Nucleus · one in each half of the brain
Basolateral amygdala
Also called BLA, Lateral, basal and accessory basal nuclei
The amygdala's learning hub: works out what is dangerous and what is rewarding.
The basolateral complex is the amygdala's main input side. It gathers information from most of the senses and from memory areas, and learns which things predict danger or reward. If a harmless sound keeps coming just before something painful, this is where the link between the two is thought to form. It then passes its verdict to the centromedial nuclei, which set off the body's response.
Where it is
The lower, outer part of each amygdala, deep in the front of the temporal lobe.
What it does
Gathering the senses
It receives sights, sounds, touch, taste and more, both from the thalamus and from the cortex.
Learning danger
It links neutral things, like a sound or a place, with bad outcomes. Scientists call this fear conditioning.
Learning reward
It also links cues with good outcomes, helping you want things that have been rewarding before.
Strengthening memories
When stress hormones are released, it helps the hippocampus store emotional events more strongly.
Sending the verdict
It passes its judgment to the centromedial nuclei, which turn it into a body response.
Think of it as a detective who studies every incoming clue and decides, "that sound means trouble" or "that smell means dinner".
Works with
- Centromedial amygdalaIt sends its "danger" or "safe" verdict to the centromedial nuclei, which launch the body's response.
- HippocampusIt swaps information with the hippocampus, adding emotional weight to memories and learning which places are dangerous.
- Prefrontal cortexIt works in a two-way loop with the prefrontal cortex, which can learn that a feared thing is now safe and quiet it down.
- Medial geniculate nucleusIn animal studies, sounds reach it directly from the medial geniculate nucleus, the thalamus's hearing relay, which lets it learn to fear a sound very quickly.
- Nucleus accumbensIt tells the nucleus accumbens which cues predict reward, helping to drive the urge to go after them.
- Pyramidal neuronIts main neurons look a lot like the pyramidal neurons of the cortex, which makes this part of the amygdala unusually cortex-like.
When it goes wrong
Phobias and PTSD
Overly strong fear links, for example between a place and a past trauma, are thought to be stored here. Exposure therapy works by building new "this is safe" memories, rather than erasing the old one.
Cravings and relapse
Animal studies show it helps cues linked to drugs, like a place or a smell, set off strong cravings, which can lead to relapse.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- Fear learning here is fast: in rats, a few pairings of a sound with a mild shock can be enough to create a lasting fear of the sound. Learning quickly what predicts danger helps animals survive.
- Fear memories are very hard to erase. When a fear fades with therapy, the old memory is usually still there, just held in check, which is why fears can sometimes come back.
Where the name comes from
"Baso" refers to the base, or bottom, and "lateral" means toward the side. The name describes where these nuclei sit: in the lower, outer part of the amygdala.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the basolateral complex?
Show the answer
Gathering the senses. It receives sights, sounds, touch, taste and more, both from the thalamus and from the cortex.
Gathering the senses. It receives sights, sounds, touch, taste and more, both from the thalamus and from the cortex.
The basolateral complex is part of which larger structure?
Show the answer
Amygdala. It belongs to the amygdala.
Amygdala. It belongs to the amygdala.
Which part fits this description? "Like a detective who studies every incoming clue and decides, "that sound means trouble" or "that smell means dinner"."
Show the answer
Basolateral complex. It is the basolateral complex. The amygdala's learning hub: works out what is dangerous and what is rewarding.
Basolateral complex. It is the basolateral complex. The amygdala's learning hub: works out what is dangerous and what is rewarding.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Amygdala, StatPearls, NCBI Bookshelf
- 13.3 What Is the Contribution of Brain Structures in Emotional States?, OpenStax, Introduction to Behavioral Neuroscience
- 8.2 Parts of the Brain Involved with Memory, OpenStax, Psychology 2e
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