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  • Johns Motor or sensory?
  • Johns Motor or sensory?
  • Slides

    1. 1. Shantanu Ghosh IIT Delhi An Introduction to Cognitive Neuroscience
    2. 2. The Brain Central organ for control of body’s activities: receives information from peripheral organs via afferent neuronal pathways; controls various organs via efferent pathways Not restricted to physical movement or control of organs, but includes energy metabolism Separated from GC by the blood-brain barrier Works by neurotransmitter release, consumes energy
    3. 3. Frontal lobe Parietal lobe Occipital lobe Temporal lobe Cerebellum pons medulla
    4. 4. Churchland & Sejnowsky, 1988, Science 242 Patch Clamp Fluorescent dyes
    5. 5. Damage in Broca’s area Damage in Wernicke’s area
    6. 6. Ojemann & Whitaker (1978): cortical stimulation “common sites for naming in L1 and L2”, “specific sites for naming in L1 and L2” L2 more variable and extended representation than L1
    7. 7. Fox et al. (2006) PNAS USA 103, 10046-10051 Intrinsically defined dorsal and ventral attention systems and the overlap between them
    8. 8. Cannestra et al. (1998) J Neurophysiol 80:1522-1532 Time course of Calcium transient signaling
    9. 9. Frostig et al. (1990) PNAS USA 87 Comparison of OD maps, rCBV and oxygen delivery changes
    10. 10. activation baseline Donders subtraction method [A + B] – [B] = A Functional map
    11. 11. TONGUE LIP HAND ELBOW SHOULDER HIP KNEE ANKLE Ghosh et al., unpublished data Mapping the sensorimotor areas
    12. 12. S  R Sensory information Hemodynamics- rCBF, rCBV, BOLD Voltage distribution Connectivity Metabolic pathways for information transfer (ion transport, biochemical pathways, etc)
    13. 13. 3 Major Challenges of Cognitive Neuroscience 2 What are the stimuli to be used in the experiment? 3 How do we interpret the data? 1 What are the hypotheses to formulate?
    14. 14. Conceptual framework for a cognitive model NEURAL STRUCTURES 2A NEURAL STRUCTURES 1A NEURAL STRUCTURES 2B NEURAL STRUCTURES 1B Object image f1 f2 f3 … fnFeature extraction level (Early sensory cortex) Processing Level Cortical Level 1 Representational level (Intermediate Cortical level 2) Central Processes (Non-sensory Cortical levels) Higher order global processes (Attention, memory, perception, etc) Object
    15. 15. • Technological advances in imaging and genetics allow the study of the neural activity-behavior interface • A model has to be predictable and replicable in order to lend itself to study Researching the relation between neural activity & behavior
    16. 16. Forced Normalization - A Putative Model • “Forced Normalization is the phenomenon characterised by the fact that, with the occurrence of the psychotic states, the EEG becomes more normal or entirely normal as compared with previous and subsequent EEG findings” • Put more crudely, “there would seem to be epileptics who must have a pathological EEG in order to be mentally sane” Landolt 1952, 1958
    17. 17. Glutamate, GABA and Forced Normalization GABA GLUTAMATE = PSYCHOSIS GABA GLUTAMATE = EPILEPSY
    18. 18. Levels of analysis from the outside; behavioral systems behavior to brain regions activity of neurons in networks structure and connectivity of sub- cellular membranes and systems Psychology/Linguistics Neuropsychology Neurophysiology Molecular/Cellular and Biophysics
    19. 19. The homunculus
    20. 20. Mapping the sensorimotor areas TONGUE LIP HAND ELBOW SHOULDER HIP KNEE ANKLE Ghosh et al., unpublished data
    21. 21. Auditory retrieval of letter names in sequence Singh & Ghosh (2006)
    22. 22. R MOG (BA 18/19, 28, -86, 4), R lingual gyrus (BA 18, 4, -84, 2) L,R cuneus (BA 18/19, -14, -90, 24 and 14, -88, 24) R posterior cingulate gyrus (BA 23, 2, -62, 14) L precentral and lingual gyri (BA 4/1, 17/18) L MFG (BA 10/6, -48, 0, 50 to –38, 60, 12) L,R SPL (BA 7) R lingual gyrus (BA 18) Lexical Structural-functional Concept association Results 2Results 2
    23. 23. Watkins et al 2001 Cereb Cortex
    24. 24. SPM{F} Neurometric functions:Neurometric functions: Responses to stimuli of increasing duration and complexityResponses to stimuli of increasing duration and complexity 0 exposure duration {ms} 8000 exposure duration {ms} 800 Adaptation ofAdaptation of neuronal responsesneuronal responses AttentionalAttentional modulationmodulation time{ms}time{ms}
    25. 25. Context-sensitive responsesContext-sensitive responses timetime stimulus nstimulus nstimulus n-1stimulus n-1 stimulus n+1stimulus n+1 response nresponse n interaction between stimuliinteraction between stimuli
    26. 26. Interactions and context-sensitive effectsInteractions and context-sensitive effects Context 1Context 1 (PARAM absent)(PARAM absent) Context 2Context 2 (PARAM present)(PARAM present) without A & with Awithout A & with A (e.g.. recognition)(e.g.. recognition) 11 22 4433 A 2 x 2 layoutA 2 x 2 layout task 1 2 3 4task 1 2 3 4 interaction effectinteraction effect (A x Context)(A x Context) AA AA Context 1Context 1 Context 2Context 2
    27. 27. Thank you!

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