• Electrophysiology fundamentals
• Types of Patch clamp recordings
• Patch clamp procedures
• A glimpse of electrophysiological data visualization

What is Electrophysiology ?
Fundamentals Types Procedures Visualization
• The study of the electrical properties of biological cells and tissues.
• Voltage change or electric current
On a wide variety of scales, from single ion channels to whole organs

Nature of neuronal electricity
Fundamentals Types Procedures Visualization
Neuron: a enclosed lipid membrane envelope, Lipid layer has a high resistance.
Ion channels, pumps in the membrane
Voltage difference across the membrane.
Selective permeability to ions.

Nature of neuronal electricity
Electrical equivalent circuit
Fundamentals Types Procedures Visualization
R in
C m
Circuits & Brain: organized complexes consisting of this electric unit.

Mission of Electrophysiology
Fundamentals Types Procedures Visualization
• Measurements of electrical activity of neurons, particularly synaptic and action potential
(AP) activities.

Methods of Electrophysiology
Fundamentals Types Procedures Visualization
• Extracellular recording
EEG (electroencephalogram), LFP (Local field potential ), Single-unit ( SU ), Multi-unit (MU)
• Intracellular recording
• Patch-clamp recording

各种电生理记录的优缺点：
细胞外记录
记录群体或单细胞的电活动；
容易得到信号，机械稳定性要求低。
电极粗大，对组织损伤大。
细胞内记录
记录单个神经元，电位变化精确可控，可进行
电压钳、电流钳实验。对细胞内过程影响小。
只能记录细胞胞体，机械稳定性要求高。
全细胞记录
记录单个神经元，电位变化精确可控，可进行
电压钳、电流钳实验，对亚细胞结构进行记录。
机械稳定性要求低。
对细胞内过程影响大（除穿孔全细胞记录）。

Resting membrane potential
Vm = Vin – Vout
Fundamentals Types Procedures Visualization
(Vout = Vfar ∞ = 0mV)
Electrical potential Vs. Concentration gradient

Resting membrane potential
Fundamentals Types Procedures Visualization
R: 气体常数 ; T: 绝对温度 ; F: 法拉第常数 ; z: 离子电荷数

Resting membrane potential
Fundamentals Types Procedures Visualization

Resting membrane potential
Fundamentals Types Procedures Visualization

Equivalent circuit
Fundamentals Types Procedures Visualization

Hardware
Amplifier
DAC

Hardware
• Patch-clamp system
Stimulus controller
Fundamentals Types Procedures Visualization
Monitor
/oscillograph
Amplifier
Digital/Analog signal converter
(DAC) pipette
Neuron
Signal collection and procession platform
(interface)

减法运算器 I f
=(V p
-V o
)/R f
V
P
V
P V
P
Fundamentals Types Procedures Visualization
Voltage Clamp: 运算放大器

Current Clamp:
电压跟随器
（也是运算放大器的一种）
Fundamentals Types Procedures Visualization
加法运算器
17

Hardware : patch clamp amplifier
• Axon
Axoclamp 2 系列： Axoclamp 2B （已停产）
Axopatch1 系列： Axopatch 1D （已停产）
Axopatch 200 系列： Axopatch 200B
GeneClamp500 ： GeneClamp500B （已停产）
MultiClamp 700 系列： MultiClamp 700B
⁻ two headstages
⁻ software control on PC: Commander
⁻ Voltage & current clamp
Axoclamp 900A
Fundamentals Types Procedures Visualization
• HEKA

Software: Commander panel
Fundamentals Types Procedures Visualization

Methods of Electrophysiology
• Patch-clamp recording
Fundamentals Types Procedures Visualization
4 kinds of patch clamp
(A)cell-attached
(B) whole-cell
(C)outside-out
(D)inside-out http://www.bem.fi/book/04/04x/0427x.ht
m

Methods of Electrophysiology
Fundamentals Types Procedures Visualization
Use Advantages Major Disadvantage
Cell-attached
Single-channel recording
Physiological conditions
Easy to obtain
Unknown membrane potential; No superfusion
Inside-out
Single-channel recording
Cytosolic superfusion
Extracellular control
Not easy to obtain
Outside-out
Single-channel recording
Extracellular superfusion
Cytosolic control
Missing essential internal substance
Whole-cell
Perforated
Macro-current recording
Extracellular superfusion
Cytosolic control
Disrupt cytoplasmic contents
Macro-current recording
Extracellular superfusion
No washout
Not easy to obtain

Glass pipette
• Sharp electrode
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• Patch-Clamp pipette

Breaking target cell
Fundamentals Types Procedures Visualization

Intracellular solution Dye loading
Fundamentals Types Procedures Visualization
Morphological characterization: Alexa 488 594 Lucifer yellow

Voltage clamp
• Ion channel properties, Current changes
⁻ Sodium Current
Fundamentals Types Procedures Visualization
Inactivation curve
慢门
Activation curve
快门
Li et al. (2014). PLoS Biol

Voltage clamp
• Ion channel properties, Current changes
⁻ Postsynaptic currents
Fundamentals Types Procedures Visualization eEPSC eIPSC
I-V curve
50
-80
-120 mV
40
0
-40
25 pA
0.1 s
-100 -50
-50
-100
I (pA)

Current clamp
• Threshold analysis
⁻ PV & SST cells
Fundamentals Types Procedures Visualization
Li et al. (2014). PLoS Biol

Current clamp
• Voltage changes, physiological functions
Fundamentals Types Procedures Visualization
I-V curve RF
60
40
10 mV
0.5 s
20
0
-20 0 20
Current injection (pA)
-50
-60
40 mV
0.4 s
RF
-35
-40
-45
-50
-55
0 5 10
Time ( s )

Current clamp
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• Brain/ network state: Vm characteristics depend on network state
⁻ synchronous & asynchronous states
Tan et al. (2014). Nature

Current clamp
• Brain/ network state:
⁻ Vm skewness
Fundamentals Types Procedures Visualization
⁻ Whole-cell Vm measurements from V1 of behaving monkeys
Tan et al. (2014). Nature

Current clamp
• Brain/ network state: Vm fluctuations
Fundamentals Types Procedures Visualization
⁻ Whole-cell Vm measurements from V1 of behaving monkeys
Tan et al. (2014). Nature

Current clamp
Fundamentals Types Procedures Visualization
• Brain/ network state: Vm & LFP relationship
Tan et al. (2014). Nature

Current clamp
Fundamentals Types Procedures Visualization
• Analog mode of excitatory synaptic transmission disynaptic IPSPs
Zhu et al. (2011). PLoS Biol

Current clamp
Fundamentals Types Procedures Visualization
• Analog mode of excitatory synaptic transmission
Zhu et al. (2011). PLoS Biol
EPSP summation window

Current clamp
Fundamentals Types Procedures Visualization
• Analog transmission: mediated by SST but not PV interneurons
Zhu et al. (2011). PLoS Biol

• Electrophysiology fundamentals
• Types of Patch clamp recordings
• Patch clamp procedures
• A glimpse of electrophysiological data visualization
⁻ Versatile interpretation & presentation according to specific questions/studies

Q & A