Display the image caption in the Horizontal Gallery

Hello and thank´s for the new Horizontal Gallery – it´s much better than the old one!
But tell me: How can I display the image caption underneath each image (not in the lightbox – in the Horizontal Gallery)?

With the following function I can display the image title:

 function horizontal_gallery_subline(){
 ?>
 <script>
 (function($){
     $(window).load(function() {
         $('.av-horizontal-gallery-link').css('bottom', '30px');
         $('.av-horizontal-gallery-img').each(function(){
             var imgTitle = $(this).attr('title');
             $(this).after('<p class="text-under-image">' + imgTitle + '
');
             $(this).css({
                 'padding-bottom' : '20px',
                 'background-color' : 'transparent',
             });
             $('.text-under-image').css({
                 "text-align": "center",
                 "margin": "-20px 0",
                 "color": "#000",
             });
         });
     });
 })(jQuery);
 </script>
 <?php
 }
 add_action('wp_footer', 'horizontal_gallery_subline'); 

… how can I display the cation instead of the title?