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Hierarchical effects of task engagement on amplitude modulation encoding in auditory cortex

JOURNAL OF NEUROPHYSIOLOGY 2015年第1期113卷 307-327页

作者： Niwa, Mamiko O'Connor, Kevin N. Engall, Elizabeth Johnson, Jeffrey S. Sutter, M. L. Univ Calif Davis Ctr Neurosci Davis CA 95616 USA Univ Calif Davis Dept Neurobiol Physiol & Behav Davis CA 95616 USA

We recorded from middle lateral belt (ML) and primary (A1) auditory cortical neurons while animals discriminated amplitude-modulated (AM) sounds and also while they sat passively. Engagement in AM discrimination improved ML and A1 neurons' ability to discriminate AM with both firing rate and phase-locking;however, task engagement affected neural AM discrimination differently in the two fields. The results suggest that these two areas utilize different AM coding schemes: a "single mode" in A1 that relies on increased activity for AM relative to unmodulated sounds and a "dual-polar mode" in ML that uses both increases and decreases in neural activity to encode modulation. In the dual-polar ML code, nonsynchronized responses might play a special role. The results are consistent with findings in the primary and secondary somatosensory cortices during discrimination of vibrotactile modulation frequency, implicating a common scheme in the hierarchical processing of temporal information among different modalities. The time course of activity differences between behaving and passive conditions was also distinct in A1 and ML and may have implications for auditory attention. At modulation depths >= 16% (approximately behavioral threshold), A1 neurons' improvement in distinguishing AM from unmodulated noise is relatively constant or improves slightly with increasing modulation depth. In ML, improvement during engagement is most pronounced near threshold and disappears at highly suprathreshold depths. This ML effect is evident later in the stimulus, and mainly in nonsynchronized responses. This suggests that attention-related increases in activity are stronger or longer-lasting for more difficult stimuli in ML.

关键词： auditory cortex attention sound processing neural coding

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Coherent Infomax as a Computational Goal for neural Systems

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BULLETIN OF MATHEMATICAL BIOLOGY 2011年第2期73卷 344-372页

作者： Kay, Jim W. Phillips, W. A. Univ Glasgow Dept Stat Glasgow G12 8QQ Lanark Scotland Univ Stirling Dept Psychol Stirling FK9 4LA Scotland Goethe Univ Frankfurt Frankfurt Inst Adv Studies Frankfurt Germany

Signal processing in the cerebral cortex is thought to involve a common multi-purpose algorithm embodied in a canonical cortical micro-circuit that is replicated many times over both within and across cortical regions. Operation of this algorithm produces widely distributed but coherent and relevant patterns of activity. The theory of Coherent Infomax provides a formal specification of the objectives of such an algorithm. It also formally derives specifications for both the short-term processing dynamics and for the learning rules whereby the connection strengths between units in the network can be adapted to the environment in which the system finds itself. A central assumption of the theory is that the local processors can combine reliable signal coding with flexible use of those codes because they have two classes of synaptic connection: driving connections which specify the information content of the neural signals, and contextual connections which modulate that signal processing. Here, we make the biological relevance of this theory more explicit by putting more emphasis upon the contextual guidance of ongoing processing, by showing that Coherent Infomax is consistent with a particular Bayesian interpretation for the contextual guidance of learning and processing, by explicitly specifying rules for on-line learning, and by suggesting approximations by which the learning rules can be made computationally feasible within systems composed of very many local processors.

关键词： neural networks Coherent Infomax Dynamic coordination Contextual modulation Learning rules Synaptic plasticity Bayesian analysis neural coding Information theory

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How do visual neurons respond in the real world?

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CURRENT OPINION IN NEUROBIOLOGY 2001年第4期11卷 437-442页

作者： Reinagel, P Harvard Univ Sch Med Dept Neurobiol Boston MA 02115 USA

Natural visual stimuli have been reported to evoke neural responses with brief, intense firing events. This has important implications for how visual information is encoded. A recent experiment measured the responses of visual neurons in the natural environment, circumventing many limitations of laboratory simulations while still retaining tight experimental control. Under these conditions, neurons fired intensely at precise, discrete times, validating that this firing regime is relevant to natural vision.

