Differentiating Beyond Name Agreement for Picture Naming: Insight From Age-Related Selection Deficits.

Purpose Pictures consistently referred to by the same name (high agreement) are named faster than pictures that elicit inconsistent responses across individuals (low agreement). Although this effect is more pronounced in older adults apparently due to slower lexical selection, it is unclear whether this is consistent for different types of low agreement pictures. We investigated whether pictures with different sources of disagreement have differing selection requirements, as indexed by naming latencies. Method Picture naming latencies were compared for 20 young (ages 18-35 years) and 20 older adults (ages 60-80 years) across 3 object naming conditions: high name agreement, low name agreement due to multiple correct names, and low agreement due to abbreviations and elaborations. Results Compared to high agreement items, responses were slower specifically for low agreement items with multiple names, and to a lesser extent, items with abbreviations and elaborations ( p < .001). Older adults were slower than younger adults, especially for low agreement items with abbreviations and elaborations ( p = .031). Conclusions Our findings indicate differential lexical selection requirements for low agreement pictures, depending on the reason for agreement being low. This demonstrates the importance of differentiating the source of disagreement in any experimental or clinical assessment of picture naming.

Improved language production with transcranial direct current stimulation in progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is an atypical parkinsonian disorder that can present with language production deficits in addition to the characteristic progressive parkinsonian motor symptoms. Although typical parkinsonism treatments such as pharmacotherapy are not effective in PSP, non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) have shown promise for treating cognitive deficits relating to this disorder. We report the case of KN, who presented with reduced verbal fluency and connected speech production in the context of PSP. KN completed a set of language tasks, followed by an alternate version of the tasks in conjunction with either sham or active tDCS over the left dorsolateral prefrontal cortex (DLPFC) across four sessions. Results showed improved performance with active stimulation compared to sham stimulation for phonemic fluency and action naming, as well as mixed results suggesting possible benefits for connected speech production. There were no benefits of active stimulation for control tasks, indicating that tDCS can produce specific benefits for phonemic fluency, action naming, and connected speech production in PSP. These promising, preliminary findings warrant further investigation into whether these benefits of tDCS can be a useful therapeutic tool for PSP patients to maintain language.

Age-related differences in idea generation and selection for propositional language.

Conceptual preparation mechanisms such as novel idea generation and selection from amongst competing alternatives are critical for language production and may contribute to age-related language deficits. This study investigated whether older adults show diminished idea generation and selection abilities, compared to younger adults. Twenty younger (18-35 years) and 20 older (60-80 years) adults completed two novel experimental tasks, an idea generation task and a selection task. Older participants were slower than younger participants overall on both tasks. Importantly, this difference was more pronounced for task conditions with greater demands on generation and selection. Older adults were also significantly reduced on a semantic, but not phonemic, word fluency task. Overall, the older group showed evidence of age-related decline specific to idea generation and selection ability. This has implications for the message formulation stage of propositional language decline in normal aging.

Improved conceptual generation and selection with transcranial direct current stimulation in older adults.

INTRODUCTION: Normal aging is associated with deficits in various aspects of spoken language production, including idea generation and selection, and involves activity in frontal brain areas including left inferior frontal cortex (LIFG). These conceptual preparation processes, largely involving executive control, precede formulation and articulation stages and are critical for language production. Noninvasive brain stimulation (e.g., transcranial direct current stimulation, tDCS) has proven beneficial for age-related fluency and naming deficits, but this has not been extended to conceptual preparation mechanisms. METHOD: We investigated whether tDCS could facilitate idea generation and selection in 24 older adults aged 60-80 years. In the first phase, participants completed an idea generation test and a selection test with no stimulation. In the second phase they completed an alternate version of the tests in conjunction with either active or sham stimulation. Active stimulation applied 1-mA anodal tDCS over LIFG for the test duration (10 min). RESULTS: Responses were faster following active stimulation than following sham. Furthermore, improvements were specific to test conditions involving novel generation (p = .030) and selection (p = .001) and were not observed in control conditions for which these mechanisms were minimally involved. CONCLUSIONS: We concluded that tDCS benefits conceptual preparation mechanisms. This preliminary evidence is an important step for addressing age-related decline in propositional language generation, which is integral to conversational speech. This approach could also be extended toward rehabilitation in neurological patients with deficits in these processes.