The Latest: Man-made perception? Scientists reveal the logic behind neuronal coding perception.

Learn about the latest progress in neuroscience ● click on the blue character to pay attention to us ● when we are adults walking in our childhood primary school again, when we see the blurred chalk characters on the wall, many interesting things about primary school are aroused, with a smile on the corner of the mouth and immersed in memory.in fact, in addition to memory awakening, there is another abstract thing - perception.perception is the reflection of the brain to the overall attributes of objective things on the basis of feeling, while feeling is only the reflection of the brain on some attributes of objective things, such as pain, taste, hearing, vision, etc.the picture is quoted from: in the process of perception, there are many spatial and temporal characteristics: when and where the neurons in the brain respond according to what mode.in fact, the complexity of perception is much more than that.in the process of perception, these spatial and temporal characteristics also change, so it is difficult to distinguish their independent contributions to perception.on June 19, 2020, the team of Dmitry rinberg from the Institute of neuroscience, longney medical center, New York University, first revealed the neuroscience logic of olfactory bulb perception using the classic olfactory system in science.human olfactory system can distinguish thousands of odors. Olfactory sensory neuron axons can accurately transmit odor related information to glomeruli. Each olfactory bulb can form synapses with 20-50 mitral tufted cells (MT cells) to process odor information and finally transmit it to olfactory cortex.the researchers have done a job of opening the brain cavity. After point stimulation, MT cells are activated (the range of point stimulation is 120 square microns), which causes the discharge frequency of MT cells to reach 100Hz and the duration of neuronal excitability is about 80ms, which can simulate the neuronal activation mode related to the odor of existing chemicals.although there are differences in neuronal activity induced by light stimulation and odor activated neurons by chemicals, the stimulation duration and activation latency of this artificial activation mode are within the range of odor induced neuronal activity.the target mode and non target mode of artificial stimulation of olfactory bulb of mice, pictures from literature 1. Through this stimulation mode, the mice were trained to distinguish the target odor from the non target odor. When the mice were stimulated at six points in a specified time to simulate the odor stimulation (this activation mode includes spatial and temporal characteristics), the mice were pressed The water reward will appear after the rod, which is called the target mode activation; when the mice are randomly stimulated for 6 points, the water reward does not appear when the mice press the rod, which is called the non target mode activation.through such a behavior model, researchers try to observe the behavior changes of mice after disturbing the target odor pattern by changing the time and sequence of point stimulation. There is a difference between the proportion of water reward successfully obtained by disturbing and the proportion of water reward obtained by normal target odor training, which is called perceptual distance.the researchers adjusted the activation mode - the time of light activation was unchanged, but the point stimulation of target mode was replaced by the point activation of non target mode, so as to observe the effect of disturbing spatial features on olfactory.they found that the more the number of points to be replaced, the lower the success rate of water reward in mice, that is to say, it has a great impact on the olfactory function of mice; when the position order of the replaced points is higher, the effect of the first three points in the replacement target mode is greater than that of the three points after the replacement).the researchers kept the position of the point stimulus of the target mode unchanged, but advanced or delayed the activation time, trying to observe the effect of temporal characteristics on olfaction.results it was found that changing the time of point stimulation at the front of the position sequence had a great influence on the olfactory function of mice, but the effect of changing the stimulation time at the back of the position on mice was small.more interestingly, the researchers delayed the stimulation time of target mode points by one time point, which had little effect on the olfaction of mice. in System Neuroscience, system matching model can well compare the temporal and spatial characteristics of neurons. the researchers matched the target activation pattern (regarded as learned pattern) and the new activation pattern (regarded as new input pattern), and the degree of mismatch between them changed with the change of neuron activity. they found that in this model, the order of stimulation of the replaced points in the spatial sequence had the least effect on the olfactory function of mice, and the effect of changing the activation time of the point in the time series was more significant. in general, this paper decodes how the brain perceives odors through the artificial simulated odor stimulation of optogenetics, and reveals how the brain neurons transform sensory information into perception by taking olfaction as an example. References: 1. Chong et al., manipulating synthetic optogenetic doors reveal the coding logic of olfactory perception; science 368, eaba2357 (2020)