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Task 4. Everything under control! (Simple Canonical Model (Cognitive…

- - - - Experiment 1: Overall, older participants made more errors and slower than younger. However, younger adults (compared to themsleves) were significantly slower in the second condition in comparison to the first condition (negative priming effect/ suppression effect).
      - Experiment 2: In older people, there was no difference between sequential and non-sequential trails (no inhibition effect).They continue to show no carryover effects in sequential trials. A longer interval does not necessarily permit the buildup of inhibition for older adults. For younger people, stills slower reaction for sequential trials (negative priming effect)
      - conclusion: findings represent the first direct evidence of age-related declines in the basic mechanism of inhibition in selective attention
- - - - Difference with the Inhibitory Deficit Hypothesis: it doesn't give inhibition an explicit role.
  - - - Tonic : active maintainance of information. Becomes disturbed with more advanced age (elderly)
      - Phasic: updating of the contex. More vulnerable with increasing age (starts at middle-age)
  - - - The AX-CPT, participants are instructed to give a positive response
        to the target “X” if it is preceded by an “A.”elderly people tend to produce more
        false alarms than younger people, because they make less effective use of context information (the
        preceding stimulus “A” in this case). the model correctly predicts that older people
        are at a relative advantage in an “AY” condition (where “A” is followed by a “Y”): They do not respond
        to the “Y” because they are less primed by the context stimulus “A” than their younger
        counterparts (YOU ONLY HAVE TO RESPOND TO THE X; WHEN THERE IS AN "A" BEFORE; A tends to prime or bias here). For
        the same reason, older people are at a dis- advantage in a “BX” condition (Dominant responses towards X, must be inhibited now; context information improves performance on these trials. Because they make less use of the “false” context information “B,” they make relative many
        false alarms. They are also slower in this condition. The longer the time they have to respond, the more the false alarm decrease in older adults (more time to process the information). For younger, increasing the interval leads to a decrease in AY mistakes and an increase in BX mistakes) => reduce ability to maintain context information (when the interval is extended, you lose the context information).the “BX” condition, the
        context stimulus “B” is lost by the time that the “X” appears, which increases the chance of a false
        alarm.==> this supports the hypothesis than old people don´t use as effectively context information
        
        Recap
        
        Target-trial: AX (Cue A is followed by probe X). False alarms: elderly > young. Why? Elderly make less effective use of context (A) information
        
        Non-target-trial: AY (A is followed by Y). False alarms: elderly < young. Why? Elderly are less primed by context stimulus A. Advantage elderly.
        
        Non-target-trial: BX (B is followed by X). False alarms+RT: elderly > young. Why? Elderly make less use of the 'false' context information B. Disadvantage elderly.
        
        Interstimulus interval (ISI) increased : False alarm young: increase in AY, decrease BX. False alarms elderly: decrease AY, increase BX. Why? Reduced ability to maintain context information. AY: context A is lost when Y appears, reducing false alarms. BX: context B is lost when X appears, increasing false alarms.
        
        Intact context processing: poor performance AY, good performance BX. Impaired context processing: good performance AY, poor performance BX. There is more interaction with delay between cue and probe, when maintenance functions are disrupted.
- - - - younger adults: PFC activity tends to be left lateralized for verbal stimuli and right lateralized for spatial stimuli. They display significant activity in left PFC during a verbal working memory task but in right PFC during a spatial working memory task.
      - older adults: PFC activity was significant bilaterally during both tasks. In a study by Dixit, et al (2000) evidence was found in a group of middle aged subject for both prefrontal cortices activation =>this suggests that the HAROLD PATTERN develops before old age. The WM data demonstrate that age-related asymmetry reduction may be found not only for process-related asymmetry reductions (episodic vs retrieval) but also for stimuli- related asymmetries (e.g. verbal vs. spatial working memory).
    - - older adults:: older adults displayed little PFC activity during encoding and a bilateral pattern of PFC activity during recall. This reduction in hemispheric asymmetry showed evidence in different kind of tests (recall and recognition) and for different kind of stimuli (verbal and pictorial) = robust and general phenomenon.
      - younger adults: PET and fMRI studies have associated episodic memory encoding and retrieval with prefrontal cortex (PFC) activations. These activations tend to be left lateralized during encoding and right lateralized during retrieval, a pattern known as hemispheric encoding/retrieval asymmetry. This asymmetry has been found for both verbal and non-verbal materials.
      - (2) semantic memory and episodic: These two are considered together because they tend to co-occur during scanning and are very difficult to differentiate => when participants are asked to encode new information (intentional learning and incidental learning).
        The results of different studies showed that it is not about specific functions of left PFC, but rather one based on the overall (decreases in the) distribution of PFC activity across hemispheres
    - - younger adults: PFC activity during face matching was found in the right hemisphere in young adults.
      - older adults: : PFC activity during face matching was found in both hemispheres in older adults.This result suggests that age-related asymmetry reductions can be found not only for higher order cognitive operations, such as episodic and working memory processes, but also for simple cognitive operations, such as face matching.
    - - younger adults:fMRI study showed associated response inhibitions with a network of regions that are strongly lateralized to the right hemispheres, which includes PFC and parietal regions.
      - Older adults: inhibitory control elicited significant activity not only in right PFC but also in left PFC. Age-related increases in the left-hemisphere were also found in the parietal cortex, suggesting that the HAROLD model may generalize beyond PFC.
  - - - Compensation view:: increased bilaterality in older adults could help counteract age-related cognitive deficits. Evidence for it: (1) relation with cognitive performance - evidence that bilateral activity in older adults is associated with enhanced cognitive performance (2) Recovery of function after brain damage: it is assumed that several of the same compensatory mechanisms apply to both age-related and pathology-related neurocognitive dysfunction
      - Dedifferentiation view: the idea that age-related decreases in lateralization are mere by-products of ageing.- Evidence: correlations among different cognitive measures and sensory measures tend to increase with age (not specialized anymore, general activation).
      - 2 theories not incompatible: is possible to argue that neurocognitive dedifferentiation plays a compensatory role in the aging brain => older adults´ cognitive performance is benefited by a decrease in differentiation
    - - Neurogenic : age-related changes in brain activity reflect an alteration in neural architecture, such as changes in the function of different brain regions or their connections of both (Harold model supports more Neurogenic)
        
        Combined with compensation: age-related reduction in hemispheric asymmetry is an adaption of ageing brain that has beneficial effects on cognitive performance
        
        Combined with dedifferentiation: age-related asymmetry reduction reflects the disintegration of brain systems, without a beneficial outcome
        
        Few evidence: accounts more for simple tasks.
      - Psychogenic: Age-related changes in brain activity may reflect changes in cognitive strategies (cognitive architecture)
        
        Combined with compensation: when strategies have beneficial effect on performance
        
        Combined with dedifferentiation: cognitive strategies become less specific, and activation patterns more widespread with ageing
    - - Network view: According to this view, an age-related increase in activation in a certain brain region is not independent of the effects of aging on other brain regions that mediate the task, but rather is the result of a global network change
      - Regional view: Age-related asymmetry reductions reflect s the way in which specific brain regions respond to ageing. The regional view could argue that older adults recruit left PFC during episodic retrieval because of the function and properties of this particular brain region.