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Age-related differences in spatial frequency processing during scene categorization

Louise Kauffmann
Emilie Cousin
Michel Dojat


Introduction: Real-life visual scenes are primarily processed in terms of spatial frequencies. Low spatial frequencies (LSF) convey the global shape of the scene, and high spatial frequencies (HSF) convey the edges and borders of objects. Recent neuroimaging studies have aimed to identify the cerebral regions differentially involved in LSF and HSF processing in young adults (for a recent review, Kauffman, Ramanoël, & Peyrin, 2014). However, the way spatial frequencies are processed in normal aging remains unclear. The present fMRI study investigates how the spatial frequency processing of scenes evolves with aging. Methods: Twelve young (22±3 years) and 12 elderly (64±3 years) right-handed participants performed a categorization task using large black and white photographs of scenes (indoors vs. outdoors, with a visual angle of 24°×18°) filtered in LSF (cutoff frequencies: 0.5, 1, 2 cpd), HSF (cutoff frequencies: 3, 6, 12 cpd), and non-filtered scenes, in a block-designed fMRI experiment consisting of four functional runs. Each functional scan was composed of nine 25-sec task blocks (one block per spatial frequency cut-off and three blocks of NF scenes), including 10 scenes (5 indoors and 5 outdoors), interspersed with three 25-sec blocks with a fixation dot in the center of the screen displayed against a grey background. Each scene was displayed for 100 ms, followed by a mask for 30 ms (1/f white noise) to prevent retinal persistence. Experiment was performed using a whole-body 3T Philips scanner (Achieva 3.0T TX Philips) with a 32-channel head coil at the University Hospital Center of Grenoble in France. Data analysis was performed using the general linear model for block designs in SPM12b (Wellcome Department of Imaging Neuroscience, London, UK). On an individual level, we first identified the brain regions involved in the processing of each spatial frequency content relative to the fixation ([LSF>fixation], [HSF>fixation], [NF>fixation]). To allow population inference, ANOVAs were performed based on individual analysis by means of a flexible-factorial design. Areas of activation were considered significant if they exceeded a voxel threshold of p<0.05 family-wise error corrected for multiple comparisons. Results: Behavioral results revealed performance degradation with aging only for HSF scenes. At the cortical level, the within-group analysis (Fig 1) revealed a retinotopic organization of spatial frequency processing in young participants. The categorization of LSF scenes (compared to HSF) activated the medial aspect of the anterior part of the occipital lobe linked to the peripheral visual fields, in accordance with the retinotopic properties of early visual areas. HSF scenes (compared to LSF) elicited activation in the posterior part of the occipital lobes linked to the fovea. Elderly participants showed activation only in the anterior part of the occipital lobe for LSF (compared to HSF) scenes. HSF scene categorization did not elicit stronger significant activation than LSF scenes. Comparison between groups (Fig 2) revealed greater activation of the right inferior occipital gyrus in young participants than in elderly participants for HSF. Activation of bilateral inferior parietal lobules and left posterior middle temporal cortex were greater in elderly participants irrespective of spatial frequencies. Note that contrasts relative to NF scenes did not reveal significant activation, and that there was no effect of cutoff frequencies. Conclusions: The present findings indicate a specific HSF deficit, in association with occipital cortex dysfunction, and a functional reorganization of the categorization of filtered scenes in the context of normal aging. The elderly participants may engage greater attentional resources and semantic processes, involving temporo-parietal regions, to compensate for their deficit in low-level vision and diminished occipital cortex activation. Our study provides support to the understanding of visual impairments in pathological aging.
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hal-01982484 , version 1 (15-01-2019)


  • HAL Id : hal-01982484 , version 1


Stephen Ramanoël, Louise Kauffmann, Emilie Cousin, Michel Dojat, Carole Peyrin. Age-related differences in spatial frequency processing during scene categorization. Organization of Human Brain Mapping, Jun 2015, Honolulu, United States. ⟨hal-01982484⟩
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