title: Tonotopic representation of loudness in the human cortex.
abstract: A prominent feature of the auditory system is that neurons show tuning to audio frequency; each neuron has a characteristic frequency (CF) to which it is most sensitive. Furthermore, there is an orderly mapping of CF to position, which is called tonotopic organization and which is observed at many levels of the auditory system. In a previous study (Thwaites et al., 2016) we examined cortical entrainment to two auditory transforms predicted by a model of loudness, instantaneous loudness and short-term loudness, using speech as the input signal. The model is based on the assumption that neural activity is combined across CFs (i.e. across frequency channels) before the transform to short-term loudness. However, it is also possible that short-term loudness is determined on a channel-specific basis. Here we tested these possibilities by assessing neural entrainment to the overall and channel-specific instantaneous loudness and the overall and channel-specific short-term loudness. The results showed entrainment to channel-specific instantaneous loudness at latencies of 45 and 100 ms (bilaterally, in and around Heschl's gyrus). There was entrainment to overall instantaneous loudness at 165 ms in dorso-lateral sulcus (DLS). Entrainment to overall short-term loudness occurred primarily at 275 ms, bilaterally in DLS and superior temporal sulcus. There was only weak evidence for entrainment to channel-specific short-term loudness.
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, UK; MRC Cognition and Brain Sciences Unit, Cambridge, UK. Electronic address: acgt2@cam.ac.uk.
authors.forename: Andrew
authors.initials: A
authors.lastname: Thwaites
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, UK. Electronic address: js2251@cam.ac.uk.
authors.forename: Josef
authors.initials: J
authors.lastname: Schlittenlacher
authors.affiliation: MRC Cognition and Brain Sciences Unit, Cambridge, UK. Electronic address: iannimmosmith@gmail.com.
authors.forename: Ian
authors.initials: I
authors.lastname: Nimmo-Smith
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, UK; MRC Cognition and Brain Sciences Unit, Cambridge, UK. Electronic address: wdm10@cam.ac.uk.
authors.forename: William D
authors.initials: WD
authors.lastname: Marslen-Wilson
authors.affiliation: Department of Psychology, University of Cambridge, Cambridge, UK. Electronic address: bcjm@cam.ac.uk.
authors.forename: Brian C J
authors.initials: BC
authors.lastname: Moore
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001302:Audiometry, Speech; D001306:Auditory Pathways / Q000166:cytology / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D002540:Cerebral Cortex / Q000166:cytology / Q000502:physiology*; D005260:Female; D006309:Hearing; D006801:Humans; D008144:Loudness Perception; D015225:Magnetoencephalography; D008297:Male; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D011930:Reaction Time; D013067:Speech Perception; D013997:Time Factors; D055815:Young Adult
keywords: Entrainment; Loudness; Magnetoencephalography; Model expression; Temporal integration; Tonotopy