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Relating individual differences in cognitive abilities to neural substrates in older adults is of significant scientific and clinical interest, but remains a major challenge. Previous functional magnetic resonance imaging (fMRI) studies of cognitive aging have mainly focused on the amplitude of fMRI response, which does not measure neuronal selectivity and has led to some conflicting findings. Here, using local regional heterogeneity analysis, or Hcorr, a novel fMRI analysis technique developed to probe the sparseness of neuronal activations as an indirect measure of neuronal selectivity, we found that individual differences in two different cognitive functions, episodic memory and letter verbal fluency, are selectively related to Hcorr -estimated neuronal selectivity at their corresponding brain regions (hippocampus and visual-word form area, respectively). This suggests a direct relationship between cognitive function and neuronal selectivity at the corresponding brain regions in healthy older adults, which in turn suggests that age-related neural dedifferentiation might contribute to rather than compensate for cognitive decline in healthy older adults. Additionally, the capability to estimate neuronal selectivity across brain regions with a single data set and link them to cognitive performance suggests that, compared tofMRI-adaptation-the established fMRI technique to assess neuronal selectivity, Hcorr might be a better alternative in studying normal aging and neurodegenerative diseases, both of which are associated with widespread changes across the brain. [ABSTRACT FROM AUTHOR]

Objective: The primary objective was to determine whether age deficits in implicit sequence learning occur not only for second-order probabilistic regularities (event n - 2 predicts n), as reported earlier, but also for first-order regularities (event w - 1 predicts event n). A secondary goal was to determine whether age differences in learning vary with level of structure. Method: Younger and older adults completed a nonmotor sequence learning task containing either a first- or second-order structure. Learning scores were calculated for each subject and compared to address our research objectives. Results: Age deficits in implicit learning emerged not only for second-order probabilistic structure, but also for simple, first-order structure. In addition, age differences did not vary significantly with structure; both first and second order yielded similar age deficits. Discussion: These findings are consistent with the view that there is an associative binding deficit in aging and that this deficit occurs for implicit as well as explicit learning and across simple and more complex sequence structures. [ABSTRACT FROM AUTHOR]

This study investigated the effects of a simultaneous memory load on implicit associative sequence learning using the Triplets Learning Task (TLT). Participants in the Simultaneous condition held a secondary task memory load during the TLT, while those in the Sequential condition also performed both tasks, but successively, rather than simultaneously. Thus, the Simultaneous condition had a memory load during the TLT, while the Sequential condition did not. Probe blocks without the secondary task allowed separation of effects on learning from effects on its expression. Results revealed that the simultaneous memory load affected older, but not younger adults, by suppressing the expression of learning, not learning itself. Thus, older and younger adults can learn probabilistic associations while holding a simultaneous memory load, but the load can limit the extent to which older adults adapt their performance to environmental structure. Results are consistent with theories which propose that implicit associative learning does not call on limited capacity resources, and highlight the importance of distinguishing effects of dual tasks on the expression of learning from those on learning itself. [ABSTRACT FROM AUTHOR]

Few studies have investigated how aging influences the neural basis of implicit associative learning, and available evidence is inconclusive. One emerging behavioral pattern is that age differences increase with practice, perhaps reflecting the involvement of different brain regions with training. Many studies report hippocampal involvement early on with learning becoming increasingly dependent on the caudate with practice. We tested the hypothesis that the contribution of these regions to learning changes with age because of differential age-related declines in the striatum and hippocampi. We assessed age-related differences in brain activation during implicit associative learning using the Triplets Learning Task. Over three event-related fMRI runs, 11 younger and 12 healthy older adults responded to only the third (target) stimulus in sequences of three stimuli ("triplets") by corresponding key press. Unbeknown to participants, the first stimulus' location predicted one target location for 80% of trials and another target location for 20% of trials. Both age groups learned associative regularities but differences in favor of the younger adults emerged with practice. The neural basis of learning (response to predictability) was examined by identifying regions that showed a greater response to triplets that occurred more frequently. Both age groups recruited the hippocampus early, but with training, the younger adults recruited their caudate whereas the older adults continued to rely on their hippocampus. This pattern enables older adults to maintain near-young levels of performance early in training, but not later, and adds to evidence that implicit associative learning is supported by different brain networks in younger and older adults. [ABSTRACT FROM AUTHOR]

Few studies have investigated how aging influences the neural basis of implicit associative learning, and available evidence is inconclusive. One emerging behavioral pattern is that age differences increase with practice, perhaps reflecting the involvement of different brain regions with training. Many studies report hippocampal involvement early on with learning becoming increasingly dependent on the caudate with practice. We tested the hypothesis that the contribution of these regions to learning changes with age because of differential age-related declines in the striatum and hippocampi. We assessed age-related differences in brain activation during implicit associative learning using the Triplets Learning Task. Over three event-related fMRI runs, 11 younger and 12 healthy older adults responded to only the third (target) stimulus in sequences of three stimuli ("triplets") by corresponding key press. Unbeknown to participants, the first stimulus' location predicted one target location for 80% of trials and another target location for 20% of trials. Both age groups learned associative regularities but differences in favor of the younger adults emerged with practice. The neural basis of learning (response to predictability) was examined by identifying regions that showed a greater response to triplets that occurred more frequently. Both age groups recruited the hippocampus early, but with training, the younger adults recruited their caudate whereas the older adults continued to rely on their hippocampus. This pattern enables older adults to maintain near-young levels of performance early in training, but not later, and adds to evidence that implicit associative learning is supported by different brain networks in younger and older adults. [ABSTRACT FROM AUTHOR]

