Liens entre le déclin sensoriel et cognitif dans le vieillissement normal : revue critique de la littérature et apports de l’approche incarnée et située de la cognition

Biological aging impacts many organs including sensory's ones and the brain, and thus, cognition. Research has shown that the sensory and cognitive decline are positively correlated. The main data from this literature are firstly reviewed in the present article. Then, the four main hypotheses that are generally proposed to explain these associations are presented. According to them, sensory decline is supposed to cause cognitive decline, or vice-versa, or these concomitant changes result from the general alteration of the nervous system. However, none of them seems able to account for all of the existing data. Moreover, the precise mechanisms that may drive these associations remain to be clarified. The rest of the article is then dedicated to the embodied and situated cognition approach as it provides a particularly interesting and adequate framework to account for these links. Indeed, according to this approach, cognitive representations are grounded in their sensorimotor properties. In other words, cognitive functioning is not conceived as detached from sensory functioning, but instead directly dependent of it. Representations are thus thought to emerge from the sensorimotor simulation of the properties involved in these representations. Therefore, sensory decline should directly impact cognitive performance. It is then hypothesized that older adults have low-resolution representations decreasing the signal on noise ratio of traces, increasing sensorimotor interferences and thus decreasing cognitive performance. This approach leads to consider low and high levels of sensory and perceptual functioning, which are both impaired in aging. Therefore, the repercussion of the sensory-perceptual decline is not only valid for present processing, but also extend to all past knowledge. Several predictions are then proposed on (1) the link between high-level perceptual functioning and cognitive functioning in older adults; (2) the possible interaction in young adults between sensory and high-level perceptual functioning as a function of the level of interference of the material involved; (3) the possible link between the motor and cognitive functioning in older adults. The clinical consequences in terms of cognitive stimulation of such a perspective will close the article. It is proposed to develop a stimulation program based on pattern separation mechanism to better process sensory interference in order to train older adults to improve cognitive precision and thus performance.