Combined fMRI region- and network-analysis reveal new insights of top-down modulation of bottom-up processes in auditory laterality
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https://hdl.handle.net/10037/24615Date
2022-01-18Type
Journal articleTidsskriftartikkel
Peer reviewed
Author
Kazimierczak, Katarzyna; Craven, Alexander R.; Ersland, Lars; Specht, Karsten; Dumitru, Magda L.; Sandøy, Lydia B.; Hugdahl, KennethAbstract
Dichotic listening along with the right-ear advantage (REA) has been a standard method
of investigating auditory laterality ever since it was first introduced into neuropsychology
in the early 1960s. Beginning in the 1980s, authors reported that it was possible to
modulate the bottom-up driven perceptual REA by instructing subjects to selectively
attend to and report only from the right or left ear. In the present study, we investigated
neuronal correlates of both the bottom-up and top-down modulation of the REA
through two fMRI analysis approaches: a traditional region approach and a network
connectivity approach. Blood-Oxygenation-Level-Dependent (BOLD) fMRI data were
acquired while subjects performed the standard forced-attention paradigm. We asked
two questions, could the behavioral REA be replicated in unique brain markers, and
second if the profound instruction-induced modulation of the REA found in behavioral
data would correspond to a similar modulation of brain activation, both region- and
network-specific modulations. The subjects were 70 healthy adult right-handers, about
half men and half women. fMRI data were acquired in a 3T MR scanner, and the
behavioral results replicated previous findings with a REA in the non-forced (NF) and
forced-right (FR) conditions, and a tendency for a left-ear advantage (LEA) in the FLcondition. The fMRI data showed unique activations in the speech perception areas
of the left temporal lobe when directly contrasted with activations in the homologous
right side. However, there were no remaining unique activations when the FR- and
FL-conditions were contrasted against each other, and with the NF-condition, using
a conservative significance thresholding. The fMRI results are conceptualized within a
network connectivity frame of reference, especially with reference to the extrinsic mode
network (EMN). The EMN is a generalized task-positive network that is upregulated
whenever the task demands exceed a certain threshold irrespective of the specifics
and demands of the task. This could explain the similarity of activations for the FR- and
FL-conditions, despite the clear differences in behavior.
Citation
Kazimierczak, Craven, Ersland, Specht, Dumitru ML, Sandøy LB, Hugdahl. Combined fMRI region- and network-analysis reveal new insights of top-down modulation of bottom-up processes in auditory laterality. Frontiers in Behavioral Neuroscience. 2022;15Metadata
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