Memory, Identity & Continuity

Christof Koch argues that materialism has yet to solve the hard problem, and even with major advances in neuroscience, scientists have yet to explain how subjective experience arises from physical brain processes. The two dominant physicalist theories, Integrated Information Theory and Global Neuronal Workspace Theory, were tested head-to-head in the largest adversarial collaboration in consciousness science history, and neither theory's predictions were fully confirmed. This directly challenges substrate-neutral emulation assumptions central to the transfer goal.

Google Research, HHMI Janelia and collaborators published a complete map of the male fruit fly's brain and central nervous system, creating the largest brain map to date. The connectome reveals that visual processing extends deep into the brain engaging more than half of neuron types, and maps the complete taste system from taste neurons across the body to motor neurons that drive feeding. This represents the first whole-organism nervous system connectome and demonstrates the feasibility of mapping complete neural architectures, though functional emulation remains absent.

C. elegans, a 1-millimeter transparent worm, offers a unique opportunity as the complete wiring diagram of the worm is well established, yet scientists have been unsuccessful in emulating its brain activity in a computer. This exposes the structure-to-function gap: connectomes are necessary but not sufficient for emulation, validating the program's open problem that reading synaptic weights and molecular state, not only structure, is the critical unsolved challenge.

MIT researchers are actively planning experiments using transcranial focused ultrasound that will begin with stimulation of the visual cortex and later move to higher-level regions in the frontal cortex to identify the neural substrate of conscious perception. The method offers non-invasive causal intervention to test which brain regions are necessary for consciousness, not merely correlated with it, addressing a core validation problem for any transfer protocol.

Optogenetic studies have been conducted mainly on rodents and non-human primates with only isolated clinical cases in humans; rodent memory can now be manipulated via optogenetics to treat post-traumatic memories, retrieve spatial memory, and even create false memories. Personal identity has been proposed as a neuroright by the Neurorights Foundation. The paper highlights that memory modification technologies force the field to operationalize what counts as identity-preserving intervention.

A new platform called Connectome-seq assigns each neuron a unique RNA barcode; specialized proteins carry these barcodes from the neuron's main body to the synapse, the point where two neurons meet; researchers then isolate these synapses and use high-throughput sequencing to read which barcode pairs are found together, revealing which neurons are directly connected and allowing scientists to map networks on a large scale. This sequencing-based method offers a scalable alternative to electron microscopy for synapse-level mapping.