Measuring the response to visually presented faces in the human lateral prefrontal cortex

Abstract

Neuroimaging studies have identified multiple face-selective areas. In the current study we compared the functional response of the face area in the lateral prefrontal cortex to that of other face-selective areas. In Experiment 1 participants (N=32) were scanned viewing videos containing faces, bodies, scenes, objects, and scrambled objects. We identified a face-selective area in the right inferior frontal gyrus (rIFG). In Experiment 2 participants (N=24) viewed the videos or static images. Results showed that the rIFG, posterior superior temporal sulcus (pSTS) and occipital face area (OFA) exhibited a greater response to moving than static faces. In Experiment 3 participants (N=18) viewed face videos presented in the contralateral and ipsilateral visual fields. Results showed that the face areas in the IFG and pSTS responded equally to faces in both visual fields, while the OFA and fusiform face area (FFA) showed a contralateral bias. These experiments suggest two conclusions; firstly, in all three experiments the face area in the IFG was not as reliably identified as face areas in the occipitotemporal cortex. Secondly, the similarity of the response patterns in the IFG and pSTS face areas suggests that the areas are functionally connected, a conclusion consistent with neuroanatomical and functional connectivity evidence.

Moving and static faces, bodies, objects and scenes are differentially represented across the three visual pathways

“…The pSTS and PFC ROIs were also larger when identified with moving stimuli. These results are consistent with some prior studies (Fox et al, 2009; Nikel et al, 2022; Pitcher, Dilks, et al, 2011; Pitcher et al, 2019) but it is important to note that other studies have demonstrated that the FFA can also exhibit a greater response to moving faces than static faces (Pilz et al, 2011; Schultz & Pilz, 2009).…”

“…A total of thirty participants (20 females; age range 18 to 48 years old; mean age 23 years) with normal, or corrected-to-normal, vision gave informed consent as directed by the Ethics committee at the University of York. Data from 24 participants was collected for a previous fMRI experiment (Nikel et al, 2022) and re-analysed for the current study.…”

Multivariate functional neuroimaging analyses reveal that strength-dependent face expectations are represented in higher-level face-identity areas

“…Notably, though we focused on face-sensitive regions in the right hemisphere, because activations in face regions are often stronger, more consistent, and larger in the right hemisphere 30,56,57,70 , analogous to observations from brain lesions that the right hemisphere is specialized for face processing 71,72 , similar face-related activations were found in the left hemisphere and we do not rule out that these also play a role in processing and generating face expectations. Furthermore, faces are processed in several other regions outside the ventral stream, for example, in the frontal lobe 73,74 or the superior temporal sulcus (STS), which responds stronger to dynamic than static face stimuli [75][76][77] . An exploratory analysis of representations of expected and presented faces, measured in form of multivoxel fMRI patterns in the STS, did not reveal any influence of face expectations in the current study (see Supplementary Note 1).…”