The Brain from Inside Out

by György Buzsáki

More complex brains are organized in a “multiple loop” pattern. These parallel loops, each with increasing levels of complexity of wiring and temporal dynamics, are inserted between the output and input (middle panel). For example, in mammals, the most direct circuit between sensors and muscle activation is the monosynaptic spinal cord/brainstem connection. More complex loops connecting these same inputs and outputs include the thalamocortical system and bidirectional communication between the neocortex and several subcortical structures. In addition, a side loop of the hippocampal system is dedicated to generate sequential neuronal activity such that content in the thalamocortical loops is organized into orderly trajectories, allowing simultaneous postdiction (memory) and prediction (planning) operations (as elaborated in Chapter 13). Large and small brains share the same main goal: to predict the future consequences of their actions. However, the multiple interacting loops and the hippocampal postdiction-prediction system allow more sophisticated brains to predict action outcomes more effectively at much longer time scales and in more complex environments.