SCIENCE'S COMPASS en.B.R.Rosen. .6 22M eider.K.Ke J.V.Haxby 23. 6.608 器的 ger me 34. nt a 26E Exp.Psycho et al (1998 nd M. r to tas nd in Goldman-Rakic c N 260.1955(1993) t and r a hey may 2 G 3(193 976 189.66 ,109 d P. (5) by Rain 31. Acad the A Vogt.A.K lo 118 52 (10 to the n of thi Enhance your AAAS membership with the Science online advantage. Sciencee Science ONLINE Full text Science and news artices with hyperlinks from citation eNOW-succinct.daly bricfines.of the ho alsicnmifc,mcdcelandrehpolkeg ■Science's Next Wave ch Alerts-snds s-miail akrt svcry e's Professional Network-lists hun ds of iob e itsnopmoirnoraiomfiomtcwoidslkad 月\AeA96 O TH www.sciencemag org SCIENCE VOL 283 12 MARCH 1999 166111. T. Shallice, From Neuropsychology to Mental Struc￾ture (MIT Press, Cambridge, MA, 1988). 12. None of the cited item-recognition studies found activation in DLPFC. However, a recent item-recog￾nition experiment found DLPFC activation with a memory load of six items compared with three items, which suggests a role for DLPFC with larger memory loads (B. Rypma, V. Prabhakaran, J. E. Desmond, Neu￾roimage, in press). Follow-up work suggests that the role of DLPFC in this task is to mediate executive processes during encoding of the larger loads (M. D’Esposito, personal communication). 13. E. Awh et al., Psychol. Sci. 7, 125 (1996). 14. J. D. Cohen et al., Hum. Brain Mapp. 1, 293 (1994). 15. E. H. Schumacher et al., Neuroimage 3, 79 (1996); E. E. Smith, J. Jonides, R. A. Koeppe, Cereb. Cortex 6, 11 (1996); T. S. Braver, J. D. Cohen, J. Jonides, E. E. Smith, D. C. Noll, Neuroimage 5, 49 (1997); J. D. Cohen et al., Nature 386, 604 (1997); J. Jonides et al., J. Cognit. Neurosci. 9, 462(1997). 16. J. A. Fiez et al., J. Neurosci. 16, 808 (1996); J. Jonides et al., ibid. 18, 5026 (1998). 17. F. A. Wilson, S. P. Scalaidhe, P. S. Goldman-Rakic, Science 260, 1955 (1993). 18. There is currently some controversy about the degree of separation of object and spatial regions in PFC in nonhuman primates. Recent findings indicate that dorsal or ventral regions can contain neurons that process either spatial or object information or both [S. C. Rao, G. Rainer, E. K. Miller, Science 276, 821 (1997); G. Rainer, W. F. Asaad, E. K. Miller, Proc. Natl. Acad. Sci. U.S.A. 95, 15008 (1998)]. However, even these studies find some neural segregation—a sizable proportion of neurons tested by Rainer et al. are selective only for location, and these neurons pre￾dominate in posterior locations. 19. E. E. Smith et al., J. Cogn. Neurosci. 7, 337 (1995); G. B. McCarthy et al., Proc. Natl. Acad. Sci. U.S.A. 91, 8690 (1994); S. M. Courtney, L. G. Ungerleider, K. Keil, Cereb. Cortex 6, 39 (1996). 20. A. M. Owen, A. C. Evans, M. Petrides, Cereb. Cortex. 6, 31 (1996). 21. I. Faillenot, H. Sakata, N. Costes, Neuroreport 8, 859 (1997); A. M. Owen et al., Proc. Natl. Acad. Sci. U.S.A. 95, 7721 (1998). 22. M. Courtney, L. G. Ungerleider, K. Keil, J. V. Haxby, Nature 386, 608 (1997). 23. S. M. Courtney, L. Petit, J. M. Maisog, L. G. Ungerlei￾der, J. V. Haxby, Science 279, 1347 (1998). 24. J. Jonides et al., Nature 363, 623 (1993); P. A. Reuter￾Lorenz et al., in press; references cited in (19, 21). 25. L. G. Ungerleider, S. M. Courtney, J. V. Haxby, Proc. Natl. Acad. Sci. U.S.A. 95, 883 (1998). 26. E. Awh, J. Jonides, P. A. Reuter-Lorenz, J. Exp. Psychol. Hum. Percept. Perform. 24, 780 (1998). 27. E. Awh and J. Jonides, in The Attentive Brain, R. Parasurama, Ed. (MIT Press, Cambridge, MA, 1997), pp. 353–380. 28. Two other recent meta-analyses of neuroimaging studies of working memory also found evidence that PFC is organized by storage versus executive process￾es [M. D’Esposito et al., Cogn. Brain Res. 7, 1 (1998); A. M. Owen, Eur. J. Neurosci. 9, 1329 (1997)]. How￾ever, neither of these meta-analyses found evidence that PFC was organized by modality. There are at least two reasons for this discrepancy from the present analyses. Neither of the previous meta-anal￾yses focused on verbal storage or included recent fMRI studies that isolate delay-period activity and that provide relatively strong evidence for a differ￾ence between spatial and object storage (22, 23). 29. J. R. Stroop, J. Exp. Psychol. 18, 643 (1935). 30. F. N. Dyer, Mem. Cogn. 1, 106 (1973); J. D. Cohen, K. Dunbar, J. L. McClelland, Psychol. Rev. 97, 332 (1990); C. M. Macleod, Psychol. Bull. 109, 163 (1991). 31. J. V. Pardo, P. J. Pardo, K. W. Janer, Proc. Natl. Acad. Sci. U.S.A. 87, 256 (1990); C. J. Bench et al., Neuro￾psychologia 31, 907 (1993); C. S. Carter, M. Mintun, J. D. Cohen, Neuroimage 2, 264 (1995); M. S. George et al., J. Neuropsychol. Clin. Neurosci. 9, 55 (1997); S. F. Taylor, S. Kornblum, E. J. Lauber, Neuroimage 6, 81 (1997); S. W. Derbyshire, B. A. Vogt, A. K. 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Attention and inhibition may also be involved in self-ordering tasks, such as the following: on each series of trials, a set of forms is presented in random positions, and participants must point to a form they have not selected on a previous trial in that series. This task activates the anterior cingulate and DLPFC, similar to tasks that involve attention and inhibition [M. Petrides, B. Alivisatos, A. C. Evans, Proc. Natl. Acad. Sci. U.S.A. 90, 873 (1993)]. Some researchers have proposed that self-ordering tasks reflect the executive process of monitoring, but alternatively they may involve an appreciable working memory load and some inhibition, either of which may cause the frontal activations. 38. A. Spector and I. Biederman, Am. J. Psychol. 89, 669 (1976). 39. M. D’Esposito et al., Nature 378, 279 (1995). 40. J. Talairach and P. Tournoux, A Co-Planar Stereotaxic Atlas of the Human Brain: An Approach to Medical Cerebral Imaging (Thieme, New York, 1988). 41. J. A. Sweeney et al., J. Neurophysiol. 75, 454 (1996). 42. Supported by grants from the National Institute on Aging and the Office of Naval Research. We are indebted to the members of our laboratory for dis￾cussion of these issues and to D. Badre for his sub￾stantial contributions to the preparation of this manuscript. S CIENCE ’ S C OMPASS www.sciencemag.org SCIENCE VOL 283 12 MARCH 1999 1661