Ancestral Asian source(s) of new world Y-chromosome founder haplotypes.
(1/669)Haplotypes constructed from Y-chromosome markers were used to trace the origins of Native Americans. Our sample consisted of 2,198 males from 60 global populations, including 19 Native American and 15 indigenous North Asian groups. A set of 12 biallelic polymorphisms gave rise to 14 unique Y-chromosome haplotypes that were unevenly distributed among the populations. Combining multiallelic variation at two Y-linked microsatellites (DYS19 and DXYS156Y) with the unique haplotypes results in a total of 95 combination haplotypes. Contra previous findings based on Y- chromosome data, our new results suggest the possibility of more than one Native American paternal founder haplotype. We postulate that, of the nine unique haplotypes found in Native Americans, haplotypes 1C and 1F are the best candidates for major New World founder haplotypes, whereas haplotypes 1B, 1I, and 1U may either be founder haplotypes and/or have arrived in the New World via recent admixture. Two of the other four haplotypes (YAP+ haplotypes 4 and 5) are probably present because of post-Columbian admixture, whereas haplotype 1G may have originated in the New World, and the Old World source of the final New World haplotype (1D) remains unresolved. The contrasting distribution patterns of the two major candidate founder haplotypes in Asia and the New World, as well as the results of a nested cladistic analysis, suggest the possibility of more than one paternal migration from the general region of Lake Baikal to the Americas. (+info)
Is grammar special?
(2/669)Recent studies of children with developmental disorders provide striking insights into the nature of language. These studies suggest that, although much of language arises from more general cognitive capacities, certain aspects of grammar have an autonomous psychological and neural basis. (+info)
Segregating the functions of human hippocampus.
(3/669)It is now accepted that hippocampal lesions impair episodic memory. However, the precise functional role of the hippocampus in episodic memory remains elusive. Recent functional imaging data implicate the hippocampus in processing novelty, a finding supported by human in vivo recordings and event-related potential studies. Here we measure hippocampal responses to novelty, using functional MRI (fMRI), during an item-learning paradigm generated from an artificial grammar system. During learning, two distinct types of novelty were periodically introduced: perceptual novelty, pertaining to the physical characteristics of stimuli (in this case visual characteristics), and exemplar novelty, reflecting semantic characteristics of stimuli (in this case grammatical status within a rule system). We demonstrate a left anterior hippocampal response to both types of novelty and adaptation of these responses with stimulus familiarity. By contrast to these novelty effects, we also show bilateral posterior hippocampal responses with increasing exemplar familiarity. These results suggest a functional dissociation within the hippocampus with respect to the relative familiarity of study items. Neural responses in anterior hippocampus index generic novelty, whereas posterior hippocampal responses index familiarity to stimuli that have behavioral relevance (i.e., only exemplar familiarity). These findings add to recent evidence for functional segregation within the human hippocampus during learning. (+info)
Turfing: patients in the balance.
(4/669)OBJECTIVE: To examine the language of "turfing," a ubiquitous term applied to some transfers of patients between physicians, in order to reveal aspects of the ideology of internal medicine residency. SETTING: Academic internal medicine training program. MEASUREMENTS: Using direct observation and a focus group, we collected audiotapes of medical residents' discussions of turfing. These data were analyzed using interpretive and conversation analytic methods. The focus group was used both to validate and to further elaborate a schematic conceptual framework for turfing. MAIN RESULTS: The decision to call a patient "turfed" depends on the balance of the values of effectiveness of therapy, continuity of care, and power. For example, if the receiving physician cannot provide a more effective therapy than can the transferring physician, medical residents consider the transfer inappropriate, and call the patient a turf. With appropriate transfers, these residents see their service as honorable, but with turfs, residents talk about the irresponsibility of transferring physicians, burdens of service, abuse, and powerlessness. CONCLUSIONS: Internal medicine residents can feel angry and frustrated about receiving patients perceived to be rejected by other doctors, and powerless to prevent the transfer of those patients for whom they may have no effective treatment or continuous relationship. This study has implications for further exploration of how the relationships between physicians may uphold or conflict with the underlying moral tenets of the medical profession. (+info)
Away with words: commentary on the Atlan-Cohen essay 'Immune information, self-organization and meaning'.
