Noninvasive three-state sleep-wake staging in mice using electric field sensors

Abstract

Study Objective: Validate a novel method for sleep-wake staging in mice using noninvasive electric field (EF) sensors.Methods: Mice were implanted with electroencephalogram (EEG) and electromyogram (EMG) electrodes and housed individually. Noninvasive EF sensors were attached to the exterior of each chamber to record respiration and other movement simultaneously with EEG, EMG, and video. A sleep-wake scoring method based on EF sensor data was developed with reference to EEG/EMG and then validated by three expert scorers. Additionally, novice scorers without sleep-wake scoring experience were self-trained to score sleep using only the EF sensor data, and results were compared to those from expert scorers. Lastly, ability to capture three-state sleep-wake staging with EF sensors attached to traditional mouse home-cages was tested.Results: EF sensors quantified wake, rapid eye movement (REM) sleep, and non-REM sleep with high agreement (>93%) and comparable inter-and intra-scorer error as EEG/EMG. Novice scorers successfully learned sleep-wake scoring using only EF sensor data and scoring criteria, and *

Scoring sleep using respiration and movement-based features

“…There are unique movement patterns for each arousal state that can be measured using several technologies [1] , [2] , [3] , [4] . The sleep scoring method presented here uses movement-based detection of respiratory and gross body movements to distinguish between wake, rapid eye movement (REM) sleep, and non-REM sleep in mice without electroencephalogram (EEG), electromyogram (EMG) or video.…”

Relating spinal injury-induced neuropathic pain and spontaneous afferent activity to sleep and respiratory dysfunction

“…Sleep was analyzed from the EF sensor home cage recordings. As described previously 44,46 , wake, rapid eye movement (REM) sleep, and non-REM sleep were quantified through changes in animal movement and respiration (Figure 1B). Weekly averages were calculated for total sleep time (TST), percent time spent in each arousal state, average sleep bout duration (SBD), average REM sleep event duration, REM sleep latency, percentage of sleep bouts containing REM sleep, sleep fragmentation index (SFI: total awakenings per hour of sleep), and micro arousal index (MAI: total micro arousals < 60 seconds per hour of sleep).…”

“…Home cages (32 x 18 x 14cm, Super Mouse TM microisolator), described previously 42,44 , were instrumented with electric field (EF) sensors (Plessey Semiconductors, PS25251, 1 cm 2 , +/-5V, 1 kHz sampling) able to passively translate disruptions of the local electric field caused by movement into a voltage trace. EF sensors have been validated against respective gold standard techniques to reliably quantify resting respiration, sleep-wake staging (including differentiating rapid eye movement sleep, REM, from Non-REM sleep), and animal motor activity noninvasively from outside the animals' home cage 42,44 . Animals were acclimated to their instrumented home cages for several days prior to recording (Figure 1A).…”

“…The technological advance of the EF sensors has enabled noninvasive quantification of sleep changes in rodents after SCI 44 . Though the time spent asleep during the 12-hour dark cycle (6pm-6am) was unchanged, SCI animals had more fragmented and lower quality sleep relative to their sham and naïve counterparts.…”

“…To better quantify spontaneous pain and address limitations of existing pain assays, we explore novel physio-behavioral indices after SCI. In the thoracic contusion SCI model of neuropathic pain, we examine metrics associated with sleep architecture and respiratory function during natural behavior in the animal's home cage using non-invasive electric field sensors 42,44 . We also compare these behavioral outcomes to established mechanical sensitivity testing, along with terminal experiment observations of spontaneous activity in whole DRGs, below the level of injury.…”