Dynamics underlying auditory‐object‐boundary detection in primary auditory cortex

Abstract

Auditory object analysis requires the fundamental perceptual process of detecting boundaries between auditory objects. However, the dynamics underlying the identification of discontinuities at object boundaries are not well understood. Here, we employed a synthetic stimulus composed of frequencymodulated ramps known as 'acoustic textures', where boundaries were created by changing the underlying spectrotemporal statistics. We collected magnetoencephalographic (MEG) data from human volunteers and observed a slow (<1 Hz) post-boundary drift in the neuromagnetic signal. The response evoking this drift signal was source localised close to Heschl's gyrus (HG) bilaterally, which is in agreement with a previous functional magnetic resonance imaging (fMRI) study that found HG to be involved in the detection of similar auditory object boundaries. Time-frequency analysis demonstrated suppression in alpha and beta bands that occurred after the drift signal.

Sustained responses and neural synchronization to amplitude and frequency modulation in sound change with age

“…The sustained response was also sensitive to amplitude and frequency modulations. This is consistent with previous work demonstrating a sustained response to low-frequency amplitude and frequency modulations in sounds (Herrmann and Johnsrude, 2018; Herrmann et al, 2019), and more generally with an increasing body of work showing that temporally regular patterns elicit a sustained neural response (Barascud et al, 2016; Sohoglu and Chait, 2016; Teki et al, 2016; Southwell et al, 2017; Southwell and Chait, 2018; Dheerendra et al, 2021; Herrmann et al, 2021). Similar to neural synchronization, the sustained response was larger for frequency modulations and amplitude-frequency modulations compared to amplitude modulations (Figure 6).…”

“…The sustained response is an ultralow-frequency response (i.e., a constant or slowly drifting offset) elicited by the occurrence of a temporally regular pattern in a sound. A sustained response has been demonstrated in response to repeated sets of pure tones in longer sequences of tones (Barascud et al, 2016; Southwell et al, 2017; Herrmann and Johnsrude, 2018; Southwell and Chait, 2018; Herrmann et al, 2022), coherent frequency changes in multi-tone chords (Teki et al, 2016; Dheerendra et al, 2021), and complex sounds made of isochronous tone sequences (Sohoglu and Chait, 2016). A sustained response has also been observed for amplitude (Ross et al, 2002; Herrmann et al, 2019) and frequency modulations in sounds (Herrmann and Johnsrude, 2018), and for isochronously presented clicks or vowels compared to irregular presentations (Gutschalk et al, 2002; Gutschalk and Uppenkamp, 2011).…”

Atypical brain responses to 40‐Hz click trains in girls with Rett syndrome: Auditory steady‐state response and sustained wave

“…26,61 Consistent with this, the region that is thought to be the source of SW (the lateral part of Heschl's gyrus) has been associated with detection of boundaries of auditory objects in functional magnetic resonance imaging studies. 62 Amplitude of SW was less pronounced in children with RTT in our study, which points to the impaired perception of global temporal structure. As SW is more pronounced at higher frequencies where pitch is more detectable, 24,63 we can speculate that at 40 Hz, girls with RTT have problems in coding this temporal structure globally as a low pitch via the rate-processing mechanism, which hampers their speech perception.…”

“…when there are several changing patterns of regular stimuli and noise 26,61 . Consistent with this, the region that is thought to be the source of SW (the lateral part of Heschl's gyrus) has been associated with detection of boundaries of auditory objects in functional magnetic resonance imaging studies 62 …”

Sustained responses and neural synchronization to amplitude and frequency modulation in sound change with age

“…The sustained response is an ultralow-frequency response (i.e., a constant or slowly drifting offset) elicited by the occurrence of a temporally regular pattern in a sound. A sustained response has been demonstrated in response to repeated sets of pure tones in longer sequences of tones (Barascud et al, 2016;Southwell et al, 2017;Southwell and Chait, 2018;Herrmann et al, 2022), coherent frequency changes in multitone chords (Teki et al, 2016;Dheerendra et al, 2021), and complex sounds made of isochronous tone sequences (Sohoglu and Chait, 2016). A sustained response has also been observed for amplitude (Ross et al, 2002;Herrmann et al, 2019) and frequency modulations in sounds , and for isochronously presented clicks or vowels compared to irregular presentations (Gutschalk et al, 2002;Gutschalk and Uppenkamp, 2011).…”