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.

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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.
    Open Journal of Philosophy 08/2015; 5(6):338-350. DOI:10.4236/ojpp.2015.56042
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    • "On the local network level, neuronal responses to a stimulus are both redundant and sparse (Houweling and Brecht, 2008; Kerr et al., 2007; O'Connor et al., 2010; Olshausen and Field, 2004). Redundancy, in which the total number of spikes elicited by a sensory stimulus exceeds the number needed for sensory perception (Houweling and Brecht, 2008; Huber et al., 2008; O'Connor et al., 2010), permits fault-tolerant coding in cortical networks, which have characteristically high response variability. However, redundant coding increases the metabolic load on the system. "
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    • "For recordings in the two-compartment maze (n = 17), animals were pre-implanted under ketamine/xylazine anesthesia (intraperitoneal doses of 100 and 10 mg/kg, respectively) according to previously published procedures (Houweling and Brecht, 2008; Herfst et al., 2012). After a recovery period (typically 2–3 days) animals were habituated to the familiar compartment of the two-compartment maze for 3–7 days (2–4 sessions per day, of 15 min–1 h duration each). "
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    ABSTRACT: Extracellular recordings in medial entorhinal cortex have revealed the existence of spatially-modulated firing patterns, which are thought to contribute to a cognitive map of external space. Previous work indicated that during exploration of novel environments, spiking activity in deep entorhinal layers is much sparser than in superficial layers. In the present report, we ask whether this laminar activity profile is a consequence of environmental novelty. We report on a large dataset of juxtacellularly-recorded neurons (n = 70) whose spiking activity was monitored while rats explored either a novel or a familiar environment, or both within the same session. Irrespective of previous knowledge of the environment, deep layer activity was very low during exploration (median firing rate 0.4 Hz for non-silent cells), with a large fraction of silent cells (n = 19 of a total 37), while superficial layer activity was several times higher (median firing rate 2.4 Hz; n = 33). The persistence of laminar differences in firing activity both under environmental novelty and familiarity, and even in head-restrained stationary animals, suggests that sparse coding might be a constitutive feature of deep entorhinal layers.
    Frontiers in Neural Circuits 07/2014; 8:74. DOI:10.3389/fncir.2014.00074
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