Talks
Forthcoming talks
Past talks
Where: Centre for Addiction and Mental Health in Toronto, Ontario, Canada; University of Toronto, Ontario, Canada When: 30th May 2006
Published in: Sörös P, Sokoloff LG, Bose A, McIntosh AR, Graham SJ, Stuss DT. Clustered functional MRI of overt speech production. Neuroimage 2006;32(1):376-387. Reprint: http://neuroactivity.org/wp-content/uploads/2006/05/SorosNeuroimage2006.pdf
To investigate the neural network of overt speech production, event-related fMRI was performed in 9 young healthy adult volunteers. A clustered image acquisition technique was chosen to minimize speech-related movement artifacts. Functional images were acquired during the production of oral movements and of speech of increasing complexity (isolated vowel as well as monosyllabic and trisyllabic utterances). This imaging technique and behavioral task enabled depiction of the articulo-phonologic network of speech production from the supplementary motor area at the cranial end to the red nucleus at the caudal end. Speaking a single vowel and performing simple oral movements involved very similar activation of the cortical and subcortical motor systems. More complex, polysyllabic utterances were associated with additional activation in the bilateral cerebellum, reflecting increased demand on speech motor control, and additional activation in the bilateral temporal cortex, reflecting the stronger involvement of phonologic processing.
LikeThe cortical topography of swallowing.
Where: Rotman Research Institute, Baycrest, Toronto, Ontario, Canada; University of Toronto, Toronto, Ontario, Canada When: 21st January 2003, 4pm - 6pm
Published in: Dziewas R, Sörös P, Ishii R, Chau W, Henningsen H, Ringelstein EB, Knecht S, Pantev C. Neuroimaging evidence for cortical involvement in the preparation and in the act of swallowing. Neuroimage. 2003;20(1):135-44.
This study employed whole head magnetoencephalography and synthetic aperture magnetometry to investigate the cortical topography of the preparation and the execution of volitional and reflexive water swallowing and of a simple tongue movement. Concerning movement execution, activation of the mid-lateral primary sensorimotor cortex was strongly lateralized to the left during volitional water swallowing, less strongly lateralized to the left during reflexive water swallowing, and not lateralized at all during tongue movement. In contrast, the preparation for both volitional water swallowing and tongue movement showed a bilateral activation of the primary sensorimotor cortex. No activation was seen prior to reflexive water swallowing. Activation of the left insula and frontal operculum was observed only during both the preparation and the execution of volitional water swallowing. These new findings suggest a left hemispheric dominance for the cortical control of swallowing in humans.
Functional MRI of oropharyngeal air-pulse stimulation.
Where: Dysphagia Research Society 2008
Published in: Sörös P, Lalone E, Smith R, Stevens T, Theurer J, Menon R, Martin R. Functional MRI of oropharyngeal air-pulse stimulation. Neuroscience 2008;153:1300-1308.
Although the posterior oral cavity and oropharynx play a major role in swallowing, their central representation is poorly understood. High-field functional magnetic resonance imaging of the brain was used to study the central processing of brief air-pulses, delivered to the peritonsillar region of the lateral oropharynx, in six healthy adults. Bilateral air-pulse stimulation was associated with the activation of a bilateral network including the primary somatosensory cortex and the thalamus, classic motor areas (primary motor cortex, supplementary motor area, cingulate motor areas), and polymodal areas (including the insula and frontal cortex). These results suggest that oropharyngeal stimulation can activate a bilaterally distributed cortical network that overlaps cortical regions previously implicated in oral and pharyngeal sensorimotor functions such as tongue movement, mastication, and swallowing. The present study also demonstrates the utility of air-pulse stimulation in investigating oropharyngeal sensorimotor processing in functional brain imaging experiments.
Functional brain imaging of swallowing: An activation likelihood meta-analysis.
Where: Dysphagia Research Society 2008
Published in: Sörös P, Inamoto Y, Martin RE. Functional brain imaging of swallowing: An activation likelihood estimation meta-analysis. Hum Brain Mapp. 2008 Dec 23.
A quantitative, voxel-wise meta-analysis was performed to investigate the cortical control of water and saliva swallowing. Studies that were included in the meta-analysis (1) examined water swallowing, saliva swallowing, or both, and (2) reported brain activation as coordinates in standard space. Using these criteria, a systematic literature search identified seven studies that examined water swallowing and five studies of saliva swallowing. An activation likelihood estimation (ALE) meta-analysis of these studies was performed with GingerALE. For water swallowing, clusters with high activation likelihood were found in the bilateral sensorimotor cortex, right inferior parietal lobule, and right anterior insula. For saliva swallowing, clusters with high activation likelihood were found in the left sensorimotor cortex, right motor cortex, and bilateral cingulate gyrus. A between-condition meta-analysis revealed clusters with higher activation likelihood for water than for saliva swallowing in the right inferior parietal lobule, right postcentral gyrus, and right anterior insula. Clusters with higher activation likelihood for saliva than for water swallowing were found in the bilateral supplementary motor area, bilateral anterior cingulate gyrus, and bilateral precentral gyrus. This meta-analysis emphasizes the distributed and partly overlapping cortical networks involved in the control of water and saliva swallowing. Water swallowing is associated with right inferior parietal activation, likely reflecting the sensory processing of intraoral water stimulation. Saliva swallowing more strongly involves premotor areas, which are crucial for the initiation and control of movements.
Age-related changes in cortical auditory processing
Where: University of Western Ontario, London, Ontario, Canada When: 2007
Background
Impaired speech perception is one of the major sequelae of aging. In addition to peripheral hearing loss, central deficits of auditory processing are supposed to contribute to the deterioration of speech perception in older individuals. To test the hypothesis that auditory temporal processing is compromised in aging, auditory evoked magnetic fields were recorded during stimulation with sequences of 4 rapidly recurring speech sounds in 28 healthy individuals aged 20 - 78 years.
Results
The decrement of the N1m amplitude during rapid auditory stimulation was not significantly different between older and younger adults. The amplitudes of the middle-latency P1m wave and of the long-latency N1m, however, were significantly larger in older than in younger participants.
Conclusions
These results suggest that age-related behavioral deficits in auditory temporal processing are not paralleled by changes in the decrement (short-term habituation) of the major auditory evoked component, the N1m wave. The cortical processing of individual sounds, in contrast, was characterized by significantly larger amplitudes of the middle-latency P1m wave in older compared to younger participants.
Add Comment