Functional Magnetic Resonance Imaging Lab Report

Functional magnetic resonance imaging (fMRI) is the scanning technique that examines the brain activity using the changes in the neuronal and cerebral blood flow. When haemoglobin is deoxygenated, it becomes paramagnetic (weakly attracted) and when it is oxygenated, it becomes diamagnetic (directed in 180 degrees towards magnet). Depending on the level of oxygenation, both of these slightly differ in magnetic resonance signal. Capillary red blood cells transfer oxygen to neurons, and when neurons require more oxygen, it increases blood flow, which increases neural activity, this is known as BOLD fMRI. In MRIs, the magnetic nuclei of atoms reacts to the magnetic field of the scanner, therefore nuclei align with the direction of the magnetic

Richard Caton (1842-1926) invoked the idea of potential “feeble currents of varying direction pass through the multiplier when the electrodes are placed on two points of the external surface.” ERP is measured with an EEG (electroencephalogram) which measures voltages in brain structure, however EEG is response to sensory, motor and cognitive whilst ERP is response to an event. Electrodes are places on the scalp of the individual and electrical activity in the brain is measures, picking up thousands of brain processes simultaneously shown in. An ERP is shown in a wave pattern on a computer screen or paper, wavelengths depend on the activity of the brain. However, to examine the individual’s response to the actual event, they must partake in many trials to gain validity. ERP can measure mental illnesses differing from dementia, OCD, MS, Parkinson’s and stroke. Martin Eimer conducted research on transient and sustained non-spatial visual attention to colour and form using an ERP. It was found that both the transient (to be attended feature) and the sustained (constant for entire experimental block) has a higher negativity for attended than unattended by 200 – 300 ms after the stimulus was exposed. It was also found that their was more attention towards the colour rather than directed to the form. Participants were told to attend to a specific stimuli, whether colour or form, whilst an behavioural parameters and ERP were used the to be attended stimuli and electrophysiological measures were used for irrelevant features and stimulus. J. Townsend, M. Westerfield, E. Leaver, S. Makeig, T. Ping Jung, K. Pierce and E. Courchesne all conducted research on the ERP reponse to autism abnormalities, examining the cerebello frontal spatial attention networks. In the spatial processing, they found abnormalities which were generated in two components of the late positive