Now that there's enough data, we're looking for stories in that data – trends, vector changes and accelerations, anomalies, that kind of thing," said Fruhlinger.
Three marine species were exposed to playback noise, provided as examples of behavioural responses to impulsive sound at 163 171 dB re 1 μPa (peak-to-peak SPL) and continuous sound of 142.7 dB re 1 μPa (RMS, SPL), exhibiting directional changes and accelerations.
Thus PN respond mainly to odor rate of change and acceleration.
Since the output of the forward difference equation is sensitive to high-frequency components of the signal, we low-pass filtered the amplitude and rate-of-change signals before deriving the rate of change and acceleration, respectively.
Therefore, we reasoned that the computation of the first and second time derivatives (rate of change and acceleration) of odor concentrations by OSN and PNs, respectively, acts to advance peak times of olfactory stimuli.
For the correlation analysis and 2D model prediction, the rate of change and acceleration components of odor and OSN traces were estimated by a forward difference equation, with the difference time interval as the scaling factor; for example, d x d t = [ x (t − Δ ) − x (t ) ] / Δ, where x represents either the odor concentration or the OSN response, and Δ denotes the time interval.
Three parameters (rate of change occurrence, rate of change spreading and acceleration of change-contagion) control the order of cells order in the queue, and ultimately determine the emergence and extent of patches-of-change.
In comparison, the proposed tracker managed to maintain smooth tracking despite sudden orientation changes and large acceleration (Figs. 14, 15, 16, and 17).
