Dendritic spikes enhance stimulus selectivity in cortical neurons in vivo

Smith, Spencer L.; Smith, Ikuko T.; Branco, Tiago; Häusser, Michael

doi:10.1038/nature12600

Cited by 388 publications

(453 citation statements)

References 39 publications

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“…4g, h). These results suggest that local connections contribute to the stimulus selectivity of L2/3 neurons by providing tuned excitation that modulates the membrane potential in a manner qualitatively similar to that observed in vivo [19][20][21][22][23] .…”

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confidence: 56%

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Functional organization of excitatory synaptic strength in primary visual cortex

Cossell

Iacaruso

Muir

et al. 2015

Nature

519

670

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The strength of synaptic connections fundamentally determines how neurons influence each other's firing. Excitatory connection amplitudes between pairs of cortical neurons vary over two orders of magnitude, comprising only very few strong connections among many weaker ones [1][2][3][4][5][6][7][8][9] . Although this highly skewed distribution of connection strengths is observed in diverse cortical areas 1-9 , its functional significance remains unknown: it is not clear how connection strength relates to neuronal response properties, nor how strong and weak inputs contribute to information processing in local microcircuits. Here we reveal that the strength of connections between layer 2/3 (L2/3) pyramidal neurons in mouse primary visual cortex (V1) obeys a simple rule-the few strong connections occur between neurons with most correlated responses, while only weak connections link neurons with uncorrelated responses. Moreover, we show that strong and reciprocal connections occur between cells with similar spatial receptive field structure. Although weak connections far outnumber strong connections, each neuron receives the majority of its local excitation from a small number of strong inputs provided by the few neurons with similar responses to visual features. By dominating recurrent excitation, these infrequent yet powerful inputs disproportionately contribute to feature preference and selectivity. Therefore, our results show that the apparently complex organization of excitatory connection strength reflects the Reprints and permissions information is available at www.nature.com/reprints.

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confidence: 56%

“…In mouse V1, a simple cell's subthreshold response to drifting grating stimuli [19][20][21][22][23] is characterized by two components that are determined by the angle and phase of the grating in relation to its RF (Fig. 4a).…”

mentioning

confidence: 99%

Functional organization of excitatory synaptic strength in primary visual cortex

Cossell

Iacaruso

Muir

et al. 2015

Nature

519

670

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“…First, weak spatial inputs may be sufficient for place-cell formation. Sharply confined firing fields may be generated by local mechanisms in the hippocampal network, such as recurrent inhibition (de Almeida et al 2009;Monaco and Abbott 2011), Hebbian plasticity (Rolls et al 2006;Savelli and Knierim 2010), or active dendritic properties (Smith et al 2013). Alternatively, place cells may be generated from other classes of spatially modulated cells, such as border cells, which have adult-like properties from the very first day of exploration outside the nest (Bjerknes et al 2014).…”

Section: Upstream Of Place Cells: Grid Cells and Other Cell Typesmentioning

confidence: 99%

Place Cells, Grid Cells, and Memory

Moser

Rowland

Moser

2015

Cold Spring Harb Perspect Biol

421

267

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The hippocampal system is critical for storage and retrieval of declarative memories, including memories for locations and events that take place at those locations. Spatial memories place high demands on capacity. Memories must be distinct to be recalled without interference and encoding must be fast. Recent studies have indicated that hippocampal networks allow for fast storage of large quantities of uncorrelated spatial information. The aim of the this article is to review and discuss some of this work, taking as a starting point the discovery of multiple functionally specialized cell types of the hippocampal-entorhinal circuit, such as place, grid, and border cells. We will show that grid cells provide the hippocampus with a metric, as well as a putative mechanism for decorrelation of representations, that the formation of environment-specific place maps depends on mechanisms for long-term plasticity in the hippocampus, and that long-term spatiotemporal memory storage may depend on offline consolidation processes related to sharp-wave ripple activity in the hippocampus. The multitude of representations generated through interactions between a variety of functionally specialized cell types in the entorhinal-hippocampal circuit may be at the heart of the mechanism for declarative memory formation.T he scientific study of human memory started with Herman Ebbinghaus, who initiated the quantitative investigation of associative memory processes as they take place (Ebbinghaus 1885). Ebbinghaus described the conditions that influence memory formation and he determined several basic principles of encoding and recall, such as the law of frequency and the effect of time on forgetting. With Ebbinghaus, higher mental functions were brought to the laboratory. In parallel with the human learning tradition that Ebbinghaus started, a new generation of experimental psychologists described the laws of associative learning in animals. With behaviorists like Pavlov, Watson, Hull, Skinner, and Tolman, a rigorous program for identifying the laws of animal learning was initiated. By the middle of the 20th century, a language for associative learning processes had been developed, and many of the fundamental relationships between environment and behavior had been described. What was completely missing, though, was an understanding of the neural activity underlying the formation of the memory. The behaviorists had deliberately shied away from physiological explanations because of the intangible nature of neural activity at that time.Then the climate began to change. Karl Lashley had shown that lesions in the cerebral cortex had predictable effects on behavior in Editors: Eric R. Kandel, Yadin Dudai, and Mark R. Mayford Additional Perspectives on Learning and Memory available at

