Guangwei Si's research while affiliated with Harvard University and other places

Publications (22)

Article
Full-text available
Animal behavior is shaped both by evolution and by individual experience. Parallel brain pathways encode innate and learned valences of cues, but the way in which they are integrated during action-selection is not well understood. We used electron microscopy to comprehensively map with synaptic resolution all neurons downstream of all Mushroom Body...
Preprint
Olfactory systems employ combinatorial receptor codes for odors. Systematically generating stimuli that address the combinatorial possibilities of an olfactory code poses unique challenges. Here, we present a stimulus method to probe the combinatorial code, demonstrated using the Drosophila larva. This method leverages a set of primary odorants, ea...
Preprint
Animal behavior is shaped both by evolution and by individual experience. In many species parallel brain pathways are thought to encode innate and learnt behavior drives and as a result may link the same sensory cue to different actions if innate and learnt drives are in opposition. How these opposing drives are integrated into a single coherent ac...
Article
Odor perception allows animals to distinguish odors, recognize the same odor across concentrations, and determine concentration changes. How the activity patterns of primary olfactory receptor neurons (ORNs), at the individual and population levels, facilitate distinguishing these functions remains poorly understood. Here, we interrogate the comple...
Article
Full-text available
Somatic stem cells constantly adjust their self-renewal and lineage commitment by integrating various environmental cues to maintain tissue homeostasis. Although numerous chemical and biological signals have been identified that regulate stem-cell behaviour, whether stem cells can directly sense mechanical signals in vivo remains unclear. Here we s...
Data
Cytosolic Ca2+ activities in StimRNAi + InsP3RRNAi fly midguts under mechanical compression
Preprint
Full-text available
Animals can identify an odorant type across a wide range of concentrations, as well as detect changes in concentration for individual odorant type. How olfactory representations are structured to support these functions remains poorly understood. Here, we studied how a full complement of ORNs in the Drosophila larva encodes a broad input space of o...
Preprint
Full-text available
The sense of smell enables animals to react to long-distance cues according to learned and innate valences. Here, we have mapped with electron microscopy the complete wiring diagram of the Drosophila larval antennal lobe, an olfactory neuropil similar to the vertebrate olfactory bulb. We found a canonical circuit with uniglomerular projection neuro...
Preprint
Full-text available
Neural circuits for behavior transform sensory inputs into motor outputs in patterns with strategic value. Determining how neurons along a sensorimotor circuit contribute to this transformation is central to understanding behavior. To do this, a quantitative framework to describe behavioral dynamics is needed. Here, we built a high-throughput optog...

Citations

... Recent anatomical work done on the D. melanogaster brain connectome using electron microscopy techniques has revealed major new insights into the role of the lateral horn as a hub for multisensory inputs as well as associative learning. [54][55][56] The neuronal substrates in the lateral horn and further downstream centers that may also play a role in these behaviors remain largely elusive so far and are therefore rich candidates for exploring the basis of multimodal integration. ...
... These arguments would suggest that the timescales measured in reverse correlation should be similar to the actual timescales of the sensory neuron filters. Indeed, electrophysiological (Schulze et al., 2015;Gorur-Shandilya et al., 2017) and optical (Si et al., 2017) recordings in olfactory sensory neurons reveal that these neurons filter odor inputs with similar dynamics to those observed in our behavioral reverse correlation experiments. ...
... While the number of neurons that were targeted in our tested lines varies from one to seven pairs on average, and sometimes more, in the case when the lines label multiple neuron types, intersectional strategies can be used to further refine the expression patterns. In the larva, a volume of electron microscope data has been acquired and more than 60% of the nervous system has been reconstructed through collaborative efforts [10,21,22,24,25,27,29,[47][48][49]. The synaptic partners of the identified candidate neurons can therefore be further reconstructed in the electron microscopy volume. ...
... Neuron types in various organisms have been classified based on their function (28,31,90,91,162), morphology (10,89), gene expression (86)(87)(88), or combinations of features (10,13,93), such as morphology and connectivity. While it is reasonable to expect that all these features are correlated, it is still unclear which one is ideal for defining neuron types and how neuron types defined based on different features correspond to each other. ...
... Androstadienone is detected at varying concentrations by different individuals, which is similar to many other odors and pheromones; furthermore, it may function as a subliminal odor, or vasana, which operates below the threshold of conscious odor detection [3]. It is known that the activity of olfactory receptor neurons correlates with odorant concentration across a variety of odorants in Drosophila models [16], suggesting a common set of olfactory receptors leading to these differences in androstadienone sensitivity, contributing to its varying role as a pheromone, vasana, or odor. Furthermore, mRNA expression has been shown to change in response to odor concentrations [17], suggesting further that a common set of olfactory receptors for androstadienone may mediate its varying conscious and subconscious effects. ...
... Organoid systems will also be useful for studying the role of forces in intestinal epithelia using biophysical tools such as optical tweezers, atomic force microscopes and force sensors. The intestine undergoes strong peristaltic movements and is under constant pressure from its contents and stretch-activated channels regulate stem cell differentiation in response to mechanical forces [91]. ...