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1.
Inferior temporal (IT) cortex is critical for visual memory, but it is not known how IT neurons retain memories while new information is streaming into the visual system. Single neurons were therefore recorded from IT cortex of two rhesus monkeys performing tasks that required them to hold items in memory while concurrently viewing other items. The neuronal response to an incoming visual stimulus was attenuated if it matched a stimulus actively held in working memory, even when several other stimuli intervened. The neuronal response to novel stimuli declined as the stimuli became familiar to the animal. IT neurons appear to function as adaptive mnemonic "filters" that preferentially pass information about new, unexpected, or not recently seen stimuli. 相似文献
2.
To find a target object in a crowded scene, a face in a crowd for example, the visual system might turn the neural representation of each object on and off in a serial fashion, testing each representation against a template of the target item. Alternatively, it might allow the processing of all objects in parallel but bias activity in favor of those neurons that represent critical features of the target, until the target emerges from the background. To test these possibilities, we recorded neurons in area V4 of monkeys freely scanning a complex array to find a target defined by color, shape, or both. Throughout the period of searching, neurons gave enhanced responses and synchronized their activity in the gamma range whenever a preferred stimulus in their receptive field matched a feature of the target, as predicted by parallel models. Neurons also gave enhanced responses to candidate targets that were selected for saccades, or foveation, reflecting a serial component of visual search. Thus, serial and parallel mechanisms of response enhancement and neural synchrony work together to identify objects in a scene. To find a target object in a crowded scene, a face in a crowd for example, the visual system might turn the neural representation of each object on and off in a serial fashion, testing each representation against a template of the target item. Alternatively, it might allow the processing of all objects in parallel but bias activity in favor of those neurons that represent critical features of the target, until the target emerges from the background. To test these possibilities, we recorded neurons in area V4 of monkeys freely scanning a complex array to find a target defined by color, shape, or both. Throughout the period of searching, neurons gave enhanced responses and synchronized their activity in the gamma range whenever a preferred stimulus in their receptive field matched a feature of the target, as predicted by parallel models. Neurons also gave enhanced responses to candidate targets that were selected for saccades, or foveation, reflecting a serial component of visual search. Thus, serial and parallel mechanisms of response enhancement and neural synchrony work together to identify objects in a scene. 相似文献
3.
R H Wurtz 《Science (New York, N.Y.)》1968,162(858):1148-1150
While awake, unanesthetized monkeys held their eyes stationary, a motionless or slowly moving stimulus falling on the receptive field of striate cortex neurons produced an excitatory response. When a rapid eye movement was made across the same stimulus, many of these neurons continued to give an excitatory response. But the discharge of other neurons was unchanged or was suppressed during the eye movement. 相似文献
4.
TA Jarrell Y Wang AE Bloniarz CA Brittin M Xu JN Thomson DG Albertson DH Hall SW Emmons 《Science (New York, N.Y.)》2012,337(6093):437-444
In order to understand the nervous system, it is necessary to know the synaptic connections between the neurons, yet to date, only the wiring diagram of the adult hermaphrodite of the nematode Caenorhabditis elegans has been determined. Here, we present the wiring diagram of the posterior nervous system of the C. elegans adult male, reconstructed from serial electron micrograph sections. This region of the male nervous system contains the sexually dimorphic circuits for mating. The synaptic connections, both chemical and gap junctional, form a neural network with four striking features: multiple, parallel, short synaptic pathways directly connecting sensory neurons to end organs; recurrent and reciprocal connectivity among sensory neurons; modular substructure; and interneurons acting in feedforward loops. These features help to explain how the network robustly and rapidly selects and executes the steps of a behavioral program on the basis of the inputs from multiple sensory neurons. 相似文献
5.
The neural encoding of serial order was studied in the motor cortex of monkeys performing a context-recall memory scanning task. Up to five visual stimuli were presented successively on a circle (list presentation phase), and then one of them (test stimulus) changed color; the monkeys had to make a single motor response toward the stimulus that immediately followed the test stimulus in the list. Correct performance in this task depends on memorization of the serial order of the stimuli during their presentation. It was found that changes in neural activity during the list presentation phase reflected the serial order of the stimuli; the effect on cell activity of the serial order of stimuli during their presentation was at least as strong as the effect of motor direction on cell activity during the execution of the motor response. This establishes the serial order of stimuli in a motor task as an important determinant of motor cortical activity during stimulus presentation and in the absence of changes in peripheral motor events, in contrast to the commonly held view of the motor cortex as just an "upper motor neuron." 相似文献
6.
Networks adapt to environmental demands by switching between distinct dynamical behaviors. The activity of frontal-lobe neurons during two-interval discrimination tasks is an example of these adaptable dynamics. Subjects first perceive a stimulus, then hold it in working memory, and finally make a decision by comparing it with a second stimulus. We present a simple mutual-inhibition network model that captures all three task phases within a single framework. The model integrates both working memory and decision making because its dynamical properties are easily controlled without changing its connectivity. Mutual inhibition between nonlinear units is a useful design motif for networks that must display multiple behaviors. 相似文献
7.
The extent to which synaptic activity can signal a sensory stimulus limits the information available to a neuron. We determined the contribution of individual synapses to sensory representation by recording excitatory postsynaptic currents (EPSCs) in cerebellar granule cells during a time-varying, quantifiable vestibular stimulus. Vestibular-sensitive synapses faithfully reported direction and velocity, rather than position or acceleration of whole-body motion, via bidirectional modulation of EPSC frequency. The lack of short-term synaptic dynamics ensured a highly linear relationship between velocity and charge transfer, and as few as 100 synapses provided resolution approaching psychophysical limits. This indicates that highly accurate stimulus representation can be achieved by small networks and even within single neurons. 相似文献
8.
B Bridgeman 《Science (New York, N.Y.)》1972,178(65):1106-1108
Some neurons in the visual cortex of awake monkeys visually tracking a moving target showed receptive fields that were excited only by stimulus motion relative to a background, while other neurons responded to any kind of stimulus motion. This result was found with two methods, one in which tracking eye movements were identical in both relative-motion and absolute-motion conditions, and another in which stimulus motions on the retina were identical in both conditions. This response pattern can differentiate translation of the retinal image during eye movement from motion of objects in the world. 相似文献
9.
Eye-head coordination was investigated by recording from the neck and eye muscles in monkeys. The results show that (i) during eye-head turning, neural activity reaches the neck muscles before the eye muscles, and (ii) all agonist neck muscles are activated simultaneously regardless of the initial head position. Since overt movement of the eyes precedes that of the head, it was concluded that the central neural command initiates the eye-head sequence but does not specify its serial order. Furthermore, it was determined that the compensatory eye movement is not initiated centrally but instead is dependent upon reflex activation arising from movement of the head. 相似文献
10.
Information delivery and the sensory evoked potential 总被引：9，自引：0，他引：9
The waveform of evoked responses recorded from human scalp is not determined solely by the physical eliciting stimulus, but also varies as a function of the effective information provided by the stimulus. There is a positive component whose latency is determined by the point in time at which ambiguity is reduced, and whose shape and amplitude are influenced by whether it is the presence or absence of an external event which delivers the information. 相似文献
11.
"Tactile" stimulus intensity: information transmission by relay neurons in different trigeminal nuclei 总被引：4，自引：0，他引：4
Comparison of the information transmitted about the intensity of a steady "tactile" stimulus applied to facial skin by single trigemino-thalamic neurons in nucleus oralis and nucleus caudalis indicates that little information loss occurs at the medial lemniscal synaptic relay (nucleus oralis), but that it is gross within the nucleus caudalis. 相似文献
12.
Reading a neural code 总被引：19，自引：0，他引：19
W Bialek F Rieke R R de Ruyter van Steveninck D Warland 《Science (New York, N.Y.)》1991,252(5014):1854-1857
Traditional approaches to neural coding characterize the encoding of known stimuli in average neural responses. Organisms face nearly the opposite task--extracting information about an unknown time-dependent stimulus from short segments of a spike train. Here the neural code was characterized from the point of view of the organism, culminating in algorithms for real-time stimulus estimation based on a single example of the spike train. These methods were applied to an identified movement-sensitive neuron in the fly visual system. Such decoding experiments determined the effective noise level and fault tolerance of neural computation, and the structure of the decoding algorithms suggested a simple model for real-time analog signal processing with spiking neurons. 相似文献
13.
通过USB数据线将WAVECOM GSM调制解调器与微型计算机相连接,在程序中以C#语言为开发工具打开将虚拟的串口COM3,使用AT指令实现了对中文短消息的发送和接收。本文主要介绍了将发送短消息PDU模式串的合成与将接收到的短消息PDU模式串解析成可直接阅读的中英文字符的实现过程,以及短消息发送和接收的处理流程,最后给出了实验的结果。 相似文献
14.
