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Age-Related Differences in Spatial Frequency Processing during Scene Categorization.

Ramanoël S, Kauffmann L, Cousin E, Dojat M, Peyrin C - PLoS ONE (2015)

Bottom Line: Behavioral results revealed performance degradation for elderly participants only when categorizing HSF scenes.Elderly participants showed activation only in the anterior part of the occipital lobe for LSF scenes (compared to HSF), but not significant activation for HSF (compared to LSF).Activation of temporo-parietal regions was greater in elderly participants irrespective of spatial frequencies.

View Article: PubMed Central - PubMed

Affiliation: Univ. Grenoble Alpes, LPNC, F-38000 Grenoble, France; CNRS, LPNC, F-38000 Grenoble, France; Univ. Grenoble Alpes, GIN, F-38000 Grenoble, France.

ABSTRACT
Visual analysis of real-life scenes starts with the parallel extraction of different visual elementary features at different spatial frequencies. The global shape of the scene is mainly contained in low spatial frequencies (LSF), and the edges and borders of objects are mainly contained in high spatial frequencies (HSF). The present fMRI study investigates the effect of age on the spatial frequency processing in scenes. Young and elderly participants performed a categorization task (indoor vs. outdoor) on LSF and HSF scenes. Behavioral results revealed performance degradation for elderly participants only when categorizing HSF scenes. At the cortical level, young participants exhibited retinotopic organization of spatial frequency processing, characterized by medial activation in the anterior part of the occipital lobe for LSF scenes (compared to HSF), and the lateral activation in the posterior part of the occipital lobe for HSF scenes (compared to LSF). Elderly participants showed activation only in the anterior part of the occipital lobe for LSF scenes (compared to HSF), but not significant activation for HSF (compared to LSF). Furthermore, a ROI analysis revealed that the parahippocampal place area, a scene-selective region, was less activated for HSF than LSF for elderly participants only. Comparison between groups revealed greater activation of the right inferior occipital gyrus in young participants than in elderly participants for HSF. Activation of temporo-parietal regions was greater in elderly participants irrespective of spatial frequencies. The present findings indicate a specific low-contrasted HSF deficit for normal elderly people, in association with an occipito-temporal cortex dysfunction, and a functional reorganization of the categorization of filtered scenes.

No MeSH data available.


(a) Examples of scenes belonging to two different categories (outdoors and indoors) with the mean amplitude spectrum of each category. On the amplitude spectrum images, low spatial frequencies are close to the center and high spatial frequencies are on the periphery. Vertical orientations are represented on the x-axis and horizontal orientations on the y-axis. (b) Example of non-filtered scenes (NF), low-spatial frequency scenes (LSF) below 0.5, 1, and 2 cycles per degree (cpd), and high-spatial frequency scenes (HSF) above 3, 6, and 12 cpd.The mask used is also presented (bottom). It should be noted that the perception of spatial frequencies could be affected by picture reduction of scenes for illustrative purposes. In the experiment, picture size was about 10 times bigger than in this figure.
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pone.0134554.g001: (a) Examples of scenes belonging to two different categories (outdoors and indoors) with the mean amplitude spectrum of each category. On the amplitude spectrum images, low spatial frequencies are close to the center and high spatial frequencies are on the periphery. Vertical orientations are represented on the x-axis and horizontal orientations on the y-axis. (b) Example of non-filtered scenes (NF), low-spatial frequency scenes (LSF) below 0.5, 1, and 2 cycles per degree (cpd), and high-spatial frequency scenes (HSF) above 3, 6, and 12 cpd.The mask used is also presented (bottom). It should be noted that the perception of spatial frequencies could be affected by picture reduction of scenes for illustrative purposes. In the experiment, picture size was about 10 times bigger than in this figure.

Mentions: Stimuli were elaborated using the image processing toolbox on MATLAB (Mathworks Inc., Sherborn, MA, USA). Each scene was filtered with three low-pass filters, with cutoff frequencies corresponding to 0.5, 1, and 2 cycles per degree (cpd; i.e. 12, 24, 49 cycles per image) and three high-pass filters with cutoff frequencies corresponding to 3, 6, and 12 cpd (i.e. 71, 144, 293 cycles per image), or left unfiltered (NF). Cut-off frequencies followed a logarithmic scale in order to obtain a better sampling of the amplitude spectrum of natural scenes (see [58] for a similar procedure). Furthermore, these values were chosen in order to include cut-off frequencies of 2 cpd for LSF and 6 cpd for HSF, as used in Schyns & Oliva’s pioneer study on spatial frequency processing during scene perception [10]. The resulting images were then normalized to obtain a mean luminance equal to 128 on a grey-level scale ranging from 0 to 256. This resulted in 7 versions of each scene (1 NF, 3 LSF and 3 HSF, see Fig 1). Stimuli were displayed using E-prime software (E-prime Psychology Software Tools Inc., Pittsburgh, USA) and back-projected onto a translucent screen positioned at the rear of the magnet. Participants viewed this screen at a distance of about 222 cm via a mirror fixed on the head coil. We used a backward mask, built with 1/f white noise, to prevent retinal persistence of the scene.


