Authors :
Presenting Author: Hongtao Ma, PhD – Weill Cornell Medicine
Jing Li, MD, PhD – Department of Neurology – The First Hospital of Jilin University; James Niemeyer, PhD – Neurological Surgery – Weill Cornell Medicine; Theodore Schwartz, MD – Neurological Surgery – Weill Cornell Medicine; Fan Yang, MD, PhD – Department of Neurology – The First Hospital of Jilin University
Rationale:
The imaging of hemodynamic responses to interictal spikes represents a potentially useful mapping technique in the presurgical evaluation of patients with intractable epilepsy. A detailed understanding of the hemodynamic response function is required for correct interpretation of these signals. However, previous data on interictal neurovascular coupling have been mostly obtained from animals under anesthesia, which can have a profound effect on neurovascular coupling. Therefore, data acquired in awake animals is critical.
Methods:
We used simultaneous mesoscale optical imaging of excitatory neuronal and hemodynamic changes during bicuculline-induced interictal events in both isoflurane-anesthetized and awake mice.
Results:
We found that isoflurane had little impact on the calcium signal but dramatically blunted the amplitude and latency of the hemodynamic response, although not its area of spread. Whether awake or anesthetized, the cerebral blood volume change, reflected in total hemoglobin, provided the best spatial estimation of excitatory neuronal activity. Targeted silencing of the thalamus in awake mice failed to recapitulate the impact of anesthesia on hemodynamic responses suggesting that the thalamocortical loop was not the key structure through which isoflurane impacts interictal neurovascular coupling.
Conclusions:
The blood volume increase associated with interictal spikes represents a promising mapping signal in the awake, unanesthetized state.
Funding: None