scholarly journals Where’s the Noise? Key Features of Spontaneous Activity and Neural Variability Arise through Learning in a Deterministic Network

2015 ◽  
Vol 11 (12) ◽  
pp. e1004640 ◽  
Author(s):  
Christoph Hartmann ◽  
Andreea Lazar ◽  
Bernhard Nessler ◽  
Jochen Triesch
Keyword(s):  
Spontaneous Activity ◽  
Key Features ◽  
Neural Variability

scholarly journals Where’s the noise? Key features of neuronal variability and inference emerge from self-organized learning

2014 ◽  
Author(s):  
Christoph Hartmann ◽  
Andreea Lazar ◽  
Jochen Triesch
Keyword(s):  
Spontaneous Activity ◽  
Network Model ◽  
Neural Circuit ◽  
Intrinsic Noise ◽  
Spike Timing ◽  
Homeostatic Plasticity ◽  
Neural Recordings ◽  
Self Organized ◽  
Key Features ◽  
Neural Variability

AbstractTrial-to-trial variability and spontaneous activity of cortical recordings have been suggested to reflect intrinsic noise. This view is currently challenged by mounting evidence for structure in these phenomena: Trial-to-trial variability decreases following stimulus onset and can be predicted by previous spontaneous activity. This spontaneous activity is similar in magnitude and structure to evoked activity and can predict decisions. Allof the observed neuronal properties described above can be accounted for, at an abstract computational level, by the sampling-hypothesis, according to which response variability reflects stimulus uncertainty. However, a mechanistic explanation at the level of neural circuit dynamics is still missing.In this study, we demonstrate that all of these phenomena can be accounted for by a noise-free self-organizing recurrent neural network model (SORN). It combines spike-timing dependent plasticity (STDP) and homeostatic mechanisms in a deterministic network of excitatory and inhibitory McCulloch-Pitts neurons. The network self-organizes to spatio-temporally varying input sequences.We find that the key properties of neural variability mentioned above develop in this model as the network learns to perform sampling-like inference. Importantly, the model shows high trial-to-trial variability although it is fully deterministic. This suggests that the trial-to-trial variability in neural recordings may not reflect intrinsic noise. Rather, it may reflect a deterministic approximation of sampling-like learning and inference. The simplicity of the model suggests that these correlates of the sampling theory are canonical properties of recurrent networks that learn with a combination of STDP and homeostatic plasticity mechanisms.Author SummaryNeural recordings seem very noisy. If the exact same stimulus is shown to an animal multiple times, the neural response will vary. In fact, the activity of a single neuron shows many features of a stochastic process. Furthermore, in the absence of a sensory stimulus, cortical spontaneous activity has a magnitude comparable to the activity observed during stimulus presentation. These findings have led to a widespread belief that neural activity is indeed very noisy. However, recent evidence indicates that individual neurons can operate very reliably and that the spontaneous activity in the brain is highly structured, suggesting that much of the noise may in fact be signal. One hypothesis regarding this putative signal is that it reflects a form of probabilistic inference through sampling. Here we show that the key features of neural variability can be accounted for in a completely deterministic network model through self-organization. As the network learns a model of its sensory inputs, the deterministic dynamics give rise to sampling-like inference. Our findings show that the notorious variability in neural recordings does not need to be seen as evidence for a noisy brain. Instead it may reflect sampling-like inference emerging from a self-organized learning process.

Riemann–Weyl in Deleuze's Bergsonism and the Constitution of the Contemporary Physico-Mathematical Space

2015 ◽  
Vol 9 (1) ◽  
pp. 59-87 ◽  
Author(s):  
Martin Calamari
Keyword(s):  
Field Theory ◽  
Gauge Field ◽  
Fibre Bundle ◽  
History Of Mathematics ◽  
Gauge Field Theory ◽  
Contemporary Science ◽  
Explicit Mention ◽  
History Of ◽  
Key Features ◽  
Bernhard Riemann

