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Cognitive Neuroscience

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Cognitive Neuroscience

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    1. Cognitive Neuroscience Maria Gardani Department of Psychology Summer School 2006

    3. Brain Primate brain appeared appr. 20 million years ago and evolution ? brain as we know it..or not!Primate brain appeared appr. 20 million years ago and evolution ? brain as we know it..or not!

    4. The brain story Central issue: Does the brain works in concert or parts of it work independently? Huge revolution in our understanding of the nervous system started in Italy and Spain Dominant view still changesover the past 100 years! Dominant view still changesover the past 100 years!

    5. Golgi & Cajal Camillo Golgi: develop a stain that impregnated individual neurons (silver stain) Santiago Ramon y Cajal: found that neurons are discrete entities Italian neuroanatomist/ permitted full visualisation of single neurosn Italian neuroanatomist/ permitted full visualisation of single neurosn

    6. SCN (Silver Stain-Cresyl Violet)

    7. The battle: Italy vs Spain Cajal made his discovery using the Silver stain that discovered by Golgi 1906 Nobel prize award to both Cajal established the neuron doctrine Yet Golgi refuted him in Stockholm!!Yet Golgi refuted him in Stockholm!!

    8. What is cognitive neuroscience? Study of neural mechanisms underlying cognition Cognitive psychology?understand the mind Cognitive neuroscientists?seek to understand how different mental processes take place in the brain Higly interdisciplinary area in which psychology, neuroscience, linguistics, philosophy, and computer science, as well as artificial intelligence, anthropology and biology are its specialized or applied branches. Higly interdisciplinary area in which psychology, neuroscience, linguistics, philosophy, and computer science, as well as artificial intelligence, anthropology and biology are its specialized or applied branches.

    9. Historical overview Ancient Greece (Plato, Aristotle) 17th c. (Descartes: res extensa & res cogitans) Descartes : popularized the notion that the body and the mind were two separate entities, res extensa and res cogitans thinking things and extended things, or minds and bodies Descartes : popularized the notion that the body and the mind were two separate entities, res extensa and res cogitans thinking things and extended things, or minds and bodies

    10. Historical overview Phrenologists (Gall) Paul Broca, 1861 Carl Wernicke, 1876 Analysis of the skull: personality of a person would be on the skull. Increase in local brain size would cause a bump in to the overlying skull Broca treated a patient who could understant language but could not speak Part that was damaged was left frontal lobe (include a slide here!) Wernicke a patient that could talk but made little sense (not understand written or spoken language) Analysis of the skull: personality of a person would be on the skull. Increase in local brain size would cause a bump in to the overlying skull Broca treated a patient who could understant language but could not speak Part that was damaged was left frontal lobe (include a slide here!) Wernicke a patient that could talk but made little sense (not understand written or spoken language)

    11. Philosophy Two main positions: empiricism & rationalism Empiricism: direct sensory experience produces simple ideas and concepts British philosophers: Thomas Hobbes, David Hume, John Locke, J.S. Mill British philosophers! All emphasised the role of experienceBritish philosophers! All emphasised the role of experience

    12. 20th century J.B. Watson : promoted the notion that he could take a baby and turn it to anything he wanted (little Albert) Arise from the associasionist view Watson:American psychologist End of behaviourism overnight: started to think of cognitions not behaviours! Behaviourism ended in 1950 Arise from the associasionist view Watson:American psychologist End of behaviourism overnight: started to think of cognitions not behaviours! Behaviourism ended in 1950

    13. J.B. Watson Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors. I am going beyond my facts and I admit it, but so have the advocates of the contrary and they have been doing it for many thousands of years. (1930)

    14. 20th century George Miller the magical number seven plus or minus two Noam Chomsky ideas on syntactic theories three models of language

    15. Cognitive neuroscience Term coined in a New York taxi in the late 1970 M. Cazzaniga was in a taxi with George Miller on the way to a dinner held for scientist to study how the brain enables the mind

