Table 1.

t test p values for anatomical grouping, mean OSI, and mean difference in preferred orientation (dPO) as a function of different numbers of core neurons required for inclusion of the cluster^a

No. of core neurons required for inclusion	Mean distance between core neurons; p value	Mean OSI of clusters; p value	Mean dPO of core neurons per cluster; p value	No. of recurring clusters
2 (original)	0.004**	0.309; ns	0.246; ns	71
3	0.019*	0.402; ns	0.852; ns	53
4	0.022*	0.418; ns	0.709; ns	36
5	0.050; ns	0.258; ns	0.428; ns	31
6	0.046*	0.123; ns	0.616; ns	23
7	0.028*	0.107; ns	0.433; ns	19
8	0.057; ns	0.352; ns	0.936; ns	16
9	0.183; ns	0.066; ns	0.756; ns	11
10	0.183; ns	0.066; ns	0.756; ns	11

^aOnly anatomical grouping was significant for a range of minimum core members; OSI and dPO were not.

**, p < 0.005;

*, p < 0.05.