REVIEW SHEET: EXAM 2 1 METHODS IN COGNITIVE NEUROSCIENCE On the exam, you will be asked to make decisions about which of the methods listed below would be the best for a particular research question (i.e., if you were researching a particular question which method would be best suited to answering that research question?). You can answer that type of question by knowing the STRENGTHS and WEAKNESSES of each method. The STRENGTHS and WEAKNESSES have a lot to do with whether the measure is direct or indirect, whether it is invasive or noninvasive, what its spatial and temporal resolution are, and whether it provides causation or correlation. So, if you can answer the following questions about each method then you should be able to do well on that part of the exam: 1. WHAT particular aspect of brain function it is MEASURING (e.g., extracellular ionic current? post-synaptic potentials? blood flow?) 2. WHAT kind of POPULATION the method can most easily be used with (e.g., animals, humans, both?) 3. WHAT is the range and maximum TEMPORAL resolution? (if it is a Functional Method) 4. WHAT is the range and maximum SPATIAL resolution? (if it is either a Functional or Structural Method) 5. Can it provide information about CAUSATION (i.e., that a brain area CAUSES a cognitive process) or just show a CORRELATION between brain and cognitive process? In addition, you should be able to answer these specific questions about each method: Invasive, Direct Methods of measuring Function Noninvasive methods: Structural and Functional Single-unit/Multi-unit recording in animals and neurosurgical patients • Why is it important to have both an experimental condition and a control condition? • When might activity in a single cell serve as a useful measure of a cognitive function? • What is the difference between a local representation (grandmother cell) and a distributed representation? Functional Methods: EEG, ERP, MEG (Direct Measures) • Why are these measures (EEG/ERP/MEG) viewed as more “directly” measuring brain activity than fMRI or PET? • ERP: What does averaging do to the “signal” in EEG vs. the “noise”? • What is the difference between an exogenous and endogenous ERP? • What is the difference between EEG and MEG? • What is mental chronometry and why are these methods good for measuring it? • What is the inverse problem and how does it affect the spatial resolution of these methods? Functional Methods: fMRI, PET (Indirect Measures) • What is “The Engine Metaphor” of Functional Metabolic Imaging and how does it relate to PET and fMRI? • What is one good reason a researcher still might use PET today, now that fMRI is readily available? • What is the Subtraction Method used in many types of functional imaging? How is it controlling for spontaneous background activity? What is the problem of pure insertion that could make this method invalid? • What is the Conjunction analysis approach? Parametric Variation analysis approach? (also see text) Lesions: Naturally-occurring lesions in humans and Transcranial Magnetic Stimulation (TMS) • Why is it important to look both at impaired and spared behaviors following lesions? • What is the difference between a case study and a group study? Which is better for partitioning cognitive functions; for establishing lesion-deficit associations? • What is the assumption of transparency and why is diaschsis a problem for this assumption? • In group studies, patients can be grouped by lesion, by symptom or by syndrome; be able to differentiate which is the IV and which is the DV in each situation. • What is the difference between a single and a double dissociation? What is task-resource artifact and why is a single dissociation more vulnerable to this than a double dissociation? • What are the strengths and weaknesses of using TMS (virtual lesions) compared to naturally occurring lesions (or induced lesions in animals)? In TMS studies, what is the IV and what is the DV? Structural Methods • How can structural methods be used to provide information about brain-behavior relationships? • What is co-registration?REVIEW SHEET: EXAM 2 2 AUDITORY SENSATION AND PERCEPTION Define FREQUENCY/PITCH, AMPLITUDE/LOUDNESS AND COMPLEXITY/TIMBRE in terms of how each of these relate to different “aspects” of soundwaves (i.e., number of molecules, speed of compression and rarefaction, etc). • What is the fundamental frequency? Be able to describe the process by which soundwaves are conducted from the outside world into the cochlea, and ultimately transduced into neural signal, highlighting the roles of the: • Tympanic Membrane (eardrum) in the Outer ear • Bones of the Middle ear • Cochlea in the Inner ear (Hair cells, Basilar and Tectorial Membrane) • Spiral ganglion cells Auditory Pathway to Cortex (from PNS to CNS) • Consider similarities/differences from visual pathway in terms of relay points…(inferior/superior colliculus; medial/lateral geniculate nucleus) and dorsal/ventral stream? • How do the “core” and the “belt” of A1 differ from each other in terms of the types of sounds they respond to? • What are the contributions of the left and right hemisphere to: speech perception; music perception Coding “What”: the Pitch (Frequency) and Loudness of incoming sounds • How are high and low frequency pitches coded (tonotopically) in the…Cochlea? A1? Coding “Where”: Localizing sound § What are Interaural level differences vs. Interaural time differences? § What is the head-related transfer function? § Place-specific cells in auditory cortex; understand which is better for detection vs. discrimination: broad vs. narrowly tuned cells? § Do we use visual information to localize sound? What is the McGurk Illusion? VISUAL SENSATION AND PERCEPTION Know how the TWO VISUAL FIELDS are processed in the PNS (retina: binocular vs. monocular vision) and in the CNS (after the optic chiasm) • What does it mean to describe the visual system as retinotopically organized? Know something about the STRUCTURE AND FUNCTION of cells in the RETINA • What types of cells are found in the three main layers of the retina? • What is the direction of light through the retinal layers? What is direction of the neural signal? • What is the importance of the cells that connect “within” layers (amacrine and horizontal cells)? •