Self Comes to Mind

evolutionary biology and neurobiology. It requires us to consider early living organisms first, then gradually move across evolutionary history toward current organisms. It requires us to note incremental modifications of nervous systems and link them to the incremental emergence of, respectively, behavior, mind, and self. It also requires an internal working hypothesis: that mental events are equivalent to certain kinds of brain events. Of course, mental activity is caused by the brain events that antecede it, but at the end of the day, the mental events correspond to certain states of brain circuits. In other words, some neural patterns are simultaneously mental images. When some other neural patterns generate a rich enough self process subject, the images can become known . But if no self is generated, the images still are , although no one, inside or outside the organism, knows of their existence. Subjectivity is not required for mental states to exist, only for them to be privately known.
    In brief, the fourth perspective asks us to construct, simultaneously, with the help of available facts, a view from the past, and from within, literally an imagined view of a brain caught in the state of containing a conscious mind. To be sure, this is a conjectural, hypothetical view. There are facts to support parts of this imaginarium, but it is in the nature of the “mind-self-body-brain problem” that we must live for quite a while with theoretical approximations rather than complete explanations.
    It might be tempting to regard the hypothesized equivalence of mind events to certain brain events as a crude reduction of the complex to the simple. This would be a false impression, however, given that neurobiological phenomena are immensely complex to begin with, anything but simple. The explanatory reductions involved here are not from the complex to the simple but rather from the extremely complex to the slightly less so. Although this book is not about the biology of simple organisms, the facts to which I allude in Chapter 2 make it clear that the lives of cells occur in extraordinary complex universes that formally resemble, in many ways, our elaborate human universe. The world and behavior of a single-cell organism such as the paramecium are a wonder to behold, far closer to who we are than meets the eye.
    It is also tempting to interpret the proposed brain-mind equivalence as a neglect of the role of culture in the generation of the mind or as a downgrading of the role of individual effort in the shaping of the mind. Nothing could be farther from my formulation, as will become clear.
    Using the fourth perspective, I can now rephrase some of the statements made earlier in a way that takes into account facts from evolutionary biology and includes the brain: countless creatures for millions of years have had active minds happening in their brains , but only after those brains developed a protagonist capable of bearing witness did consciousness begin, in the strict sense, and only after those brains developed language did it become widely known that minds did exist. The witness is the something extra that reveals the presence of implicit brain events we call mental. Understanding how the brain produces that something extra, the protagonist we carry around and call self, or me, or I, is an important goal of the neurobiology of consciousness.
The Framework
     
    Before I sketch the framework guiding this book, I need to introduce some basic facts. Organisms make minds out of the activity of special cells known as neurons. Neurons share most of the characteristics of other cells in our body, and yet their operation is distinctive. They are sensitive to changes around them; they are excitable (an interesting property they share with muscle cells). Thanks to a fibrous prolongation known as the axon, and to the end region of the axon known as the synapse, neurons can send signals to other cells—other neurons, muscle cells—often quite far away. Neurons are largely concentrated in a central nervous system (the brain, for short), but they send signals to the organism’s body, as well as to the outside world, and they receive signals from both.
    The number of neurons in each human brain is on the order of billions, and the synaptic contacts that the neurons make among themselves number in the trillions. Neurons are organized in small microscopic circuits, whose combination constitutes progressively larger circuits, which in