I. Basics Electrophysiology is the study of cell electrical activity resulting from ion channel...
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Transcript of I. Basics Electrophysiology is the study of cell electrical activity resulting from ion channel...
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