Here below is what Vivekananda tells about Kundalini in his book "Raja Yoga". He says: when we observe things, we memorise and store sensations about these things, and from this store we get dreams and imagination. But then he says that all this stored energy is Kundalini. I thought that Kundalini was something different.
Now, even after a long time I can remember the city. This memory is exactly the same phenomenon, only it is in a milder form. But whence is the action that sets up even the milder form of similar vibrations in the brain? Not certainly from the primary sensations. Therefore it must be that the sensations are coiled up somewhere, and they, by their acting, bring out the mild reaction which we call dream perception.
Now the centre where all these residual sensations are, as it were, stored up, is called the Mūlādhāra, the root receptacle, and the coiled-up energy of action is Kuṇḍalinī, "the coiled up". ... Now, if this coiled-up energy be roused and made active, and then consciously made to travel up the Suṣumnā canal, as it acts upon centre after centre, a tremendous reaction will set in. When a minute portion of energy travels along a nerve fibre and causes reaction from centres, the perception is either dream or imagination. But when by the power of long internal meditation the vast mass of energy stored up travels along the Suṣumnā, and strikes the centres, the reaction is tremendous, immensely superior to the reaction of dream or imagination, immensely more intense than the reaction of sense-perception. It is super-sensuous perception. And when it reaches the metropolis of all sensations, the brain, the whole brain, as it were, reacts, and the result is the full blaze of illumination, the perception of the Self.