Active Representation of Shape and Spatial Location in Man

Baker, S. C.; Frith, C. D.; Frackowiak, R. S. J.; Dolan, Raymond J.

doi:10.1093/cercor/6.4.612

Cited by 158 publications

(112 citation statements)

References 51 publications

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“…The SPACE visual task additionally activated the right anterior insula. In accord with other data for object and spatial memory processing tasks (15)(16)(17)(18), the most significant frontal peak for the FACE task was dissociated from the SPACE task peak. In our data, this separation measured 27.7mm, with the FACE peak more lateral, anterior, and ventral in the right inferior precentral͞inferior frontal sulcus (at Talairach coordinates 45, 6, 41 for composite maps) than the SPACE task peak (at 26, Ϫ12, 50), which was centered more on the superior frontal sulcus.…”

Section: Imaging Results Description Of Anatomical Patterns Of Activsupporting

confidence: 84%

Functional neuroanatomy of executive processes involved in dual-task performance

Adcock¹

2000

Proceedings of the National Academy of Sciences

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The subjective experience of allocating one's attentional resources among competing tasks is nearly universal, and most current models of cognition include a mechanism that performs this allocation; examples include the central executive system and the supervisory attentional system. Yet, the exact form that an executive system might take and even its necessity for cognition are controversial. Dual-task paradigms have commonly been used to investigate executive function. The few neuroimaging studies of these paradigms have yielded contradictory findings. Using functional MRI, we imaged brain function during two dual-task paradigms, each with a common auditory component task (NOUN task) but varying with respect to a visual component task (SPACE or FACE tasks). In each of the two dual-task paradigms, the results showed that the activated areas varied with the component tasks, that all of the areas activated during dual task performance were also activated during the component tasks, and that surplus activation within activated areas during DUAL conditions was parsimoniously accounted for by the addition of the second task. These findings suggest that executive processes may be mediated by interactions between anatomically and functionally distinct systems engaged in performance of component tasks, as opposed to an area or areas dedicated to a generic executive system. W orking memory refers to the cognitive capacity for maintenance and manipulation of information. The widely influential model of working memory proposed by Baddeley and Hitch (1) postulated that working memory was subdivided into contentspecific slave systems. The interplay of these slave systems, the visuo-spatial sketchpad and the articulatory loop, was thought to be regulated by a general-purpose, supramodal mechanism for resource allocation, the central executive, based on the supervisory attentional system originally proposed by Shallice (reviewed in ref.2). Other authors have questioned whether such supervisory systems are necessary components of cognitive models (e.g., refs. 3 and 4). Because the central executive system (CES) is thought to be crucial for coordination of concurrent processing, it has commonly been investigated by using dual-task paradigms in which two behavioral tasks, often with disparate sensory and cognitive processing, are performed concurrently (see, for example refs. 5-7). The few brain mapping studies of these paradigms have yielded contradictory findings (8-11).In the present study, we have used functional MRI to investigate brain activation during two dual-task paradigms. To test the hypothesis that the locations of activations during dual-task performance depended on the specific component tasks performed, we studied two dual-task paradigms. The first combined an auditory verbal categorization task (NOUN) and a visual mental rotation task (SPACE). The second combined the same auditory task with a different visual task involving object identification (FACE) rather than mental rotation. A demonstration that the same b...

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Section: Imaging Results Description Of Anatomical Patterns Of Activsupporting

confidence: 84%

Functional neuroanatomy of executive processes involved in dual-task performance

Adcock¹

2000

Proceedings of the National Academy of Sciences

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“…In fact, several studies report enhanced PFC activation in working memory tasks that is due to increased load or processing duration [1,4]. However, interference-related PFC activation (in the IFJ and the MFG) in the present study was modulated by the task factor, even though the behavioral interference costs were highly similar across tasks.…”

Section: Discussioncontrasting

confidence: 80%

Dissociable brain mechanisms for inhibitory control: effects of interference content and working memory capacity