关键词： natural scenes natural stimuli vision motion neural coding sparse neuroethology fly monkey cat

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Feedback Synthesizes neural Codes for Motion

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CURRENT BIOLOGY 2017年第9期27卷 1356-1361页

作者： Clarke, Stephen E. Maler, Leonard Univ Ottawa Dept Cellular & Mol Med 451 Smyth Rd Ottawa ON K1H 8M5 Canada Univ Ottawa Brain & Mind Inst 451 Smyth Rd Ottawa ON K1H 8M5 Canada Univ Ottawa Ctr Neural Dynam 451 Smyth Rd Ottawa ON K1H 8M5 Canada

In senses as diverse as vision, hearing, touch, and the electrosense, sensory neurons receive bottom-up input from the environment, as well as top-down input from feedback loops involving higher brain regions [1-4]. Through connectivity with local inhibitory interneurons, these feedback loops can exert both positive and negative control over fundamental aspects of neural coding, including bursting [5, 6] and synchronous population activity [7, 8]. Here we show that a prominent midbrain feedback loop synthesizes a neural code for motion reversal in the hindbrain electrosensory ON-and OFF-type pyramidal cells. This top-down mechanism generates an accurate bidirectional encoding of object position, despite the inability of the electrosensory afferents to generate a consistent bottom-up representation [9, 10]. The net positive activity of this midbrain feedback is additionally regulated through a hindbrain feedback loop, which reduces stimulus-induced bursting and also dampens the ON and OFF cell responses to interfering sensory input [11]. We demonstrate that synthesis of motion representations and cancellation of distracting signals are mediated simultaneously by feedback, satisfying an accepted definition of spatial attention [12]. The balance of excitatory and inhibitory feedback establishes a "focal'' distance for optimized neural coding, whose connection to a classic motion-tracking behavior provides new insight into the computational roles of feedback and active dendrites in spatial localization [13, 14].

关键词： top-down processing topographic feedback neural coding burst spiking spatial attention motion tracking ON and OFF cells electric fish cerebellum gain control

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Slip-Based coding of Local Shape and Texture in Mouse S1

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NEURON 2018年第2期97卷 418-+页

作者： Isett, Brian R. Feasel, Sierra H. Lane, Monet A. Feldman, Daniel E. Univ Calif Berkeley Dept Mol & Cell Biol Berkeley CA 94720 USA Univ Calif Berkeley Helen Wills Neurosci Inst Berkeley CA 94720 USA

Tactile objects have both local geometry (shape) and broader macroscopic texture, but how these different spatial scales are simultaneously encoded during active touch is unknown. In the whisker system, we tested for a shared code based on localized whisker micromotions (stick-slips) and slip-evoked spikes. We trained mice to discriminate smooth from rough surfaces, including ridged gratings and sandpaper. Whisker slips locked to ridges and evoked temporally precise spikes (<10 ms jitter) in somatosensory cortex (S1) that could resolve ridges with similar to 1 mm accuracy. Slip-sensitive neurons also encoded touch and texture. On rough surfaces, both slip-evoked spikes and an additional non-slip signal elevated mean firing rate, allowing accurate rough-smooth texture decoding from population firing rate. Eighteen percent of neurons were selective among rough surfaces. Thus, slips elicit spatially and temporally precise spiking in S1 that simultaneously encodes local shape (ridges) and is integrated into a macroscopic firing rate code for roughness.

关键词： neural coding barrel cortex texture shape spatial tuning active sensation virtual foraging stick-slip multiplexed code S1 cortex

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Sugar response differences related to sensillum type and location on the labella of Protophormia terraenovae:: a contribution to spatial representation of the stimulus.

