Sherman SM, Guillery RW. On the actions that one nerve cell can have on another: distinguishing ‘drivers’ from ‘modulators’. Proc Natl Acad Sci USA 95: 7121-7126

University of Wisconsin–Madison, Madison, Wisconsin, United States
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 07/1998; 95(12):7121-6. DOI: 10.1073/pnas.95.12.7121
Source: PubMed


When one nerve cell acts on another, its postsynaptic effect can vary greatly. In sensory systems, inputs from "drivers" can be differentiated from those of "modulators." The driver can be identified as the transmitter of receptive field properties; the modulator can be identified as altering the probability of certain aspects of that transmission. Where receptive fields are not available, the distinction is more difficult and currently is undefined. We use the visual pathways, particularly the thalamic geniculate relay for which much relevant evidence is available, to explore ways in which drivers can be distinguished from modulators. The extent to which the distinction may apply first to other parts of the thalamus and then, possibly, to other parts of the brain is considered. We suggest the following distinctions: Cross-correlograms from driver inputs have sharper peaks than those from modulators; there are likely to be few drivers but many modulators for any one cell; and drivers are likely to act only through ionotropic receptors having a fast postsynaptic effect whereas modulators also are likely to activate metabotropic receptors having a slow and prolonged postsynaptic effect.

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    • "One potential advantage of functional data is the potential estimation of the directionality of connections via the use of effective connectivity (Friston, 1994). This could be crucial in delineating modulator and driver connections (Sherman and Guillery, 1998) and thereby linking neuroimaging with invasive studies (discussed in more detail below). Comparison with the results of DBS associated with specific thalamic nuclei may also be a way of achieving some degree of validation, assuming that variability in the location of nuclei could be one of the reasons for variability in the success of DBS across individual patients (Caparros-Lefebvre et al., 1999; Luttjohann and van Luijtelaar, 2013). "
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    ABSTRACT: Information flow between the thalamus and cerebral cortex is a crucial component of adaptive brain function, but the details of thalamocortical interactions in human subjects remain unclear. The principal aim of this study was to evaluate the agreement between functional thalamic network patterns, derived using seed-based connectivity analysis and independent component analysis (ICA) applied separately to resting state functional MRI (fMRI) data from 21 healthy participants. For the seed-based analysis, functional thalamic parcellation was achieved by computing functional connectivity (FC) between thalamic voxels and a set of pre-defined cortical regions. Thalamus-constrained ICA provided an alternative parcellation. Both FC analyses demonstrated plausible and comparable group-level thalamic subdivisions, in agreement with previous work. Quantitative assessment of the spatial overlap between FC thalamic segmentations, and comparison of each to a histological "gold-standard" thalamic atlas and a structurally-defined thalamic atlas, highlighted variations between them and, most notably, differences with both histological and structural results. Whilst deeper understanding of thalamocortical connectivity rests upon identification of features common to multiple non-invasive neuroimaging techniques (e.g. FC, structural connectivity and anatomical localisation of individual-specific nuclei), this work sheds further light on the functional organisation of the thalamus and the varying sensitivities of complementary analyses to resolve it. Copyright © 2015. Published by Elsevier Inc.
    Full-text · Article · Apr 2015 · NeuroImage
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    • "These large corticothalamic terminals tend to form complexes with the dendrites partially surrounded by astrocytic processes (Bartlett et al., 2000). Sherman and Guillery (1998) proposed the notion of " drivers " and " modulators " of thalamic neurons in the visual and somatosensory thalamus; this hypothesis has since been applied to the auditory system (Llano and Sherman, 2008). "
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    ABSTRACT: To follow an ever-changing auditory scene, the auditory brain is continuously creating a representation of the past to form expectations about the future. Unexpected events will produce an error in the predictions that should "trigger" the network's response. Indeed, neurons in the auditory midbrain, thalamus and cortex, respond to rarely occurring sounds while adapting to frequently repeated ones, i.e., they exhibit stimulus specific adaptation (SSA). SSA cannot be explained solely by intrinsic membrane properties, but likely involves the participation of the network. Thus, SSA is envisaged as a high order form of adaptation that requires the influence of cortical areas. However, present research supports the hypothesis that SSA, at least in its simplest form (i.e., to frequency deviants), can be transmitted in a bottom-up manner through the auditory pathway. Here, we briefly review the underlying neuroanatomy of the corticofugal projections before discussing state of the art studies which demonstrate that SSA present in the medial geniculate body (MGB) and inferior colliculus (IC) is not inherited from the cortex but can be modulated by the cortex via the corticofugal pathways. By modulating the gain of neurons in the thalamus and midbrain, the auditory cortex (AC) would refine SSA subcortically, preventing irrelevant information from reaching the cortex.
    Full-text · Article · Mar 2015 · Frontiers in Systems Neuroscience
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    • "These asymmetries are clearest in the first-order thalamic nuclei such as the Lateral Geniculate Nucleus (LGN), whose afferents can be separated into two classes – feedforward input from the retina and feedback from layer 6 of the first visual cortical area. These connections differ from each other in several ways: feedforward connections display strong initial EPSPs (excitatory postsynaptic potentials), use exclusively ionotropic Glutamate receptors, and have depressing synapses to paired pulse stimulation (Sherman and Guillery, 1998). Feedback connections terminate on the distal part of the dendritic arbour, evoke weaker EPSPs, are more modulatory in the sense that they employ both ionotropic and metabotropic synaptic components, and show paired-pulse facilitation (Sherman and Guillery, 2011). "
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    ABSTRACT: This paper reports a dynamic causal modelling study of electrocorticographic (ECoG) data that addresses functional asymmetries between forward and backward connections in the visual cortical hierarchy. Specifically, we ask whether forward connections employ gamma-band frequencies, while backward connections preferentially use lower (beta-band) frequencies. We addressed this question by modelling empirical cross spectra using a neural mass model equipped with superficial and deep pyramidal cell populations – that model the source of forward and backward connections respectively. This enabled us to reconstruct the transfer functions and associated spectra of specific subpopulations within cortical sources. We first established that Bayesian model comparison was able to discriminate between forward and backward connections; defined in terms of their cells of origin. We then confirmed that model selection was able to identify extrastriate (V4) sources as being hierarchically higher than early visual (V1) sources. Finally, an examination of the auto spectra and transfer functions associated with superficial and deep pyramidal cells confirmed that forward connections employed predominantly higher (gamma) frequencies, while backward connections were mediated by lower (alpha/beta) frequencies. We discuss these findings in relation to current views about alpha, beta, and gamma oscillations and predictive coding in the brain.
    Full-text · Article · Jan 2015 · NeuroImage
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