Most vertebrates, including humans, exhibit a remarkable ability to visually process biological motion. However, our understanding of the early visual processing of biological motion in humans, particularly involving subcortical pathways, and the conserved neural mechanisms across species remains limited.

Recently, an innovative cross-species comparative study, published in Nature Communications, utilized high-field (3T) and ultra-high-field (7T) functional magnetic resonance imaging (fMRI) to investigate the role of the superior colliculus in the visual processing of biological motion in both humans and macaque monkeys. This study was conducted by a collaborative team from the Institute of Biophysics and the Institute of Psychology at the Chinese Academy of Sciences.

Researchers recorded superior colliculus responses in humans and macaque monkeys observing local biological motion information. They found that biological motion elicited stronger neural activation in the superior colliculus of both species compared to control conditions.

Using 7T fMRI, the researchers further segmented signals from the human superior colliculus based on surface depth. They observed that the neural activation induced by biological motion was strongest at the superficial layers of the superior colliculus and gradually weakened with increasing depth until disappearing.

The team also employed dynamic causal modeling (DCM) to explore the relationship between the human superior colliculus and other brain regions involved in biological motion processing. Their analysis revealed a functional connectivity pathway for the visual transmission of biological motion information, originating in the superior colliculus, passing through the middle temporal visual complex (MT+), and culminating in the posterior superior temporal sulcus (pSTS).

This study identified conserved neural mechanisms for processing biological motion in the superior colliculus across species, demonstrating that primates begin processing biological motion at the early stages of visual processing.

Figure (a-b) Schematic illustration of biological motion. (c-d) Human superior colliculus responses to biological motion. (e) Macaque monkey superior colliculus responses to biological motion.

(Image by LIU Ning's group)

Article link: https://www.nature.com/articles/s41467-024-53968-x

Contact: LIU Ning

Institute of Biophysics, Chinese Academy of Sciences

Beijing 100101, China

Email: liuning@ibp.ac.cn

(Reported by Prof. LIU Ning's group)