Model for Total Number of Synapses in a Human Brain

by Thai Nguyen

Submitted : Fall 2010

The brain is the organ that control all other organs and without a doubt, the most important organ in the human body. Just because it is the most important organ, doesn’t mean it is the most known about.  Some of the things we know about the human brain is that for being only about 5% of the total body weight, it uses 20% of the body oxygen (Gusnard, & Raichle, 2001). The cells in the brain are call neurons, and there is a consensus that there are roughly about 100 billion neurons total in the human brain. Each of these neurons can have up to 15,000 connections with other neurons via synapses (Understanding Brain Development in Young Children, 2005).  However, with that knowledge about the number of neurons and synapses, there is no model for the number of synapses as a function of time. A sample model can be generated using the studies by Bente Pakkenberg, on the degradation of neocortical neurons as a function of time and using the average number of synapses each neuron can form (Pakkenberg, & Gundersen, 1997). A hypothetical model for the number of synapses as a function of age for the life cycle of the human brain can be formulated. When comparing the two models, it shows that aging has more of an effect on the total number of synapses then total number of neurons.

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