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JOURNAL OF INSECT PHYSIOLOGY 1998年第5-6期44卷 471-481页

作者： Liscia, A Majone, R Solari, P Barbarossa, IT Crnjar, R Univ Cagliari Sect Gen Physiol Dept Expt Biol I-09126 Cagliari Italy

The chemoreceptor spike activity in response to sucrose in the concentration range 1-500 mM was recorded from each of the 11 Intermediate and 13 Large labellar sensilla in the blowfly Protophormia terraenovae. The results showed that: (1) three of the four cells present in each sensillum are activated by sucrose stimulation: (2) differences between the Large and Intermediate types exist in the dose-response profiles of one of these cells (the 'water' cell), possibly reflecting different sugar receptor site populations on the dendritic membranes of homologous cells in the two types, (3) sensilla of both types are differentially responsive to sucrose solutions according to their location on the labellum. These differences may provide elements for a spatial representation of the stimulus source within the sensory coding process. (C) 1998 Elsevier Science Ltd. All rights reserved.

关键词： blowfly taste sugar receptor water receptor neural coding

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Relationships among low-frequency local field potentials, spiking activity, and three-dimensional reach and grasp kinematics in primary motor and ventral premotor cortices

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JOURNAL OF NEUROPHYSIOLOGY 2011年第4期105卷 1603-1619页

作者： Bansal, Arjun K. Vargas-Irwin, Carlos E. Truccolo, Wilson Donoghue, John P. Brown Univ Dept Neurosci Providence RI 02912 USA Brown Univ Brown Inst Brain Sci Providence RI 02912 USA Massachusetts Gen Hosp Dept Neurol Boston MA 02114 USA Vet Affairs Med Ctr Rehabilitat Res & Dev Serv Providence RI USA

Bansal AK, Vargas-Irwin CE, Truccolo W, Donoghue JP. Relationships among low-frequency local field potentials, spiking activity, and three-dimensional reach and grasp kinematics in primary motor and ventral premotor cortices. J Neurophysiol 105: 1603-1619, 2011. First published January 27, 2011;doi: 10.1152/jn.00532.2010.-A prominent feature of motor cortex field potentials during movement is a distinctive low-frequency local field potential (lf-LFP) (< 4 Hz), referred to as the movement event-related potential (mEP). The lf-LFP appears to be a global signal related to regional synaptic input, but its relationship to nearby output signaled by single unit spiking activity (SUA) or to movement remains to be established. Previous studies comparing information in primary motor cortex (MI) lf-LFPs and SUA in the context of planar reaching tasks concluded that lf-LFPs have more information than spikes about movement. However, the relative performance of these signals was based on a small number of simultaneously recorded channels and units, or for data averaged across sessions, which could miss information of larger-scale spiking populations. Here, we simultaneously recorded LFPs and SUA from two 96-microelectrode arrays implanted in two major motor cortical areas, MI and ventral premotor (PMv), while monkeys freely reached for and grasped objects swinging in front of them. We compared arm end point and grip aperture kinematics' decoding accuracy for lf-LFP and SUA ensembles. The results show that lf-LFPs provide enough information to reconstruct kinematics in both areas with little difference in decoding performance between MI and PMv. Individual lf-LFP channels often provided more accurate decoding of single kinematic variables than any one single unit. However, the decoding performance of the best single unit among the large population usually exceeded that of the best single lf-LFP channel. Furthermore, ensembles of SUA outperformed the pool of lf-LFP channels, in dis

关键词： motor cortex neural signals neural coding brain-machine interfaces neural prosthesis

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Conditioned spikes:: a simple and fast method to represent rates and temporal patterns in multielectrode recordings

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JOURNAL OF NEUROSCIENCE METHODS 2004年第1-2期133卷 135-141页

作者： Ortega, GJ Bongard, M Louis, E Fernández, E Univ Miguel Hernandez Inst Bioingn Fac Med Alicante 03550 Spain Univ Buenos Aires FCEN Dept Fis RA-1053 Buenos Aires DF Argentina Consejo Nacl Invest Cient & Tecn RA-1033 Buenos Aires DF Argentina Univ Alicante Dept Fis Aplicada E-03080 Alicante Spain Univ Alicante CSIC E-03080 Alicante Spain

Increasing evidence suggests that the brain utilizes distributed codes that can only be analyzed by simultaneously recording the activity of multiple neurons. This paper introduces a new methodology for studying neural ensemble recordings. The method uses a novel representation to provide complementary information about the stimuli which are contained in the temporal pattern of the spike sequence. By using this procedure, a high correlation of synchronized events with stimuli times is apparent. To quantify the results and to compare the performance of this method against the most traditional raster plot, we have used Fano factor and cross-correlation analysis. Our results suggest that several consecutive spikes from different neurons within an extended time window may encode behaviorally relevant information. We propose that this new representation, in addition to the other approaches currently used (standard raster plots, multivariate statistical methods, neuronal networks, information theory, etc.), can be a useful procedure to describe population spike dynamics. (C) 2003 Elsevier B.V. All rights reserved.

