An affordable solution for investigating zebra finch intracranial EEG signals v1

The Zebra finch is a well-studied model animal for neural mechanisms of speech, and Electrophysiology is the primary technique for understanding the song system in them. Most of the studies on zebra finches have focused on intracerebral recordings. However, these methods are not readily available and expensive. Recently, different open-source hardware for acquiring EEG signals has been developed. It's unclear if these solutions are suitable zebra finches as they haven't been evaluated yet. Electrocorticography signals, which have been overlooked in avian electrophysiology, can be helpful in studying bird songs. They can provide a preliminary guide for more in-depth inquiries and also aid in understanding the global behavior of the bird’s brain, as opposed to the more common localized approach. We provide a detailed protocol for acquiring ECOG data from zebra finches with an open-source device (open BCI). We implemented stainless steel electrodes on the brain's surface and recorded the brain signals from two recording sites. To validate our method, we ran two different experiments. In the first experiment, we recorded neural activity under different concentrations of isoflurane and extracted the burst suppression rate (BSR) to measure anesthesia depth. In the second experiment, we head-fixed the birds and presented them with different auditory stimuli to evaluate event-related potential. Results showed a significant increase in the BRS by increasing the anesthesia depth. And significant ERP response to auditory stimuli. These findings indicate that by our methodology, we can successfully collect ECOG signals from awake and anesthetized birds.