Saccades to novelty drive widespread brain activation

The brain is particularly receptive to changes in the visual environment, whether slight alteration in the luminance of a computer screen, moving the eyes from one point to another while looking at an object (i.e., making saccades), or watching a movie. The visual changes induced by visual stimuli activate various brain regions. 

Until now, different types of visual changes - motion, saccades, and dynamic stimuli - have been mainly studied in isolation. A group of scientists from the City College of New York (NY, USA), led by the first author Maximilian Nentwich (Ph.D.), aimed to understand how a combination of visual changes affects brain activity while watching movies. 

The scientists recorded simultaneous intracranial electroencephalography (iEEG) and eye movements from over 6,000 contacts in 23 patients with epilepsy who were watching movie clips. iEEG allows the registration of brain activity by implanting electrodes directly into the brain. The scientists explored how three visual changes found in movies - stimulus motion, saccades, and film cuts rich in novel information - would affect brain activity. 

The results showed widespread brain activity while viewing film cuts and making saccades. In contrast, viewing a stimulus in motion evoked neuronal activity in more confined areas of the visual brain regions. The authors discuss that the widespread brain response to film cuts and saccades is likely linked to processing the meaning, faces, or novelty of information shown in the movies. When the cuts occurred at points in the film where significant events or changes in meaning occurred, the temporal and medial temporal brain lobes showed heightened responses.  

The study demonstrated that saccades modulate more widespread brain regions than previously thought and are likely involved in higher-order cognitive processing such as attention and memory. Both film cuts and eye movements have a widespread impact on the brain, and their effects are influenced by introducing new and meaningful information. 

Cited publication

Nentwich, M., Leszczynski, M., Russ, B.E. et al. Semantic novelty modulates neural responses to visual change across the human brain. Nat Commun 14, 2910 (2023).