Houweling, A. R. & Brecht, M. Behavioural report of single neuron stimulation in somatosensory cortex. Nature 451, 65-68

Bernstein Center for Computational Neuroscience and Humboldt University Berlin, Philippstrasse 13, House 6, 10115 Berlin, Germany.
Nature (Impact Factor: 41.46). 02/2008; 451(7174):65-8. DOI: 10.1038/nature06447
Source: PubMed


Understanding how neural activity in sensory cortices relates to perception is a central theme of neuroscience. Action potentials of sensory cortical neurons can be strongly correlated to properties of sensory stimuli and reflect the subjective judgements of an individual about stimuli. Microstimulation experiments have established a direct link from sensory activity to behaviour, suggesting that small neuronal populations can influence sensory decisions. However, microstimulation does not allow identification and quantification of the stimulated cellular elements. The sensory impact of individual cortical neurons therefore remains unknown. Here we show that stimulation of single neurons in somatosensory cortex affects behavioural responses in a detection task. We trained rats to respond to microstimulation of barrel cortex at low current intensities. We then initiated short trains of action potentials in single neurons by juxtacellular stimulation. Animals responded significantly more often in single-cell stimulation trials than in catch trials without stimulation. Stimulation effects varied greatly between cells, and on average in 5% of trials a response was induced. Whereas stimulation of putative excitatory neurons led to weak biases towards responding, stimulation of putative inhibitory neurons led to more variable and stronger sensory effects. Reaction times for single-cell stimulation were long and variable. Our results demonstrate that single neuron activity can cause a change in the animal's detection behaviour, suggesting a much sparser cortical code for sensations than previously anticipated.

