Attentional blink in patients with multiple sclerosis.

The attentional blink (AB), characterized as a failure to detect a second target following correct identification of a previous target in a rapid serial visual presentation (RSVP), has become a useful measure for investigation of the temporal dynamics of attention. In our previous work, we proposed a two-stage concurrent inhibition model that attributes AB not only to capacity limitations at the central, working memory but also to the lack of proper inhibitory processes, which depend in part on the integrity of white matter. To test the hypothesis that attentional blink can be influenced by the integrity of the white matter, we investigated AB in patients with multiple sclerosis (MS), where the dominant neuropathology is demyelination-related cortical white matter impairments. We tested 22 MS patients and 22 age-matched controls with RSVP task. MS patients were further examined with standard tests of motor functioning (9 Hole Peg Test-9HPT and 8m walking test) and 2 tests of working memory (Paced Auditory Serial Addition Test-PASAT and Digit Ordering test-DOT). On average, MS patients did not show working memory impairments, but greater and longer AB. Our results thus support the hypothesis that one potential mechanism of attentional impairments in MS could be unreliable inhibitory processes. We propose that in MS inhibitory processes depend on white matter integrity, i.e., functional connectivity between the perceptual and working memory modules. Future research should focus on concurrent measurements of neuroanatomical and attentional features of MS patients to further support our findings.