Gyula Demeter

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The dual-task paradigm was developed and influenced by this framework which was often used in healthy subjects to study executive functions experimentally by accounting for the interference between concurrent tasks (e.g., Baddeley, 1986; Logie, Gilhooly, & Wynn, 1994). In this paradigm a target task is performed simultaneously with a secondary task thought to involve executive functions and if the two tasks interfere it is concluded that the target task also requires the executive component. One of the most frequent used secondary tasks in the context of working memory model was the verbal random generation task (Baddeley, 1986) in which subjects have to produce in stream letters or numbers as random in order as possible. The dual task method has the advantage that it makes it possible to study the involvement of executive component in different target tasks, the use of different secondary tasks to tap different aspects of executive functions and offers the possibility to dissociate the executive processes from nonexecutive ones by the use of a huge range of verbal and visuospatial secondary tasks (Philips, 1997). Supervisory Attention System model (SAS) Luria conception about the prefrontal cortex, namely, the responsibility for programming, monitoring and controlling behavior had influenced the computational SAS model, characterizing the prefrontal cortex as SAS. The model states that actions are controlled on two levels (Burgess & Shallice, 1997; Norman & Shallice, 1986). The first level, contention scheduling, is automatic and controls routine behaviors when environmental cues are sufficient to trigger appropriate behavior. However, contention scheduling is not always enough to secure an appropriate or intended outcome. At the second level SAS biases contention scheduling and monitors the environment for target cues that indicate when it is appropriate to execute the intended behavior. If the routine selection of actions is insufficient at the first level, for example in new situations, then the involvement of the SAS is necessary to help the cognitive system to achieve the most proper solution. This higher level control mechanism plays an important role in decision making, in error detection, in new situations requiring flexible outcomes as well. The SAS model was extended also to multitasking performance in everyday life (Burgess, Veitch, de lacy Costello, & Shallice, 2000) and according to the authors multitasking behavior include eight different proper characteristics (e.g., engagement in only one task at a particular time period by the subject; unforeseen interruptions and unexpected 10
outcomes etc.) which in many laboratory based tasks are not taken fully into consideration. Evidence supporting this theoretical concept first of all comes from studies of patients with frontal lobe lesions (Chan, Hoosain, Lee, Fan, & Fong, 2003; Shallice, 1988) and from multitasking literature, when healthy subjects intentionally switch attention between different tasks face a considerable cost expressed in reaction time (Allport, Styles, & Hsieh, 1994; Rogers & Monsell, 1995, Burgess, 2000a, 2000b; Gilbert & Shallice, 2002). The most relevant tools to measure executive functions developed based on the concept of SAS are: the Six Elements Test (Shallice & Burgess, 1991), Hayling Sentence Completion Test (Burgess & Shallice, 1996a) and Brixton-Spatial Anticipation Test (Burgess & Shallice, 1996b), Sustained Attention to Response Task (Robertson, Manly, Andrade, Baddeley, & Yiend, 1997), the Behavioral Assessment of Dysexecutive Syndrome (BADS) and Dysexecutive Questionnaires (DEX) (Wilson, Alderman, Burgess, Emslie, & Evans, 1996). To these we can add also those tests which were developed to assess executive attention and depend on the SAS. These include: a) tasks that involve conflict and interference as various versions of the Stroop test; b) tasks that involve shifting between different subtasks or categories as the Wisconsin Card Sorting Test (WCST), the Trail Making B test and verbal fluency tests. Goldman-Rakic’s working memory model One main difference between the models discussed so far and this approach is that it is based on animal, especially on monkey studies. Working memory refers to transient representations of task relevant information and is critical for animals that are not stimulus driven in their behavior. Goldman-Rakic (1992) called working memory the “blackboard of the mind” and linked it to the lateral prefrontal cortex. In her model beside the role of the prefrontal cortex she emphasizes the importance of different catecholamines, especially dopamine in the modulation of inhibitory and excitatory commands between the prefrontal cortex and posterior brain areas. The classical demonstration of these model assumptions comes from prefrontal lesion monkey’s poor performance on the delayed-response task, which requires from the animal to sustain the representation of the previously seen food location during a delayed period. By the increase of the level of dopamine performance on this task is improving. The model does not have its own set of battery or tasks but we can say that this concept of working memory together with Baddeley’s (1986) approach had also influenced the 11
Page 1 and 2: Budapest University of Technology a
Page 3 and 4: 6.3. Study 3: Over-monitoring secon
Page 5 and 6: Glossary of abbreviations ACC Anter
Page 7 and 8: WCST-LS Wisconsin Card Sorting Task
Page 9 and 10: Kivonat Az obszesszív-kompulzív z
Page 11 and 12: Introduction In our daily life we r
Page 13 and 14: Chapter 1. Overview of Obsessive co
Page 15 and 16: ilaterally at the ventromedial pref
Page 17 and 18: Chapter 2. The study of executive f
Page 19: 2.2. Theories and measurement of ex
Page 23 and 24: As far as we know no executive task
Page 25 and 26: The tasks that are most commonly us
Page 27 and 28: 2002) and on the Intra-Dimensional/
Page 29 and 30: Inhibition In the Miyake et al. (20
Page 31 and 32: Table 1. Summary of OCD patients re
Page 33 and 34: Authors Samples Medication Performa
Page 35 and 36: Chapter 3. The study of memory func
Page 37 and 38: 3.2. Prospective memory Prospective
Page 39 and 40: 3.2.1. Theories of prospective memo
Page 41 and 42: According to Guynn (2008) retrieval
Page 43 and 44: intention or the initiation and exe
Page 45 and 46: 3.2.3. Studying PM in OCD While at
Page 47 and 48: 3.2.4. A possible PM model of OCD O
Page 49 and 50: 3.3. The role of inhibition in sele
Page 51 and 52: Further two recent results will be
Page 53 and 54: it, (3) the neuropsychological impa
Page 55 and 56: 4.3. Current neurobiological model
Page 57 and 58: The role of amygdale in the express
Page 59 and 60: 5.1. Main goals 1. To assess the le
Page 61 and 62: Chapter 6. Studies 6.1. Study 1: Im
Page 63 and 64: impairment in this task 15 and othe
Page 65 and 66: Procedure All OCD patients received
Page 67 and 68: series of equal length, and we cons
Page 69 and 70: called error inhibition index (SEII
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Reaction Time Colour Naming Conditi
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which might be impaired in OCD. 9 I
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REFERENCES 1. American Psychiatric
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20. van der Wee NJ., Ramsey NF, Jan
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39. Goodman WK, Price LH, Rasmussen
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6.2. Study 2: Impaired prospective
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Table 1 Sample demographics and bas
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Written instructions were read to t
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Table 2 Hit rate in the two experim
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Comparison of patient and healthy a
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can be concluded that OCD patients
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6.5. Study 5: No retrieval induced
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Experimental design and materials T
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Procedure “In the study phase, pa
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RIF effect in the control group, t(
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Chapter 7. Discussion, conclusions
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and retrospective memory processes
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Bjork, & Bjork, 1994), which was of
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of the dACC contributes to the pers
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Gyula Demeter

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