Search Abstracts | Symposia | Slide Sessions | Poster Sessions
Decreased functional connectivity to the pre-supplementary motor area underlying serial order memory impairment in a case of transcortical motor aphasia
Poster Session D, Saturday, September 13, 5:00 - 6:30 pm, Field House
Takuya Nakayama1, Marta Pijanowska2, Shinya Uchida1,3; 1International University of Health and Welfare, 2Rikkyo University, 3Juntendo University
【Background and Objective】 The left pre-supplementary motor area (pre-SMA) contributes to the processing of sequential linguistic information (Cona, 2017) together with the regions involved in verbal working memory - the left opercular part of the inferior frontal gyrus (Broca’s area) and the left supramarginal gyrus (the phonological loop), and the left middle frontal gyrus (the central executive). Disconnection between these regions may contribute to deficits in order memory, but the neural basis of such impairment remains unclear. In this study, we investigated functional connectivity in a patient with transcortical motor aphasia (TCMA) who exhibited order memory impairment following a lesion near the left pre-SMA. 【Participant】 The participant (female, 79, right-handed) developed aphasia following subarachnoid hemorrhage and subsequent cerebral infarction. On day 104 post-onset, T2-weighted MRI revealed a hyperintense lesion in the subcortical region of the left superior frontal gyrus. She was diagnosed with mild TCMA. Apraxia of speech was not present, but spontaneous speech was non-fluent, characterized by a reduced speech rate and shortened phrase length. Auditory comprehension and repetition abilities were largely preserved. In verbal working memory assessment, a selective impairment in order memory was observed: performance on an item recognition task was comparable to that of healthy controls, whereas performance on an order recognition task was significantly reduced. 【Functional connectivity analysis】 MRI data were acquired on 104th day post-onset using a 3-T MRI scanner (Galan; Toshiba). The fMRI data for resting state functional connectivity analysis were obtained with a GE-EPI sequence (TR, 2500 ms; voxel size, 3.75 ×3.75 ×4 mm3; 20 slices covering the whole brain). A total of 120 scans were carried out. MRI images were preprocessed using CONN software as follows: 1) motion corrected, 2) spatially normalized into the MNI space, 3) spatially smoothed with 9-mm FWHM Gaussian kernel, and 4) temporally band-pass filtered (0.008 - 0.09 Hz). Regions of interest (ROIs) were set on the left pre-SMA (MNI coordinates: MNI-5 6 53), pars opercularis part of Broca’s area (-54 6 18), left supramarginal gyrus (54, -39, 24), and the left middle frontal gyrus (-38, 44, 26). The correlation coefficients between ROIs were calculated and compared with data derived from healthy subjects database (NeuroSynth) (threshold < .20). 【Results】 The patient showed reduced functional connectivity between the left pre-SMA and any of the other ROIs. However, functional connectivity between the left IFG and the left supramarginal and middle frontal gyri was preserved. 【Discussion】 In contrast to the healthy cohort, where the left pre-SMA exhibits functional connectivity with the left IFG, supramarginal gyrus, and middle frontal gyrus, the patient displayed decreased connectivity between these areas. However, the functional connectivity normally observed between the left IFG and both the supramarginal and middle frontal gyri was preserved. The decrease of functional connectivity between the left pre-SMA and both the left IFG and the middle frontal gyrus suggests a potential neural basis for the patient’s impaired order memory.
Topic Areas: Disorders: Acquired,