A spatial localization model of mobile robot based on entorhinal-hippocampal cognitive mechanism in rat brain / 生物医学工程学杂志

Physiological studies reveal that rats rely on multiple spatial cells for spatial navigation and memory. In this paper, we investigated the firing mechanism of spatial cells within the entorhinal-hippocampal structure of the rat brain and proposed a spatial localization model for mobile robot. Its characteristics were as follows: on the basis of the information transmission model from grid cells to place cells, the neural network model of place cells interaction was introduced to obtain the place cell plate with a single-peaked excitatory activity package. Then the solution to the robot's position was achieved by establishing a transformation relationship between the position of the excitatory activity package on the place cell plate and the robot's position in the physical environment. In this paper, simulation experiments and physical experiments were designed to verify the model. The experimental results showed that compared with RatSLAM and the model of grid cells to place cells, the positioning performance of the model in this paper was more accurate, and the cumulative error in the long-time path integration process of the robot was also smaller. The research results of this paper lay a foundation for the robot navigation method that mimics the cognitive mechanism of rat brain.

A grid field calculation model based on perceived speed and perceived angle / 生物医学工程学杂志

The method of directly using speed information and angle information to drive attractors model of grid cells to encode environment has poor anti-interference ability and is not bionic. In response to the problem, this paper proposes a grid field calculation model based on perceived speed and perceived angle. The model has the following characteristics. Firstly, visual stream is decoded to obtain visual speed, and speed cell is modeled and decoded to obtain body speed. Visual speed and body speed are integrated to obtain perceived speed information. Secondly, a one-dimensional circularly connected cell model with excitatory connection is used to simulate the firing mechanism of head direction cells, so that the robot obtains current perception angle information in a biomimetic manner. Finally, the two kinds of perceptual information of speed and angle are combined to realize the driving of grid cell attractors model. The proposed model was experimentally verified. The results showed that this model could realize periodic hexagonal firing field mode of grid cells and precise path integration function. The proposed algorithm may provide a foundation for the research on construction method of robot cognitive map based on hippocampal cognition mechanism.

Activation of the Brain to Postpone Dementia: A Concept Originating from Postmortem Human Brain Studies / 神经科学通报·英文版

Alzheimer's disease (AD) is characterized by decreased neuronal activity and atrophy, while hyperactivity of neurons seems to make them resistant to aging and neurodegeneration, a phenomenon which we have paraphrased as 'use it or lose it'. Our hypothesis proposes that (1) during their functioning, neurons are damaged; (2) accumulation of damage that is not repaired is the basis of aging; (3) the vulnerability to AD is determined by the genetic background and the balance between the amount of damage and the efficiency of repair, and (4) by stimulating the brain, repair mechanisms are stimulated and cognitive reserve is increased, resulting in a decreased rate of aging and risk for AD. Environmental stimulating factors such as bilingualism/multilingualism, education, occupation, musical experience, physical exercise, and leisure activities have been reported to reduce the risk of dementia and decrease the rate of cognitive decline, although methodological problems are present.

Study of dynamic characteristics of scale-free spiking neural networks based on synaptic plasticity / 生物医学工程学杂志

Biological neural networks have dual properties of small-world attributes and scale-free attributes. Most of the current researches on neural networks are based on small-world networks or scale-free networks with lower clustering coefficient, however, the real brain network is a scale-free network with small-world attributes. In this paper, a scale-free spiking neural network with high clustering coefficient and small-world attribute was constructed. The dynamic evolution process was analyzed from three aspects: synaptic regulation process, firing characteristics and complex network characteristics. The experimental results show that, as time goes by, the synaptic strength gradually decreases and tends to be stable. As a result, the connection strength of the network decreases and tends to be stable; the firing rate of neurons gradually decreases and tends to be stable, and the synchronization becomes worse; the local information transmission efficiency is stable, the global information transmission efficiency is reduced and tends to be stable, and the small-world attributes are relatively stable. The dynamic characteristics vary with time and interact with each other. The regulation of synapses is based on the firing time of neurons, and the regulation of synapses will affect the firing of neurons and complex characteristics of networks. In this paper, a scale-free spiking neural network was constructed, which has biological authenticity. It lays a foundation for the research of artificial neural network and its engineering application.

