Abstract:Status quo and the leading edge of brain and cognitive science

Abstract:Understanding the mechanisms of consciousness is a major and challenging question in neuroscience. Studies of the neural correlates of visual awareness have benefited from using bistable phenomena such as binocular rivalry, in which conscious perception fluctuates with constant visual inputs. Non-invasive neuroimaging techniques, especially functional MRI, made it possible to directly investigate the neural correlate of consciousness in the human brain. The focus of this review is on studies related to the unconscious visual information processing in the parallel visual pathways as well as in the subcortical visual structures. Future research to explore the neural mechanisms of consciousness will need to be highly interdisciplinary and integrative, over a broad range of spatiotemporal scales and across different species.

Abstract:Neural oscillations are intrinsically rhythmic. With rhythmic stimulation, the endogenous neural oscillations become phase-locked to the external rhythm, resulting in oscillatory and stimulus-dependent changes in neural excitability. This phenomenon, known as neural entrainment, serves as a non-invasive method to affect brain activity that mediates rhythmic information processing, perception, attention, and other related cognitive functions. Future studies on neural entrainment will delineate the functional role of neural oscillations in perception and cognition, and may contribute to the diagnosis and intervention of cognitive disorders.

Abstract:The looming priority refers to organisms’ prior processing of or greater sensitivity to looming signals . The looming priority has been commonly found in visual, auditory and cross modalities and different kinds of subjects including human and animals. Humanneuroimaging studies suggest that neural substrate associated with the priority involves a massive distributed neural network coordinating and communicating to each other, including the superior temporal sulcus, right temporoparietal junction and some motor areas. The neurons and neural pathways selectively sensitive to looming signals have been found in many kinds of animals. The looming priority is explained from different perspectives, including threatening hypothesis, attentional capture hypothesis and automatic processing hypothesis. Future studies may focus on the role of social and emotional features of looming stimuli and the integration mechanism of multisensory looming stimuli.

Abstract:Fight-or-flight response is a series of behavioral and physiological reactions triggered by life-threatening stress. These reactions enable individuals to escape from or defend against environmental threats, thus increasing the survival rate in dangerous situations. Stong or repeated fight-or-flight response sometimes causes a type of mental disorder, namely post-traumatic stress disorder (PTSD). Frequent natural disasters and traffic accidents have endangered Chinese people with PTSD. PTSD treatment calls for understanding the fundamental neural circuit mechanisms underlying fight-or-flight response.In this review, we will summarize recent progress in this field, and emphasize the significance of this research field in the China.

Abstract:To fully understand the mystery of the brain is the biggest challenge facing the modern science. A deeper knowledge of how a brain works will have profound implications, both for appreciating our own minds, ranging from intelligence to emotion, and for treatments of brain diseases that have brought much sufferings to individuals and society. As a model organism for modern neuroscience, the common fruit fly, Drosophila, is emerging as one of the primary choice for studying the genetic basis and neural circuit of behavior. This review will focus on higher brain functions, including learning and memory, motivation, emotional and social behaviors in Drosophila. We will cover the significance, background, current progress, and prospect of the related topics. We hope this review would help the readers to catch a glimpse of the dynamic range of Drosophila neurogenetic research and the leading edge of the brain science.

Abstract:Learning and memory is a delicate process of acquiring, storing and reconsolidating the knowledge with a behavioral output, which is indispensable for animals to adapt to their living environment. Defects in learning and memory contribute to some psychiatric disorders such as schizophrenia, depression and Alzheimer’s disease, and are recently reported to be inheritable from the parental generation to their offspring. However, it is not clear currently what the mechanism is underlying the learning and memory inheritance due to the lack of animal models. In this perspective type of mini-review, we first briefly summarize the current understanding of the molecular basis, neural circuit and transgenerational inheritance of learning and memory. We then focus on discussing the possibility of using Drosophila as an animal model to study the transgenerational inheritance of learning and memory and propose potential strategies to achieve the goal.

Abstract:Among vast stars in the universe, the earth is distinctive for the existence of intelligent life on its surface. We wonder the origin of life, and meanwhile, we are also intrigued by the emergence of intelligence. What is the essence of intelligence? How does it emerge? During the Cambrian Explosion, a huge amount of species burst, moreover, the nervous system emerged for information perception, coding and processing. Contemporaneously, insects emerged and have existed for 400 million years in the complicated and fickle environment. In this article, we discuss the basic properties of intelligence on the basis of research findings in modern Drosophila cognitive neuroscience. We thereby propose that Drosophila brain is an important milestone in the emergence of intelligence, thus serving as the first station in our journey of uncovering the intelligence essence and entering the kingdom of intelligence.

Abstract:In the past decade, optogenetics is one of the most popular neuromodulation techniques in neuroscience. This review first briefly introduces the basic principle of optogenetics and summarizes its advantages in comparing with those traditional methods, and then lists some potential applications of this novel technique. In order to promote the conversion of optogenetic treatment in clinics, it is necessary to integrateoptogenetics with nonhuman primate study. This review then systematically looksback the progress of optogenetic studies in the nonhuman primates, and particularly highlights the work done by Dai et al.. In addition, this review also points out some challenges towards the development of optogenetics in the future. In the end, to advance the optogenetic-related studies, especially in the nonhuman primates, this review proposes some suggestions to the planning “Chinese Brain Initiative”.

