The preferential response of neurons to visual stimuli moving in a particular direction is a feature of the mammalian visual system that is critical for the perception of motion and for guiding oculomotor and reaching behaviors. Direction-selective neurons have been identified in the retina, in subcortical areas that receive retinal input, and in cortical areas known to process visual motion signals. Understanding the circuitry that underlies direction selectivity at these different stages of visual processing is important for understanding how we perceive the motion properties of visual stimuli, and might serve as a general model of how neuronal circuits that encode specific features of stimuli are formed.
An NEI-supported research team using transgenic mice along with sophisticated anatomical and functional imaging systems has discovered a unique genetic marker that identifies a specific class of direction-sensitive cells in the retina. This marker was then used to map the spatial distribution of these neurons, to examine their dendritic fields and synaptic partners, to characterize their physiological response to moving stimuli, and to trace their axonal projections to central nervous system targets. These data provide evidence that direction-selective neurons have a unique molecular signature that dictates the specific connections with other neurons and functional properties related to the motion of visual stimuli.
Public Impact Statement/Significance:
These results are a major new step in understanding the molecular mechanisms that dictate the specific connections that are required within circuits responsible for processing specific types of visual information. This is important not only for understanding normal developmental processes, but also for understanding how to induce the precise connections needed to restore function after retinal injury or in ocular diseases such as glaucoma and optic neuritis.
U.S. National Institutes of Health, National Eye Institute (Optic Nerve Myelination, R01EY011310; Development of Synaptic Specificity in the Mammalian Visual System, R21EY018320; Function of Neural Activity in Developing Retina, R01EY13528)
Huberman, A.D., et al. Genetic Identification of an On-Off Direction-Selective Retinal Ganglion Cell Subtype Reveals Neural Circuitry Underlying Perception of Motion. Neuron. 2009; 62:327-334. PubMed
Last Reviewed: May 2009