Interval Coding. II. Dendrite-Dependent Mechanisms

2007 ◽  
Vol 97 (4) ◽  
pp. 2744-2757 ◽  
Author(s):  
Brent Doiron ◽  
Anne-Marie M. Oswald ◽  
Leonard Maler
Keyword(s):  
Neural Coding ◽  
Pyramidal Neurons ◽  
Temporal Structure ◽  
Spike Trains ◽  
Sensory Cells ◽  
Cellular Mechanics ◽  
Dynamic Stimuli ◽  
Multiple Dimensions ◽  
Sensory Modalities ◽  
The Rich

The rich temporal structure of neural spike trains provides multiple dimensions to code dynamic stimuli. Popular examples are spike trains from sensory cells where bursts and isolated spikes can serve distinct coding roles. In contrast to analyses of neural coding, the cellular mechanics of burst mechanisms are typically elucidated from the neural response to static input. Bridging the mechanics of bursting with coding of dynamic stimuli is an important step in establishing theories of neural coding. Electrosensory lateral line lobe (ELL) pyramidal neurons respond to static inputs with a complex dendrite-dependent burst mechanism. Here we show that in response to dynamic broadband stimuli, these bursts lack some of the electrophysiological characteristics observed in response to static inputs. A simple leaky integrate-and-fire (LIF)-style model with a dendrite-dependent depolarizing afterpotential (DAP) is sufficient to match both the output statistics and coding performance of experimental spike trains. We use this model to investigate a simplification of interval coding where the burst interspike interval (ISI) codes for the scale of a canonical upstroke rather than a multidimensional stimulus feature. Using this stimulus reduction, we compute a quantization of the burst ISIs and the upstroke scale to show that the mutual information rate of the interval code is maximized at a moderate DAP amplitude. The combination of a reduced description of ELL pyramidal cell bursting and a simplification of the interval code increases the generality of ELL burst codes to other sensory modalities.

Songs to Syntax

2011 ◽  
Vol 5 (4) ◽  
pp. 22-32 ◽  
Author(s):  
Robert C. Berwick
Keyword(s):  
Auditory Perception ◽  
Convergent Evolution ◽  
Vocal Learning ◽  
Brain Regions ◽  
Auditory Memory ◽  
Central Component ◽  
Common Descent ◽  
Sensory Modalities ◽  
The Rich ◽  
The Brain

Language comprises a central component of a complex that is sometimes called “the human capacity.” This complex seems to have crystallized fairly recently among a small group in East Africa of whom people are all descendants. Common descent has been important in the evolution of the brain, such that avian and mammalian brains may be largely homologous, particularly in the case of brain regions involved in auditory perception, vocalization and auditory memory. There has been convergent evolution of the capacity for auditory-vocal learning, and possibly for structuring of external vocalizations, such that apes lack the abilities that are shared between songbirds and humans. Language’s recent evolutionary origin suggests that the computational machinery underlying syntax arose via the introduction of a single, simple, combinatorial operation. Further, the relation of a simple combinatorial syntax to the sensory-motor and thought systems reveals language to be asymmetric in design: while it precisely matches the representations required for inner mental thought, acting as the “glue” that binds together other internal cognitive and sensory modalities, at the same time it poses computational difficulties for externalization, that is, parsing and speech or signed production. Despite this mismatch, language syntax leads directly to the rich cognitive array that marks us as a symbolic species.

scholarly journals The Role of Landscapes and Landmarks in Bee Navigation: A Review

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 342 ◽  
Author(s):  
Bahram Kheradmand ◽  
James C. Nieh
Keyword(s):  
Sensory Input ◽  
Future Research ◽  
Motivational State ◽  
Research Directions ◽  
Clear Cut ◽  
Sensory Modalities ◽  
Future Research Directions ◽  
The Rich

The ability of animals to explore landmarks in their environment is essential to their fitness. Landmarks are widely recognized to play a key role in navigation by providing information in multiple sensory modalities. However, what is a landmark? We propose that animals use a hierarchy of information based upon its utility and salience when an animal is in a given motivational state. Focusing on honeybees, we suggest that foragers choose landmarks based upon their relative uniqueness, conspicuousness, stability, and context. We also propose that it is useful to distinguish between landmarks that provide sensory input that changes (“near”) or does not change (“far”) as the receiver uses these landmarks to navigate. However, we recognize that this distinction occurs on a continuum and is not a clear-cut dichotomy. We review the rich literature on landmarks, focusing on recent studies that have illuminated our understanding of the kinds of information that bees use, how they use it, potential mechanisms, and future research directions.