The neural mechanism of visual contour integration / 生理学报

The human visual system efficiently extracts local elements from cluttered backgrounds and integrates these elements into meaningful contour perception. This process is a critical step before object recognition, in which contours often play an important role in defining the shapes and borders of the to-be-recognized objects. However, the neural mechanism of the contour integration is still under debate. The investigation of the neural mechanism underlying contour integration could deepen our understanding of perceptual grouping in the human visual system and advance the development of the algorithms for image grouping and segmentation in computer vision. Here, we review two theoretical frameworks that were proposed over the past decades. The first framework is based on hardwired horizontal connection in primary visual cortex, while the second one emphasizes the role of recurrent connections within intra- and inter-areas. At the end of review, we also raise the unsolved issues that need to be addressed in future studies.

Cognitive and neural mechanisms underlying working memory / 生理学报

Working memory (WM) refers to the process of temporally maintaining and manipulating input information. WM is the global workspace of cognitive functions, however, with severely restricted capacity and precision. Previous cognitive and computational models discussed the methods of calculating capacity and precision of WM and the reason why they are so limited. It still remains debated which model is the best across all datasets, and whether there exists upper limits of items. Besides, sensory cortices and the frontal-parietal loop are suggested to represent WM memorandum. Yet recently, the sensory recruitment hypothesis that posits an important role of sensory cortices in WM is strongly argued. Meanwhile, whether the prefrontal cortex shows sustained activity or bursting γ oscillations is intensely debated as well. In the future, disentangling the contribution to WM of feedforward γ vs feedback α/β oscillations, and/or dopamine vs serotonin systems, is critical for understanding the neural mechanisms underlying WM. It will further do help to recognize the basis for the psychiatric (e.g. schizophrenia) or neurological (e.g. Alzheimer's disease) disorders, and potentially to develop effective training and intervening methods.

Modelos de la Memoria de Trabajo de Baddeley y Cowan: una revisión bibliográfica comparativa / Models of Working Memory: where do they meet?

La memoria de trabajo (MT) ha servido de predictor para fenómenos como el desempeño escolar en matemáticas, el nivel de comprensión lectora y el aprendizaje de estudiantes con desarrollo atípico. Esto le ha llevado a tomar un rol clave en los estudios cognitivos. Debido a la importancia que ha tomado la MT, se vuelve relevante explorar modelos que expliquen este constructo de manera de acercar estas propuestas a los investigadores que se estén familiarizando con esta temática. El presente artículo presenta y compara el modelo multicomponencial de Baddeley y Hitch (1974) y sus actualizaciones posteriores (Baddeley, 2000, 2012, 2017) con el modelo integrado de atención y memoria de Cowan (1988, 1995, 2005). Desde la revisión detallada de ambas propuestas se realiza una comparación utilizando como criterios el rol de la memoria en el modelo, la equivalencia entre los componentes del modelo y la manera en la cual se propone se manipula la información. Los hallazgos de esta revisión muestran que aun cuando existen equivalencias de algunos de los elementos de ambas propuestas, los distintos énfasis de ambos modelos resultan en interpretaciones distintas de los sustentos empíricos y del funcionamiento de la MT en relación con los roles de la memoria a largo plazo y la atención.

