Brain complexity: roles of dopamine neurons (Introduction)

by David Turell , Friday, April 29, 2016, 02:08 (3131 days ago) @ David Turell

Spoken speech is considered to be left-sided in origin generally. but listened to speech is handled all over the brain:-"Previous neuroimaging studies of how the brain interprets speech have revealed a group of brain areas called the semantic system that appears to represent the meaning of language. Traditionally, these studies have focused on a single, narrow question or hypothesis about how the brain represents word or sentence meanings.-"To map the brain's semantic representation more broadly, study coauthor Jack Gallant of UC Berkeley and colleagues scanned the brains of seven graduate student volunteers while the study participants listened to more than two hours of stories from “The Moth Radio Hour.”-***
"Next, the researchers set out to determine what type of semantic information each part of the cortex represented. Because their data contained too many dimensions to feasibly model, the researchers used principle component analysis to home in on the three dimensions that preserve most of the information. They used these dimensions to tile the brains of each participant with color-coded semantic maps, in which different cortical regions corresponded to concepts such as people, places, or visual properties.-"Finally, Gallant's team developed a computational method to combine the maps of the different individuals to create a general semantic atlas. Despite some variation, the maps were surprisingly similar across individuals. This, the authors noted, may in part have been an effect of the small, somewhat homogeneous sample (graduate students at UC Berkeley).-***-"One of the more surprising findings was the functional symmetry between both brain hemispheres of the people studied, which appears to contradict decades of research on brain-injury patients suggesting a left-hemisphere bias in language processing. But most of these studies were focused on speech production, whereas the present study examined speech comprehension, Gallant told The Scientist."-Comment: Not surprising. Speaking involves the intent of one's organized thought. Listen requires understanding the words but also the underlying ideas behind what is heard