Wherever the Torah refers to thinking and feelings of Anger, compassion etc. it always mentions the Heart as the controlling organ (also Kidney) but NEVER the Brain? (Even in the G'mara the Moach is rarely mentioned).
The word מוח only turns up once in Tanakh anyway (Job 21:24). It means "marrow". Onkelos translates קדקוד in Deut 28:35 as מוח, and we see it with a similar meaning ("brain", and the membrane around the brain) in the early rabbinic literature. The fact that it's not mentioned in the Tanakh can be due to their either having a different word for the same thing, or to the fact that it's a part of the body that they never speak about. Either way, they did not consider it the seat of thought.
The first person in recorded history to recognise the brain as the source of thought and understanding was Alcmaeon of Croton, a Greek philosopher and physician who lived in the 5th century BCE.
In reality, I personally don't think that this is a question at all: everyone from the Torah's time period believed in the heart as the source of emotions, so this is how the Torah was written. However, I'm happy to provide a source to this effect.
This issue has indeed been noticed by many people, among them R. Shlomo Fisher, who many would consider to be among the generation's foremost Torah scholars, especially in matters pertaining to theology. He brings up this question in his major work, Beis Yishai (Drashos, pg. 361 n. 4).
First of all, just to help a bit, he says that the Gemara does hint to the fact that the brain was the seat of thought, in Yevamos 9a and Menachos 80b, where someone is derided with the phrase 'it appears that he has no brain (מוח just means soft material) in his skull'. He admits, however, that there are many other instances in Shas where it appears that the Sages believed otherwise.
Second, he says that the fact that the Torah never mentions the brain is totally besides the point, as all of the Medieval sages understood that the "the Torah speaks in the language of man", which means, specifically, in the language of the first generation to receive the Torah - and they never knew of the brain's actual function. God first used the Torah to communicate with the generation which received it.
However, he thinks that the fact that the Torah does refer to the heart as the seat of thought/emotion is actually a problem, because the Torah would never promulgate falsehoods, even if they were to have been accepted by everyone in the generation. He then that every prophet received a prophecy that they interpreted according to how they understood the universe. Therefore, even if God may have been giving them a true message, they will interpret it according to their own scientific understanding. Thus, Maimonides insists upon explaining the vision of Ezekiel according to a picture of astronomy that he himself thought to be false, because Ezekiel thought it to be true.
While he doesn't add this caveat, I don't think that R. Shlomo Fisher would say the same thing regarding the prophecy of Moses and the Torah. (Though it would appear that this inaccuracy of referring to the heart as a source for thoughts appears there too) Instead, the second point is probably more accurate: that God gave messages using the common idiom, which was to refer to thoughts as originating in the heart.
The Vilna Gaon on Yona says:
Later on he adds:
Later, on Yona 4:11, the Gaon comments:
So it seems thought can arise in the mind but the heart is the one who decides/rules what to do therefore it is considered the real thinker
In Tanakh, dreams appear in association with what occurs in the head (mind). When Jacob dreamed, the angels descended upon and ascended from his head. When Joseph understood the dreams of the cupbearer and baker of Pharaoh, the interpretation had to do with their heads. (His earlier dreams had to do with his own headship among his family and father, Jacob.) When Daniel later interpreted the dreams of Nebuchadnezzar, the meaning had to do with the head of Nebuchadnezzar. Tanakh then appears to correlate the head with the mind in these instances, if we assume a priori that dreams are thoughts.
The Talmud also mentions one instance of the head bearing on dreams in this regard -