Abstract:Luminance is the most fundamental visual information. In comparison with other visual attributes, we know less about the neural mechanism responsible for coding luminance due to that visual neurons weakly respond to uniform luminance and many of them do not respond. Responses of a portion of neurons to luminance in the primary visual cortex are slower than those to contrast, which is thought to subserve the perceptual brightness induced by contrast at the borders of uniform luminance. However, our recent studies show that luminance responses of many neurons in the primary visual cortex are faster than contrast responses, and these neurons are more sensitive to lower spatial frequencies, higher temporal frequencies, and faster motion speed. The results indicate that the subcortical inputs of low spatial frequency and high motion speed channels contribute the generation of luminance responses of these neurons. It is known that responses to low spatial frequencies precede those to high spatial frequencies, which is thought to underlie the coarse-to-fine process of information processing in the early visual pathway. The early luminance response we reveal is the response to the extremely low spatial frequency, which is consistent with the temporal course of responses to low-to-high spatial frequencies. The rapid luminance response is the initial step of the coarse-to-fine process and the neural basis for processing the earliest coarse visual information. Moreover, the primary visual cortex contains a group of neurons that prefer luminance decrements and high motion speeds. The activities of these neurons may aid subjects to detect dark objects that are moving at high speeds under dim environment and benefit behaviors of subjects in the visual context.

Abstract:The brain acquires sensory signals and programs neural codes to manager cognitions and behaviors, to which the signal storage and encoding done by the neurons in brain circuits are essential. The elucidation of principles how the neurons encode and memorize input signals is basic to develop brain-simulated computers. Here, we briefly review the principles of neuron encoding and memory cell working, such as the conversion of analogue to digital signals, the compatible output of digital signals as well as the memory of input signals. The conversion of analogue-to-digital signal is influenced by the transmitter release pattern and probability from presynaptic terminals, the receptor responsiveness and density in postsynaptic spines as well as the number and ratio of excitatory versus inhibitory synapses. The integrated signals instigate the soma to encode digital spikes. When these spikes are propagated on axonal branches, their propagation efficiency is compatible with spiking ability in postsynaptic partner neurons. In terms of the storage and retrieval of newly acquired signals, the characteristics of associative memory cells include the followings. They are recruited to encode multiple signals being associated. They receive multiple synaptic inputs from the locations of signals’ origins. Their axons project toward the brain areas being associatively activated, as well as other brain regions for memory presentation. Their recruitments are downregulated by changing gene and protein expressions with microRNA manipulations or others. The upregulation or downregulation of these neurons, their synaptic inputs and axon projections changes memory capacity. Their axons project to the contralateral cortices and make the synapse innervations that send the acquired signals for unilateral learning toward bilateral memory.

Abstract:The mitochondria are the energy-generating organelles in the cytoplasm of the cell. They also serve as signaling organelles that coordinate complex cellular functions. Mitochondria are highly dynamic and undergo fusion and fission processes continuously, which is crucial for the maintenance of mitochondrial homeostasis and the balance of mitochondrial turnover. Although most of the evolutionarily conserved core components of the mitochondrial fusion and fission machineries have been identified in the past decade, the mechanistic insights into their molecular functions remain to be investigated. Mitochondrial fusion and fission (collectively termed mitochondrial dynamics) takes part in cellular quality control system and play a key role in the development of the cell, tissue and organism. Dysfunctions of mitochondrial dynamics are implicated in various inherited and age-related neurodegenerative diseases. Thus, the research in the relationship between mitochondrial biology and diseases will remain an exciting field in the coming years.

Abstract:Hippo signaling pathway regulates cell proliferation，differentiation and apoptosis and plays a critical role in the tissue development and homeostasis. We identified Hippo/MST1-YAP signaling is involved BMP2-mediated self-renewal of neuron progenitor cells. We also found MST1 induced neuronal cell death in oxidase stress and c-Abl，a non-receptor tyrosine kinase，function as an upstream regulator of MST1 during the process. Recently，we found MST1 play important role in ischemic stroke induced neuro-inflammation. In this review，we will briefly summarize the significant progress of Hippo signaling in the central nervous system diseases as well as neuronal development.

Abstract:Changes of cerebral cortex size and brain volume have experienced evolutionary expansion across mammals, which is the cellular base of neuronal network complexity. The existence of cortex folding, allowing huge area of cortex to fit into a relatively small cranial space, is one of important evolutionary features in primate. The adult human CNS contains approximately 86.1 billion neurons and equal number of glial cells. Among which, human cerebral cortex consists of roughly 16.34 billion neurons. Based on algorithm analysis, approximately 3.86 million projection (excitatory/pyramidal) neurons are generated per hour during prenatal cortical neurogenesis in human. Such an incredible fast speed of neurogenesis suggests that human neocortex development requires strictly organized molecular regulations and cellular processes. Here we discuss the molecular and cellular characteristics of mammalian cerebral cortex expansion and the related disease.

