Young adults can be primed to re-use a syntactic structure across otherwise unrelated utterances but it is not known whether this phenomenon exists in older adults. In a dialogue task, young and older adults described transitive verb target pictures after hearing active or passive sentences. Both groups were more likely to produce a passive sentence following a passive prime than following an active prime (indicating syntactic priming), and this effect increased when the prime and target involved the same verb (indicating lexical boost). These effects were statistically equivalent in young and older adults, suggesting that the syntactic representations underlying sentence production are unaffected by normal aging.

Healthy aging does not affect all features of language processing equally. In this study, we investigated the effects of aging on different processes involved in fluent sentence production, a complex task that requires the successful execution and coordination of multiple processes. In Experiment 1, we investigated age-related effects on the speed of syntax selection using a syntactic priming paradigm. Both young and older adults produced target sentences quicker following syntactically related primes compared to unrelated primes, indicating that syntactic facilitation effects are preserved with age. In Experiment 2, we investigated age-related effects in syntactic planning and lexical retrieval using a planning scope paradigm: participants described moving picture displays designed to elicit sentences with either initial coordinate or simple noun phrases and, on half of the trials, the second picture was previewed. Without preview, both age groups were slower to initiate sentences with larger coordinate phrases, suggesting a similar phrasal planning scope. However, age-related differences did emerge relating to the preview manipulation: while young adults displayed speed benefits of preview in both phrase conditions, older adults only displayed speed preview benefits within the initial phrase (coordinate condition). Moreover, preview outside the initial phrase (simple condition) caused older adults to become significantly more error-prone. Thus, while syntactic planning scope appears unaffected by aging, older adults do appear to encounter problems with managing the activation and integration of lexical items into syntactic structures. Taken together, our findings indicate that healthy aging disrupts the lexical, but not the syntactic, processes involved in sentence production.

Structural priming refers to the tendency of speakers to repeat syntactic structures across sentences. We investigated the extent to which structural priming persists with age and whether the effect depends upon highly abstract syntactic representations that only encompass the global sentence structure or whether representations are specified for internal constituent phrasal properties. In Experiment 1, young and older adults described transitive verb targets that contained the plural morphology of the patient role ("The horse is chasing the frogs/ The frogs are being chased by the horse"). While maintaining the conceptual and global syntactic structure of the prime, we manipulated the internal phrasal structure of the patient role to either match (plural; "The king is punching the builders/ The builders are being punched by the king") or mismatch (coordinate noun phrase; "The king is punching the pirate and the builder/ The pirate and the builder are being punched by the king") the target. In both age groups, we observed limited priming of onset latencies, but robust effects of choice structural primingparticipants produced more passive targets following passive primeswhich critically did not vary dependent on whether the internal constituent structure matched or mismatched between the prime and target. Experiment 2 replicated these findings for the agent role: choice structural priming was unaffected by age or changes to the prime noun phrase type. This demonstrates that global, not internal, syntactic structure determines syntactic choices in young and older adults, as predicted by residual activation and implicit learning models of structural priming.

Sentence production requires rapid syntax generation and word retrieval. We investigated how healthy ageing affects these processes. In Experiment 1, syntactic priming significantly facilitated sentence production speed for both young and older adults. In Experiment 2, participants produced sentences with initial coordinate or simple phrases (e.g., the owl and the car move above the harp/the owl moves above the car and the harp); on half the trials, the second picture (car) was previewed. Without preview, both age groups were slower to initiate sentences with larger coordinate phrases, suggesting a similar planning scope. Young adults displayed speed benefits of preview both within and outside the initial phrase; however, older adults only displayed speed preview benefits within the initial phrase, and preview outside the initial phrase significantly increased error rates. Thus, syntactic planning scope appears unaffected by age, but there is age-related decline in the integration of lexical items into syntactic structures.

