Podcast with Viktor Lamme on consciousness and recurrent processing

Can neuroscience tell us what consciousness really is , even when introspection and behavior fall short? Viktor Lamme argues that recurrent neural processing, not global workspace activation, is the fundamental ingredient of conscious experience. Subscribe for more from the Convergent Science Network podcast series. Viktor Lamme opens with a challenge to the dominant paradigm in consciousness research: if we cannot reliably know what we are conscious of at any given moment, then searching for neural correlates of consciousness is fundamentally misguided. Instead, he proposes building a definition of consciousness from neuroscientific evidence itself , using neural arguments rather than behavioral reports to determine when and where conscious experience occurs. At the core of his theory are four stages of cortical processing. Stages one and two involve feedforward activation, shallow or deep, that can reach prefrontal cortex and trigger cognitive functions like attention and inhibitory control, yet remain entirely unconscious. Stages three and four involve recurrent or reentrant processing, where higher areas feed back into lower areas. Lamme's central claim is that recurrent processing is both necessary and sufficient for consciousness. Even localized recurrence between early visual areas produces a conscious percept, albeit a primitive one, while widespread recurrence incorporating frontoparietal networks adds reportability and cognitive access without adding consciousness itself. This directly challenges global workspace theory, which holds that prefrontal-parietal broadcasting is essential for conscious experience. Lamme argues that this conflates consciousness with attention, cognitive control, and reportability. He points to evidence that prefrontal activation can occur without consciousness and that consciousness can occur without prefrontal involvement. The distinction matters clinically and scientifically: if consciousness requires only local recurrence, then patients and experimental subjects may have rich conscious experiences that they simply cannot report. The interview takes a molecular turn when Lamme describes experiments showing that recurrent signals in monkey visual cortex depend on NMDA receptors, while feedforward signals rely on AMPA receptors. This dissociation suggests that conscious processing may be uniquely linked to synaptic plasticity , raising the provocative prediction that there is no such thing as truly unconscious learning. Every instance of learning in the literature that Lamme has examined involves conditions where local recurrent processing could plausibly be occurring, even if global reportability is absent.