Justo Gonzalo (1910-1986): a pioneer of brain dynamics

The present work offers an overview of the pioneering contributions of the neuroscientist Justo Gonzalo to the study of the human cerebral cortex, within the historical context of his time and in relation to current research. Gonzalo initially trained under Gonzalo Rodríguez Lafora (a disciple of Santiago Ramón y Cajal) and always maintained a close relationship with him and his circle, connecting him to the Spanish Neurological School (Cajal's school). He also trained in neurology in Austria and Germany (1933-1935). The research he called brain dynamics began during the Spanish Civil War (1936-1939) in a military hospital in Valencia, based on the study of patients with war-related brain injuries. Based on physiological criteria, Gonzalo described what he termed central syndrome of the cortex: a multisensory and bilaterally symmetrical disorder caused by a unilateral parieto-occipital cortical lesion in an associative area. He brought to light singular perceptual phenomena, and was the first to study inverted or tilted perception (visual, tactile, and auditory), the improvement of perception through increased stimulus intensity or the presence of additional stimuli, as well as other phenomena that remain little known today. These findings and the study of different cortical syndromes led Gonzalo to propose that the specificity of brain functions is gradually distributed throughout the cerebral cortex, giving rise to cortical gradients, whose overlap would result in fairly nonspecific or multisensory adaptive regions. This unitary approach went beyond the rigid cortical parcellation for the anatomical localization of brain functions, and is closely aligned with current studies. The interpretation of the central syndrome as analogous to the normal case, but with reduced excitability, led Gonzalo to apply scaling concepts that enabled him to develop formalizations and generalizations. He conducted this research in Spain, under very difficult conditions, with the support of the Cajal Institute. Despite the excellent international reception of his works in Spanish during the 1940s and 1950s, his contributions are scarcely known today due to the lack of timely publications in other languages. The publication of his works in English in 2023 has partially filled this gap.