1. Grupo de Investigacion en Envejecimiento. Division Ciencias de la Salud, Universidad Anahuac Mayab. Merida, Yucatan, Mexico
2. Laboratorio de Neurobiologia del Sueno. Depto. de Fisiologia, Facultad de Medicina, Universidad de la Republica, Montevideo, Uruguay
3. Institute of Psychiatry. Federal University of Rio de Janeiro. Rio de Janeiro, Brazil
4. Health School Sciences, Polytechnic Institute of Porto, Porto, Portugal
5. Laboratory of Panic and Respiration, Institute of Psychiatry of Federal University of Rio de Janeiro, Rio de Janeiro, Brazil