scholarly journals Retinotopic and Lateralized Processing of Spatial Frequencies in Human Visual Cortex during Scene Categorization

2013 ◽  
Vol 25 (8) ◽  
pp. 1315-1331 ◽  
Author(s):  
Benoit Musel ◽  
Cécile Bordier ◽  
Michel Dojat ◽  
Cédric Pichat ◽  
Sylvie Chokron ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Anterior Part ◽  
Hemispheric Specialization ◽  
Temporal Cortex ◽  
Posterior Part ◽  
Occipital Cortex ◽  
Natural Scenes ◽  
Group Level ◽  
Scene Categorization ◽  
Spatial Frequencies

Using large natural scenes filtered in spatial frequencies, we aimed to demonstrate that spatial frequency processing could not only be retinotopically mapped but could also be lateralized in both hemispheres. For this purpose, participants performed a categorization task using large black and white photographs of natural scenes (indoors vs. outdoors, with a visual angle of 24° × 18°) filtered in low spatial frequencies (LSF), high spatial frequencies (HSF), and nonfiltered scenes, in block-designed fMRI recording sessions. At the group level, the comparison between the spatial frequency content of scenes revealed first that, compared with HSF, LSF scene categorization elicited activation in the anterior half of the calcarine fissures linked to the peripheral visual field, whereas, compared with LSF, HSF scene categorization elicited activation in the posterior part of the occipital lobes, which are linked to the fovea, according to the retinotopic property of visual areas. At the individual level, functional activations projected on retinotopic maps revealed that LSF processing was mapped in the anterior part of V1, whereas HSF processing was mapped in the posterior and ventral part of V2, V3, and V4. Moreover, at the group level, direct interhemispheric comparisons performed on the same fMRI data highlighted a right-sided occipito-temporal predominance for LSF processing and a left-sided temporal cortex predominance for HSF processing, in accordance with hemispheric specialization theories. By using suitable method of analysis on the same data, our results enabled us to demonstrate for the first time that spatial frequencies processing is mapped retinotopically and lateralized in human occipital cortex.

scholarly journals Residual abilities in age-related macular degeneration to process spatial frequencies during natural scene categorization

2011 ◽  
Vol 28 (6) ◽  
pp. 529-541 ◽  
Author(s):  
BENOIT MUSEL ◽  
RUXANDRA HERA ◽  
SYLVIE CHOKRON ◽  
DAVID ALLEYSSON ◽  
CHRISTOPHE CHIQUET ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Macular Degeneration ◽  
Reaction Times ◽  
Age Related Macular Degeneration ◽  
Natural Scenes ◽  
Natural Scene ◽  
Scene Categorization ◽  
Age Related ◽  
Spatial Frequencies ◽  
Healthy Participants

AbstractAge-related macular degeneration (AMD) is characterized by a central vision loss. We explored the relationship between the retinal lesions in AMD patients and the processing of spatial frequencies in natural scene categorization. Since the lesion on the retina is central, we expected preservation of low spatial frequency (LSF) processing and the impairment of high spatial frequency (HSF) processing. We conducted two experiments that differed in the set of scene stimuli used and their exposure duration. Twelve AMD patients and 12 healthy age-matched participants in Experiment 1 and 10 different AMD patients and 10 healthy age-matched participants in Experiment 2 performed categorization tasks of natural scenes (Indoors vs. Outdoors) filtered in LSF and HSF. Experiment 1 revealed that AMD patients made more no-responses to categorize HSF than LSF scenes, irrespective of the scene category. In addition, AMD patients had longer reaction times to categorize HSF than LSF scenes only for indoors. Healthy participants’ performance was not differentially affected by spatial frequency content of the scenes. In Experiment 2, AMD patients demonstrated the same pattern of errors as in Experiment 1. Furthermore, AMD patients had longer reaction times to categorize HSF than LSF scenes, irrespective of the scene category. Again, spatial frequency processing was equivalent for healthy participants. The present findings point to a specific deficit in the processing of HSF information contained in photographs of natural scenes in AMD patients. The processing of LSF information is relatively preserved. Moreover, the fact that the deficit is more important when categorizing HSF indoors, may lead to new perspectives for rehabilitation procedures in AMD.

