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How the Brain ‘Constructs’ the Outside World

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How the Brain ‘Constructs’ the Outside World

Neural activity probes your physical surroundings to select just the information needed to survive and flourish

Scientific American,

5 min read
4 take-aways
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What's inside?

The brain perceives and responds to the world from the “inside-out.”

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Neuroscience assumed for decades that the brain starts as a “blank slate” onto which experience “paints” itself, thus becoming more complex over time. In fact, the brain is far more concerned with its own internal dynamics than with simply processing external stimuli, suggesting a more robust “inside-out” model for perception. Systems neuroscientist György Buzsáki’s experiments with rats reveal that neural activity is a constant interplay between internal processes and external stimulation. Cognition’s core lies in how the brain connects new experiences to foundational knowledge.


The “outside-in” model isn’t sufficient to explain how the brain processes stimuli.

Philosophers going back to Ancient Greece endorsed the tabula rasa concept to describe human cognition. This blank slate inside the skull is painted by experience. This concept persisted for millennia, even permeating neuroscience and psychology. This is why, for decades, neuroscience has labored under the misapprehension that cognitive processes originate with external inputs. These inputs are then sent to a “central processor” for interpretation.

While convenient and easy to explain in principle, this “outside-in” model has a serious flaw: No one knows where that processor resides, or exactly what it does with those inputs. It also assumes that neurons automatically turn simple patterns into complex ones and devise a meaning. But the central processor has eluded science. Was it free will? A homunculus? Executive function? Or just a “black box”? This approach cannot, for instance, explain how light falling on a flower brings to mind a memory of a summer day. The outside-in model can’t be the whole story.


About the Author

György Buzsáki is a systems neuroscientist whose work has focused on the ways memories form and how brain rhythms segment neural information to support cognition. He was a co-recipient of the 2011 Brain Prize from the Lundbeck Foundation. Buzsáki is the author most recently of The Brain from Inside Out.

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