Research Snapshot: Drs. Kara Johnson and Coralie de Hemptinne

By Michelle Jaffee

portrait of two female researchers
(From left) Drs. Coralie de Hemptinne and Kara A. Johnson

New research by University of Florida neuroscientists found that a brain signal called evoked resonant neural activity, or ERNA, could serve as a potential marker to guide physicians administering deep brain stimulation for Parkinson’s disease patients.

The study, led by Kara A. Johnson, Ph.D., a postdoctoral associate and biomedical engineer, and Coralie de Hemptinne, Ph.D., a neurophysiologist and an assistant professor in UF’s department of neurology, was published today in the journal Brain Communications.

ERNA is a high-frequency oscillatory brain signal that occurs in response to deep brain stimulation, known as DBS. While research at other institutions has illuminated the role of ERNA in the subthalamic nucleus of the brain, the new study is the first to analyze ERNA in the globus pallidus internus area. Those two brain regions are the most common to be targeted with DBS for medication-refractory Parkinson’s disease.

“Our results show that ERNA in response to globus pallidus internus DBS shows promise as a potential marker to determine where the DBS electrodes should be implanted in the brain and to help clinicians identify effective stimulation parameters to improve Parkinson’s disease symptoms,” Johnson said.

graph of neuronal activity
Example recording of evoked resonant neural activity (ERNA) elicited by bursts of high-frequency stimulation delivered from the deep brain stimulation (DBS) electrode in a patient with Parkinson’s disease.

To determine if ERNA is a common feature among different individuals and if the spatial topography of ERNA could be used to evaluate specific anatomical substructures, the research team collected recordings of brain signals of 26 Parkinson’s disease patients during DBS implantation surgery and nine essential tremor patients as the control. During the recordings, electrical stimulation was delivered, and researchers analyzed the neural response to detect ERNA. They then used neuroimaging to uncover the brain regions where ERNA was most likely to occur. Then they determined that ERNA was correlated with postoperative stimulation parameters used for ongoing therapeutic DBS.

Johnson said the goal is to continue to optimize deep brain stimulation to improve quality of life for Parkinson’s patients who are candidates for the treatment.

“Current approaches in DBS require extensive intraoperative testing during surgery to verify that the DBS electrode is optimally placed, as well as several time-consuming clinic visits after surgery to determine effective stimulation parameters,” she said. “Objective electrophysiology markers, such as ERNA, have the potential to expedite the process of intraoperative targeting and to aid clinicians in identifying effective stimulation parameters.”

The next step in this line of research is to investigate mechanisms underlying ERNA and evaluate whether it could be used as a validated, prospective marker to guide DBS in Parkinson’s patients.

Read the paper in Brain Communications.