Natural scenes have matched amplitude-modulated sounds that systematically influence visual scanning

2012 ◽  
Vol 25 (0) ◽  
pp. 121
Author(s):  
Marcia Grabowecky ◽  
Aleksandra Sherman ◽  
Satoru Suzuki
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Memory Task ◽  
High Spatial Frequency ◽  
Visual Object ◽  
Natural Scenes ◽  
Scale Invariant ◽  
Visual Coding ◽  
Visual Spatial ◽  
Spatial Frequencies

We have previously demonstrated a linear perceptual relationship between auditory amplitude-modulation (AM) rate and visual spatial-frequency using gabors as the visual stimuli. Can this frequency-based auditory–visual association influence perception of natural scenes? Participants consistently matched specific auditory AM rates to diverse visual scenes (nature, urban, and indoor). A correlation analysis indicated that higher subjective density ratings were associated with faster AM-rate matches. Furthermore, both the density ratings and AM-rate matches were relatively scale invariant, suggesting that the underlying crossmodal association is between visual coding of object-based density and auditory coding of AM rate. Based on these results, we hypothesized that concurrently presented fast (7 Hz) or slow (2 Hz) AM-rates might influence how visual attention is allocated to dense or sparse regions within a scene. We tested this hypothesis by monitoring eye movements while participants examined scenes for a subsequent memory task. To determine whether fast or slow sounds guided eye movements to specific spatial frequencies, we computed the maximum contrast energy at each fixation across 12 spatial frequency bands ranging from 0.06–10.16 cycles/degree. We found that the fast sound significantly guided eye movements toward regions of high spatial frequency, whereas the slow sound guided eye movements away from regions of high spatial frequency. This suggests that faster sounds may promote a local scene scanning strategy, acting as a ‘filter’ to individuate objects within dense regions. Our results suggest that auditory AM rate and visual object density are crossmodally associated, and that this association can modulate visual inspection of scenes.

Spatio-Chromatic Information Content of Natural Scenes

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 162-162 ◽  
Author(s):  
T Troscianko ◽  
C A Parraga ◽  
G Brelstaff ◽  
D Carr ◽  
K Nelson
Keyword(s):  
Spatial Frequency ◽  
Human Vision ◽  
Natural Scenes ◽  
Data Set ◽  
Frequency Space ◽  
Sensitivity Functions ◽  
Visual Encoding ◽  
Spatial Frequencies ◽  
Hyper Spectral ◽  
Fourier Spectra

A common assumption in the study of the relationship between human vision and the visual environment is that human vision has developed in order to encode the incident information in an optimal manner. Such arguments have been used to support the 1/f dependence of scene content as a function of spatial frequency. In keeping with this assumption, we ask whether there are any important differences between the luminance and (r/g) chrominance Fourier spectra of natural scenes, the simple expectation being that the chrominance spectrum should be relatively richer in low spatial frequencies than the luminance spectrum, to correspond with the different shape of luminance and chrominance contrast sensitivity functions. We analysed a data set of 29 images of natural scenes (predominantly of vegetation at different distances) which were obtained with a hyper-spectral camera (measuring the scene through a set of 31 wavelength bands in the range 400 – 700 nm). The images were transformed to the three Smith — Pokorny cone fundamentals, and further transformed into ‘luminance’ (r+g) and ‘chrominance’ (r-g) images, with various assumptions being made about the relative weighting of the r and g components, and the form of the chrominance response. We then analysed the Fourier spectra of these images using logarithmic intervals in spatial frequency space. This allowed a determination of the total energy within each Fourier band for each of the luminance and chrominance representations. The results strongly indicate that, for the set of scenes studied here, there was no evidence of a predominance of low-spatial-frequency chrominance information. Two classes of explanation are possible: (a) that raw Fourier content may not be the main organising principle determining visual encoding of colour, and/or (b) that our scenes were atypical of what may have driven visual evolution. We present arguments in favour of both of these propositions.

Hemispheric specialization for spatial frequency processing in the analysis of natural scenes

2003 ◽  
Vol 53 (2) ◽  
pp. 278-282 ◽  
Author(s):  
Carole Peyrin ◽  
Alan Chauvin ◽  
Sylvie Chokron ◽  
Christian Marendaz
Keyword(s):  
Spatial Frequency ◽  
Hemispheric Specialization ◽  
Natural Scenes ◽  
Frequency Processing

scholarly journals Scene Categorization in Alzheimer's Disease: A Saccadic Choice Task

2015 ◽  
Vol 5 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Quentin Lenoble ◽  
Giovanna Bubbico ◽  
Sébastien Szaffarczyk ◽  
Florence Pasquier ◽  
Muriel Boucart
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Young People ◽  
Occipital Cortex ◽  
Choice Task ◽  
Natural Scenes ◽  
Saccadic Eye Movement ◽  
Scene Categorization ◽  
Global Properties ◽  
Cerebral Reorganization

