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Investigating representations of facial identity in human ventral visual cortex with transcranial magnetic stimulation.

Gilaie-Dotan S, Silvanto J, Schwarzkopf DS, Rees G - Front Hum Neurosci (2010)

Bottom Line: Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different.But critically, we found no effects of TMS to either area that were modulated by identity repetition.Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London London, UK.

ABSTRACT
The occipital face area (OFA) is face-selective. This enhanced activation to faces could reflect either generic face and shape-related processing or high-level conceptual processing of identity. Here we examined these two possibilities using a state-dependent transcranial magnetic stimulation (TMS) paradigm. The lateral occipital (LO) cortex which is activated non-selectively by various types of objects served as a control site. We localized OFA and LO on a per-participant basis using functional MRI. We then examined whether TMS applied to either of these regions affected the ability of participants to decide whether two successively presented and physically different face images were of the same famous person or different famous people. TMS was applied during the delay between first and second face presentations to investigate whether neuronal populations in these regions played a causal role in mediating the behavioral effects of identity repetition. Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different. Surprisingly, TMS applied over LO (but not OFA) modulated overall RTs, compared to the No-TMS condition. But critically, we found no effects of TMS to either area that were modulated by identity repetition. Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing. Instead, these brain regions may be involved in the processing of more generic features of their preferred stimulus categories.

No MeSH data available.


Identity repetition modulation effect and LO site-specific effect as evident by shorter RTs. (A) Significant identity repetition modulation effect: Reduction in RTs (correct trials) when identity is repeated compared to different trials, regardless of the TMS site. (B) Mean RT for correct trials according to trial type and TMS site. TMS site effect for LO: LO-TMS was significantly different than No-TMS while OFA was not, and this was true for both different identity trials and repeated identity trials. Red – different identity trials, blue – repeated identity trials. Error bars, SEM.
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Figure 3: Identity repetition modulation effect and LO site-specific effect as evident by shorter RTs. (A) Significant identity repetition modulation effect: Reduction in RTs (correct trials) when identity is repeated compared to different trials, regardless of the TMS site. (B) Mean RT for correct trials according to trial type and TMS site. TMS site effect for LO: LO-TMS was significantly different than No-TMS while OFA was not, and this was true for both different identity trials and repeated identity trials. Red – different identity trials, blue – repeated identity trials. Error bars, SEM.

Mentions: A robust identity repetition modulation effect was found with faster RTs in the repeated identity trials [676 ± 34 ms (SEM)] compared to the different identity trials [730 ± 46 ms (SEM)] in the No-TMS condition and this difference was statistically significant [t(11) = 3.204, p = 0.0083, correct trials]. This significant reduction in RT was evident in all 12 participants and can be seen in Figure 3A (No-TMS condition).


Investigating representations of facial identity in human ventral visual cortex with transcranial magnetic stimulation.

Gilaie-Dotan S, Silvanto J, Schwarzkopf DS, Rees G - Front Hum Neurosci (2010)

Identity repetition modulation effect and LO site-specific effect as evident by shorter RTs. (A) Significant identity repetition modulation effect: Reduction in RTs (correct trials) when identity is repeated compared to different trials, regardless of the TMS site. (B) Mean RT for correct trials according to trial type and TMS site. TMS site effect for LO: LO-TMS was significantly different than No-TMS while OFA was not, and this was true for both different identity trials and repeated identity trials. Red – different identity trials, blue – repeated identity trials. Error bars, SEM.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2903189&req=5

Figure 3: Identity repetition modulation effect and LO site-specific effect as evident by shorter RTs. (A) Significant identity repetition modulation effect: Reduction in RTs (correct trials) when identity is repeated compared to different trials, regardless of the TMS site. (B) Mean RT for correct trials according to trial type and TMS site. TMS site effect for LO: LO-TMS was significantly different than No-TMS while OFA was not, and this was true for both different identity trials and repeated identity trials. Red – different identity trials, blue – repeated identity trials. Error bars, SEM.
Mentions: A robust identity repetition modulation effect was found with faster RTs in the repeated identity trials [676 ± 34 ms (SEM)] compared to the different identity trials [730 ± 46 ms (SEM)] in the No-TMS condition and this difference was statistically significant [t(11) = 3.204, p = 0.0083, correct trials]. This significant reduction in RT was evident in all 12 participants and can be seen in Figure 3A (No-TMS condition).

Bottom Line: Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different.But critically, we found no effects of TMS to either area that were modulated by identity repetition.Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing.

View Article: PubMed Central - PubMed

Affiliation: Institute of Cognitive Neuroscience, University College London London, UK.

ABSTRACT
The occipital face area (OFA) is face-selective. This enhanced activation to faces could reflect either generic face and shape-related processing or high-level conceptual processing of identity. Here we examined these two possibilities using a state-dependent transcranial magnetic stimulation (TMS) paradigm. The lateral occipital (LO) cortex which is activated non-selectively by various types of objects served as a control site. We localized OFA and LO on a per-participant basis using functional MRI. We then examined whether TMS applied to either of these regions affected the ability of participants to decide whether two successively presented and physically different face images were of the same famous person or different famous people. TMS was applied during the delay between first and second face presentations to investigate whether neuronal populations in these regions played a causal role in mediating the behavioral effects of identity repetition. Behaviorally we found a robust identity repetition effect, with shorter reaction times (RTs) when identity was repeated, regardless of the fact that the pictures were physically different. Surprisingly, TMS applied over LO (but not OFA) modulated overall RTs, compared to the No-TMS condition. But critically, we found no effects of TMS to either area that were modulated by identity repetition. Thus, we found no evidence to suggest that OFA or LO contain neuronal representations selective for the identity of famous faces which play a causal role in identity processing. Instead, these brain regions may be involved in the processing of more generic features of their preferred stimulus categories.

No MeSH data available.