scholarly journals Different Neural Mechanisms within Occipitotemporal Cortex Underlie Repetition Suppression across Same and Different-Size Faces

2012 ◽  
Vol 23 (5) ◽  
pp. 1073-1084 ◽  
Author(s):  
Michael. P. Ewbank ◽  
Richard N. Henson ◽  
James B. Rowe ◽  
Raliza S. Stoyanova ◽  
Andrew J. Calder
Keyword(s):  
Neural Mechanisms ◽  
Repetition Suppression ◽  
Occipitotemporal Cortex

Functionally Separable Font-invariant and Font-sensitive Neural Populations in Occipitotemporal Cortex

2019 ◽  
Vol 31 (7) ◽  
pp. 1018-1029 ◽  
Author(s):  
Zhiheng Zhou ◽  
Tutis Vilis ◽  
Lars Strother
Keyword(s):  
Visual Word ◽  
Neural Mechanisms ◽  
Word Form ◽  
Invariant Representation ◽  
Visual Word Form Area ◽  
Repetition Suppression ◽  
Neural Populations ◽  
Occipitotemporal Cortex ◽  
Middle Occipital Gyrus ◽  
Repeated Words

Reading relies on the rapid visual recognition of words viewed in a wide variety of fonts. We used fMRI to identify neural populations showing reduced fMRI responses to repeated words displayed in different fonts (“font-invariant” repetition suppression). We also identified neural populations showing greater fMRI responses to words repeated in a changing font as compared with words repeated in the same font (“font-sensitive” release from repetition suppression). We observed font-invariant repetition suppression in two anatomically distinct regions of the left occipitotemporal cortex (OT), a “visual word form area” in mid-fusiform cortex, and a more posterior region in the middle occipital gyrus. In contrast, bilateral shape-selective lateral occipital cortex and posterior fusiform showed considerable sensitivity to font changes during the viewing of repeated words. Although the visual word form area and the left middle occipital gyrus showed some evidence of font sensitivity, both regions showed a relatively greater degree of font invariance than font sensitivity. Our results show that the neural mechanisms in the left OT involved in font-invariant word recognition are anatomically distinct from those sensitive to font-related shape changes. We conclude that font-invariant representation of visual word form is instantiated at multiple levels by anatomically distinct neural mechanisms within the left OT.

Repetition Suppression of Induced Gamma Activity Predicts Enhanced Orienting toward a Novel Stimulus in 6-month-old Infants

2008 ◽  
Vol 20 (12) ◽  
pp. 2137-2152 ◽  
Author(s):  
Kelly A. Snyder ◽  
Andreas Keil
Keyword(s):  
Visual Processing ◽  
Novelty Detection ◽  
Neural Mechanisms ◽  
Human Infant ◽  
Gamma Activity ◽  
Repeated Stimulus ◽  
Repetition Suppression ◽  
The Face ◽  
Over 40 Years

Habituation refers to a decline in orienting or responding to a repeated stimulus, and can be inferred to reflect learning about the properties of the repeated stimulus when followed by increased orienting to a novel stimulus (i.e., novelty detection). Habituation and novelty detection paradigms have been used for over 40 years to study perceptual and mnemonic processes in the human infant, yet important questions remain about the nature of these processes in infants. The aim of the present study was to examine the neural mechanisms underlying habituation and novelty detection in infants. Specifically, we investigated changes in induced alpha, beta, and gamma activity in 6-month-old infants during repeated presentations of either a face or an object, and examined whether these changes predicted behavioral responses to novelty at test. We found that induced gamma activity over occipital scalp regions decreased with stimulus repetition in the face condition but not in the toy condition, and that greater decreases in the gamma band were associated with enhanced orienting to a novel face at test. The pattern and topography of these findings are consistent with observations of repetition suppression in the occipital–temporal visual processing pathway, and suggest that encoding in infant habituation paradigms may reflect a form of perceptual learning. Implications for the role of repetition suppression in infant habituation and novelty detection are discussed with respect to a biased competition model of visual attention.

scholarly journals Repetition Probability Effects for Words Depend on Language Knowledge

2021 ◽  
Author(s):  
Chenglin Li ◽  
Gyula Kovacs
Keyword(s):  
Word Processing ◽  
Mother Tongue ◽  
Visual Word ◽  
Neural Mechanisms ◽  
Chinese Characters ◽  
Visual Word Form Area ◽  
Repetition Suppression ◽  
Language Knowledge ◽  
Prior Experiences ◽  
Predictive Processes

