Introduction to Neuronal Networks PDF

Institute of Psychiatry, Psychology & Neuroscience Dr Philip R Holland 4BBY1003 Wolfson Centre for Age- Related Diseases Introduction to Neuronal Networks Clemens Kiecker (Phil Hollan...

Institute of Psychiatry, Psychology & Neuroscience Dr Philip R Holland 4BBY1003 Wolfson Centre for Age- Related Diseases Introduction to Neuronal Networks Clemens Kiecker (Phil Holland) DD/Month/YYYY Professor/Dr: Topic title: Learning Outcomes 1. Describe how neurons communicate with each other and the directionality of this communication 2. Explain how multiple signals are integrated by individual neuron 3. Describe simple neuronal networks (that are built from recurrent wiring motifs) and how they integrate information DD/Month/YYYY Professor/Dr: Topic title:  Direction of Travel from Neuron to Neuron Dendrites Cell Body Axon Dendrites receive incoming signals that converge in the cell body before being conveyed along the axon to transmit the signal in the form of an action potential to the target neuron. Professor/Dr: DD/Month/YYYY Topic title: Synaptic Communication DD/Month/YYYY Professor/Dr: Topic title: Synaptic Communication DD/Month/YYYY Professor/Dr: Topic title: Synaptic Communication Ca2+ Ca2+ Ca2+ Resting synapse AP arrives, V-gated Ca2+ channels open DD/Month/YYYY Professor/Dr: Topic title: Synaptic Communication Ca2+ entry triggers exocytosis NT diffuses across the of synaptic vesicle content synaptic cleft and activates DD/Month/YYYY Professor/Dr: Topic title: postsynaptic cell Synaptic Communication DD/Month/YYYY Professor/Dr: Topic title: Synaptic Communication: Integration of EPSP’s & IPSP’s EPSP: excitatory postsynaptic potential. IPSP: inhibitory postsynaptic potential. DD/Month/YYYY Professor/Dr: Topic title:  Excitatory Post-Synaptic Potential EPSPs are graded. Presynaptic Amplitude depends on: amount of NT released. number of receptors. state of receptors Postsynaptic Decay depends on: dissociation of ligand. diffusion and uptake (e.g. glutamate). Can also depend on: Axon Initial desensitization (e.g. AMPA-type glu Segment receptors). No AP AP enzymatic breakdown (e.g. Ach). Professor/Dr: DD/Month/YYYY Topic title: Spatial Summation of EPSP’s Professor/Dr: DD/Month/YYYY Topic title: Temporal Summation of EPSP’s Professor/Dr: DD/Month/YYYY Topic title: Temporal Summation of EPSP’s Professor/Dr: DD/Month/YYYY Topic title: EPSPs & IPSPs EPSPs and IPSPs are sub threshold events which determine whether a neuron or muscle (end-plate potential) will reach a threshold to fire an action potential. EPSPs sum to generated depolarisation (more likely to fire an action potential). IPSPs sum to generate hyperpolarisation (less likely to fire an action potential). Given that a neuron has approximately 10,000 synapses, the potential to fire an action potential is based on the balance of EPSPs and IPSps which act to cancel each other out. DD/Month/YYYY Professor/Dr: Topic title: Synaptic Modulation  +   1. An excitatory neuron fires. 2. An AP is generated. 3. Signal is passed on to all targets. 4. Postsynaptic response elicited. DD/Month/YYYY Professor/Dr: Topic title: Synaptic Modulation: Presynaptic Inhibition _ X +   1. An excitatory neuron fires. 2. An AP is generated. 3. An Inhibitory neuron fires blocking NT release at 1 synapse. 4. Postsynaptic response elicited in 2 of 3 targets. DD/Month/YYYY Professor/Dr: Topic title: Synaptic Modulation: Postsynaptic Inhibition _ X + X X 1. An excitatory and an inhibitory neuron fire. 2. The excitatory and inhibitory postsynaptic potentials result in a below threshold graded potential. 3. No AP is generated. 4. No response elicited in any target. DD/Month/YYYY Professor/Dr: Topic title: Synaptic Modulation Presynaptic inhibition. More specific control. Precise inhibition of specific synapses. Postsynaptic inhibition. General inhibition. All synapses inhibited equally. DD/Month/YYYY Professor/Dr: Topic title:  Neural Networks Someone is talking I just got a text message Its about action potentials Professor/Dr: DD/Month/YYYY Topic title: Simple Neural Networks Brain (complex processing) upper motor neuron dorsal root/trigeminal ganglion secondary Generator Potentials afferent primary afferent Sensory terminals in skin lower motor neuron DD/Month/YYYY Professor/Dr: Topic title: muscle The Knee Jerk Reflex: Communicating Across Networks DD/Month/YYYY Professor/Dr: Topic title: Surround/Lateral Inhibition DD/Month/YYYY Professor/Dr: Topic title: Recurrent Inhibition Descending influences α motor neuron Muscle Renshaw cell DD/Month/YYYY Professor/Dr: Topic title: Building Networks Feedforward excitation Lateral inhibition Feedback excitation Feedforward inhibition Feedback inhibition Convergence/Divergence Recurrent excitation Recurrent inhibition Professor/Dr: DD/Month/YYYY Topic title: [email protected] Feel free to contact me with any questions about these lectures or any interest you may have in neuronal signalling and pain/migraine. DD/Month/YYYY Professor/Dr: Topic title: