Numeracy, the ability to understand and use numbers and basic numerical concepts, has significant implications throughout a person's life. Like other cognitive abilities, numeracy tends to decline with age (1), and this decline can be a vulnerability factor for the elderly when it comes to solving everyday tasks (2). The reasons behind this decline with age are still not fully understood. However, gaining insight into this phenomenon could have important implications for distinguishing between normal and pathological aging, as well as for designing environments effective for elderly. Studies have shown that numerical cognition involves a highly-integrated brain network comprising frontal and parietal cortices, with particular importance placed on the intraparietal sulcus and the fusiform gyrus (3). It is possible to hypothesize that a functional impairment of these areas due to aging leads to the presence of dyscalculia. In this study, we employed a parity judgment task to investigate variations in number cognition between older and younger subjects. Since numeracy is associated with both symbolic and non-symbolic number representation, the task involved three different numerical formats: Arabic digits, finger representations, and dots. Twenty-eight healthy subjects participated in the study: 14 young participants (64.28% female, mean age: 24.64±3.67) and 14 older participants (42.8% female, mean age: 70.57±4.34). EEG data were recorded using an actiCHamp Plus amplifier (Brain Products, GmbH) with a 64-electrode setup based on the actiCap 10–20 system (Brain Products, GmbH). Stimuli were presented using E-Prime 3.0 (PST, USA), and responses were recorded using a Chronos device (PST, USA). The EEG data were analyzed in Matlab (MathWorks, USA) for time/frequency analysis and source identification. To account for the absence of individual MRI scans, pseudo-individual anatomies were created by adapting a template MRI (ICBM152) using digitized head points obtained with a Polhemus Fastrak (Polhemus, USA). Our findings reveal a discrepancy in the activation levels of all the primary cortical areas involved in numerical cognition between the young and old groups, with a general reduction in activation and increased latency observed in the latter group. In the same group, numerical stimuli also induce a wider cortical response. Interestingly, among non-symbolic number representations, dots induce the lowest activation of the parietal cortex in the elderly. We conclude that the reduced activity of the main cortical areas may contribute to the physiological decay in numeracy skills in the elderly and that the recruitment of other cortical areas may serve as a compensatory mechanism.

Symbolic and non-symbolic numerical representations. Cortical dynamics in old and young subjects, an EEG study.

Carla Meloni
Membro del Collaboration Group
;
Rachele Fanari
Membro del Collaboration Group
;
Federico Zorzi;
2023-01-01

Abstract

Numeracy, the ability to understand and use numbers and basic numerical concepts, has significant implications throughout a person's life. Like other cognitive abilities, numeracy tends to decline with age (1), and this decline can be a vulnerability factor for the elderly when it comes to solving everyday tasks (2). The reasons behind this decline with age are still not fully understood. However, gaining insight into this phenomenon could have important implications for distinguishing between normal and pathological aging, as well as for designing environments effective for elderly. Studies have shown that numerical cognition involves a highly-integrated brain network comprising frontal and parietal cortices, with particular importance placed on the intraparietal sulcus and the fusiform gyrus (3). It is possible to hypothesize that a functional impairment of these areas due to aging leads to the presence of dyscalculia. In this study, we employed a parity judgment task to investigate variations in number cognition between older and younger subjects. Since numeracy is associated with both symbolic and non-symbolic number representation, the task involved three different numerical formats: Arabic digits, finger representations, and dots. Twenty-eight healthy subjects participated in the study: 14 young participants (64.28% female, mean age: 24.64±3.67) and 14 older participants (42.8% female, mean age: 70.57±4.34). EEG data were recorded using an actiCHamp Plus amplifier (Brain Products, GmbH) with a 64-electrode setup based on the actiCap 10–20 system (Brain Products, GmbH). Stimuli were presented using E-Prime 3.0 (PST, USA), and responses were recorded using a Chronos device (PST, USA). The EEG data were analyzed in Matlab (MathWorks, USA) for time/frequency analysis and source identification. To account for the absence of individual MRI scans, pseudo-individual anatomies were created by adapting a template MRI (ICBM152) using digitized head points obtained with a Polhemus Fastrak (Polhemus, USA). Our findings reveal a discrepancy in the activation levels of all the primary cortical areas involved in numerical cognition between the young and old groups, with a general reduction in activation and increased latency observed in the latter group. In the same group, numerical stimuli also induce a wider cortical response. Interestingly, among non-symbolic number representations, dots induce the lowest activation of the parietal cortex in the elderly. We conclude that the reduced activity of the main cortical areas may contribute to the physiological decay in numeracy skills in the elderly and that the recruitment of other cortical areas may serve as a compensatory mechanism.
2023
Numeracy, aging, symbolic number representation, non-symbolic number representation
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/429485
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact