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124
Rethinking feelings: an FMRI study of the cognitive regulation of emotion.
- Journal of Cognitive Neuroscience,
, 2002
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The role of prefrontal cortex in working-memory capacity, executive attention, and general fluid intelligence: An individual-differences perspective
, 2002
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Age differences in the frontal lateralization of verbal and spatial working memory revealed by PET
- J Cogn Neurosci
, 2000
"... & Age-related decline in working memory figures promi-nently in theories of cognitive aging. However, the effects of aging on the neural substrate of working memory are largely unknown. Positron emission tomography (PET) was used to investigate verbal and spatial short-term storage (3 sec) in ol ..."
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Cited by 109 (3 self)
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& Age-related decline in working memory figures promi-nently in theories of cognitive aging. However, the effects of aging on the neural substrate of working memory are largely unknown. Positron emission tomography (PET) was used to investigate verbal and spatial short-term storage (3 sec) in older and younger adults. Previous investigations with younger subjects performing these same tasks have revealed asymmetries in the lateral organization of verbal and spatial working memory. Using volume of interest (VOI) analyses that specifically compared activation at sites identified with working memory to their homologous twin in the opposite hemisphere, we show pronounced age differences in this organization, particularly in the frontal lobes: In younger adults, activation is predominantly left lateralized for verbal
From Perception to Action: Temporal Integrative Functions of Prefrontal and Parietal Neurons
- Cereb. Cortex
, 1999
"... The dorsolateral prefrontal cortex (DPFC) and the posterior parietal cortex (PPC) are anatomically and functionally interconnected, and have been implicated in working memory and the preparation for behavioral action. To substantiate those functions at the neuronal level, we designed a visuomotor ta ..."
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Cited by 74 (1 self)
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The dorsolateral prefrontal cortex (DPFC) and the posterior parietal cortex (PPC) are anatomically and functionally interconnected, and have been implicated in working memory and the preparation for behavioral action. To substantiate those functions at the neuronal level, we designed a visuomotor task that dissociated the perceptual and executive aspects of the perception–action cycle in both space and time. In that task, the trial-initiating cue (a color) indicated with different degrees of certainty the direction of the correct manual response 12 s later. We recorded extracellular activity from 258 prefrontal and 223 parietal units in two monkeys performing the task. In the DPFC, some units (memory cells) were attuned to the color of the cue, independent of the response-direction it connoted. Their discharge tended to diminish in the course of the delay between cue and response. In contrast, few color-related units were found in PPC, and these did not show decreasing patterns of delay activity. Other units in both cortices (set cells) were attuned to response-direction and tended to accelerate their firing in anticipation of the response and in proportion to the predictability of its direction. A third group of units was related to the determinacy of the act; their firing was attuned to the certainty with which the animal could predict the correct response, whatever its direction. Cells of the three types were found closely intermingled histologically. These findings further support and define the role of DPFC in executive functions and in the temporal closure of the perception– action cycle. The findings also agree with the involvement of PPC in spatial aspects of visuomotor behavior, and add a temporal integrative dimension to that involvement. Together, the results provide physiological evidence for the role of a prefrontal–parietal network in the integration of perception with action across time.
Goal-Directed and Stimulus-Driven Determinants of Attentional Control
, 2000
"... Selective visual attention to objects and locations depends both on deliberate behavioral goals that regulate even early visual representations (goal-directed influences) and on autonomous neural responses to sensory input (stimulus-driven influences). In this chapter, I argue that deliberate goal- ..."
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Cited by 56 (3 self)
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Selective visual attention to objects and locations depends both on deliberate behavioral goals that regulate even early visual representations (goal-directed influences) and on autonomous neural responses to sensory input (stimulus-driven influences). In this chapter, I argue that deliberate goal-directed attentional strategies are always constrained by involuntary, ”hard-wired computations, and that an appropriate research strategy is to delineate the nature of the interactions imposed by these constraints. To illustrate the inter-action between goal-directed and stimulus-driven attentional control, four domains of visual selection are reviewed. First, selection by location is both spatially and temporally limited, reflecting in part early visual representations of the scene. Second, selection by feature is an available attentional strategy, but it appears to be mediated by location, and feature salience alone does not govern the deployment of attention. Third, early visual seg-mentation processes that parse a scene into perceptual object representations enable object-based selection, but they also enforce selection of entire objects, and not just isolated features. And fourth, the appearance of a new perceptual object captures attention in a stimulus-driven fashion, but even this is subject to some top-down attentional control.
Increased Brain Activity in Frontal and Parietal Cortex Underlies the Development of Visuospatial Working Memory Capacity during Childhood
"... & The aim of this study was to identify changes in brain activity associated with the increase in working memory (WM) capacity that occurs during childhood and early adulthood. Functional MRI (fMRI) was used to measure brain activity in subjects between 9 and 18 years of age while they performed ..."
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Cited by 51 (5 self)
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& The aim of this study was to identify changes in brain activity associated with the increase in working memory (WM) capacity that occurs during childhood and early adulthood. Functional MRI (fMRI) was used to measure brain activity in subjects between 9 and 18 years of age while they performed a visuospatial WM task and a baseline task. During performance of the WM task, the older children showed higher activation of cortex in the superior frontal and intraparietal cortex than the younger children did. A second analysis found that WM capacity was significantly correlated with brain activity in the same regions. These frontal and parietal areas are known to be involved in the control of attention and spatial WM. The development of the functionality in these areas may play an important role in cognitive development during childhood. &
What"-Then-"Where" in visual working memory: an event-related fMRI study
- Journal of Cognitive Neuroscience
, 1999
"... Behavioral studies indicate that spatial and object working memory are computed by dissociable subsystems. We investi-gated the neural bases of this dissociation with a whole-brain fMRI design and analysis technique that permitted direct as-sessment of delay-period activity, uncontaminated by other ..."
