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I. Basics
Electrophysiology is the study of cell electrical
activity resulting from ion channel function.
Electrolyte composition of the cell
Na+: 5-10 mMK+: 110-145 mMCa2+: 100 nMCl-: 5-50 mM
Na+: 145 mMK+: 5-10 mMCa2+: 2 mMCl-
: 145 mM
OUT ION CHANNELS
Voltage-gated Ligand-gated
} Glu, Ach
♦ GABA
IN
Fundamental laws
Nernst's equation: Er = RT/F ln [Co/Ci]
Driving force = Em - Er
Ohm's law: V = R x I
A simplified view of cell-cell communication
Ligand-gated channels code for input
……...….
Neurotransmitter(s)
VG channels
Voltage-gated channels code for output
Baseline
Na leak
GABAA IPSPs
GABAB IPSP
Baseline
Subthreshold AMPA EPSP
Threshold AMPA EPSP
NMDA EPSP
NMDA + GABAA PSPs
II. MethodsSystems level (106+cells)
- EEG, evoked potentials
Nuclear (ensemble) level (102-103+ cells)- Population spike
Single-unit (extracellular) recording (1-3 cells)- In vivo microiontophoresis
Cell level- Intracellular recording- Patch-clamp (whole-cell recording)
Subcellular level- Patch-clamp (single-channel recording)
Cellular electrophysiology
Selective antagonism of GABA responses in the cuneate nucleus of the
anesthetized rat
Configurations of the patch-clamp technique
Configurations of the patch-clamp technique
Patch-clamp dates
⟨ 1976: First patch-clamp recording (first time ion channels wereobserved!)Neher and Sakmann, Nature 260:799
⟨ 1981: Comprehensive account of patch-clamp methods publishedHamill et al., Pflügers Arch 391:85
⟨ 1989: Methods for patch-clamp in slices publishedEdwards et al., Pflügers Arch 414:600
⟨ 1991: Nobel prize awarded to Neher and Sakmann⟨ 1993: Infra-red differential interference contrast (IR-DIC) methods
publishedStuart et al., Pflügers Arch 423:511
The voltage-clamp technique
III. From channels to behavior
The thalamocortical augmented response (AR)
Circuits involved in the AR
Cellular mechanism of the AR
Behavioral component of the AR