    16. Topics of interest Attention Language processing Learning and development Memory Perception and action Artificial intelligence

    17. Attention Attention is the selection of important information Attention is seen as a spotlight Cocktail party problem? Cherry, 1953

    18. Language processing

    19. Language processing Ability to learn and understand language Linguistics: have found that, while humans form sentences in ways apparently governed by very complex systems, they are remarkably unaware of the rules that govern their own speech. originally the study of language was based in the humanities In the last 50 years they started studying language as a cognitive phenomenon Language: investigation of the sound patterns of speech to the meaning of words and whole sentences originally the study of language was based in the humanities In the last 50 years they started studying language as a cognitive phenomenon Language: investigation of the sound patterns of speech to the meaning of words and whole sentences

    20. Learning and development Processes that acquire information over time Nativist view Empiricist view

    21. Memory Short-term memory Long-term memory Working memory Main stages in formation & retrieval: Encoding Storage Retrieval

    22. Perception (1) How are we able to recognize objects?, (2) Why do we perceive a continuous visual environment, even though we only see small bits of it at any one time? One tool for studying visual perception is by looking at how people process visual illusions Necker cube: example of bistable effect that it can be perceived as orientated in 2 different dimensions!(1) How are we able to recognize objects?, (2) Why do we perceive a continuous visual environment, even though we only see small bits of it at any one time? One tool for studying visual perception is by looking at how people process visual illusions Necker cube: example of bistable effect that it can be perceived as orientated in 2 different dimensions!

    23. Perception Ability to take information in via the senses Vision and hearing Haptic (tactile), olfactory, gustatory stimuli

    24. Research methods Behavioural experiments measure behavioural responses Reaction time: stimulus-response time Psychophysical responses: judgements of some physical property e.g. loudness of stimulus Reaction time. The time between the presentation of a stimulus and an appropriate response can indicate differences between two cognitive processes, and can indicate some things about their nature. For example, if in a search task the reaction times vary proportionally with the number of elements, then it is evident that this cognitive process of searching involves serial and not parallel processing. Correlation of subjective scales between individuals can show cognitive or sensory biases as compared to actual physical measurements. Some examples include: sameness judgments for colors, tones, textures, etc. threshold differences for colors, tones, textures, etc. Reaction time. The time between the presentation of a stimulus and an appropriate response can indicate differences between two cognitive processes, and can indicate some things about their nature. For example, if in a search task the reaction times vary proportionally with the number of elements, then it is evident that this cognitive process of searching involves serial and not parallel processing. Correlation of subjective scales between individuals can show cognitive or sensory biases as compared to actual physical measurements. Some examples include: sameness judgments for colors, tones, textures, etc. threshold differences for colors, tones, textures, etc.

    25. Research methods Eye tracking: The fixation point of the eyes is linked to an individual's focus of attention Eye movements reflect online decision making during a task, and they provide us with some insight into the ways in which those decisions may be processed

    26. Eye tracking

    27. Research methods Brain imaging techniques Brain imaging involves analyzing activity within the brain while performing various cognitive tasks

    28. Brain Imaging 2 types: structural: overall structure and precise diagnosis of intracranial disease and injury functional: neurological and cognitive science research and building computer interfaces

    29. Neuroimaging EEG MEG CAT MRI fMRI PET SPECT

    30. 1.Electroencephalography Electroencephalography is the neurophysiologic measurement of the electrical activity of the brain by recording from electrodes placed on the scalp or, in special cases, on the cortex. This image is one of the first EEGs, appearing in Berger's First Report. It is a portion of fig. 13 from Berger's first publication on EEG (1929!!) Electroencephalography is the neurophysiologic measurement of the electrical activity of the brain by recording from electrodes placed on the scalp or, in special cases, on the cortex. This image is one of the first EEGs, appearing in Berger's First Report. It is a portion of fig. 13 from Berger's first publication on EEG (1929!!)

