memory error

Having issue reading in the HCP groupPCA data; get a memory error

```
f = 'HCP_S900_820_rfMRI_MSMAll_groupPCA_d4500ROW_zcorr.dconn.nii'    
dcon = np.tanh(nib.load(f).get_data()[:])
```

Do you have any suggestions on this? 

(Looks like maybe this is what the hcp_corr repo is for; but can't quite tell if that gives same output as the above line)


Thx.