The magnitude of repetition suppression (RS), measured by fMRI, is modulated by the probability of repetitions (P(rep)) for various sensory stimulus categories. It has been suggested that for visually presented simple letters this P(rep) effect depends on the prior practices of the participants with the stimuli. Here we tested further if previous experiences affect the neural mechanisms of RS, leading to the modulatory effects of stimulus P(rep), for more complex lexical stimuli as well. We measured the BOLD signal in the Visual Word Form Area (VWFA) of native Chinese and German participants and estimated the P(rep) effects for Chinese characters and German words. The results showed a significant P(rep) effect for stimuli of the mother tongue in both participant groups. Interestingly, Chinese participants, learning German as a second language, also showed a significant P(rep) modulation of RS for German words while the German participants who had no prior experiences with the Chinese characters showed no such effects. Our findings suggest that P(rep) effects on RS are manifest for visual word processing as well, but only for words of a language with which the participants have prior experiences. These results support further the idea that predictive processes, estimated by P(rep) modulations of RS, require prior experiences.

scholarly journals Orthographic Priming in Braille Reading as Evidence for Task-specific Reorganization in the Ventral Visual Cortex of the Congenitally Blind

2019 ◽  
Vol 31 (7) ◽  
pp. 1065-1078
Author(s):  
Katarzyna Rączy ◽  
Aleksandra Urbańczyk ◽  
Maksymilian Korczyk ◽  
Jakub Michał Szewczyk ◽  
Ewa Sumera ◽  
...  
Keyword(s):  
Orthographic Processing ◽  
Sentence Structure ◽  
Input Modality ◽  
Double Dissociation ◽  
Repetition Suppression ◽  
Congenitally Blind ◽  
Auditory Priming ◽  
Occipitotemporal Cortex ◽  
Orthographic Priming ◽  
Language Areas

The task-specific principle asserts that, following deafness or blindness, the deprived cortex is reorganized in a manner such that the task of a given area is preserved even though its input modality has been switched. Accordingly, tactile reading engages the ventral occipitotemporal cortex (vOT) in the blind in a similar way to regular reading in the sighted. Others, however, show that the vOT of the blind processes spoken sentence structure, which suggests that the task-specific principle might not apply to vOT. The strongest evidence for the vOT's engagement in sighted reading comes from orthographic repetition–suppression studies. Here, congenitally blind adults were tested in an fMRI repetition–suppression paradigm. Results reveal a double dissociation, with tactile orthographic priming in the vOT and auditory priming in general language areas. Reconciling our finding with other evidence, we propose that the vOT in the blind serves multiple functions, one of which, orthographic processing, overlaps with its function in the sighted.

Do social hierarchies modulate neural mechanisms of repetition suppression?

2013 ◽  
Author(s):  
Alba Ayneto ◽  
Hernando Santamaria Garcia ◽  
Nuria Sebastian-Galles
Keyword(s):  
Neural Mechanisms ◽  
Social Hierarchies ◽  
Repetition Suppression

scholarly journals Dissociable Forms of Repetition Priming: A Computational Model

2014 ◽  
Vol 26 (4) ◽  
pp. 712-738 ◽  
Author(s):  
Kirill Makukhin ◽  
Scott Bolland
Keyword(s):  
Computational Model ◽  
Neural Activity ◽  
Repetition Priming ◽  
Hebbian Learning ◽  
Neural Mechanisms ◽  
Stimulus Repetition ◽  
Repetition Suppression ◽  
Opposite Trend ◽  
Proposed Model ◽  
The Brain

Nondeclarative memory and novelty processing in the brain is an actively studied field of neuroscience, and reducing neural activity with repetition of a stimulus (repetition suppression) is a commonly observed phenomenon. Recent findings of an opposite trend—specifically, rising activity for unfamiliar stimuli—question the generality of repetition suppression and stir debate over the underlying neural mechanisms. This letter introduces a theory and computational model that extend existing theories and suggests that both trends are, in principle, the rising and falling parts of an inverted U-shaped dependence of activity with respect to stimulus novelty that may naturally emerge in a neural network with Hebbian learning and lateral inhibition. We further demonstrate that the proposed model is sufficient for the simulation of dissociable forms of repetition priming using real-world stimuli. The results of our simulation also suggest that the novelty of stimuli used in neuroscientific research must be assessed in a particularly cautious way. The potential importance of the inverted-U in stimulus processing and its relationship to the acquisition of knowledge and competencies in humans is also discussed.

scholarly journals From neurons to voxels - repetition suppression is best modelled by local neural scaling

