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  <head>
    <title>027-02 Population coding, predictive perception, and persistent pain networks</title>
    <ownerName>Integrated Medical Foundations</ownerName>
  </head>
  <body>
    <outline text="Population coding, prediction, and persistent pain">
      <outline text="Distributed neural information">
        <outline text="No single spike carries stimulus identity"/>
        <outline text="Which neurons, rate, timing, synchrony, network state"/>
        <outline text="Population codes represent continuous ranges"/>
        <outline text="Rate coding limited by refractoriness and cost"/>
        <outline text="Temporal coding uses precise spike timing"/>
        <outline text="Recruitment extends dynamic range"/>
        <outline text="Adaptation devotes activity to change"/>
        <outline text="Perception combines evidence with prior expectation">
          <outline text="Overly strong priors cause illusion and threat bias"/>
        </outline>
      </outline>
      <outline text="Receptive fields and contrast">
        <outline text="Central field differs from transduction zone">
          <outline text="Convergence enlarges, inhibition sharpens"/>
        </outline>
        <outline text="Small fields and dense innervation give acuity"/>
        <outline text="Lateral inhibition raises edge contrast">
          <outline text="Retinal centre-surround highlights change"/>
          <outline text="Improves two-point discrimination"/>
        </outline>
        <outline text="Convergence raises sensitivity, lowers localisation">
          <outline text="Visceral-somatic convergence explains referred pain"/>
        </outline>
        <outline text="Divergence spreads noxious input to many systems"/>
      </outline>
      <outline text="Synaptic gain and network state">
        <outline text="Release, receptors, driving force, location"/>
        <outline text="Inhibition near axon initial segment is strong"/>
        <outline text="Shunting inhibition without large hyperpolarisation"/>
        <outline text="Neuromodulators change gain, not on or off">
          <outline text="Noradrenaline: arousal and signal-to-noise"/>
          <outline text="Acetylcholine: attention and plasticity"/>
          <outline text="Dopamine: salience, learning, action value"/>
        </outline>
        <outline text="Astrocytes clear glutamate and potassium">
          <outline text="Failed uptake promotes seizures, excitotoxicity"/>
        </outline>
        <outline text="Microglial signalling changes synapses in pain"/>
      </outline>
      <outline text="Adaptation and sensitisation">
        <outline text="Rapid adaptation detects vibration and movement"/>
        <outline text="Slow adaptation encodes pressure and position"/>
        <outline text="Inflammatory mediators phosphorylate channels"/>
        <outline text="Repeated input removes magnesium block">
          <outline text="Calcium, transcription, stronger dorsal horn"/>
        </outline>
        <outline text="Sensory loss can coexist with pain">
          <outline text="Ectopic impulses, cross-excitation, central gain"/>
        </outline>
      </outline>
      <outline text="Visual computation">
        <outline text="Photoreceptors reduce release when hyperpolarised"/>
        <outline text="Bipolar pathways create on and off channels"/>
        <outline text="Colour compares cone classes">
          <outline text="Constancy infers reflectance from context"/>
        </outline>
        <outline text="Depth from many cues, one loss is tolerated"/>
        <outline text="Streams for identity, space, and action"/>
        <outline text="Ordered geometry localises field defects">
          <outline text="Optic nerve: monocular loss"/>
          <outline text="Chiasm: bitemporal fields"/>
          <outline text="Post-chiasm: contralateral homonymous defect"/>
        </outline>
      </outline>
      <outline text="Auditory and vestibular inference">
        <outline text="Travelling wave converts frequency to place"/>
        <outline text="Outer hair cell damage raises thresholds"/>
        <outline text="Conductive loss spares cochlear machinery"/>
        <outline text="Sensorineural loss distorts speech"/>
        <outline text="Tuning forks screen, audiometry quantifies"/>
        <outline text="Low frequency by timing, high by intensity"/>
        <outline text="Sudden unilateral sensorineural loss is urgent"/>
        <outline text="Vestibulo-ocular reflex stabilises vision">
          <outline text="Central lesions may not suppress with fixation"/>
        </outline>
      </outline>
      <outline text="Pain as protective inference">
        <outline text="Nociception encodes threat, pain is experience">
          <outline text="Anaesthesia blocks pain despite injury"/>
          <outline text="Sensitisation sustains pain after danger"/>
        </outline>
        <outline text="Peripheral sensitisation makes tissue tender"/>
        <outline text="Central sensitisation reduces inhibition"/>
        <outline text="Attention, fear, sleep, mood modify pain">
          <outline text="Graded safe experience updates predictions"/>
        </outline>
      </outline>
      <outline text="Neuropathic and nociplastic patterns">
        <outline text="Neuropathic distribution fits anatomy">
          <outline text="Positive signs: burning, shocks, allodynia"/>
          <outline text="Negative signs: reduced sensation"/>
        </outline>
        <outline text="Nociplastic: pathology does not explain extent">
          <outline text="Widespread sensitivity, fatigue, poor sleep"/>
        </outline>
        <outline text="Mechanisms often overlap in one patient"/>
        <outline text="Match treatment to dominant mechanism"/>
        <outline text="Opioid benefit shown by function and harm review"/>
      </outline>
      <outline text="Plasticity, formulation, and reassessment">
        <outline text="Cortical maps change after amputation or injury">
          <outline text="Phantom sensation reflects central representation"/>
        </outline>
        <outline text="Mirror therapy and graded motor imagery"/>
        <outline text="Plasticity is neither always good nor limitless"/>
        <outline text="Formulation names pathway, signs, amplification"/>
        <outline text="Separate urgent new injury from network change"/>
        <outline text="Examination is the baseline for testing">
          <outline text="Reassess by the same method after intervention"/>
        </outline>
        <outline text="Function can improve without lower intensity"/>
      </outline>
    </outline>
  </body>
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