Ehud Kaplan

Research

Specific Clinical/Research Interests: Neurophysiology; visual neuroscience

Current Students: Chris Kananau

Research Personnel: Youping Xiao, Ph.D.; Alex Casti, Ph.D., Yunguo Yu, MD- Ph.D.

Information Processing in the Nervous (Visual) System
We explore information processing in the nervous system, and use the visual system as a convenient model. We employ systems analysis, borrowed from communication engineering, as the conceptual and methodological framework. We have developed sophisticated techniques for stimulation of the visual system, and for the analysis of neuronal responses to these stimuli. We use single unit recordings and optical imaging of neuronal activity. We also record simultaneously the input and output of neurons in the visual thalamic nucleus, the lateral geniculate nucleus (LGN), in order to learn how information transmission from the retina to the visual cortex through the LGN is controlled. Applied mathematics and computers are used extensively for stimulation, analysis and modeling of the systems under study.

Currently we are investigating the properties of visual neurons in the retina, LGN and visual cortex of monkeys and cats, with an emphasis on the temporal, spatial and chromatic selectivities of these cells, and on the nature, source and function of the variability (noise) of neuronal responses. Since perception and behavior involve the coordinated activity of many interacting neurons, we also image the spatio-temporal distribution of activity in neuronal ensembles in the visual cortex. In addition, the experimental approaches are augmented by computational modeling of LGN neurons and cortical circuits.

Optical imaging of ocular dominance columns in monkey visual cortex. Dark bands respond to left eye stimulation; light bands respond to right eye stimulation
(From E. O'Brien's thesis)

Left: A map of the primate cortical region that process chromatic information (red/green in this case).
Right: Autocorrelation of the image on the left, showing the spatial scale of the chromatic system
(From D. Orbach's thesis).

Optical signals recorded from the cat visual cortex closely reflect the firing rate of single cortical neurons
(From E. O'Brien's thesis).

For the thrilling start of a nice little movie, click here.
For part 2 of the nice little movie, click here.
For the next portion of the nice little movie, click here.
For the exciting conclusion of the nice little movie, click here.

Visit Dr. Ehud Kaplan's Visual and Computational Neuroscience for more information.