Peter Lennie

Functional Organization of Vision

My work sits at the interface between visual perception and visual physiology. All my research is connected by the idea that visual perception can be explained in terms of underlying neural mechanisms. The work involves both perceptual experiments to explore performance, and physiological ones to record the activity of single neurons, the aim being, where possible, to link observations in the two domains.

My recent work has focused on three problems: mechanisms of color vision, the functional organization of visual cortex, and the how the visual system combines information from the two eyes.

Mechanisms of Color Vision

The organization of the early stages of color vision has been generally well-understood for a long time, but the manner in which post-receptoral mechanisms combine cone signals to form color-opponent channels is still not clear. Through simulations and experimental studies, my collaborators and I are exploring how color-opponent receptive fields are formed in the retina and in cortex, and why they might have the properties they do. One problem we are studying is the tradeoff between spatial selectivity and color selectivity within a receptive field. Cones of different classes are arranged randomly in the retinal mosaic (Roorda et al, 2001), so a cortical neuron with a receptive field in or near the fovea can control the retinal positions from which its inputs arise, or the chromatic signatures of the inputs, but not both. The difficulty of concurrently satisfying chromatic and spatial constraints in assembling a receptive field is magnified when a neuron is binocularly driven. Jon Peirce, Sam Solomon and John Krauskopf and I are currently investigating how neurons in V1 and V2 deal with this, by exploring the precision with which the chromatic and spatial properties of receptive fields are matched in the two eyes.

Cortical Organization

Binocular Combination of Visual Signals

Jason Forte, Jamie Kraft, Jonathan Peirce, John Krauskopf and I have explored the mechanisms of binocular single vision, through physiological experiments to understand the rules by which binocular neurons combine signals from the two eyes, and through psychophysical experiments to understand how stable binocular percepts are maintained when neither eye's image contains any component shared by the other. Such situations can arise naturally when objects are viewed through intermittent occluders (e.g. picket fences). Our physiological work has revealed both early and late nonlinearities in the pathways to binocular combination, and these can give rise to a range of distinctive behaviors such as binocular enhancement and binocular attenuation evident in perception. Our perceptual studies (Forte et al., 2002) have revealed the existence of high-level integration processes that can piece together into a coherent whole the sets of image fragments seen by each eye alone.

E-mail: pl@cns.nyu.edu

Some Recent Publications [Selected earlier publications]

• Webb BS, Dhruv NT, Solomon JA, Tailby CT, Lennie P (2005) Early and late mechanisms of surround suppression in striate cortex of macaque. Journal of Neuroscience 25:11666-11675.[PDF (752k)]
• Lennie, P., & Movshon, J.A. (2005). Coding of color and form in the geniculostriate visual pathway. Journal of the Optical Society of America A, 22, 2013-2033. [PDF (776k)]
• Solomon, S.G., & Lennie, P. (2005). Chromatic gain controls in visual cortical neurons. Journal of Neuroscience, 25, 4779-4792. [PDF (1340k)]
• Solomon, S.G., Peirce, J.W., Dhruv, N.T., & Lennie, P. (2004). Profound contrast adaptation early in the visual pathway. Neuron, 42, 155-162. [PDF (158k)]
• Solomon, S.G., Peirce, J.W., & Lennie, P. (2004). The impact of suppressive surrounds on chromatic properties of cortical neurons. Journal of Neuroscience, 24, 148-160. [PDF (458k)]
• Müller, J.R., Metha, A.B., Krauskopf, J., & Lennie, P. (2003). Local signals from beyond the receptive fields of striate cortical neurons. Journal of Neurophysiology, 90 (2), 822-831. [PDF (216k)]
• Lennie, P. The cost of cortical computation. Current Biology 13: 493-497, 2003. [PDF (148k)]
• Forte, J., Peirce, J.W., Kraft, J.M., Krauskopf, J., & Lennie, P. (2002). Residual eye-movements in macaque and their effects on visual responses of neurons. Visual Neuroscience, 19 (1), 31-38. [PDF (964k)]
• Forte, J., Peirce, J., & Lennie, P. (2002). Binocular integration of partially occluded surfaces. Vision Research, 42 (10), 1225-1235. [PDF (580k)]
• Müller, J.R., Metha, A.B., Krauskopf, J., & Lennie, P. (2001). Information conveyed by onset transients in responses of striate cortical neurons. Journal of Neuroscience, 21, 6978-6990. [PDF (394k)]
• Li, A., & Lennie, P. (2001). Importance of color in the segmentation of variegated surfaces. Journal of the Optical Society of America A, 18 (6), 1240-1251. [PDF (262k)]
• Metha, A.B., & Lennie, P. (2001). Transmission of spatial information in S-cone pathways. Visual Neuroscience, 18 (6), 961-972. [PDF (841k)]
• Roorda, A., Metha, A. B., Lennie, P. and Williams, D. R. (2001). Packing arrangement of the three cone classes in primate retina. Vision Research, 41, 1291-1306. [PDF (1195k)]
• Lennie, P. (2000). Color vision: putting it together. Current Biology, 10, R589-R591. [PDF (75k)]
• McMahon, M. J., Lankheet, M. J. M., Lennie, P. and Williams, D. (2000). Fine structure of parvocellular receptive fields in the primate fovea revealed by laser interferometry. Journal of Neuroscience, 20, 2043-2053. [PDF (364k)]
• Müller, J. R., Metha, A. B., Krauskopf, J. and Lennie, P. (1999). Rapid adaptation in visual cortex to the structure of images. Science, 285, 1405-1408. [PDF (110k)]