Brains are expensive, but cognition is often cheap

Area of Science:

• Neuroscience
• Metabolic research
• Cognitive science

Background:

• The prevailing view posits that cognitive activity is metabolically expensive.
• This belief stems from the assumption that increased neural computation necessitates higher energy demands.

Purpose of the Study:

• To challenge the assumption that cognitive tasks are always metabolically costly.
• To explore the metabolic costs associated with maintaining resting brain states versus engaging in cognitive tasks.
• To investigate the implications for understanding brain function, behavior, and evolution.

Main Methods:

• Review of experimental evidence from brain imaging and whole-body measurements in mammals.
• Analysis of metabolic costs during cognitive tasks and resting states.

Main Results:

• Cognitive tasks typically show minimal or no increase in overall energy expenditure.
• Maintaining a resting brain state can be metabolically comparable to engaging in explicit cognitive tasks.
• Inactivity may not be an effective energy-saving strategy.

Conclusions:

• The metabolic cost of cognitive activity is often overestimated.
• Understanding homeostatic mechanisms that stabilize brain energy expenditure is crucial for neural computation.
• The evolutionary persistence of non-instrumental activities can be explained by the lack of significant metabolic savings from reduced exploration.