Biology subjects

Bruera, A.

Publications and source records attributed to Bruera, A..

5 recordsLinked to original sources

bioRxiv2026

Linguistic information compensates for age-related decline in attentional filtering

As we age, understanding speech in social situations imposes an increasingly difficult challenge to the auditory system. However, the attentional mechanisms underlying age-related speech comprehension difficulties in multitalker situations remain unclear. We collected EEG signals while 63 normal hearing participants from 19 to 71 years performed a speech comprehension task involving a multitalker paradigm at individually adjusted target-to-distractor ratios. Combining trial-resolved multivariate temporal response function modeling with detailed behavioral comprehension responses, we provide a window into lower-level impairments and higher-level compensatory mechanisms across the adult life span. Neuro-behavioral correlations on a trial-by-trial level provide direct evidence for increased distractor representation underlying reduced behavioral performance in late adulthood. This points towards increased distractibility as a potential mechanism underlying age-related speech comprehension deficits. Additionally, at the behavioral and neural levels, we show that older adults relied more on higher-level linguistic information. Finally, we show that an increased reliance on word-level linguistic information may compensate for increased distractor tracking and adaptively support comprehension performance across the adult life span. Specifically, we directly show that increased reliance on higher-level processing can offset age-related impairments in attentional filtering.

neuroscience↗

bioRxiv2025

A novel approach to map the causal impact of brain stimulation on semantic processing with language models

Non-invasive brain stimulation (NIBS) studies on semantic cognition hold the promise of revealing the functional relevance of brain areas through causal intervention. A primary challenge, however, is that findings are often interpreted through binary distinctions between sets of stimuli (e.g. related/unrelated words, same/different semantic category). This approach ignores the analysis of individual words, which mirrors every-day language use and is crucial for understanding semantic cognition. In this work, we used semantic similarity, as measured by a language model, to investigate how Transcranial Magnetic Stimulation (TMS) effects on semantic cognition unfold at the level of individual words. We re-analyzed 5 publicly available TMS datasets, covering multiple stimulation sites and lexical semantics tasks. We propose a simple methodology that can straightforwardly be applied to any TMS experiment on semantic cognition, and showcase its potential to generate new insights. We modelled trial-level response times using the language model and computed the correlation between the two. We also repeated the analyses for two lower-level variables (word frequency and length). Importantly, for each dataset, we compared correlations for effective and control (sham or vertex) stimulation conditions. We found that, for the language model, correlation was almost always significantly different depending on the type of stimulation (effective or control). Our results provide evidence that the stimulation effect interacts with the meaning of individual words. However, a similar pattern emerged in some cases for word frequency and length, suggesting that the effects of TMS on cognition can be widespread, well beyond their intended functional target. Collectively, our results demonstrate that language models provide new insight into the impact of neurostimulation on semantic processing, complementing standard measures.

neuroscience↗

bioRxiv2025

Causal Contributions of Left Inferior and Medial Frontal Cortex to Semantic and Executive Control

Semantic control guides the targeted and context-based retrieval from semantic memory. The overlap with and dissociation from domain-general executive control in the frontal lobe remains contentious. Here, we used transcranial magnetic stimulation (TMS) to probe the functional relevance of the left inferior frontal gyrus (IFG) and pre-supplementary motor area (pre-SMA) for semantic and executive control. Across four sessions, 24 participants received 1 Hz repetitive TMS to each region individually, dual-site TMS targeting both regions sequentially (IFG followed by pre-SMA), and sham TMS. Participants then completed semantic fluency, figural fluency, and picture-naming tasks. Stimulation of either region broadly disrupted both semantic and figural fluency, suggesting shared functionality. However, electric field modeling of the induced stimulation strength revealed distinct specializations: The left IFG was primarily associated with semantic control, as evidenced by verbal fluency deficits, while the pre-SMA played a domain-general role in executive functions, affecting non-verbal fluency and cognitive flexibility (e.g., clustering and switching during semantic fluency). Notably, only dual-site TMS impaired accuracy in figural fluency, providing unique evidence for successful compensation of executive functions through either the left IFG or pre-SMA following single-site perturbation. These findings underscore the multidimensionality of cognitive control and suggest a flexible task-dependent contribution of the IFG to control processes, either as semantic-specific or general executive resource. Furthermore, they highlight the tightly interconnected network of executive control subserved by the left IFG and pre-SMA, advancing our understanding of the neural basis of semantic and executive functions.

