The amygdala modulates prefrontal cortex activity

relative to conditioned fear

Rene Garcla , Rose-Marie Vouimba , Michel Baudry, Richard F. Thompson

Nature 402,294-296(1999)

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

Prefrontal Cortex(PFC)

•The PFC connects with a vast array of other cerebral structures and itself.• The PFC is dedicated to the emotional behavior, memory, planning, execution of actions and temporal organization of behavior.

Amygdala( 杏仁核 )

•The amygdala connect the region concerned with somatic expression of emotion and the neocortical area concerned with conscious feeling, especially fear.

• Animals trained in classical conditioning display fear responses, freezing, when they hear the conditioned tone.

• Freezing to a conditioned tone is enhanced following damage to the dorsal part of mPFC.

• Amygdala is required for both the acquisition and expression of learned fear responses(freezing).

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

•Whether the changes(depression) of PFC neurons activity is related to the freezing behavior?

•If the damage of amygdala can abolish the changes(depression) of PFC neurons activity?

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

• 36 male mice

(C57BL/6 JI; 4-6 months; 28-32g)• Electrodes were made of platinum-iridium wires(5

0μm in diameter), and were positioned in the PFC for recording and in the amygdala for lesion respectively.

• The behavior of mice was observed using a video camera monitor system.

Neuron activity

freezing

A: spikes during CI or CSB: spikes during pre-CI-CS period

(B-A)/(B+A)

A: spikes during CI or CSB: spikes during pre-CI-CS period

(B-A)/(B+A)

• The changes of PFC neurons activity is related to the freezing behavior.

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

• Tone-shock association• Lesion(4 types)• Auditory test(CS only)• Amygdala form one side project poorly to the

contralateral side

PFC

Amygdala

• The depression in PFC neuron activity is modulated by amygdala, not the freezing response.

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

• The changes of PFC neurons activity is related to the freezing behavior.

• The depression in PFC neuron activity is modulated by amygdala, not the freezing response.

Introduction

Question

Experiment 1

Experiment 2

Result

Discussion

• 為什麼要用 conditioned freezing(fear) 當作研究 emotion的題材

1. 這是一種比較極端強烈的情緒反應 , 比較容易觀察 2. 這是一種生存上必需的反應 , 以躲避危險的事物 , 所

以可以在較低等的生物上看到• Amygdala 會影響 PFC 的 activity, 可能是為了在緊急的

時候 , 先關掉 PFC 的 decision-making 的功能• Amygdala 可以控制 PFC 的 activity, 但是否會經過其他

的路徑 , 而不是直接地控制 ?

• 為何在選取 electrical activity 時 ,signal to noise ratio 必須要超過 4 比 1?