Implicit Learning in Aging: Extant Patterns and New Directions

Abstract

Research suggests that the striatum plays an important role in implicit learning (IL). The striatum exhibits marked age-related morphological and neurochemical losses. Yet, behavioral studies suggest that IL is generally well preserved in old age, and that age-related differences emerge only when highly complex IL tasks are used. In this review, we integrate behavioral and neuroimaging evidence on IL in aging. We suggest that relative stability of IL in old age may reflect neural reorganization that compensates for age-related losses in striatal functions. Specifically, there may be an age-related increase in reliance on extrastriatal regions (e.g., medial-temporal, frontal) during IL. This reorganization of function may be beneficial under less taxing performance conditions, but not when task demands become more challenging.

Predicting the future: From implicit learning to consolidation

“…As implicit sequence learning is highly dependent on the integrity of the striatal network, and age-related structural and biochemical losses are pronounced in the striatal complex and connected prefrontal areas (Dennis and Cabeza, 2011;Raz et al, 2005;Rieckmann and Bäckman, 2009), how online and offline sequence learning is affected by aging is an important question.…”

“…In experimental settings, implicit learning is defined as the acquisition of co-occurrence/dependencies between stimuli or trials, and is expressed only through performance (Frensch, 1998;Howard et al, 2004;Rieckmann and Bäckman, 2009). In the past decades, several tasks have been developed to tap into implicit learning.…”

“…In these tasks, the covariation of certain stimuli (e.g., in a letter string/a set of cards) has predictive information, in contrast to sequence learning tasks, where participants have to predict the onset of a stimulus based on the preceding stimuli (Rieckmann and Bäckman, 2009). Evidence suggests that the latter type of task has partly different underlying mechanisms and activates partly different brain structures (Greene et al, 2007;Jimenez and Vázquez, 2011;Poldrack et al, 2005); therefore, it is important to differentiate between these two types of tasks.…”

A Review of Models in Experimental Studies of Implicit Language Learning

“…Fu et al (2008Fu et al ( , 2010 adopted two second-order conditional sequences of numbers in a target-location task, in which the location of each number was determined by the locations of the previous two numbers. Implicit sequence learning was also studied frequently in psychological studies of aging and other issues as a window through which to look inside human brain function (Rieckmann & Bäckman, 2009).…”

“…Most sequence learning studies belong to the first type (Clegg et al, 1998;Cleeremans & McClelland, 1991;Nissen & Bullemer, 1987;Rieckmann & Bäckman, 2009): subjects are not told anything about the existence of rules, but only asked to react to questions as by pressing a fixed key when seeing an element or to memorize sequences in order. These kinds of inductive activities, however, are very likely to lead attention to orders and bring about the construction of hypotheses about sequence.…”