A Physiological Mechanism for Hebb's Postulate of Learning

Stent, Gunther S.

doi:10.1073/pnas.70.4.997

Cited by 646 publications

(309 citation statements)

References 24 publications

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“…Other critical variables include the state of activation of the postsynaptic neuron and, in particular, the degree of temporal correlation between pre-and postsynaptic activation Singer, 1979, 1981;Fr6gnac et al 1988;Greuel et al 1988). The use-dependent modifications of excitatory transmission seem to f o lr ules which closely resemble those postulated by Hebb (1949) and Stent (1973) for adaptive neuronal connections (Rauschecker and Singer, 1981). As summarized in Fig.…”

Section: Scene Segmentation and Figure-ground Segregationsupporting

confidence: 49%

The Formation of Cooperative Cell Assemblies in the Visual Cortex

Singer

1991

Neuronal Cooperativity

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SummaryDuring a critical period of postnatal development of the mammalian visual cortex, synaptic connections are susceptible to use-dependent modifications. Synaptic connections strengthen if pre-and postsynaptic elements are active simultaneously and postsynaptic depolarization is sufficient to allow for the activation of A'-methyl-D-aspartate (NMDA)-receptor-gated conductances. By contrast, synaptic gain decreases if postsynaptic activation exceeds a critical threshold and presynaptic afferents are not capable of activating NMDAreceptor-dependent conductances. These processes lead to selective stabilization of connections between neuronal elements which often exhibit correlated activity and thus modify connectivity according to functional criteria. It is suggested that such experience-dependent selection of circuits serves different purposes at different levels of visual processing. At the input stage to the striate cortex it contributes to optimize the match between the representations of the two eyes. At a later stage of processing it participates in the development of selective connections between cortical columns and thereby serves to establish neuronal representations for frequently occurring constellations of features.Use-dependent changes of synaptic gain can also be induced in the mature visual cortex. These modifications follow the same rules as those occurring during early development and appear to depend on similar molecular mechanisms. However, in the adult the changes of synaptic gain do not seem to be followed by major rearrangements of connectivity. This suggests developmental alterations in mechanisms responsible for growth, removal and stabilization of synaptic connections. Actually, many of the cellular mechanisms thought to be involved in usedependent synaptic plasticity change during development but it is still unclear which of them are responsible for the definitive stabilization of functionally confirmed pathways. Functions requiring use-dependent selection of neuronal connections Fusion and stereopsisHigher mammals and humans, which have frontally positioned eyes with overlapping visual fields, can fuse the images of the two eyes and compute from their differences the distance of objects in space. The basis for this function are J|eurons in the visual cortex which possess two receptive fields, one in each eye,

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Section: Scene Segmentation and Figure-ground Segregationsupporting

confidence: 49%

The Formation of Cooperative Cell Assemblies in the Visual Cortex

Singer

1991

Neuronal Cooperativity

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“…Depending on whether prc-and postsynaptic activities are correlated in time, synapses may be stabilized or d&ted (Hebb. 1949: Stent. 1973.…”

Section: Discussionmentioning

confidence: 99%

Enhanced activation of NMDA receptor responses at the immature retinogeniculate synapse

1994

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The maturation of retinogeniculate excitatory transmission and intrathalamic inhibition was studied in slices of the dorsal LGN obtained from ferrets during the first 2 postnatal months. Response to optic tract stimulation at neonatal ages consisted of slow EPSPs lasting several hundred milliseconds. Application of the NMDA receptor antagonist D-(-)-2-amino-5-phosphonovaleric acid (D-APV) during the first 2 postnatal weeks resulted in EPSPs that were reduced in peak amplitude and dramatically curtailed in duration, indicating that NMDA receptors participate strongly in retinogeniculate transmission at the immature synapse. Gradually, EPSPs became shorter in duration such that after the second postnatal week, the retinogeniculate EPSPs were only a few milliseconds in duration. At this late stage of development responses were remarkably less affected by application of D-APV. These changes in contribution of NMDA receptors to retinogeniculate transmission were found to be due to the development of strong IPSPs, the result of gradual maturation of activation of GABAergic inhibition. Indeed, application of bicuculline methiodide to block GABAA receptor- mediated IPSPs strongly enhanced the NMDA component of the EPSPs in more mature cells. The voltage dependence and kinetics of NMDA-induced excitatory postsynaptic currents (NMDA EPSCs) were characterized by voltage-clamp recordings after blocking AMPA/kainate receptors with 6- cyano-7-nitroquinoxaline-2,3-dione and GABAA receptors wit' bicuculline methiodide. The voltage dependence of the NMDA EPSCs remained unaltered with age. During the first postnatal month the kinetic properties of the NMDA EPSCs also remained unaltered, but a reduction in EPSC duration was observed within the following weeks, well after the critical period of anatomical reorganization.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Synaptic connections typically follow correlation-based learning rules such that connections between neurons with correlated activity are strengthened and connections between uncorrelated neurons are weakened (Bi and Poo, 2001;Hebb, 1949;Stent, 1973). These changes in synaptic 0378-5955/$ -see front matter Ó 2004 Elsevier B.V. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%

Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex

Pandya¹,

Moucha²,

Engineer³

et al. 2005

Hearing Research

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Correlation-based synaptic plasticity provides a potential cellular mechanism for learning and memory. Studies in the visual and somatosensory systems have shown that behavioral and surgical manipulation of sensory inputs leads to changes in cortical organization that are consistent with the operation of these learning rules. In this study, we examine how the organization of primary auditory cortex (A1) is altered by tones designed to decrease the average input correlation across the frequency map. After one month of separately pairing nucleus basalis stimulation with 2 and 14 kHz tones, a greater proportion of A1 neurons responded to frequencies below 2 kHz and above 14 kHz. Despite the expanded representation of these tones, cortical excitability was specifically reduced in the high and low frequency regions of A1, as evidenced by increased neural thresholds and decreased response strength. In contrast, in the frequency region between the two paired tones, driven rates were unaffected and spontaneous firing rate was increased. Neural response latencies were increased across the frequency map when nucleus basalis stimulation was associated with asynchronous activation of the high and low frequency regions of A1. This set of changes did not occur when pulsed noise bursts were paired with nucleus basalis stimulation. These results are consistent with earlier observations that sensory input statistics can shape cortical map organization and spike timing.

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A Physiological Mechanism for Hebb's Postulate of Learning

Cited by 646 publications

References 24 publications

The Formation of Cooperative Cell Assemblies in the Visual Cortex

The Formation of Cooperative Cell Assemblies in the Visual Cortex

Enhanced activation of NMDA receptor responses at the immature retinogeniculate synapse

Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex

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