scholarly journals Predicting spike timing in highly synchronous auditory neurons at different sound levels

2013 ◽  
Vol 110 (7) ◽  
pp. 1672-1688 ◽  
Author(s):  
Bertrand Fontaine ◽  
Victor Benichoux ◽  
Philip X. Joris ◽  
Romain Brette
Keyword(s):  
Temporal Structure ◽  
Spike Trains ◽  
Sound Level ◽  
Spike Timing ◽  
Spike Threshold ◽  
Integrate And Fire ◽  
Fire Models ◽  
Wide Range

A challenge for sensory systems is to encode natural signals that vary in amplitude by orders of magnitude. The spike trains of neurons in the auditory system must represent the fine temporal structure of sounds despite a tremendous variation in sound level in natural environments. It has been shown in vitro that the transformation from dynamic signals into precise spike trains can be accurately captured by simple integrate-and-fire models. In this work, we show that the in vivo responses of cochlear nucleus bushy cells to sounds across a wide range of levels can be precisely predicted by deterministic integrate-and-fire models with adaptive spike threshold. Our model can predict both the spike timings and the firing rate in response to novel sounds, across a large input level range. A noisy version of the model accounts for the statistical structure of spike trains, including the reliability and temporal precision of responses. Spike threshold adaptation was critical to ensure that predictions remain accurate at different levels. These results confirm that simple integrate-and-fire models provide an accurate phenomenological account of spike train statistics and emphasize the functional relevance of spike threshold adaptation.

Temporally Irregular Mnemonic Persistent Activity in Prefrontal Neurons of Monkeys During a Delayed Response Task

2003 ◽  
Vol 90 (5) ◽  
pp. 3441-3454 ◽  
Author(s):  
Albert Compte, ◽  
Christos Constantinidis ◽  
Jesper Tegnér ◽  
Sridhar Raghavachari ◽  
Matthew V. Chafee ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Power Spectrum ◽  
Spike Train ◽  
Temporal Structure ◽  
Spike Trains ◽  
Delay Period ◽  
Delayed Response ◽  
Persistent Activity ◽  
Response Task ◽  
Delayed Response Task

An important question in neuroscience is whether and how temporal patterns and fluctuations in neuronal spike trains contribute to information processing in the cortex. We have addressed this issue in the memory-related circuits of the prefrontal cortex by analyzing spike trains from a database of 229 neurons recorded in the dorsolateral prefrontal cortex of 4 macaque monkeys during the performance of an oculomotor delayed-response task. For each task epoch, we have estimated their power spectrum together with interspike interval histograms and autocorrelograms. We find that 1) the properties of most (about 60%) neurons approximated the characteristics of a Poisson process. For about 25% of cells, with characteristics typical of interneurons, the power spectrum showed a trough at low frequencies (<20 Hz) and the autocorrelogram a dip near zero time lag. About 15% of neurons had a peak at <20 Hz in the power spectrum, associated with the burstiness of the spike train; 2) a small but significant task dependency of spike-train temporal structure: delay responses to preferred locations were characterized not only by elevated firing, but also by suppressed power at low (<20 Hz) frequencies; and 3) the variability of interspike intervals is typically higher during the mnemonic delay period than during the fixation period, regardless of the remembered cue. The high irregularity of neural persistent activity during the delay period is likely to be a characteristic signature of recurrent prefrontal network dynamics underlying working memory.

scholarly journals A critical exploration of “access” in qualitative international business field research

2016 ◽  
Vol 11 (2) ◽  
pp. 110-126 ◽  
Author(s):  
Daniella Fjellström ◽  
David S. A. Guttormsen
Keyword(s):  
International Business ◽  
Field Experiences ◽  
Field Research ◽  
Research Experiences ◽  
Content Type ◽  
Multiple Dimensions ◽  
Research Programmes ◽  
The Rich ◽  
Multicultural Research ◽  
Depth Interviews

