Integrated EEG/NIR Sensor System for Infants

DESCRIPTION (provided by applicant): The long-term objective of the proposed project is to design a cost-effective, light-weight, integrated, whole- head EEG/NIR brain imaging and data analysis system for non-invasive recording of brain activity in neonates and young children. This system will permit bedside monitoring of immediate at-risk neonates, and early identification and intervention for abnormalities that predict developmental disabilities and cognitive deficits. A dense-array of 128 combined opto-electrodes sitting on the surface of the scalp will simultaneously record brain electrical activity (electroencephalography, EEG), and cerebral blood oxygenation changes (near-infrared spectroscopy, NIRS), providing complementary measures on the timing and location of brain function. For Phase I, the first Specific Aim is to develop a prototype EEG/NIR sensor net for neonates. Source and sensor opto-electrodes will be assembled into a flexible polymer web (building on EGI's existing geodesic net structure used for 128-channel EEG recording). In addition to housing silver-silver chloride electrodes for EEG acquisition, each source opto-electrode will contain miniature dual-wavelength LEDs for transmitting NIR flux into the head and each detector opto-electrode will contain light detectors and pre-amplifiers for measuring recovered NIR flux (the fractional flux changes being related to changes in oxygenated and deoxygenated hemoglobin concentrations). Miniature shielded wires will connect the opto-electrodes to subsystems that either drive modulated currents to the source LEDs or perform analog-to-digital conversion of the EEG and NIR signals. Multiple unique modulation frequencies will make it possible to drive and distinguish all light sources at detectors using FFT demodulation. EEG, NIR, experimental stimuli, and other recorded physiological signals (e.g., EKG, EMG) will be synchronized using EGI's existing Amp Server technology. Through iterative in-house testing, the infant net and system design will be further refined to improve sensor contact, minimize movement artifact, address comfort and stability, and ensure practical usability of the system as a whole. The second Specific Aim is to field-test the prototype system for data integrity, functionality and usability. Simultaneous resting state EEG and NIR data will be collected on 10 neonates within 24 hours of birth through collaboration with the Subcontractor, who has research privileges at a neonatal hospital unit and expertise in neonatal dense-array EEG. The opto-electrode net will be formally evaluated for fit, safety and comfort, including sensor positioning, contact and pressure, and ease of application. EEG data integrity will be assessed by expert review for comparability to resting EEG data previously collected with EGI's standard HCGSN EEG system in terms of signal quality, and noise and movement artifact. NIRS data integrity will be assessed for fall-off in signal recovery with distance from emitters that is consistent with the computational model of optical diffusion, and for the presence of a readily identifiable cardiac pulse. Aim 3 is to define the architecture for a commercially viable integrated EEG/NIR system for infants and the path for developing it within Phase II. PUBLIC HEALTH RELEVANCE: The goal of this project is to develop the first lightweight device capable of providing real-time spatial and temporal brain imaging information regarding newborn and young infant neural functioning. Such a development would facilitate bedside monitoring of immediate at-risk newborns and offer us the incredible opportunity to identify in very young infants the structural and functional abnormalities that may contribute to later emerging developmental disabilities. Such early identification is vital to the development of early interventions that may mitigate or even preclude the emergence of the disorder.