Search

Chronic multichannel neural recording has emerged as a powerful technique for studying dynamic brain function. In many experimental paradigms, it is important that the same neurons be recorded from day to day. The objective of this study was to develop methods for tracking the recorded neural population over time through analysis of unit waveforms, principle component clusters and response properties of single units and multiunit clusters. We demonstrate that these techniques can be used to provide a useful measure of unit stability over extended recording periods.

Chronic, multichannel recordings provide a method for reliable detection and determination of long-term dynamic functional connectivity. Using chronically implanted multichannel electrode arrays, we simultaneously recorded 30–70 units in guinea pig auditory cortex in daily recording sessions for implant durations of six months. We examined stimulus response properties and correlation strengths in neuron pairs in four animals. Preliminary results from these `snapshots’ of functional connectivity suggest sparse functional connections among widely distributed neurons. Some of these functional connections were found to persist for several days. These results provide a framework upon which further investigations of functional dynamic connectivity can be developed.

We implanted microelectrode arrays bilaterally into auditory cortex of trained cats in order to assess dynamic cortical reorganization. Cats were trained to listen to a series of tone-pip pairs and respond to the pair that had different frequencies. Over several months of training, a gradual decrease (−4.2×10−4 Weber Fractions/training day) in the frequency discrimination threshold occurred (p