[Neurobiological relations and aging].

Of the different aspects of a series of neurobiological changes that take place throughout the life cycle of an individual, in this paper we examine those involved in the aging process. These changes have been associated on different scales, including on a macroscopic level, that take into account variations in the shape, weight and volume of the brain and other encephalic structures. A part of the information about the weight seems to be incompatible and hence its incompatibility has been questioned and argued from a quantitative perspective. The functional option has been proposed as an alternative in the maintenance of normal brain functioning, as have changes on the microscopic scale in neuronal processes, the reduction in number of neurons in certain parts of the brain, which has also been questioned for the case of olfactory nerve fibres, and finally changes that take place on the molecular scale in the alteration of some neurotransmitters in certain parts, modifications suffered by mitochondrial enzymes and others that depend on the genome. These aspects have all been taken into consideration along with a resulting physiological relation in an attempt to gain a slightly more holistic, although still fragmented, view of the process, and to consider neoteny as an evolutionary strategy in the human species that serves to maintain brain functioning.