changing the values around an indexed number

Is there a way that i could write a loop that would change the values around an indexed value. So, say that there is a matrix=[1 2 3 4; 5 6 7 8] and i want to index the value of 2. Could i then change the value around the indexed number. Could i change the values of 1,3,and 4 based on the stored index value for 2??

[Stephen23]

What kind of index: a logical index, a linear index or a subscript index? Do you already have the index, or just the value/s of the number that you want to change?

[Sanwal Yousaf]

I have the indexing, i want to change the values surrounding that number using the index that i have. I hope that this clarifies my predicament