Sensory reception is essential for detecting prey and avoiding predators, for detecting and selecting mates, and for communicating. In these lectures, Dr. Hudspeth and Dr. Nathans will explore the varieties of sensory experience and the underlying biological mechanisms. The first lecture will introduce the strategies shared by most sensory systems and will demonstrate how these strategies have emerged to make sensory systems swift, sensitive, and nearly noise-free. Human vision begins when an image is detected by the light-sensitive cells of the retina at the back of the eye. Light absorption by these photoreceptors triggers a cascade of chemical reactions, leading to an electrical signal this is passed to other layers of the retina for analysis.
Hearing involves the detection of mechanical inputs, the vibrations produced by sound waves.
By transducing mechanical stimuli directly, without the intervention of chemical reactions, the receptive hair cells of the internal ear achieve the remarkable speed of operation that underlies our responsiveness to high-frequency sounds. The final lecture will discuss the neural pathways that mediate the processing of sensory inputs. The patterns of neuronal activity in the visual, auditory, and somatosensory systems suggest that the central nervous system uses common algorithms for processing various sorts of sensory information. In bacteria and other single-celled organisms, light touch and chemical substances can influence the speed and direction of movement. The initial step in the response to any stimulus is sensory transduction, the translation of the stimulus into an intracellular signal.