Mecklinger

Weber

Gunter

et al. 2003

Cognitive Brain Research

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In this study, event-related fMRI was used to examine whether the resolution of interference arising from two different information contents activates the same or different neuronal circuitries. In addition, we examined the extent to which these inhibitory control mechanisms are modulated by individual differences in working memory capacity. Two groups of participants with high and low working memory capacity [high span (HS) and low span (LS) participants, respectively] performed two versions of an item recognition task with familiar letters and abstract objects as stimulus materials. Interference costs were examined by means of the recent negative probe technique with otherwise identical testing conditions across both tasks. While the behavioral interference costs were of similar magnitude in both tasks, the underlying brain activation pattern differed between tasks: The object task interference-effects (higher activation in interference trials than in control trials) were restricted to the anterior intraparietal sulcus (IPS). Interference effects for familiar letters were obtained in the anterior IPS, the left postero-ventral and the right dorsolateral prefrontal cortex (PFC) as well as the precuneus. As the letters were more discernible than the objects, the results suggest that the critical feature for PFC and precuneus involvement in interference resolution is the saliency of stimulus-response mappings.The interference effects in the letter task were modulated by working memory capacity: LS participants showed enhanced activation for interference trials only, whereas for HS participants, who showed better performance and also lower interference costs in the letter task, the above-mentioned neuronal circuitry was activated for interference and control trials, thereby attenuating the interference effects. The latter results support the view that HS individuals allocate more attentional resources for the maintenance of task goals in the face of interfering information from preceding trials with familiar stimulus materials. D

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“…The strong lateralization of the observed word-picture difference is consistent with other recent fMRI studies of encoding (Kelley et al, 1998;Wagner et al, 1998a;Kirchoff et al, 2000) and with working memory studies suggesting a predominance of left PFC activation for verbal material (Paulesu et al, 1993;Awh and Jonides, 1996;Smith and Jonides, 1997) and right PFC for nonverbal material Jonides, 1994, 1995;Baker et al, 1996;Smith et al, 1996). This series of findings suggests that Tulving et al were wise to be cautious in framing their original formulation of the HERA model as relevant to verbal but not necessarily nonverbal material .…”

Section: Material-related Lateralization Of Pfc Functionsupporting

confidence: 86%

The Influence of Explicit Instructions and Stimulus Material on Lateral Frontal Responses to an Encoding Task

Fletcher

2002

NeuroImage

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In this functional magnetic resonance imaging study, we explored the effects of both stimulus material and encoding task demands on activation in lateral prefrontal cortex (PFC). Two factors were manipulated: material type and task instructions. Subjects encoded words or abstract figures (factor 1: stimulus type) and were required to make either a meaningbased or a form-based (letter or shape) decision about each stimulus (factor 2: task instructions). Abstract figures engendered significantly higher levels of right PFC activity than did words. This effect was seen for meaning-based and form-based processing tasks and was significantly greater for the former. We did not observe a differential response of left lateral PFC to verbal and pictorial material. A double dissociation, however, was found within left PFC. A ventrolateral region (within left inferior frontal gyrus) showed the highest levels of activity when words were processed according to their meaning whereas activity in a more dorsolateral region (within left middle frontal gyrus) was greatest when words were processed according to their form (constituent letters). We have therefore observed a main effect of material type in producing lateralized activation of frontal lobes, although the strength of this effect is sensitive to the nature of the task that subjects are asked to perform. Left-side lateral PFC activity is also sensitive to task instructions but this effect was specific to verbal material. The complex patterns of frontal effect counsel against any simple dichotomy of frontal function at the level of either material or task type.

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Active Representation of Shape and Spatial Location in Man

Cited by 158 publications

References 51 publications

Functional neuroanatomy of executive processes involved in dual-task performance

Functional neuroanatomy of executive processes involved in dual-task performance

Dissociable brain mechanisms for inhibitory control: effects of interference content and working memory capacity

The Influence of Explicit Instructions and Stimulus Material on Lateral Frontal Responses to an Encoding Task

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