![]() We are not aware of convincing estimates for synaptic density outside of the cerebral cortex, and our impression is that widely reported estimates of 10¹⁴ are derived from the assumption that the neocortex contains the great bulk of synapses in the brain. 3 This is roughly consistent with Eric Chudler’s summary of textbooks, which gives estimates between 0.6-2.4 x 10¹⁴ for the number of synapses in the cerebral cortex. According to stereologic studies that we have not investigated, there are around 1.4 x 10¹⁴ synapses in the neocortex. One way to estimate of the number of synapses in the brain is to extrapolate from the number in the neocortex. For instance reports 10¹⁴-10¹⁵ (100 – 1000 trillion) synapses in the brain, with no citation or explanation. Wikipedia says the brain contains 100 billion neurons, with 7,000 synaptic connections each, for 7 x 10¹⁴ synapses in total, but this seems possibly in error. The number of synapses in the brain is known much less precisely, but is probably about 10¹⁴. ![]() Eric Chudler has collected estimates from a range of textbooks, which estimate 1-2 x 10¹⁰ of these (10%-30%) are in the cerebral cortex. For instance, Azevado et al physically counted them and found 0.6-1 * 10¹¹. The number of neurons in the brain is about 10¹¹. Relevance of cells other than neurons to computations in the brain.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |