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Learning cortical topography from spatiotemporal stimuli

BIOLOGICAL CYBERNETICS 2000年第2期82卷 173-187页

作者： Wiemer, J Spengler, F Joublin, F Stagge, P Wacquant, S Ruhr Univ Bochum Inst Neuroinformat D-44780 Bochum Germany

Stimulus representation is a functional interpretation of early sensory cortices. Early sensory cortices are subject to stimulus-induced modifications. Common models for stimulus-induced learning within topographic representations are based on the stimuli's spatial structure and probability distribution. Furthermore, we argue that average temporal stimulus distances reflect the stimuli's relatedness. As topographic representations reflect the stimuli's relatedness, the temporal structure of incoming stimuli is important for the learning in cortical maps. Motivated by recent neurobiological findings, we present an approach of cortical self-organization that additionally takes temporal stimulus aspects into account. The proposed model transforms average interstimulus intervals into representational distances. Thereby, neural topography is related to stimulus dynamics. This offers a new time-based interpretation of cortical maps. Our approach is based on a wave-like spread of cortical activity. Interactions between dynamics and feedforward activations lead to shifts of neural activity. The psychophysical saltation phenomenon map represent an analogue to the shifts proposed here. With regard to cortical plasticity, we offer an explanation for neurobiological findings that other models cannot explain. Moreover? we predict cortical reorganizations under new experimental, spatiotemporal conditions. With regard to psychophysics, we relate the saltation phenomenon to dynamics and interaction in early sensory cortices and predict further effects in the perception of spatiotemporal stimuli.

关键词：脑图计算机模拟类人猿亚目动力学学习/生理学模型神经学神经网/生理学神经元可塑性/生理学神经元/生理学物理刺激心理物理学躯体感觉皮质/细胞学躯体感觉皮质/生长和发育躯体感觉皮质/生理学空间知觉/生理学突触/生理学时间因素触觉/生理学动物

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Role of AMPA receptor cycling in synaptic transmission and plasticity

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NEURON 1999年第3期24卷 649-658页

作者： Lüscher, C Xia, HH Beattie, EC Carroll, RC von Zastrow, M Malenka, RC Nicoll, RA Univ Calif San Francisco Dept Cellular & Mol Pharmacol San Francisco CA 94143 USA Univ Calif San Francisco Dept Physiol San Francisco CA 94143 USA Univ Calif San Francisco Dept Psychiat San Francisco CA 94143 USA

Compounds known to disrupt exocytosis or endocytosis were introduced into CA1 pyramidal cells while monitoring excitatory postsynaptic currents (EPSCs). Disrupting exocytosis or the interaction of GluR2 with NSF caused a gradual reduction in the AMPAR EPSC, while inhibition of endocytosis caused a gradual increase in the AMPAR EPSC. These manipulations had no effect on the NMDAR EPSC but prevented the subsequent induction of LTD. These results suggest that AMPARs, but not NMDARs, cycle into and out of the synaptic membrane at a rapid rate and that certain forms of synaptic plasticity may utilize this dynamic process.

关键词：载体蛋白质类/生理学胞吞作用/生理学胞吐作用/生理学长时程增强/生理学 N-乙基顺丁烯二酰亚胺-敏感蛋白质类神经元可塑性/生理学大鼠 Sprague-Dawley 受体 AMPA/生理学突触/生理学突触传递/生理学膜泡运输蛋白质类动物大鼠

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Plasticity in the distribution of the red nucleus output to forearm muscles after unilateral lesions of the pyramidal tract

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JOURNAL OF NEUROPHYSIOLOGY 2000年第5期83卷 3147-3153页

作者： Belhaj-Saïf, A Cheney, PD Univ Kansas Med Ctr Mental Retardat & Human Dev Res Ctr Kansas City KS 66160 USA Univ Kansas Med Ctr Dept Mol & Integrat Physiol Kansas City KS 66160 USA

It has been hypothesized that the magnocellular red nucleus (RNm) contributes to compensation for motor impairments associated with lesions of the pyramidal tract. To test this hypothesis, we used stimulus triggered averaging (StTA) of electromyographic (EMG) activity to characterize changes in motor output from the red nucleus after lesions of the pyramidal tract. Three monkeys were trained to perform a reach and prehension task. EMG activity was recorded from 11 forearm muscles including one elbow, five wrist, and five digit muscles. Microstimulation (20 mu A at 20 Hz) was delivered throughout the movement task to compute StTAs. Two monkeys served as controls. In a third monkey, 65% of the left pyramidal tract had been destroyed by an electrolytic lesion method five years before recording. The results demonstrate a clear pattern of postlesion reorganization in red nucleus-mediated output effects on forearm muscles. The normally prominent. extensor preference in excitatory output from the RNm (92% in extensors) was greatly diminished in the lesioned monkey (59%). Similarly, suppression effects, which are normally much more prominent in flexor than in extensor muscles (90% in flexors), were also more evenly distributed after recovery from pyramidal tract lesions. Because of the limited excitatory output from the RNm to flexor muscles that normally exists, loss of corticospinal output would leave control of flexors particularly weak. The changes in RNm organization reported in this study would help restore function to flexor muscles. These results support the hypothesis that the RNm is capable of reorganization that contributes to the recovery of forelimb motor function after pyramidal tract lesions.

关键词：动作电位/生理学肘/生理学电刺激电极植入肌电描记术指/生理学前臂/生理学猕猴微电极肌骨骼/神经支配肌骨骼/生理学神经元可塑性/生理学锥体束/生理学锥体束/外科学反应时间/生理学红核/生理学腕/生理学动物男(雄)性

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An associational model of birdsong sensorimotor learning I. Efference copy and the learning of song syllables

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JOURNAL OF NEUROPHYSIOLOGY 2000年第3期84卷 1204-1223页

作者： Troyer, TW Doupe, AJ Univ Calif San Francisco Dept Psychiat San Francisco CA 94143 USA Univ Calif San Francisco Dept Physiol San Francisco CA 94143 USA Univ Calif San Francisco WM Keck Ctr Integrat Neurosci San Francisco CA 94143 USA Univ Calif San Francisco Sloan Ctr theoret Neurobiol UCSF San Francisco CA 94143 USA

Birdsong learning provides an ideal model system for studying temporally complex motor behavior. Guided by the well-characterized functional anatomy of the song system, we have constructed a computational model of the sensorimotor phase of song learning. Our model uses simple Hebbian and reinforcement learning rules and demonstrates the plausibility of a detailed set of hypotheses concerning sensory-motor interactions during song learning. The model focuses on the motor nuclei HVc and robust nucleus of the archistriatum (RA) of zebra finches and incorporates the long-standing hypothesis that a series of song nuclei, the Anterior Forebrain Pathway (AFP), plays an important role in comparing the bird's own vocalizations with a previously memorized song, or "template." This "AFP comparison hypothesis" is challenged by the significant delay that would be experienced by presumptive auditory feedback signals processed in the AFP. We propose that the AFP does not directly evaluate auditory feedback, but instead, receives an internally generated prediction of the feedback signal corresponding to each vocal gesture, or song "syllable." This prediction, or "efference copy," is learned in HVc by associating premotor activity in RA-projecting HVc neurons with the resulting auditory feedback registered within AFP-projecting HVc neurons. We also demonstrate how negative feedback "adaptation" can be used to separate sensory and motor signals within HVc. The model predicts that motor signals recorded in the AFP during singing carry sensory information and that the primary role for auditory feedback during song learning is to maintain an accurate efference copy. The simplicity of the model suggests that associational efference copy learning may be a common strategy for overcoming feedback delay during sensorimotor learning.

关键词：算法联想学习/生理学计算机模拟反馈模型神经学神经通路/生理学神经元可塑性/生理学前脑/生理学精神运动性行为/生理学反应时间/生理学强化(心理学) 鸣禽鸟/生理学声音突触传递/生理学发声动物/生理学动物

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Neuropharmacology and linguistic neuroplasticity

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BRAIN AND LANGUAGE 2000年第1期71卷 96-101页

作者： Hughes, JD Jacobs, DH Heilman, KM Uniformed Serv Univ Hlth Sci Dept Neurol Bethesda MD 20814 USA Univ Florida Coll Med Dept Neurol Gainesville FL 32611 USA

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Delayed and blunted induction of mRNA for tissue plasminogen activator in the brain of old rats following pentylenetetrazole-induced seizure activity

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JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES 2000年第5期55卷 B242-B248页

作者： Popa-Wagner, A Fischer, B Platt, D Schmoll, H Kessler, C Ernst Moritz Arndt Univ Greifswald Dept Neurol D-17487 Greifswald Germany Univ Erlangen Nurnberg Inst Gerontol D-8520 Erlangen Germany

The ability of the rodent brain to support plasticity-related phenomena declines with increasing age, Here we investigated the extent to which old rats retain the rapacity to initiate transcription for immediate early genes, particularly as it relates to brain plasticity, in response to a strong stimulus. The intraperitoneal administration of pentylenetetrazole (PTZ) to rats of various ages evoked tonic-clonic seizures. Using an RNA gel-blot and in situ hybridization analysis, we found that 1 hour after the onset of seizure, messenger RNA (mRNA) for tissue plasminogen activator (TPA) was increased similar to 3.7-fold in the hippocampi of 3-month-old rats. The levels;of TPA mRNA in the hippocampi and cortices of 3-month-old rats returned to control levels by 3 hours after PTZ administration, The levels of TPA mRNA increased 2.5-fold in the hippocampi of 18-month-old rats and 1.8-fold in the brains of the 28-month-old-rats at 3 hours and returned to basal levels by 15 hours following PTZ treatment. Quantitatively;similar increases were calculated for the cortex. At peak induction the transcripts were localized throughout the cortical layers of the 3-moth-old rats, whereas the TPA mRNA expression was restricted to cortical layer V of the older rats. Our results suggest that although the aging brain retains the capacity to respond to chemically induced seizures, the induction of TPA mRNA is temporarily delayed and the levels are diminished with increasing age. Because TPA has been implicated in neuronal plasticity, this finding suggests that immediate early genes are important factors in the limited plasticity of the aging brain.

关键词：衰老/生理学方差分析印迹法 RNA 脑/酶学酶诱导基因表达原位杂交神经元可塑性/生理学戊四唑 RNA 信使/代谢大鼠 Sprague-Dawley 发作/化学诱导发作/遗传学发作/病理生理学组织型纤溶酶原激活物/生物合成组织型纤溶酶原激活物/遗传学组织型纤溶酶原激活物/生理学动物女(雌)性大鼠

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Muscarinic acetylcholine receptors in the hippocampus, neocortex and amygdala: A review of immunocytochemical localization in relation to learning and memory

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PROGRESS IN NEUROBIOLOGY 1999年第5期58卷 409-471页

作者： Van der Zee, EA Luiten, PGM Univ Groningen Dept Zool NL-9750 AA Haren Netherlands Univ Groningen Dept Anim Physiol NL-9750 AA Haren Netherlands

Immunocytochemical mapping studies employing the extensively used monoclonal antimuscarinic acetylcholine: receptor (mAChR) antibody M35 are reviewed;sd. We focus on three neuronal muscarinic cholinoceptive substrates. which are target regions of the cholinergic basal forebrain system intimately involved in cognitive functions: the hippocampus: neocortex: and amygdala. Thr distribution and neurochemistry of mAChR-immunoreactive cells as wall as behaviorally induced alterations in mAChR-immunoreactivity;(ir) are described in detail. M35(+) neurons are viewed as cells actively engaged in neuronal functions in which the cholinergic system is typically involved. Phosphorylation and subsequent internalization of muscarinic receptors determine the immunocytochemical outcome, and hence M35 as a tool to visualize muscarinic receptors is less suitable for detection of the entire pool of mAChRs in the central nervous system (CNS). Instead, M35 is sensitive to and capable of detecting alterations in the physiological condition of muscarinic receptors. Therefore. M35 is an excellent tool to, localize alterations in cellular cholinoceptivity in the CNS. M35-ir is not only deter mined by acetylcholine (ACh), but by any substance that changes the phosphorylation/internalization state of the mAChR. An important consequence of this proposition is that other neurotransmitters than ACh (especially;glutamate) can regulate M35-ir and the cholinoceptive state of a neuron. and hence the functional properties of a neuron. One of the primary objectives of this review is to provide a synthesis of our data and literature data on mAChR-ir. We propose a hypothesis: for the role of muscarinic receptors in learning and memory in terms of modulation between learning and recall states of brain areas at the postsynaptic level as studied by way of immunocytochemistry employing the monoclonal antibody M35. (C) 1999 Elsevier Science Ltd. All rights reserved.

关键词：年龄因素杏仁核/血液供给杏仁核/化学脑动脉/代谢脑静脉/代谢谷氨酸脱羧酶/分析海马/血液供给海马/化学免疫组织化学中间神经元/化学学习/生理学记忆/生理学新皮质/血液供给新皮质/化学神经元可塑性/生理学蛋白激酶C/分析受体毒蕈碱/分析受体毒蕈碱/历史受体毒蕈碱/超微结构动物历史 19世纪历史 20世纪人类

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Plasticity in adult cat visual cortex (area 17) following circumscribed monocular lesions of all retinal layers

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JOURNAL OF PHYSIOLOGY-LONDON 2000年第2期524卷 587-602页

作者： Calford, MB Wang, C Taglianetti, V Waleszczyk, WJ Burke, W Dreher, B Australian Natl Univ Psychobiol Lab Div Psychol Canberra ACT 0200 Australia Univ Queensland Vis Touch & Hearing Res Ctr Brisbane Qld 4072 Australia Univ Sydney Inst Biomed Res Dept Anat & Histol Sydney NSW 2006 Australia Univ Sydney Inst Biomed Res Dept Physiol Sydney NSW 2006 Australia M Nencki Inst Expt Biol PL-02093 Warsaw Poland

1. In eight adult cats intense, sharply circumscribed, monocular laser lesions were used to remove all cellular layers of the retina. The extents of the retinal lesions were subsequently confirmed with counts of cc-ganglion cells in retinal whole mounts;in some cases these revealed radial segmental degeneration of ganglion cells distal to the lesion. 2. Two to 24 weeks later, area 17 (striate cortex;V1) was studied electrophysiologically in a standard anaesthetized, paralysed (artificially respired) preparation. Recording single- or multineurone activity revealed extensive topographical reorganization within the lesion projection zone (LPZ). 3. Thus, with stimulation of the lesioned eye, about 75% of single neurones in the LPZ had 'ectopic' visual discharge fields which were displaced to normal retina in the immediate vicinity of the lesion. 4. The sizes of the ectopic discharge fields were not significantly different from the sizes of the normal discharge fields. Furthermore, binocular cells recorded from the LPZ, when stimulated via their ectopic receptive fields, exhibited orientation tuning and preferred stimulus velocities which were indistinguishable from those found when the cells were stimulated via the normal eye. 5. However, the responses to stimuli presented via ectopic discharge fields were generally weaker (lower peak discharge rates) than those to presentations via normal discharge fields, and were characterized by a lower-than-normal upper velocity limit. 6. Overall, the properties of the ectopic receptive fields indicate that cortical mechanisms rather than it retinal 'periphery' effect underlie the topographic reorganization of area 17 following monocular retinal lesions.

关键词：诱发电位视觉/生理学功能偏侧化/生理学神经元可塑性/生理学定向力/生理学光刺激视网膜/解剖学和组织学视网膜/细胞学视网膜/生理学视觉单眼/生理学视皮质/解剖学和组织学视皮质/细胞学视皮质/生理学视野/生理学视通路/细胞学视通路/生理学动物猫

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Plasticity in the enteric nervous system

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GASTROENTEROLOGY 1999年第6期117卷 1438-1458页

作者： Giaroni, C De Ponti, F Cosentino, M Lecchini, S Frigo, G Univ Pavia Dept Internal Med & Therapeut I-27100 Pavia Italy Univ Bologna Dept Pharmacol Bologna Italy Univ Insubria Pharmacol Lab Varese Italy

Enteric ganglia can maintain integrated functions, such as the peristaltic reflex, in the absence of input from the central nervous system, which has a modulatory role. Several clinical and experimental observations suggest that homeostatic control of gut function in a changing environment may be achieved through adaptive changes occurring in the enteric ganglia, A distinctive feature of enteric ganglia, which may be crucial during the development of adaptive responses, is the vicinity of the final effector cells, which are an important source of mediators regulating cell growth. The aim of this review is to focus on the possible mechanisms underlying neuronal plasticity in the enteric nervous system and to consider approaches to the study of plasticity in this model. These include investigations of neuronal connectivity during development, adaptive mechanisms that maintain function after suppression of a specific neural input, and the possible occurrence of activity-dependent modifications of synaptic efficacy, which are thought to be important in storage of information in the brain. One of the applied aspects of the study of plasticity in the enteric nervous system is that knowledge of the underlying mechanisms may eventually enable us to develop strategies to correct neuronal alterations described in several diseases.

关键词：适应生物学衰老/生理学消化系统生理学现象肠神经系统/生长和发育肠神经系统/生理学环境神经元可塑性/生理学人类

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Structure, development, and plasticity of dendritic spines

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CURRENT OPINION IN NEUROBIOLOGY 1999年第3期9卷 343-348页

作者： Harris, KM Childrens Hosp Dept Neurol Div Neurosci Boston MA 02115 USA

Dendritic spines are distinguished by their shapes, subcellular composition, and synaptic receptor subtypes. Recent studies show that actin-dependent movements take place in spine heads, that spines emerge from stubby and shaft synapses after dendritic filopodia disappear, and that spines can form without synaptic activation, are maintained by optimal activation, and are lost with excessive activation or during degeneration.

关键词：脑/细胞学脑/生理学树突/生理学树突/超微结构神经元可塑性/生理学动物

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