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Kveraga K, Ghuman A, Kassam K, Aminoff E, Hamalainen M, Chaumon M, Bar M. Early activation of contextual associations during object recognition. J Vis 2010. [DOI: 10.1167/10.7.1192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bar M. Contextual associations in the brain: past, present and future. J Vis 2010. [DOI: 10.1167/10.7.981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Thomas C, Kveraga K, Bar M. The basis of global and local visual perception revealed by psychophysical 'lesions'. J Vis 2010. [DOI: 10.1167/10.7.972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Aminoff E, Bar M. Frequency of exposure modulates cortical activity in the contextual associations network. J Vis 2010. [DOI: 10.1167/10.7.744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Skoloudik D, Herzig R, Fadrna T, Bar M, Hradilek P, Roubec M, Jelinkova M, Sanak D, Kral M, Chmelova J, Herman M, Langova K, Kanovsky P. Distal enlargement of the optic nerve sheath in the hyperacute stage of intracerebral haemorrhage. Br J Ophthalmol 2010; 95:217-21. [DOI: 10.1136/bjo.2009.172890] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Kveraga K, Boshyan J, Bar M. Magnocellular contributions to top-down-facilitation of object recognition. J Vis 2010. [DOI: 10.1167/6.6.813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Gronau N, Neta M, Bar M. Visual contextual representations bind semantic and spatial associations. J Vis 2010. [DOI: 10.1167/6.6.618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Zago L, Bar M. THE RISE AND FALL OF VISUAL PRIMING. J Vis 2010. [DOI: 10.1167/3.9.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Aminoff E, Vaitsou C, Schacter D, Bar M. The cortical network processing contextual, semantic and physical relationships between visual objects. J Vis 2010. [DOI: 10.1167/2.7.698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bar M, Aminoff E. Contextual processing of visual objects in the brain. J Vis 2010. [DOI: 10.1167/2.7.410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bar M, Vaitsou C, Schacter D. Gradual activation of visual associations. J Vis 2010. [DOI: 10.1167/1.3.473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Gat-Yablonski G, Lazar L, Bar M, de Vries L, Weintrob N, Phillip M. Growth without growth hormone and similar dysmorphic features in three patients with sporadic combined pituitary hormone deficiencies. HORMONE RESEARCH 2009; 72:302-9. [PMID: 19844116 DOI: 10.1159/000245932] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2008] [Accepted: 01/15/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Mutations in the HESX1 gene are associated with a broad spectrum of phenotypes: septo-optic dysplasia, midline defects, pituitary abnormalities with consequent hypopituitarism, isolated growth hormone (GH) deficiency or combined pituitary hormone deficiencies (CPHD). This study examined the prevalence of mutations in the HESX1 gene in patients with CPHD. PATIENTS/METHODS Sixty patients with sporadic CPHD without septo-optic dysplasia were screened for mutations in HESX1. RESULTS Three patients were found to be heterozygous for the same Asn125Ser variant in the HESX1 gene. In all 3, panhypopituitarism was presented in the neonatal period, manifested by severe hypoglycemia and neonatal jaundice in 2 patients and respiratory distress in 1. Remarkable findings from physical examination included coarse face; prominent, large, low-set ears; and skeletal abnormalities. Magnetic resonance imaging, performed in 2 patients, revealed a hypoplastic anterior and ectopic posterior pituitary without other midline anomalies. Despite persistent GH deficiency and undetectable levels of insulin-like growth factor 1, all patients had normal linear growth along the 10-25th percentile without GH therapy. CONCLUSION The present study expands the clinical picture of HESX1 mutations by demonstrating that patients heterozygous for Asn125Ser may have a severe endocrinologic and neuroradiologic phenotype and similar dysmorphic features appearing very early in life.
