Presentation is loading. Please wait.

Presentation is loading. Please wait.

Signal processing in neurons

Published byJulie Norris Modified over 8 years ago

Similar presentations

Presentation on theme: "Signal processing in neurons"— Presentation transcript:

1 Signal processing in neurons
Metabotropic neurotransmission Electrical signals in dendrites Active properties of dendrites Signal processing at the Synapse (post) Dendrite Soma Synapse (pre)

2 Neuronal Anatomy Dendrites Cell Body/Soma Axon Input-spine
Output-bouton

3 Neural circuits, cartoon version
Spindle afferents excite the homonymous motor neuron and inhibit antagonists MNa Agonist Ia Antagonist MNb IN Inhibitory synapse Excitatory synapse

4 Synaptic structure Garner 2002

5 Modulation of Input E/I PSPs
Synaptic strength (fast) Efficiency of neurotransmitter release Area/receptor number Channel conductance/sensitivity Dendrite morphology (slow) Input resistance Membrane capacitance Electrical propagation

6 NMDA receptor mediated plasticity
Glutamineric synapses have both AMPA and NMDA receptors Long term potentiation: Tetanus increases subsequent EPSPs Tetanic depolarization relieves Mg2+ block (NMDA) Calcium induced channel phosphorylation increases conductance Long term potentiation Ca2+ influx via NMDA receptors DepolNMDACa2+CaMKIIAMPA Ca2+(PKA)-|I1->PP1-|AMPA High frequency stimulation High Calcium I1 is inhibited Reduces PP1 Increases AMPA

7 Metabotropic neurotransmission
GPCRs Gs Adenyl Cyclase AC->PKA->channel phos (NaV) Gq phospholipase C PLC->DAG->PKC->channel phos (AMPA) Gbg GirK G-coupled inward rectifying potassium channel Gbg CaV N, P, Q type voltage gated calcium channel Slow – seconds to minutes

8 Girk Hippocampal neurons GABAA channel GABAB GPCR
1300 pA Cl- current GABAB GPCR 50 pA K+ current Slow kinetics Different GABA sensitivity Cooperative currents different time Picrotoxin blocks GABAA Ba2+ blocks K+ GABAA GABAB Distinct I-V curves Different reversal potentials Sodickson & Bean 1996

9 Metabotropic Neuromodulation
DSI stimulation triggers fast and slow depolarization Slow depolarization is GTP dependent Blocked by non-exchangeable GDP-b-S Fast Ionotropic depolarization Stimulation Recording Slow metabotropic depolarization Blocks metabotropic process

10 mGluR1 suppression of m-current
M-Current: potassium current, near threshold, helps set excitability After-hyperpolarization EPSPs recorded in CA3 neurons of guinnea pig DHPG is an mGluR agonist Brief exposure Long exposure Prolonged exposure to DHPG results in sustained inactivation of m-current Sustained, but not immediate suppression requires p38 MAP kinase Young S R et al. J Neurophysiol 2008;99:

11 Dendrite Morphology Multiple synapses (10k+) Multiple morphologies
Post-synaptic density VI Popov et al., 2004 Neuroscience

12 Electrical interaction in dendrites
Local depolarization propagates Internal resistance Membrane capacitance Time constants RC Signal attenuation Leak current Extracellular Rm Cm Rm Cm Ri Intracellular

13 Active properties of dendrites
NaV Low density prevents AP PSP regeneration, amplification CaV T-type, low threshold “Window current” bistatility Additional calcium-mediated magic Ih Slow depolarization Pacemaker

14 Multiple inputs Consider Unitary PSP 5 mV Simultaneous PSP
Input current ~ 750pA = GV = G(0.060-(-0.060) G=6250 pS (multiple channels at one synapse) Simultaneous PSP G=12,100pS Input current 1500 pA Second PSP during coincident wave: G=6250; V=(0.06-(-0.055))= 115 mV Input current = 720 pA Dendritic branches isolate circuits

15 Coincidence reinforcement
“Hebbian” plasticity Neurons that fire together, wire together Reinforcement of synapse consequent to AP Back-propagation of AP, faster than PSP Stuart & Hauser, 2001

16 Current interactions Kleak KNa Ih (Nah) NMDA LVA (CaT) NaV HVA (CaL) Kir KCa Cl Multiple ions, multiple gatings Local to synapse or distributed Experimental models are incomplete: Intact, decerebrate, isolated spine, slice, culture Unique populations of neurons See Grillner (2003); construct potential in a CPG or motor neuron w/nifedipine, stychnine, etc

17 Axon hillock Integrates signals across dendritic tree
Dense NaV, highest probability of AP Rheobase Chronaxie . 2 4 6 8 1.0 1 3 5 Stim Duration (ms) Stim Ampl (nA) Action Potential No Action Rheobase 2x Rheobase Chronaxie

18 Output Action Potential
Presynaptic inhibition Ionotropic Sub threshold depolarization of bouton Reduce Ca2+ influx Metabotropic mGluR group II & IIII Local NT release feeds back on presynaptic neruon

19 Sea slug (tritonia) locomotion
Characteristic escape response Alternate, vigorous body flexion Simple neural circuit Lawrence & Watson 2002

20 Intracellular potential
Tritonia CPG Escape is a programmed response Katz, et al., 2004 Dorsal Swim Interneuron Ventral Swim Interneuron Ventral Flexion Neuron Dorsal Flexion Neuron Flex Extend Intracellular potential of neurons Stimulate sensory neurons to elicit escape

21 Tritonia Metabotropic Neuromodulation
DSI stimulation triggers fast and slow depolarization Slow depolarization is GTP dependent Blocked by non-exchangeable GDP-b-S Fast Ionotropic depolarization Stimulation Recording Slow metabotropic depolarization Blocks metabotropic process

Download ppt "Signal processing in neurons"

Similar presentations

Topic 6.5 - Nerves.

