New life sciences paper reviews: command neurons involved in feeding behavior of Drosophila connecting the memory formation and synaptic plasticity
In the laboratory of the author, and adult Drosophila that can be for the purpose of understanding the fundamental processes of memory, and the neuromuscular junction of Drosophila stainless steel buffet server is a model of a simple synapse, to relate directly to the storage as a change in behavior We study while comparing the two, the synapse of neural circuits responsible for the feeding behavior of. By act screening stainless steel buffet server the NP system is a conservative system of Gal4 insertion Drosophila, which is established by a consortium of Japan, it has been found Fdg neuron is a command neuron causes a feeding behavior when working. It is considered Fdg neurons to be located on the neural involved in feeding behavior, by using an experimental system newly developed for the purpose of simultaneously performing analysis electrophysiological and live imaging stainless steel buffet server and behavioral observations, Pavlov's conditioned reflex stainless steel buffet server I hope to be able to study as a change stainless steel buffet server in synaptic input to the neuron Fdg. Think by as a working hypothesis the results of the previous studies on synaptic plasticity at the neuromuscular junction of Drosophila, to analyze in detail along with the behavioral changes synaptic plasticity in this Fdg neurons, and will Semaro on the molecular mechanism of memory formation have. Introduction
The storage that is deeply in the hearts of us, with or forgot some of which last for a lifetime, after a while though it is memory that was very excited, memory is mysterious. Once, had been studied only as the theme of psychology, memory was an abstract concept elusive. stainless steel buffet server When was treated as experimental biology this memory, it is a conditioned reflex of Pavlov well-known to the public. Pavlov by stimulation of two distinct, set the sound of a bell and (conditioned stimulus) bait (unconditioned stimulus), to give the dog to the unconditioned stainless steel buffet server stimulus following the conditioned stimulus. Originally secretion of saliva stainless steel buffet server was a reaction stainless steel buffet server by the unconditioned stimulus, was caused sound of the bell alone (conditioned stimulus) (Figure 1a). In this case, that you have set the experiment is likely stainless steel buffet server to control was also important, but above all, by a simple condition setting of association with unconditioned stimulus and the conditioned stimulus, the neural stainless steel buffet server circuit as a mechanism lurking in the back of this associative learning It was clearly imagine the change in was important. However, it is not well understood yet Des speculative still, further, it will happen and how is the actual neural circuitry changes. Our lab is working with a new approach to the question remains as to which storage is that what is created.
1. It is believed that plasticity memory of synapses and is held by the neurons of a series linked via a synapse that has been strengthened by experience, neuroscientists that many have speculated, including the author. This is one that is formulated stainless steel buffet server for the first time in the 1940s, known as "synapses stainless steel buffet server Hebb" or "law Hebb" take the name of the advocate). The post-synaptic cell is ignited immediately after the synapse cells were firing before, only when there is a timing of postsynaptic and presynaptic this, synapses intensify specifically (Figure 1b). According to this thinking, how Pavlov's conditioned reflex or can be, can be explained very simply (Figure 1a). Assuming for the neurons that commander that the neurons that transmit signals sound of bell (conditioned stainless steel buffet server stimulus) is, give a saliva in response stimuli stainless steel buffet server feed the (unconditioned stimulus), and had formed a weak synapse Miyou. It should be firing neurons of these two in succession in the experiments of Pavlov, as a result, saliva stainless steel buffet server that will come out the sound of the bell alone (conditioned stimulus) by the Hebb rule, synapses between them becomes stronger I can guess as. Of course, there is no should be simple so amid the brain of the dog the actual neuron countless because should play this synaptic plasticity, this in practice in the brain that is intertwined cells of unrelated still many in disarray be examined is not easy. So first, it was thought to be investigated the mechanism lurking in the bottom of synaptic plasticity by Hebb rule in a simple stainless steel buffet server synapse. In this regard, a number of researchers is of from which we derive a substantial stainless steel buffet server knowledge in the experiment, such as long-term potentiation in the hippocampus of course, but first, the authors grab a process fundamental synaptic plasticity by simplifying the experiment stainless steel buffet server Because, a few of the possible physiological analysis of exact synapse), I have established an experimental system of plasticity at the neuromuscular junction of the Drosophila embryo by the detailed quantitative. From the results of the analysis anatomical analysis and electrophysiological at the neuromuscular stainless steel buffet server junction, a mutual between release and to create a micro-synaptic potential from the presynaptic and the retrograde signal emitted from the post-synaptic "local feedback 4 built a working hypothesis by state ", was strengthened in specific synapses one is whether not be maintained). This was likely derived from the experimental results at the neuromuscular junction, they will better explain the Hebb rule, and it fits well with existing literature, stainless steel buffet server the mechanism for the formation stored is maintained in the brain may lie. I felt a big dream to this possibility, but where it was studied stainless steel buffet server how much the neuromuscular junction that do not involved in memory in the brain actually, I can not zero in on the essence of memory. In order to verify in the brain the findings of the neuromuscular junction, and can move forward to the next stage. 2. Command neurons stainless steel buffet server
