Neurobiological Correlates of Mental Imagery to Sensory Perception

Neurobiological Correlates of Mental Imagery to Sensory Perception

Understanding the brain's function in the human body involves examining how inputs are processed and outputs are generated. On a reductionist, neuronal level it is often difficult to conceive how such processes lead to our experience of the world. While sensory perception and motor output can be directly traced along neuronal pathways, science is still struggling to understand the roots of such internal, intangible processes as thinking, memory, I function and ultimately consciousness. It seems possible that these phenomena emerge through the complex integration of lower level processes, but our knowledge is far from being able to comprehend how this might occur.

Until recently, these abstract concepts have been the domain of cognitive psychology and philosophy. Relying on introspection to get at the nature of our experience, the early philosopher's excursions into these realms were necessarily highly subjective and were not concerned with biological or anatomical functionality. With the popularity of behaviorism in the early 1900's, mainstream psychologists avoided reference to such issues. The development of cognitive psychology pushed internal processes to the forefront, and examined them by utilizing behavioral indicators to theorize about the underlying concepts of thinking and consciousness (1).

However, only in the last two decades have psychologists been able to take advantage of technology which reveals the activity of the brain during cognitive tasks. This new approach, dubbed cognitive neuroscience, has attempted to corroborate theories on mental processes with empirical evidence of brain activity (2) . These scientists are now beginning to understand how the brain is responsible for such processes.

One of the prime candidates for neurobiological inspection is the phenomenon of mental imagery. Introspectively, this ability seems closely tied to perception, of which we have a firm biological grasp. Furthermore, mental imagery has implications regarding memory, thought, reasoning and emotion, which often seem intrinsically tied to imagery. Mental imagery is an interesting phenomenon because it blurs the line between inputs and outputs. On the one hand, imagery can be considered an input such as vision because we can observe elements of shape, size and color. On the other hand, we can actively manipulate mental imagery, which resembles a behavioral output of sorts. Either way, mental imagery is generated internally without any necessary external prime. Psychologists and philosophers have long pondered our ability to obtain, examine and manipulate a picture in our head without utilizing actual sensory input.