neur 3680 midterm ii review

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NEUR 3680 Midterm II Review. Megan Metzler megan.metzler@uleth.ca. Attention. Operational Definition : Controlling how information flows through the brain Key Concepts : Focused on vision, but encompasses all sensory modalities Spotlight of attention Highly complex process - PowerPoint PPT Presentation

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  • NEUR 3680Midterm II ReviewMegan Metzlermegan.metzler@uleth.ca

  • AttentionOperational Definition:Controlling how information flows through the brainKey Concepts:Focused on vision, but encompasses all sensory modalitiesSpotlight of attentionHighly complex process Multiple stimuli commonly presentHemispheric specialization, specialized pathways

  • Conceptualizations of Attention:Irrelevant neural representations disregardedRelevant neural representations enhanced

    Consider examples of evidence supporting each conceptualization.

  • Which conceptualization does the evidence support?Irrelevant neural representations disregardedRelevant neural representations enhanced

    Change blindnessChelazzi et al. (1993)

  • Posner et al. (1980)

    Which conceptualization does the evidence support?Irrelevant neural representations disregardedRelevant neural representations enhanced

  • Models of Attention:Early Selection Model- at sensory levelLate Selection Model- at higher levelHybrid Models- early attenuation of non-attended input and late enhancement of attended input

  • Be able to provide examples of lines of evidence supporting early and late selection models.

  • Which model does the evidence support?Early SelectionLate Selection

    Cherry et al. (p. 496)Used dichotic listening; told to attend to one ear

    Subjects could not report information from the unattended ear.

  • Which model does the evidence support?Early SelectionLate Selection

    Others (Moray, Treisman) (p. 497)Used dichotic listening; told to attend to one ear

    Subjects could report information such as their name (high priority) from the unattended ear

  • Which model does the evidence support?Early SelectionLate Selection

    Hillyard et al. (1960s) Used ERP to study auditory attention

    90 ms post stimulus- likely in or near auditory cortex

  • Differences Between Sustained and Transient AttentionSustained Attention Not environmentally validStrong priming effectTransient AttentionPriming not as effective

    TransientSustained

  • Chelazzi et al. (1993)Neural Correlates of Visual SearchIntracranial recordings at inferior temporal cortex

    Delayed match-to-sample taskCue appears 1.5 seconds before search arrayMonkey saccades to target

    good and poor stimuli are identified for each recorded neuron

  • Note that monkey isnt pre-cued to attend to a locationOnly target features are known prior to choice array onsetIs this testing sustained or transient attention?

    With this paradigm it is possible to measure cell activity during delay, during search, and after selection

    Note that search array always contains a good stimulus for the recorded cell but that might not be the targetChelazzi et al. (1993)Intracranial Recordings of Attentional Selection

  • Initial response of cells is classicalChelazzi et al. (1993)Intracranial Recordings of Attentional Selection

  • Response during delay maintains a representation of the target featureChelazzi et al. (1993)Intracranial Recordings of Attentional Selection

  • Initial response to search array is classicalChelazzi et al. (1993)Intracranial Recordings of Attentional Selection

  • About 200 ms after array onset, response of cell begins to depend on attention

    Response becomes more vigorous if cell is tuned to features of the target (i.e. the selected stimulus)

    Response becomes suppressed if cell is tuned to a non-target distractorChelazzi et al. (1993)Intracranial Recordings of Attentional SelectionIs this evidence of early selection or late selection for attention?

  • Attention OrientingCorbetta et al. (1993)Contralateral parietal and premotor areas active during attention tracking task, BUTConfounded by activations related to stimulusHopfinger et al. (2000)Examined cue-related activationsLeft frontal and parietal structures active

  • Unilateral Spatial NeglectResults from lesion of parietal or temporo-parietal junction (often the right hemisphere)Hemispatial neglect may relate to Extrapersonal space or own body (personal space)the visual field or be object-based

  • Unilateral Spatial NeglectRemember Posners experiment with valid and invalidly cued targets? Heres the same paradigm used with individuals with USN.

  • ExtinctionSubtle form of neglectIndividual fails to attend to stimuli in affected field when stimuli present in unaffected field (when presented one at a time, the individual is able to attend to stimuli in the affected field).

  • QuestionsName a difference between auditory and visual attention (other than the type of stimulus).

  • QuestionsName a difference between auditory and visual attention (other than the type of stimulus).Length of attentional unitsSeveral seconds for auditory, ms for visual

  • QuestionsDescribe an example of neglect in the normal population. What may account for this phenomenon?

  • QuestionsDescribe an example of neglect in the normal population. What may account for this phenomenon?Change blindness (provide an example)Spotlight of attention or early attenuation of irrelevant stimuliIf you missed class, check out BBC.Brain.Story.3of6.The.Minds.Eye.XriD.AC3.NewMov.avi

  • QuestionsGive two examples of how unilateral spatial neglect may impact attention.

  • QuestionsDescribe two examples of how unilateral spatial neglect may impact attention. Auditory neglect for information from one side of external space (usually left) Visual: Object-based neglect, personal neglect, etc. usually of left

  • QuestionsDescribe the Posner paradigm with individuals with parietal lobe lesions. What does it tell us about the parietal lobe?

  • QuestionsDescribe the Posner paradigm with individuals with parietal lobe lesions. What does it tell us about the parietal lobe?Close to normal performance for validly cued trialsPoor performance for invalid trials with target in the affected visual fieldThe parietal lobe may play a role in disengaging the spotlight of attention

    *Earliest stage of modulation20 ms for auditory (P20-50) in auditory cortex, 70 ms for visual (P1) in extrastriate cortex

    ***