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Bar M, Skoloudik D, Roubec M. PO04-MO-10 Post-stroke depression: a one year prospective follow-up study. J Neurol Sci 2009. [DOI: 10.1016/s0022-510x(09)70658-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Skoloudik D, Herzig R, Fadrna T, Bar M, Zapletal O, Blatny J, Langova K, Kanovsky P, Kral M. FP19-TU-01 Sono-thrombolytic activation of the fibrinolytic system in acute stroke patients using a diagnostic 1–4MHz transcranial probe. J Neurol Sci 2009. [DOI: 10.1016/s0022-510x(09)70362-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Aminoff E, Gronau N, Bar M. The Parahippocampal Cortex Mediates Spatial and Nonspatial Associations. Cereb Cortex 2006; 17:1493-503. [PMID: 16990438 DOI: 10.1093/cercor/bhl078] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The parahippocampal cortex (PHC) has been implicated in the processing of place-related information. It has also been implicated in episodic memory, even for items that are not related to unique places. How could the same cortical region mediate such seemingly different cognitive processes? Both processes rely on contextual associations, and we therefore propose that the PHC should be viewed not as exclusively dedicated for analyzing place-related information, or as solely processing episodic memories, but instead as more generally playing a central role in contextual associative processing. To test this proposal, we created a novel learning paradigm to form new associations among meaningless visual patterns. These new associations were created to emulate either spatial or nonspatial contexts. Both spatial and nonspatial associations activated the PHC more than noncontextual items. Moreover, items from spatial contexts activated the posterior part of the PHC, whereas items from nonspatial contexts activated the anterior PHC. Therefore, we show that the PHC plays a role of processing contextual associations in general, and that these associations are not restricted to spatial information. By modifying the existing view of the PHC function accordingly, the seemingly contradicting processes that activate it can be reconciled under one overarching framework.
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Bar M, Kassam KS, Ghuman AS, Boshyan J, Schmid AM, Schmidt AM, Dale AM, Hämäläinen MS, Marinkovic K, Schacter DL, Rosen BR, Halgren E. Top-down facilitation of visual recognition. Proc Natl Acad Sci U S A 2006; 103:449-54. [PMID: 16407167 PMCID: PMC1326160 DOI: 10.1073/pnas.0507062103] [Citation(s) in RCA: 944] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Accepted: 11/23/2005] [Indexed: 11/18/2022] Open
Abstract
Cortical analysis related to visual object recognition is traditionally thought to propagate serially along a bottom-up hierarchy of ventral areas. Recent proposals gradually promote the role of top-down processing in recognition, but how such facilitation is triggered remains a puzzle. We tested a specific model, proposing that low spatial frequencies facilitate visual object recognition by initiating top-down processes projected from orbitofrontal to visual cortex. The present study combined magnetoencephalography, which has superior temporal resolution, functional magnetic resonance imaging, and a behavioral task that yields successful recognition with stimulus repetitions. Object recognition elicited differential activity that developed in the left orbitofrontal cortex 50 ms earlier than it did in recognition-related areas in the temporal cortex. This early orbitofrontal activity was directly modulated by the presence of low spatial frequencies in the image. Taken together, the dynamics we revealed provide strong support for the proposal of how top-down facilitation of object recognition is initiated, and our observations are used to derive predictions for future research.
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Gronau N, Neta M, Bar M. Combined and dissociable effects of spatial and semantic contextual information on visual object recognition. J Vis 2005. [DOI: 10.1167/5.8.853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bar M, Aminoff E, Boshyan J, Fenske M, Gronauo N, Kassam K. The contribution of context to visual object recognition. J Vis 2005. [DOI: 10.1167/5.8.88] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Fenske MJ, Boshyan J, Bar M. Can a gun prime a hairbrush? The "initial guesses" that drive top-down contextual facilitation of object recognition. J Vis 2005. [DOI: 10.1167/5.8.851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Boshyan J, Fenske M, Aminoff E, Bar M. Cortical manifestations of context-related facilitation of visual object recognition. J Vis 2005. [DOI: 10.1167/5.8.852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Aminoff EM, Gronau N, Bar M. The parahippocampal cortex mediates both spatial and non-spatial associative processing. J Vis 2005. [DOI: 10.1167/5.8.907] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Ghuman AS, Kassam KS, Boshyan H, Bar M. Cortical interactions in top-down facilitation of visual object recognition through low spatial frequencies. J Vis 2005. [DOI: 10.1167/5.8.89] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Bar M. Viewpoint dependency in visual object recognition does not necessarily imply viewer-centered representation. J Cogn Neurosci 2001; 13:793-9. [PMID: 11564323 DOI: 10.1162/08989290152541458] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The nature of visual object representation in the brain is the subject of a prolonged debate. One set of theories asserts that objects are represented by their structural description and the representation is "object-centered." Theories from the other side of the debate suggest that humans store multiple "snapshots" for each object, depicting it as seen under various conditions, and the representation is therefore "viewer-centered." The principal tool that has been used to support and criticize each of these hypotheses is subjects' performance in recognizing objects under novel viewing conditions. For example, if subjects take more time in recognizing an object from an unfamiliar viewpoint, it is common to claim that the representation of that object is viewpoint-dependent and therefore viewer-centered. It is suggested here, however, that performance cost in recognition of objects under novel conditions may be misleading when studying the nature of object representation. Specifically, it is argued that viewpoint-dependent performance is not necessarily an indication of viewer-centered representation. An account for the neural basis of perceptual priming is first provided. In light of this account, it is conceivable that viewpoint dependency reflects the utilization of neural paths with different levels of sensitivity en route to the same representation, rather than the existence of viewpoint-specific representations. New experimental paradigms are required to study the validity of the viewer-centered approach.
