Most probably fewer than 100. Therefore, fewer than 100 neurons are needed to create a conscious entity. It sounds like a ridiculously small number. But our"conscious entity" is very different from humans. read more
For the definition that you probably have in mind about conscious entity, that of a well awakened individual permanently adapting his actions to the environment, a certain number of interconnected mental functions are necessary: reception of sensory information, codification into representations (many levels of treatment are necessary for them to become our thoughts), memory access, a pinch of emotion (the starter of the decision), and return of the action program to motor centers. read more
No, individual neurons are not conscious, but together they create consciousness. A neuron just does what it evolved to do. It has no mind of its own. It simply reacts to the external environment based off of evolved responses. read more