In recent years, the ideas of the mathematician Bernhard Riemann (1826–66) have come to the fore as one of Deleuze's principal sources of inspiration in regard to his engagements with mathematics, and the history of mathematics. Nevertheless, some relevant aspects and implications of Deleuze's philosophical reception and appropriation of Riemann's thought remain unexplored. In the first part of the paper I will begin by reconsidering the first explicit mention of Riemann in Deleuze's work, namely, in the second chapter of Bergsonism (1966). In this context, as I intend to show first, Deleuze's synthesis of some key features of the Riemannian theory of multiplicities (manifolds) is entirely dependent, both textually and conceptually, on his reading of another prominent figure in the history of mathematics: Hermann Weyl (1885–1955). This aspect has been largely underestimated, if not entirely neglected. However, as I attempt to bring out in the second part of the paper, reframing the understanding of Deleuze's philosophical engagement with Riemann's mathematics through the Riemann–Weyl conjunction can allow us to disclose some unexplored aspects of Deleuze's further elaboration of his theory of multiplicities (rhizomatic multiplicities, smooth spaces) and profound confrontation with contemporary science (fibre bundle topology and gauge field theory). This finally permits delineation of a correlation between Deleuze's plane of immanence and the contemporary physico-mathematical space of fundamental interactions.

Katherine Mansfield and Translation

2015 ◽  
Keyword(s):  
Twentieth Century ◽  
Central Place ◽  
Literary Texts ◽  
Katherine Mansfield ◽  
Literary Language ◽  
Specific Interest ◽  
Literary Traditions ◽  
Political Ideas ◽  
Key Features ◽  
Critical Interest

Our understanding of Anglophone modernism has been transformed by recent critical interest in translation. The central place of translation in the circulation of aesthetic and political ideas in the early twentieth century has been underlined, for example, as well as translation’s place in the creative and poetic dynamics of key modernist texts. This volume of Katherine Mansfield Studies offers a timely assessment of Mansfield’s place in such exchanges. As a reviewer, she developed a specific interest in literatures in translation, as well as showing a keen awareness of the translator’s presence in the text. Throughout her life, Mansfield engaged with new literary texts through translation, either translating proficiently herself, or working alongside a co-translator to explore the semantic and stylistic challenges of partially known languages. The metaphorical resonances of translating, transition and marginality also remain key features of her writing throughout her life. Meanwhile, her enduring popularity abroad is ensured by translations of her works, all of which reveal sociological and even ideological agendas of their own, an inevitable reflection of individual translators’ readings of her works, and the literary traditions of the new country and language of reception. The contributions to this volume refine and extend our appreciation of her specifically trans-linguistic and trans-literary lives. They illuminate the specific and more general influences of translation on Mansfield’s evolving technique and, jointly, they reveal the importance of translation on her literary language, as well as for her own particular brand of modernism.

Maclaurin on Occasionalism: A Reply to Ablondi

2016 ◽  
Vol 14 (1) ◽  
pp. 125-135
Author(s):  
Patrick J. Connolly
Keyword(s):  
Eighteenth Century ◽  
Recent Article ◽  
Gravitational Attraction ◽  
Matter Theory ◽  
Key Features ◽  
Short Essay ◽  
The Way

In a recent article Fred Ablondi compares the different approaches to occasionalism put forward by two eighteenth-century Newtonians, Colin Maclaurin and Andrew Baxter. The goal of this short essay is to respond to Ablondi by clarifying some key features of Maclaurin's views on occasionalism and the cause of gravitational attraction. In particular, I explore Maclaurin's matter theory, his views on the explanatory limits of mechanism, and his appeals to the authority of Newton. This leads to a clearer picture of the way in which Maclaurin understood gravitational attraction and the workings of nature.

Unbiased Stereological Quantification of Key Features of Diabetic Nephropathy

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 516-P
Author(s):  
TANJA X. PEDERSEN ◽  
THEA T. JOHANSEN ◽  
LISBETH N. FINK ◽  
NIELS VRANG ◽  
THOMAS SECHER
Keyword(s):  
Diabetic Nephropathy ◽  
Key Features
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