Introduction

Abstract

In this session, we go beyond molecular and cellular levels to neural levels of the brain. Neural tissues of the brain are essentially highly complex neuronal networks containing an enormous number of neurons and their processes. These elements are not only hard-wired, but they contain flexible elements, i.e., synapses with plasticity. During the past 20 years, four basic types of synaptic plasticity have been uncovered: long-term potentiation, long-term depression, sensitization, and sprouting. With these various types of synaptic plasticity incorporated, a neural tissue assumes self-organizing capabilities that are the basis of memory and learning. A number of neuronal networks are gathered to form large-scale functional systems of the brain, each devoted to recognition, motor control, emotion, wakefulness, sleep, and so on. To investigate this complexity of the brain, numerous new techniques have been introduced during the past 20 years, but certainly we need more. Not only experimental analyses, but also theoretical syntheses have to be promoted, as the essential feature of neuronal networks and systems is information, rather than material. While neurosciences at molecular and cellular levels will provide us with means for operating on the brain and for curing diseases and damage, neurosciences at network and system levels will enable us to mimic artificially the superb information-processing capabilities of the brain, and to open the way to understanding mechanisms of our mental functions. Thence, different aspects of ethics are inherent to neurosciences at these different levels.