Portable Functional Near-Infrared Spectroscopy for Investigating the Resilience and Vulnerabilities of the Marine Mammal Brain
Abstract
Oceanic noise including military sonar has remained one of the most controversial and debated stressors affecting marine mammal populations for over two decades. Although exposure to anthropogenic noise has been linked to numerous mass stranding events involving deep-diving cetaceans, identifying the actual cause of injury has been difficult. Scientists are just now beginning to understand how marine mammals respond to disturbance. Communication and diving behaviors essential to the survival of these animals are adversely affected by exposure to anthropogenic noise. Behavioral and tissue pathologies of beaked whales following stranding suggest cognitive disfunction. Most recently, we have reported that extreme cardiovascular changes associated with escape responses from aversive stimuli such as noise may challenge blood flow to the brain of diving mammals with potential sublethal and lethal impacts. How cetaceans and other marine mammals maintain oxygen delivery to the brain and avoid cerebral injury during these challenges is unknown, but can now be discerned with new advances in portable, non-invasive instrumentation for functional brain monitoring. In this project we will take advantage of these timely technological developments to acquire state-of-the-art instrumentation and equipment to establish a neurophysiology lab for measuring the functional biology of the marine mammal brain. Studies will range from assessing resilience to sleep and oxygen deficits to identifying vulnerabilities to man-made disturbance. This Comparative Marine Mammal Brain Lab will support investigations of blood flow, oxygenation, metabolic status, and electrical activity level of the cetacean and pinniped brain from skin surface monitors during active swimming, sleep, diving, and breath-holding. This will be accomplished by using newly available, portable near-infrared spectroscopy (NIRS), ultrasound, and electroencephalography (EEG) monitors adapted from clinical medicine to application in swimming mammals. The core instrument is a compact, submersible NIRS monitor that instantaneously records changes in brain oxygenation from changes in oxy-hemoglobin and deoxy-hemoglobin concentrations (Brite System, Artinis Medical Systems, The Netherlands). The NIRS system will be calibrated on trained marine mammals in controlled settings via standard doppler blood flow from transcranial ultrasound (Sonosite Vet Edge II, Bothell WA) and electroencephalography (AdInstruments, Colorado Springs, CO). Together with our custom heartrate monitors, these instruments will enable the first integrated cardio-neural profiles of brain function for free-ranging marine mammals. Furthermore, the project represents the next step in our ongoing investigations of the impacts of noise on marine mammals with an overall objective of improving the protection of marine mammals during Naval operations. Importantly, the proposed lab is strategically located at the marine mammal facilities on the University of California- Santa Cruz (UCSC) offering unprecedented access to trained and wild marine mammals, and unique opportunities for research by students and national/international collaborators. Designated as both a Hispanic-Serving Institution and Research 1 University, UCSC is dedicated to training a diverse undergraduate and graduate STEM cohort that includes schools in the South Bay and Monterey region. Elucidating brain function during periods of oxygen and sleep deprivation is appealing to both these students and the broader public given its application to mammal conservation as well as to human neural pathologies such as insomnia, stroke, concussion or other oxygen-mediated neural injuries. Furthermore, it represents the next step in our ongoing investigations of the impacts of noise on marine mammals with an overall objective of improving the protection of marine mammals during Naval operations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 24, 2019
- Source ID
- N000141912178
Entities
People
- Terrie M. Williams
Organizations
- Office of Naval Research
- United States Navy
- University of California, Santa Cruz