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Social Transmission of Food Preference (STFP) is a single trial non-aversive learning task that is used for testing non-spatial memory. This task relies on an accurate estimate of a change in food preference of the animals following social demonstration of a novel flavor. Conventionally this is done by providing two flavors of powdered food and later estimating the amount of food consumed for each of these flavors in a defined period of time. This is achieved through a careful measurement of leftover food for each of these flavors. However, in mice, only a small (~1 g) amount of food is consumed making the weight estimates error prone and thereby limiting the sensitivity of the paradigm. Using multiplexed video tracking, we show that the pattern of consumption can be used as a reliable reporter of memory retention in this task. In our current study, we use this as a measure and show that the preference for the demonstrated flavor significantly increases following demonstration and the retention of this change in preference during remote testing is flavor specific. Further, we report a modified experimental design for performing STFP that allows testing of change in preference among two flavors simultaneously. Using this paradigm, we show that during remote testing for thyme and basil demonstrated flavors, only basil demonstrated mice retain the change in preference while thyme demonstrated mice do not.

Wireless Laser Communication (WLC) is emerging as an effective last mile solution for high rate data transmission. It consists of a transmitter, a receiver and the atmosphere as an unguided propagation medium. The transimpedance design based optical receivers employed till now still involve an unwanted compromise between bandwidth and noise, both of which are influenced by the capacitance of the photodiode. We suggest an Operational Transresistance Amplifier (OTRA) based receiver section for the link arrangement. The OTRA is a new building block in the field of analog signal processing. We show that it highly improves upon the compromise between bandwidth and noise. We also show how the proposed receiver section highly improves upon the contemporary receiver designs and provides several unique and useful advantages using an OTRA based band pass filter employed in the receiver section.

The intensity required to optically saturate a chromophore is a molecular property that is determined by its absorption cross section (s) and the excited state lifetime. We present an analytical description of such a system and show that fluorescence around the onset of saturation is characterized by product of absorption cross section and lifetime. Using this approach we formulate a generalized method for measuring the multiphoton cross section of fluorophores and use it to obtain the absolute three-photon cross-section spectra of tryptophan. We find that the tryptophan three-photon cross section ranges from 0.28 S.I. units (m ) at 870 nm to 20 S.I. units at 740 nm. Further, we show that the product of molecular rate of excitation and de-excitation, denoted as b, serves as a vital contrasting agent for imaging local environment. Our contrast parameter, b, is related to fraction of the population present in the excited state and is independent of the fluorophore concentration. We show that b-imaging can be carried out in a regular two-photon microscope setup through a series of intensity scans. Using enhanced green fluorescent protein (EGFP) fluorescence from the brain slices of Thy-1 EGFP transgenic mice, we show that there is an inherent, concentration independent, variation in contrast across the soma and the dendrite.

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