In behavioural research, internal states are measured through novelty responses. The way an animal responds to novel stimuli in the environment depends on its internal state (e.g., motivational drives), as determined by interacting neural and neurotransmitter systems (Horstick, Mueller, and Burgess, 2018). Animals that have recently had a stressful experience, for example, are more likely to be wary of novel stimuli.
Larval zebrafish (Danio rerio) are highly sensitive to light (Burgess and Granato, 2007). They display regular rates of motion while swimming under even illumination, and can react to a sudden change in light with stereotyped locomotion alterations. This makes them ideal for studies of internal states (De Marco et al., 2016) and behavioural screens. The Zantiks MWP_vb unit allows measuring the activity of multiple larvae and control light of varying power and wavelength.
Experimental set up
Larval zebrafish are placed individually in each well of a 6, 12, 24, 48 or 96 well plate.
The multi well plate with larvae is inserted into the chamber of the Zantiks MWP_vb unit. The script can be written to control single or multiple pulses of light - of varying length and known power and wavelength - as well as control of the system's temperature. Locomotor activity of each larva (measured as distance travelled) is measured and written to a data file at the frequency required by the experimenter.
Zebrafish larvae in a 24-well plate during two consecutive 120sec pulses of light (intertrial interval, 120sec). Speed 8x.