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“…[36][37][38] These calcium potentials carry incoming signals actively along the dendrite toward the cell body. Moreover, both in vitro and in vivo studies suggest that information impinging upon the peripheral dendritic branches is carried toward the mentioned calcium spike [39][40][41][42] Thus, there is an active, two-stage signaling process along the apical dendrites of pyramidal neurons: first, input to the distal tuft dendrites is carried toward the main dendrite by means of NMDA spikes; second, calcium potentials triggered close to the main bifurcation relay the signals to the soma ( fig. 2B).…”

Section: The Effects Of General Anesthetics On Apical Dendrites Of Pymentioning

confidence: 99%

The Role of Dendritic Signaling in the Anesthetic Suppression of Consciousness

Meyer

2015

Anesthesiology

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Despite considerable progress in the identification of the molecular targets of general anesthetics, it remains unclear how these drugs affect the brain at the systems level to suppress consciousness. According to recent proposals, anesthetics may achieve this feat by interfering with corticocortical topdown processes, that is, by interrupting information flow from association to early sensory cortices. Such a view entails two immediate questions. First, at which anatomical site, and by virtue of which physiological mechanism, do anesthetics interfere with top-down signals? Second, why does a breakdown of top-down signaling cause unconsciousness? While an answer to the first question can be gleaned from emerging neurophysiological evidence on dendritic signaling in cortical pyramidal neurons, a response to the second is offered by increasingly popular theoretical frameworks that place the element of prediction at the heart of conscious perception. Science magazine posed this question in a special section titled "What don't we know?," dedicated to the greatest challenges of contemporary science. 1 "Scientists are chipping away at the drugs' effects on individual neurons," the article reads, "but understanding how they render us unconscious will be a tougher nut to crack." This prediction proved correct: a decade later, we have expanded considerably our knowledge of the molecular targets of general anesthetics, but it remains enigmatic how these drugs affect the brain at the systems level. Why does the potentiation of γ-aminobutyric acid (GABA) receptors caused by propofol or desflurane cause unconsciousness? How are the brain's computational processes affected by this and other molecular mechanisms of anesthetics, so that patients undergoing surgery cease to experience their surrounds in terms of sight, sound, and touch? Anesthesiologists and cognitive neuroscientists alike have been captivated by these questions and have proposed a number of models in an attempt to answer them, such as Flohr's "information processing theory of anesthesia," 2 Alkire's "thalamic consciousness switch hypothesis," 3-6 Mashour's "cognitive unbinding paradigm," 7,8 John and Prichep's "anesthetic cascade," 9 or Hudetz's "forgotten present." 10,11 We shall return to some of these frameworks in a later section of the article.One recent development is particularly intriguing. Given that the most striking feature of general anesthesia is an interruption of the patient's ability to perceive the environment, it would appear intuitive for anesthetics to interfere primarily with bottom-up information flow along the sensory pathways, that is, with the signals that carry perceptual information from the thalamus to the primary sensory cortices and on to unimodal and multimodal association cortices. However, the very opposite appears to be the case. Several recent studies-carried out in both humans and animals, and using a variety of different anesthetic agents-have investigated differences in directional corticocortical connectivity bet...

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Dendritic spikes enhance stimulus selectivity in cortical neurons in vivo

Cited by 388 publications

References 39 publications

Functional organization of excitatory synaptic strength in primary visual cortex

Functional organization of excitatory synaptic strength in primary visual cortex

Place Cells, Grid Cells, and Memory

The Role of Dendritic Signaling in the Anesthetic Suppression of Consciousness

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