Currently he is based at the 'Clinical Neuroanatomy Section, Department of Neurology, Center for Biomedical Research, University of Ulm, Germany.

[1] Braak's early research focused on the morphology of the central nervous system of chondrichthyan fishes.

In the holocephalan species Chimaera monstrosa (ratfish), he described, in the basal midline of the diencephalon, a previously unknown ependymall structure adjacent to the rostral part of the optic chiasma referred to as the ‘organon vasculare praeopticum’.

[4] Braak’s further research has focused on the morphology and pathoanatomy of the human central nervous system, in particular of the cerebral cortex (1980).

[7] in 2007, Braak and co-authors advanced a ‘dual-hit hypothesis’ about the pathogenesis of idiopathic Parkinson's disease, according to which an unknown pathogen akin to a slow-virus may enter the nervous system through both the nasal and intestinal mucosae, eventually resulting in a cascade of neurodegenerative events in the brain.