Affiliations: Department of Radiology, Stanford University,
Stanford, CA 94305, USA | Neurosciences Program, Stanford University, Stanford,
CA 94305, USA | Department of Neurology, Johns Hopkins University,
Baltimore, MD 21205, USA
Note: [] Corresponding author: John E. Desmond, Department of Neurology,
Division of Cognitive Neuroscience, The Johns Hopkins Hospital, Reed Hall
East – 2, 1620 McElderry Street, Baltimore, MD 21205, USA. Tel.: +1 410 614
3040; Fax: +1 410 502 2189; E-mail: dr.jdesmond@gmail.com
Abstract: Phonologically similar items (mell, rell, gell) are more difficult
to remember than dissimilar items (shen, floy, stap), likely because of mutual
interference of the items in the phonological store. Low-frequency transcranial
magnetic stimulation (TMS), guided by functional magnetic resonance imaging
(fMRI) was used to disrupt this phonological confusion by stimulation of the
left inferior parietal (LIP) lobule. Subjects received TMS or placebo
stimulation while remembering sets of phonologically similar or dissimilar
pseudo-words. Consistent with behavioral performance of patients with
neurological damage, memory for phonologically similar, but not dissimilar,
items was enhanced following TMS relative to placebo stimulation. Stimulation
of a control region of the brain did not produce any changes in memory
performance. These results provide new insights into how the brain processes
verbal information by establishing the necessity of the inferior parietal
region for optimal phonological storage. A mechanism is proposed for how TMS
reduces phonological confusion and leads to facilitation of phonological
memory.
Keywords: Transcranial magnetic stimulation (TMS), verbal working memory (VWM), cognitive enhancement, neuroimaging, functional magnetic resonance imaging (fMRI), phonological memory
