BBio 351 – February 29, 2016 Outline for today Spread of signals within and between neurons Passive and active spread (Sherwood ) Synapses (Sherwood ) Neurotransmitters & PSPs (Sherwood 4.7) Neurons compute things! Computation by individual post-synaptic neurons Computation by neural circuits

Synapses: 2 types CSLS/University of Tokyo

Chemic al synapse s Sherwood Figure 4-16 Ca 2+ Vesicles Neurotransmitter Receptors

Post-synaptic cells EPSPs and IPSPs Temporal & spatial summation at the axon hillock. Threshold reached? Action potential? Sherwood Figure 4-15 See Fig. 4-16

Neurotransmitters, ligand-gated channels, & PSPs Example: acetylcholine (ACh)

Neurotransmitters, ligand-gated channels, & PSPs Example: acetylcholine (ACh) F.H. Martini et al. (2014), Fig

Neurotransmitters, ligand-gated channels, & PSPs Example: acetylcholine (ACh) F.H. Martini et al. (2014), Fig

Neurotransmitters, ligand-gated channels, & PSPs NeurotransmitterReceptor/ channel opened Typical E ion Direction of ion flow EPSP or IPSP AcetylcholineCation (mostly Na + ) E Na = +55 mV GlutamateCation (mostly Na + ) Gamma-aminobutyric acid (GABA) GABA A : Cl - GABA B : K + E Cl = -70 mV E K = -90 mV GlycineCl - Dopamine5 receptors (D 1 to D 5 ) Serotonin7 receptor families (5- HT 1 to 5-HT 7 ) for V m = -60 mV

Altering synaptic transmission Alter release of neurotransmitter Ethanol => GABA release (see figure below) Alter presynaptic reuptake of neurotransmitter Cocaine => dopamine reuptake SSRIs: serotonin-specific reuptake inhibitors Criswell & Breese, Neuropsychopharmacology 2005 No Ethanol With Ethanol CH 3 CH 2 OH

How computers work (sort of) What is a bit? What can be done with bits? Figures: AllAboutCircuits.com

How computers work (sort of) electronics.stackexchange.com

Computation by individual post-synaptic neurons Sherwood Figure 4-15 See Fig Are the inputs (EPSPs and IPSPs) binary?

nba.uth.tmc.edu/neuroscience/s1/introduction.html

Computation by a post-synaptic neuron: an example Draw/explain why a post-synaptic neuron O (for output) might fire if and only if pre-synaptic neurons A, B, and C are all active simultaneously. Why might these sorts of output neurons be useful to animals?

Neurons are arranged in CIRCUITS nba.uth.tmc.edu/neuroscience/s1/introduction.html

Computations by neural circuits: fever! (resetting setpoint) neuroscience.uth.tmc.edu/s4/chapter03.html

Computations by neural circuits: fever! (resetting setpoint)

Computations by neural circuits: lateral inhibition Purpose/Goal: improve detection of EDGES of objects. Figures on following slides were taken from the introductory chapter ( of Neuroscience Online (