Mouse Model of Focal Limbic Seizures with Impaired Behavior Associated with Cortical Slow Waves and Reduced Cholinergic Arousal
Abstract number :
3.122
Submission category :
2. Translational Research / 2D. Models
Year :
2021
Submission ID :
1825700
Source :
www.aesnet.org
Presentation date :
12/6/2021 12:00:00 PM
Published date :
Nov 22, 2021, 06:50 AM
Authors :
Shobhit Singla, MD/PhD - Yale University; Lim-Anna Sieu, PhD – Yale University; Abdelrahman Sharafeldin, BS – Yale University; Ganesh Chandrasekaran, BS – Yale University; Marcus Valcarce-Aspegren, MD – Yale University; Ava Niknahad, BS – Yale University; Ivory Fu, student – Yale University; Natnael Doilicho, MD – Yale University; Abhijeet Gummadavelli, MD – Yale University; Cian McCafferty, PhD – University College Cork; Richard Crouse, PhD – Yale University; Quentin Perrenoud, PhD – Yale University; Marina Picciotto, PhD – Yale University; Jessica Cardin, PhD – Yale University; Hal Blumenfeld, MD, PhD – Yale University
Rationale: In humans, temporal lobe epilepsy (TLE) is associated with loss of consciousness and therefore significantly reduced quality of life. Studies in humans have shown that this loss of consciousness is positively correlated with neocortical slow waves on EEG, similar to the non-REM sleep state. Previous work in a rat model of focal limbic seizures suggests a key role for inhibition of subcortical arousal systems, including brainstem and basal forebrain cholinergic neurons. However, a mouse model is much more desirable due to the wealth of genetics tools available to better elucidate underlying circuit and network mechanisms resulting in loss of consciousness.
Methods: Water-restricted mice were trained to lick a spout in response to a sound (0-50kHz noise, 12ms) every 10-15s while head-fixed on a running wheel. Seizure initiation and cortical recordings were performed via implanted bipolar electrodes in the dorsal hippocampus (LFP recording and stimulating) and into the right orbitofrontal cortex (OFC) (LFP recording). Focal limbic seizures were induced by a 2s, 60 Hz hippocampal stimulus. Multiunit activity (MUA) recordings in left OFC were performed via a tungsten electrode. To study cholinergic input to OFC during seizures, a genetically encoded fluorescent acetylcholine indicator (GACh) was expressed in the OFC via viral injection with signals detected via an implanted optic fiber into OFC (fiber photometry).
Results: Focal seizures were of 5-30s duration and repeatable for several weeks (n= 20 animals). Responses to sound and running speed were both decreased during seizures and recovered post-ictally (p < 0.01, n= 20 animals). Similar to TLE in humans responses to sound were sometimes normal, even during seizures. By examining cortical activity and behavioral responses, we showed that behavioral arrest is correlated with amplitude of cortical slow-wave activity, as seen in humans with TLE. Cortical slow waves followed an Up and Down state firing pattern on MUA recordings, like the slow wave sleep state (n= 6 animals). Further, there is a decrease in cholinergic input to the cortex during seizures, with larger decreases associated with impaired behavior (n= 5 animals).
Translational Research