No two neurons are the same. Even neurons of the same type (i.e. purkinje cells) behave differently. This fact is often overlooked as an important functional feature of the brain, and instead chalked up to biological impreciseness. In their recent Nature article, Krishnan Padmanabhan and Nathaniel Urban think there’s an important reason behind all the diversity. They studied the “intrinsic differences” in the molecular signatures and firing behaviors of mitral cells in the mouse olfactory bulb, and by differentially stimulating different cells concluded that:
Although a number of mechanisms have been proposed to account for the origin and extent of these intrinsic differences, we found that differences in intrinsic biophysical heterogeneity can be important [for] neural coding.
In other words, the intrinsic differences between neurons are not biological mistakes – they are adaptive functions for the complex neural coding of stimulus information.
100 billion neurons, and each one is functionally different? I’m having trouble coding that one…