If you can provide a MAT file with the data, it would be helpful in answering the question more concretely.
You should be able to do this with islocalmax. Once you've used whatever options you've used to identify your maximum point ('MinProminence', etc.), you can call islocalmax without any filtering options to get all the local maxima. This will be the set of all points that are strictly larger than their neighbors. The detected maxima immediately prior to your target maxima should be what you're looking for.
