Animals near the [ectotherm](https://en.wikipedia.org/wiki/Ectotherm) side of the endotherm-ectotherm spectrum rely on external heat sources to regulate their body temperature. When they are cold, overal enzyme activity and metabolic rate is lower.

My question is if these animal tend to 'think' slower when cold?

To be honest, my knowledge of brain physiology is very sketchy, I'm not sure biochemical activity plays a large role vs. electrical and diffusion processes and the latter would be less temperature dependant. So I'm not sure we would expect ectotherms to 'think' slower.

OTOH, [wikipedia on endotherms](https://en.wikipedia.org/wiki/Endotherm#Regional_endothermy) states ...

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> Some ectotherms, including several species of fish and reptiles, have been shown to make use of regional endothermy, where muscle activity causes certain parts of the body to remain at higher temperatures than the rest of the body. This allows for better locomotion and *use of the senses in cold environments*.
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The source for this claim is [on google books](https://books.google.de/books/about/Environmental_Physiology_of_Animals.html?id=r9gvbjRFyRgC&redir_esc=y), just not the relevant pages (Willmer, Pat; Stone, Graham; Johnston, Ian (2009). *Environmental Physiology of Animals*) 

I'm also not sure how to define 'thinking' within this wide range of animals, I'll take any metric for speed at cognitive tasks or reacting to external stimuli.