Neuronal correlates of subjective visual perception 总被引：10，自引：0，他引：10
Neuronal activity in the superior temporal sulcus of monkeys, a cortical region that plays an important role in analyzing visual motion, was related to the subjective perception of movement during a visual task. Single neurons were recorded while monkeys (Macaca mulatta) discriminated the direction of motion of stimuli that could be seen moving in either of two directions during binocular rivalry. The activity of many neurons was dictated by the retinal stimulus. Other neurons, however, reflected the monkeys' reported perception of motion direction, indicating that these neurons in the superior temporal sulcus may mediate the perceptual experience of a moving object. 相似文献
15.
Neurons in inferotemporal cortex (area TE) of the monkey had visual receptive fields which were very large (greater than 10 by 10 degrees) and almost always included the fovea. Some extended well into both halves of the visual field, while others were confined to the ipsilateral or contralateral side. These neurons were differentially sensitive to several of the following dimensions of the stimulus: size and shape, color, orientation, and direction of movement. 相似文献
16.
基于希尔伯特变换(Hilbert),设计了害虫自动计数和远程发布预警系统。系统主要由杀虫灯、采集卡、变压器、PC机、可编程逻辑控制器(PLC)、路由器等硬件设备组成,运行时,杀虫灯高压网端的电压信号经变压器降压,采集卡采集降压后的杀虫网电压,采集卡通过USB口与PC机相连,PLC通过串口与PC机相连。用Lab VIEW软件作为平台,对采集到的信号进行Hilbert变换,得到信号的瞬时幅值,当瞬时幅值小于设定值时,通过串口给PLC发送Modbus指令,PLC接收到指令后对相应寄存器进行计数。利用PLC和My SCADA组态软件对PLC寄存器数据进行远程发布,手机端、远程桌面端都可监测现场害虫计数值。对采集到的714只害虫触网扰动信号进行分析,从中任意选4组共7个扰动信号进行演示,结果系统能准确识别7个扰动区,并通过手机端和远程桌面端显示。 相似文献
17.
Oscillator neurons in crustacean ganglia 总被引：2，自引：0，他引：2
M Mendelson 《Science (New York, N.Y.)》1971,171(976):1170-1173
The motor rhythm of ventilation in hermit crabs and lobsters appears to be controlled by a pair of neurons, one in each half of the subesophageal ganglion. Their membrane potentials oscillate and upon depolarization and hyperpolarization elicit spiking in two pools of motor neurons on each side, without spikes in the oscillator neurons themselves. The fact that higher order (command) interneurons can control the rate of the oscillator by means of a smoothly graded input lends support to the idea that oscillator neurons respond periodically to a constant ionic stimulus. 相似文献
18.
A fundamental aspect of visuomotor behavior is deciding where to look or move next. Under certain conditions, the brain constructs an internal representation of stimulus location on the basis of previous knowledge and uses it to move the eyes or to make other movements. Neuronal responses in primary visual cortex were modulated when such an internal representation was acquired: Responses to a stimulus were affected progressively by sequential presentation of the stimulus at one location but not when the location was varied randomly. Responses of individual neurons were spatially tuned for gaze direction and tracked the Bayesian probability of stimulus appearance. We propose that the representation arises in a distributed cortical network and is associated with systematic changes in response selectivity and dynamics at the earliest stages of cortical visual processing. 相似文献
19.
Area 5 in the parietal lobe of the primate brain is thought to be involved in monitoring the posture and movement of the body. In this study, neurons in monkey area 5 were found to encode the position of the monkey's arm while it was covered from view. The same neurons also responded to the position of a visible, realistic false arm. The neurons were not sensitive to the sight of unrealistic substitutes for the arm and were able to distinguish a right from a left arm. These neurons appear to combine visual and somatosensory signals in order to monitor the configuration of the limbs. They could form the basis of the complex body schema that we constantly use to adjust posture and guide movement. 相似文献
20.
朱勇 《大连水产学院学报》2002,17(2):146-150
微型计算机在控制应用中，由于使用环境存在着各种各样的瞬间干扰，有时会引起控制程序的混乱而造成系统失控，为提高程序运行的可靠性，笔者提出一种操作码监督法用来监督程序的运行，一旦执行了错误指令，监视电路能及时发现，并根据控制系统的特性，由相应的非屏蔽中断程序进行相应的处理，使控制程序自恢复，系统复位或停机报警。 相似文献