1 Modulation Channels in Biomimic Artificial Neurons Richard B. Wells

2 The Biomimic Concept Purpose: Lay Out the General Architecture for Biomimic Neurons Biomimic is a Subset of Biomimetic –Biomimic = Mimicking the Neuron or Glial Cell The Artificial Neuron as a State Machine –Classical Artificial Neurons After Training Are “Combinational Analog Logic” –Biological Neurons Are Better Modeled as Analog State Machines “Information relates not so much to what you do say as to what you could say –Warren Weaver, 1964

3 Short-Term vs. Long-Term Adaptation Conventional Adaptation = LTP, LTD Modulation = Short-Term Adaptation Short-Term Modulations => The Neuron as a State Machine “In order to understand the style of computation practiced by nervous systems, we must study their hardware.” –Christof Koch, 1999

4 Three Basic Modulation Mechanisms in Biological Neurons Voltage-Gated Ionic Channels (VGCs) –Classical Hodgkin-Huxley Model –Generally NOT “Inputs” (NMDA = ?) Ionotropic Channels -Synaptic Signal Inputs Metabotropic Receptors – “Control Inputs” –“Intrinsic” vs. “Extrinsic” Information?

5 Voltage-Gated Channels VGCs Most Directly Control the Action Potential They Are “Feedback Circuits” Mediated Through the Integration of Membrane Potential They Occur in Great Variety but Follow A Generalized Architectural Scheme

6 Inactivating & Non-inactivating VGCs

7 Principal Classes of VGCs

8 Ionotropic Channels Principal Transmission Inputs of Neuron IC s Recruit VGCs Through PSPs

9 The IC Synapse is a State Machine Basic Mode is a Non-Retriggerable Monostable Multivibrator Tetanic Facilitation = Input-Dependent Synaptic Weight Delay, Conduction Time Can Be Modulated (Phosphorylation)

10 Metabotropic Receptor Processes Their Role is Entirely Modulatory 2 nd Messenger Processes Essential for Stabilization of Synaptic Weight Changes (LTP, LTD) Indirect Effects on Ion Current Flow, Generation of Retrograde Messengers, Modulation of IC Neurotransmitter Actions They Have Traditionally Been Ignored in Artificial Neurons

11 Comparison of MSMS and IC

12 Primary Systems & Effects

13 Putting It All Together

14 Thank You. Questions?