Successful sentence comprehension requires the binding, or composition, of multiple words into larger structures to establish meaning. Using magnetoencephalography, we investigated the neural mechanisms involved in binding at the syntax level, in a task where contributions from semantics were minimized. Participants were auditorily presented with minimal sentences that required binding (pronoun and pseudo-verb with the corresponding morphological inflection; “she grushes”) and pseudo-verb wordlists that did not require binding (“cugged grushes”). Relative to no binding, we found that syntactic binding was associated with a modulation in alpha band (8–12 Hz) activity in left-lateralized language regions. First, we observed a significantly smaller increase in alpha power around the presentation of the target word (“grushes”) that required binding (−0.05 to 0.1 s), which we suggest reflects an expectation of binding to occur. Second, during binding of the target word (0.15–0.25 s), we observed significantly decreased alpha phase-locking between the left inferior frontal gyrus and the left middle/inferior temporal cortex, which we suggest reflects alpha-driven cortical disinhibition serving to strengthen communication within the syntax composition neural network. Altogether, our findings highlight the critical role of rapid spatial–temporal alpha band activity in controlling the allocation, transfer, and coordination of the brain’s resources during syntax composition.

Structural priming refers to the tendency of speakers to repeat syntactic structures across sentences. We investigated the extent to which structural priming persists with age and whether the effect depends upon highly abstract syntactic representations that only encompass the global sentence structure or whether representations are specified for internal constituent phrasal properties. In Experiment 1, young and older adults described transitive verb targets that contained the plural morphology of the patient role (“The horse is chasing the frogs/ The frogs are being chased by the horse”). While maintaining the conceptual and global syntactic structure of the prime, we manipulated the internal phrasal structure of the patient role to either match (plural; “The king is punching the builders/ The builders are being punched by the king”) or mismatch (coordinate noun phrase; “The king is punching the pirate and the builder/ The pirate and the builder are being punched by the king”) the target. In both age groups, we observed limited priming of onset latencies, but robust effects of choice structural priming – participants produced more passive targets following passive primes – which critically did not vary dependent on whether the internal constituent structure matched or mismatched between the prime and target. Experiment 2 replicated these findings for the agent role: choice structural priming was unaffected by age or changes to the prime noun phrase type. This demonstrates that global, not internal, syntactic structure determines syntactic choices in young and older adults, as predicted by residual activation and implicit learning models of structural priming.

The authors argue that Ambridge’s radical exemplar account of language cannot clearly explain all syntactic priming evidence, such as inverse preference effects ( greater priming for less frequent structures), and the contrast between short-lived lexical boost and long-lived abstract priming. Moreover, without recourse to a level of abstract syntactic structure, Ambridge’s account cannot explain abstract priming in amnesia patients or cross-linguistic priming. Instead, the authors argue that abstract representations remain the more parsimonious account for the wide variety of syntactic priming phenomena.

Successful sentence comprehension requires the binding, or composition, of multiple words into larger structures to establish meaning. Using magnetoencephalography (MEG), we investigated the neural mechanisms involved in binding of language at the level of syntax, in a task in which contributions from semantics were minimized. Participants were auditorily presented with minimal sentences that required binding (pronoun and pseudo-verb with the corresponding morphological inflection; “she grushes”) and wordlists that did not require binding (two pseudo-verbs; “cugged grushes”). Relative to the no binding wordlist condition, we found that syntactic binding in a minimal sentence structure was associated with a modulation in alpha band (8-12 Hz) activity in left-lateralized brain regions. First, in the sentence condition, we observed a significantly smaller increase in alpha power around the presentation of the target word (“grushes”) that required binding (−0.05s to 0.1s), which we suggest reflects an expectation of binding to occur. Second, following the presentation of the target word (around 0.15s to 0.25s), during syntactic binding we observed significantly decreased alpha phase-locking between the left inferior frontal gyrus and the left middle/inferior temporal cortex. We suggest that this results from alpha-driven cortical disinhibition serving to increase information transfer between these two brain regions and strengthen the syntax composition neural network. Together, our findings highlight that successful syntax composition is underscored by the rapid spatial-temporal activation and coordination of language-relevant brain regions, and that alpha band oscillations are critically important in controlling the allocation and transfer of the brain’s resources during syntax composition.Significance statementEssential to the power of human language is our ability to comprehend and bind together multiple words into larger sentence structures to establish meaning. In this study, we investigated the electrophysiological mechanisms of binding language at the level of syntax (i.e., relating to the grammatical features). Our MEG results reveal that syntactic binding, relative to no binding, is associated with modulation in alpha band activity (8-12 Hz), including less power increases and inter-regional phase-locking, within and among language-relevant brain regions in the left hemisphere. We suggest that these alpha oscillations help control the allocation of the brain’s resources (in particular within the left inferior frontal gyrus and the left middle/inferior temporal cortex) to support syntactic binding in language comprehension.