Working Memory (MT) has served as a predictor for phenomena such as school performance in mathematics, reading comprehension and learning of students with atypical development. This has given it a key role in cognitive studies. Due to the importance that WM has taken, it becomes relevant to explore models that explain this construct to bring these proposals closer to researchers who are becoming familiar with this topic. The present article presents and compares the multicomponent model of Baddeley and Hitch (1974) and its subsequent updates (Baddeley, 2000, 2012, 2017) with the integrated attention and memory model of Cowan (1988, 1995, 2005). From the detailed review of both proposals a comparison is made using as criteria the role of memory in the model, the equivalence between the components of both models and the way in which the information is stored and accessed. The findings of this review show that although there are equivalences among some of the elements of both proposals, the different emphases of both models result in different interpretations of the empirical underpinnings and the functioning of WM in relation to the roles of the long-term memory and attention.

Neuroprotective effect of the ethanol extract of Artemisia capillaris on transient forebrain ischemia in mice via nicotinic cholinergic receptor / 中国天然药物

Artemisia capillaris Thunberg is a medicinal plant used as a traditional medicine in many cultures. It is an effective remedy for liver problems including hepatitis. Recent pharmacological reports have indicated that Artemisia species can exert various neurological effects. Previously, we reported a memory-enhancing effect of Artemisia species. However, the mechanisms underlying the neuroprotective effect of A. capillaris (AC) are still unknown. In the present study, we investigated the effect of an ethanol extract of AC on ischemic brain injury in a mouse model of transient forebrain ischemia. The mice were treated with AC for seven days, beginning one day before induction of transient forebrain ischemia. Behavioral deficits were investigated using the Y-maze. Nissl and Fluoro-jade B staining were used to indicate the site of injury. To determine the underlying mechanisms for the drug, we measured acetylcholinesterase activity. AC (200 mg·kg) treatment reduced transient forebrain ischemia-induced neuronal cell death in the hippocampal CA1 region. The AC-treated group also showed significant amelioration in the spontaneous alternation of the Y-maze test performance, compared to that in the untreated transient forebrain ischemia group. Moreover, AC treatment showed a concentration-dependent inhibitory effect on acetylcholinesterase activity in vitro. Finally, the effect of AC on forebrain ischemia was blocked by mecamylamine, a nonselective nicotinic acetylcholine receptor antagonist. Our results suggested that in a model of forebrain ischemia, AC protected against neuronal death through the activation of nicotinic acetylcholine receptors.

Wandering Minds with Wandering Brain Networks / 神经科学通报·英文版

The default mode network (DMN) is associated with the occurrence of mind-wandering or task-unrelated thought. In contrast, the frontal-parietal network (FPN) and visual network (VS) are involved in tasks with external stimuli. However, it is not clear how these functional network interactions support these two different processes - mind-wandering and on-task - especially with regard to individual variation in the mind-wandering experience. In this study, we investigated the functional connectivity and modular structure among the DMN, FPN, and VS. Our results showed that, compared to the on-task period, mind-wandering was associated with increased DMN activity and increased DMN-VS connectivity. Moreover, mind-wandering was accompanied by a large number of transitional nodes, which expressed a diversity of brain regions. Intriguingly, the functional connectivity of the FPN and VS was strongly correlated with individual behavioral performance. Our findings highlight the individual variation of mind-wandering, which implies the importance of other complementary large-scale brain networks.

Neuroprotective effect of the ethanol extract of Artemisia capillaris on transient forebrain ischemia in mice via nicotinic cholinergic receptor / 中国天然药物

Artemisia capillaris Thunberg is a medicinal plant used as a traditional medicine in many cultures. It is an effective remedy for liver problems including hepatitis. Recent pharmacological reports have indicated that Artemisia species can exert various neurological effects. Previously, we reported a memory-enhancing effect of Artemisia species. However, the mechanisms underlying the neuroprotective effect of A. capillaris (AC) are still unknown. In the present study, we investigated the effect of an ethanol extract of AC on ischemic brain injury in a mouse model of transient forebrain ischemia. The mice were treated with AC for seven days, beginning one day before induction of transient forebrain ischemia. Behavioral deficits were investigated using the Y-maze. Nissl and Fluoro-jade B staining were used to indicate the site of injury. To determine the underlying mechanisms for the drug, we measured acetylcholinesterase activity. AC (200 mg·kg) treatment reduced transient forebrain ischemia-induced neuronal cell death in the hippocampal CA1 region. The AC-treated group also showed significant amelioration in the spontaneous alternation of the Y-maze test performance, compared to that in the untreated transient forebrain ischemia group. Moreover, AC treatment showed a concentration-dependent inhibitory effect on acetylcholinesterase activity in vitro. Finally, the effect of AC on forebrain ischemia was blocked by mecamylamine, a nonselective nicotinic acetylcholine receptor antagonist. Our results suggested that in a model of forebrain ischemia, AC protected against neuronal death through the activation of nicotinic acetylcholine receptors.

