Psy 200 Lecture 4 Current Lecture Double dissociation requires two neural foci and two tasks Patient research or imaging One neural region is more involved in task A than B one region is more engaged in task A Lesion method has been the primary method for exploring mind brain relationships Limitations double dissociation is the exception not the rule Lesions are messy finding patients with right lesions can be difficult Brain functioning might change during recovery Neural Recordings Micro electrode implanted by axon detects action potential Benefits direct observation of single cells activity good temporal resolution you know where it is Limits you are putting an actual hole in the brain There are only a limited number of cells at once EEG electrode on scalp to measure brain activity non invasive Scalp electrode measure the summed electrical activity of synchronously active neurons ERP measuring EEG changes that one time locked to an event Electroencephalography EEG Spatial resolution is poor Can look at the changes in this signal as a function of mental activity Magnetic Resonance Imaging MRI Exploits magnetic properties of hydrogen atoms Proton in a hydrogen atom is in constant motion and creates small magnetic field Detectors in scanner measure these signals fMRI measures BOLD blood oxygen level dependent response Deoxygenated blood hemoglobin is paramagnetic Increase in neural activity leads to increase in blood flow to that tissue Tissue doesn t use all of increased blood leading to increase in ration of oxygenated blood to deoxygenated blood These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Spatial Resolution Voxels a small rectangular prism that is the basic unit of fMRI There are two hypotheses for why we forget things 1 Failure to retrieve we have the information we just can t find it 2 Failure of encoding Method Study a word list give recognition memory test BOLD signal time locked to stimulus onset during study phase fMRI Limitations temporal resolution is poor Visual Perception Object Recognition Receptive field The attributes of the world to which the cell responds Visual system was mapped by determining receptive fields of neurons Photoreceptors Rods sensitive to range of light intensities Contributes to brightness perception Cones need more incoming light and sensitive to different wavelengths of light Contributes to color perception