To address this question, Zador and postdoctoral fellow Hysell Oviedo compared neuronal activity in mouse brain slices that were cut to preserve the connectivity along the tonotopic axis vs. activity in slices that were cut perpendicular to it.
To precisely stimulate a single neuron within a slice and record from it, Oviedo and Zador, working in collaboration with former CSHL scientists Karel Svoboda and Ingrid Bureau, used a powerful tool called laser-scanning photostimulation. This method allows the construction of a detailed, high-resolution picture that reveals the position, strength and the number of inputs converging on a single neuron within a slice.
"If you did this experiment in the visual cortex, you would see that the connectivity is the same regardless of which way you cut the slice," explains Oviedo. "But in our experiments in the auditory cortex slices, we found that there was a qualitative difference in the connectivity between slices cut along the tonotopic axis vs. those cut perpendicular to it."
There was an even more striking divergence from the visual cortexand presumably the other cortical regions. As demonstrated by a Nobel Prize-winning discovery in 1962, in the visual cortex, the neurons that share the same input source (or respond to the same signal) are organized into columns. As Oviedo puts it, "all neurons within a column in the vertical cortex are tuned to the same position in space and are more likely to communicate with other neurons from wi
|Contact: Hema Bashyam|
Cold Spring Harbor Laboratory