This works just like usual AIC, but instead calculates the small sample (or high dimensional) corrected version from Hurvich and Tsai
$$AICc = -2\log LHD + k*df*\frac{n}{n-df-1}.$$
References
Hurvich, C. M. and C-L Tsai, 1989. "Regression and Time Series Model Selection in Small Samples", Biometrika 76.