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Cognitive Neuroscience NEUR 3860 Review Session October 19, 2009 Megan Metzler

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Presentation on theme: "Cognitive Neuroscience NEUR 3860 Review Session October 19, 2009 Megan Metzler"— Presentation transcript:

1 Cognitive Neuroscience NEUR 3860 Review Session October 19, 2009 Megan Metzler

2 Outline History of neuroscience Techniques of cognitive neuroscience Vision

3 History of Neuroscience TIMELINE 1600s Scientific Revolution Dualism vs. Monistic Materialism Late 1700s to early 1800s Phrenology vs. Aggregate Field Theory Late 1800s to early 1900s Darwinism Lesion studies (Broca & Wernicke) Neuron hypothesis Cytoarchitectonics

4 History of Neuroscience Scientific Revolution Dualism vs. Monism Rene Descartes, Galileo ScholasticismEmpiricism authoritydirect observation (falsifiability, mathematical measurement, peer review, skepticism, parsimony) animismmechanism Cartesian DualismMonism Separation between mechanistic and conscious processes Experience= Brain Function= Consciousness Forms of same argument persist today: e.g. predicate dualism, property dualism Sutherland’s 2 sides of the same coin analogy

5 History of Neuroscience Phrenology- organization of the brain around ≥ 35 functions – Franz Joseph Gall & J. C. Spurzheim – Surface of the skull revealed relative use of the functional area underneath it; size is use- dependent Aggregate Field Theory- the whole brain determines the whole of behaviour – Marie-Jean-Pierre Flourens found that regardless of where a bird’s brain was lesioned, it recovered.

6 History of Neuroscience Darwinism Natural selection- favorable, inheritable traits spread in a population Supports Monism Comparative study between humans and other organisms feasible Processes may be adaptive (over geological time) By extension supports Functional Design – “Mechanism” transforms “target” system to create a “desired state”

7 History of Neuroscience Lesion Studies Broca Wernicke Neuron Hypothesis Golgi invented the silver stain Ramon y Cajal used the stain to differentiate individual neurons

8 History of Neuroscience Cytoarchitectonics Cellular architecture Brodmann- organized cortex into 52 regions based on neuronal differences highlighted by staining

9 History of Neuroscience QUESTIONS Short Answer: 1.The view that those in authority are the best source of knowledge is called ____________. 2.Darwin’s theory of evolution assumes that mechanistic processes are solely responsible for the development of all species, consequently supporting ___________ while disputing dualism. 3.The view that the whole brain participates in behaviour is called _____________ theory. 4.Brodmann developed a _______________ map using the method of _________ ___________.

10 History of Neuroscience QUESTIONS Short Answer: 1.The view that those in authority are the best source of knowledge is called Scholasticism. 2.Darwin’s theory of evolution assumes that mechanistic processes are solely responsible for the development of all species, consequently supporting Monism while disputing dualism. 3.The view that the whole brain participates in behaviour is called Aggregate Field theory. 4.Brodmann developed a cytoarchitechtonic map using the method of tissue staining.

11 History of Neuroscience QUESTIONS Multiple Choice: 5.According to Cartesian dualism a) The processes that underlie consciousness are mechanistic. b) Human consciousness cannot be understood by mechanistic processes because it is not mechanistic. c) Spirit-like and mechanistic properties coexist in all matter. d) Empirical and authoritative perspectives are complementary.

12 History of Neuroscience QUESTIONS Multiple Choice: 5.According to Cartesian dualism a) The processes that underlie consciousness are mechanistic. b) Human consciousness cannot be understood by mechanistic processes because it is not mechanistic. c) Spirit-like and mechanistic properties coexist in all matter. d) Empirical and authoritative perspectives are complementary.

13 History of Neuroscience QUESTIONS 6.The most significant contribution to neurology in the 19 th century was: a) Phrenology and resultant methods to identify varying development of specific cognitive abilities across individuals. b) Animal research with pigeons which studied the behavioural effects of localized lesions. c) Use of the “the black reaction” to differentiate individual neurons. d) Detailed anatomical drawings of the human brain.

14 History of Neuroscience QUESTIONS 6.The most significant contribution to neurology in the 19 th century was: a) Phrenology and resultant methods to identify varying development of specific cognitive abilities across individuals. b) Animal research with pigeons which studied the behavioural effects of localized lesions. c) Use of the “the black reaction” to differentiate individual neurons. d) Detailed anatomical drawings of the human brain.

15 Techniques of Cognitive Neuroscience Cellular Connectivity Tracers Diffusion Tensor Imaging Structural and Functional Imaging Magnetic Resonance Imaging Functional MRI Positron Emission Tomography Electrophysiology Intracranial Cell Recording Electroencephalography Magnetoencephalography Lesion studies

16 Cellular Connectivity General Principles High degree of interconnections in the brain which is likely responsible for cognition Prime example: in the visual system there is estimated to be 10 descending projections for each ascending projection  also highlights the limitations associated with structural assessment techniques

17 Cellular Connectivity Tracers Provide clues to connectivity at the cellular level – Brodmann map reflects function Retrograde tracers – e.g. horseradish peroxidase Anterograde tracers

18 Cellular Connectivity Diffusion Tensor Imaging Uses MRI to trace long white matter tracts – Takes advantage of how water movement is restricted within axons – Identifies the movement of protons between magnetic pulses and identifies non-random patterns