Topic Nerves.
Neural Signaling: Postsynaptic Potentials Lesson 9.

Neural Signaling: Postsynaptic Potentials Lesson 9.
Ligand gated ion channels Channel structure –Heteropentamer –4-transmembrane pass subunits Neurotransmitter diversity Post synaptic potentials –Excitatory.

Ligand gated ion channels Channel structure –Heteropentamer –4-transmembrane pass subunits Neurotransmitter diversity Post synaptic potentials –Excitatory.
Neuro I Or: What makes me do that Voodoo that I Do so Well!

Neuro I Or: What makes me do that Voodoo that I Do so Well!
LECTURE 9: INTEGRATION OF SYNAPTIC INPUTS (Ionotropic Receptors) REQUIRED READING: Kandel text, Chapter 12 At neuromuscular synapse, single axonal action.

LECTURE 9: INTEGRATION OF SYNAPTIC INPUTS (Ionotropic Receptors) REQUIRED READING: Kandel text, Chapter 12 At neuromuscular synapse, single axonal action.
Neurophysiology. The Resting Membrane Potential Intracellular (soma) Extracellular VV -70 mV.

Neurophysiology. The Resting Membrane Potential Intracellular (soma) Extracellular VV -70 mV.
Part Fundamentals of Physiology Part II Food, Energy, and Temperature Part III Integrating systems Part IV Movement and Muscle Part V Oxygen, Carbon dioxide,

Part Fundamentals of Physiology Part II Food, Energy, and Temperature Part III Integrating systems Part IV Movement and Muscle Part V Oxygen, Carbon dioxide,
4-1 3. Transmission across synapses a. Depolarization of presynaptic cell b. Increase in inward gCa ++ via voltage gated Ca ++ channels c. Vesicle migration.

Transmission across synapses a. Depolarization of presynaptic cell b. Increase in inward gCa ++ via voltage gated Ca ++ channels c. Vesicle migration.
Cellular Neuroscience (207) Ian Parker Lecture #13 – Postsynaptic excitation and inhibition.

Cellular Neuroscience (207) Ian Parker Lecture #13 – Postsynaptic excitation and inhibition.
SPPA 2050 Speech Anatomy & Physiology 1 Neuronal Function Goal: electrochemical communication Requirement: Electrochemical signal generation Electrochemical.

SPPA 2050 Speech Anatomy & Physiology 1 Neuronal Function Goal: electrochemical communication Requirement: Electrochemical signal generation Electrochemical.
Effects of Excitatory and Inhibitory Potentials on Action Potentials Amelia Lindgren.

Effects of Excitatory and Inhibitory Potentials on Action Potentials Amelia Lindgren.
Inhibitory and Excitatory Signals

Inhibitory and Excitatory Signals
By Eamon Quick. The Rundown Long-Term Potentiation (LTP): activity-dependent increase in synaptic activity –Dependent upon NMDA receptor activation Favors.

By Eamon Quick. The Rundown Long-Term Potentiation (LTP): activity-dependent increase in synaptic activity –Dependent upon NMDA receptor activation Favors.
Long term potentiation (LTP) of an excitatory synaptic inputs is input specific.

Long term potentiation (LTP) of an excitatory synaptic inputs is input specific.
The Integrate and Fire Model Gerstner & Kistler – Figure 4.1 RC circuit Threshold Spike.

The Integrate and Fire Model Gerstner & Kistler – Figure 4.1 RC circuit Threshold Spike.
sensory receptor sensory input integration motor input effector.

sensory receptor sensory input integration motor input effector.
1 Session 5 The Neuron II: Synaptic Transmission PS111: Brain & Behaviour Module 1: Psychobiology.

1 Session 5 The Neuron II: Synaptic Transmission PS111: Brain & Behaviour Module 1: Psychobiology.
Nervous systems. Keywords (reading p. 960-976) Nervous system functions Structure of a neuron Sensory, motor, inter- neurons Membrane potential Sodium.

Nervous systems. Keywords (reading p ) Nervous system functions Structure of a neuron Sensory, motor, inter- neurons Membrane potential Sodium.
Neural Plasticity Lecture 7. Neural Plasticity n Nervous System is malleable l learning occurs n Structural changes l increased dendritic branching l.

Neural Plasticity Lecture 7. Neural Plasticity n Nervous System is malleable l learning occurs n Structural changes l increased dendritic branching l.
Synapses A. Neuromuscular Junction (typical ACh synapse) 1. arrival of action potential at terminal bulb triggers opening of voltage-gated Ca ++ channels.

Synapses A. Neuromuscular Junction (typical ACh synapse) 1. arrival of action potential at terminal bulb triggers opening of voltage-gated Ca ++ channels.

Similar presentations

Ads by Google