What happens to the temporary scaffolding cells that help build the brain during development, and could their remnants explain cognitive disorders? Neuroscientist Zoltan Molnar from the University of Oxford returns to the Convergent Science Network podcast after 11 years to discuss how transient cell populations in the subplate regulate cortical circuit formation, and why the prolonged timeline of human brain development may be both a vulnerability and an evolutionary advantage. Subscribe for more from the Convergent Science Network podcast series. Zoltan Molnar, a leading expert on cortical development and subplate neurobiology at the University of Oxford, joins Paul Verschure and Tony Prescott at the BCBT school for a follow-up conversation more than a decade after his first CSN interview. The discussion centers on how the brain's prolonged developmental timeline, particularly in humans, creates extended periods where transient circuits coexist with maturing adult connectivity. Molnar explains that human brain development is remarkably prolonged compared to other mammals. Thalamic projections arrive near the cortex early but accumulate in the subplate for months before making their final connections, a process that takes hours in mice but months in humans. This raises fundamental questions about whether developmental time scales with life expectancy and whether a meta-level controller ensures stability during this extended self-organizing process. The conversation explores the subplate as a transient scaffolding layer: the earliest-generated neurons that receive the first synapses, guide thalamocortical connectivity, and then partially disappear through programmed cell death. Molnar argues that similar transient populations exist elsewhere, particularly in the thalamic reticular nucleus, which may serve as the subplate equivalent for corticothalamic projections. The discussion addresses an ongoing scientific debate about whether subplate cells truly disappear or persist into adulthood. Molnar presents evidence for preferential cell death between postnatal days 2-8 in rodents, while acknowledging that subpopulations born at different times may have different fates. The remaining interstitial cells appear to regulate local arousal, attention, and sleep states in the adult brain. The broader implication is that abnormal development of these transient circuits may underlie cognitive disorders, connecting developmental neurobiology directly to clinical neuroscience. Part of the Convergent Science Network podcast series from the BCBT School.