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Decoding individual natural scene representations during perception and imagery.

Johnson MR, Johnson MK - Front Hum Neurosci (2014)

Bottom Line: We found that item-specific information was represented in multiple scene-selective areas: the occipital place area (OPA), parahippocampal place area (PPA), retrosplenial cortex (RSC), and a scene-selective portion of the precuneus/intraparietal sulcus region (PCu/IPS).These results support findings from previous decoding analyses for other types of visual information and/or brain areas during imagery or working memory, and extend them to the case of visual scenes (and scene-selective cortex).This suggests that although decodable scene-relevant activity occurs in FFA during perception, FFA activity may not be a necessary (or even relevant) component of one's mental representation of visual scenes.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Yale University New Haven, CT, USA.

ABSTRACT
We used a multi-voxel classification analysis of functional magnetic resonance imaging (fMRI) data to determine to what extent item-specific information about complex natural scenes is represented in several category-selective areas of human extrastriate visual cortex during visual perception and visual mental imagery. Participants in the scanner either viewed or were instructed to visualize previously memorized natural scene exemplars, and the neuroimaging data were subsequently subjected to a multi-voxel pattern analysis (MVPA) using a support vector machine (SVM) classifier. We found that item-specific information was represented in multiple scene-selective areas: the occipital place area (OPA), parahippocampal place area (PPA), retrosplenial cortex (RSC), and a scene-selective portion of the precuneus/intraparietal sulcus region (PCu/IPS). Furthermore, item-specific information from perceived scenes was re-instantiated during mental imagery of the same scenes. These results support findings from previous decoding analyses for other types of visual information and/or brain areas during imagery or working memory, and extend them to the case of visual scenes (and scene-selective cortex). Taken together, such findings support models suggesting that reflective mental processes are subserved by the re-instantiation of perceptual information in high-level visual cortex. We also examined activity in the fusiform face area (FFA) and found that it, too, contained significant item-specific scene information during perception, but not during mental imagery. This suggests that although decodable scene-relevant activity occurs in FFA during perception, FFA activity may not be a necessary (or even relevant) component of one's mental representation of visual scenes.

No MeSH data available.


Related in: MedlinePlus

Task design. (A) On Perceive trials, participants were shown a picture of a scene along with its label for 4 s. On Image trials, participants saw only an empty frame with a label instructing which of the four scenes to imagine. The example displays shown here correspond to Experiment 1; in Experiment 2, the displays were the same except that the printed labels were removed entirely and replaced with auditorily presented recordings of the same words spoken aloud. (B) The two processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions of the task. (C) Sample ROI locations for four representative subjects, two from Experiment 1 and two from Experiment 2. Clusters are overlaid on raw functional images from that participant's data.
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Figure 1: Task design. (A) On Perceive trials, participants were shown a picture of a scene along with its label for 4 s. On Image trials, participants saw only an empty frame with a label instructing which of the four scenes to imagine. The example displays shown here correspond to Experiment 1; in Experiment 2, the displays were the same except that the printed labels were removed entirely and replaced with auditorily presented recordings of the same words spoken aloud. (B) The two processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions of the task. (C) Sample ROI locations for four representative subjects, two from Experiment 1 and two from Experiment 2. Clusters are overlaid on raw functional images from that participant's data.

Mentions: The version of the main Perception-Imagery (P-I) task used in Experiment 1 is shown in Figure 1. Before fMRI scanning, participants repeatedly viewed four scene pictures (for all participants, a beach, a desert, a field, and a house) and were instructed to memorize the details of the pictures as well as they could for later mental imagery. For the P-I task (Figure 1A), on each trial, participants were either shown one of the pictures along with its name (Perception) or simply the name of one picture (Beach, Desert, Field, or House), in which case they were instructed to form the most vivid and accurate mental image possible of that picture as long as the label was onscreen (Imagery). Thus the 2 processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions [Perceive Beach (PB), Image Beach (IB), Perceive Desert (PD), and so on] of the task (Figure 1B). These four scene pictures were intentionally selected from different sub-categories of visual scenes with relatively large differences in color, spatial composition, etc., to minimize featural confusion between images. Thus successful classification between items in this study would likely reflect information differences at some combination of the sub-category and exemplar (within sub-category) levels, somewhat limiting the granularity of information representation that could be deduced but also maximizing chances of successful classification, while using a design that could easily be extended in future studies to examine more fine-grained differences among scene exemplars (see Discussion). In this paper, we will refer to the different scenes used simply as “items” and information revealed in classification as “item-specific,” acknowledging that such information likely comprises a fusion of sub-category-specific and exemplar-specific information.


Decoding individual natural scene representations during perception and imagery.

