COGNITIVE NEUROSCIENCE

Transcription

1 HOW TO STUDY MORE EFFECTIVELY (P ) Elaborate Think about the meaning of the information that you are learning Relate to what you already know Associate: link information together Generate and test yourself Active involvement with the information Come up with your own questions and then answer them Organize Create (generate!) outlines to form a framework to connect information (elaboration!) Chunking: group information together Take breaks Use distributed practice (with breaks) instead of massed practice (aka cramming) Sleep to allow for memory consolidation (p16) Match learning and testing conditions Study same place as test OR study in many different locations Avoid illusions of learning Don t mistake ease and familiarity with knowing (in preface of textbook) 2 COGNITIVE NEUROSCIENCE Chapter 2 1

2 LEARNING OBJECTIVE TOPICS Microstructure of the brain: Neurons Structure and communication Cognitive Neuroscience Approaches Neuropsychological Neurophysiological Computational 3 UNDERLYING STRUCTURE Neurons and action potentials 4 2

3 NEUROPHYSIOLOGICAL RECORDING Single cell recording Record action potentials from single neurons 5 DELAY NON-MATCH TO SAMPLE TASK CUE CHOICE 6 3

4 SINGLE UNIT RECORDING Unit recording in nonhumans; direct measurement of neuronal activity Measurements from two frontal-lobe neurons during delayed non-matchto-sample task 7 Single Unit Recording Cell A responds to a particular stimulus during the cue & choice periods 8 4

5 SINGLE UNIT RECORDING Cell B shows sustained activity during the delay ( memory cell) 9 LEARNING OBJECTIVE TOPICS Microstructure of the brain: Neurons Structure and communication Cognitive Neuroscience Approaches Neuropsychological Neurophysiological Computational 10 5

6 OVERVIEW OF APPROACHES Neuropsychological - patient studies - lesions in nonhuman animals - transcranial magnetic stimulation Neurophysiological - neuroimaging (PET, fmri, ERP) - unit recordings in nonhuman animals Computational - computer modeling, simulation, prediction 11 LESIONS What is a lesion? What can it tell us? 12 6

7 NEUROPSYCHOLOGICAL APPROACH Logic: If a region of the brain is essential for some aspect of memory, Then damage to that region should affect performance on that aspect of memory ** So neuropsychological approaches can tell us about the NECESSITY of a region for a particular function 13 TYPES OF LESIONS Non-human animals Human animals Temporary Lesions: TMS Pros and cons? 14 7

8 H.M. 15 BRAIN LESION STUDIES Artist Anton Raederscheidt s self-portrait painted at different times following a severe stroke which left him with neglect of contra-lesional space 16 8

9 BRAIN LESIONS IN MOUSE 17 TRANSCRANIAL MAGNETIC STIMULATION clip 18 9

10 TMS VIDEO 19 NEURAL NETWORKS Brain areas do not act in isolation! 20 10

11 OVERVIEW OF APPROACHES Neuropsychological - patient studies - lesions in nonhuman animals - transcranial magnetic stimulation Neurophysiological - neuroimaging (PET, fmri, ERP) - unit recordings in nonhuman animals Computational - computer modeling, simulation, prediction 21 (F)MRI: (FUNCTIONAL) MAGNETIC RESONANCE IMAGING 22 11

12 Functional Magnetic Resonance Imaging (fmri) Measures blood flow through magnetic properties of blood 23 functional MRI! (Magnetic Resonance Imaging)! Can use a blocked design (figure out the blood flow response associated with each 30-sec period) 24 12

13 functional MRI! (Magnetic Resonance Imaging)! 25 event-related design: measure blood flow response associated for individual trials, rather than for a block of trials EVENT-RELATED DESIGNS Minimize state effects Permit analysis based on subject s behavior Provide an index of the task elicited hemodynamic response BUT Limited temporal information 26 13

14 SUBTRACTIVE LOGIC Most of the brain is active during most events We want to isolate regions that are specific to a task So, construct 2 conditions that you believe have just some crucial interesting difference Treat one as baseline and subtract it from the other, to get rid of all the activity the 2 conditions have in common 27 Subtractive Logic! " rest read rest remember rest read rest remember - rest = all regions active in remember condition NOT rest (could be difs. Due to reading words OR processing word meaning OR in trying to remember words) remember - read = all regions active in remembering words (but controlls for processing of word meaning and word reading) 28 14

