Rapid Encoding of New Memories by Individual Neurons in the Human Brain

Matias J. Ison, Rodrigo Quian Quiroga, Itzhak Fried
Neuron  2015  87:220-230
© The Author(s). 2015
Published: 01 July 2015

• Contextual associations were used to model the formation of new memories
• Human single neurons changed their firing patterns to encode new associations
• Changes occurred at the exact moment of learning, even after single presentations
• The rapid speed of neural changes is compatible with episodic memory formation

The creation of memories about real-life episodes requires rapid neuronal changes that may appear after a single occurrence of an event. How is such demand met by neurons in the medial temporal lobe (MTL), which plays a fundamental role in episodic memory formation? We recorded the activity of MTL neurons in neurosurgical patients while they learned new associations. Pairs of unrelated pictures, one of a person and another of a place, were used to construct a meaningful association modeling the episodic memory of meeting a person in a particular place. We found that a large proportion of responsive MTL neurons expanded their selectivity to encode these specific associations within a few trials: cells initially responsive to one picture started firing to the associated one but not to others. Our results provide a plausible neural substrate for the inception of associations, which are crucial for the formation of episodic memories.

The original publication can be found here.