introduction to cognitive neuroscience

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  • 1. 1 Introduction to Cognitive Neuroscience Dr. Sukhvinder S. Obhi Centre for Cognitive Neuroscience Wilfrid Laurier University

2. 2 Outline Historical Contextualisation Does Cognitive Psychology need the brain? Does neuroscience need cognitive psychology? Introduction to the study of Action 3. 3 4. 4 Epilepsy Epileptic seizures caused by spontaneous firing of neurons Can spread rapidly causing the body to convulse In extreme cases where people are suffering from recurrent seizures frequently, surgery may be considered The aim is to separate the source of the neuronal firing to stop it spreading 5. 5 Wilder Penfield (1954) Awake patient: 6. 6 Penfield Stimulation to the occipital lobe: a star came down towards my nose Stimulation of another (motor) region: those fingers and my thumb gave a jump Temporal lobe: I heard a radio (memory) 7. 7 8. 8 Contextualisation Somehow, functional processes are embedded into the mass of tissue that we call the brain Traditionally the study of cognition included such topics as thinking, perceiving, imagining, remembering, speaking, and planning Cognitive neuroscience considers the same issues, but also from a neural perspective 9. 9 Interdisciplinary Nature of CogNeuro Cognitive Neuroscience Anatomy Neurophysiology Psychology and Neuropsychology Biology Physics Computer Science Neurology 10. 10 Cognitive Neuroscience The study of the neural basis of cognition Pinel (2006) The field of cognitive neuroscience concerns the scientific study of the neural mechanisms underlying cognition and action and is a branch of neuroscience. Cognitive neuroscience overlaps with cognitive psychology, and focuses on the neural substrates of mental processes and their behavioral manifestations. The boundaries between psychology, psychiatry and neuroscience have become quite blurred. Cognitive neuroscientists tend to have a background in experimental psychology, neurobiology, neurology, physics, and mathematics. adapted by S.S. Obhi from wikipedia* *(never use wikipedia as a single reference source always cross check the information before citing it and provide other refs!!) 11. 11 Why interdisciplinary? Theory and methods of Cognitive Neuroscience are often very complex Individuals with different types of training collaborate to make it happen All good fMRI (brain imaging) centres have a Physics group that works with experimental psychologists to optimize the scanning methods for various types of research A great example of how researchers interested in a common topic can work together more usefully than working alone! 12. 12 Brain imaging webpage Psychologist Mathematician MD Physicist Neurologist 13. 13 History During most of history humans were too busy to think about thought! Thought about thought may have come about at the stage in history where day-to-day survival did not occupy every hour of every day Probably linked to the beginnings of farming and domesticating animals etc 14. 14 Historical Perspective Long history of interest in how the brain creates our mental world Central question: how does the physical substance of the brain give rise to our feelings, thoughts, emotions and actions? Historically referred to as the mind-body problem 15. 15 Descartes & Dualism Rene Descartes (1596-1650) was an early proponent of dualism Mind non-physical and immortal, body physical and mortal They interact in the pineal gland in the centre of the brain According to Descartes, sensory stimulation would cause vibrations in the body/brain that would be picked up by the pineal gland which would generate a non-physical sense of awareness 16. 16 Critics of Descartes Spinoza (1623-1677) Mind and Brain were just two different levels of explanation for the same thing but not two different things Termed Dual-Aspect Theory still popular today 17. 17 Levels of Explanation This is a useful concept Can explain phenomena at the cellular level, at the neuronal population level and at the behavioural level One of the goals of the scientific study of mind and brain is to understand how things at one level are related to things at another 18. 18 Reductionism A popular approach to the mind-body problem Cognitive, mind based concepts are currently useful but they will eventually be replaced by biological constructs (just as much of physical chemistry can be reduced to physics) So emotions, thoughts, desires etc, will be described simply as patterns of neuronal firing Many believe this is too extreme there must be some validity in our own sense of self, perhaps over and above the physical working of the brain Pure reductionist view sometimes called materialism 19. 