TAILIEUCHUNG - Theory of Brain Function quantum mechanics and superstrings - part 5

Vì vậy, chúng ta hãy tập trung vào cấu trúc chi tiết của các tấn thần kinh. Mỗi tế bào thần kinh cá nhân, như là một tế bào eucaryotic, có cytosceleton của nó. Do không may cho chúng ta, thực tế rằng các tế bào thần kinh không nhân sau khi não được hình thành đầy đủ, có vẻ là không có vai trò đối với một centriole trong các tế bào thần kinh | 37 So let us concentrate now on the detailed structure of the neural MTs. Each individual neuron as being an eucaryotic cell has its cytosceleton. Due to the unfortunate for us fact that neurons do not multiply after the brain is fully formed there seems to be no role for a centriole in the neural cell. Indeed centrioles seem to be absent in the neuron s centrosome which as usual is found close to the neuron s nucleus. Neural MTs can be very long indeed in comparison with their diameter of order of O 10nm and can reach lengths of mms or more There are about 450 MTs 2 or about 7 X 105 tubulins 3 along the neural axon. Furthermore as we mentioned above the potential computing brain power increases substantially if the tubulin dimers of characteristic two-state conformational frequency of 101oHz are taken to be the basic computational units. Indeed in the case of the neuron unit we get something like 1014 basic operations per sec 1011 neurons x 103 signals neuron sec while in the case of the tubulin dimer unit we get something like 1028 basic operations per sec 1011 neurons x 107 tubulin neuron x 1010 signals tubulin sec A rather remarkable gain on brain power by replacing neuron-type switches with microtubular information processors even if we reduce it for efficiency nonparticipation etc. down to say 1025 bits . The neural MTs can grow or shrink depending on the circumstances they transport neurotransmitter molecules they are running along the lengths of the axons and dendrites and they do form communicating networks by means of the connecting MAPs. Neural MTs seem to be responsible for maintaining the synaptic strengths while they are able to effect strength-alterations when needed. It also seems that neural MTs play a fundamental role in organizing the growth of new nerve endings piloting them towards their connections with other neuron thus contributing or being mainly responsible for the formation of neural networks in vivo. Neural MTs extend from the centrosome

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