15 New New 30 15

16 Old

17 THE BASELINE IS EXTREMELY IMPORTANT!!! Peterson, Fox, Posner, Mintun & Raichle (1988) Research question: What is the brain activity associated with. Recognizing written words? Saying words? Retrieving the meaning of the words? 33 METHOD: RECOGNIZING WORDS Experimental: Passive Viewing of Words Ex. See CAKE Baseline: Passive viewing of fixation cross (+) METHOD: SAYING WORDS Experimental: Read aloud a written word Ex. See CAKE, say Cake Baseline: Passive Viewing of Words Ex. See CAKE METHOD: RETRIEVING MEANING Experimental: Generate an action Ex. See CAKE, say eat Baseline: Read aloud a written word Ex. See CAKE, say Cake 34 17

18 PROBLEMS WITH THE BASELINES? What could be the problem with comparing passive viewing of words vs. a fixation cross (+)? We assume: Pure Insertion adding an extra component does not affect the operation of earlier ones in the sequence 35 PROBLEMS WITH THE BASELINES? What are we doing during fixation? The default network Holland & Kensinger (2013) Experimental Task: Recall Autobiographical Memories Baseline Task: Fixation Cross (+) What would be a better baseline? 36 18

19 STROOP EFFECT AND THE BRAIN Stroop effect measures: Interference: slower process vs. faster process Selective attention Area often associated with Stroop: Anterior cingulate cortex (ACC) Hypotheses for function of area: Allocate attentional resources when there is competing information Used to mediate response selection Resolving response competition BUSH ET AL., 1999: STROOP AND FMRI Anterior Cingulate Activity No Anterior Cingulate Activity Knowing the Stroop, what was the subtraction that they likely did? What do you predict the ADHD results were on the Stroop? Is it important that they do this as an event-related design or could they do blocked? 38 19

20 NETWORKS! FUNCTIONAL CONNECTIVITY 39 PET! (Positron Emission Tomography)" Measure blood flow in a different way" Small dose of a chemical (radionuclide) used to label glucose is injected into patient. " The radionuclide emits positrons. " A PET scanner will rotate around a patient's head to detect the positron emissions given off by the radionuclide. " 40 20

21 PET! (Positron Emission Tomography)! " resting in scanner (no task) 41 PET! (Positron Emission Tomography)! " reading words 42 21

22 PET! (Positron Emission Tomography)! " trying to remember words for a later memory test 43 PET! (Positron Emission Tomography)! " must perform tasks in blocks of at least 30 sec rest read rest remember rest read rest cannot sort by performance (e.g., words that are later remembered vs. words that are later forgotten) 44 22

23 CARTER ET AL., 1997: PET, STROOP, SCHIZOPHRENIA People with Schizophrenia have less ACC activity during the Stroop 45 METHOD: EVENT-RELATED POTENTIAL (ERP) Neuron firing is an electrical event Measure electrical activity on the scalp and make inferences about underlying brain activity Averaged over a large number of trials to calculate ERPs Advantage: continuous and rapid measurements Disadvantage: does not give precise location 23

24 ERP: EVENT-RELATED POTENTIALS 47 ERP: EVENT-RELATED POTENTIALS 48 24

25 BERTSCH, BOHNKE, KRUK & NEUMANN (2009): STROOP & ERP Provoked Aggression in participants Did Emotional Stroop Looked for specific waveforms P2 ( ms) P3 ( ms) Have been associated with early and late stages of processing emotional information P2 Waveform ( ms) 50 25

26 P3 Waveform ( ms) 51 WHAT DOES THIS TELL US ABOUT EMOTION PROCESSING AND AGGRESSION? 52 26

27 PROS AND CONS OF METHODS ERP Pro: time-course of response Con: only estimate of location PET/fMRI Pro: localize functions to structures in brain Con: lack knowledge of circuit In general: Pro: knowledge of areas of brain activated for cognitive processes Con: subtraction technique; interpretation of findings OVERVIEW OF APPROACHES Neuropsychological - patient studies - lesions in nonhuman animals - transcranial magnetic stimulation Neurophysiological - neuroimaging (PET, fmri, ERP) - unit recordings in nonhuman animals Computational - computer modeling, simulation, prediction 54 27

28 COMPUTATIONAL NEUROSCIENCE Mathematical models of systems in neuroscience From ion channel biophysics through whole brain simulations Constrained by experimental results and makes predictions on future studies 55 GROUP ACTIVITY Hypothesis: The ability to learn people s names (i.e., face-name pair learning) is dependent on the hippocampus What technique would be best to test this hypothesis? (behavioral study? Neuroimaging? Lesion studies? Other methods?) What result would support this hypothesis? Reject it? What factors would you need to control for to be certain that it was the learning of the names, in particular, that was dependent on the hippocampus? 56 28

29 Hypothesis: Orbitofrontal cortex is not critical for learning face-name pairs. Hypothesis: The ability to learn face-name pairs is impaired in older adults Hypothesis: Learning face-name pairs is helped by deliberative attempts to connect the names to the faces