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ref: -0 tags: date: 01-09-2022 19:03 gmt revision:1 [0] [head]

Cortical response selectivity derives from strength in numbers of synapses

  • Benjamin Scholl, Connon I. Thomas, Melissa A. Ryan, Naomi Kamasawa & David Fitzpatrick
  • "Using electron microscopy reconstruction of individual synapses as a metric of strength, we find no evidence that strong synapses have a predominant role in the selectivity of cortical neuron responses to visual stimuli. Instead, selectivity appears to arise from the total number of synapses activated by different stimuli."
  • "Our results challenge the role of Hebbian mechanisms in shaping neuronal selectivity in cortical circuits, and suggest that selectivity reflects the co-activation of large populations of presynaptic neurons with similar properties and a mixture of strengths. "
    • Interesting -- so this is consistent with ANNs / feature detectors / vector hypothesis.
    • It would imply that the mapping is dense rather than sparse -- but to see this, you'd need to record the activity of all these synapses in realtime.
      • Which is possible, (e.g. lightbeads, fast axial focusing), just rather difficult for now.
  • To draw really firm conclusions, would need a thorough stimulus battery, not just drifting gratings.
    • It may change this result: "Surprisingly, the strength of individual synapses was uncorrelated with functional similarity to the somatic output (that is, absolute orientation preference difference)"