Background: During sentence processing we decode the sequential combination of words, phrases or sentences according to previously learned rules. The computational mechanisms and neural correlates of these rules are still much debated. Other key issue is whether sentence processing solely relies on language-specific mechanisms or is it also governed by domain-general principles. Methodology/Principal Findings: In the present study, we investigated the relationship between sentence processing and implicit sequence learning in a dual-task paradigm in which the primary task was a non-linguistic task (Alternating Serial Reaction Time Task for measuring probabilistic implicit sequence learning), while the secondary task were a sentence comprehension task relying on syntactic processing. We used two control conditions: a non-linguistic one (math condition) and a linguistic task (word processing task). Here we show that the sentence processing interfered with the probabilistic implicit sequence learning task, while the other two tasks did not produce a similar effect. Conclusions/Significance: Our findings suggest that operations during sentence processing utilize resources underlying non-domain-specific probabilistic procedural learning. Furthermore, it provides a bridge between two competitive frameworks of language processing. It appears that procedural and statistical models of language are not mutually exclusive, particularly for sentence processing. These results show that the implicit procedural system is engaged in sentence processing, but on a mechanism level, language might still be based on statistical computations. [ABSTRACT FROM AUTHOR]

The spatial contextual cuing task (SCCT) (Chun & Jiang, 1998) is an implicit learning task that appears to depend on the medial temporal lobes. This unusual combination has been of interest in functional imaging studies and research with clinical populations, where testing time is at a premium. However, the original version of the SCCT is time-consuming. In this study, 29 young adults (age range, 18-22 years) completed the SCCT, in which participants respond to the orientation of a target in arrays containing 11 distractors. Either 12 (original version) or 6 (abbreviated version) arrays repeated across the experiment, with the remaining novel arrays being generated randomly. Results revealed that the magnitude of learning (faster responses to repeated versus novel arrays) was larger when there were fewer repeated arrays, with no explicit awareness in most participants. Thus, the abbreviated version remained implicit, with the additional benefit of increasing the magnitude of learning. [ABSTRACT FROM AUTHOR]

Knowledge of sequential relationships enables future events to be anticipated and processed efficiently. Research with the serial reaction time task (SRTT) has shown that sequence learning often occurs implicitly without effort or awareness. Here, the authors report 4 experiments that use a triplet-learning task (TLT) to investigate sequence learning in young and older adults. In the TLT, people respond only to the last target event in a series of discrete, 3-event sequences or triplets. Target predictability is manipulated by varying the triplet frequency (joint probability) and/or the statistical relationships (conditional probabilities) among events within the triplets. Results reveal that both groups learned, though older adults showed less learning of both joint and conditional probabilities. Young people used the statistical information in both cues, but older adults relied primarily on information in the 2nd cue alone. The authors conclude that the TLT complements and extends the SRTT and other tasks by offering flexibility in the kinds of sequential statistical regularities that may be studied as well as by controlling event timing and eliminating motor response sequencing. [ABSTRACT FROM AUTHOR]

We investigated whether there is an age-related decline in implicit learning of an invariant association. Participants memorized letter strings in which a given letter always occurred in the second position (see Frick & Lee, 1995). Experiments 1 and 2 showed that young and older adults learned this regularity implicitly, with no significant age differences, even when a perceptual feature of the stimuli changed between encoding and test. Experiment 3 confirmed that learning had occurred during encoding, in that learning increased with the number of encoding presentations. We conclude that implicit learning of this invariant association is largely preserved in healthy aging, revealing another avenue by which older people continue to adapt efficiently to environmental regularities. [ABSTRACT FROM AUTHOR]

It has become widely accepted that sleep-dependent consolidation occurs for motor sequence learning based on studies using finger-tapping tasks. Studies using another motor sequence learning task [the serial response time task (SRTT)] have portrayed a more nuanced picture of off-line consolidation, involving both sleep-dependent and daytime consolidation, as well as modifying influences of explicit awareness. The present study used a variant of the SRTT featuring probabilistic sequences to investigate off-line consolidation. Probabilistic sequences confer two advantages: first, spontaneous explicit awareness does not occur, and second, sequence learning measures are continuous, making it easier to separate general skill from sequence-specific learning. We found that sleep did not enhance general skill or sequence-specific learning. In contrast, daytime enhancement occurred for general skill but not for sequence-specific learning. Overall, these results suggest that motor learning does not always undergo consolidation with sleep. [ABSTRACT FROM AUTHOR]