    • "Single mammalian pyramidal cells are not thought to have major effects on the cortical networks to which they belong (Shadlen & Newsome, 1998). Even so, single pyramidal cells of layers 5 and 6 of motor cortex can induce or affect whisker movements (Brecht et al, 2004) while stimulation of single layer 5 somatosensory pyramidal cells modifies behavioural responses during a detection task (Houweling & Brecht, 2008). Single neurones can also modify collective activities of cortical neuronal populations. "
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    ABSTRACT: Sharp waves (SPWs) are a hippocampal population activity that has been linked to neuronal representations. We show that SPWs in the CA3 region of rat hippocampal slices can be triggered by firing of single pyramidal cells. Single action potentials in about a third of pyramidal cells initiated SPWs at latencies of 2-5 ms with probabilities of 0.07-0.76. Initiating pyramidal cells evoked field IPSPs (fIPSPs) at similar latencies when SPWs were not initiated. Similar spatial profiles for fIPSPs and middle components of SPWs, suggested SPW fields reflect repeated fIPSPs. Multiple extracellular records showed initiated SPWs tended to start near the stimulated pyramidal cell, while spontaneous SPWs could emerge at multiple sites. Single pyramidal cells could initiate 2-6 field IPSPs with distinct amplitude distributions, and typically preceeded by a short-duration, extracellular action potential. Comparison of these initiated fields with spontaneously occurring inhibitory field motifs let us identify firing in different interneurones during the spread of SPWs. Propagation away from an initiating pyramidal cell was typically associated with the recruitment of interneurones and field IPSPs that were not activated by the stimulated pyramidal cell. SPW fields initiated by single cells were less variable than spontaneous events, suggesting more stereotyped neuronal ensembles were activated, but neither the spatial profile of fields nor the identities of interneurone firing were identical for initiated events. Single pyramidal cell effects on network events are thus mediated by differing sequences of interneurone firing. This article is protected by copyright. All rights reserved.
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    • "HMIs come in different forms, acting at different levels of the sensory-motor system. Sensory interfaces can transform sounds into cochlear stimuli (Shannon, 2012), images into stimuli to the visual cortex (Lewis et al., 2015; Gall et al., 2013), or stimulate the somatosensory cortex to generate an artificial proprioceptive sensation (Houweling and Brecht, 2008; Libet et al., 1964; Abbott, 2006). "
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    ABSTRACT: The concept of human motor redundancy attracted much attention since the early studies of motor control, as it highlights the ability of the motor system to generate a great variety of movements to achieve any single well-defined goal. The abundance of degrees of freedom in the human body may be a fundamental resource in the learning and remapping problems that are encountered in human-machine interfaces (HMIs) developments. The HMI can act at different levels decoding brain signals or body signals to control an external device. The transformation from neural signals to device commands is the core of research on brain-machine interfaces (BMIs). However, while BMIs bypass completely the final path of the motor system, body-machine interfaces (BoMIs) take advantage of motor skills that are still available to the user and have the potential to enhance these skills through their consistent use. BoMIs empower people with severe motor disabilities with the possibility to control external devices, and they concurrently offer the opportunity to focus on achieving rehabilitative goals. In this study we describe a theoretical paradigm for the use of a BoMI in rehabilitation. The proposed BoMI remaps the user's residual upper body mobility to the two coordinates of a cursor on a computer screen. This mapping is obtained by principal component analysis (PCA). We hypothesize that the BoMI can be specifically programmed to engage the users in functional exercises aimed at partial recovery of motor skills, while simultaneously controlling the cursor and carrying out functional tasks, e.g. playing games. Specifically, PCA allows us to select not only the subspace that is most comfortable for the user to act upon, but also the degrees of freedom and coordination patterns that the user has more difficulty engaging. In this article, we describe a family of map modifications that can be made to change the motor behavior of the user. Depending on the characteristics of the impairment of each high-level spinal cord injury (SCI) survivor, we can make modifications to restore a higher level of symmetric mobility (left versus right), or to increase the strength and range of motion of the upper body that was spared by the injury. Results showed that this approach restored symmetry between left and right side of the body, with an increase of mobility and strength of all the degrees of freedom in the participants involved in the control of the interface. This is a proof of concept that our BoMI may be used concurrently to control assistive devices and reach specific rehabilitative goals. Engaging the users in functional and entertaining tasks while practicing the interface and changing the map in the proposed ways is a novel approach to rehabilitation treatments facilitated by portable and low-cost technologies. Copyright © 2015. Published by Elsevier Ltd.
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    • "Interestingly this is the amount of energy supplied by the " machinery " of the biological systems through glucose metabolism per second for a single neuron, the unit of thinking. That the activity of only one neuron can affect the organization of the activity of the entire cerebral cortices (Li et al., 2009) or determine the direction of a complex behavior (Houwelling & Brecht, 2008) has been shown experimentally. From Teilhard de Chardin's perspective what is more critical is the energy density of the human cerebrum during thinking. "
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    ABSTRACT: Teilhard de Chardin's integration of geobiological phenomena with philosophical and spiritual perspectives resulted in ideas, such as potentially quantifiable " spiritual energy " , the emergence of a " sphere of human thinking " (noosphere) as the next evolutionary stage of the biosphere, and the ultimate expansion of consciousness into the galaxy. Transformations of his concepts into contemporary values that effectively define cosmology, quantum biology, and human cerebral parameters could support his interpretations. Scaled quantification of basic universal energies match the magnitudes measured within the human cerebrum during thinking. Superposition of the magnetic fields associated with thinking upon the intergalactic strength fields for induced changes in magnetic moments of elementary electrons solves for durations that approach the age of the universe or " immortality ". The immersion of the human species within both the earth's magnetic field and the Schumann Resonances creates the conditions for producing the " noosphere " and for its potential expansion into space. The rapid development of new computer-based technologies that expose the human population to homogeneous energetic patterns and produce cog-nitive states consistent with " unifying " the noosphere could be sufficient to produce physical changes which would support Teilhard de Chardin's hypotheses.
    Full-text · Article · Aug 2015 · Open Journal of Philosophy
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