Atlas of the Striatum and Globus Pallidus in the Tree Shrew: Comparison with Rat and Mouse / 神经科学通报·英文版

The striatum and globus pallidus are principal nuclei of the basal ganglia. Nissl- and acetylcholinesterase-stained sections of the tree shrew brain showed the neuroanatomical features of the caudate nucleus (Cd), internal capsule (ic), putamen (Pu), accumbens, internal globus pallidus, and external globus pallidus. The ic separated the dorsal striatum into the Cd and Pu in the tree shrew, but not in rats and mice. In addition, computer-based 3D images allowed a better understanding of the position and orientation of these structures. These data provided a large-scale atlas of the striatum and globus pallidus in the coronal, sagittal, and horizontal planes, the first detailed distribution of parvalbumin-immunoreactive cells in the tree shrew, and the differences in morphological characteristics and density of parvalbumin-immunoreactive neurons between tree shrew and rat. Our findings support the tree shrew as a potential model for human striatal disorders.

Cerebro constructor dinámico de significados: más allá de la lingüística computacional / Brain dynamic builder meanings: beyond computational linguistic

Desde la aparición del estudio del cerebro a partir de las redes neuronales artificiales de McCulloch & Pitts (1965) y la arquitectura cerebral de Von Neumann(1951), la explicación científica de cómo significamos el mundo sentó sus bases en la metáfora de la mente entendida como cerebro-computador (Chomsky,1965). Aun cuando el intento de abordar la cuestión del significado desde esta perspectiva fue auspicioso, hoy es posible encontrar obstáculos asociados a laconcepción estática de la representación, requiriendo una perspectiva que conciba el cerebro como un constructor dinámico de significados (Varela, Thompson& Rosch, 2005). En este artículo presentamos una revisión de tres paradigmas experimentales que conciben la mente como un sistema dinámico espaciotemporal,donde la neurodinámica, el componente N400 y la neuroimagen son los más utilizados en la actualidad en el estudio del significado.

Since the emergence of the study of the brain from artificial neural networks McCulloch & Pitts (1965) and brain Von Neumann architecture (1951), the scien-tific explanation of how mean the world laid its foundations in the metaphor of the mind understood as brain-computer (Chomsky, 1965). Although the attempt to address the questionof meaning from this perspective was auspicious, it is now possible to find obstacles associated with static conception of representation, required a perspective that sees the brain as a dynamic builder of meanings (Varela, Thompson & Rosch, 2005). We present a review of three experimental paradigms which conceive the mind as a space-time, dynamic system where neurodynamics, the N400 component and neuroimaging are the most used today in the study of meaning.

Las enfermedades ¿son solo padecimientos?: biomedicina, formas de atención "paralelas" y proyectos de poder / Is disease merely illness?: Biomedicine, "parallel" forms of care and power

