Tonotopic Gradients in Human Primary Auditory Cortex: Concurring Evidence From High-Resolution 7 T and 3 T fMRI

Abstract

The tonotopic representations within the primary auditory cortex (PAC) have been successfully mapped with ultra-high field fMRI. Here, we compared the reliability of this tonotopic mapping paradigm at 7 T with 1.5 mm spatial resolution with maps acquired at 3 T with the same stimulation paradigm, but with spatial resolutions of 1.8 and 2.4 mm. For all subjects, the mirror-symmetric gradients within PAC were highly similar at 7 T and 3 T and across renderings at different spatial resolutions; albeit with lower percent signal changes at 3 T. In contrast, the frequency maps outside PAC tended to suffer from a reduced BOLD contrast-to-noise ratio at 3 T for a 1.8 mm voxel size, while robust at 2.4 mm and at 1.5 mm at 7 T. Overall, our results showed the robustness of the phase-encoding paradigm used here to map tonotopic representations across scanners.

Spatial plasticity of the auditory cortex in single‐sided deafness

“…Orderly representation of frequency preference to tonal stimuli across the auditory cortical surface, a functional organization principle of the lemniscal system referred to as tonotopicity, has been demonstrated in microelectrode brain mapping studies in monkeys . Tonotopic gradient organization in the human auditory cortex has been confirmed using functional magnetic resonance imaging (fMRI) technology . For a particular cortical hemisphere, contralateral ear input dominance is evidenced by shorter activation latencies and larger amplitudes compared to the ipsilateral ear …”

“…1 Tonotopic gradient organization in the human auditory cortex has been confirmed using functional magnetic resonance imaging (fMRI) technology. 2 For a particular cortical hemisphere, contralateral ear input dominance is evidenced by shorter activation latencies and larger amplitudes compared to the ipsilateral ear. 3,4 Otologic disease, degeneration, or trauma can disrupt paired function of the two ears.…”

Early Blindness Shapes Cortical Representations of Auditory Frequency within Auditory Cortex

“…Anterior and posterior borders were drawn along the outer high-frequency representations of the tonotopic maps, and lateral and medial borders were conservatively drawn to include only the medial two-thirds of Heschl's gyrus. Although this ROI selection method cannot isolate auditory core from auditory belts areas that share the same tonotopic gradients, it does provide a consistent PAC definition for individual subjects across distinct acquisition and stimulus types (Da Costa et al, 2015;Thomas et al, 2015).…”

Recent applications of UHF‐MRI in the study of human brain function and structure: a review

“…While there are many studies demonstrating benefits from the use of UHF in a range of brain regions (for example: occipital cortex , motor cortex , auditory cortex , amygdala , hippocampus , cerebellum , or more extended brain regions ), the number of publications with a purely neuroscientific objective has been rather limited until very recently (Fig. ).…”