Evolutionary specialization in mammalian cortical structure

Changes in neocortex size were a prominent feature of mammalian brain evolution, but the implications for cortical structure, and consequently for the functional significance of such changes in overall cortical size, are poorly understood. A basic question is whether functionally differentiated cortical areas evolved independently of one another (adaptive specialization) or were allometrically constrained to co-vary tightly with the size of the whole. Here, I provide comparative evidence for adaptive specialization of cortical structure. First, the sizes of individual areas differ significantly between taxa after controlling for overall cortical size. Second, an analysis of separate visual cortical areas reveals that these exhibit statistically correlated evolution, independent of variation in nonvisual areas. Third, visual cortex size exhibits correlated evolution with peripheral visual adaptations (eye morphology and optic nerve size) and with photic niche. Thus, the evolution of mammalian cortical structure was closely associated with specialization for different sensory niches.     

Autism in infants: an update

Although autism is a disorder of very early onset, knowledge on how it is first expressed in infancy has, until recently, remained limited. In recent years new strategies of research, including prospective studies, have substantially increased our knowledge regarding autism in infants. Research findings have suggested the very early emergence of significant differences in social information processes. In addition to having important implications for research, these findings also offer new opportunities for screening and early identification and, hopefully, for improved outcome.     

Action anticipation in human infants reveals assumptions about anteroposterior body-structure and action

Animal actions are almost universally constrained by the bilateral body-plan. For example, the direction of travel tends to be constrained by the orientation of the animal''s anteroposterior axis. Hence, an animal''s behaviour can reliably guide the identification of its front and back, and its orientation can reliably guide action prediction. We examine the hypothesis that the evolutionarily ancient relation between anteroposterior body-structure and behaviour guides our cognitive processing of agents and their actions. In a series of studies, we demonstrate that, after limited exposure, human infants as young as six months of age spontaneously encode a novel agent as having a certain axial direction with respect to its actions and rely on it when anticipating the agent''s further behaviour. We found that such encoding is restricted to objects exhibiting cues of agency and does not depend on generalization from features of familiar animals. Our research offers a new tool for investigating the perception of animate agency and supports the proposal that the underlying cognitive mechanisms have been shaped by basic biological adaptations in humans.     

面孔社会信息对注视提示效应的调制及其神经机制

眼睛注视是一种独特的非言语社会线索,能够诱发对生存和进化至关重要的注意效应。近年来,研究者采用中央线索提示范式及其变式,关注了面孔社会信息尤其是表情对这一注意效应的调节。面孔表情的调节作用与具体的表情类型有关,同时会受到任务因素和个体因素的影响。这一调节作用会随个体发展而逐渐成熟,与负责对面孔表情和注视方向各自及整合加工的机制相关,涉及到杏仁核和颞上沟脑区。除了面孔表情,其他面孔社会信息(如熟悉性和可信任度、优势度和社会地位、群体属性)也可以调节注视提示效应。这一调节可能涉及额叶视区、额顶注意网络。对面孔表情及其他社会信息调制注视提示效应的行为学证据及其神经机制进行系统综述,能够深化当前对面孔加工和注视提示效应间关系的理解,为社会认知障碍的临床诊断和干预提供参考。     

Neural mirroring mechanisms and imitation in human infants

Studying human infants will increase our understanding of the nature, origins and function of neural mirroring mechanisms. Human infants are prolific imitators. Infant imitation indicates observation–execution linkages in the brain prior to language and protracted learning. Investigations of neural aspects of these linkages in human infants have focused on the sensorimotor mu rhythm in the electroencephalogram, which occurs in the alpha frequency range over central electrode sites. Recent results show that the infant mu rhythm is desynchronized during action execution as well as action observation. Current work is elucidating properties of the infant mu rhythm and how it may relate to prelinguistic action processing and social understanding. Here, we consider this neuroscience research in relation to developmental psychological theory, particularly the ‘Like-Me’ framework, which holds that one of the chief cognitive tasks of the human infant is to map the similarity between self and other. We elucidate the value of integrating neuroscience findings with behavioural studies of infant imitation, and the reciprocal benefit of examining mirroring mechanisms from an ontogenetic perspective.     

