Multisensory processes in old age

Paul J. Laurienti and Christina E. Hugenschmidt

Introduction

Typically when we think of development, we consider changes that begin at conception and culminate in adulthood. However, development is an ongoing process that proceeds until death and non-pathological changes occur in old age. Neuroscience dogma used to state that remodelling in the adult and aging brain was due solely to loss of neurons and connections. It is now well established that older brains do retain plastic capacity. This plasticity not only results in typical age-related variation, but allows for the use of interventions to direct neural changes.

Interactions between the senses are governed by the physical aspects of the stimuli such as temporal, spatial, and intensity properties. Higher-order cognitive processes also modulate the interactions between sensory modalities. Examples include the attentional state of the brain when the stimuli are presented, or the congruency of the stimuli. Sensory perception and higher-order processes are not static experiences in the brain; both evolve over the lifespan of the individual. It is known that even healthy aging people experience diminished sensory acuity in all five senses and have subtle alterations in cognitive processes like attention and memory. Given what we know about multisensory interactions, these common age-related changes have the potential to alter the probability and/or magnitude of integration in aging adults. This chapter will focus on the interplay between multisensory processing and the age-related cognitive and sensory changes that commonly occur in late development.