results did not depend on the specific tagging frequency assignment to faces or houses (fig. S5).
In temporal cortex, both MEG and fMRI results
showed a moderate tendency of lateralization: FFA
to the right and PPA to the left hemisphere (Fig. 2H).
The attentional effects in IFJ were slightly lateral-ized to the right.
We used Fourier transformations to extract the
phase relation between the frequency-tag response
and the stimulus on the screen, i.e., the latency of the
sensory responses (Fig. 2I). The phase lag of IFJ (cor-
responding to 208 ms) was shifted by about 25 ms
in comparison to FFA and PPA (188 and 171 ms)
(Fig. 2J and fig. S5) (20), which likely accounts for
transmission time and synaptic delays between areas.
Frequency [Hz] Lateralization
FFA/PPA phase lag [ms]
FFA PPA IFJ V1
Fig. 2. Measures of attention localization. (A) Average of the fMRI localizers for
attention-related and (B) object-related ROIs (blue: FFA, red: PPA, P < 0.001, FW error-corrected). (C and D) All subjects' individual ROIs superimposed on a standardized brain
surface (red: middle frontal gyrus; blue: inferior frontal gyrus; dashed line: BA44) and (E) on
an inflated brain. (F) Comparison of the average MEG-based (filled) and fMRI-based (outlines)
localization of face- (blue) and house-related (red) activity. (G) Spectral power in the par-ticipants' individual ROIs when attending houses (1.5 Hz, red) or faces (2.0 Hz, blue).
(H) Lateralization of the attentional effects. (I) Phase lags of the neural activity to the
physical stimuli on screen. (J) Systematic phase advancement from FFA/PPA to IFJ.
attend FACE (2.0Hz)
attend HOUSE (1.5Hz)
Fig. 1. Stimuli and attention. (A) Stimuli used in the MEG experiment (see online
methods). (B) Sequence of stimuli consisting of an overlay of two streams of objects
(faces and houses), fading in and out of a phase-scrambled noise mask at different
frequencies (1.5 and 2.0 Hz). Subjects had to attend the cued stream and report
occasional 1-back repeats. (C) Fourier-transform of the minimum norm estimate
when attending to faces (2.0 Hz) or houses (1.5 Hz, P < 0.05, FDR-corrected).