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How REM sleep shapes hypothalamic computations for feeding behavior

TRENDS IN NEUROSCIENCES 2021年第12期44卷 990-1003页

作者： Oesch, Lukas T. Adamantidis, Antoine R. Univ Hosp Bern Inselspital Dept Neurol Zentrum Experimentelle Neurol Bern Switzerland Univ Bern Dept Biomed Res Bern Switzerland Univ Calif Los Angeles Dept Neurobiol Los Angeles CA USA

The electrical activity of diverse brain cells is modulated across states of vigilance, namely wakefulness, non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep. Enhanced activity of neuronal circuits during NREM sleep impacts on subsequent awake behaviors, yet the significance of their activation, or lack thereof, during REM sleep remains unclear. This review focuses on feeding-promoting cells in the lateral hypothalamus (LH) that express the vesicular GABA and glycine transporter (vgat) as a model to further understand the impact of REM sleep on neural encoding of goal-directed behavior. It emphasizes both spatial and temporal aspects of hypothalamic cell dynamics across awake behaviors and REM sleep, and discusses a role for REM sleep in brain plasticity underlying energy homeostasis and behavioral optimization.

关键词： sleep feeding goal-directed behavior hypothalamus population coding

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Weighting neurons by selectivity produces near-optimal population codes

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JOURNAL OF NEUROPHYSIOLOGY 2019年第5期121卷 1924-1937页

作者： Zavitz, Elizabeth Price, Nicholas S. C. Monash Univ Dept Physiol 26 Innovat Walk Clayton Vic 3800 Australia Monash Univ Biomed Discovery Inst Clayton Vic Australia Monash Univ Australian Res Council Ctr Excellence Integrat Brain Funct Clayton Vic Australia

Perception is produced by "reading out" the representation of a sensory stimulus contained in the activity of a population of neurons. To examine experimentally how populations code information, a common approach is to decode a linearly weighted sum of the neurons' spike counts. This approach is popular because of the biological plausibility of weighted, nonlinear integration. For neurons recorded in vivo, weights are highly variable when derived through optimization methods, but it is unclear how the variability affects decoding performance in practice. To address this, we recorded from neurons in the middle temporal area (MT) of anesthetized marmosets (Callithrix jacchus) viewing stimuli comprising a sheet of dots that moved coherently in 1 of 12 different directions. We found that high peak response and direction selectivity both predicted that a neuron would be weighted more highly in an optimized decoding model. Although learned weights differed markedly from weights chosen according to a priori rules based on a neuron's tuning profile, decoding performance was only marginally better for the learned weights. In the models with a priori rules, selectivity is the best predictor of weighting, and defining weights according to a neuron's preferred direction and selectivity improves decoding performance to very near the maximum level possible, as defined by the learned weights. NEW & NOTEWORTHY We examined which aspects of a neuron's tuning account for its contribution to sensory coding. Strongly direction-selective neurons are weighted most highly by optimal decoders trained to discriminate motion direction. Models with predefined decoding weights demonstrate that this weighting scheme causally improved direction representation by a neuronal population. Optimizing decoders (using a generalized linear model or Fisher's linear discriminant) led to only marginally better performance than decoders based purely on a neuron's preferred direction and selectivity.

关键词： decoding direction marmoset MT population coding visual motion

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Local and Global Correlations between Neurons in the Middle Temporal Area of Primate Visual Cortex

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CEREBRAL CORTEX 2015年第9期25卷 3182-3196页

作者： Solomon, Selina S. Chen, Spencer C. Morley, John W. Solomon, Samuel G. ARC Ctr Excellence Vis Sci Sydney NSW Australia Univ Sydney Sch Med Sci Discipline Physiol Sydney NSW 2006 Australia Univ Sydney Bosch Inst Sydney NSW 2006 Australia Univ Western Sydney Sch Med Campbelltown NSW 2560 Australia UCL Dept Expt Psychol London WC1P 0AH England

