Bracha over The Torah

Can you explain the different laws/Minhagim over reciting the Bracha when called to Torah. Should Sefer be open or closed, should one read the Bracha or say by heart?

In the Gemarrah (Megila 32a) there is a Tannic dispute whether when the Bracha before the Torah reading is recited the sefer should be open or rolled closed. The Gemarrah explains that the reason to close the Sefer is so that people would not think the Brachot are written in the Torah. The Halacha (Rambam, Shulchan Aruch) is that the Sefer is kept open (so that the Bracha will be followed (without a time gap) by the reading), since everyone knows the Brachot are not written inside. The Ramah, in a gloss, says the custom is for the Oleh to look aside when reciting the Bracha. Some people do close the Torah, since our Sifrei Torah are easily opened and shut, holding that the dispute was with Talmudic Sifrei Torah which were more unwieldy. The Mishna Brura quotes several Poskim who were opposed to the ruling of the Ramah (to look aside) since it indicates disrespect for the Sefer. Those who do look aside usually do so only slightly.