Covariance Analysis of Functional Interactions in the Brain Using Metabolic and Blood Flow Data

Horwitz, Barry; Soncrant, Timothy T.; Haxby, James V.

doi:10.1007/978-94-011-2712-7_7

Cited by 42 publications

(38 citation statements)

References 61 publications

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“…The SEM network approach described here is an example of a covariance-based approach (Horwitz & McIntosh, 1993;Horwitz, Soncrant, & Haxby, 1992). The basic hypothesis of different covariance based approaches is that the intrinsic variability in the neural response, during a cognitive state or particular task, will emulate the relevant functional interactions or effective connectivity (Friston, 1994;Friston, 1995).…”

Section: Some Assumptions and Limitations Of The Network Approachmentioning

confidence: 99%

“…Several sources of interregional covariances have been proposed (Horwitz et al, 1992) and the actual sources of the observed covariances are largely unknown. However, some of the proposed sources may give rise to spurious correlations that are necessarily confounded with correlations arising because of the effective connectivity or the functional architecture (e.g., adaptation, fatigue, attentional drift; cf.…”

Section: Covariance Sourcesmentioning

confidence: 99%

“…However, some of the proposed sources may give rise to spurious correlations that are necessarily confounded with correlations arising because of the effective connectivity or the functional architecture (e.g., adaptation, fatigue, attentional drift; cf. Horwitz et al, 1992 andFriston, 1997). Obvious potential confounders in the study of interregional covariances are global effects.…”

Section: Covariance Sourcesmentioning

confidence: 99%

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Language Processing Modulated by Literacy: A Network Analysis of Verbal Repetition in Literate and Illiterate Subjects

Petersson

Reis

Askelöf

et al. 2000

Journal of Cognitive Neuroscience

158

114

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Abstract& Previous behavioral and functional neuroimaging data indicate that certain aspects of phonological processing may not be acquired spontaneously, but are modulated by learning an alphabetic written language, that is, learning to read and write. It appears that learning an alphabetic written language modifies the auditory-verbal (spoken) language processing competence in a nontrivial way. We have previously suggested, based on behavioral and functional neuroimaging data, that auditory-verbal and written language interact not only during certain language tasks, but that learning and developing alphabetic written language capacities significantly modulates the spoken language system. Specifically, the acquisition of alphabetic orthographic knowledge has a modulatory influence on sublexical phonological processing and the awareness of sublexical phonological structure. We have suggested that developing an orthographic representation system for an alphabetic written language, and integrating a phoneme± grapheme correspondence with an existing infrastructure for auditory-verbal language processing, will result in a modified language network. Specifically, we suggest that the parallel interactive processing characteristics of the underlying language-processing brain network differ in literate and illiterate subjects. Therefore, the pattern of interactions between the regions of a suitably defined large-scale functional-anatomical network for language processing will differ between literate and illiterate subjects during certain language tasks. In order to investigate this hypothesis further, we analyzed the observed covariance structure in a PET data set from a simple auditoryverbal repetition paradigm in literate and illiterate subjects, with a network approach based on structural equation modeling (SEM). Based on a simple network model for language processing, the results of the present network analysis indicate that the network interactions during word and pseudoword repetition in the illiterate group differ, while there were no significant differences in the literate group. The differences between the two tasks in the illiterate group may reflect differences in attentional modulation of the language network, executive aspects of verbal working memory and the articulatory organization of verbal output. There were no significant differences between the literate and illiterate group during word repetition. In contrast, the network interactions differed between the literate and illiterate group during pseudoword repetition. In addition to differences similar to those observed in the illiterate group between word and pseudoword repetition, there were differences related to the interactions of the phonological loop between the groups. In particular, these differences related to the interaction between Broca's area and the inferior parietal cortex as well as the posterior-midinsula bridge between Wernicke's and Broca's area. In conclusion, the results of this network analysis are consistent with our previously pr...

