Visual and linguistic semantic representations are aligned at the border of human visual cortex.

Semantic information in the human brain is organized into multiple networks, but the fine-grain relationships between them are poorly understood. In this study, we compared semantic maps obtained from two functional magnetic resonance imaging experiments in the same participants: one that used silent movies as stimuli and another that used narrative stories. Movies evoked activity from a network of modality-specific, semantically selective areas in visual cortex. Stories evoked activity from another network of semantically selective areas immediately anterior to visual cortex. Remarkably, the pattern of semantic selectivity in these two distinct networks corresponded along the boundary of visual cortex: for visual categories represented posterior to the boundary, the same categories were represented linguistically on the anterior side. These results suggest that these two networks are smoothly joined to form one contiguous map.

Eye movement-invariant representations in the human visual system.

During natural vision, humans make frequent eye movements but perceive a stable visual world. It is therefore likely that the human visual system contains representations of the visual world that are invariant to eye movements. Here we present an experiment designed to identify visual areas that might contain eye-movement-invariant representations. We used functional MRI to record brain activity from four human subjects who watched natural movies. In one condition subjects were required to fixate steadily, and in the other they were allowed to freely make voluntary eye movements. The movies used in each condition were identical. We reasoned that the brain activity recorded in a visual area that is invariant to eye movement should be similar under fixation and free viewing conditions. In contrast, activity in a visual area that is sensitive to eye movement should differ between fixation and free viewing. We therefore measured the similarity of brain activity across repeated presentations of the same movie within the fixation condition, and separately between the fixation and free viewing conditions. The ratio of these measures was used to determine which brain areas are most likely to contain eye movement-invariant representations. We found that voxels located in early visual areas are strongly affected by eye movements, while voxels in ventral temporal areas are only weakly affected by eye movements. These results suggest that the ventral temporal visual areas contain a stable representation of the visual world that is invariant to eye movements made during natural vision.

Pyrcca: Regularized Kernel Canonical Correlation Analysis in Python and Its Applications to Neuroimaging.

In this article we introduce Pyrcca, an open-source Python package for performing canonical correlation analysis (CCA). CCA is a multivariate analysis method for identifying relationships between sets of variables. Pyrcca supports CCA with or without regularization, and with or without linear, polynomial, or Gaussian kernelization. We first use an abstract example to describe Pyrcca functionality. We then demonstrate how Pyrcca can be used to analyze neuroimaging data. Specifically, we use Pyrcca to implement cross-subject comparison in a natural movie functional magnetic resonance imaging (fMRI) experiment by finding a data-driven set of functional response patterns that are similar across individuals. We validate this cross-subject comparison method in Pyrcca by predicting responses to novel natural movies across subjects. Finally, we show how Pyrcca can reveal retinotopic organization in brain responses to natural movies without the need for an explicit model.

Decoding the Semantic Content of Natural Movies from Human Brain Activity.

One crucial test for any quantitative model of the brain is to show that the model can be used to accurately decode information from evoked brain activity. Several recent neuroimaging studies have decoded the structure or semantic content of static visual images from human brain activity. Here we present a decoding algorithm that makes it possible to decode detailed information about the object and action categories present in natural movies from human brain activity signals measured by functional MRI. Decoding is accomplished using a hierarchical logistic regression (HLR) model that is based on labels that were manually assigned from the WordNet semantic taxonomy. This model makes it possible to simultaneously decode information about both specific and general categories, while respecting the relationships between them. Our results show that we can decode the presence of many object and action categories from averaged blood-oxygen level-dependent (BOLD) responses with a high degree of accuracy (area under the ROC curve > 0.9). Furthermore, we used this framework to test whether semantic relationships defined in the WordNet taxonomy are represented the same way in the human brain. This analysis showed that hierarchical relationships between general categories and atypical examples, such as organism and plant, did not seem to be reflected in representations measured by BOLD fMRI.

[SPECULAR MICROSCOPY NORMATIVE DATA: DOES PATIENT AGE HAVE AN IMPACT ON CORNEAL ENDOTHELIUM FEATURES IN ELDERLY EYES?].