In humans and other primates, the analysis of visual motion includes populations of neurons in the middle-temporal (MT) area of visual cortex. Motion analysis will be constrained by the structure of neural correlations in these populations. Here, we use multi-electrode arrays to measure correlations in anesthetized marmoset, a New World monkey where area MT lies exposed on the cortical surface. We measured correlations in the spike count between pairs of neurons and within populations of neurons, for moving dot fields and moving gratings. Correlations were weaker in area MT than in area V1. The magnitude of correlations in area MT diminished with distance between receptive fields, and difference in preferred direction. Correlations during presentation of moving gratings were stronger than those during presentation of moving dot fields, extended further across cortex, and were less dependent on the functional properties of neurons. Analysis of the timescales of correlation suggests presence of 2 mechanisms. A local mechanism, associated with near-synchronous spiking activity, is strongest in nearby neurons with similar direction preference and is independent of visual stimulus. A global mechanism, operating over larger spatial scales and longer timescales, is independent of direction preference and is modulated by the type of visual stimulus presented.

关键词： area MT extrastriate marmoset population coding visual motion

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Integrated neural dynamics for behavioural decisions and attentional competition in the prefrontal cortex

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EUROPEAN JOURNAL OF NEUROSCIENCE 2022年第4期56卷 4393-4410页

作者： Erez, Yaara Kadohisa, Mikiko Petrov, Philippe Sigala, Natasha Buckley, Mark J. Kusunoki, Makoto Duncan, John Bar Ilan Univ Fac Engn IL-5290002 Ramat Gan Israel Univ Cambridge MRC Cognit & Brain Sci Unit Cambridge England Bar Ilan Univ Gonda Multidisciplinary Brain Res Ctr Ramat Gan Israel Univ Oxford Dept Expt Psychol Oxford England Brighton & Sussex Med Sch Brighton E Sussex England Univ Sussex Sackler Ctr Consciousness Sci Brighton E Sussex England

In the behaving monkey, complex neural dynamics in the prefrontal cortex contribute to context-dependent decisions and attentional competition. We used demixed principal component analysis to track prefrontal activity dynamics in a cued target detection task. In this task, the animal combined identity of a visual object with a prior instruction cue to determine a target/nontarget decision. From population activity, we extracted principal components for each task feature and examined their time course and sensitivity to stimulus and task variations. For displays containing a single choice object in left or right hemifield, object identity, cue identity and decision were all encoded in population activity, with different dynamics and lateralisation. Object information peaked at 100-200 ms from display onset and was largely confined to the contralateral hemisphere. Cue information was weaker and present even prior to display onset. Integrating information from cue and object, decision information arose more slowly and was bilateral. Individual neurons contributed independently to coding of the three task features. The analysis was then extended to displays with a target in one hemifield and a competing distractor in the other. In this case, the data suggest that each hemisphere initially encoded the identity of the contralateral object. The distractor representation was then rapidly suppressed, with the final target decision again encoded bilaterally. The results show how information is coded along task-related dimensions while competition is resolved and suggest how information flows within and across frontal lobes to implement a learned behavioural decision.

关键词： attention cognitive control dimensionality reduction dynamics non-human primate population coding prefrontal cortex single units

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Effect of preceding stimulation on sound localization and its representation in the auditory midbrain

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EUROPEAN JOURNAL OF NEUROSCIENCE 2017年第3期45卷 460-471页

作者： Tolnai, Sandra Beutelmann, Rainer Klump, Georg M. Carl von Ossietzky Univ Oldenburg Sch Med & Hlth Sci Anim Physiol & Behav Grp Cluster Excellence Hearing4allDept Neurosci D-26111 Oldenburg Germany

Prior stimulation can influence the perception of sound source location. Some psychophysical sound localization procedures differ in the amount of prior stimulation, which may affect measures of localization accuracy. If and how particularly the number of preceding stimuli affects sound localization and the neural representation of sound source position has not been investigated so far and will be the focus of the present report. We trained Mongolian gerbils in a left/right discrimination task where the target stimulus was preceded by silence or followed a number of reference stimuli. Localization thresholds decreased with the number of references presented before the target stimulus. The smallest thresholds were found after the presentation of a train of 5 reference stimuli and after silence. We recorded from units in the inferior colliculus (IC) of anaesthetized gerbils using virtual-acoustic space stimuli mimicking the ones used in the behavioural task and applied signal detection theory to compare behavioural and neurometric thresholds. We found that neurometric thresholds based on spike rate information of single units covered a wide range of threshold values but only neurometric thresholds that were based on responses of small populations of IC units reached consistently thresholds we also observed in the behavioural experiment. Unlike behavioural thresholds, however, neurometric thresholds were independent of the number of reference stimuli suggesting that processing stages downstream from the IC might better reflect the effect of prior stimulation.

