Crossmodal temporal processing acuity impairment aggravates with age in developmental dyslexia

Area of Science:

• Neuroscience
• Developmental Psychology
• Cognitive Science

Background:

• Developmental dyslexia is associated with impaired temporal processing.
• Aging can affect cognitive functions, including temporal acuity.
• Crossmodal temporal processing is vital for integrating sensory information, particularly in reading.

Purpose of the Study:

• To investigate the impact of aging on crossmodal temporal processing in individuals with and without developmental dyslexia.
• To determine if age-related changes in temporal acuity differ between dyslexic and fluent readers.
• To explore the potential link between age-related temporal processing deficits and the underlying causes of dyslexia.

Main Methods:

• A cohort of 39 dyslexic and 40 fluent readers aged 20-59 years participated.
• Six tasks measured cognitive temporal acuity at millisecond levels.
• Tasks included order judgments (audiotactile, visuotactile, audiovisual) and simultaneity/nonsimultaneity detection of stimulus pulses.

Main Results:

• Temporal acuity declined with age in both reading groups.
• Impaired temporal acuity was confirmed in individuals with developmental dyslexia.
• A significant finding was the age-related exacerbation of crossmodal temporal impairment in dyslexic readers.

Conclusions:

• Crossmodal temporal processing deficits in developmental dyslexia worsen with age.
• This age-related exacerbation suggests a pre-existing developmental neuronal deficit, potentially involving magnocells, as an ontogenetic cause of dyslexia.