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Gidoni D, Bar M, Gilboa N. FLP/FRT-mediated restoration of normal phenotypes and clonal sectors formation in rolC transgenic tobacco. Transgenic Res 2001; 10:317-28. [PMID: 11592711 DOI: 10.1023/a:1016603627254] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Site-specific recombination systems have been shown to excise transgene DNA sequences positioned between their cognate target sites, and thus be used to generate clonal sectors in transgenic plants. Here we characterized clonal sectors derived from genetic reversion of rolC (A. rhizogenes)--induced vegetative and reproductive phenotypes, mediated by FLP recombinase from S. cerevisiae, in tobacco. The constitutive expression of rolC induces pleiotropic effects including reduced apical dominance and plant height, lanceolate and pale green leaves and small, male-sterile flowers. Two transgenic male-sterile tobacco lines (N. tabacum, Samsun NN) expressing a 35sP-rolC gene construct flanked by two FRT (FLP recombinase target) sites, were cross-pollinated with pollen from a constitutive 35sP-FLP expressing line. Three main phenotypes were generated in result of recombinase-mediated excision of the 35sP-rolC locus in the F1 (FLP x FRT-35sP-rolC-FRT) hybrid progenies: (a) restoration of male fertility, associated with reversion to normal leaf phenotypes prior to flower bud formation, (b) development of normal and fertile lateral shoot sectors on the background of rolC-type plants, (c) restoration of partially fertile flowers, associated with display of peripheral normal leaf sectors surrounding rolC-type inner-leaf tissues, consistent with periclinal chimeras. These results, supported by DNA molecular analysis, indicate that site-specific recombination might be used as a relatively efficient tool for generation of transgenic periclinal chimeric plants.
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Vogels R, Biederman I, Bar M, Lorincz A. Inferior temporal neurons show greater sensitivity to nonaccidental than to metric shape differences. J Cogn Neurosci 2001; 13:444-53. [PMID: 11388918 DOI: 10.1162/08989290152001871] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
It has long been known that macaque inferior temporal (IT) neurons tend to fire more strongly to some shapes than to others, and that different IT neurons can show markedly different shape preferences. Beyond the discovery that these preferences can be elicited by features of moderate complexity, no general principle of (nonface) object recognition had emerged by which this enormous variation in selectivity could be understood. Psychophysical, as well as computational work, suggests that one such principle is the difference between viewpoint-invariant, nonaccidental (NAP) and view-dependent, metric shape properties (MPs). We measured the responses of single IT neurons to objects differing in either a NAP (namely, a change in a geon) or an MP of a single part, shown at two orientations in depth. The cells were more sensitive to changes in NAPs than in MPs, even though the image variation (as assessed by wavelet-like measures) produced by the former were smaller than the latter. The magnitude of the response modulation from the rotation itself was, on average, similar to that produced by the NAP differences, although the image changes from the rotation were much greater than that produced by NAP differences. Multidimensional scaling of the neural responses indicated a NAP/MP dimension, independent of an orientation dimension. The present results thus demonstrate that a significant portion of the neural code of IT cells represents differences in NAPs rather than MPs. This code may enable immediate recognition of novel objects at new views.
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