INTRODUCTION: Corneal endothelium is essential for adequate corneal hydration and transparency. Age and ethnicity- related variability in endothelial properties is known. OBJECTIVES: To determine specular microscopy trends in the elderly and to provide normative data of endothelial features of the sampled cohort of the Israeli population aged 55-88 years. METHODS: This is a retrospective cross-sectional study analyzing specular microscopy data of the Israeli population aged 55-88 years and the determination of correlation of age to specular microscopy features. A comparison of endothelial properties was conducted between age-based groups: 55-64 years, 65-74 years, and 75-88 years. RESULTS: One hundred and eighty eight eyes of 188 patients, mean age 71.05 ± 7.9 years, were included; Mean Cell Density 2549.53 ± 294.71 cells/mm²; Coefficient of variation (CV) 42.12 ± 6.9%; Hexagonality (Hexa) 49.15 ± 6.62%; Central Corneal thickness (CCT) 552 ± 47 µm. A weak correlation was observed between cell density and age [r = -0.169; p = 0.02); CV, Hexa, and CCT did not show any correlation with age. Group analysis did not reveal statistically significant differences between the following age groups: 55-64 years; 65-74 years; 75-88 years CONCLUSIONS: Normative data of endothelial properties of the sampled cohort of Israeli population aged 55-88 years is provided. Age has a weak correlation with cell density. DISCUSSION AND SUMMARY: Considering the aging of the population, endothelial properties do not justify the rejection of potential donors based on age alone.

Retinotopy versus face selectivity in macaque visual cortex.

Retinotopic organization is a ubiquitous property of lower-tier visual cortical areas in human and nonhuman primates. In macaque visual cortex, the retinotopic maps extend to higher-order areas in the ventral visual pathway, including area TEO in the inferior temporal (IT) cortex. Distinct regions within IT cortex are also selective to specific object categories such as faces. Here we tested the topographic relationship between retinotopic maps and face-selective patches in macaque visual cortex using high-resolution fMRI and retinotopic face stimuli. Distinct subregions within face-selective patches showed either (1) a coarse retinotopic map of eccentricity and polar angle, (2) a retinotopic bias to a specific location of visual field, or (3) nonretinotopic selectivity. In general, regions along the lateral convexity of IT cortex showed more overlap between retinotopic maps and face selectivity, compared with regions within the STS. Thus, face patches in macaques can be subdivided into smaller patches with distinguishable retinotopic properties.

The "parahippocampal place area" responds preferentially to high spatial frequencies in humans and monkeys.

Defining the exact mechanisms by which the brain processes visual objects and scenes remains an unresolved challenge. Valuable clues to this process have emerged from the demonstration that clusters of neurons ("modules") in inferior temporal cortex apparently respond selectively to specific categories of visual stimuli, such as places/scenes. However, the higher-order "category-selective" response could also reflect specific lower-level spatial factors. Here we tested this idea in multiple functional MRI experiments, in humans and macaque monkeys, by systematically manipulating the spatial content of geometrical shapes and natural images. These tests revealed that visual spatial discontinuities (as reflected by an increased response to high spatial frequencies) selectively activate a well-known place-selective region of visual cortex (the "parahippocampal place area") in humans. In macaques, we demonstrate a homologous cortical area, and show that it also responds selectively to higher spatial frequencies. The parahippocampal place area may use such information for detecting object borders and scene details during spatial perception and navigation.

Neural correlates of semantic competition during processing of ambiguous words.

The current study investigated the neural correlates that underlie the processing of ambiguous words and the potential effects of semantic competition on that processing. Participants performed speeded lexical decisions on semantically related and unrelated prime-target pairs presented in the auditory modality. The primes were either ambiguous words (e.g., ball) or unambiguous words (e.g., athlete), and targets were either semantically related to the dominant (i.e., most frequent) meaning of the ambiguous prime word (e.g., soccer) or to the subordinate (i.e., less frequent) meaning (e.g., dance). Results showed increased activation in the bilateral inferior frontal gyrus (IFG) for ambiguous-related compared to unambiguous-related stimulus pairs, demonstrating that prefrontal areas are activated even in an implicit task where participants are not required to explicitly analyze the semantic content of the stimuli and to make an overt selection of a particular meaning based on this analysis. Additionally, increased activation was found in the left IFG and the left cingulate gyrus for subordinate meaning compared to dominant meaning conditions, suggesting that additional resources are recruited in order to resolve increased competition demands in accessing the subordinate meaning of an ambiguous word.

Parental attitude toward unaccompanied clinic visits of adolescents.

UNLABELLED: To describe parental attitudes regarding the age and the type of medical problems that are appropriate for adolescent unaccompanied visits to the clinic at an age younger than 18 years. METHODS: A structured interview was conducted with parents who visited two community clinics with their children. The questionnaire included: 1) At what age would you allow your child to visit the clinic alone? 2) What medical conditions are acceptable for unaccompanied visit at the age you stated (if lower than 18 years)? and 3) What medical conditions are not acceptable for unaccompanied visit at the age you stated (if lower than 18 years)? RESULTS: Two hundred and fifty three parents were interviewed. There was an agreement between parents from the two clinics regarding the mean age appropriate for an unaccompanied visit (mean 14.1 +/- 2.56 years for clinic A and 13.8 +/- 2.66 years for clinic B). Medical conditions most acceptable for unaccompanied visits were common cold (clinic A = 77.4%, clinic B = 70.5%), sore throat (A = 64.5%, B = 84.3%) and fever (A = 34.7%, B = 19.4%). Medical conditions most unacceptable for unaccompanied visit were: injury (clinic A = 68.5%, clinic B = 53.5%), fever (A = 37.1%, B = 42.6%) and severe illness (A = 19.4%, B=23.3%). CONCLUSIONS: most parents were willing to allow their adolescent children unaccompanied visits to the physician at an age below that stipulated by law. As unaccompanied visits are widely practiced and accepted by the public, it might be necessary to amend the law.

