Visual spatial resolution is limited by factors ranging from optics to neuronal filters in the visual cortex, but it is not known to what extent it is also limited by the resolving power of attention. To investigate this, we studied adaptation to lines of specific orientation, a process that occurs in primary visual cortex. When a single grating is presented in the periphery of the visual field, human observers are aware of its orientation, but when it is flanked by other similar gratings ('crowding'), its orientation becomes impossible to discern. Nevertheless, we show that orientation-specific adaptation is not affected by crowding, implying that spatial resolution is limited by an attentional filter acting beyond the primary visual cortex. Consistent with this, we find that attentional resolution is greater in the lower than in the upper visual field, whereas there is no corresponding asymmetry in the primary visual cortex. We suggest that the attentional filter acts in one or more higher visual cortical areas to restrict the availability of visual information to conscious awareness.

Familiar and recognizable stimuli enjoy an advantage of predominance during binocular rivalry, and this advantage is usually attributed to their enhanced processing during the dominant phase. However, do familiar and recognizable stimuli have an advantage in breaking suppression? Test images were gradually introduced to one eye to compete against a standard high-contrast dynamic noise pattern presented to the other eye. Results showed that an upright face took less time than an upside-down face to gain dominance against the identical suppression noise. Results also showed that for Chinese readers, Chinese characters were faster to gain dominance than Hebrew words, whereas for Hebrew readers, the reverse was true. These results suggest that familiar and recognizable information, even when suppressed and invisible, is processed differently from unfamiliar information. Apparently, high-level information about visual form does contribute to the strength of a stimulus during its suppressed phase.

Representing magnitude information in various dimensions, including space, quantity, and time, is an important function of the human brain. Many previous studies reported that numerical and spatial magnitudes could be mutually influenced through a "mental number line". In this study, we address the question of whether magnitudes in nontemporal dimensions and magnitudes in time are represented independently or not. Observers judged the duration of the stimuli while four types of nontemporal magnitude information, including number of dots, size of open squares, luminance of solid squares, and numeric value of digits, were manipulated in Stroop-like paradigms. Results revealed that stimuli with larger magnitudes in these nontemporal dimensions were judged to be temporally longer. This observation supports the idea that magnitudes in temporal and nontemporal dimensions are not independent and implies the existence of generalized and abstract components in the magnitude representations.

The primate visual system is believed to comprise two main pathways: a ventral pathway for conscious perception and a dorsal pathway that can process visual information and guide action without accompanying conscious knowledge. Evidence for this theory has come primarily from studies of neurological patients and animals. Using fMRI, we show here that even though observers are completely unaware of test object images owing to interocular suppression, their dorsal cortical areas demonstrate substantial activity for different types of visual objects, with stronger responses to images of tools than of human faces. This result also suggests that in binocular rivalry, substantial information in the suppressed eye can escape the interocular suppression and reach dorsal cortex.

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Perceiving faces is critical for social interaction. Evidence suggests that different neural pathways may be responsible for processing face identity and expression information. By using functional magnetic resonance imaging (fMRI), we measured brain responses when observers viewed neutral, fearful, and scrambled faces, either visible or rendered invisible through interocular suppression. The right fusiform face area (FFA), the right superior temporal sulcus (STS), and the amygdala responded strongly to visible faces. However, when face images became invisible, activity in FFA to both neutral and fearful faces was much reduced, although still measurable; activity in the STS was robust only to invisible fearful faces but not to neutral faces. Activity in the amygdala was equally strong in both the visible and invisible conditions to fearful faces but much weaker in the invisible condition for the neutral faces. In the invisible condition, amygdala activity was highly correlated with that of the STS but not with FFA. The results in the invisible condition support the existence of dissociable neural systems specialized for processing facial identity and expression information. When images are invisible, cortical responses may reflect primarily feed-forward visual-information processing and thus allow us to reveal the distinct functions of FFA and STS.

The capacity to fix nitrogen is widely distributed in phyla of Bacteria and Archaea but has long been considered to be absent from the Pseudomonas genus. We report here the complete genome sequencing of nitrogen-fixing root-associated Pseudomonas stutzeri A1501. The genome consists of a single circular chromosome with 4,567,418 bp. Comparative genomics revealed that, among 4,146 protein-encoding genes, 1,977 have orthologs in each of the five other Pseudomonas representative species sequenced to date. The genome contains genes involved in broad utilization of carbon sources, nitrogen fixation, denitrification, degradation of aromatic compounds, biosynthesis of polyhydroxybutyrate, multiple pathways of protection against environmental stress, and other functions that presumably give A1501 an advantage in root colonization. Genetic information on synthesis, maturation, and functioning of nitrogenase is clustered in a 49-kb island, suggesting that this property was acquired by lateral gene transfer. New genes required for the nitrogen fixation process have been identified within the nif island. The genome sequence offers the genetic basis for further study of the evolution of the nitrogen fixation property and identification of rhizosphere competence traits required in the interaction with host plants; moreover, it opens up new perspectives for wider application of root-associated diazotrophs in sustainable agriculture.genome sequencing ͉ root-associated diazotroph

Human observers are constantly bombarded with a vast amount of information. Selective attention helps us to quickly process what is important while ignoring the irrelevant. In this study, we demonstrate that information that has not entered observers' consciousness, such as interocularly suppressed (invisible) erotic pictures, can direct the distribution of spatial attention. Furthermore, invisible erotic information can either attract or repel observers' spatial attention depending on their gender and sexual orientation. While unaware of the suppressed pictures, heterosexual males' attention was attracted to invisible female nudes, heterosexual females' attention was attracted to invisible male nudes, gay males behaved similarly to heterosexual females, and gay͞bisexual females performed in-between heterosexual males and females.awareness ͉ interocular suppression ͉ attention S alient events in a visual scene can attract visual attention and subsequently enhance information processing at the attended location (1-3). Intuitively, in order for a ''cue'' to attract visual spatial attention, the ''cue'' needs to be perceived by the observer. However, it makes ecological and evolutionary sense if important events can influence observers' spatial attention even before the observer becomes aware of the event. Recent studies have shown that subliminal presentation of emotional stimuli can modulate activity of the amygdala (4, 5), a subcortical nucleus that is centrally involved in emotional information processing. Emotionally salient information was also shown to receive enhanced processing under limited attention, such as during the attentional blink, with the amygdala playing a critical role (6). One natural question is whether activation of the emotional system also directs observers' attention to the stimulus in the absence of awareness. For example, if highly attractive, aversive, or threatening information comes from one side of the visual field and it subsequently activates emotional brain systems without awareness, will this lead to a reorienting of spatial attention? Activation of the amygdala may or may not carry specific spatial information. However, what is the value of processing important information if it does not lead to specific changes in observers' attentional states and preparation for action?To investigate the ability of invisible information to guide spatial attention, we combined two paradigms: interocular suppression to render stimuli invisible (5, 7, 8) and a modified version of the Posner cuing paradigm to test the effect of spatially directed attention (1-3). In the interocular suppression paradigm, a pair of highcontrast dynamic noise patches are presented to both sides of a fixation point in one eye, and a test picture and its scrambled control are presented to the fellow eye in spatial locations corresponding to the noise patches. Because of strong interocular suppression, the intact meaningful image and its scrambled control remain invisible for the period they are presented. If the suppr...