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

Abstract

Neuroimaging studies identify multiple face-selective areas in the human brain. 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 same videos or static images. Results showed that the rIFG, right posterior superior temporal sulcus (rpSTS) and right occipital face area (rOFA) exhibited a greater response to moving than static faces. In Experiment 3 participants (n = 18) viewed face videos in the contralateral and ipsilateral visual fields. Results showed that the rIFG and rpSTS showed no visual field bias, while the rOFA and right fusiform face area (rFFA) 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 profiles in the IFG and pSTS suggests the areas may perform similar cognitive functions, a conclusion consistent with prior 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 – 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 ).…”

TMS disruption of the lateral prefrontal cortex increases neural activity in the default mode network when naming facial expressions

“…In this session participants viewed three runs of a functional localiser task (234 seconds each) to individually identify face-selective areas. Our previous fMRI study of face processing in the lateral PFC demonstrated that a face-selective area was more commonly identified across participants in the right IFG (Nikel et al, 2022). Based on this study we targeted the same location for disruption with TMS in the current study.…”

“…TMS was delivered over the inferior frontal gyrus (IFG), a region of the lateral PFC that has been implicated in a range of face processing tasks (Chan, 2013; Ishai et al, 2002). We chose to target the right IFG because our prior study demonstrated that face-selective activity can be more reliably identified in the right hemisphere (Nikel et al, 2022).…”