neuroscience↗

bioRxiv2025

Attentional engagement with target and distractor streams predicts speech comprehension in multitalker environments

Understanding speech while ignoring competing speech streams in the surrounding environment is challenging. Previous studies have demonstrated that attention shapes the neural representation of speech features. Attended streams are typically represented more strongly than unattended ones, suggesting either enhancement of the attended or suppression of the unattended stream. However, it is unclear how these complementary processes support attentional filtering and speech comprehension on different hierarchical levels. In this study, we used multivariate temporal response functions to analyze the EEG signals of 43 young adults (24 women), examining the relationship between the neural tracking of acoustic and higher-level linguistic features and a fine-grained speech comprehension measure. We show that the neural tracking of word and phoneme onsets and word-level linguistic features in the attended stream predicted comprehension at the individual single-trial level. Moreover, acoustic tracking of the ignored speech stream was positively correlated with comprehension performance, whereas word level linguistic neural tracking of the ignored stream was negatively correlated with comprehension. Collectively, our results suggest that attentional filtering during speech comprehension requires target enhancement as well as distractor suppression at different hierarchical levels. Significance StatementIn social settings, speech comprehension is often challenged by the presence of multiple speakers talking simultaneously. The ability to focus on a relevant stream while ignoring irrelevant speech information in the background is crucial for successful and efficient interpersonal interactions. However, the precise neural mechanisms underlying this selective filtering process remain unclear. We establish the interplay of acoustic and higher-level information as objective markers of attentional selection and comprehension success.

neuroscience↗

bioRxiv2023

Family Lexicon: using language models to encode memories of personally familiar and famous people and places in the brain

Knowledge about personally familiar people and places is extremely rich and varied, involving pieces of semantic information connected in unpredictable ways through past autobiographical memories. In this work we investigate whether we can capture brain processing of personally familiar people and places using subject-specific memories, after transforming them into vectorial semantic representations using language models. First we asked participants to provide us with the names of the closest people and places in their lives. Then we collected open-ended answers to a questionnaire, aimed at capturing various facets of declarative knowledge. We collected EEG data from the same participants while they were reading the names and subsequently mentally visualizing their referents. As a control set of stimuli, we also recorded evoked responses to a matched set of famous people and places. We then created original semantic representations for the individual entities using language models. For personally familiar entities, we used the text of the answers to the questionnaire. For famous entities, we employed their Wikipedia page, which reflects shared declarative knowledge about them. Through whole-scalp time-resolved and searchlight encoding analyses we found that we could capture how the brain processes ones closest people and places using person-specific answers to questionnaires, as well as famous entities. Encoding performance was significant in a large time window (200-800ms). In terms of spatio-temporal clusters, two main axes where encoding scores are significant emerged, in bilateral temporo-parietal electrodes first (200-500ms) and frontal and posterior central electrodes later (500-700ms). We also found that XLM, a contextualized language model or large language model, provided superior encoding scores when compared with a simpler static language model as word2vec. Overall, these results indicate that language models can capture subject-specific semantic representations as they are processed in the human brain, by exploiting small-scale distributional lexical data. O_QDMy parents had five children. We now live in different cities, some of us in foreign countries, and we dont write to each other often. When we do meet up we can be indifferent or distracted. But for us it takes just one word. It takes one word, one sentence, one of the old ones from our childhood, heard and repeated countless times. All it takes is for one of us to say "We havent come to Bergamo on a military campaign," or "Sulfuric acid stinks of fart," and we immediately fall back into our old relationships, our childhood, our youth, all inextricably linked to those words and phrases. excerpt from Family Lexicon, by Natalia Ginzburg C_QD

neuroscience↗