Science - important! Optogenetics revealhow the brain produces perception.

Exploring the mysteries of neuroscience with rigorous academic logic thinking, edited by Wang Sizhen Wang Sizhen's large-scale and fine-scale monitoring of brain activity helps us understand the complexity of the brain, which is manifested in how the brain reacts and presents to the external world.although some studies have shown that many characteristics of brain activity patterns (such as which brain cells are activated and when) are related to changes in the external perception world, it is not clear which activity features are the result of perception and how they are combined to produce perception [1-3].in addition, some studies have shown that many activity-related changes may be redundant or even incidental [4-5].Professor Dmitry rinberg of New York University Neuroscience Center and langney health center has long been engaged in the research of olfactory, neuron, olfactory bulb, olfactory perception and olfactory pathway.published online in science on June 19, 2020, with the topic of manipulating synthetic optogenetic agents returns the coding logic of olfactory perception, they paid close attention to one of the major scientific issues, that is, how the brain generates perception.in order to answer this question, the researchers directly and systematically manipulated the neural activity of the olfactory system in mice and measured the sensory response.this is based on the fact that mouse olfaction is an attractive model system, and the related brain circuits have been described in detail. Therefore, mouse olfactory is more convenient to operate and study.at the same time, the authors carried out optogenetics techniques on omp-chr2-yfp transgenic heterozygous mice (experimental group) and B6 (CG) - tyrc2j / J (albino B6) mice (control group). In short, as long as the mice were exposed to light, brain cells were activated.therefore, photogenetics allows us to directly generate and manipulate brain activity in a precise and parametric manner.first, the researchers trained mice to recognize light driven activity patterns in their olfactory systems, known as "synthetic odors" patterns.subsequently, the researchers measured how cognitive abilities changed during the operation of the learning activity model.the related operations caused more cognitive changes in mice, and the degree of change reflected the importance of each operation feature to perception.secondly, by manipulating multiple features at the same time, researchers can accurately quantify how individual features combine to produce perception.for the results of this paper, firstly, the researchers found that the perceptual response of mice depends not only on which cells are activated, but also on the activation latency of such cells, i.e. time series (similar to timing notes in melody).the authors noted that the most perceptual activation latencies were associated with certain cells in a specific time series, such as the mitral tufted cells in the olfactory bulb, but not with brain or body rhythms (such as animal sniffing), which is inconsistent with some previous results [6-7].secondly, the authors found that in the time series, the cells activated earlier had a greater impact on the behavioral response, and the later cells in the sequence were modified, but the effect was very small.then, in order to further explain all the above results, the author developed a simple computer model based on template matching to compare the new activity sequence with the learned sequence or template. the model further measures the relative time in each sequence and illustrates the importance of earlier activation of cells. finally, based on the above model, the degree of mismatch between the new sequence and the learned template predicts the degree of decline in recognition ability when neural activity changes in many different operations. detect olfactory perception with synthetic odors (a) recognize synthetic odor patterns by training mice: artificially stimulating neural activity in the olfactory bulb, and defining these patterns on spatial (upper right) and temporal (lower right). (b) the perception response was measured by systematic operation of training mode. (c) template matching model of pattern activity (left) explains perceptual response (right). (photo: Edmund Chong, et al., science 2020; 368) conclusion in general, the researchers propose an experimental and theoretical framework to help draw precise and systematically manipulated brain activity patterns. secondly, using this framework, the author reveals the key computational model of olfactory system for perception of neural activity, and deduces the specific model of olfactory processing directly related to perception. and the framework forms a powerful and universal method for measuring the causal link between brain activity and perception or behavior. in addition, this framework is particularly relevant and instructive when considering the advanced tools of follow-up development for fine and large-scale manipulation of brain activities in different brain regions. [2] C. A. Runyan, e. piasini, S. panzeri, C. D. Harvey, distinct timescales of population coding across cortex. Nature 548, 92 – 96 (2017). [3] A. R. houweling, M. Brecht, Behavioural report of single neuron stimulation in somatosensory cortex. Nature 451, 65–68(2008).【4】M. Smear, R. Shusterman, R. O’Connor, T. Bozza, D. Rinberg, Perception of sniff phase in mouse olfaction. Nature 479, 397–400 (2011)【5】M. Smear, A. Resulaj, J. Zhang, T. Bozza, D. Rinberg,  Multiple perceptible signals from a single olfactory glomerulus. Nat. Neurosci. 16, 1687–1691 (2013).【6】R. Iwata, H. Kiyonari, T. Imai, Mechanosensory-based phase coding of odor identity in the olfactory bulb. Neuron 96,1139–1152.e7 (2017). 【7】K. A. Bolding, K. M. Franks, Recent continental circuits implementation concentration invariant odorcoding. Science 361, eaat6904 (2018). Plate making Wang Sizhen