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Frequency heterogeneity of semantic language perception in auditory cognition.1Department of NMR, All India Institute of Medical Sciences, New Delhi, India
Synopsis
Specificity of semantic cognition to characteristics of audio information is a complex interaction of executive and sensory networks. A 2-back auditory working memory task and audiometric assessments were analysed to study the information processing of semantic cognition. A gPPI analysis with frequency modulation were computed for connectome analysis. Interaction of network with respect to the frequency exhibited significant correlation for modulated frequency domain and no interaction for characteristic frequency domain, which suggest frequency heterogeneity during semantic language processing.
Introduction
Auditory cognition dealing in semantics of words and meaningful sentences is a complex interaction of executive function with sensory perception, and may be interlinked to characteristic nature of information perceived1,2. Association of sound with the cognitive domain remains a complex attribute. We studied the audiological correlation of frequency to information processing domain of auditory cognition.Method
A 2-Back Auditory working memory (AWM) task (single syllable word recorded with duration of 500-1000ms and presented as stimuli with 95db amplification to remain audible in MR scanner) was designed to understand the complex nature of word association to meaningful information while discarding ambiguous stimuli. Study was conducted on healthy volunteers (n=61), after IEC approval, on a 3T MR scanner (Ingenia 3T, M/s Philips). All volunteers were screened for pure tone audiometry (PTA) from 125 Hz to 16kHz and brain stem response (ABR) prior to fMRI study. Data was analysed using gPPI model to elucidate network level interaction associated with the stimuli. PTA response was input as modulation parameter to gPPI model after being orthogonalized to hemodynamic response function.Result
gPPI interaction of network revealed single cluster for memory condition with PTA modulation, salience ACC with salience anterior Insula (r) and salience SMG (r) with F= 3.97, 3.85 with p-FDR=.024, .026 respectively (figure 2a). Frequency specific modulation network exhibited significance for only 2000 and 3000Hz. Saliency SMG (l) revealed interaction with saliency RPFC(l) and sensorimotor(l) with F=8.46, 3.91 and p-FDR= 0.0005, 0.025 respectively. Saliency RPFC(l) displayed interaction with language pSTG(l) with F=5.11 and p-FDR=0.0089. Recall condition in 2-back AWM task revealed network interaction with PTA, as well as intermediate frequency 10-16 kHz (Figure 1a) and 1-3kHz (Figure 1b). In intermediate frequency range 1-3kHz, salience aInsula (l) exhibited interaction with default mode MPFC and salience RPFC (l) with pFWE =0.05. Also, salience RPFC(l)with sensorimotor Lateral(r)with F= 4.09 p=0.021665 and fronto parietal LPFC(l)with dorsal attention IPS(r)F= 3.22 with p=0.047213 and dorsal attention IPS(l) with default mode LP(l) for F= 7.05 with p= 0.001792 (figure 1b). To reduce bias for ambiguous stimuli for 1-3kHz modulation, recall>ambiguous condition was computed with correction for multiple comparisons, and pFWE=0.013 threshold, and interactions were observed between saliency anterior Insula(r) with fronto parietal PPC(r), dorsal attention IPS(r) and language pSTG(r) with fronto parietal PPC(r) (figure 2b).Discussion
Stimuli semantics in 2-back AWM task is frequency specific and also represent a modulated frequency connectome (Figure 1). In memory specific condition, 2000 and 3000 Hz represent single syllable stimuli (in 2-back task) being interpreted within modulation frequency range, but above the stimuli characteristics (audiogram of word range between 400-700 Hz). Salience and language network played crucial role in discarding ambiguous stimuli and memory recall for correct stimuli, which was modulated by executive network 1,3. In recall condition the frequency heterogeneity with interaction of network in upper threshold frequency specific range may be due to scanner noise. Interaction of intermediate frequency range of 1k to 3k Hz with executive, attention and language network during recall>ambiguous condition suggest complexity involved in the interpretation 4,5. Interaction of frequency characteristics of syllable is subdued by modulation of frequency range (which are at higher threshold). This represent the aspect of auditory cognition, where semantic processing of information is associated with modulated frequency attributes.Conclusion
The interaction of cognition network is associated with auditory information. Interaction of auditory cognition at complex semantics is frequency modulated with exclusion of emotion.Acknowledgements
This work was supported by LSRB, DRDO vide grant no. LSRB-295/PEE&BS/2017.References
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