Purpose – Researchers often face challenges in locating and obtaining relevant and meaningful information during qualitative international business (IB) field research in other countries. This process constitutes an immensely critical phase, which determines the success or failure of the research endeavour. The purpose of this paper is to discuss “access” as a multidimensional and contestable concept that poses particular challenges in international and multicultural research contexts. Design/methodology/approach – This paper builds on the experience as field researchers in China/Hong Kong (120 in-depth interviews) and the need to disseminate acquired field experiences, in particular concerning “access”. The multifaceted issue of “access” is rarely featured on the IB methodological agenda, and has become a silent feature of qualitative IB research. Findings – This paper is devoted to this nexus: the lack of focus on “access” issues, and the rich sources of acquired, but mostly veiled, field experiences that feature in both IB and management research programmes. A plausible explanation for this circumstance relates to the influence of mainstream positivist and objectivist paradigms in which researchers are not recognised as having an impact on research processes, hence taking this silent feature for granted. Originality/value – By viewing the multiple dimensions of “access”, we move beyond the mainstream understanding that merely relates it to the question of gaining access to a physical site and/or the time of an individual, and in which “access” is only an enterprise of securing pre-existing, tangible information. Drawing upon specific international field research experiences, this paper contributes to the methodological debate concerning “access” – beyond “technicality” and towards a concept of socio-cultural and multidimensional research practice.

scholarly journals Temporally precise control of single-neuron spiking by juxtacellular nanostimulation

2017 ◽  
Vol 117 (3) ◽  
pp. 1363-1378 ◽  
Author(s):  
Maik C. Stüttgen ◽  
Lourens J. P. Nonkes ◽  
H. Rüdiger A. P. Geis ◽  
Paul H. Tiesinga ◽  
Arthur R. Houweling
Keyword(s):  
Short Duration ◽  
Cortical Neurons ◽  
Action Potentials ◽  
Neural Coding ◽  
Spike Trains ◽  
Precise Control ◽  
Neuronal Spike Trains ◽  
The Impact ◽  
Activity Dependent

Temporal patterns of action potentials influence a variety of activity-dependent intra- and intercellular processes and play an important role in theories of neural coding. Elucidating the mechanisms underlying these phenomena requires imposing spike trains with precisely defined patterns, but this has been challenging due to the limitations of existing stimulation techniques. Here we present a new nanostimulation method providing control over the action potential output of individual cortical neurons. Spikes are elicited through the juxtacellular application of short-duration fluctuating currents (“kurzpulses”), allowing for the sub-millisecond precise and reproducible induction of arbitrary patterns of action potentials at all physiologically relevant firing frequencies (<120 Hz), including minute-long spike trains recorded in freely moving animals. We systematically compared our method to whole cell current injection, as well as optogenetic stimulation, and show that nanostimulation performance compares favorably with these techniques. This new nanostimulation approach is easily applied, can be readily performed in awake behaving animals, and thus promises to be a powerful tool for systematic investigations into the temporal elements of neural codes, as well as the mechanisms underlying a wide variety of activity-dependent cellular processes. NEW & NOTEWORTHY Assessing the impact of temporal features of neuronal spike trains requires imposing arbitrary patterns of spiking on individual neurons during behavior, but this has been difficult to achieve due to limitations of existing stimulation methods. We present a technique that overcomes these limitations by using carefully designed short-duration fluctuating juxtacellular current injections, which allow for the precise and reliable evocation of arbitrary patterns of neuronal spikes in single neurons in vivo.

scholarly journals Broad frequency sensitivity and complex neural coding in the larval zebrafish auditory system

2020 ◽  
Author(s):  
Rebecca E. Poulsen ◽  
Leandro A. Sholz ◽  
Lena Constantin ◽  
Itia Favre-Bulle ◽  
Gilles C. Vanwalleghem ◽  
...  
Keyword(s):  
Auditory System ◽  
Neural Coding ◽  
Larval Fish ◽  
Temporal Structure ◽  
Frequency Discrimination ◽  
Single Frequency ◽  
Auditory Stimuli ◽  
Functional Clustering ◽  
Zebrafish Larvae ◽  
Auditory Systems

SUMMARYMost animals have complex auditory systems that identify salient features of the acoustic landscape to direct appropriate responses. In fish, these features include the volume, frequency, complexity, and temporal structure of auditory stimuli transmitted through water. Larval fish have simple brains compared to adults, but swim freely and depend on sophisticated sensory processing for survival. Zebrafish larvae, an important model for studying brain-wide neural networks, have thus far been found to possess a rudimentary auditory system, sensitive to a narrow range of frequencies and without evident sensitivity to auditory features that are salient and ethologically important to adult fish. Here, we have combined a novel method for delivering water-borne sounds, a diverse assembly of acoustic stimuli, and whole-brain calcium imaging to describe the responses of individual auditory neurons across the brains of zebrafish larvae. Our results reveal responses to frequencies ranging from 100Hz to 4kHz, with evidence of frequency discrimination from 100Hz to 2.5kHz. Frequency-selective neurons are located in numerous regions of the brain, and neurons responsive to the same frequency are spatially grouped in some regions. Using functional clustering, we identified categories of neurons that are selective for pure tones of a single frequency, white noise, the sharp onset of auditory stimuli, and stimuli involving a gradual crescendo. These results suggest a more nuanced auditory system than has previously been described in larval fish and provide insights into how a young animal’s auditory system can both function acutely and serve as the scaffold of a more complex adult system.