(5/669)Drawing on metaphors from linguistics and information theory, Atlan and Cohen challenge us to take a very different view of the immune system, one that engages in constant chatter among the constituents and allows the immune system to arrive at a decision about what to, and not to, destroy. Our commentary responds to this challenge and points out many logical biological flaws in their view. We seem to agree that specificity is important, and that there is some kind of somatic selection process at work to distinguish self from non-self. Our analysis of models depends on the basis of how self and non-self are separated. There are only two possibilities, time or space; and space-based models are all but ruled out. There are two major kinds of time-based model, one based on the time taken for an organism to develop from embryo to adult, the other based on the time taken for a cell to differentiate from one state to another. With so many ambiguities in the metaphors and so little attention to mechanism, the Atlan and Cohen challenge is, we suspect, based on time measured in cell differentiation units. They also make the common mistake of assuming repertoires that are transcendental in size (>10(10)), making it impossible to have a functional immune system in animals smaller than a rabbit--a feature that does not instill confidence in the biological relevance of such models. (+info)
The evolution of language.
(6/669)The emergence of language was a defining moment in the evolution of modern humans. It was an innovation that changed radically the character of human society. Here, we provide an approach to language evolution based on evolutionary game theory. We explore the ways in which protolanguages can evolve in a nonlinguistic society and how specific signals can become associated with specific objects. We assume that early in the evolution of language, errors in signaling and perception would be common. We model the probability of misunderstanding a signal and show that this limits the number of objects that can be described by a protolanguage. This "error limit" is not overcome by employing more sounds but by combining a small set of more easily distinguishable sounds into words. The process of "word formation" enables a language to encode an essentially unlimited number of objects. Next, we analyze how words can be combined into sentences and specify the conditions for the evolution of very simple grammatical rules. We argue that grammar originated as a simplified rule system that evolved by natural selection to reduce mistakes in communication. Our theory provides a systematic approach for thinking about the origin and evolution of human language. (+info)
Linguistic threat activates the human amygdala.
(7/669)Studies in animals demonstrate a crucial role for the amygdala in emotional and social behavior, especially as related to fear and aggression. Whereas lesion and functional-imaging studies in humans indicate the amygdala's participation in assessing the significance of nonverbal as well as paralinguistic cues, direct evidence for its role in the emotional processing of linguistic cues is lacking. In this study, we use a modified Stroop task along with a high-sensitivity neuroimaging technique to target the neural substrate engaged specifically when processing linguistic threat. Healthy volunteer subjects were instructed to name the color of words of either threat or neutral valence, presented in different color fonts, while neural activity was measured by using H(2)(15)O positron-emission tomography. Bilateral amygdalar activation was significantly greater during color naming of threat words than during color naming of neutral words. Associated activations were also noted in sensory-evaluative and motor-planning areas of the brain. Thus, our results demonstrate the amygdala's role in the processing of danger elicited by language. In addition, the results reinforce the amygdala's role in the modulation of the perception of, and response to, emotionally salient stimuli. The current study further suggests conservation of phylogenetically older mechanisms of emotional evaluation in the context of more recently evolved linguistic function. (+info)
Model-based semantic dictionaries for medical language understanding.
(8/669)Semantic dictionaries are emerging as a major cornerstone towards achieving sound natural language understanding. Indeed, they constitute the main bridge between words and conceptual entities that reflect their meanings. Nowadays, more and more wide-coverage lexical dictionaries are electronically available in the public domain. However, associating a semantic content with lexical entries is not a straightforward task as it is subordinate to the existence of a fine-grained concept model of the treated domain. This paper presents the benefits and pitfalls in building and maintaining multilingual dictionaries, the semantics of which is directly established on an existing concept model. Concrete cases, handled through the GALEN-IN-USE project, illustrate the use of such semantic dictionaries for the analysis and generation of multilingual surgical procedures. (+info)