Partiendo de la propuesta de Giovanni Berlinguer, de que los procesos de salud/enfermedad constituyen algunos de los principales espías de las contradicciones de un sistema, se describen en primer lugar algunos casos ocurridos en contextos capitalistas centrales y periféricos, así como en Estados denominados "socialistas reales", que permiten observar dicho papel. En segundo lugar, observamos los procesos y sobre todo las interpretaciones que se han desarrollado en América Latina y especialmente en México respecto del papel atribuido a la medicina tradicional en la identidad y pertenencia de los pueblos originarios, y que subrayan la incompatibilidad de las cosmovisiones indígenas con la biomedicina, analizando algunos proyectos que se impulsaron en términos de salud intercultural, y que concluyeron en su mayoría en fracasos, tanto desde el punto de vista de la salud, como político. Se subraya el contenido y la perspectiva casi exclusivamente ideológicos de dichos proyectos, y su poca relación con la realidad de los pueblos originarios. Por último, se trata de ver si la trayectoria de estas concepciones y programas de salud expresan y explican el notable repliegue que sufren desde hace casi diez años la mayoría de los movimientos étnicos en América Latina.

Following Giovanni Berlinguer's proposal that health/disease processes are one of the primary spies into the contradictions of a system, this article describes cases that occurred in central and peripheral capitalist contexts as well as in the so-called "real socialist" States that allow such a role to be seen. Secondly, we observe the processes and above all the interpretations developed in Latin America and especially Mexico regarding the role attributed to traditional medicine in the identity and sense of belonging of indigenous peoples, which emphasize the incompatibility of indigenous worldviews with biomedicine. To do so we analyze projects that were carried out under the notion of intercultural health, which in large part resulted in failure both in health and political terms. The almost entirely ideological content and perspective of these projects is highlighted, as is the scant relationship they hold with the reality of indigenous people. Lastly, the impact and role that the advance of these conceptualizations and health programs might have had in the disengagement experienced over the last nearly ten years in the ethnic movements of Latin America is considered.

Utilização dos serviços de atendimento odontológico hospitalar sob sedação e/ou anestesia geral por pessoas com necessidades especiais no SUS-MG, Brasil / Availability of hospital dental care services under sedation or general anesthesia for individuals with special needs in the Unified Health System for the State of Minas Gerais (SUS-MG), Brazil

O presente estudo identificou as características demográficas dos indivíduos e assistenciais do tratamento odontológico sob sedação e/ou anestesia geral em ambiente hospitalar no SUS-MG. Foram avaliadas todas as Autorizações de Internações Hospitalares (AIH) para o procedimento Tratamento Odontológico para Pacientes com Necessidades Especiais, de julho de 2011 a junho de 2012. Foram mensuradas variáveis demográficas e assistenciais dos atendimentos. Foram calculadas as taxas de internações por 10.000 habitantes e a cobertura assistencial realizada no estado de Minas Gerais e em cada uma das Regiões Ampliadas de Saúde. A análise descritiva das variáveis foi feita por meio de cálculo da frequência e medidas de tendência central e variabilidade. Foram avaliadas todas as 1.063 AIH pagas no período estudado, que representaram uma taxa de 0,54 internações por 10.000 habitantes. A maioria dos indivíduos era adulta, do sexo masculino, com diagnóstico de transtornos mentais ou comportamentais e residente em 27,7% dos municípios de Minas Gerais. Os procedimentos foram realizados em 39 municípios e a cobertura assistencial foi igual a 1,58%. O estudo revelou um perfil clássico do paciente atendido. Dificuldades em se estabelecer uma rede de atenção à saúde bucal foram identificadas.

This study identified the demographic characteristics of individuals and dental treatment care under sedation/general anesthesia in a hospital environment in the Unified Health System in the State of Minas Gerais (SUS-MG). All Hospitalization Authorizations (AIHs) for Dental Treatment for Patients with Special Needs procedures were evaluated between July 2011 and June 2012. Demographic and health care variables for treatment were also assessed. Hospitalization rates per 10,000 inhabitants, and health care coverage provided in the state of Minas Gerais and in each of the Broader Health Regions were calculated. Descriptive analysis of data was carried out by calculating the central trend and variability frequency and measurements. All 1,063 AIHs paid during the study period were evaluated, which is equivalent to a rate of 0.54 hospitalizations per 10,000 individuals. The majority of the patients were adult, male, diagnosed with mental or behavioral disorders and resident in 27.7% of the municipalities in Minas Gerais. The procedures were performed in 39 municipalities and the care coverage was equal to 1.58%. The study reveals a classic demographic and clinical profile of patient attendance. Difficulties in establishing a network of dental care were identified.