关键词： free-field sound localization Mongolian gerbil population coding signal detection theory

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Perceptual costs for motion transparency evaluated by two performance measures

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VISION RESEARCH 2009年第17期49卷 2217-2224页

作者： Suzuki, Naoto Watanabe, Osamu Muroran Inst Technol Dept Comp Sci & Syst Engn Muroran Hokkaido 0508585 Japan

Transparency perception is recognized as one of the important phenomena to understand the computational mechanism of early visual system. Transparency perception indicates that a simple theory reconstructing a single-valued field of a visual attribute, such as an optical-flow field, cannot model the neural mechanism for the human visual system and raises a fundamental issue of how visual attributes are represented and detected in the brain. It is considered that one of the important cues to reveal the neural encoding mechanism for overlapping surfaces is the perceptual cost in transparency perception. It has been known that the perceptual performance in motion transparency is worse than that expected from single motion perception. This perceptual "cost" would reflect the encoding strategy for transparent motions. Here we present a systematic study comparing the perceptual costs in motion transparency evaluated by two performance measures. The result showed that the properties of the perceptual costs varied with the performance measures. The perceptual cost evaluated by the motion detection threshold became smaller as a directional difference between overlapping motions increased, whereas the cost examined with the precision of directional judgments became worse. A computational analysis suggests that these contradictory results cannot be explained by a simple population coding model for motion directions. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Motion transparency Precision Threshold Perceptual cost population coding

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Encoding of Smooth-Pursuit Eye Movement Initiation by a population of Vermal Purkinje Cells

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CEREBRAL CORTEX 2012年第4期22卷 877-891页

作者： Dash, Suryadeep Catz, Nicolas Dicke, Peter W. Thier, Peter Univ Tubingen Dept Cognit Neurol Hertie Inst Clin Brain Res D-72076 Tubingen Germany

Lesion studies suggest that the oculomotor vermis (OMV) is critical for the initiation of smooth-pursuit eye movements (SPEMs);yet, its specific role has remained elusive. In this study, we tested the hypothesis that vermal Purkinje cells (PCs) may be needed to fine-tune the kinematic description of SPEM initiation. Recording from identified PCs from the monkey OMV, we observed that SPEM-related PCs were characterized by a formidable diversity of response profiles with typically only modest reflection of eye movement kinematics. In contrast, the PC population discharge could be perfectly predicted based on a linear combination of eye acceleration, velocity, and position. This finding is in full accord with a role of the OMV in shaping eye movement kinematics. It, moreover, supports the notion that this shaping action is based on a population code, whose anatomic basis is the convergence of PCs on target neurons in the cerebellar nuclei.

关键词： cerebellum eye movements macaque population coding pursuit

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DISTRIBUTED SPATIAL coding IN THE SUPERIOR COLLICULUS - A REVIEW

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VISUAL NEUROSCIENCE 1991年第1期6卷 3-13页

作者： MCILWAIN, JT [a1 ]Division of Biology and Medicine Brown University Providence

This paper reviews evidence that the superior colliculus (SC) of the midbrain represents visual direction and certain aspects of saccadic eye movements in the distribution of activity across a population of cells. Accurate and precise eye movements appear to be mediated, in part at least, by cells of the SC that have large sensory receptive fields and/or discharge in association with a range of saccades. This implies that visual points or saccade targets are represented by patches rather than points of activity in the SC. Perturbation of the pattern of collicular discharge by focal inactivation modifies saccade amplitude and direction in a way consistent with distributed coding. Several models have been advanced to explain how such a code might be implemented in the colliculus. Evidence related to these hypotheses is examined and continuing uncertainties are identified.

