Doors of Perception: Through Which Experience Reaches the Brain

Sight

How our brain is able to interpret photons into meaningful information has intrigued philosophers, psychologists and neuroscientists for generations. This problem continues to hold the attention of researchers all over the world.

Hubel and Wiesel propelled a generation of scientists to deconstruct how the brain gives us sight. Former students trained in their labs are now advancing those early insights. Margaret Livingstone studies how facial recognition and processing occurs in the visual cortex, and the ways in which neurons respond to different aspects of visual information. Richard Born also studies the visual cortex of behaving monkeys, and examines how distinct aspects of visual information guide decision making. John Assad studies how sensory information impacts attention and other internal states, like motivation. David Cox is reverse engineering the visual brain using computer modeling in an effort to understand the principles underlying vision.

At a different level of resolution, Joshua Sanes in the Department of Molecular and Cellular Biology and Center for Brain Science, and Connie Cepko in the Department of Genetics at Harvard Medical School ,both study the genes that regulate the development of retinal cells and the precise assembly of the many retinal cells into circuits. Using molecular tools, they are able to examine the contribution of these genes to circuit assembly.

Early pioneers in research about the eye and vision on Brain Tour Edward Tichener and George Wald.

Smell and Taste

Olfactory perception (in the nose) and gustatory perception (in the tongue) go hand in hand. Both systems have specialized cells that capture molecules and interpret these chemical stimuli. The nasal cavity and tongue are studded with chemoreceptors that bind to odorants and tastants. Once bound, these receptors transmit a neural impulse to the brain, thereby initiating sensory processing.

Rachel Wilson uses the fruit fly brain as a model to study how neural computations in the brain influence the integration of sensory information.

Bob Datta studies how the brain processes smells, and extends these studies to understanding how the brain uses olfactory information to execute behavior. He has recently found a novel class of odorant receptors (different from the conventional odorant receptors based on molecular characteristics and the part of the brain that uses them). Intriguingly, these receptors may be specifically tuned to mediating odors that are innately important to the animal, like food preference or aversion.

For more on the olfactory powers, watch this video from the Datta Lab. Or you can take the The Jelly Bean Test that demonstrates the interdependence of smell and taste.

See the 1938 osmoscope and learn about early pioneers in the olfactory system.

Touch

Our ability to feel mechanical sensations and recognize where our bodies are in space profoundly affect us in everyday life, help us maintain our physical safety and mediate our social interactions.

The Ginty Lab studies the somatosensory neurons of the nervous system, and maps how spinal cord circuits process tactile information.

The Woolf Lab has forged breakthroughs in understanding how sensory neurons process pain. They have discovered an important principle in the field of pain, “central sensitization”, which describes the dysfunction in spinal circuits responsible for chronic pain.

Hearing

Last, but not least, an enormous amount of human experience is delivered in the form of sound waves. The Corey Lab is dedicated to elucidating the neurophysiology of hearing. They study auditory hair cells, the primary cells that translate sound waves into neural signals, using both molecular and biophysical approaches to characterize their behavior, and the molecules that initiate signaling to the brain.

The Goodrich Lab applies molecular tools to explore the development of inner ear cells, and how they get wired into functional circuits during development, and affect an animal’s ability to hear and move.

The biology of the inner ear has important implications for hearing, but also for an under-appreciated sense: knowledge of one’s spatial orientation, which helps us to maintain our balance. Studying the mechanics of these cells, therefore, reveals some of the basic principles of how we hear and stay upright.

Early explorations of the auditory system were led by Georg Von Békésy, SS Stevens, Helmholtz and Hermann von Helmholtz.