The amygdala part of the limbic system doesn’t process beliefs

Does your desk light switch on or off when other people in the office switch their desk lights on or off? Something in the wiring would probably be wrong if it did.

And wouldn’t you expect that other desk lights would still operate normally if your desk light’s bulb burned out, although everyone may be plugged into the same electrical circuit?


It surprised the researchers of this 2015 CalTech/MIT study when:

“Two patients with bilateral amygdala lesions performed a belief reasoning test.

Both patients showed typical test performance and cortical activity when compared with nearly 500 healthy controls.”

The study’s overall frame of reference was expressed as:

“Humans use a so-called “theory-of-mind” to reason about the beliefs of others. Neuroimaging studies of belief reasoning suggest it activates a specific cortical network. The amygdala is interconnected with this network and plays a fundamental role in social behavior.”

The experimental test:

“Was designed to optimize functional contrast in those brain regions thought to be involved in attempts, be they successful or unsuccessful, to evaluate the veracity of another person’s belief about the world.”


A “belief reasoning test..to reason about the beliefs of others” is a cerebral exercise. The amygdala, in contrast, is an emotional center of a person’s limbic system.

The logic by which the study may be viewed is:

  1. The “belief reasoning test” had no emotional content to activate the subjects’ amygdalae.
  2. fMRI scans confirmed that limbic system areas in the 2 lesioned subjects weren’t activated during the test.
  3. Apply the logic of Occam’s razor, and we arrive at the findings of “typical test performance and cortical activity.”

Task performance and beliefs about task responses are solely cerebral exercises had a similar methodology and result in that those subjects’ limbic systems were monitored during fMRI scans and subsequent reporting, but the subjects’ limbic system areas weren’t activated during any of the experiments.


The researchers stated the results:

“Suggest a reevaluation of the role of the amygdala and its cortical interactions in human social cognition.”

But per the beginning analogy – if your desk light’s bulb burned out, would you be surprised that it didn’t affect the normal operations of desk lights in other offices, although they all may be plugged into the same circuit?

This study informed us that the amygdala isn’t slaved to the cerebrum. It’s hard to change the current research mindset/social meme of cerebral dominance, though, so maybe this information will be overlooked.

http://www.pnas.org/content/112/15/4827.full “Amygdala lesions do not compromise the cortical network for false-belief reasoning”

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