Fear, a negative emotion triggered by dangerous stimuli, can lead to psychiatric disorders such as phobias, anxiety disorders, and depression. Investigating the neural circuitry underlying congenital fear can offer insights into the pathophysiological mechanisms of related psychiatric conditions. Research on innate fear primarily centers on the response mechanisms to various sensory signals, including olfactory, visual and auditory stimuli. Different types of fear signal inputs are regulated by distinct neural circuits. The neural circuits of the main and accessory olfactory systems receive and process olfactory stimuli, mediating defensive responses like freezing. Escape behaviors elicited by visual stimuli are primarily regulated through the superior colliculus and hypothalamic projection circuits. Auditory stimuli-induced responses, including escape, are mainly mediated through auditory cortex projection circuits. In this article, we review the research progress on neural circuits of innate fear defensive behaviors in animals. We further discuss the different sensory systems, especially the projection circuits of olfactory, visual and auditory systems, to provide references for the mechanistic study of related mental disorders.
Animals ; Humans ; Fear/physiology* ; Nerve Net

Neural oscillatory phenomenon generally exists in the nervous system through a dynamic form. It plays a very important role in the brain, especially in the higher cognitive activities, such as information processing, transfer and integration, consolidating memory and so on. Furthermore, the specific activity pattern of neural oscillations is often associated with cognitive functions and their alterations. Accordingly, how to quantitatively analyze the pattern of neural oscillations becomes one of the fundamental issues in the computational neuroscience. In this review, we addressed a variety of analytic algorithms, which are commonly employed in our recent studies to investigate the issues of neurobiology and cognitive science. In addition, we tried to classify these analytic algorithms by distinguishing their different metrics, synchronization and coupling modes. Finally, multidimensional analytic algorithms for potential application have also been discussed.
Brain ; physiology ; Cognition ; Humans ; Memory ; Nerve Net ; physiology

Animals ; Behavior, Animal ; physiology ; Drosophila melanogaster ; physiology ; Female ; Instinct ; Male ; Nerve Net ; physiology ; Neurons ; physiology

In contrast to the spinal control of erection, relatively little is known about the brain control. In the present review, we have outlined the role of brain structures involved in penile erection and provided a synopsis on the brain circuit of erection. Findings from both animal and human studies are discussed. Evidence suggests that the most important structures are the frontal lobe, cingulate gyrus, amygdala, thalamus and hypothalamus. Within the brain circuit of erection, the thalamus serves as a gate-controller in which all relevant information is evaluated and further processed to higher and lower centres.
Brain ; physiology ; Humans ; Male ; Models, Neurological ; Nerve Net ; Penile Erection ; Thalamus ; physiology

The recent development of tools to decipher the intricacies of neural networks has improved our understanding of brain function. Optogenetics allows one to assess the direct outcome of activating a genetically-distinct population of neurons. Neurons are tagged with light-sensitive channels followed by photo-activation with an appropriate wavelength of light to functionally activate or silence them, resulting in quantifiable changes in the periphery. Capturing and manipulating activated neuron ensembles, is a recently-designed technique to permanently label activated neurons responsible for a physiological function and manipulate them. On the other hand, neurons can be transfected with genetically-encoded Ca indicators to capture the interplay between them that modulates autonomic end-points or somatic behavior. These techniques work with millisecond temporal precision. In addition, neurons can be manipulated chronically to simulate physiological aberrations by transfecting designer G-protein-coupled receptors exclusively activated by designer drugs. In this review, we elaborate on the fundamental concepts and applications of these techniques in research.
Animals ; Autonomic Pathways ; physiology ; Calcium Signaling ; physiology ; Humans ; Nerve Net ; physiology ; Neurons ; physiology ; Optogenetics ; methods ; Receptors, G-Protein-Coupled ; physiology

BACKGROUNDPrevious studies have demonstrated that acupuncture could modulate various brain systems in the resting brain networks. Graph theoretical analysis offers a novel way to investigate the functional organization of the large-scale cortical networks modulated by acupuncture at whole brain level. In this study, we used wavelets correlation analysis to estimate the pairwise correlations between 90 cortical and subcortical human brain regions in normal human volunteers scanned during the post-stimulus resting state.

METHODSThirty-two college students, all right-handed and acupuncture naïve, participated in this study. Every participant received only one acupoint stimulation, resulting in 16 subjects in one group. Both structural functional magnetic resonance imaging (fMRI) data (3D sequence with a voxel size of 1 mm(3) for anatomical localization) and functional fMRI data (TR = 1500 ms, TE = 30 ms, flip angle = 90°) were collected for each subject. After thresholding the resulting scale-specific wavelet correlation matrices to generate undirected binary graphs, we compared graph metrics of brain organization following verum manual acupuncture (ACU) and sham acupuncture (SHAM) groups.

RESULTSThe topological parameters of the large-scale brain networks in ACU group were different from those of the SHAM group at multiple scales. There existed distinct modularity functional brain networks during the post-stimulus resting state following ACU and SHAM at multiple scales.

