Submitted on February 2, 2007
Accepted on February 27, 2007
Precise alignment of micro-machined electrode arrays with V1 functional maps
Ian M Nauhaus1* and Dario L. Ringach2
1 Biomedical Engineering, University of California, Los Angeles, Los Angeles, California, United States
2 Departments of Neurobiology & Psychology, UCLA, Los Angeles, California, United States
* To whom correspondence should be addressed. E-mail: inauhaus{at}ucla.edu.
Recent theoretical models of primary visual cortex predict a relationship between receptive field properties and the location of the neuron within the orientation maps. Testing these predictions requires the development of new methods that allow the recording of single units at various locations across the orientation map. Here we present a novel technique for the precise alignment of functional maps and array recordings. Our strategy consists of first measuring the orientation maps in V1 using intrinsic optical imaging. A micro-machined electrode array is subsequently implanted in the same patch of cortex for electrophysiological recordings, including the measurement of orientation tuning curves. The location of the array within the map is then obtained by finding the position that maximizes the agreement between the preferred orientations measured electrically and optically. Experimental results of the alignment procedure from two implementations in monkey V1 are presented. The estimated accuracy of the procedure is evaluated using computer simulations. The methodology should prove useful in studying how signals from the local neighborhood of a neuron, thought to provide a dominant feedback signal, shape the receptive field properties in V1.