Aims: We investigated the performance in scene categorization of patients with Alzheimer's disease (AD) using a saccadic choice task. Method: 24 patients with mild AD, 28 age-matched controls and 26 young people participated in the study. The participants were presented pairs of coloured photographs and were asked to make a saccadic eye movement to the picture corresponding to the target scene (natural vs. urban, indoor vs. outdoor). Results: The patients' performance did not differ from chance for natural scenes. Differences between young and older controls and patients with AD were found in accuracy but not saccadic latency. Conclusions: The results are interpreted in terms of cerebral reorganization in the prefrontal and temporo-occipital cortex of patients with AD, but also in terms of impaired processing of visual global properties of scenes.

scholarly journals Transformation from local image contrast to location-independent numerosity tuning in human extrastriate cortex

2021 ◽  
Author(s):  
Jacob M Paul ◽  
Martijn van Ackooij ◽  
Tuomas C ten Cate ◽  
Benjamin M Harvey
Keyword(s):  
Visual Cortex ◽  
Spatial Frequency ◽  
Computational Modelling ◽  
Occipital Cortex ◽  
Extrastriate Cortex ◽  
Visual Responses ◽  
Fourier Decomposition ◽  
Visual Spatial ◽  
Spatial Frequencies ◽  
Item Size

Many animals use visual numerosity, the number of items in a group, to guide behavior. Neurons in human association cortices show numerosity-tuned responses, decreasing amplitude with distance from a specific numerosity. How are such responses derived from early visual responses? Recent studies show aggregate response amplitudes in human early visual cortex monotonically increase with numerosity, regardless of object size and spacing. This is surprising because numerosity is typically considered a high-level visual or cognitive feature. Here we first use computational modelling of 7T fMRI data to show these monotonic responses originate at the stimulus's retinotopic location in primary visual cortex (V1). Given this location, we then ask whether these monotonic responses can be better described by V1's established response properties. We characterize the Fourier decomposition (into contrast at specific orientations and spatial frequencies) of laboratory numerosity stimuli. This demonstrates that aggregate Fourier power (at all orientations and spatial frequencies) nonlinearly follows numerosity with little effect of item size, spacing or shape: it is proportional to numerosity at a fixed contrast. This nonlinear relationship lets us distinguish predictions of responses to Fourier power and numerosity. Monotonic responses are better predicted by Fourier power, later tuned responses are better predicted by numerosity. Tuned responses emerge after lateral occipital cortex and are independent of retinotopic location. We propose that numerosity's straightforward perception and neural responses reflect its straightforward estimation from early visual spatial frequency domain image representations. Our numerical vision may have built on behaviorally beneficial analysis of spatial frequency in simpler animals.

Spatial-Frequency Characteristics of Different Areas of Human Cortex

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 167-167
Author(s):  
A K Harauzov ◽  
Y E Shelepin ◽  
S V Pronin
Keyword(s):  
Spatial Frequency ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Occipital Lobe ◽  
Occipital Cortex ◽  
Normal Subjects ◽  
Sine Wave ◽  
Electrode System ◽  
Frequency Characteristics ◽  
Spatial Frequencies

We recorded visual evoked potentials in normal subjects from different areas of the occipital cortex, from the temporal and parietal lobes according to the ‘ten - twenty’ electrode system. Stimuli were black-and-white sine-wave gratings with eight different spatial frequencies in the range 0.45 to 14.4 cycles deg−1, presented at four different temporal frequencies (1, 2, 4, 8 Hz). Stimulation was either contrast-reversal or onset. VEPs were analysed both by component analysis and by Fourier transformation. Spatial characteristics were measured from the dependence of the amplitudes and latencies of the main response components (N1, P1, N2, P2) on the contrast and spatial frequency of the gratings. The characteristics obtained in the occipital lobe are in accordance with earlier experimental data [Regan, 1989 Human Electrophysiology (Amsterdam: Elsevier)]. When the temporal frequency of stimulation was increased, the maximum of the spatial-frequency curves shifted to lower spatial frequencies. However, we found differences in the spatial-frequency characteristics of different cortical areas. The results are discussed in terms of differences in the spatial and temporal tuning of the receptive fields of neurons in these areas.

