Biological motion perception

Currently a large topic of research, many different models of biological motion/perception have been proposed. The following models have shown that both form and motion are important components of biological motion perception. However, to what extent each of the components play is contrasted upon the models. Research in this area seeks to identify the specific brain regions or circuits responsible for processing the information which the visual system perceives in the world. And in this case, specifically recognizing motion created by biological agents. The most precise research is done using single-cell recordings in the primate brain. This research has yielded areas important to motion perception in primates such as area MT (middle temporal visual area), also referred to as V5, and area MST (medial superior temporal area). These areas contain cells characterized as direction cells, expansion/contraction cells, and rotation cells, which react to certain classes of movement. Additionally, research on human participants is being conducted as well. While single-cell recording is not conducted on humans, this research uses neuroimaging methods such as fMRI, PET, EEG/ERP to collect information on what brain areas become active when executing biological motion perception tasks, such as viewing point light walker stimuli. Areas uncovered from this type of research are the dorsal visual pathway, extrastriate body area, fusiform gyrus, superior temporal sulcus, and premotor cortex. The dorsal visual pathway (sometimes referred to as the “where” pathway), as contrasted with the ventral visual pathway (“what” pathway), has been shown to play a significant role in the perception of motion cues. While the ventral pathway is more responsible for form cues. Valuable information can also be learned from cases where a patient has suffered from some sort of neurological damage and consequently loses certain functionalities of neural processing. One patient with bilateral lesions that included the human homologue of area MT, lost their ability to see biological motion when the stimulus was embedded in noise, a task which the average observer is able to complete. Another study on stroke patients sustaining lesions to their superior temporal and premotor frontal areas showed deficits in their processing of biological motion stimuli, thereby implicating these areas as important to that perception process. A case study conducted on a patient with bilateral lesions involving the posterior visual pathways and effecting the lateral parietal-temporal-occipital cortex struggled with early motion tasks, and yet was able to perceive the biological motion of a point light walker, a higher-order task. This may be due to the fact that area V3B and area KO were still intact, suggesting their possible roles in biological motion perception.