CONCLUSIONSThe distinct modulation patterns of the resting brain attributed to the specific effects evoked by acupuncture. In addition, we also identified that there existed frequency-specific modulation in the post-stimulus resting brain following ACU and SHAM. The modulation may be related to the effects of verum acupuncture on modulating special disorder treatment. This preliminary finding may provide a new clue to understand the relatively function-oriented specificity of acupuncture effects.

Acupuncture Points ; Acupuncture Therapy ; Adult ; Analgesia ; Brain ; physiology ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Nerve Net

In 1905, Henry Head first suggested that transmission of pain-related protopathic information can be negatively modulated by inputs from afferents sensing innocuous touch and temperature. In 1965, Melzak and Wall proposed a more concrete gate control theory of pain that highlights the interaction between unmyelinated C fibers and myelinated A fibers in pain transmission. Here we review the current understanding of the spinal microcircuits transmitting and gating mechanical pain or itch. We also discuss how disruption of the gate control could cause pain or itch evoked by innocuous mechanical stimuli, a hallmark symptom for many chronic pain or itch patients.
Animals ; Humans ; Nerve Net ; pathology ; physiopathology ; Pain ; pathology ; Pruritus ; pathology ; Spinal Cord ; pathology ; Synaptic Transmission ; physiology

We review our work on computational modeling of the mammalian visual cortex. In particular, we explain the network mechanism of how simple and complex cells arise in a large scale neuronal network model of primary visual cortex. The simple cells are so-called because they respond approximately linearly to visual stimulus, whereas the complex cells exhibit nonlinear response to visual stimulation. Our model reproduces qualitatively the experimentally observed distributions of simple and complex cells.
Animals ; Computer Simulation ; Humans ; Models, Neurological ; Nerve Net ; physiology ; Neurons ; physiology ; Photic Stimulation ; Visual Cortex ; cytology ; physiology

Brain functional network changes over time along with the process of brain development, disease, and aging. However, most of the available measurements for evaluation of the difference (or similarity) between the individual brain functional networks are for charactering static networks, which do not work with the dynamic characteristics of the brain networks that typically involve a long-span and large-scale evolution over the time. The current study proposes an index for measuring the similarity of dynamic brain networks, named as dynamic network similarity (DNS). It measures the similarity by combining the "evolutional" and "structural" properties of the dynamic network. Four sets of simulated dynamic networks with different evolutional and structural properties (varying amplitude of changes, trend of changes, distribution of connectivity strength, range of connectivity strength) were generated to validate the performance of DNS. In addition, real world imaging datasets, acquired from 13 stroke patients who were treated by transcranial direct current stimulation (tDCS), were used to further validate the proposed method and compared with the traditional similarity measurements that were developed for static network similarity. The results showed that DNS was significantly correlated with the varying amplitude of changes, trend of changes, distribution of connectivity strength and range of connectivity strength of the dynamic networks. DNS was able to appropriately measure the significant similarity of the dynamics of network changes over the time for the patients before and after the tDCS treatments. However, the traditional methods failed, which showed significantly differences between the data before and after the tDCS treatments. The experiment results demonstrate that DNS may robustly measure the similarity of evolutional and structural properties of dynamic networks. The new method appears to be superior to the traditional methods in that the new one is capable of assessing the temporal similarity of dynamic functional imaging data.
Aging/physiology* ; Brain/physiology* ; Brain Mapping ; Humans ; Magnetic Resonance Imaging/methods* ; Nerve Net/physiology* ; Transcranial Direct Current Stimulation/methods*

Studying the functional network during the interaction between emotion and cognition is an important way to reveal the underlying neural connections in the brain and nowadays, it has become a hot topic in cognitive neuroscience. Granger causality (GC), based on multivariate autoregressive (MVAR) model, and being able to be used to analyse causal characteristic of brain regions has been widely used in electroencephalography (EEG) in event-related paradigms research. In this study, we recorded the EEGs from 13 normal subjects (6 males and 7 females) during emotional face search task. We utilized Granger causality to establish a causal model of different brain areas under different rhythms at specific stages of cognition, and then convinced the brain dynamic network topological properties in the process of emotion and cognition. Therefore, we concluded that in the alpha band, (1) negative emotion face induced larger causal effects than positive ones; (2) 100-200ms emotional signal was the most prominent ones while 300-400ms and 700-800ms would take the second place; (3) The rear brain region modulated the front in the process of causal modulation; (4) The frontal and pillow area involved in the brain causal modulation as a key brain area; and (5) Negative partiality existed in the information processing, especially during 0-100ms after the negative expression stimulation.
Alpha Rhythm ; physiology ; Brain ; physiology ; Cell Communication ; physiology ; Cognition ; physiology ; Electroencephalography ; Emotions ; physiology ; Evoked Potentials ; physiology ; Female ; Humans ; Male ; Models, Neurological ; Multivariate Analysis ; Nerve Net ; physiology ; Neurons ; physiology