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Top-down modulation of visual processing and knowledge after 250 ms supports object constancy of category decisions.

Schendan HE, Ganis G - Front Psychol (2015)

Bottom Line: N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only.The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex.Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, Cognition Institute, University of Plymouth Plymouth, UK.

ABSTRACT
People categorize objects more slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT) theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger impoverishment effects for real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a) word meaning in temporal cortex during the N400, (b) internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600), and (c) response related activity in posterior cingulate during an anterior slow wave (SW) after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition.

No MeSH data available.


ERP effects of impoverishment and object type with common average reference. As in Figure 3, grand average ERPs are plotted at all sites, but, in order to compare with other work, the reference was computed using the average of all scalp sites (i.e., the “average reference”), and ERPs were instead plotted positive up. ERP effects of impoverishment (more [MI], less [LI] impoverished) and object type (real, pseudo) are shown. Compared with Figure 3, with the average reference, here, the parietal P600 inverts polarity over lateral frontal and frontopolar sites to an N600, especially at the right. The late SW from 500 to 900 ms has an occipital distribution that inverts polarity over frontocentral sites near the midline, and is larger over the left hemisphere. Note, with the common average reference, the N400 pattern (gray shadow) cannot be discerned from the overlapping N3 and P600 times, highlighting the importance of using the same reference sites across studies to identify components and draw conclusions; studies analyzing data using the common average reference may misattribute N3 and/or P600 effects to the N400.
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Figure 4: ERP effects of impoverishment and object type with common average reference. As in Figure 3, grand average ERPs are plotted at all sites, but, in order to compare with other work, the reference was computed using the average of all scalp sites (i.e., the “average reference”), and ERPs were instead plotted positive up. ERP effects of impoverishment (more [MI], less [LI] impoverished) and object type (real, pseudo) are shown. Compared with Figure 3, with the average reference, here, the parietal P600 inverts polarity over lateral frontal and frontopolar sites to an N600, especially at the right. The late SW from 500 to 900 ms has an occipital distribution that inverts polarity over frontocentral sites near the midline, and is larger over the left hemisphere. Note, with the common average reference, the N400 pattern (gray shadow) cannot be discerned from the overlapping N3 and P600 times, highlighting the importance of using the same reference sites across studies to identify components and draw conclusions; studies analyzing data using the common average reference may misattribute N3 and/or P600 effects to the N400.

Mentions: The aim was to determine when impoverishment and object type interact such that the impoverishment effect is larger for real than pseudo objects. Table 1 summarizes ERP results, which were most consistent with late parietal-prefrontal PHT, MUSI, and decision theories. After 200 ms, impoverishment affected knowledge activation, modulating the N3 complex, N400, P600, and SW (Figures 3, 4); note, as results suggested no distinct LPC effects, henceforth, we refer only to the P600 and the SW.


Top-down modulation of visual processing and knowledge after 250 ms supports object constancy of category decisions.

Schendan HE, Ganis G - Front Psychol (2015)

ERP effects of impoverishment and object type with common average reference. As in Figure 3, grand average ERPs are plotted at all sites, but, in order to compare with other work, the reference was computed using the average of all scalp sites (i.e., the “average reference”), and ERPs were instead plotted positive up. ERP effects of impoverishment (more [MI], less [LI] impoverished) and object type (real, pseudo) are shown. Compared with Figure 3, with the average reference, here, the parietal P600 inverts polarity over lateral frontal and frontopolar sites to an N600, especially at the right. The late SW from 500 to 900 ms has an occipital distribution that inverts polarity over frontocentral sites near the midline, and is larger over the left hemisphere. Note, with the common average reference, the N400 pattern (gray shadow) cannot be discerned from the overlapping N3 and P600 times, highlighting the importance of using the same reference sites across studies to identify components and draw conclusions; studies analyzing data using the common average reference may misattribute N3 and/or P600 effects to the N400.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4584963&req=5

Figure 4: ERP effects of impoverishment and object type with common average reference. As in Figure 3, grand average ERPs are plotted at all sites, but, in order to compare with other work, the reference was computed using the average of all scalp sites (i.e., the “average reference”), and ERPs were instead plotted positive up. ERP effects of impoverishment (more [MI], less [LI] impoverished) and object type (real, pseudo) are shown. Compared with Figure 3, with the average reference, here, the parietal P600 inverts polarity over lateral frontal and frontopolar sites to an N600, especially at the right. The late SW from 500 to 900 ms has an occipital distribution that inverts polarity over frontocentral sites near the midline, and is larger over the left hemisphere. Note, with the common average reference, the N400 pattern (gray shadow) cannot be discerned from the overlapping N3 and P600 times, highlighting the importance of using the same reference sites across studies to identify components and draw conclusions; studies analyzing data using the common average reference may misattribute N3 and/or P600 effects to the N400.
Mentions: The aim was to determine when impoverishment and object type interact such that the impoverishment effect is larger for real than pseudo objects. Table 1 summarizes ERP results, which were most consistent with late parietal-prefrontal PHT, MUSI, and decision theories. After 200 ms, impoverishment affected knowledge activation, modulating the N3 complex, N400, P600, and SW (Figures 3, 4); note, as results suggested no distinct LPC effects, henceforth, we refer only to the P600 and the SW.

Bottom Line: N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only.The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex.Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs.

View Article: PubMed Central - PubMed

Affiliation: School of Psychology, Cognition Institute, University of Plymouth Plymouth, UK.

ABSTRACT
People categorize objects more slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT) theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger impoverishment effects for real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a) word meaning in temporal cortex during the N400, (b) internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600), and (c) response related activity in posterior cingulate during an anterior slow wave (SW) after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition.

No MeSH data available.