A model that attempts to explain why numerical cognition lies in the parietal lobes and explains how numbers are related to other kinds of quantities
Bueti, D. & Walsh, V. (2009). The parietal cortex and the representation of time, space, number and other magnitudes. Philosophical Transactions of the Royal Society B-Biological Sciences, 364(1525), 1831–1840.
One experiment, out of many done by this lab, showing that neurons in the monkey cortex are tuned to particular numbers. This study shows an equivalence between visual and auditory numbers
Nieder, A. (2012). Supramodal numerosity selectivity of neurons in primate prefrontal and posterior parietal cortices. Proceedings of the National Academy of Sciences of the United States of America, 109(29), 11860–11865.
If your language only contains unique number words up to 4 then can you do arithmetic with larger numbers? This study suggests the answer is “yes” provided the arithmetic is approximate
Pica, P., Lemer, C., Izard, V., & Dehaene, S. (2004). Exact and approximate arithmetic in an Amazonion indigene group with a reduced number lexicon. Science, 306, 499–503.
This study shows a relationship with quantity estimation (of collections of dots) and scores on school based math
Halberda, J., Mazzocco, M. M. M., & Feigenson, L. (2008). Individual differences in non-verbal number acuity correlate with maths achievement. Nature, 455(7213), 665–U662.