Abstract:Implied action is defined as extraction of action information from a stationary photo. By using central cuing versions of the non-predictive and counter-predictive covert-orienting paradigms, the present study firstly investigated the attention shiftsinduced by the implied action and non-action cues. Then we further tested whether these cues produce reflexive or voluntary shifts of attention. In experiment 1 and 2, by using the non-predictive paradigm, we found that the throwing cue (implied action) directs spatial attention, irrespective of an abrupt onset target attracting attention. In experiment 3, by adopting a counter-predictive task, the results showed that implied action cues trigger attention shifts voluntarily. Moreover, the results in all three experiments revealed that trunk orientation alone (standing cue) is not sufficient to shiftone’s spatial attention. The present study extends the view of “direction of attention detector”, and further suggests that implied action as global body posture cue, the orienting mechanism might be different from that induced by local biological cues.

Abstract:When faces are categorized by their race, participants often respond faster and more accurately to other-race faces than to own-race faces, and this is known as other-race categorization advantage. It has been evident for enhanced recognition of other-race faces with positive or negative emotions, but it remains unclear whether categorization of other-race faces receive similar impact from emotions. This study was to examine how emotions modualtes the categorization of other-race faces. Experiment 1 asked young participants to categorize faces with neutral, positive or negative expressions by their race, and found both positive and negative expressions slowed down the categorization of other-race faces and weakened the other-race categorization advantage. Experiment 2 recruited elders to judge the race of faces, and found they categorized other-race faces more slower, and the other-race categorization advantage was weakened by negative expressions to a greater extent for elders than for youngers. These results provided further evidence for the hypothesis of the competition between individual identity process and categorization process, which was a common implication of several theories on other-race categorization advantage.

Abstract:In the early visual pathway, the lateral geniculate nucleus (LGN) is the major relay station from where visual information is transmitted to the cerebral cortex. How LGN neurons code luminance remains unclear. We addressed the issue by presenting the luminance stimuli that were continuously changing at 50 Hz to neurons of cat LGN. The rapid changes in luminance enhanced responses of LGN neurons to uniform stimuli. Responses of a neuron to the luminance stimuli were sorted using the reverse correlation algorithm and luminance response function (LRF) was extracted from the responses. Most neurons (81%) had either increase or decrease LRFs, and the remaining neurons (19%) had V-shape LRFs. The relationships between the response magnitudes to luminance increments and decrements of uniform stimuli and those to ON and OFF stimuli presented inside receptive field (RF) revealed that the increase, decrease, and V-shape LRFs of most neurons (83%) were determined by the relative strength of ON-OFF responses of their RFs, and the LRFs of the other neurons (17%) were related to the excitation-inhibition interactions between RF ON-center (or surround) and OFF-surround (or center) of RF structure. The results unveiled the neural mechanisms underlying the responses of LGN neurons to uniform luminance.

Abstract:There were lots of studies reporting the toxic effects of formaldehyde on various organs of human and animals, but the differences of effects among various concentrations of formaldehyde were rarely reported. In this paper, we used Drosophila melanogaster as model organism, added different proportions of formaldehyde into the fly food, and observed the effects on life span and stress resistance. The results showed that the life span of female flies depended on the formaldehyde concentrations, 0.037% formaldehyde could significantly extend the life span of female flies, whereas the higher concentrations of formaldehyde (≥0.185%) could significantly reduce the life span of male and female flies. What's more, 0.037% formaldehyde significantly increased the starvation resistance and heat shock resistance, but reduced the oxidative resistance in both male and female flies. These results provided a new way to study the molecular mechanisms of longevity and stress resistance in Drosophila.

Abstract:Chronic dehydration is regarded as a common symptom of patients with age-related cognitive impairment, particularly those with Alzheimer disease. Chronic dehydration causes not only serum hyperosmotic-pressure increase, but also metabolic dysfunction of central nerve system and cognitive impairment. Here, we show the establishment of an animal model for chronic dehydration with C57 BL/6 mouse that was administrated with 4% NaCl instead of water intake for 3 months. For NaCl-fed group, serum osmotic pressure and Na+ concentration were significantly increased and their body weight was decreased, indicating the chronic dehydrated symptoms. The chronic dehydrated mice (fed with 4% NaCl) with a marked low level of 5-hydroxltryptamine showed slower learning in“Shuttle box”behavior assay than those fed with water as controls. Brain formaldehyde was increased following an imbalance of the activities between semicarbazide sensitive amine oxidase (SSAO) and formaldehyde dehydrogenase 3 (ADH3). To demonstrate that dysmetabolism of formaldehyde induces a low level of 5-hydroxltryptamine (5-HT) and the slow learning, formaldehyde was intraperitoneally injected to the mouse for 7 days. The results showed that formaldehyde injection leads to an elevation of 5-HT and slow-learning in shuttle box, however, 4% NaCl injection does not result in any significant differences in 5-HT and behavior assay. These data suggest that chronic dehydration in mice results in dysregulation of brain formaldehyde, which decreases the level of 5-HT and slows learning in shuttle box.