It depends on what you consider "true artificial intelligence". But this probably means to be able to think like a human - and perhaps, do so in a more rational manner, as in the human brain emotion comes before ratio.
It would seem that a neural network, or a genetic algorithm that evolves neural networks, is the closest way - mimicking humans.
However, the traditional counter-argument to this is that we tried to do the same with flight. We tried to copy nature, mimick the birds - trying to fly by flapping wings. But eventually we made airplanes that did not rely on flapping their wings.
In AI, there are far more variables than in aerodynamics. So it is quite likely that a human-like intelligence can be attained by other methods than neural networks.
In the end, neural networks are one approach to machine learning. There are others, all governed by the rules for what can and cannot be learnt. (There is a field called Computational Learning Theory that covers this).
Although it is possible to extend learning systems beyond what can be learnt according to COLT, this means that such a learning system - neural network or otherwise - is essentially flawed, and will draw wrong conclusions at one point or another.