scholarly journals An uncertainty principle for neural coding: Conjugate representations of position and velocity are mapped onto firing rates and co-firing rates of neural spike trains

2019 ◽  
Author(s):  
Ryan Grgurich ◽  
Hugh T. Blair
Keyword(s):  
Firing Rate ◽  
Uncertainty Principle ◽  
Neural Coding ◽  
Spike Trains ◽  
Grid Cells ◽  
Rate Code ◽  
Biologically Inspired ◽  
Firing Rates ◽  
Neural Populations ◽  
Similar Information

AbstractThe hippocampal system contains neural populations that encode an animal’s position and velocity as it navigates through space. Here, we show that such populations can embed two codes within their spike trains: a firing rate code (R) conveyed by within-cell spike intervals, and a co-firing rate code (Ṙ) conveyed by between-cell spike intervals. These two codes behave as conjugates of one another, obeying an analog of the uncertainty principle from physics: information conveyed in R comes at the expense of information in Ṙ, and vice versa. An exception to this trade-off occurs when spike trains encode a pair of conjugate variables, such as position and velocity, which do not compete for capacity across R and Ṙ. To illustrate this, we describe two biologically inspired methods for decoding R and Ṙ, referred to as sigma and sigma-chi decoding, respectively. Simulations of head direction (HD) and grid cells show that if firing rates are tuned for position (but not velocity), then position is recovered by sigma decoding, whereas velocity is recovered by sigma-chi decoding. Conversely, simulations of oscillatory interference among theta-modulated “speed cells” show that if co-firing rates are tuned for position (but not velocity), then position is recovered by sigma-chi decoding, whereas velocity is recovered by sigma decoding. Between these two extremes, information about both variables can be distributed across both channels, and partially recovered by both decoders. These results suggest that neurons with different spatial and temporal tuning properties—such as speed versus grid cells—might not encode different information, but rather, distribute similar information about position and velocity in different ways across R and Ṙ. Such conjugate coding of position and velocity may influence how hippocampal populations are interconnected to form functional circuits, and how biological neurons integrate their inputs to decode information from firing rates and spike correlations.

Muscarinic Inhibition of Persistent Na+ Current in Rat Neocortical Pyramidal Neurons

1998 ◽  
Vol 79 (3) ◽  
pp. 1579-1582 ◽  
Author(s):  
Thomas Mittmann ◽  
Christian Alzheimer
Keyword(s):  
Pyramidal Neurons ◽  
Pyramidal Cells ◽  
Cholinergic Innervation ◽  
Voltage Range ◽  
Rat Neocortex ◽  
The Rich ◽  
Subthreshold Voltage ◽  
Whole Cell Recordings ◽  
Muscarinic Modulation ◽  
Neocortical Pyramidal Neurons

Mittmann, Thomas and Christian Alzheimer. Muscarinic inhibition of persistent Na+ current in rat neocortical pyramidal neurons. J. Neurophysiol. 79: 1579–1582, 1998. Muscarinic modulation of persistent Na+ current ( I NaP) was studied using whole cell recordings from acutely isolated pyramidal cells of rat neocortex. After suppression of Ca2+ and K+ currents, I NaP was evoked by slow depolarizing voltage ramps or by long depolarizing voltage steps. The cholinergic agonist, carbachol, produced an atropine-sensitive decrease of I NaP at all potentials. When applied at a saturating concentration (20 μM), carbachol reduced peak I NaP by 38% on average. Carbachol did not alter the voltage dependence of I NaP activation nor did it interfere with the slow inactivation of I NaP. Our data indicate that I NaP can be targeted by the rich cholinergic innervation of the neocortex. Because I NaP is activated in the subthreshold voltage range, cholinergic inhibition of this current would be particularly suited to modulate the electrical behavior of neocortical pyramidal cells below and near firing threshold.

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