19 Cautionary Examples Understanding individual liver cells is not enough to gain an understanding of liver function Similarly, understanding atoms in a solid, does not tell you about the properties of the macroscopic solid Understanding the hardware of a computer is insufficient to understand the jobs a computer performs To believe fully in reductionism is to believe that low level processes always fully explain high level processes 20. 20 Scientific Approaches to Mind & Brain Thought started very early, Ancient Greece (if not before that!) Aristotle (384-322 BC) noted that the ratio of brain size to body size was greatest in more intellectually advanced species (humans) But wrongly thought that cognition was centered at the heart and that the brain was a cooling system Note: Roots of much of psychology (and therefore cognitive neuroscience) are in Philosophy 21. 21 Egyptian Contributions Ancient Egypt scientists had access to condemned criminals There are reports that scientists actually vivisected these people (note: to vivisect is to dissect, cut or perform surgery on a living animal)!! In this age speculation that the brain controlled different behaviours emerged but wrongly placed emphasis on the ventricles (cavities in the brain) 22. 22 Roman Contributions Galen a surgeon who worked on gladiators 23. 23 Roman Contributions Galen (AD 130-201) thought that war and Gladiator games were the greatest school of surgery Identified many major structures in the brain Also credited for observing that nerves project to and from the brain But was misguided in thinking that mental experiences arose out of the ventricles an idea that went unchallenged for 1500 years! 24. 24 Rene Descartes (1596-1650) Non-physical mind interacts with brain through pineal gland Often referred to the flow of spirits through nerves Compared to mechanical contraptions of his time Mind-body dualism 25. 25 Lack of interest in the cortex Old pictures of the brain are interesting since they tended to draw the ventricles in exquisite detail and then just crudely draw the cortex! 26. 26 Luigi Galvani (1737-98) Applied electrical currents to motor nerve and made frogs legs move Linked electricity to the functions of the nervous system But wrongly thought that nerves and muscles contained an electric fluid 27. 27 Golgi & Cajal Battle between 2 neuro-anatomists in Italy & Spain Golgi (1843-1926) developed a staining technique that could stain individual neurons Cajal (1852-1934) went on to show that individual neurons were discrete entities and that neural matter was not a continuous mass of processes 28. 28 Golgi stained neurons 29. 29 Insights into Morphology Morphology = study of the structure of biological organisms Many early contributions were based on dissections and really attempted to inform knowledge of structure 30. 30 Shift to cortical interest & functions Gall & Spurzheim (1810) their drawings started to focus on the cortex a bit more Gall was a proponent of phrenology localization of traits in the brain 31. 31 The birth of Psychology Only really happened toward the end of the nineteenth century In a sense, it took the emphasis of the study of the mind away from its biological roots This was necessary since the topics of interest to early psychologists (James, Wundt etc) included such things as consciousness, attention and personality Biological study of the mind had, until this time, very little to say about these issues 32. 32 Early Psychologists William James (USA) Wilhelm Wundt (Germany) Sigmund Freud (Austria) 33. 33 The gap between Psychology & Biology It is possible to make coherent and testable theories about cognition (mental processes) without referring to the brain Cognitive Psychologists have done this since the formation of the discipline - taking the information processing approach to cognition What are the processing steps underlying various mental phenomena? Use the computer metaphor in which the brain is analogous to a computer 34. 34 Computer Metaphor The brain is like a computer - popularized in the 1950s coincident with the invention of the computer Famous model that uses this framework is Broadbents model in which perceptual processes are followed by attentional processes which move information into short-term memory 35. 35 Box and Arrow models Extraction of physical properties Extraction of abstract properties Filter Incoming Stimuli A sequence of processing stages Implication of these models was that you could understand the steps needed to perform a certain task without reference to the brain Much as you can figure out how a computer program works without reference to the hardware 36. 36 Processing not always sequential Important concept in the cognitive approach is that it is possible to have parallel processing Stages of processing can be interactive meaning that higher level processes can begin before low level processes are completed E.g., Early feature extraction and two visual systems Back projections in vision 37. 37 Box and Arr


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