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Cited by 49 (4 self)
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Behavioral studies indicate that spatial and object working memory are computed by dissociable subsystems. We investi-gated the neural bases of this dissociation with a whole-brain fMRI design and analysis technique that permitted direct as-sessment of delay-period activity, uncontaminated by other components of the trial. The task employed a “what”-then-“where ” design, with an object and a spatial delay period incorporated in each trial; within-trial order of delay conditions was balanced across each scan. Our experiment failed to ªnd evidence, at the single-subject level and at the group level, for anatomical segregation of spatial and object working memory function in the frontal cortex. Delay-period activity in the caudate nucleus revealed a sensitivity to position in the trial in the spatial, but not the object, condition. In posterior regions, spatial delay-period activity was associated with preferential recruitment of extrastriate areas falling within Brodmann’s area 19 and, less reliably, the superior parietal lobule. Object-speciªc delay-period activity was found predominantly in ventral re-gions of the posterior cortex and demonstrated more topo-graphic variability across subjects than did spatial working memory activity.
Working memory for letters, shapes, and locations: FMRI evidence against stimulus-based regional organization in human prefrontal cortex.
- NeuroImage,
, 2000
"... Investigations of working memory (WM) systems in the frontal cortex have revealed two stimulus dimensions along which frontal cortical representations may be functionally organized. One hypothesized dimension dissociates verbal from nonverbal WM processes, dividing left from right frontal regions. ..."
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Cited by 48 (6 self)
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Investigations of working memory (WM) systems in the frontal cortex have revealed two stimulus dimensions along which frontal cortical representations may be functionally organized. One hypothesized dimension dissociates verbal from nonverbal WM processes, dividing left from right frontal regions. The second hypothesized dimension dissociates spatial from nonspatial WM, dividing dorsal from ventral frontal regions. Here we used functional magnetic resonance imaging to probe WM processes associated with three different types of stimuli: letters (verbal and nonspatial), abstract shapes (nonverbal and nonspatial), and locations (nonverbal and spatial). In a series of three experiments using the "n-back" WM paradigm, direct statistical comparisons were made between activation patterns in each pairwise combination of the three stimulus types. Across the experiments, no regions that demonstrated responses to WM manipulations were discovered to be unique to any of the three stimulus types. Therefore, no evidence was found to support either a left/right verbal/nonverbal dissociation or a dorsal/ventral spatial/nonspatial dissociation. While this could reflect a limitation of the present behavioral and imaging techniques, other factors that could account for the data are considered, including subjects' strategy selection, encoding of information into WM, and the nature of representational schemes in prefrontal cortex.
The neural system underlying Chinese logograph reading
- NeuroImage
, 2001
"... Written Chinese as logographic script differs notably from alphabets such as English in visual form, orthography, phonology, and semantics. Thus, research on the Chinese language is important to advance our understanding of the universality and particularity of the organization of language systems i ..."
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Cited by 41 (7 self)
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Written Chinese as logographic script differs notably from alphabets such as English in visual form, orthography, phonology, and semantics. Thus, research on the Chinese language is important to advance our understanding of the universality and particularity of the organization of language systems in the brain. In this study, we examine the neural systems associated with logographic reading using functional magnetic resonance imaging. Two experimental tasks were devised, one based on semantic decision and the other on homophone decision. Compared to the fixation baseline, peak activations resulting from semantic as well as homophony decisions were localized in the left middle frontal gyrus (BA 9). Left inferior frontal cortex also mediated Chinese processing. In addition, more right hemisphere cortical regions (i.e., BAs 47/45, 7, 40/39, and the right visual system) were involved in reading Chinese relative to reading English. This is attributed to the square shape of the logograph which requires an elaborated analysis of the spatial information and locations of various strokes comprising the logographic character. We suggest that the left middle frontal area (BA 9) coordinates and integrates the intensive visuospatial analysis demanded by logographs ’ square configuration and the semantic (or phonological) analysis required by the present experimental tasks. Our study has implicated brain regions common to both logographic and alphabetic languages as well as brain regions specialized in processing logographs. © 2001 Academic Press
Sustained mnemonic response in the human middle frontal gyrus during on-line storage of spatial memoranda
- Journal of Cognitive Neuroscience
, 2002
"... & The mapping of cognitive functions to neural systems is a central goal of cognitive neuroscience. On the basis of homology with lesion and physiological studies in nonhuman primates, Brodmann’s area (BA) 46/9 in the middle frontal gyrus (MFG) has been proposed as the cortical focus for both th ..."
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Cited by 39 (1 self)
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& The mapping of cognitive functions to neural systems is a central goal of cognitive neuroscience. On the basis of homology with lesion and physiological studies in nonhuman primates, Brodmann’s area (BA) 46/9 in the middle frontal gyrus (MFG) has been proposed as the cortical focus for both the storage as well as processing components of working memory in the human brain, but the evidence on the segregation of these components and their exact areal localization has been inconsistent. In order to study this issue and increase the temporal resolution of functional mapping, we disambiguated the storage component of working memory from sensory and motor responses by employing functional magnetic resonance imaging (fMRI) in spatial delayed-response (DR) tasks with long delay intervals and different conditions of demand. We here show that BA 46 can support a sustained mnemonic response for as long as 24 sec in a high-demand task and the signal change in this area exceeded that in the other prefrontal areas examined. Our findings support a conservation of functional architecture between human and nonhuman primate in showing that the MFG is prominently engaged in the storage of spatial information. &
