RAMP: from intuition to science

Lets begin with fish, but the discussion applies to all other animals that have reflex actions.  Every fisher, commercial or recreational, intuitively knows and expresses opinions about the vitality of their fish, either in the water or caught. Excitedly proclaiming fish on and then proceeding to catch the fish, admire its size, and then release, sell, or eat the fish. These intuitive observations are grounded in our sense of vitality that is an expression of activity and responsiveness.

Intuitive notions are great for telling fish stories and are notoriously fallible when the size or fight of the fish in question is described to other bystanders. But these notions can lead to a quantitative expression of animal vitality that is grounded in solid, repeatable, and predictive science. How do we do this?

Vitality can be an expression of activity, which is diminished in stressed, lethargic fish.  Stress is an adaptive response to stressors. When fish are stressed too much or for too long, they can become diseased or die, states that do not support healthy populations and species diversity. So this loss of vitality that we intuitively observe can have profound consequences. To understand and ameliorate these consequences, we need good quantitative science.

For the purposes of describing and quantifying animal vitality and its inverse, mortality, we can start with animals in good condition and health that have a full suite of reflex actions and then study how stressors impair reflex actions until the end point of death. We use the presence or absence of reflex actions because these are fixed involuntary actions that are directly related to vitality and not subject to the effects of animal size and voluntary, complex behaviors such as feeding, social interactions, predator-prey interactions, migration, and sex, which can be modified by temperature, light, food availability, motivation, avoidance, and attraction.

We use a calculated quantitative index of reflex impairment, RAMP, that combines the presence-absence scoring of several reflex actions. RAMP is an integrative index that communicates the vitality of a whole animal. Similar reflex-based indices are used in human medicine to evaluate general health, neurological condition, and potential outcomes for coma and other non-communicating patients, as well as for triage of emergency patients.

Identifying appropriate reflex actions is where the imagination expands. We have got to figure out how to "tickle" the animal. What stimuli make it respond in the fixed involuntary patterns we call reflexes? Appropriate stimuli and testing modalities depend on the size of the animal and the logistical constraints of the situation. There are many human examples for inspiration.

Lets look at reflex actions through a continuum of animal size and activity for examples.  This list is by no means complete. Reflex actions can be tested in fish larvae by observing free swimming animal startle, orientation, and avoidance in response to light, sound, food scent, and touching with a probe.  For juveniles, fish can be restrained and tested for body flex upon restraint where fish attempt to escape when restrained, dorsal fin erection in which the fins become erect when fish are restrained, operculum and mouth closure where the operculum or mouth clamps shut when lifted or opened, the gag response where the fish opens its mouth and flexes the body when the throat is stimulated and the vestibular–ocular response (VOR) shown by eye rolls when the body is rotated around the long axis. For free swimming fish, studied reflexes included orientation where the fish should normally be upright, righting reflex where the fish returns to an upright position and the startle response in which the fish shows rapid forward motion in response to stimuli. Adult fish can present special problems because of their strength and other approaches for free swimming fish are described in another post. Sharks and other dangerous toothy or spiny animals especially need imaginative approaches to testing reflex actions.

Once a suite of reflex actions can be consistently observed and easily quantified, then building a RAMP curve can be accomplished and quantification of reflex impairment, vitality, and prediction of mortality is made possible. The RAMP method and curves developed then allow for the systematic investigation of the effects of stressors and stress in animals and systems of chosen interest. RAMP results can be compared and contrasted with concurrent results from physiological and physical injury studies in an effort to synthesize multivariate solutions to a continuum of important basic and applied questions. These questions may include understanding reflex biology, stress biology, fisheries management, bycatch reduction, animal health, population dynamics, aquaculture practices, migration biology, reproductive biology, and conservation biology to mention a few.