Recursos de colección

Caltech Authors (142.336 recursos)

Repository of works by Caltech published authors.

Group = Koch Laboratory (KLAB)

Mostrando recursos 1 - 5 de 5

  1. Slow synaptic transmission in frog sympathetic ganglia

    Adams, P. R.; Jones, S. W.; Pennefather, P.; Brown, D. A.; Koch, Christof; Lancaster, B.
    Bullfrog ganglia contain two classes of neurone, B and C cells, which receive different inputs and exhibit different slow synaptic potentials. B cells, to which most effort has been directed, possess slow and late slow EPSPs. The sEPSP reflects a muscarinic action of acetylcholine released from boutons on B cells, whereas the late sEPSP is caused by a peptide (similar to teleost LHRH) released from boutons on C cells. During either sEPSP there is a selective reduction in two slow potassium conductances, designated ‘M’ and ‘AHP’. The M conductance is voltage dependent and the AHP conductance is calcium dependent. Normally...
    (application/pdf) - 20-nov-2015

  2. Spatial vision thresholds in the near absence of attention

    Lee, Dale K.; Koch, Christof; Braun, Jochen
    It is well known that attention increases the discriminability of some types of spatial information. To ascertain more specifically which types of spatial information benefit from attention, we have measured spatial vision thresholds both in the presence and in the near absence of attention. To obtain near absence of attention, we induce subjects to focus attention elsewhere in the display by means of a suitably demanding concurrent visual task. We measure contrast and orientation thresholds for sine-wave gratings, as well uni- and bidirectional offset thresholds for vernier targets. The results suggest that attention selectively lowers some thresholds but not others:...
    (application/pdf) - 17-sep-2013

  3. Spatial vision thresholds in the near absence of attention

    Lee, Dale K.; Koch, Christof; Braun, Jochen
    It is well known that attention increases the discriminability of some types of spatial information. To ascertain more specifically which types of spatial information benefit from attention, we have measured spatial vision thresholds both in the presence and in the near absence of attention. To obtain near absence of attention, we induce subjects to focus attention elsewhere in the display by means of a suitably demanding concurrent visual task. We measure contrast and orientation thresholds for sine-wave gratings, as well uni- and bidirectional offset thresholds for vernier targets. The results suggest that attention selectively lowers some thresholds but not others:...
    (application/pdf) - 19-sep-2013

  4. A Meta-Theory of Boundary Detection Benchmarks

    Hou, Xiaodi; Yuille, Alan; Koch, Christof
    Human labeled datasets, along with their corresponding evaluation algorithms, play an important role in boundary detection. We here present a psychophysical experiment that addresses the reliability of such benchmarks. To find better remedies to evaluate the performance of any boundary detection algorithm, we propose a computational framework to remove inappropriate human labels and estimate the instrinsic properties of boundaries.
    (application/pdf) - 28-ago-2013

  5. A bottom–up model of spatial attention predicts human error patterns in rapid scene recognition

    Einhäuser, Wolfgang; Mundhenk, T. Nathan; Baldi, Pierre; Koch, Christof; Itti, Laurent
    Humans demonstrate a peculiar ability to detect complex targets in rapidly presented natural scenes. Recent studies suggest that (nearly) no focal attention is required for overall performance in such tasks. Little is known, however, of how detection performance varies from trial to trial and which stages in the processing hierarchy limit performance: bottom–up visual processing (attentional selection and/or recognition) or top–down factors (e.g., decision-making, memory, or alertness fluctuations)? To investigate the relative contribution of these factors, eight human observers performed an animal detection task in natural scenes presented at 20 Hz. Trial-by-trial performance was highly consistent across observers, far exceeding...
    (application/pdf) - 17-sep-2013

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