Studying Consciousness Using Direct Recording from Single Neurons in the Human Brain

Abstract

Consciousness represents a unity of experience derived from limitless possibilities and fierce competition for dominance within our brain. This unity reflects the compromise of an internal representation of the world that shapes our perception of the environment and guides the choices we make in interacting with it. Here we investigate the relationship between the external environment, our internal representation of it, and volition, using direct recording from single neurons in the brains of 12 patients with pharmacologically intractable epilepsy. In two novel experiments we pit the world within against the world outside, and separate the decision making processes within the brain from the sensation of volition. We show that subjects are capable of overriding external sensory input with internal imagery, and can directly control the firing rate of individual neurons in the medial temporal lobe. Additionally, we show that decision can be predicted before the conscious perception of volition, but that feeding this decision forward and bypassing volition leads to a gradual loss of predictive ability as the neurons alter their activity in response. We propose a working definition for consciousness based on these results, suggesting that consciousness involves our memory and experience of events and ties these together in a working narrative.