Metabolic efficiency of action potentials in fast-spiking vs pyramidal neurons

The metabolic efficiency of fast-spiking neuron APs depends on the subcellular compartment measured. Somatic recordings show 2x theoretical minimum sodium entry (metabolically expensive), but direct axonal recordings reveal only 1.6x minimum due to optimized Na+/K+ channel gating. Pyramidal neurons are most efficient at 1.25x. This demonstrates that the narrow spikes of FS neurons entail a metabolic cost, but complementary channel tuning at the axon partially compensates.

{
  "papers": [
    {
      "n": 0,
      "doi": "10.1016/j.neuron.2009.12.011",
      "value": "2.0",
      "method": "sodium imaging during APs",
      "metric": "Sodium entry relative to theoretical minimum (somatic)",
      "n_analyzed": "cortical FS interneurons",
      "ci_or_error": null,
      "text_access": "fulltext",
      "n_definition": "neurons recorded at soma at 37°C",
      "scope_region": "cortex",
      "study_system": "mouse cortical interneurons",
      "taxonomic_level": "cell class (FS)",
      "scope_population": "fast-spiking GABAergic interneurons",
      "value_source_sentence": "in fast-spiking GABAergic neurons, twice as much sodium enters as the theoretical minimum.",
      "experimental_conditions": "somatic recordings at 37°C"
    },
    {
      "n": 0,
      "doi": "10.1016/j.neuron.2009.12.011",
      "value": "1.25",
      "method": "sodium imaging during APs",
      "metric": "Sodium entry relative to theoretical minimum (pyramidal)",
      "n_analyzed": "cortical pyramidal neurons",
      "ci_or_error": null,
      "text_access": "fulltext",
      "n_definition": "neurons recorded at soma at 37°C",
      "scope_region": "cortex",
      "study_system": "mouse cortical pyramidal neurons",
      "taxonomic_level": "cell class (excitatory)",
      "scope_population": "pyramidal neurons",
      "value_source_sentence": "only ~25% more sodium enters than the theoretical minimum necessary for spike depolarization.",
      "experimental_conditions": "somatic recordings at 37°C"
    },
    {
      "n": 0,
      "doi": "10.1016/j.neuron.2018.02.024",
      "value": "1.6",
      "method": "axonal patch-clamp electrophysiology",
      "metric": "Energy efficiency relative to theoretical minimum (PV axon)",
      "n_analyzed": "PV+ basket cell axons",
      "ci_or_error": null,
      "text_access": "fulltext",
      "n_definition": "direct axonal recordings from PV+-BCs",
      "scope_region": "cortex/hippocampus",
      "study_system": "PV+ basket cell axons",
      "taxonomic_level": "subcellular (axon)",
      "scope_population": "PV+ basket cell axons specifically",
      "value_source_sentence": "the energy required for the AP was, on average, only ~1.6 times the theoretical minimum.",
      "experimental_conditions": "direct axonal patch-clamp recordings"
    }
  ],
  "comparison_id": "sodium-entry-efficiency",
  "comparison_name": "Metabolic efficiency of action potentials in fast-spiking vs pyramidal neurons",
  "comparison_type": "cross-study conflict",
  "what_it_reveals": "The metabolic efficiency of fast-spiking neuron APs depends on the subcellular compartment measured. Somatic recordings show 2x theoretical minimum sodium entry (metabolically expensive), but direct axonal recordings reveal only 1.6x minimum due to optimized Na+/K+ channel gating. Pyramidal neurons are most efficient at 1.25x. This demonstrates that the narrow spikes of FS neurons entail a metabolic cost, but complementary channel tuning at the axon partially compensates.",
  "homogeneity_check": {
    "caveats": [
      "Different subcellular compartments: soma vs axon",
      "Different methods: sodium imaging vs patch-clamp",
      "Different cell populations: generic FS vs specifically PV+ basket cells",
      "Energy vs sodium entry are related but not identical metrics"
    ],
    "n_definition_uniform": "false",
    "scope_region_uniform": "true",
    "taxonomic_level_uniform": "false",
    "scope_population_uniform": "false"
  },
  "suggested_plot_type": "bar chart"
}

[
  "paper:paper-5913a3633195",
  "paper:paper-e022e0b961a0"
]

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  "source_commit_sha": "df9fc7e8d455b084152c9d713558dae0013cef21",
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