19 Structural and Functional Imaging General Principles Importance of co-registering structural and functional images – Resolution of structural techniques combined with change detected by functional technique Functional images relay information about electric fields, magnetic fields, oxygenated blood Correlation does not determine causation Common language of describing location in the brain – Reported as voxels (volumes, slices, pixels) – Talairach Coordinate System – Montreal Neurological Institute (MNI) Template – MNI “Representative” Brain

20 Structural and Functional Imaging Magnetic Resonance Imaging (MRI) Uses magnetic energy to move protons in hydrogen atoms into alignment with the magnet. Radio waves nudge the protons out of alignment (property called nuclear magnetic resonance). When the radio waves stop, the protons move back to their original position, releasing energy which is measured Resolution= 1 mm 3

21 Structural and Functional Imaging functional MRI Blood oxygenation level-dependent (BOLD) effect: change in the ratio of oxygenated to deoxygenated hemoglobin Resolution= 3mm 3 Positron Emission Tomography (PET) Inject a radioisotope (usually of oxygen) and monitor concentration of decaying tracer (gives off gamma rays in a predictable pattern) Resolution of 5-10 mm 3

22 Functional Imaging Study Design Blocked design- alternates between rest and active conditions

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24 Electrophysiology General Principle Based on the principle that neurons exhibit graded potentials and action potentials Intracranial Cell Recording Use single or multiple electrodes to measure action potentials from a single neuron or a population of neurons. Raw data depicted as a “spike train.”

25 Electrophysiology Methods Intracranial electrodes Subdural grid Electroencephalography Magnetoencephalography (related but not technically measuring electrical fields)

26 Electroencephalography The field generated by a patch of cortex can be modeled as a single equivalent dipolar current source with some orientation (assumed to be perpendicular to cortical surface) (This should look familiar)

27 Magnetoencephalography For any electric current, there is an associated magnetic field magnetic sensors called “SQuID”s can measure very small fields associated with current flowing through extracellular space Magnetic Field Electric Current SQuID Amplifier (This should look familiar)

28 Electrophysiology Study Design Event Related Potential (ERP)

29 Electrophysiology Localization Few methods that apply to EEG and MEG – Plot oscillations across sensors as a 2D map, called an isopotential map – Brain Electrical Source Analysis Identify 3D generator source through modelling neural activity as one or more equivalent current dipoles – Beamforming Signal processing technique that adjusts the signal recorded at each sensor to tune the array to a single voxel at a time – Possible to coregister with structural image (MRI)

30 Lesion Studies Methods- Animals – Aspiration – Electrolytic – Vascular lesions (e.g. endothelin 1- stroke) – Reversible – Selective pathways (e.g. MPTP- Parkinsons) – Transgenic animals (Gene knock-Out, Knock-In) Selectively block specific receptors ASSUMES that behavioural change after a lesion reveals function of the damaged area. – Issue of interconnectivity

31 Lesion Studies Methods- Humans – Ischemic/Hemorrhagic Stroke – Trauma – Surgery – Reversible Lesion Transcranial Magnetic Stimulation

32 Lesion Studies Study Design Double Dissociation – Single dissociation may be due to the different sensitivities of the two tasks – Allows demonstration that the damaged area contributes to the task in some way (cannot state that the area is responsible) Speech Output ScoreVerbal Compre- hension Task Left inferior frontal lobe damage (Broca’s)  Controls  Left posterior parietal lobe damage (Wernicke’s) 

33 Techniques of Cognitive Neuroscience

34 Techniques of Cognitive Neuroscience QUESTIONS Multiple Choice: 1. You plan to write a study proposal for a project that hypothesizes a positive relationship between connectivity of the prefrontal lobe and visual cortex and success in complex spatial tasks. What is the best technique to apply to your particular research hypothesis? a) Diffusion Tensor Imaging and a measure of spatial ability b) fMRI and a measure of spatial ability c) Electroencephalography and a measure of spatial ability d) Positron Emission Tomography and a measure of spatial ability

35 Techniques of Cognitive Neuroscience QUESTIONS Multiple Choice: 1. You plan to write a study proposal for a project that hypothesizes a positive relationship between connectivity of the prefrontal lobe and visual cortex and success in complex spatial tasks. What is the best technique to apply to your particular research hypothesis? a) Diffusion Tensor Imaging and a measure of spatial ability b) fMRI and a measure of spatial ability c) Electroencephalography and a measure of spatial ability d) Positron Emission Tomography and a measure of spatial ability

36 Techniques of Cognitive Neuroscience QUESTIONS 2. You plan to write a study proposal for a project that hypothesizes that premotor areas respond as part of the “first wave” following a tactile stimulus. What is the best technique and study design to apply to your particular research hypothesis? a) fMRI with a blocked design b) fMRI with ERP c) Electroencephalography with a blocked design d) Electroencephalography with ERP

37 Techniques of Cognitive Neuroscience QUESTIONS 2. You plan to write a study proposal for a project that hypothesizes that premotor areas respond as part of the “first wave” following a tactile stimulus. What is the best technique and study design to apply to your particular research hypothesis? a) fMRI with a blocked design b) fMRI with ERP c) Electroencephalography with a blocked design d) Electroencephalography with ERP


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