fMRI Evidence for a Cortical Hierarchy of Pitch Pattern Processing

Pitch patterns, such as melodies, consist of two levels of structure: a global level, comprising the pattern of ups and downs, or contour; and a local level, comprising the precise intervals that make up this contour. An influential neuropsychological model suggests that these two levels of processing are hierarchically linked, with processing of the global structure occurring within the right hemisphere in advance of local processing within the left. However, the predictions of this model and its anatomical basis have not been tested in neurologically normal individuals. The present study used fMRI and required participants to listen to consecutive pitch sequences while performing a same/different one-back task. Sequences, when different, either preserved (local) or violated (global) the contour of the sequence preceding them. When the activations for the local and global conditions were contrasted directly, additional activation was seen for local processing in right planum temporale and posterior superior temporal sulcus (pSTS). The presence of additional activation for local over global processing supports the hierarchical view that the global structure of a pitch sequence acts as a “framework” on which the local detail is subsequently hung. However, the lateralisation of activation seen in the present study, with global processing occurring in left pSTS and local processing occurring bilaterally, differed from that predicted by the neuroanatomical model. A re-examination of the individual lesion data on which the neuroanatomical model is based revealed that the lesion data equally well support the laterality scheme suggested by our data. While the present study supports the hierarchical view of local and global processing, there is an evident need for further research, both in patients and neurologically normal individuals, before an understanding of the functional lateralisation of local and global processing can be considered established

Cortical Mechanisms for the Segregation and Representation of Acoustic Textures

Auditory object analysis requires two fundamental perceptual processes: the definition of the boundaries between objects, and the abstraction and maintenance of an object's characteristic features. Although it is intuitive to assume that the detection of the discontinuities at an object's boundaries precedes the subsequent precise representation of the object, the specific underlying cortical mechanisms for segregating and representing auditory objects within the auditory scene are unknown. We investigated the cortical bases of these two processes for one type of auditory object, an “acoustic texture,” composed of multiple frequency-modulated ramps. In these stimuli, we independently manipulated the statistical rules governing (1) the frequency–time space within individual textures (comprising ramps with a given spectrotemporal coherence) and (2) the boundaries between textures (adjacent textures with different spectrotemporal coherences). Using functional magnetic resonance imaging, we show mechanisms defining boundaries between textures with different coherences in primary and association auditory cortices, whereas texture coherence is represented only in association cortex. Furthermore, participants' superior detection of boundaries across which texture coherence increased (as opposed to decreased) was reflected in a greater neural response in auditory association cortex at these boundaries. The results suggest a hierarchical mechanism for processing acoustic textures that is relevant to auditory object analysis: boundaries between objects are first detected as a change in statistical rules over frequency–time space, before a representation that corresponds to the characteristics of the perceived object is formed

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

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 frequency modulated ramps known as "acoustic textures", where boundaries were created by changing the underlying spectro-temporal statistics. We collected magnetoencephalographic (MEG) data from human volunteers and observed a slow (<1 Hz) post boundary drift in the neuro-magnetic signal. The response evoking this drift signal was source localized close to Heschl's Gyrus (HG) bilaterally, which is in agreement with a previous 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

The Human Auditory Cortex

XIV, 398 p.online resource

Smart Energy in Haushalten: Technologien, Geschäftsmodelle, Akzeptanz und Wirtschaftlichkeit

Die Digitalisierung des deutschen Energiesystems wird als eine wichtige Voraussetzung für dasGelingen der Energiewende gesehen. Insbesondere im Bereich der Elektrizitätsversorgung kannDigitalisierung die Flexibilitätspotenziale, z. B. für das Verteilnetz, steigern. Dafür sollen klassischeEnergietechnologien (der Erzeugung, Speicherung und Verbraucher) mit Informations- undKommunikationstechnologien (IKT) oder „Internet-of-Things“-Technologien (IoT) zusammenspielen.Auf diese Weise wandelt sich das Energieversorgungssystem beispielsweise im Elektrizitätsbereichvon ei

Smart Energy in Haushalten : Technologien, Geschäftsmodelle, Akzeptanz und Wirtschaftlichkeit

Die Digitalisierung des deutschen Energiesystems wird als eine wichtige Voraussetzung für das Gelingen der Energiewende gesehen. Insbesondere im Bereich der Elektrizitätsversorgung kann Digitalisierung die Flexibilitätspotenziale, z. B. für das Verteilnetz, steigern. Dafür sollen klassische Energietechnologien (der Erzeugung, Speicherung und Verbraucher) mit Informations- und Kommunikationstechnologien (IKT) oder "Internet-of-Things"-Technologien (IoT) zusammenspielen. Auf diese Weise wandelt sich das Energieversorgungssystem beispielsweise im Elektrizitätsbereich von einem unidirektionalen Netz zu einem bidirektionalen Netzwerk, ein sogenanntes Smart Grid. Sowohl Energie als auch energiebezogene Informationen können zwischen Verbrauchern, Netzbetreibern sowie zwischen Energieerzeugungsanlagen und Energiespeichern ausgetauscht werden. In diesem Zusammenhang entwickeln Unternehmen innovative smarte Produkte und Dienstleistungen für private Haushalte, z. B. Smart Home Systeme, Energiemanagementsysteme, Smart Meter, intelligente Beleuchtungssysteme oder sie bieten digitale Dienstleistungen wie z. B. die datenbasierte Fernwartung von Photovoltaik-Anlagen an

Gamma band pitch responses in human auditory cortex measured with magnetoencephalography

We have previously used direct electrode recordings in two human subjects to identify neural correlates of the perception of pitch (Griffiths, Kumar, Sedley et al., Direct recordings of pitch responses from human auditory cortex, Curr. Biol. 22 (2010), pp. 1128–1132). The present study was carried out to assess virtual-electrode measures of pitch perception based on non-invasive magnetoencephalography (MEG). We recorded pitch responses in 13 healthy volunteers using a passive listening paradigm and the same pitch-evoking stimuli (regular interval noise; RIN) as in the previous study. Source activity was reconstructed using a beamformer approach, which was used to place virtual electrodes in auditory cortex. Time-frequency decomposition of these data revealed oscillatory responses to pitch in the gamma frequency band to occur, in Heschl's gyrus, from 60 Hz upwards. Direct comparison of these pitch responses to the previous depth electrode recordings shows a striking congruence in terms of spectrotemporal profile and anatomical distribution. These findings provide further support that auditory high gamma oscillations occur in association with RIN pitch stimuli, and validate the use of MEG to assess neural correlates of normal and abnormal pitch perception

The cortical analysis of speech-specific temporal structure revealed by responses to sound quilts

Speech contains temporal structure that the brain must analyze to enable linguistic processing. To investigate the neural basis of this analysis, we used sound quilts, stimuli constructed by shuffling segments of a natural sound, approximately preserving its properties on short timescales while disrupting them on longer scales. We generated quilts from foreign speech to eliminate language cues and manipulated the extent of natural acoustic structure by varying the segment length. Using functional magnetic resonance imaging, we identified bilateral regions of the superior temporal sulcus (STS) whose responses varied with segment length. This effect was absent in primary auditory cortex and did not occur for quilts made from other natural sounds or acoustically matched synthetic sounds, suggesting tuning to speech-specific spectrotemporal structure. When examined parametrically, the STS response increased with segment length up to ~500 ms. Our results identify a locus of speech analysis in human auditory cortex that is distinct from lexical, semantic or syntactic processes.James S. McDonnell Foundation (Scholar Award