Broadband synergy versus oscillatory redundancy in the visual cortex
The cortex generates diverse neural dynamics, ranging from broadband fluctuations to narrowband oscillations in specific frequency bands. Here, we investigated whether broadband and oscillatory dynamics play different roles in the encoding and transmission of synergistic and redundant information. We used information-theoretical measures to dissociate neural signals sharing common information (i.e., redundancy) from signals encoding complementary information (i.e., synergy). We analyzed electrocorticography (ECoG) and local field potentials (LFP) in the visual cortex of human and non-human primates (macaque) to investigate to what extent broadband signals (BB) and narrowband gamma (NBG) oscillations conveyed synergistic or redundant information about images. In both species, the information conveyed by BB signals was highly synergistic within and between visual areas. By contrast, the information carried by NBG was primarily redundant within and between the same visual areas. Finally, the information conveyed by BB signals emerged early after stimulus onset, while NBG sustained information at later time points. These results suggest that broadband activity encodes information synergistically while gamma-band oscillatory activity encodes information redundantly in the visual cortex.