新生隐球菌细胞通讯研究进展

细胞通讯系统调控多细胞生物的细胞增殖与分化等多种基础生物学过程,也是调控单细胞生物群体或社会性行为的重要策略。新生隐球菌是一种重要的环境来源病原真菌,主要感染免疫缺陷人群,具有很高的致死率。作为环境致病真菌,新生隐球菌进化出丰富的环境适应性策略。新生隐球菌细胞呈现出高度的异质性和社会性,不同形态的细胞承载着不同生物学功能和病原学特征。越来越多的研究表明,通过细胞通讯系统调控其群体或社会性行为,既是新生隐球菌适应多变的外界环境和宿主环境的关键策略,也与其致病能力密切相关。本文介绍新生隐球菌中细胞通讯系统的研究进展及其在有性生殖、细胞形态转换、适应环境及宿主压力等社会性行为中的调控作用。     

Group size,communication, and familiarity effects in foraging human teams

Exploitation of food resources that are dispersed in time and space has been crucial to the evolutionary success of humans. Recent experimental work has shown that an absence of communication impairs decision‐making in a foraging task. Here, we found that individuals in larger teams were more likely to reach group consensus and were more accurate and efficient foragers. Individuals in larger teams were also more likely to gesture to one another, while levels of verbal exchange were not significantly different in small and large groups. At last, teams in which individuals reported that they knew one another and rated team members as helpful and information‐seeking were more accurate in their foraging. Overall, our findings offer experimental evidence that larger, communicating, familiar teams are quicker and more accurate foragers. We therefore suggest that complex communication within socially bonded relationships may have been important to the ecological success of the human lineage.     

Developmental patterns of chimpanzee cerebral tissues provide important clues for understanding the remarkable enlargement of the human brain

Developmental prolongation is thought to contribute to the remarkable brain enlargement observed in modern humans (Homo sapiens). However, the developmental trajectories of cerebral tissues have not been explored in chimpanzees (Pan troglodytes), even though they are our closest living relatives. To address this lack of information, the development of cerebral tissues was tracked in growing chimpanzees during infancy and the juvenile stage, using three-dimensional magnetic resonance imaging and compared with that of humans and rhesus macaques (Macaca mulatta). Overall, cerebral development in chimpanzees demonstrated less maturity and a more protracted course during prepuberty, as observed in humans but not in macaques. However, the rapid increase in cerebral total volume and proportional dynamic change in the cerebral tissue in humans during early infancy, when white matter volume increases dramatically, did not occur in chimpanzees. A dynamic reorganization of cerebral tissues of the brain during early infancy, driven mainly by enhancement of neuronal connectivity, is likely to have emerged in the human lineage after the split between humans and chimpanzees and to have promoted the increase in brain volume in humans. Our findings may lead to powerful insights into the ontogenetic mechanism underlying human brain enlargement.     

Role of social cognition in post‐traumatic stress disorder: A review and meta‐analysis

Social functioning is a key component of recovery after a potentially traumatic experience, and the buffering role of the social support in trauma resilience and recovery has been very well documented. Factors contributing to resilience and recovery are notable because although most people will experience a traumatic event during their lifetimes, only 6% to 10% are diagnosed with post‐traumatic stress disorder (PTSD). The relationship between an individual and their social environment is determined both by the quality of the social environment itself, and by the individual's perception and understanding of information conveyed by the other people around them. However, little research has considered the contribution of these internal social cognitive processes to PTSD risk or resilience. The current review draws on the existing literature on social cognitive functioning in trauma exposure and PTSD, identifying key questions and themes for future research. We utilized a meta‐analytic approach to assess the evidence for alterations in social cognition in PTSD, finding a consistent large deficit in social cognitive performance in PTSD groups relative to trauma‐exposed and healthy controls. We then reviewed the literature on the interaction of genes and the social environment, supporting the hypothesis that social cognitive deficits are a preexisting risk factor for PTSD. Finally, we reviewed relevant neuroimaging findings, which suggest that alterations in social cognition affect the perception of threat cues in PTSD. Overall, research on social cognition and PTSD is still emerging, but existing findings suggest this is an important and understudied area for the understanding of PTSD.     

Social orienting in gaze leading: a mechanism for shared attention

Here, we report a novel social orienting response that occurs after viewing averted gaze. We show, in three experiments, that when a person looks from one location to an object, attention then shifts towards the face of an individual who has subsequently followed the person''s gaze to that same object. That is, contrary to ‘gaze following’, attention instead orients in the opposite direction to observed gaze and towards the gazing face. The magnitude of attentional orienting towards a face that ‘follows’ the participant''s gaze is also associated with self-reported autism-like traits. We propose that this gaze leading phenomenon implies the existence of a mechanism in the human social cognitive system for detecting when one''s gaze has been followed, in order to establish ‘shared attention’ and maintain the ongoing interaction.     

