[PEER REVIEWED] An affordable solution for investigating zebra finch intracranial EEG signals v3
Milad Yekani, Mohammad-Mahdi Abolghasemi, Shahriar Rezghi Shirsavar, Amirreza Bahramani · 2023
The Zebra finch is a well-studied animal model for investigating the neural mechanisms of speech-vocal learning, and electrophysiology is the primary technique for understanding the song system. Most of the studies on zebra finches have focused on intracerebral recordings. However, these methods are only affordable for a limited number of laboratories. Different open-source hardware for acquiring electroencephalograph (EEG) signals has recently been developed. It is unclear whether these solutions are suitable for zebra finch studies, as they have not yet been evaluated. Electrocorticography signals can provide a preliminary guide for more in-depth inquiries and aid in understanding the global behavior of the bird’s brain, as opposed to the more common localized approach. We provided a detailed protocol for acquiring intracranial electroencephalography (iEEG) data from zebra finches with an open-source device. We implemented stainless steel electrodes on the brain's surface and recorded the brain signals from two recording sites above two auditory-responsive nuclei. To validate our method, we ran two different experiments. In the first experiment, we recorded neural activity under various concentrations of isoflurane and extracted the suppression duration to measure anesthesia depth. In the second experiment, we head-fixed the birds, and under light anesthesia, we presented them with different auditory stimuli to evaluate event-related potential (ERP). Results showed a significant increase in the suppression duration by increasing the anesthesia depth, and it was evident the ERP response to auditory stimuli was different. These findings indicate that we can successfully collect iEEG signals from anesthetized zebra finches using our methodology. These findings pave the way for future studies to use iEEG to investigate bird cognition more affordably.