Fine structure of the rectal papillae of the oriental fruuit fly, Dacus dorsalis Hendel (Tephritidae, Diptera Insecta)

1990 ◽  
Vol 48 (3) ◽  
pp. 498-499
Author(s):  
Len Wen-Yung ◽  
Mei-Jung Lin
Keyword(s):  
Fine Structure ◽  
Cell Membrane ◽  
Intercellular Space ◽  
Anterior Part ◽  
Apical Cell ◽  
Posterior Part ◽  
Apical Cell Membrane ◽  
Dacus Dorsalis ◽  
Radial Cell ◽  
Circular Base

Four cone-shaped rectal papillae locate at the anterior part of the rectum in Dacus dorsalis fly. The circular base of the papilla protrudes into the haemolymph (Fig. 1,2) and the rest cone-shaped tip (Fig. 2) inserts in the rectal lumen. The base is surrounded with the cuticle (Fig. 5). The internal structure of the rectal papilla (Fig. 3) comprises of the cortex with the columnar epithelial cells and a rod-shaped medulla. Between them, there is the infundibular space and many trabeculae connect each other. Several tracheae insert into the papilla through the top of the medulla, then run into the cortical epithelium and locate in the intercellular space. The intercellular sinuses distribute in the posterior part of the rectal papilla.The cortex of the base divides into about thirty segments. Between segments there is a radial cell (Fig. 4). Under the cuticle, the apical cell membrane of the cortical epithelium is folded into a regular border of leaflets (Fig. 5).

scholarly journals The lateral intraparietal sulcus takes viewpoint changes into account during memory-guided attention in natural scenes

2021 ◽  
Vol 226 (4) ◽  
pp. 989-1006
Author(s):  
Ilenia Salsano ◽  
Valerio Santangelo ◽  
Emiliano Macaluso
Keyword(s):  
Spatial Information ◽  
Temporal Cortex ◽  
Independent Effect ◽  
Long Term Memory ◽  
Natural Scenes ◽  
Behavioral Measures ◽  
Attention Network ◽  
Low Contrast ◽  
Dorsal Attention Network

AbstractPrevious studies demonstrated that long-term memory related to object-position in natural scenes guides visuo-spatial attention during subsequent search. Memory-guided attention has been associated with the activation of memory regions (the medial-temporal cortex) and with the fronto-parietal attention network. Notably, these circuits represent external locations with different frames of reference: egocentric (i.e., eyes/head-centered) in the dorsal attention network vs. allocentric (i.e., world/scene-centered) in the medial temporal cortex. Here we used behavioral measures and fMRI to assess the contribution of egocentric and allocentric spatial information during memory-guided attention. At encoding, participants were presented with real-world scenes and asked to search for and memorize the location of a high-contrast target superimposed in half of the scenes. At retrieval, participants viewed again the same scenes, now all including a low-contrast target. In scenes that included the target at encoding, the target was presented at the same scene-location. Critically, scenes were now shown either from the same or different viewpoint compared with encoding. This resulted in a memory-by-view design (target seen/unseen x same/different view), which allowed us teasing apart the role of allocentric vs. egocentric signals during memory-guided attention. Retrieval-related results showed greater search-accuracy for seen than unseen targets, both in the same and different views, indicating that memory contributes to visual search notwithstanding perspective changes. This view-change independent effect was associated with the activation of the left lateral intra-parietal sulcus. Our results demonstrate that this parietal region mediates memory-guided attention by taking into account allocentric/scene-centered information about the objects' position in the external world.

scholarly journals Flexible time course of spatial frequency use during scene categorization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sandro L. Wiesmann ◽  
Laurent Caplette ◽  
Verena Willenbockel ◽  
Frédéric Gosselin ◽  
Melissa L.-H. Võ
Keyword(s):  
Time Course ◽  
Task Characteristics ◽  
Scene Categorization ◽  
Fine Grained ◽  
Spatial Frequencies ◽  
Outdoor Scenes ◽  
Indoor Scenes ◽  
Fine Pattern ◽  
Late Stages ◽  
Basic Level

AbstractHuman observers can quickly and accurately categorize scenes. This remarkable ability is related to the usage of information at different spatial frequencies (SFs) following a coarse-to-fine pattern: Low SFs, conveying coarse layout information, are thought to be used earlier than high SFs, representing more fine-grained information. Alternatives to this pattern have rarely been considered. Here, we probed all possible SF usage strategies randomly with high resolution in both the SF and time dimensions at two categorization levels. We show that correct basic-level categorizations of indoor scenes are linked to the sampling of relatively high SFs, whereas correct outdoor scene categorizations are predicted by an early use of high SFs and a later use of low SFs (fine-to-coarse pattern of SF usage). Superordinate-level categorizations (indoor vs. outdoor scenes) rely on lower SFs early on, followed by a shift to higher SFs and a subsequent shift back to lower SFs in late stages. In summary, our results show no consistent pattern of SF usage across tasks and only partially replicate the diagnostic SFs found in previous studies. We therefore propose that SF sampling strategies of observers differ with varying stimulus and task characteristics, thus favouring the notion of flexible SF usage.

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