Human cognitive neuroscience seminar

Speaker: Fahd Yazin (University of Edinburgh)

Title: Fragmentation & Multithreading of Experience in the Default-Mode Network

Abstract: Life is as predictable as our internal models we map the world onto. Moreover, our models' predictions constantly guide and constrain our experience, in ways we are usually unaware of.

How our conscious experience emerge from our predictions is an open question in neuroscience and philosophy. Here we show that during naturalistic viewing of a movie in a large cohort, our conscious experience materialize as a fragmented process from the prefrontal cortex (PFC) in a tripartite manner, before getting unified and integrated within the parietal zones. Moreover this integration operates in a way that implements Multithreading of experiences across models in a parallel, distributed manner. Specifically, domain-specific model representations in the PFC are integrated into the parietal sectors whenever sensory data defies one's ongoing predictions.

Individuals with different models had dissimilar experiences, despite seeing the exact same sensory information, owing to their contrasting predictions, which altered global neural representations across many regions in the cortex, effectively reshaping the shared experience. Critically, the Fragmentation was replicated in a different cohort, watching a different content, through a different modality (story listening), suggesting humans utilize a single, abstract predictive mechanism for vision and language models.

Overall these results suggest conscious experience may emerge compositionally from hierarchical, modular architectures requiring both prefrontal generation and parietal integration, and that top-down predictions also arise from parallelized streams in the PFC, mirroring bottom-up, dual stream sensory pathways.