Well, what should I Musubitsukere stainless steel buffet server in synaptic plasticity and memory formation in the brain how? In a study using the sea hare in the 1980s, experimental approach of first five had a major insight that extends stainless steel buffet server to the molecular mechanisms of synapse stainless steel buffet server in fact). stainless steel buffet server However, due to the fact that it is modified by attaching directly to the presynaptic neurons responsible for unconditioned stimulus plays a conditioning stimulus, i.e., the synaptic specificity, stainless steel buffet server determined the specificity of the synapses by the anatomical stainless steel buffet server features Because I, not a model of synaptic by Hebb rule (Fig. 1c). Well, you dream that absurd to be, or Let's make the experimental system from scratch on their own. At this time, it was in the head keyword, "command neuron" this was a (command neuron). Stereotyped behavior 6, which is the concept of animal stainless steel buffet server behavior), for example, neurons corresponding to trigger that causes the behavior patterns of a series of fixed, such as egg-laying behavior and aggressive behavior is the command neuron. The concept of command neurons, 7 that stems from experiments or turn off or turn on the movement of the swimming leg of crayfish stainless steel buffet server in the 1960s). Neurons stimulate stainless steel buffet server the secretion of saliva, can be said to be command neurons causes a part of the feeding behavior that is understood by the departure bait. So I think you can find a command such neurons, as is absolutely necessary key to get into the next room. 2005 equivalent to 4) of the authors has published a study of the plasticity of the neuromuscular stainless steel buffet server junction, technology "remote control" of Drosophila was announced at just the right time 8) (Figure 2a). In this case, by connecting to the downstream of the UAS sequence that is the target sequence of the transcription factor Gal4 of budding yeast, the ATP receptor channel ignite stainless steel buffet server the cell by passing through toward the inside from the outside of the cell cation, expressing Gal4 were specifically expressed in cells only you have. And, by opening the ATP receptor channel by liberate ATP from caged ATP by the irradiation of light, it is ignite aiming only that cell. Means the arrival of the era of light genetics today subjugate the temporal and spatial activities of cells (optogenetics), this experiment was a truly revolutionary! Breakthrough. Say at that point, the command neurons in Drosophila is only neurons to cause escape behavior was induced escape behavior in Drosophila and ignite it in this experiment. However, escape behavior is unlikely work for the study of memory. So, is a rough policy stainless steel buffet server and that, trying to find a new command stainless steel buffet server neurons by ignite the cell of a random pattern by multiplying the Drosophila expressing the channel one and all the Drosophila Gal4 is inserted, stainless steel buffet server to screen the system a lot of have been seen. 9 storage system of Gal4 insertion where it was available was the "system stainless steel buffet server NP" was constructed by a consortium of Japan in the 1990s). By the way, I mean the "Nippon" that the NP is.
3. However, in search of "Enikaitamochi" command neurons, tool for ignite cells also did not have at the time of the first. It was intended stainless steel buffet server that "Enikaitamochi" command neurons exactly. It is necessary to inject the caged ATP per each individual for ATP channel 8) that were available at that time, it can not be very practical for screening. Led to the outbreak of light in mammalian genetics, and was able to get by with only one is after, it was the channel rhodopsin 2 which opens in response to blue light. An attempt was made to experiments with day in and day out channel rhodopsin 2, while it works very well in the larvae of Drosophila clear, even try to change no matter how much equipment and experimental conditions in adults is covered stainless steel buffet server with thick cuticle stainless steel buffet server brown I did not work. Some even tried to manufacture an experimental device that was referred to as "blue light arena" for viewing the action by applying a blue light in Drosophila, was that the behavior to expect, such as jump or paralysis occurs weak, but take action avoidance behavior to run around like crazy Drosophila gone hot and shed a strong light to take place, it did not to the level that can be applied to screening very common. Thus, in the place where you are at a loss, useful information was obtained. It's that likely activates the cells was introduced into Drosophila TRPM8 channel 10) that opens the cold genetically cloned from rat. Cells began to ignite on try Drosophila expressed the TRPM8 channel, lowering the temperature to 18 degrees, but since the cells become quietly desensitized immediately, and for use in behavior screening It was difficult. You can not afford to reduce to this temperature Drosophila wild type because stainless steel buffet server no work still result you still can not completely give up, I tried to condition setting finely define your own chamber that can control temperature accurately, and down to 14 degrees, but that little bit Only when it is maintained at between 16 Ueno 15 degrees, it was found that (for example, paralysis due to firing stainless steel buffet server of motor neurons) action by firing continues for a long time. Which requires a precise fine tuning of the temperature, stainless steel buffet server but the screening behavior is enabled summarize this. Summer of 2008, using an experimental apparatus including a chamber that is built using with the conditions set over time, and TRPM8, the male line 835 relatively few cells expressing Gal4 of lines of about 2000 NP line multiplied by the females expressed the channel, and observed the action is placed in a chamber which has been cooled to 15 degrees in advance of the F1. As a result, as expected, not only system that indicates the paralysis of 84 lines, lines 24 and even bounce fly, funny action came out in its own way, but there was no thing which I could use to experiment memory. However Luckily, around that time that screening by TRPM8 channel has been completed, this time, 11 TrpA1 channel that opens at high temperatures has been cloned gene from Drosophila). According to the paper, more of activation by TrpA1 channel seemed to be much more intense than TRPM8 channel. Therefore, the proboscis to no bait Multiplying the Drosophila expressing TrpA1 channel to the system of the NP system seen of any action by multiplying the Drosophila that express TRPM8 channel, system NP883 one raising the temperature of which the feeding behavior of licking the wall stretched repeatedly
