Nerve cells are unable to divide because they lack centrioles, which plays important role in cell division. Centrioles help to arrange the microtubules that move chromosomes during cell division to ensure each daughter cell receives the appropriate number of chromosomes. While all other cells in our body have capacity to regenerate/self-repair. Related Theory Our brain is evolved to process complex tasks at a higher pace than other living beings. The brain achieves this with help of the whole nervous system, which is based on interneuronal connections, so adding an extra neuron would mess up these connections and alter both the functionality and the "stored" information. New cells in the nervous system wouldn't do any good. Thus, we lack of regenerative capacity of neurons.