Process range of columns not all matrix

I have a matrix data(91*921600) with 921600 samples.

I need to perform power spectral density using pwelch function only form column 1 until column 88 of the data matrix.

pwelch(data (1:88 , :))

But I need to include the remaining three columns 89, 90, and 91 in the same matrix without performing power spectral density on the values of columns 89, 90, and 91.

Hope you understand my question, I appreciate your kind assistance.