Estimating the energy requirements for long term memory formation

TL;DR

This paper estimates the energy cost of long-term memory formation in biological systems, finding it to be around 10mJ per bit, and compares it with biophysical and computer hardware estimates to understand its expense.

Contribution

It provides a quantitative estimate of the energy required for memory formation and compares it with other systems to explore why biological memory storage is costly.

Findings

Memory formation costs about 10mJ per bit.

Biological memory storage is energetically expensive.

Comparison with hardware estimates highlights the high energy demand.

Abstract

Brains consume metabolic energy to process information, but also to store memories. The energy required for memory formation can be substantial, for instance in fruit flies memory formation leads to a shorter lifespan upon subsequent starvation (Mery and Kawecki, 2005). Here we estimate that the energy required corresponds to about 10mJ/bit and compare this to biophysical estimates as well as energy requirements in computer hardware. We conclude that biological memory storage is expensive, but the reason behind it is not known.