Subjects: Biology >> Biophysics submitted time 2016-05-12
Abstract： What is a number? The number sense hypothesis suggests that numerosity is "a primary visual property" like color, contrast, or orientation. However, exactly what attribute of a stimulus is the primary visual property and determines numbers in the number sense? To verify the invariant nature of numerosity perception, we manipulated the numbers of items connected/enclosed in arbitrary and irregular forms while controlling for low-level features (e.g., orientation, color, and size). Subjects performed discrimination, estimation, and equality judgment tasks in a wide range of presentation durations and across small and large numbers. Results consistently show that connecting/enclosing items led to robust numerosity underestimation, with the extent of underestimation increasing monotonically with the number of connected/enclosed items. In contrast, grouping based on color similarity had no effect on numerosity judgment. We propose that numbers or the primitive units counted in numerosity perception are influenced by topological invariants, such as connectivity and the inside/outside relationship. Beyond the behavioral measures, neural tuning curves to numerosity in the intraparietal sulcus were obtained using functional MRI adaptation, and the tuning curves showed that numbers represented in the intraparietal sulcus were strongly influenced by topology.
Peer Review Status:
Awaiting Review
Subjects: Biology >> Biophysics >> Neurosciences submitted time 2016-05-12
Abstract： The brain constantly creates perceptual predictions about forthcoming stimuli to guide perception efficiently. Abundant studies have demonstrated that perceptual predictions modulate sensory activities depending on whether the actual inputs are consistent with one particular prediction. In real-life contexts, however, multiple and even conflicting predictions might concurrently exist to be tested, requiring a multiprediction coordination process. It remains largely unknown how multiple hypotheses are conveyed and harmonized to guide moment-by-moment perception. Based on recent findings revealing that multiple locations are sampled alternatively in various phase of attentional rhythms, we hypothesize that this oscillation-based temporal organization mechanism may also underlie the multiprediction coordination process. To address the issue, we used well established priming paradigms in combination with a time-resolved behavioral approach to investigate the fine temporal dynamics of the multiprediction harmonization course in human subjects. We first replicate classical priming effects in slowly developing trends of priming time courses. Second, after removing the typical priming patterns, we reveal a new theta-band (similar to 4 Hz) oscillatory component in the priming behavioral data regardless of whether the prime was masked. Third, we show that these theta-band priming oscillations triggered by congruent and incongruent primes are in an out-of-phase relationship. These findings suggest that perceptual predictions return to low-sensory areas not continuously but recurrently in a theta-band rhythm (every 200-300 ms) and that multiple predictions are dynamically coordinated in time by being conveyed in different phases of the theta-band oscillations to achieve dissociated but temporally organized neural representations.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-12
Wei, Pengfei
Liu, Nan
Liu, Xuemei
Tang, Yongqiang
Wu, Bifeng
Zhou, Zheng
Liu, Yaohan
Li, Juan
Zhang, Yi
Wang, Liping
Wei, Pengfei
Liu, Nan
Liu, Xuemei
Tang, Yongqiang
Wu, Bifeng
Zhou, Zheng
Liu, Yaohan
Li, Juan
Zhang, Yi
Wang, Liping
Abstract： The ability of animals to respond to life-threatening stimuli is essential for survival. Although vision provides one of the major sensory inputs for detecting threats across animal species, the circuitry underlying defensive responses to visual stimuli remains poorly defined. Here, we investigate the circuitry underlying innate defensive behaviours elicited by predator-like visual stimuli in mice. Our results demonstrate that neurons in the superior colliculus (SC) are essential for a variety of acute and persistent defensive responses to overhead looming stimuli. Optogenetic mapping revealed that SC projections to the lateral posterior nucleus (LP) of the thalamus, a non-canonical polymodal sensory relay, are sufficient to mimic visually evoked fear responses. In vivo electrophysiology experiments identified a di-synaptic circuit from SC through LP to the lateral amygdale (Amg), and lesions of the Amg blocked the full range of visually evoked defensive responses. Our results reveal a novel collicular-thalamic-Amg circuit important for innate defensive responses to visual threats.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-12
Qin, Dongdong
Rizak, Joshua
Chu, Xunxun
Li, Zhifei
Yang, Shangchuan
Feng, Xiaoli
Hu, Xintian
Qin, Dongdong
Rizak, Joshua
Chu, Xunxun
Li, Zhifei
Yang, Shangchuan
Feng, Xiaoli
Hu, Xintian
Qin, Dongdong
Chen, Lin
Lu, Longbao
Hu, Xintian
Yang, Lichuan
Yang, Lichuan
Abstract： Non-human primates offer unique opportunities to study the development of depression rooted in behavioral and physiological abnormalities. This study observed adult female rhesus macaques within social hierarchies and aimed to characterize the physiological and brain abnormalities accompanying depressive-like behavior. The behaviors of 31 female rhesus macaques from 14 different breeding groups were video recorded, and the footage was analyzed using the focal animal technique. There were 13 monkeys who never displayed huddling behavior (non-huddlers). The remaining 18 monkeys were divided into two groups according the mean time spent in the huddle posture. Four monkeys were designated as high huddlers, whereas the other 14 monkeys were low huddlers. An inverse relationship was discovered between social rank and depression. High huddlers spent more time engaging in physical contact and in close proximity to other monkeys, as well as less time spontaneously and reactively locomoting, than low huddlers and/or non-huddlers. Cortisol levels measured from the hair were elevated significantly in high huddlers compared with low huddlers and non-huddlers, and the measured cortisol levels were specifically higher in high huddlers than subordinate or dominant control monkeys. Regional cerebral blood flow data revealed significant and widespread decreases in high huddlers compared with non-huddlers.
Peer Review Status:Awaiting Review
Subjects: Biology >> Biophysics submitted time 2016-05-11
Qin, Dongdong
Rizak, Joshua
Feng, Xiaoli
Yang, Shangchuan
Fan, Xiaona
Hu, Xintian
Qin, Dongdong
Rizak, Joshua
Feng, Xiaoli
Yang, Shangchuan
Fan, Xiaona
Hu, Xintian
Lue, Longbao
Hu, Xintian
Rizak, Joshua
Qin, Dongdong
Chen, Lin
Yang, Lichuan
Yang, Lichuan
Abstract： Accumulating evidence has shown that a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) moderates the association between stress and depressive symptoms. However, the exact etiologies underlying this moderation are not well understood. Here it is reported that among adult female rhesus macaques, an orthologous polymorphism (rh5-HTTLPR) exerted an influence on cortisol responses to chronic stress. It was found that females with two copies of the short allele were associated with increased cortisol responses to chronic stress in comparison to their counterparts who have one or two copies of the long allele. In the absence of stress, no differences related to genotype were observed in these females. This genetic moderation was found without a genetic influence on exposure to stressful situations. Rather it was found to be a genetic modulation of cortisol responses to chronic stress. These findings indicate that the rh5-HTTLPR polymorphism is closely related to hypothalamus pituitary adrenal (HPA) axis reactivity, which may increase susceptibility to depression in females with low serotonin transporter efficiency and a history of stress. (C) 2014 Elsevier B.V. All rights reserved.
Peer Review Status:Awaiting Review
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