3D matrix dimension change

dear sir/ma'am

I have a 3D matrix a(n:n:4) which is written as

a1=a(:,:,1);
a2=a(:,:,2);
a3=a(:,:,3);
a4=a:,:,4);
for t=1:n
    a_matrix=[a1(t,t) a2(t,t);a3(t,t)a4(t,t)]; 
end

This code gives the result 2*2 matrix value from 3D matrix which is as expected. But when I am writting this code like:

a_matrix=a(t,t); ---> it gives only 1*1 matrix value and

a_matrix=a(n:n:4) (t,t);----.> it gives syntex error

How I will get expected value of 2*2 matrix using this general code not using by 1st code?

Thank you.

[Walter Roberson]

%for any given t value
a_matrix = reshape(a(t,t,:),2,2).';

[anindita Roy]

Yes.It is working. Thank you.