On the Hypothesis of a Differential Hemispheric Capacity for Spatial Frequency Analysis (original) (raw)
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Spatial Frequency and Right Hemisphere: An Electrophysiological Investigation
Brain and Cognition, 1998
The influence of the spatial frequency of visual stimuli on hemispheric asymmetry has been studied with visual evoked potentials (VEP). Nineteen different sinusoidal gratings (19 SF from 1 to 10 cpd) were presented in an ON-OFF mode to five right-handed subjects. The amplitude of the VEPs and the latency of the first positive component (C1) were analyzed. The results show that in the low range of spatial frequencies, the latency and the amplitude of C1 are similar in both hemispheres. At medium to high spatial frequencies, the VEPs on the right hemisphere (RH) present shorter latencies and larger amplitudes than those on the left hemisphere (LH). These results, discussed in relation to the directional differences in the time of callosal interhemispheric transfer, strengthen the idea that the RH is relatively more sensitive than the LH to the spatial component of the visual stimuli.
Effect of temporal constraints on hemispheric asymmetries during spatial frequency processing
Brain and Cognition, 2006
Studies on functional hemispheric asymmetries have suggested that the right vs. left hemisphere should be predominantly involved in low vs. high spatial frequency (SF) analysis, respectively. By manipulating exposure duration of filtered natural scene images, we examined whether the temporal characteristics of SF analysis (i.e., the temporal precedence of low on high spatial frequencies) may interfere with hemispheric specialization. Results showed the classical hemispheric specialization pattern for brief exposure duration and a trend to a right hemisphere advantage irrespective of the SF content for longer exposure duration. The present study suggests that the hemispheric specialization pattern for visual information processing should be considered as a dynamic system, wherein the superiority of one hemisphere over the other could change according to the level of temporal constraints: the higher the temporal constraints of the task, the more the hemispheres are specialized in SF processing.
Hemispheric specialization for spatial frequency processing in the analysis of natural scenes
Brain and Cognition, 2003
Experimental data coming from visual cognitive sciences suggest that visual analysis starts with a parallel extraction of different visual attributes at different scales/frequencies. Neuropsychological and functional imagery data have suggested that each hemisphere (at the level of temporo-parietal junctions-TPJ) could play a key role in spatial frequency processing: The right TPJ should predominantly be involved in low spatial frequency (LFs) analysis and the left TPJ in high spatial frequency (HFs) analysis. Nevertheless, this functional hypothesis had been inferred from data obtained when using the hierarchical form paradigm, without any explicit spatial frequency manipulation per se. The aims of this research are (i) to investigate, in healthy subjects, the hemispheric asymmetry hypothesis with an explicit manipulation of spatial frequencies of natural scenes and (ii) to examine whether the Ôprecedence effectÕ (the relative rapidity of LFs and HFs processing) depends on the visual field of scene presentation or not. For this purpose, participants were to identify either non-filtered or LFs and HFs filtered target scene displayed either in the left, central, or right visual field. Results showed a hemispheric specialization for spatial frequency processing and different Ôprecedence effectsÕ depending on the visual field of presentation.
Hemispheric Asymmetries for Spatial Frequency Discrimination in a Selective Attention Task
Brain and Cognition, 1997
Hemispheric specialization for spatial frequency processing was investigated by measuring reaction times to sinusoidal gratings in 12 healthy subjects. Stimuli of 1.5, 3, and 6 c/deg were randomly presented at two peripheral locations in the left (LVF) and right (RVF) upper visual hemifields during a selective attention task. Subjects were instructed to pay covert attention and to respond to a frequency in a given hemifield ignoring all other stimuli. Results showed that RTs were significantly faster at LVF than RVF for low frequency gratings, and at RVF than LVF for high frequency gratings. Furthermore, RTs were faster to 6 than 1.
On the nonrelation between spatial frequency and cerebral hemispheric competence
Brain and Cognition, 1991
The hypothesis that the two cerebral hemispheres are specialized for processing different visual spatial frequencies is discussed in reference to Christman's (1989) review. It is suggested that the relevant results from every study reviewed by Christman which support the hypothesis can also be explained in terms of the total amount of visible information or energy contained in a visual stimulus, and the right hemisphere's relative resistance to information degradation. A recent study provides evidence in support of this total visible information/energy hypothesis, and appropriate measures of information/energy are discussed. Furthermore, results from the studies reviewed may reflect response bias and not hemispheric specialization or competence. The few studies which examine response bias support such an interpretation.
Journal of Cognitive Neuroscience, 2004
Right-handed participants performed categorical and coordinate spatial relation tasks on stimuli presented either to the left visual field-right hemisphere (LVF-RH) or to the right visual field-left hemisphere (RVF-LH). The stimuli were either unfiltered or low-pass filtered (i.e., devoid of high spatial frequency content). Consistent with previous studies, the unfiltered condition produced a significant RVF-LH advantage for the categorical task and an LVF-RH advantage for the coordinate task. Low-pass filtering eliminated this Task × Visual Field interaction; thus, the RVF-LH advantage disappeared for the categorical task. The present results suggest that processing of high spatial frequency contributes to the left hemispheric advantage for categorical spatial processing.
Hemispheric Asymmetry in Visual Processing: An ERP Study on Spatial Frequency Gratings
A hemispheric asymmetry is known for the processing of global vs. local visual information. In this study, we investigated the existence of a hemispheric asymmetry for visual processing of low vs. high spatial frequency gratings. Event-related potentials were recorded in a group of healthy right-handed volunteers from 30 scalp sites. Six types of stimuli (1.5, 3 and 6 c/deg gratings) were randomly flashed 180 times in the left and right upper hemi-fields. Stimulus duration was 80 ms and ISI ranged between 850-1000 ms. Participants had to pay attention and respond to targets based on their spatial frequency and location, or to passively look at the stimuli. C1 and P1 visual responses, as well as a later Selection negativity and a P300 components of ERPs were quantified and subjected to repeated-measure ANOVAs. Overall, performance was faster for the RVF, thus suggesting a left hemispheric advantage for attentional selection of local elements. Similarly, the analysis of mean area ampl...
Hemispheric Differences for Global and Local Processing: Effect of Stimulus Size and Sparsity
The Spanish journal of psychology, 2009
The present experiment was designed to assess the hemispheric differences for global and local processing in healthy participants under different conditions of stimuli visibility, by means of varying the size and sparsity. Three different sizes and three different matrixes of hierarchical stimuli were introduced. Stimuli consisted of incomplete squares with one side missing. Participants were asked to carry out an orientation classification task (left/right), indicating the orientation of the square opening either at global or local levels. The results do not support the hemispheric differences for global and local processing, showing the same efficiency of right and left hemispheres for analyzing global and local information. Nevertheless, other results found are consistent with the hypothesis of right hemisphere superiority under degraded stimulus conditions.
Hemispheric differences in tactuo-spatial processing
Neuropsychologia, 1978
A tactual recognition task employing six random forms presented in each of eight 45 ° relative disorientations was given to ten normal blindfolded subjects. A consistent right hemisphere advantage was obtained. Pattern of scores, however, was similar for both hemispheres, suggesting that: (a) the right hemisphere is doing the processing; (b) the left hemisphere has access to the results of this; (c) the right hemisphere has access to the information gathered by the left hemisphere. The results suggest that information loss occurs during hemispheric transfer.