Cephalometric variables used to predict the success of interceptive treatment with rapid maxillary expansion and face mask. A longitudinal study

INTRODUCTION: Prognosis is the main limitation of interceptive treatment of Class III malocclusions. The interceptive procedures of rapid maxillary expansion (RME) and face mask therapy performed in early mixed dentition are capable of achieving immediate overcorrection and maintenance of facial and occlusal morphology for a few years. Individuals presenting minimal acceptable faces at growth completion are potential candidates for compensatory orthodontic treatment, while those with facial involvement should be submitted to orthodontic decompensation for orthognathic surgery. OBJECTIVES: To investigate cephalometric variables that might predict the outcomes of orthopedic treatment with RME and face mask therapy (FM). METHODS: Cephalometric analysis of 26 Class III patients (mean age of 8 years and 4 months) was performed at treatment onset and after a mean period of 6 years and 10 months at pubertal growth completion, including a subjective facial analysis. Patients was divided into two groups: success group (21 individuals) and failure group (5 individuals). Discriminant analysis was applied to the cephalometric values at treatment onset. Two predictor variables were found by stepwise procedure. RESULTS: Orthopedic treatment of Class III malocclusion may have unfavorable prognosis at growth completion whenever initial cephalometric analysis reveals increased lower anterior facial height (LAFH) combined with reduced angle between the condylar axis and the mandibular plane (CondAx.MP). CONCLUSION: The results of treatment with RME and face mask therapy at growth completion in Class III patients could be predicted with a probability of 88.5%. .

INTRODUÇÃO: a principal limitação do tratamento interceptivo das más oclusões de Classe III está no prognóstico. Os procedimentos interceptivos de expansão rápida da maxila e de tração reversa, adotados ao início da dentição mista, são capazes de propiciar sobrecorreção imediata e manutenção da morfologia facial e oclusal por alguns anos. Pacientes que, ao final do crescimento, apresentam, no mínimo, faces aceitáveis, são candidatos ao tratamento ortodôntico compensatório, ao passo que aqueles com comprometimento facial deveriam ser submetidos a tratamento ortodôntico descompensatório para cirurgia ortognática. OBJETIVO: investigar variáveis cefalométricas preditoras dos resultados do tratamento ortopédico com expansão rápida da maxila e tração reversa (ERM e TM). MÉTODOS: uma avaliação cefalométrica foi aplicada, ao início do tratamento, em 26 crianças com má oclusão de Classe III (média de idade de 8 anos e 4 meses). Após um período médio de 6 anos e 10 meses, ao final do crescimento pubertário. sob o crivo de uma análise facial subjetiva, foram constituídos dois grupos, sendo um grupo de sucesso (21 pacientes) e um grupo de insucesso (5 pacientes). Análise discriminante foi aplicada aos valores cefalométricos ao início do tratamento, por meio do procedimento stepwise, assim, identificamos duas variáveis preditoras. RESULTADOS: o tratamento ortopédico de uma má oclusão Classe III pode ter prognóstico desfavorável ao final do crescimento quando, nos registros cefalométricos iniciais, for observada uma altura facial anteroinferior aumentada (AFAI) associada a uma diminuição do ângulo entre o eixo condilar e o plano mandibular (CondAx.PM). CONCLUSÃO: os resultados para o final de crescimento de um tratamento com ERM e TM, para cada novo paciente com má oclusão de Classe III, poderiam ser previstos com uma probabilidade de acerto de 88,5%. .

