def voxel_dict_summary(voxel_dict, cortical_area=[], verbose=False):
    """
    Returns a summary report of voxel_dict contents

    {
    cortical_area_1: ((block_ref_1, neuron_count), (block_ref_2, neuron_count), (block_ref_3, neuron_count),...),
    cortical_area_2: ((block_ref_1, neuron_count), (block_ref_2, neuron_count), (block_ref_3, neuron_count),...),
    ...
    }
    """

    stats = dict()

    for area in voxel_dict:
        if area in cortical_area or not cortical_area:
            stats[area] = set()
            for block in voxel_dict[area]:
                stats[area].add((block, len(block)))

    if verbose:
        for area in stats:
            print(area)
            for block in stats[area]:
                print("----", block[0], block[1])

    return stats