Recent studies have reported age deficits in learning sequences that contain subtle sequential regularities [e.g., Curran (1997) Psychological Research, 60(1-2), 24; D. V. Howard et al. (2004) Psychology and Aging, 19(1), 79; Howard, J. H. Jr, & Howard, D. V. (1997). Psychololgy and Aging, 12(4), 634]. This finding is of potential theoretical interest, but the contribution of sequence event timing to this deficit has not been investigated. This study used an alternating serial reaction time task to examine implicit sequence learning in young adults when event timing mimicked that experienced by older adults in previous research. We varied the response-to-stimulus interval directly in Experiment 1 and indirectly by degrading the stimuli to influence response time in Experiment 2. Results indicate that these "aged" young adults learned the higher-order sequence structure implicitly, but they learned less than young controls and more than old adults on some measures of implicit learning in both experiments. In addition, these two different experimental manipulations produced distinct patterns of deficits despite having nearly identical effects on event sequence timing. These findings suggest that event timing alone cannot explain the age deficits observed in high-order implicit sequence learning. [ABSTRACT FROM AUTHOR]

Age-related implicit learning deficits increase with sequence complexity, suggesting there might be limits to the level of structure that older adults can learn implicitly. To test for such limits, we had 12 younger and 12 older adults complete an alternating serial reaction time task containing subtle structure in which every third trial follows a repeating sequence and intervening trials are determined randomly. Results revealed significant age deficits in learning. However, both groups did learn the subtle regularity without explicit awareness, indicating that older adults remain sensitive to highly complex sequential regularities in their environment, albeit to a lesser degree than younger adults. [ABSTRACT FROM AUTHOR]

The influence of structure and age on sequence learning was investigated by testing 24 young and 24 older participants for 10 sessions in an alternating serial response time task in which pattern trials alternated with random trials. Individuals encountered lag-2 or lag-3 structure, and learning was measured by the difference (in response time and accuracy) between pattern and random trials. Both ages learned lag-2 structure, but the young learned more than the older participants. Only the young people learned lag-3 structure, and they did so more slowly and to a lesser degree than they learned lag-2 structure. These age deficits in higher order sequence learning after extended practice are consistent with simultaneity theory and with theories positing that age-related deficits in neuromodulation lead to less distinctive representations. [ABSTRACT FROM AUTHOR]

Investigates whether there are age differences in implicit learning of non-spatially sequential patterns. Performance of alternating serial reaction time task; Alternation of predictable pattern events with random unpredictable ones; Pattern sensitivity of young people in comparison to the aged.

Previous studies using simple, repeating patterns have suggested that the knowledge gained in early sequence learning is not effector-specific in that it transfers to muscle groups other than those used during training. The current experiments extended these findings to transfer after extensive practice with probabilistic sequences using a task on which people fail to gain declarative knowledge of the regularity. Specifically, an alternating serial reaction time (ASRT) task was used in which predictable and unpredictable trials alternated. Participants responded for the first five sessions using their right hand, then switched to the left hand for the sixth session. Stimuli were spatial in the first experiment and nonspatial in the second. Significant near-perfect transfer of pattern knowledge was seen in both experiments, suggesting that muscle-specific information for either the fingers or the eyes cannot explain the observed learning. [ABSTRACT FROM AUTHOR]

Presents a study that examined whether age-related deficits in implicit learning begin in middle age. Pattern sensitivity by age and processing speed; Information on the use of serial reaction time; Determination of median reaction time.

Investigates how individuals learn to classify sequentially structured patterns of complex environmental sounds. Administration of three experiments; Effectiveness of observation trials for target acquisition; Implications of the findings for pattern classification theory.

3 experiments examined serial pattern learning in younger and older adults. Unlike the usual repeating pattern, the sequences alternated between events from a repeating pattern and those determined randomly. The results indicated that no one was able to describe the regularity, but with practice every individual in all 3 age groups (including old old) became faster, more accurate, or both, on pattern trials than on random trials. Although this indicates that adults of all ages are able to learn second-order statistical dependencies in a sequence, age-related deficits were obtained in the magnitude of pattern learning. There were also age differences in what was learned, with only younger people revealing sensitivity to higher order statistical dependencies in the sequence. In addition, whereas younger people revealed evidence of their pattern learning in a subsequent conceptually driven production test, young-old and old-old people did not. [ABSTRACT FROM AUTHOR]

Language learners must place unfamiliar words into categories, often with few explicit indicators about when and how that word can be used grammatically. Reeder, Newport, and Aslin (2013) showed that college students can learn grammatical form classes from an artificial language by relying solely on distributional information (i.e., contextual cues in the input). Here, 2 experiments revealed that healthy older adults also show such statistical learning, though they are poorer than young at distinguishing grammatical from ungrammatical strings. This finding expands knowledge of which aspects of learning vary with aging, with potential implications for second language learning in late adulthood. (PsycINFO Database Record [ABSTRACT FROM AUTHOR]