The external world is represented in the brain as spatiotemporal patterns of electrical activity. Sensory signals,
such as light, sound, and touch, are transduced at the periphery and subsequently transformed by various stages
of neural circuitry, resulting in increasingly abstract representations through the sensory pathways of the brain. It
is these representations that ultimately give rise to sensory perception. Deciphering the messages conveyed in
the representations is often referred to as "reading the neural code." True understanding of the neural code
requires knowledge of not only the representation of the external world at one particular stage of the neural
pathway, but ultimately how sensory information is communicated from the periphery to successive downstream
brain structures. Our laboratory has focused on various challenges posed by this problem, some of which I will
discuss. In contrast, prosthetic devices designed to augment or replace sensory function rely on the principle of
artificially activating neural circuits to induce a desired perception, which we might refer to as "writing the neural
code." This requires not only significant challenges in biomaterials and interfaces, but also in knowing precisely
what to tell the brain to do. Our laboratory has begun some preliminary work in this direction that I will discuss.
Taken together, an understanding of these complexities and others is critical for understanding how information
about the outside world is acquired and communicated to downstream brain structures, in relating spatiotemporal
patterns of neural activity to sensory perception, and for the development of engineered devices for replacing or
augmenting sensory function lost to trauma or disease.