SuttaCentral
This is exactly what happens at the path moment.
Let’s use our modern neuroscience terminology of neuroplasticity.
Neuroplasticity is happening all the time, in particular at night.
In a path moment (there could be several of these moments for a particular Stage) the brain reorganisation is sudden and dramatic (i.e. extensive (depending on which group of fetters are destroyed) and with no going back (a characteristic that I have not heard of in neuroscience)).
The Mirror of the Dhamma
“But truly, Ananda, it is nothing strange that human beings should die. But if each time it happens you should come to the Tathagata and ask about them in this manner, indeed it would be troublesome to him. Therefore, Ananda, I will give you the teaching called the Mirror of the Dhamma, possessing which the noble disciple, should he so desire, can declare of himself: ‘There is no more rebirth for me in hell, nor as an animal or ghost, nor in any realm of woe. A stream-enterer am I, safe from falling into the states of misery, assured am I and bound for Enlightenment.’”
"And what, Ananda, is that teaching called the Mirror of Dhamma, possessing which the noble disciple may thus declare of himself…? DN16
There are several version of this Mirror of the dhamma (see the Stream entry study guide at accesstoinsight). It is a list of character attributes and insights which allow a person to self-evaluate their attainment (with some degree of accuracy, not 100% of course) unless each of the pali terms can be properly subjected to study.
These characteristics are the cause of the attainment, in terms of the gradual path, rather than the result. The path is described as ‘gradual incline, sudden deepening’, the latter being the attainment and the former being the gradual practice. We know that personalities change regardless over time and are not fixed like previously thought. Add intention to practice and change and the brain networks will rewire, over time. Its difficult to say what the fMRI will look like when the mind hits nibbbana for a moment.
with metta
Thank you Matt very useful.