Localization of Brain Function

Early Research into Brain Localization Paul Broca, 1861: left Frontal lobe area—understand and make correct grammatical sentences (“Broca’s aphasia” is the inability to do this) Carl Wernicke, 1874: left posterior Temporal gyrus—produce intelligible speech (“Wernicke’s aphasia is the inability to do this) Both Broca and Wernicke based their information on postmortem studies of afflicted patients, not living brains

Kim and Hirsch, 1997: Language Processing in Bilingual Patients Aim: use an fMRI to study brain processing in bilinguals Method: Group 1: learned 2nd language as kids; Group 2: learned 2nd language as adults; both groups were asked to think about events in both languages sequentially

Results: Both groups used same parts of Wernicke’s area regardless of which language was being engaged; Group 1 used the same region of Broca’s area for both languages, but Group 2 used Broca’s area along with adjacent regions for the 2nd language Discussion: increased knowledge of localization and also integration of the brain with regards to language, spurred further research into other areas of integration

Ethics in Research on Brain Localization Nucleus Accumbens (NAcc) = the brain’s pleasure center Heath, 1950’s: studied patients that could voluntarily stimulate their NAcc; one subject recorded 1,500 stimulations in 3 hours Olds, 1950’s: rats would willingly cross an electrified field to press a bar that would stimulate the NAcc to the point of severe burns on their feet

The NAcc relies on Dopamine and Serotonin; behaviors that utilize these neurotransmitters result in the increase of their production in this region of the brain, thus over-riding the Frontal lobe’s ability to regulate their effects (e.g. addiction)

Technology in Brain Research Invasive techniques: Lesioning Lobotomies Hemisphrectomies 1942: Hetherington and Ranson—lesioned the Ventromedial Hypothalamus in rats resulting in obesity due to the inability to regulate hunger (ethics: trauma, pain, irreversible)

Electroencephalogram EEG: registers patterns of voltage change in the brain; studies of sleep, emotion and epilepsy

Functional Magnetic Resonance Imaging (fMRI) fMRI: 3D pictures using magnetic fields and radio waves, shows brain areas that are active during functioning

Positron Emission Tomography (PET) PET scan: monitors glucose metabolism, used for tumors, Alzheimer’s, neural disorders and possibly gender differences in brain activity

PET Scan: ADHD

PET Scan: Alzheimer’s

PET Scan: Schizophrenia