Se-mediated domain-domain communication in Band 3 of human erythrocytes

Na₂SeO₃ could affect the anion flux of Band 3 of inside-out erythrocyte membrane vesicles (IOVs). Such effect was believed to be based on the interaction of SH groups of Band 3 with Na₂SeO₃. This effect could be eliminated when the cytoplasmic domain of Band 3 was proteolytically removed by trypsin. This suggested that SH groups in the cytoplasmic domain were involved in such interaction. Measurement of the pH dependence of intrinsic fluorescence intensity provided evidence that conformational changes of Band 3 occurred as a consequence of interaction with selenite. KI quenching of intrinsic fluorescence of Band 3 could also show that there was a conformational change in the cytoplasmic domain of Band 3 after reaction with Na₂SeO₃. Such conformational change in turn could be transmitted to the membrane domain of Band 3 monitored by quenching of intrinsic fluorescence of Band 3 using hypocrellin B (HB) (a photosensitive pigment obtained from a parasitic fungus growing in Yunnan, China). It is suggested that the cytoplasmic domain of Band 3 is not necessary for its anion flux, but is essential for the regulation (e.g., by Se) of its active site located at the membrane domain, and hence, it may provide evidence of communication between the cytoplasmic domain and the membrane domain of Band 3.     

An exploration of the relationship between recruitment communication and foraging in stingless bees

Social information is widely used in the animal kingdom and can be highly adaptive. In social insects, foragers can use social information to find food, avoid danger, or choose a new nest site. Copying others allows individuals to obtain information without having to sample the environment. When foragers communicate information they will often only advertise high-quality food sources, thereby filtering out less adaptive information. Stingless bees, a large pantropical group of highly eusocial bees, face intense inter- and intra-specific competition for limited resources, yet display disparate foraging strategies. Within the same environment there are species that communicate the location of food resources to nest-mates and species that do not. Our current understanding of why some species communicate foraging sites while others do not is limited. Studying freely foraging colonies of several co-existing stingless bee species in Brazil, we investigated if recruitment to specific food locations is linked to 1) the sugar content of forage, 2) the duration of foraging trips, and 3) the variation in activity of a colony from 1 day to another and the variation in activity in a species over a day. We found that, contrary to our expectations, species with recruitment communication did not return with higher quality forage than species that do not recruit nestmates. Furthermore, foragers from recruiting species did not have shorter foraging trip durations than those from weakly recruiting species. Given the intense inter- and intraspecific competition for resources in these environments, it may be that recruiting species favor food resources that can be monopolized by the colony rather than food sources that offer high-quality rewards.     

Cortical networks for face perception in two-month-old infants

Newborns have an innate system for preferentially looking at an upright human face. This face preference behaviour disappears at approximately one month of age and reappears a few months later. However, the neural mechanisms underlying this U-shaped behavioural change remain unclear. Here, we isolate the functional development of the cortical visual pathway for face processing using S-cone-isolating stimulation, which blinds the subcortical visual pathway. Using luminance stimuli, which are conveyed by both the subcortical and cortical visual pathways, the preference for upright faces was not observed in two-month-old infants, but it was observed in four- and six-month-old infants, confirming the recovery phase of the U-shaped development. By contrast, using S-cone stimuli, two-month-old infants already showed a preference for upright faces, as did four- and six-month-old infants, demonstrating that the cortical visual pathway for face processing is already functioning at the bottom of the U-shape at two months of age. The present results suggest that the transient functional deterioration stems from a conflict between the subcortical and cortical functional pathways, and that the recovery thereafter involves establishing a level of coordination between the two pathways.     

Predictive motor activation during action observation in human infants

Certain regions of the human brain are activated both during action execution and action observation. This so-called ‘mirror neuron system’ has been proposed to enable an observer to understand an action through a process of internal motor simulation. Although there has been much speculation about the existence of such a system from early in life, to date there is little direct evidence that young infants recruit brain areas involved in action production during action observation. To address this question, we identified the individual frequency range in which sensorimotor alpha-band activity was attenuated in nine-month-old infants'' electroencephalographs (EEGs) during elicited reaching for objects, and measured whether activity in this frequency range was also modulated by observing others'' actions. We found that observing a grasping action resulted in motor activation in the infant brain, but that this activity began prior to observation of the action, once it could be anticipated. These results demonstrate not only that infants, like adults, display overlapping neural activity during execution and observation of actions, but that this activation, rather than being directly induced by the visual input, is driven by infants'' understanding of a forthcoming action. These results provide support for theories implicating the motor system in action prediction.