关键词： SUPERIOR COLLICULUS SACCADE DISTRIBUTED coding ENSEMBLE coding population coding

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Separability of stimulus parameter encoding by on-off directionally selective rabbit retinal ganglion cells

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JOURNAL OF NEUROPHYSIOLOGY 2011年第5期105卷 2083-2099页

作者： Nowak, Przemyslaw Dobbins, Allan C. Gawne, Timothy J. Grzywacz, Norberto M. Amthor, Franklin R. Univ Alabama Birmingham Dept Psychol Birmingham AL 35294 USA Univ Alabama Birmingham Dept Vis Sci Birmingham AL 35294 USA Univ Alabama Birmingham Dept Biomed Engn Birmingham AL 35294 USA Univ So Calif Dept Biomed Engn Los Angeles CA 90089 USA

Nowak P, Dobbins AC, Gawne TJ, Grzywacz NM, Amthor FR. Separability of stimulus parameter encoding by on-off directionally selective rabbit retinal ganglion cells. J Neurophysiol 105: 2083-2099, 2011. First published February 16, 2011;doi:10.1152/jn.00941.2010.-The ganglion cell output of the retina constitutes a bottleneck in sensory processing in that ganglion cells must encode multiple stimulus parameters in their responses. Here we investigate encoding strategies of On-Off directionally selective retinal ganglion cells (On-Off DS RGCs) in rabbits, a class of cells dedicated to representing motion. The exquisite axial discrimination of these cells to preferred vs. null direction motion is well documented: it is invariant with respect to speed, contrast, spatial configuration, spatial frequency, and motion extent. However, these cells have broad direction tuning curves and their responses also vary as a function of other parameters such as speed and contrast. In this study, we examined whether the variation in responses across multiple stimulus parameters is systematic, that is the same for all cells, and separable, such that the response to a stimulus is a product of the effects of each stimulus parameter alone. We extracellularly recorded single On-Off DS RGCs in a superfused eyecup preparation while stimulating them with moving bars. We found that spike count responses of these cells scaled as independent functions of direction, speed, and luminance. Moreover, the speed and luminance functions were common across the whole sample of cells. Based on these findings, we developed a model that accurately predicted responses of On-Off DS RGCs as products of separable functions of direction, speed, and luminance (r = 0.98;P < 0.0001). Such a multiplicatively separable encoding strategy may simplify the decoding of these cells' outputs by the higher visual centers.

关键词： population coding tuning curve receptive field trigger feature visual motion

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Effects of V1 surround modulation tuning on visual saliency and the tilt illusion

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JOURNAL OF NEUROPHYSIOLOGY 2018年第3期120卷 942-952页

作者： Keemink, Sander W. Roucsein, Clemens van Rossum, Mark C. W. Univ Edinburgh Sch Informat Inst Adapt & Neural Computat Edinburgh EH8 9AB Midlothian Scotland Univ Freiburg Fac Biol Bernstein Ctr Freiburg Freiburg Germany

Neurons in the primary visual cortex respond to oriented stimuli placed in the center of their receptive field, yet their response is modulated by stimuli outside the receptive field (the surround). Classically, this surround modulation is assumed to be strongest if the orientation of the surround stimulus aligns with the neuron's preferred orientation, irrespective of the actual center stimulus. This neuron-dependent surround modulation has been used to explain a wide range of psychophysical phenomena, such as biased tilt perception and saliency of stimuli with contrasting orientation. However, several neurophysiological studies have shown that for most neurons surround modulation is instead center dependent: it is strongest if the surround orientation aligns with the center stimulus. As the impact of such center-dependent modulation on the population level is unknown, we examine this using computational models. We find that with neuron-dependent modulation the biases in orientation coding, commonly used to explain the tilt illusion, are larger than psycho physically reported, but disappear with center-dependent modulation. Therefore we suggest that a mixture of the two modulation types is necessary to quantitatively explain the psychophysically observed biases. Next, we find that under center-dependent modulation average population responses are more sensitive to orientation differences between stimuli, which in theory could improve saliency detection. However, this effect depends on the specific saliency model. Overall, our results thus show that center-dependent modulation reduces coding bias, while possibly increasing the sensitivity to salient features. NEW & NOTEWORTHY Neural responses in the primary visual cortex are modulated by stimuli surrounding the receptive field. Most earlier studies assume this modulation depends on the neuron's tuning properties, but experiments have shown that instead it depends mostly on the stimulus characteristics. We show that

关键词： orientation saliency population coding surround modulation tilt illusion

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