Is the Brain a Computer?

Alan Forrester¹ says ‘no’, the brain is not a quantum computer but a classical one:

Quantum mechanics has almost no bearing on the operation of the brain, except insofar as it explains the existence of matter. You say that signals are carried by electrons, but this is very imprecise. Rather, they are carried by various kinds of chemical signals, including ions. Those signals are released into a warm environment that they interact with over a very short timescale.

Quantum mechanical processes like interference and entanglement only continue to show effects that differ from classical physics when the relevant information does not leak into the environment. This issue has been explained [in] the context of the brain by Max Tegmark in The importance of quantum decoherence in brain processes. In the brain, the leaking of information should take place over a time of the order 10⁻¹³ − 10⁻²⁰ s. The timescale over which neurons fire etc. is 0.001 − 0.1s. So your thoughts are not quantum computations or anything like that. The brain is a classical computer.