|The Brain is Wider than the Sky - a Neuroscientific View of Consciousness
14 September 2006
Type/Items(s): I New Discoveries defining Complexity, Scientific Sessions
Submitted by: Tatjana Schwabe (ICVolunteers)
Contributors: Kate Howell (ICVolunteers), Randy Schmieder (MCART)
|While the Greek philosophers and Renaissance men made no distinction between studying natural phenomena, philosophy or creating art, with the advent of the scientific revolution, dualism was introduced and a rift was perceived between natural sciences and humanities. The human mind was removed from the study of modern science and became a subject of philosophical discourse.
Only with the work of scientists such as William James did natural sciences try to study the human mind and consciousness.
Today, several questions can be posed, such as how is the brain put together? How does it perform its fundamental operations? What are the bases of perception and how does memory work? What is consciousness?
Modern scientists are trained in the scientific method and aim to reduce complex problems to a testable model system. While originating the idea that parts of the mind may be linked to function, phrenology itself is now discredited as pseudioscience.
|The precept is however, that it is possible to account for consciousness by analysing brain function. Professor Gerald M. Edelman, Nobel Laureate, The Neurosciences Institute, San Diego, California, USA, argues that this is indeed the case and presented several experiments showing how consciousness can become a scientific subject. Indeed, the day may come when neuroscience is advanced enough to construct a conscious artefact and epistemology, the theory of knowledge, will become a truly experimental science.
The first keynote lecture to introduce the concept of complexity was given by Prof. Gerard Edelman. While Prof. Edelman is a medical doctor by training, his scientific research has focused on numerous topics, from protein structure (he was awarded the Nobel prize for Physiology or Medicine in 1972 for his studies on the structure and function of antibodies) to cell-cell interactions, cell growth and development and neuroscience. As his research subjects became more and more complex, moving from single protein molecules to cells to organs and organism, the approach to study them had to move from a reductionist approach to a more complex and encompassing philosophy.
Modern scientists are trained in the scientific method and aim to reduce complex problems to a testable model system. A model of the brain begins with examining the cellular structure and interactions of neurons as the functioning parts. However, as more information fed in from other fields like genetics and behavioural studies, this reductionist tendency resulted in a structural crisis of neuroscientific studies.
Methodological advances allowed for experiments which investigated the problems of connectivity within the brain, but current theories were unable to explain observations such as visual perception phenomena.
Empiric experiments show that perception is context dependent. As an example, a pigeon trained to respond to the visual cue of a silver fish will not respond to the image of a black fish - the two, for us similar marine organisms, are completely distinct entities for the pigeon. Similarly, optical illusions like illusory contours, trick the human mind into seeing geometric shapes that are not really present. Throughout embryogenesis, a repertoire of neural circuits is created in the brain, as encoded by epigenetic variation. Through developmental and experimental selection, these circuits are either reinforced or weakened, in a process called re-entrant mapping. In this way, neural systems evolve in order to incorporate value systems depending on actual experience.
On this basis, Prof. Edelman proposed the Neuronal Group Selection Theory (or Neural Darwinism) to incorporate Darwin's thinking of evolution with the observation of perception being adaptive and context-sensitive. In other words, that the brain is not a computer, and that the brain cannot be studied in isolation from the body and the environment.
Brain-based devices (BBD), are a special, advanced type of robot, which are used to test the hypothesis of neural Darwinism. Although these are perforce a reductionist approach to the human mind, several criteria are applied to keep the model as realistic as possible. BBDs are situated in the real world, they engage in behavioural tasks, and their behaviour is controlled by a simulated nervous system based on the brain's anatomy and dynamics. This behaviour is then modified by a reward and value system.
Analysing the way the BBDs learn from experience and perform their tasks, as well as the "brain" that is formed through this adaptative process, it becomes clear that this is not a replicative, but a dynamic reaction. Re-entrant maps result in different structures, which give the same output (for example the robot reaching a certain spot on the ground after using environmental cues to find it).
The BBD experiments have shown that location has an important consequence for memory, and this is summarised by the Jamesonian Principles of Consciousness. Consciousness is a form of awareness, is it a process, not an object, as it has individual and personal qualities. It is continuous and changing, has intentionality, but the neuronal basis of consciousness has not been established. From an evolutionary perspective, one of the first questions of consciousness is to ask 'what happened last time?', when a prey learns to associate signals of a predator's approach with the vital reaction of fleeing.
Another example of primary consciousness can be found in binocular rivalry. By investigating human responses to complex visual cues such as a grid of contrasting colours, it is possible to scientifically evaluate the ideas of feeling and perception. These experiments support an integrated model of the mind in a larger system of internal and external cues, where feedback and inputs give a conscious state. Different states of the dynamic core hypothesis give different qualia, or subjective feelings. Therefore, consciousness can begin to be explained in neuronal terms, and in the domain of traditional scientific investigation.
Professor Edelman's initiatives in neuroscience particularly the brain and consciousness demonstrate that scientific methodologies can bridge the gap between the study of the philosophy of the mind and investigative science.
Prof. Edelman chose two poems to bracket his presentation and to describe not only the brain but providing one of the bridges between natural science and the arts; with Marianne Moore's The Mind is an Enchanting Thing opening the talk and Emily Dickinson's The brain is wider than the sky concluding it.