Abstract
Auditory evoked fields (AEFs) are commonly studied, yet their underlying neural mechanisms remain poorly understood. Here, we used the biophysical modelling software Human Neocortical Neurosolver (HNN) whose foundation is a canonical neocortical circuit model to interpret the cell and network mechanisms contributing to macroscale AEFs elicited by a simple tone, measured with magnetoencephalography. We found that AEFs can be reproduced by activating the neocortical circuit through a layer specific sequence of feedforward and feedback excitatory synaptic drives, similar to prior simulation of somatosensory evoked responses, supporting the notion that basic structures and activation patterns are preserved across sensory regions. We also applied the modeling framework to develop and test predictions on neural mechanisms underlying AEF differences in the left and right hemispheres, as well as in hemispheres contralateral and ipsilateral to the presentation of the auditory stimulus. We found that increasing the strength of the excitatory synaptic cortical feedback inputs to supragranular layers simulates the commonly observed right hemisphere dominance, while decreasing the input latencies and simultaneously increasing the number of cells contributing to the signal accounted for the contralateral dominance. These results provide a direct link between human data and prior animal studies and lay the foundation for future translational research examining the mechanisms underlying alteration in this fundamental biomarker of auditory processing in healthy cognition and neuropathology.
Highlights
Brain activity evoked by auditory stimulation has been studied for many decades and remains commonly used in cognitive neuroscience (Wagner et al 2017; Parviainen et al 2019) and clinically relevant (Paulraj et al 2015; Samatra et al 2020)
We focus on interpreting the neural mechanisms generating (1) the Auditory evoked fields (AEFs) waveform in response to a simple auditory tone (Parviainen et al 2019), including the preceding response at 50 ms (P50m)-N100m-P200m sequence, (2) observed differences in AEFs in the right and left hemisphere, and (3) between contralateral and ipsilateral tone presentations
While the laminar organization and exogenous drives simulated in Human Neocortical Neurosolver (HNN) are based on animal work, previous work has shown that the resulting simulations can be applied to human data and support canonical input sequences (Jones et al 2007, 2009; Ziegler et al 2010; Sliva et al 2018; Neymotin et al 2020). Building from this hypothesis, we investigated the observed phenomenon that the AEF recorded over the right hemisphere, and the N100m component, is often larger in amplitude compared to the left AEF (Peronnet et al 1974; Mononen and Seitz 1977; Wolpaw and Penry 1977; Hine and Debener 2007; Howard and Poeppel 2009; Kimura 2011; Shaw et al 2013)
Summary
Brain activity evoked by auditory stimulation has been studied for many decades and remains commonly used in cognitive neuroscience (Wagner et al 2017; Parviainen et al 2019) and clinically relevant (Paulraj et al 2015; Samatra et al 2020). The sequence of neural activation evoked by auditory stimulation can be measured using electroencephalography (EEG) or magnetoencephalography (MEG), and the surface-recorded responses are typically divided into three categories based on their latency. Early responses (within ~ 10 ms) primarily reflect brain stem activity, middle-latency auditory responses (10–50 ms) are thought to reflect processing in thalamocortical structures, and late-latency responses (50–250 ms) are associated with cortical activity (Picton et al 1974). Late latency responses are elicited in the primary auditory cortex and surrounding areas and typically consist of components labelled P50m-N100m-P200m (or P1-N1-P2), which peak at around 50, 100 and 180 ms respectively We use simple pure tones at 1 kHz, which have been shown to produce robust N1 responses and are neutral in terms of linguistic associations, and adopted a paradigm that has been successfully used to evidence the fundamental response properties of the human auditory processing pathway (Mäkelä et al 1994; Salmelin et al 1999)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
