version of the Benton Face Recognition Test. This effect was driven by a few individuals who were particularly slow at the behavioral test and also showed the lowest face individuation response. These results highlight the importance of considering the time taken to recognize a face, as a complementary to accuracy rate variable, providing valuable information about one’s recognition skills. Overall, these observations strengthen the diagnostic value of FPVS–EEG as an objective and rapid flag for specific difficulties at individual face recognition in the human population.

Measuring face-name integration with fast periodic visual stimulation

Associating specific names to faces of familiar identity is crucial for social interactions. This is a difficult process, which can be severely disrupted in neurodegenerative disorders such as Alzheimer's disease or temporal epilepsy. An outstanding issue is whether face and name representations are kept separated in the human brain and associated through re-entrant interactions, or if they are integrated into common representation at higher stages. Here we addressed this issue with fast periodic stimulation in EEG. Healthy subjects (n=12) were exposed to randomly alternating face photographs and written names of a famous identity (base stimuli) at a fast rate (3.999 Hz, about 4 images per second) while recording their brain activity with high density (128 channels) scalp EEG. A change in identity (either presented as a face or a name) occurred every seven stimuli (i.e., 0.5713 Hz; oddball stimuli). Following a few minutes of recordings, there were significant electrophysiological responses at the frequency of a face identity change (i.e., 0.5713 and harmonics), suggesting integrated representations of faces and names. Experiment 2 (n=20) replicated these findings and added two control conditions: A face only condition in which the specific identity names presented at the base rate were replaced by other famous names, and a name only condition which followed the same principle for names. There were much weaker amplitudes at the periodic change of identity in control conditions. Most importantly, the sum of the two control conditions' activation was weaker than the effect found in the main condition, in particular over the left medial occipital region and extending to the posterior part of the left occipito-temporal region. Overall, these observations provide evidence for integrated face/name representations in the human brain, with a left occipito-temporal locus.

Fast periodic stimulation (FPS): a highly effective approach in fMRI brain mapping.

Defining the neural basis of perceptual categorization in a rapidly changing natural environment with low-temporal resolution methods such as functional magnetic resonance imaging (fMRI) is challenging. Here, we present a novel fast periodic stimulation (FPS)-fMRI approach to define face-selective brain regions with natural images. Human observers are presented with a dynamic stream of widely variable natural object images alternating at a fast rate (6images/s). Every 9s, a short burst of variable face images contrasting with object images in pairs induces an objective face-selective neural response at 0.111Hz. A model-free Fourier analysis achieves a twofold increase in signal-to-noise ratio compared to a conventional block-design approach with identical stimuli and scanning duration, allowing to derive a comprehensive map of face-selective areas in the ventral occipito-temporal cortex, including the anterior temporal lobe (ATL), in all individual brains. Critically, periodicity of the desired category contrast and random variability among widely diverse images effectively eliminates the contribution of low-level visual cues, and lead to the highest values (80-90%) of test-retest reliability in the spatial activation map yet reported in imaging higher level visual functions. FPS-fMRI opens a new avenue for understanding brain function with low-temporal resolution methods.

The development of category specificity in infancy – What can we learn from electrophysiology?

In this review I address the question why relatively little is currently known about the neural bases of category learning and beginning category identification in infancy. Electrophysiological research on infants' basic-level and global-level categorization has mainly focused on general measures of visual attention, not on specific neural processes underlying the development and identification of visual categories. Our knowledge on categorization processes in the infant brain is mainly limited to faces as categories. I will call for the use of EEG-based techniques such as rapid repetition ERP paradigms and fast periodic stimulation that have only rarely been used with infants in order to gain a better understanding of the development of category representations in the infant brain.

The effect of fast periodic stimulation on the face-selective patches of the monkey superior temporal sulcus: An fMRI adaptation study

The effect of fast periodic stimulation on the face-selective patches of the monkey superior temporal sulcus: An fMRI adaptation study

Understanding high-level visual discrimination by means of fast periodic oddball stimulation

