Our laboratory is concerned with the neural organization of central visual pathways in the brain. We are interested in how visual information is encoded, transmitted and detected. We seek to determine the neural basis of specific aspects of visual performance. In addition to the consideration of normal visual organization, we are interested in development and plasticity of vision. What is genetically determined and what is shaped by the visual environment?
Our approach is to try to formulate physiologically plausible hypotheses or models whose predictions are subject to experimental verification. We then design and perform experiments that are specifically intended to test the predictions of the hypotheses or models.
Our experimental approaches are neurophysiological and involve extracellular microelectrode recordings from single or multiple neurons. Most of our work concerns striate or extra-striate visual cortex but we also address questions that require recording in the lateral geniculate nucleus. We are now able to record from small groups of cells simultaneously by use of several adjacent electrodes. This allows cross-correlation analysis to be used between different combinations of cell pairs, which provides insights about functional connections between neurons. Conventional and elaborate visual stimulation techniques are used. In this way, a variety of visual parameters can be studied simultaneously. Most of our work is of a quantitative nature and extensive use is made of computers.
Recently, we have developed an interest in the relationship between neural and metabolic activity in the brain. This topic is fundamentally important for the field of functional magnetic resonance imaging (fMRI). fMRI is an exciting and relatively new method for monitoring neural activity non-invasively. It has both basic and clinical applications. The technique infers changes in neural activity through signals dependent on blood flow and oxidative metabolism. To explore this relationship, we have made simultaneous measurements of neural activity and associated levels of tissue oxygenation in co-localized regions of the visual pathway (Thompson, J.K., Peterson, M., Freeman, R.D. (2003) Single Neuron Activity and Tissue Oxygenation in the Cerebral Cortex. Science 299: 1070-1072). We are pursuing this work in current investigations.
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