2017 ◽  
Author(s):  
Arjen Alink ◽  
Hunar Abdulrahman ◽  
Richard N. Henson
Keyword(s):  
Computational Models ◽  
Neural Mechanisms ◽  
Functional Magnetic Resonance ◽  
Repetition Effects ◽  
Local Scaling ◽  
Tuning Curves ◽  
Repetition Suppression ◽  
The Difference ◽  
Fmri Adaptation ◽  
Parameter Values

Inferring neural mechanisms from functional magnetic resonance imaging (fMRI) is challenging because the fMRI signal integrates over millions of neurons. One approach is to compare computational models that map neural activity to fMRI responses, to see which best predicts fMRI data. We used this approach to compare four possible neural mechanisms of fMRI adaptation to repeated stimuli (scaling, sharpening, repulsive shifting and attractive shifting), acting across three domains (global, local and remote). Six features of fMRI repetition effects were identified, both univariate and multivariate, from two independent fMRI experiments. After searching over parameter values, only the local scaling model could simultaneously fit all data features from both experiments. Thus fMRI stimulus repetition effects are best captured by down-scaling neuronal tuning curves in proportion to the difference between the stimulus and neuronal preference. These results emphasize the importance of formal modelling for bridging neuronal and fMRI levels of investigation.

scholarly journals Forward models demonstrate that repetition suppression is best modelled by local neural scaling

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Arjen Alink ◽  
Hunar Abdulrahman ◽  
Richard N. Henson
Keyword(s):  
Computational Models ◽  
Neural Mechanisms ◽  
Functional Magnetic Resonance ◽  
Repetition Effects ◽  
Local Scaling ◽  
Tuning Curves ◽  
Repetition Suppression ◽  
The Difference ◽  
Fmri Adaptation ◽  
Parameter Values

Abstract Inferring neural mechanisms from functional magnetic resonance imaging (fMRI) is challenging because the fMRI signal integrates over millions of neurons. One approach is to compare computational models that map neural activity to fMRI responses, to see which best predicts fMRI data. We use this approach to compare four possible neural mechanisms of fMRI adaptation to repeated stimuli (scaling, sharpening, repulsive shifting and attractive shifting), acting across three domains (global, local and remote). Six features of fMRI repetition effects are identified, both univariate and multivariate, from two independent fMRI experiments. After searching over parameter values, only the local scaling model can simultaneously fit all data features from both experiments. Thus fMRI stimulus repetition effects are best captured by down-scaling neuronal tuning curves in proportion to the difference between the stimulus and neuronal preference. These results emphasise the importance of formal modelling for bridging neuronal and fMRI levels of investigation.

Two Kinds of fMRI Repetition Suppression? Evidence for Dissociable Neural Mechanisms

2008 ◽  
Vol 99 (6) ◽  
pp. 2877-2886 ◽  
Author(s):  
Russell A. Epstein ◽  
Whitney E. Parker ◽  
Alana M. Feiler
Keyword(s):  
Short Interval ◽  
Brain Regions ◽  
Neural Mechanisms ◽  
Functional Magnetic Resonance ◽  
Resonance Imaging ◽  
Repetition Suppression ◽  
Underlying Mechanisms ◽  
Cortical Regions ◽  
Formal Requirements ◽  
Parahippocampal Place Area

Repetition suppression (RS) is a reduction of neural response that is often observed when stimuli are presented more than once. Many functional magnetic resonance imaging (fMRI) studies have exploited RS to probe the sensitivity of cortical regions to variations in different stimulus dimensions; however, the neural mechanisms underlying fMRI-RS are not fully understood. Here we test the hypothesis that long-interval (between-trial) and short-interval (within-trial) RS effects are caused by distinct and independent neural mechanisms. Subjects were scanned while viewing visual scenes that were repeated over both long and short intervals. Within the parahippocampal place area (PPA) and other brain regions, suppression effects relating to both long- and short-interval repetition were observed. Critically, two sources of evidence indicated that these effects were engendered by different underlying mechanisms. First, long- and short-interval RS effects were entirely noninteractive even although they were measured within the same set of trials during which subjects performed a constant behavioral task, thus fulfilling the formal requirements for a process dissociation. Second, long- and short-interval RS were differentially sensitive to viewpoint: short-interval RS was only significant when scenes were repeated from the same viewpoint while long-interval RS less viewpoint-dependent. Taken together, these results indicate that long- and short-interval fMRI-RS are mediated by different neural mechanisms that independently modulate the overall fMRI signal. These findings have important implications for understanding the results of studies that use fMRI-RS to explore representational spaces.

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