Psy 200 Lecture 4 Current LectureDouble 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 itis.-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 encodingMethod: 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