Hierarchies of description enable understanding of cognitive phenomena in terms of neuron activity

Abstract

One objective of neuroscience is to understand a wide range of specific cognitive processes in terms of neuron activity. The huge amount of observational data about the brain makes achieving this objective challenging. Different models on different levels of detail provide some insight, but the relationship between models on different levels is not clear. Complex computing systems with trillions of components like transistors are fully understood in the sense that system features can be precisely related to transistor activity. Such understanding could not involve a designer simultaneously thinking about the ongoing activity of all the components active in the course of carrying out some system feature. Brain modeling approaches like dynamical systems are inadequate to support understanding of computing systems, because their use relies on approximations like treating all components as more or less identical. Understanding computing systems needs a much more sophisticated use of approximation, involving creation of hierarchies of description in which the higher levels are more approximate, with effective translation between different levels in the hierarchy made possible by using the same general types of information processes on every level. These types are instruction and data read/write. There are no direct resemblances between computers and brains, but natural selection pressures have resulted in brain resources being organized into modular hierarchies and in the existence of two general types of information processes called condition definition/detection and behavioral recommendation. As a result, it is possible to create hierarchies of description linking cognitive phenomena to neuron activity, analogous with but qualitatively different from the hierarchies of description used to understand computing systems. An intuitively satisfying understanding of cognitive processes in terms of more detailed brain activity is then possible.

Accounting for behavioral deficits associated with damage in terms of cortical and subcortical information processes

“…The existence of the architecture and the two general types of information processes makes it possible to create hierarchies of description that enable understanding of cognitive phenomena in terms of brain anatomy and physiology [9]. A cognitive phenomenon can be described end to end in terms of the interactions between the highest-level modules.…”

“…Although there are no resemblances between computing systems and brains, this approach is analogous to the way in which the designs of complex electronic systems are understood [8,9]. Hierarchies of description make it possible to understand system features in terms of transistor operations, with mapping between different levels of description made possible by the use of just two general types of information process on every level, in the case of computers these two types are data read/write and instruction.…”

“…In this paper, descriptions of these defi cits will be developed at the higher levels, with some general indications of how to map to more accurate detailed levels. Coward [9] provides a more detailed description of how the mapping process works for one type of cognitive process.…”

“…Computing systems with trillions of components like transistors are understood in the sense that they can be designed and modifi ed. Although there are no resemblances between brains and computing systems, the way the computing system design information is organized to make understanding possible has some critical lessons for how neuroscience information can be organized to make understanding of cognitive processes possible [7][8][9]. Brains process information derived from the environment, the state of the body, and the internal state of the brain itself.…”

“…In the brain, some high-level anatomical modules exist that specialize mainly in just one of the information processing types: the basal ganglia specialize in behavioral recommendations and the cortex specializes in condition defi ne/detections. As in the case of computing systems, the organization of information processing resources into a modular hierarchy and the limitations of information processes to two general types make it possible to create hierarchies of description linking cognitive phenomena with, ultimately, neuron activity [9]. High-level descriptions of cognitive processes in terms of major anatomical modules are approximate but have a low enough information content that they can be fully understood.…”