Event Abstract Back to Event Understanding high-level visual discrimination by means of fast periodic oddball stimulation Joan Liu-Shuang1*, Anthony Norcia2 and Bruno Rossion1 1 University of Louvain, Belgium 2 Stanford University, United States The perceptual mechanisms underlying human observers’ ability to discriminate complex visual objects remain unresolved. This is especially true for faces, which human observers can efficiently individualise despite their high similarity. Previous studies have used classic adaptation paradigms to investigate the sensitivity of the visual system to face identity (i.e., 1; 2). In contrast to this approach, which measures sensitivity by comparing levels of adaptation between conditions containing same and different faces, here we propose a novel paradigm using fast periodic oddball stimulation that quantifies the discrimination response as an independent unit. We recorded 128-channel EEG in 20 observers presented with 60-second sequences of face stimuli shown at a constant frequency of 5.88 Hz. A “base face” (A) was repeated throughout each sequence with face size randomly varying at every cycle. Different faces (B, C, D…) were introduced at fixed intervals (every 4 stimuli, or 5.88 Hz/5 = 1.18 Hz), resulting in the following sequence structure: AAAABAAAAC... The presence of a response at 1.18 Hz is taken as an index of face discrimination, independently of the response at the main stimulation frequency of 5.88 Hz. To ensure that signal at 1.18 Hz truly reflected high-level face processing, we manipulated orientation (upright vs. inverted, Experiment 1) and contrast (normal contrast vs. contrast-reversed, Experiment 2). Both experiments showed significant increases of EEG amplitude at 1.18 Hz and its harmonics (2F = 2.35 Hz, 3F = 3.53 Hz…), with peak values in the right occipito-temporal channels. While the basic 5.88 Hz response was large for inverted and contrast-reversed faces, responses at 1.18 Hz and its harmonics – corresponding to face discrimination – were minimal in these conditions. Given these findings, the signal at the specific frequency of identity-change can be interpreted as an objective measure of face individualisation. In line with a recent study (3) highlighting the efficiency of periodic visual stimulation in investigating high-level visual processing, the current results underline the interest of the fast periodic oddball paradigm to explore fine-grained visual discrimination. References (1) Grill-Spector, K., & Malach, R. (2001). fMR-adaptation: a tool for studying the functional properties of human cortical neurons. Acta Psychologica, 107, 293–321. (2) Jacques, C., d’Arripe, O., & Rossion, B. (2007). The time course of the inversion effect during individual face discrimination. Journal of Vision, 7, 1–9. (3) Rossion, B., & Boremanse, A. (2011). Robust sensitivity to facial identity in the right human occipito-temporal cortex as revealed by steady-state visual-evoked potentials. Journal of Vision, 11, 1–21. Keywords: face processing, fast periodic stimulation, steady state visually evoked potentials (ssVEP), visual discrimination, EEG Conference: Belgian Brain Council, Liège, Belgium, 27 Oct - 27 Oct, 2012. Presentation Type: Poster Presentation Topic: Other basic/clinical neurosciences topic Citation: Liu-Shuang J, Norcia A and Rossion B (2012). Understanding high-level visual discrimination by means of fast periodic oddball stimulation. Conference Abstract: Belgian Brain Council. doi: 10.3389/conf.fnhum.2012.210.00005 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 07 Sep 2012; Published Online: 12 Sep 2012. * Correspondence: Ms. Joan Liu-Shuang, University of Louvain, Louvain-la-Neuve, Belgium, joan.liu@uclouvain.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joan Liu-Shuang Anthony Norcia Bruno Rossion Google Joan Liu-Shuang Anthony Norcia Bruno Rossion Google Scholar Joan Liu-Shuang Anthony Norcia Bruno Rossion PubMed Joan Liu-Shuang Anthony Norcia Bruno Rossion Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Improving evoked response audiometry

Normative studies were carried out with 8 adult subjects whose averaged evoked responses to auditory stimuli were scored visually and by a number of differently defined quantitative methods (machine scoring). In order to compare different scoring methods a common signal-to-noise ratio measure was introduced based on a model where noise is distributed normally and signal is additive. Visual and machine scoring proved to be approximately equally sensitive, but the latter lends itself to a superior testing procedure which takes only one-third as long for equivalent results and is not contaminated by subjective error. The authors believe that the greatest promise for improving evoked response audiometry lies in the exploration of the new techniques proposed earlier. Progress in proving out one of these techniques, fast periodic stimulation, is reported.

Improving evoked response audiometry with special reference to the use of machine scoring.

The use of visual scoring of evoked response (ER) records to detect auditory threshold is reviewed, and it is concluded that current ER audiometry is not a reliable clinical tool because of substantial error compounded by subjectivity of score.The mathematics underlying ER detection is reviewed. The critical part played by the signal-to-noise ratio (f) and techniques for enhancing f are discussed. The accepted techniques of averaging, segregation by EEG classification before averaging, and filtering are considered, along with two newly proposed techiques, fast periodic stimulation and correction of records by predictors averaging. These hold promise of enhancing the effective f by a factor of about 3 and reducing the lenght of test runs by an order of magnitude.Self-normalization is introduced in order to define scores which are sensitive primarily to f rather than to these scores is relatively invariant from subject to subject since it depends on f alone. This simplifies normative studies, particularly for the no-ER condition for which f = 0, since estimates of type-II error, false positives, are independent of the subject.Five machine scores are defined: (1) normalized peak-to-trough amplitudes; (2) Normalized rectified mean amplitudes; (3) the ratio of power of the ER to that of the background EEG; (4) the correlation coefficients between subsets in the same run; and (5) a combined measure based on (3) and (4). The sensitivity of each of these measures and their dependence on f are considered.From the explorations thus far, it is concluded that machine scoring techiques are available which are at least as sensitive and reliable as visual scoring and which can be implemented by relatively simple, inexpensive special purpose computers. Furthermore, since machine scoring lends itself to a superior test strategy, it is concluded that machine scoring can greatly increase the sensitivity and reliability of ER audiometry. These conclusions apply without taking into account the vast improvements possible if the newly proposed techniques (fast periodic stimulation and correction by prediction) for enhancing f should prove successful.