Hardware Implementation of Numerical Simulation Function of Hodgkin-Huxley Model Neurons Action Potential Based on Field Programmable Gate Array / 生物医学工程学杂志

Neuron is the basic unit of the biological neural system. The Hodgkin-Huxley (HH) model is one of the most realistic neuron models on the electrophysiological characteristic description of neuron. Hardware implementation of neuron could provide new research ideas to clinical treatment of spinal cord injury, bionics and artificial intelligence. Based on the HH model neuron and the DSP Builder technology, in the present study, a single HH model neuron hardware implementation was completed in Field Programmable Gate Array (FPGA). The neuron implemented in FPGA was stimulated by different types of current, the action potential response characteristics were analyzed, and the correlation coefficient between numerical simulation result and hardware implementation result were calculated. The results showed that neuronal action potential response of FPGA was highly consistent with numerical simulation result. This work lays the foundation for hardware implementation of neural network.

Robustness analysis of adaptive neural network model based on spike timing-dependent plasticity / 生物医学工程学杂志

To explore the self-organization robustness of the biological neural network, and thus to provide new ideas and methods for the electromagnetic bionic protection, we studied both the information transmission mechanism of neural network and spike timing-dependent plasticity (STDP) mechanism, and then investigated the relationship between synaptic plastic and adaptive characteristic of biology. Then a feedforward neural network with the Izhikevich model and the STDP mechanism was constructed, and the adaptive robust capacity of the network was analyzed. Simulation results showed that the neural network based on STDP mechanism had good rubustness capacity, and this characteristics is closely related to the STDP mechanisms. Based on this simulation work, the cell circuit with neurons and synaptic circuit which can simulate the information processing mechanisms of biological nervous system will be further built, then the electronic circuits with adaptive robustness will be designed based on the cell circuit.

Induced pluripotent stem cells and neurological disease models / 生理学报

The availability of human stem cells heralds a new era for in vitro cell-based modeling of neurodevelopmental and neurodegenerative diseases. Adding to the excitement is the discovery that somatic cells of patients can be reprogrammed to a pluripotent state from which neural lineage cells that carry the disease genotype can be derived. These in vitro cell-based models of neurological diseases hold promise for monitoring of disease initiation and progression, and for testing of new drug treatments on the patient-derived cells. In this review, we focus on the prospective applications of different stem cell types for disease modeling and drug screening. We also highlight how the availability of patient-specific induced pluripotent stem cells (iPS cells) offers a unique opportunity for studying and modeling human neurodevelopmental and neurodegenerative diseases in vitro and for testing small molecules or other potential therapies for these disorders. Finally, the limitations of this technology from the standpoint of reprogramming efficiency and therapeutic safety are discussed.

Changes of response patterns to excitatory stimuli of different intensities: a model-based study of cochlear nucleus neurons / 南方医科大学学报

<p><b>OBJECTIVE</b>The cochlear nucleus (CN) neurons show 3 principal response patterns to short tone bursts, namely the primary-like, chopper and onset response patterns. We previously established an excitatory model to simulate the response patterns of CN neurons to stimuli. In this study, we aimed to investigate the effects of excitatory intensity on the CN neuron response patterns and explore the role of inhibitory inputs under normal physiological conditions.</p><p><b>METHODS</b>Based on the platform of Matlab and the excitatory model derived from the integrate-and-fire model, we altered the intensity of excitatory inputs in dB range and obtained the histograms to analyze the changes in the response patterns of the neurons using OriginPro 7.5 data analysis software.</p><p><b>RESULTS</b>The original primary-like response pattern of the neurons did not vary significantly while the chopper and onset response patterns changed into primary-like responses with the increase of the excitatory input intensity. But this response pattern alteration as a result of excitatory input intensity changes was rarely observed under normal physiological conditions.</p><p><b>CONCLUSIONS</b>The CN neurons receive balanced excitatory and inhibitory inputs, which stabilize the neuronal membrane potential within a limited range. The balanced inhibitory inputs decide the response pattern of a given neuron.</p>