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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.


Effects of impoverishment and object type on the N400 and P600. Grand average ERPs at focal sites of the centroparietal N400 and parietal P600 plotted negative up. N400 and P600 impoverishment effects shown for (A) real objects and (B) pseudo objects. (C) N400 and P600 object type effects shown on LI and (D) MI trials, which showed no type effect. From 400 to 700 ms, impoverished-real-object effects were found on the N400 and P600. Positivity was greater on LI than MI trials, and this impoverishment effect was larger for real than pseudo objects, which showed no such effect on the N400. The P600 was the first ERP to show impoverishment effects for both real and pseudo objects and in the same direction.
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Figure 6: Effects of impoverishment and object type on the N400 and P600. Grand average ERPs at focal sites of the centroparietal N400 and parietal P600 plotted negative up. N400 and P600 impoverishment effects shown for (A) real objects and (B) pseudo objects. (C) N400 and P600 object type effects shown on LI and (D) MI trials, which showed no type effect. From 400 to 700 ms, impoverished-real-object effects were found on the N400 and P600. Positivity was greater on LI than MI trials, and this impoverishment effect was larger for real than pseudo objects, which showed no such effect on the N400. The P600 was the first ERP to show impoverishment effects for both real and pseudo objects and in the same direction.

Mentions: Focal results demonstrated that the N400 was less negative for LI real objects than all other stimuli, demonstrating impoverished-real-object effects (Figures 3, 4, 6). Specifically, the results (Table 3) showed significant impoverishment effects at centroparietal pair 47–48 from 400 to 500 ms, though type effects and the impoverishment by type interaction were marginal. Planned contrasts (Table 3) supported the critical interaction, as impoverishment was significant for real objects only, and type was significant for LI stimuli only. Notably, while the earlier frontal N3 showed type effects for both MI and LI stimuli, type effects between 400 and 700 ms at the parietal N400 and P600 sites, occurred only for LI objects, dissociating the frontal and parietal ERPs.


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

Schendan HE, Ganis G - Front Psychol (2015)

Effects of impoverishment and object type on the N400 and P600. Grand average ERPs at focal sites of the centroparietal N400 and parietal P600 plotted negative up. N400 and P600 impoverishment effects shown for (A) real objects and (B) pseudo objects. (C) N400 and P600 object type effects shown on LI and (D) MI trials, which showed no type effect. From 400 to 700 ms, impoverished-real-object effects were found on the N400 and P600. Positivity was greater on LI than MI trials, and this impoverishment effect was larger for real than pseudo objects, which showed no such effect on the N400. The P600 was the first ERP to show impoverishment effects for both real and pseudo objects and in the same direction.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 6: Effects of impoverishment and object type on the N400 and P600. Grand average ERPs at focal sites of the centroparietal N400 and parietal P600 plotted negative up. N400 and P600 impoverishment effects shown for (A) real objects and (B) pseudo objects. (C) N400 and P600 object type effects shown on LI and (D) MI trials, which showed no type effect. From 400 to 700 ms, impoverished-real-object effects were found on the N400 and P600. Positivity was greater on LI than MI trials, and this impoverishment effect was larger for real than pseudo objects, which showed no such effect on the N400. The P600 was the first ERP to show impoverishment effects for both real and pseudo objects and in the same direction.
Mentions: Focal results demonstrated that the N400 was less negative for LI real objects than all other stimuli, demonstrating impoverished-real-object effects (Figures 3, 4, 6). Specifically, the results (Table 3) showed significant impoverishment effects at centroparietal pair 47–48 from 400 to 500 ms, though type effects and the impoverishment by type interaction were marginal. Planned contrasts (Table 3) supported the critical interaction, as impoverishment was significant for real objects only, and type was significant for LI stimuli only. Notably, while the earlier frontal N3 showed type effects for both MI and LI stimuli, type effects between 400 and 700 ms at the parietal N400 and P600 sites, occurred only for LI objects, dissociating the frontal and parietal ERPs.

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.