关键词： neural coding conditioned spikes neural ensembles multineuronal recording visual system retina

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Developmental Experience Alters Information coding in Auditory Midbrain and Forebrain Neurons

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DEVELOPMENTAL NEUROBIOLOGY 2010年第4期70卷 235-252页

作者： Woolley, Sarah M. N. Hauber, Mark E. Theunissen, Frederic E. Columbia Univ Dept Psychol New York NY 10027 USA CUNY Hunter Coll Dept Psychol New York NY 10065 USA Univ Auckland Sch Biol Sci Auckland 1 New Zealand Univ Calif Berkeley Dept Psychol Berkeley CA 94720 USA

In songbirds, species identity and developmental experience shape vocal behavior and behavioral responses to vocalizations. The interaction of species identity and developmental experience may also shape the coding, properties of sensor neurons. We tested whether responses of auditory midbrain and forebrain neurons to songs differed between species and between groups of conspecific birds with different developmental exposure to song. We also compared responses of individual neurons to conspecific and heterospecific songs. Zebra and Bengalese finches that were raised and tutored by, conspecific birds, and zebra finches that were cross-tutored by Bengalese finches were studied. Single-unit responses to zebra and Bengalese finch songs were recorded and analyzed by calculating mutual information (MI). response reliability. mean spike rate, fluctuations in time-varying spike rate. distributions of time-varying spike rates. and neural discrimination of individual Songs. MI (quantities a response's capacity to encode information about a stimulus. In midbrain and forebrain neurons, M1 was significantly higher in normal zebra finch neurons than in Bengalese finch and cross-tutored zebra finch neurons, but not between Bengalese finch and cross-tutored zebra finch neurons. Information rate differences were largely due to spike rate differences. M1 did not differ between responses to conspecific and heterospecific songs. Therefore, neurons from normal zebra finches encoded more information about songs than (fill neurons from other birds, but conspecific and heterospecific songs were encoded equally. neural discrimination of songs and M1 were highly correlated. Results demonstrate that developmental exposure to vocalizations shapes file information coding properties of songbird auditory neurons. (C) 2009 Wiley Periodicals. Inc Develop Neurobiol 70 235-252, 2010

关键词： inferior colliculus vocalization songbird neural coding song

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Emergence of an Invariant Representation of Texture in Primate Somatosensory Cortex

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CEREBRAL CORTEX 2020年第5期30卷 3228-3239页

作者： Lieber, Justin D. Bensmaia, Sliman J. Univ Chicago Comm Computat Neurosci Chicago IL 60637 USA Univ Chicago Dept Organismal Biol & Anat Chicago IL 60637 USA

A major function of sensory processing is to achieve neural representations of objects that are stable across changes in context and perspective. Small changes in exploratory behavior can lead to large changes in signals at the sensory periphery, thus resulting in ambiguous neural representations of objects. Overcoming this ambiguity is a hallmark of human object recognition across sensory modalities. Here, we investigate how the perception of tactile texture remains stable across exploratory movements of the hand, including changes in scanning speed, despite the concomitant changes in afferent responses. To this end, we scanned a wide range of everyday textures across the fingertips of rhesus macaques at multiple speeds and recorded the responses evoked in tactile nerve fibers and somatosensory cortical neurons (from Brodmann areas 3b, 1, and 2). We found that individual cortical neurons exhibit a wider range of speed-sensitivities than do nerve fibers. The resulting representations of speed and texture in cortex are more independent than are their counterparts in the nerve and account for speed-invariant perception of texture. We demonstrate that this separation of speed and texture information is a natural consequence of previously described cortical computations.

关键词： neural coding invariance touch neural computation neural manifolds

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