The role of the left inferior frontal gyrus in implicit semantic competition and selection: An event-related fMRI study.

Recent research suggests that the left inferior frontal gyrus (LIFG) plays a role in selecting semantic information from among competing alternatives. A key question remains as to whether the LIFG is engaged by the selection of semantic information only or by increased semantic competition in and of itself, especially when such competition is implicit in nature. Ambiguous words presented in a lexical context provide a means of examining whether the LIFG is recruited under conditions when contextual cues constrain selection to only the meaning appropriate to the context (e.g., coin-mint-money) or under conditions of increased competition when contextual cues do not allow for the resolution to a particular meaning (e.g., candy-mint-money). In this event-related fMRI study, an implicit task was used in which subjects made lexical (i.e., word/nonword) decisions on the third stimulus of auditorily presented triplets in conditions where the lexical context either promoted resolution toward a particular ambiguous word meaning or enhanced the competition among ambiguous word meanings. LIFG activation was observed when the context allowed for the resolution of competition and hence the selection of one meaning (e.g., coin-mint-money) but failed to emerge when competition between the meanings of an ambiguous word was unresolved by the context (e.g., candy-mint-money). In the latter case, there was a pattern of reduced activation in frontal, temporal and parietal areas. These findings demonstrate that selection or resolution of competition as opposed to increased semantic competition alone engages the LIFG. Moreover, they extend previous work in showing that the LIFG is recruited even in cases where the selection of meaning takes place implicitly.

Who accompanies a child to the office of the physician?

The arrival of a minor, unaccompanied by a parent, for a clinic visit, is challenging to the physician with legal, ethical, and practical implications. This prospective study, conducted in three community pediatric clinics, examined the relationship of accompanying persons to the minors visiting the clinics. About 90% of the 1,104 visits were with an accompanying parent, mostly a mother. Over 9% of minors, especially adolescents, arrived at the clinic unaccompanied by a parent. A regression analysis demonstrated that for each increase of one month in age there was a 2% increased chance for a visit without a parent (p < .0001). Adolescents were more likely to be among the 6% of minors, who visited the clinic alone, with a rate 0.066 per 1,000 visits in the more affluent community, compared to 0.019 and 0.016 in the middle and low income communities (p < .001). Physicians as well as parents should be made aware of the regulations regarding accompaniment of minors on a visit to the clinic. Policies regarding unaccompanied visits should take into account the risk posed by the absence of a parent versus the right of adolescents for independence and privacy.

[Breastfeeding patterns according to ethnic origin in two Well Child-Care Clinics in Beer Sheva and Ofakim].

OBJECTIVE: To determine breastfeeding patterns according to the ethnic origin of mothers of 2-year old babies in two Well Child-Care Clinics in Beer Sheva and Ofakim, Israel. METHODS: A cross-sectional study was performed including all mothers of 2-year old babies in two Well Child-Care Clinics in Beer Sheva and Ofakim. A structured interview was given to 132 mothers, which included demographic data and breast-feeding characteristics. RESULTS: A total of 106 mothers (80%) initiated and maintained breast-feeding. Mean duration of breast-feeding was 10.7 weeks (SD = 13). Women of North-African ethnicity were less likely to maintain breast-feeding (8.8 +/- 21.1) as compared to mothers of Iranian/Iraqi/Turkish descent (29.7 +/- 39.8) (p < 0.05). Mean duration of breast-feeding among mothers who worked out of their house was significantly longer as compared to housewives (7.7 +/- 14.5 vs. 16.9 +/- 29.3; p = 0.05). These women had a higher level of education as compared to the housewives (14.0 +/- 2.7 years vs. 11.6+/- 1.4 years; p < 0.01). Mothers of three children were less likely to maintain breast-feeding as compared to mothers of two children (8.8 +/- 10.6 weeks vs. 16.1 +/- 19.7 weeks; p < 0.05). CONCLUSIONS: Special efforts in the realm of education regarding the importance of breast-feeding should be focused on mothers of North-African descent, secular women, housewives and those having three or more children. Further prospective studies should investigate the efficacy of educational programs as well as support groups regarding breast-feeding.