Recently, there has been quite the upheaval in thought surrounding the functionality of small brains. Quite a number of studies have shown that the size of an organisms brain does not reflect its inherent intelligence, as was thought for the longest time.
What is being found now is larger brains are more frequently found in larger organisms not because they are more intelligent, but because they have more body mass to regulate. Having a larger body requires more computing power to operate all the necessary functions. This is why Cetaceans have some 200 billion neurons yet are less intelligent then humans with our measly 85 billion neurons. A whale has much more bio-mass, larger muscles to regulate, and more massive systems or operate. As such, they need more neurons to simply perform daily life functions.
As well as needing more neurons for regulating larger amounts of tissue, larger brains are also known to have a great deal of redundancy. Entire pathways are written and re-written again. While this does help in the case of injury or for increased parallel processing, the extraneous neural routes also consume a great deal more energy, making the over all system less efficient. This redundancy is seen consistently throughout the animal kingdom as brains increase in size. The reason for this is the genetic code. Our genes do not list every neuron nor does it list every connection. If it were to attempt this, it would be hundreds if not thousands of times larger then it currently is. The reason for this is that our genes encode our neurons as a repeating pattern. So when the genes are read to begin forming the organism after conception, a base template is created and replicated through multiple iterations until the requisite amount of neural tissue is formed.
This trend can be seen in the other direction as well, as we are now learning. An insect does not have that much tissue to constantly regulate, so its required amount of neurons for basic life functions is relatively few. This allows for the remainder to be used for other processes. In fact only a few hundred are required for tasks such as counting and a mere few thousand neurons are needed to produce a very basic consciousness.
With this new information, we are realizing that insects are much more then simple reactionary beings, as we have assumed for so long. They are able to recognize objects and individuals, categorize objects, count how many of something there is and quite possibly much more. This, quite obviously, makes insects far more interesting. There is even a chance that when you watch a praying mantis and she appears to be looking back at you, she might just be pondering you just as you are contemplating her.
What really counts is the number of synapses, not the overall number of neurons. More synapses means more links, more connections. The more connections you have, the better parallel processing speed you have. More links also grant greater storage by being able to connect disparate concepts together in the mind.
This discovery is also quite important to computer scientists. With the knowledge that synapses, not neuron count, is what really matters, scientists and engineers can now start creating smaller systems of emulated neurons that will have greater functionality then we previously have had. Instead of relying on redundancy as higher organisms do, we could emulate neurons with an increased inter connectivity. This would grant a more complex system, but being built from a much simpler construct. Such knowledge may allow such neural emulations to bound forward faster then we had previously predicted.