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Section: Some Assumptions and Limitations Of The Network Approachmentioning

confidence: 99%

Section: Covariance Sourcesmentioning

confidence: 99%

Section: Covariance Sourcesmentioning

confidence: 99%

See 1 more Smart Citation

Language Processing Modulated by Literacy: A Network Analysis of Verbal Repetition in Literate and Illiterate Subjects

Petersson

Reis

Askelöf

et al. 2000

Journal of Cognitive Neuroscience

158

114

View full text Add to dashboard Cite

show abstract

“…To complement the subtraction technique, we have developed a method for examining the covariance, or functional connectivity, between regions during the performance of individual tasks by using data obtained from positron emission tomography (PET) (8)(9)(10). The main assumption of this method is that subject-to-subject differences in using a systems-level neural network result in strongly correlated neural activity [indexed by regional cerebral blood flow (rCBF)] between network elements.…”

mentioning

confidence: 99%

Functional connectivity of the angular gyrus in normal reading and dyslexia

Horwitz

Rumsey

Donohue

1998

Proc. Natl. Acad. Sci. U.S.A.

533

336

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The classic neurologic model for reading, based on studies of patients with acquired alexia, hypothesizes functional linkages between the angular gyrus in the left hemisphere and visual association areas in the occipital and temporal lobes. The angular gyrus also is thought to have functional links with posterior language areas (e.g., Wernicke's area), because it is presumed to be involved in mapping visually presented inputs onto linguistic representations. Using positron emission tomography , we demonstrate in normal men that regional cerebral blood f low in the left angular gyrus shows strong within-task, across-subjects correlations (i.e., functional connectivity) with regional cerebral blood f low in extrastriate occipital and temporal lobe regions during single word reading. In contrast, the left angular gyrus is functionally disconnected from these regions in men with persistent developmental dyslexia, suggesting that the anatomical disconnection of the left angular gyrus from other brain regions that are part of the ''normal'' brain reading network in many cases of acquired alexia is mirrored by its functional disconnection in developmental dyslexia.

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“…For these animals, we simply subtracted a background value measured in the dorsal striatum to correct for background (ensuring that the relationships we obtained in the first analysis were not an artifact of the residualization). The values were then entered into the original equation (i.e., they were multiplied through the weights of the original equation) to obtain predicted behavioral values, and the predicted versus observed correlation was evaluated accordingly (Horwitz et al, 1992): the Pearson's r value was converted to Fisher's z value (Fisher's r-z transformation) using the formula:…”

Section: Predictive Validity Analysismentioning

confidence: 99%

Central Oxytocin, Vasopressin, and Corticotropin-Releasing Factor Receptor Densities in the Basal Forebrain Predict Isolation Potentiated Startle in Rats

Nair¹,

Gutman²,

Davis³

et al. 2005

J. Neurosci.

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Individual differences in resiliency to particular stressors may be mediated by specific neuropeptide receptor patterns in the brain. Here, we explored this issue by using a multivariate approach to identify brain sites in which oxytocin (OTR), vasopressin (V1aR), and corticotropin-releasing factor type 1 (CRF1) or type 2 receptor binding covaried with a measure of isolation-induced anxiety: isolation potentiated startle (IPS). Partial least squares (PLS) analysis identified three binding sites, the shell of the nucleus accumbens (AccSh), lateral bed nucleus of the stria terminalis, and intermediate zone of the lateral septum, in which CRF1, V1aR, and OTR receptors, respectively, covaried with IPS. Multiple regression analysis demonstrated that the three binding sites accounted for more of the variation in IPS as a linear combination than when considered individually. Using the same multiple regression model, the linear combination of the same three binding sites/peptide receptors measured in a new group of animals successfully predicted their IPS values. There were no differences in binding between grouped and isolated animals, suggesting that the patterns are trait effects rather than a consequence of isolation. Based on the finding that CRF1 receptors in the AccSh were positively correlated with IPS, we infused CRF directly into the AccSh and found that it significantly potentiated startle after a short isolation period but not under grouped conditions. This result directly supported the predictions made by the combined PLS/regression approach. These results suggest that the integrated activity of neuropeptide systems mediating both social behavior and anxiety underlie IPS.

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Covariance Analysis of Functional Interactions in the Brain Using Metabolic and Blood Flow Data

Cited by 42 publications

References 61 publications

Language Processing Modulated by Literacy: A Network Analysis of Verbal Repetition in Literate and Illiterate Subjects

Language Processing Modulated by Literacy: A Network Analysis of Verbal Repetition in Literate and Illiterate Subjects

Functional connectivity of the angular gyrus in normal reading and dyslexia

Central Oxytocin, Vasopressin, and Corticotropin-Releasing Factor Receptor Densities in the Basal Forebrain Predict Isolation Potentiated Startle in Rats

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