Fusiform face area

The fusiform face area - FFA (meaning: spindular/spindle-shaped face area) is a part of the human visual system that is specialized for facial recognition. It is located in the Inferior temporal cortex (IT), in the fusiform gyrus (Brodmann area 37).Fusiform face area shown in red. The fusiform face area - FFA (meaning: spindular/spindle-shaped face area) is a part of the human visual system that is specialized for facial recognition. It is located in the Inferior temporal cortex (IT), in the fusiform gyrus (Brodmann area 37). The FFA is located in the ventral stream on the ventral surface of the temporal lobe on the lateral side of the fusiform gyrus. It is lateral to the parahippocampal place area. It displays some lateralization, usually being larger in the right hemisphere. The FFA was discovered and continues to be investigated in humans using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) studies. Usually, a participant views images of faces, objects, places, bodies, scrambled faces, scrambled objects, scrambled places, and scrambled bodies. This is called a functional localizer. Comparing the neural response between faces and scrambled faces will reveal areas that are face-responsive, while comparing cortical activation between faces and objects will reveal areas that are face-selective. The human FFA was first described by Justine Sergent in 1992 and later named by Nancy Kanwisher in 1997 who proposed that the existence of the FFA is evidence for domain specificity in the visual system. Studies have recently shown that the FFA is composed of functional clusters that are at a finer spatial scale than prior investigations have measured. Electrical stimulation of these functional clusters selectively distorts face perception, which is causal support for the role of these functional clusters in perceiving the facial image. While it is generally agreed that the FFA responds more to faces than to most other categories, there is debate about whether the FFA is uniquely dedicated to face processing, as proposed by Nancy Kanwisher and others, or whether it participates in the processing of other objects. The expertise hypothesis, as championed by Isabel Gauthier and others, offers an explanation for how the FFA becomes selective for faces in most people. The expertise hypothesis suggests that the FFA is a critical part of a network that is important for individuating objects that are visually similar because they share a common configuration of parts. Gauthier et al., in an adversarial collaboration with Kanwisher, tested both car and bird experts, and found some activation in the FFA when car experts were identifying cars and when bird experts were identifying birds. This finding has been replicated, and expertise effects in the FFA have been found for other categories such as chess displays and x-rays. Recently, it was found that the thickness of the cortex in the FFA predicts the ability to recognize faces as well as vehicles. A 2009 magnetoencephalography study found that objects incidentally perceived as faces, an example of pareidolia, evoke an early (165-millisecond) activation in the FFA, at a time and location similar to that evoked by faces, whereas other common objects do not evoke such activation. This activation is similar to a face-specific ERP component N170. The authors suggest that face perception evoked by face-like objects is a relatively early process, and not a late cognitive reinterpretation phenomenon. One case study of agnosia provided evidence that faces are processed in a special way. A patient known as C. K., who suffered brain damage as a result of a car accident, later developed object agnosia. He experienced great difficulty with basic-level object recognition, also extending to body parts, but performed very well at recognizing faces. A later study showed that C. K. was unable to recognize faces that were inverted or otherwise distorted, even in cases where they could easily be identified by normal subjects. This is taken as evidence that the fusiform face area is specialized for processing faces in a normal orientation. Studies using functional magnetic resonance imaging and electrocorticography have demonstrated that activity in the FFA codes for individual faces and the FFA is tuned for behaviorally relevant facial features. An electrocorticography study found that the FFA is involved in multiple stages of face processing, continuously from when people see a face until they respond to it, demonstrating the dynamic and important role the FFA plays as part of the face perception network. Another study found that there is stronger activity in the FFA when a person sees a familiar face as opposed to an unfamiliar one. Participants were shown different pictures of faces that either had the same identity, familiar, or faces with separate identities, or unfamiliar. It found that participants were more accurate at matching familiar faces than unfamiliar ones. Using an fMRI, they also found that the participants that were more accurate in identifying familiar faces had more activity in their right fusiform face area and participants that were poor at matching had less activity in their right fusiform area. The fusiform face area (FFA) is a part of the brain located in the fusiform gyrus with a debated purpose. Some researchers believe that the FFA is evolutionary purposed for face perception. Others believe that the FFA discriminates between any familiar stimuli.