    31. EEG (electroencephalogram)

    32. EEG (electroencephalogram) Clinical use: Epilepsy, sleep disorders, coma, brain death Research use: neuroscientist, biological psychiatrist

    33. EEG.. Methods: Electrodes on the scalp Strengths: non-invasive,time resolution is high, the only measure of brain electric activity Limitations: cannot discriminate btwn individual action potentials, limited anatomical specificity

    34. 2.Magnetoencephalography (MEG)

    35. MEG Measures magnetic fields produced by electrical activity in the brain Strengths: good spatial resolution, extr. High temporal resolution

    36. 3.Computed tomography (CT or CAT) The arrow indicates damage caused by strokeThe arrow indicates damage caused by stroke

    37. CAT A series of x-rays taken from different directions A series of x-rays taken from different directions

    38. 4.Magnetic Resonance Imaging (MRI) High-resolution sagittal: MRI slice at the midline.High-resolution sagittal: MRI slice at the midline.

    39. MRI uses magnetic fields and radio waves to produce high quality two- or three-dimensional images of brain structures without injecting radioactive tracers magnetic resonance tomography (MRT) or nuclear magnetic resonance (NMR), is a method used to visualize the inside of living organisms as well as to detect the amount of bound water in geological structures magnetic resonance tomography (MRT) or nuclear magnetic resonance (NMR), is a method used to visualize the inside of living organisms as well as to detect the amount of bound water in geological structures

    40. MRI In clinical practice, MRI is used to distinguish pathologic tissue (such as a brain tumor) from normal tissue In clinical practice, MRI is used to distinguish pathologic tissue (such as a brain tumor) from normal tissue

    41. MRI Strengths: high temporal resolution, high anatomical detailed images, high contrast resolution,harmless to patients Limitations: cost, low functional information

    42. 4.Functional magnetic resonance imaging (fMRI) Axial MRI slice at the level of the basal ganglia: motor & learning functions, showing fMRI BOLD signal changes overlayed in red (increase) and blue (decrease) tones.Axial MRI slice at the level of the basal ganglia: motor & learning functions, showing fMRI BOLD signal changes overlayed in red (increase) and blue (decrease) tones.

    43. fMRI relies on the paramagnetic properties of oxygenated and deoxygenated hemoglobin to see images of changing blood flow in the brain associated with neural activity The most recent imaging technique Blood cells when active they consume oxygen carried by hemoglobin/local response to utilitasation of oxygen is the blood flow increase in region of neuronal activity with a delay of 1-5 sec. Allows subject to presented with information and gives information on the structures activatedThe most recent imaging technique Blood cells when active they consume oxygen carried by hemoglobin/local response to utilitasation of oxygen is the blood flow increase in region of neuronal activity with a delay of 1-5 sec. Allows subject to presented with information and gives information on the structures activated

    44. fMRI Strengths: high resolution, non-invasive, good spatial resolution (3-6 millimeters) Limitations: low spatial resolution, high cost, poor temporal resolution, Temporal res. Poor compared to EEGTemporal res. Poor compared to EEG

    45. 5. Positron Emission Tomography (PET) measures emissions from radioactively labeled metabolically active chemicals that have been injected into the bloodstream produce two or three-dimensional images of the distribution of the chemicals throughout the brain The data produce 2 or 3D imagesThe data produce 2 or 3D images

    46. PET

    47. PET Strengths: high resolution and speed of completion (past preferred imaging technique) Limitations: radioactivity decays rapidly allows only short tasks!

    48. Single photon emission computed tomography (SPECT) uses gamma ray emitting radioisotopes and a gamma camera to record data that a computer uses to construct two- or three-dimensional images of active brain regions

    49. Essay title Neuroscience research is focused on understanding the relationship between brain function, cognitive processing and behaviour in general. Discuss how the different tools available in neuroscientists today can answer questions regarding a mental process (i.e. memory, language,attention). Compare two of these tools in terms of function and efficacy.

    50. Thank you

    51. Thanx

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