Biology subjects

Liran, O.

Publications and source records attributed to Liran, O..

4 recordsLinked to original sources

bioRxiv2023

Recording neural reward signals in the real-world using mobile-EEG and augmented reality

The electrophysiological response to rewards recorded during laboratory-based tasks has been well documented over the past two decades, yet little is known about the neural response patterns in real-world settings. To address this issue, we combined a mobile-EEG system with an augmented reality headset (which blends high definition "holograms" within the real-world) to record event-related brain potentials (ERP) while participants navigated an operant chamber to find rewards. 25 participants (age = 18-43, Male=6, Female=19) were asked to choose between two floating holograms marking a west or east goal-location in a large room, and once participants reached the goal location, the hologram would turn into a reward (5 cents) or no-reward (0 cents) cue. Following the feedback cue, participants were required to return to a hologram marking the start location, and once standing in it, a 3 second counter hologram would initiate the next trial. This sequence was repeated until participants completed 200 trials. Consistent with previous research, reward feedback evoked the reward positivity, an ERP component believed to index the sensitivity of the anterior cingulate cortex to reward prediction error signals. The reward positivity peaked around 235ms post-feedback with a maximal at channel FCz (M=-2.60V, SD=1.73V) and was significantly different than zero (p < 0.01). At a behavioral level, participants took approximately 3.38 seconds to reach the goal-location and exhibited a general lose-shift (68.3% {+/-} 3.5) response strategy and were slightly slower to return to the start location following negative feedback (2.43 sec) compared to positive feedback (2.38 sec), evidence of post-error slowing. Overall, these findings provide the first evidence that combining mobile-EEG with augmented reality technology is a feasible solution to enhance the ecological validity of human electrophysiological studies of goal-directed behavior and a step towards a new era of human cognitive neuroscience research that blurs the line between laboratory and reality.

neuroscience↗

bioRxiv2023

Solar Induced Fluorescence Retrieved from Avocado (Persea americana Mill.) Canopies Along the Season Correlates with Sugar Levels in the Developing Fruit

Solar Induced Fluorescence (SIF) emitted from the photosynthetic apparatus is related indirectly to biomass production. It can be remotely sensed from airborne platforms, yet, the spatial resolution from satellites, for example, is too low for commercial agricultural uses. We used a non-imager point spectroradiometer mounted on SIF-UAV (Unmanned Aerial Vehicle) system, and retrieved SIF at high spatial resolution, which is fitted for precision agriculture applications. In this study, we tracked the spatial variation of SIF along the season over a commercial avocado (P. americana Mill) orchard. The retrieved SIF signals were Krieg-interpolated to create a continuous SIF layer that allowed the estimation of SIF values for each tree in the orchard. We show that the SIF signal retrieved over the canopies in the main fruit development stage is highly correlated with the levels of sugars accumulated in the ripening avocado fruit. It established the foundations for high-spatial resolution detection of the natural variation of photosynthesis activity, which may lead to in-season adjustments of agronomic inputs using precision agriculture technologies.

plant biology↗

bioRxiv2022

Limitations of Solar-Induced Chlorophyll Fluorescence (SIF) for Estimating Photosynthesis Under Stress

High-throughput measurements of photosynthesis of plants grown under various conditions may provide important insights into the plasticity of the photosynthetic performance of plants. Remote sensing of photosynthetic activity is the next generation of fast scanning techniques, enabling high-throughput photosynthesis measurements under controlled conditions. We hypothesized that by measuring SIF simultaneously with whole-plant water relations in a standardized controlled drought experiment, we would be able to quantify photosynthetic activity and to detect water stress at an early stage. A functional-phenotyping platform was used to apply the controlled drought treatment and to monitor the growth and water balance of tomato introgression lines (ILs). A new SIF-derived index, electron transport rate (RS-ETRi), was found to be negatively correlated with whole-plant stomatal conductance (Gsc) under non-stressed conditions. No significant relationships were found between SIF and plant biomass or Gsc. SIF687 responded to drought earlier than any of the other measured vegetation indices. SIF based indices could not differentiate between introgressed lines of tomato; whereas differences between Introgression Lines were clearly identified by the water-relations measurements. We concluded that SIF did not provide any advantage over commonly used methods for detecting physiological differences between the Introgression Lines. Overall, although SIF plays a significant role in photosynthesis, the relationship between SIF and photosynthesis is complex and we believe it would be an oversimplification to use SIF to quantify photosynthetic activity on close canopy spatial resolution level.

plant biology↗

bioRxiv2021

Power dynamics of theta oscillations during goal-directed navigation in freely moving humans: A mobile EEG-virtual reality T-maze study

Theta oscillations ([~]4-12 Hz) are dynamically modulated by speed and direction in freely moving animals. However, due to the paucity of electrophysiological recordings of freely moving humans, this mechanism remains poorly understood. Here, we combined mobile-EEG with fully immersive virtual-reality to investigate theta dynamics in twenty-two healthy adults (aged 18-29 years old) freely navigating a T-maze to find rewards. Our results revealed three dynamic periods of theta modulation: 1) theta power increases coincided with the participants decision-making period; 2) theta power increased for fast and leftward trials as subjects approached the goal location; and 3) feedback onset evoked two phase-locked theta bursts over the right temporal and frontal-midline channels. These results suggest that recording scalp EEG in freely moving humans navigating a simple virtual T-maze can be utilized as a powerful translational model by which to map theta dynamics during "real-life" goal-directed behavior in both health and disease.

neuroscience↗