Johnson MR, Johnson MK - Front Hum Neurosci (2014)

Task design. (A) On Perceive trials, participants were shown a picture of a scene along with its label for 4 s. On Image trials, participants saw only an empty frame with a label instructing which of the four scenes to imagine. The example displays shown here correspond to Experiment 1; in Experiment 2, the displays were the same except that the printed labels were removed entirely and replaced with auditorily presented recordings of the same words spoken aloud. (B) The two processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions of the task. (C) Sample ROI locations for four representative subjects, two from Experiment 1 and two from Experiment 2. Clusters are overlaid on raw functional images from that participant's data.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921604&req=5

Figure 1: Task design. (A) On Perceive trials, participants were shown a picture of a scene along with its label for 4 s. On Image trials, participants saw only an empty frame with a label instructing which of the four scenes to imagine. The example displays shown here correspond to Experiment 1; in Experiment 2, the displays were the same except that the printed labels were removed entirely and replaced with auditorily presented recordings of the same words spoken aloud. (B) The two processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions of the task. (C) Sample ROI locations for four representative subjects, two from Experiment 1 and two from Experiment 2. Clusters are overlaid on raw functional images from that participant's data.
Mentions: The version of the main Perception-Imagery (P-I) task used in Experiment 1 is shown in Figure 1. Before fMRI scanning, participants repeatedly viewed four scene pictures (for all participants, a beach, a desert, a field, and a house) and were instructed to memorize the details of the pictures as well as they could for later mental imagery. For the P-I task (Figure 1A), on each trial, participants were either shown one of the pictures along with its name (Perception) or simply the name of one picture (Beach, Desert, Field, or House), in which case they were instructed to form the most vivid and accurate mental image possible of that picture as long as the label was onscreen (Imagery). Thus the 2 processes (Perception, Imagery) × the 4 stimuli (Beach, Desert, Field, House) formed a total of 8 conditions [Perceive Beach (PB), Image Beach (IB), Perceive Desert (PD), and so on] of the task (Figure 1B). These four scene pictures were intentionally selected from different sub-categories of visual scenes with relatively large differences in color, spatial composition, etc., to minimize featural confusion between images. Thus successful classification between items in this study would likely reflect information differences at some combination of the sub-category and exemplar (within sub-category) levels, somewhat limiting the granularity of information representation that could be deduced but also maximizing chances of successful classification, while using a design that could easily be extended in future studies to examine more fine-grained differences among scene exemplars (see Discussion). In this paper, we will refer to the different scenes used simply as “items” and information revealed in classification as “item-specific,” acknowledging that such information likely comprises a fusion of sub-category-specific and exemplar-specific information.

Bottom Line: We found that item-specific information was represented in multiple scene-selective areas: the occipital place area (OPA), parahippocampal place area (PPA), retrosplenial cortex (RSC), and a scene-selective portion of the precuneus/intraparietal sulcus region (PCu/IPS).These results support findings from previous decoding analyses for other types of visual information and/or brain areas during imagery or working memory, and extend them to the case of visual scenes (and scene-selective cortex).This suggests that although decodable scene-relevant activity occurs in FFA during perception, FFA activity may not be a necessary (or even relevant) component of one's mental representation of visual scenes.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Yale University New Haven, CT, USA.

ABSTRACT
We used a multi-voxel classification analysis of functional magnetic resonance imaging (fMRI) data to determine to what extent item-specific information about complex natural scenes is represented in several category-selective areas of human extrastriate visual cortex during visual perception and visual mental imagery. Participants in the scanner either viewed or were instructed to visualize previously memorized natural scene exemplars, and the neuroimaging data were subsequently subjected to a multi-voxel pattern analysis (MVPA) using a support vector machine (SVM) classifier. We found that item-specific information was represented in multiple scene-selective areas: the occipital place area (OPA), parahippocampal place area (PPA), retrosplenial cortex (RSC), and a scene-selective portion of the precuneus/intraparietal sulcus region (PCu/IPS). Furthermore, item-specific information from perceived scenes was re-instantiated during mental imagery of the same scenes. These results support findings from previous decoding analyses for other types of visual information and/or brain areas during imagery or working memory, and extend them to the case of visual scenes (and scene-selective cortex). Taken together, such findings support models suggesting that reflective mental processes are subserved by the re-instantiation of perceptual information in high-level visual cortex. We also examined activity in the fusiform face area (FFA) and found that it, too, contained significant item-specific scene information during perception, but not during mental imagery. This suggests that although decodable scene-relevant activity occurs in FFA during perception, FFA activity may not be a necessary (or even relevant) component of one's mental representation of visual scenes.

No MeSH data available.


Related in: MedlinePlus