Learning to Fear Flashcards
(42 cards)
Fear
a conscious experience, behavioral and physiological changes in the brain, subjective feelings
highly adaptive and fundamental to survival
3 different dimensions of conditioned responses
autonomic, endocrine, behavioral
Unconditioned response - misconception
what is innately evoked
for the rats being shocked, it is the startle, not the freeze
Unpaired group
same number of tone and shock presentations, but not paired together
Is pairing sufficient for learning?
No - CS must be informative
shown through experiments or blocking and probability of shock
Blocking (is pairing sufficient for learning experiment)
Pairing tone and light is not enough to learn about the light
Probability of Shock (is pairing sufficient for learning experiment)
probability of the shock has to be higher during the CS
Context fear learning
A novel environment can act as a CS during training
Differentiating between context and cued learning (2 options)
1) test for CRs to both the context alone, and to the cue in a different context
2) Measure responding during the test session prior to CS
CS responding – pre-CS responding = elevation score
Immediate shock deficit
Rats that are shocked immediately after being placed in a context
Unable to form an integrated representation of the space to associate with the shock
How we overcome immediate shock deficit
Prior exposure to the context alleviates the deficit
Does immediate shock deficit relate to discrete cues
A discrete cue CS (like a tone) can be paired simultaneously with the US and learning will occur
Persistence of a conditioned fear
Both context and cued fear conditioning last a lifetime (in rats)
What is the amygdala
Emotional salience
Basolateral Area (BLA)
Central Amygdala (CeA)
Where is the amygdala
Located deep within the temporal lobe
How did we first start to associate the amygdala with fear?
Kluver-Bucy syndrome - Bilateral temporal lobectomy
- hyperorality, hypersexuality, psychic blindness, placidity - no fear in fearful situations
What is Ledoux’s early model of the amygdala and fear learning?
thalamus and cortexes send info to the LA
The BLA is the sight where the association forms
LA sends info to the CE
CE controls output of learning-> the coordinated fear response
What happens to fear learning if we interfere with the amygdala?
Temporary inactivation of the BLA prior to training prevented fear learning to the CS
What happens to fear expression if we interfere with the amygdala?
Temporary inactivation of the BLA prior to testing prevented the expression of previously acquired learned fear
Both recently and remotely acquired fears were affected
What is the difference between electrolytic and excitotoxic lesions?
Electrolytic - high frequency electric current through an electrode
Excitotoxic - micro infusion of a neurotoxin through a cannula
Temporary inactivation
Through cannula infusion systems
- local anesthetic, GABA agonist, NA channel blocker
Optogenetics
activating the specific population of LA neurons that were active during fear conditioning produces robust freezing behavior
What happens when you remove BLA function?
- prevent acquisition of fear learning
- prevent expression of fear learning
BLA is necessary for:
- acquisition
- expression
- storage
of conditioned fear
