Multi-electrode recording is one approach we are using to investigate the role of neuronal activity in visual cortical development. Multi-electrode recording methods are utilized to examine the correlational structure of spontaneous activity within different stages of the developing visual pathway including the lateral geniculate nucleus (LGN) and cortex. We are analyzing the relationship of these activity patterns to the emergence of visual system functional organization such as eye-specific and ON/OFF LGN layers and cortical orientation/ocular dominance columns. Methods are also being developed to manipulate patterns of correlated neuronal activity within the developing visual pathway. This is being accomplished through chronic neural electrical stimulation or by utilizing miniature head mounted visual displays and computer generated imagery to manipulate the correlational structure of the animalÕs visual experience. We are investigating molecular mechanisms of visual cortical development utilizing gene transfection techniques to alter expression patterns of neurotrophins and other molecules in the developing cortex. In vitro brain slice methods are being used to study the effects of these manipulations upon local cortical circuits.

My lab is also utilizing optical and multi-electrode recording methods to study adult and developing cortical functional architecture and circuitry. Questions we are addressing include 1) the development and organization of multiple cortical maps, 2) spatial and temporal population codes of visual stimuli in mature and developing cortex, 3) contextual modulation of population and single cell responses, and 4) plasticity of population and single cell responses during visual conditioning/learning. We are using these experimental results to construct computational models of network interactions across single and multiple visual areas, and investigate their development and role in visual processing tasks such as pattern/object segmentation and discrimination. 

Weliky, M., Katz L.C. (1994) 

Functional mapping of horizontal connections in developing ferret visual cortex: experiments and modeling. J. Neuroscience 14: 7291-7305. 

Weliky, M., Kandler, K., Fitzpatrick, D., Katz, L.C. (1995) 

Patterns of excitation and inhibition evoked by horizontal connections share a common relationship to orientation columns. Neuron 15: 541-552. 

Weliky, M., Bosking, W., Fitzpatrick, D. (1996) 

A systematic map of direction preference in primary visual cortex. Nature 379: 725-728. 

Weliky, M., Katz, L.C. (1997) 

Disruption of orientation tuning in visual cortex by artificially correlated neuronal activity. Nature 386: 680-685.