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. 2011 Sep 22:5:108.
doi: 10.3389/fnins.2011.00108. eCollection 2011.

Neuromorphic silicon neurons and large-scale neural networks: challenges and opportunities

Chi-Sang Poon  1 , Kuan Zhou
Affiliations

Neuromorphic silicon neurons and large-scale neural networks: challenges and opportunities

Chi-Sang Poon et al. Front Neurosci. .
No abstract available

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Figures

Figure 1
Figure 1
Biological and silicon neurons have much better power and space efficiencies than digital computers. A biological neuron consumes approximately 3. 84 × 108 ATP molecules in generating a spike (Attwell and Laughlin, ; Lennie, 2003). Assuming 30–45 kJ released per mole of ATP (Berg et al., ; or 5–7.5 × 10−20 J per ATP molecule), the energy cost of a neuronal spike is in the order of 10−11 J. The density of neurons under cortical surface in various mammalian species is ~100,000/mm2 (Braitenberg and Schüz, 1998), which translates to a span of ~10 μm2 per neuron. Silicon neurons have power consumption in the order of 10−8 J/spike on a biological timescale. For example, an Integrate-and-Fire neuron circuit consumes 3–15 nJ at 100 Hz (Indiveri, 2003) and a compact neuron model consumes 8.5–9.0 pJ at ~1 MHz (Wijekoon and Dudek, 2008), which translates to 85–90 nJ at 100 Hz. For silicon neurons, the on-chip neuron area is estimated to be ~4,000 μm2 (70 μm × 40 μm in Wijekoon and Dudek, , ~3750 μm2 in Vogelstein et al., , and 70 μm × 70 μm in Wijekoon and Dudek, 2009). According to Liu and Delbrück (2007), digital computers are 104–108 less efficient than biological neurons. The power efficiency of digital computers is therefore estimated to be 10−3–10−7 J/spike. Most current multi-core digital microprocessor chips have dimensions from 263 to 692 mm2. A single core has an average size from ~50 to ~90 mm2.
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