Age-Related Differences in Spatial Frequency Processing during Scene Categorization.

Ramanoël S, Kauffmann L, Cousin E, Dojat M, Peyrin C - PLoS ONE (2015)

(a) Examples of scenes belonging to two different categories (outdoors and indoors) with the mean amplitude spectrum of each category. On the amplitude spectrum images, low spatial frequencies are close to the center and high spatial frequencies are on the periphery. Vertical orientations are represented on the x-axis and horizontal orientations on the y-axis. (b) Example of non-filtered scenes (NF), low-spatial frequency scenes (LSF) below 0.5, 1, and 2 cycles per degree (cpd), and high-spatial frequency scenes (HSF) above 3, 6, and 12 cpd.The mask used is also presented (bottom). It should be noted that the perception of spatial frequencies could be affected by picture reduction of scenes for illustrative purposes. In the experiment, picture size was about 10 times bigger than in this figure.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543582&req=5

pone.0134554.g001: (a) Examples of scenes belonging to two different categories (outdoors and indoors) with the mean amplitude spectrum of each category. On the amplitude spectrum images, low spatial frequencies are close to the center and high spatial frequencies are on the periphery. Vertical orientations are represented on the x-axis and horizontal orientations on the y-axis. (b) Example of non-filtered scenes (NF), low-spatial frequency scenes (LSF) below 0.5, 1, and 2 cycles per degree (cpd), and high-spatial frequency scenes (HSF) above 3, 6, and 12 cpd.The mask used is also presented (bottom). It should be noted that the perception of spatial frequencies could be affected by picture reduction of scenes for illustrative purposes. In the experiment, picture size was about 10 times bigger than in this figure.
Mentions: Stimuli were elaborated using the image processing toolbox on MATLAB (Mathworks Inc., Sherborn, MA, USA). Each scene was filtered with three low-pass filters, with cutoff frequencies corresponding to 0.5, 1, and 2 cycles per degree (cpd; i.e. 12, 24, 49 cycles per image) and three high-pass filters with cutoff frequencies corresponding to 3, 6, and 12 cpd (i.e. 71, 144, 293 cycles per image), or left unfiltered (NF). Cut-off frequencies followed a logarithmic scale in order to obtain a better sampling of the amplitude spectrum of natural scenes (see [58] for a similar procedure). Furthermore, these values were chosen in order to include cut-off frequencies of 2 cpd for LSF and 6 cpd for HSF, as used in Schyns & Oliva’s pioneer study on spatial frequency processing during scene perception [10]. The resulting images were then normalized to obtain a mean luminance equal to 128 on a grey-level scale ranging from 0 to 256. This resulted in 7 versions of each scene (1 NF, 3 LSF and 3 HSF, see Fig 1). Stimuli were displayed using E-prime software (E-prime Psychology Software Tools Inc., Pittsburgh, USA) and back-projected onto a translucent screen positioned at the rear of the magnet. Participants viewed this screen at a distance of about 222 cm via a mirror fixed on the head coil. We used a backward mask, built with 1/f white noise, to prevent retinal persistence of the scene.

Bottom Line: Behavioral results revealed performance degradation for elderly participants only when categorizing HSF scenes.Elderly participants showed activation only in the anterior part of the occipital lobe for LSF scenes (compared to HSF), but not significant activation for HSF (compared to LSF).Activation of temporo-parietal regions was greater in elderly participants irrespective of spatial frequencies.

View Article: PubMed Central - PubMed

Affiliation: Univ. Grenoble Alpes, LPNC, F-38000 Grenoble, France; CNRS, LPNC, F-38000 Grenoble, France; Univ. Grenoble Alpes, GIN, F-38000 Grenoble, France.

ABSTRACT
Visual analysis of real-life scenes starts with the parallel extraction of different visual elementary features at different spatial frequencies. The global shape of the scene is mainly contained in low spatial frequencies (LSF), and the edges and borders of objects are mainly contained in high spatial frequencies (HSF). The present fMRI study investigates the effect of age on the spatial frequency processing in scenes. Young and elderly participants performed a categorization task (indoor vs. outdoor) on LSF and HSF scenes. Behavioral results revealed performance degradation for elderly participants only when categorizing HSF scenes. At the cortical level, young participants exhibited retinotopic organization of spatial frequency processing, characterized by medial activation in the anterior part of the occipital lobe for LSF scenes (compared to HSF), and the lateral activation in the posterior part of the occipital lobe for HSF scenes (compared to LSF). Elderly participants showed activation only in the anterior part of the occipital lobe for LSF scenes (compared to HSF), but not significant activation for HSF (compared to LSF). Furthermore, a ROI analysis revealed that the parahippocampal place area, a scene-selective region, was less activated for HSF than LSF for elderly participants only. Comparison between groups revealed greater activation of the right inferior occipital gyrus in young participants than in elderly participants for HSF. Activation of temporo-parietal regions was greater in elderly participants irrespective of spatial frequencies. The present findings indicate a specific low-contrasted HSF deficit for normal elderly people, in association with an occipito-temporal cortex dysfunction, and a functional reorganization of the categorization of filtered scenes.

No MeSH data available.