Internally generated representations (of things like events or facts not currently present) were framed by George Dragoi, MD, PhD, as a shared substrate for memory, planning, imagining, dreaming, and inference, with the hippocampus critically involved in both humans and rodents. When abnormal, these representations may take the form of hallucinations and delusions in disorders like schizophrenia. Dragoi shared these insights at the Precision Therapeutics in Schizophrenia symposium at the Fralin Biomedical Research Institute.
Neuronal activity is organized like a generative grammar, Dragoi proposed. Beyond single-neuron activity, short sequential motifs termed tuplets—2 to 4 neurons that fired in the same order much more often than chance—served as modules, analogous to words, for building longer sequences.1 According to Dragoi, “there are extended sequences that are made to represent new information, new experiences, but they are based on these building blocks which are then later modified by synaptic plasticity to then be consolidated and form memories of events experienced.”