Incremental training increases the plasticity of the auditory space map in adult barn owls

Abstract

The plasticity in the central nervous system that underlies learning is generally more restricted in adults than in young animals. In one well-studied example, the auditory localization pathway has been shown to be far more limited in its capacity to adjust to abnormal experience in adult than in juvenile barn owls. Plasticity in this pathway has been induced by exposing owls to prismatic spectacles that cause a large, horizontal shift of the visual field. With prisms, juveniles learn new associations between auditory cues, such as interaural time difference (ITD), and locations in visual space, and acquire new neurophysiological maps of ITD in the optic tectum, whereas adults do neither. Here we show that when the prismatic shift is experienced in small increments, maps of ITD in adults do change adaptively. Once established through incremental training, new ITD maps can be reacquired with a single large prismatic shift. Our results show that there is a substantially greater capacity for plasticity in adults than was previously recognized and highlight a principled strategy for tapping this capacity that could be applied in other areas of the adult central nervous system.

Learning problems, delayed development, and puberty

“…Intrinsic to the latter explanation is the possibility that puberty may actually enable further improvement on slowly acquired skills in normal development. Thus, the present data provide indirect evidence that puberty affects brain development in humans on skills other than language acquisition (39), as is expected from animal studies (39,40), and indicate that investigations of individuals with perceptual delays but otherwise intact intellectual skills might help determine the role of puberty in human brain development.…”

“…Two pieces of circumstantial evidence support this idea: Human puberty begins at approximately the same time as the developmental arrest (38), and puberty in humans and other animals is associated with neurological changes that are thought to reduce brain plasticity (39,40). To account for the current results, we assume that listeners with LPs and controls both reach the stage of puberty that affects perceptual development at Ϸ10 years of age.…”

Cochlear implants: A remarkable past and a brilliant future

“…The ideal training procedure for an infant or young child may be quite different from the ideal procedure for older children or adults due to differences in brain plasticity. For example, the "step size" for increments in the difficulty of a training task may need to be much smaller for adults than for infants and young children (Linkenhoker and Knudsen, 2002). However, all patients may benefit from appropriately designed procedures, that respect the differences in brain plasticity according to age.…”

Synaptogenèses et épigenèses cérébrales

“…La restauration de la plasticité synaptique dans une modalité sensorielle donnée, par exemple dans le cortex visuel, peut également être stimulée par l'activation d'autres modalités sensorielles, motrices, et cognitives, dans un environnement enrichi [25,26]. La restauration peut s'effectuer en privilégiant le paramètre temps : des réapprentissages par incréments [27], sur une longue durée, peuvent réorganiser les circuits neurono-synaptiques. Les thérapies comportementales cognitives peuvent aussi réorganiser, au moins fonctionnellement, des circuits corticaux [28].…”