The fundamental problem in audition is determining the mechanisms required by the brain to transform an unlabelled mixture of auditory stimuli into coherent perceptual representations. This process is called auditory-scene analysis. The perceptual representations that result from auditory-scene analysis are formed through a complex interaction of perceptual grouping, attention, categorization a...

Congenital deafness not only affects the development of the auditory cortex, but also the interrelation between the visual and auditory system. For example, congenital deafness leads to visual modulation of the deaf auditory cortex in the form of cross-modal plasticity. Here we asked, whether congenital deafness additionally affects auditory modulation in the visual cortex. We demonstrate that ...

The human auditory cortex includes several interconnected areas. A better understanding of the mechanisms involved in auditory cortical functions requires a detailed knowledge of neuronal connectivity between functional cortical regions. In human, it is difficult to track in vivo neuronal connectivity. We investigated the interarea connection in vivo in the auditory cortex using a method of dir...

Previous neuroimaging studies of perceptual priming have reported priming-related decreases in the extrastriate cortex. However, because these experiments have used visual stimuli, it is unclear whether the observed decreases are associated speciacally with some aspect of visual perceptual processing or with more general aspects of priming. We studied withinand cross-modality priming using an a...

The apparently effortless identification of speech is one of the human auditory cortex' finest and least understood functions. This is partly due to difficulties to tease apart effects of acoustic and phonetic attributes of speech sounds. Here we present evidence from magnetic source imaging that the auditory cortex represents speech sounds (such as [g] and [t]) in a topographically orderly fas...

Sensory cortices of individuals who are congenitally deprived of a sense can exhibit considerable plasticity and be recruited to process information from the senses that remain intact. Here, we explored whether the auditory cortex of congenitally deaf individuals represents visual field location of a stimulus-a dimension that is represented in early visual areas. We used functional MRI to measu...

Spectral analysis of acoustic stimuli occurs in the auditory periphery (termed frequency selectivity) as well as at the level of auditory cortex (termed frequency specificity). Frequency selectivity is commonly investigated using an auditory filter model, while frequency specificity is often investigated as neural adaptation of the N1 response in electroencephalography (EEG). However, the effec...

The auditory cortex of the rat is becoming an increasingly popular model system for studies of experience-dependent receptive field plasticity. However, the relative position of various fields within the auditory core and the receptive field organization within each field have yet to be fully described in the normative case. In this study, the macro- and micro-organizational features of the aud...

Brain injury is a serious clinical problem. The success of recovery from brain injury involves functional compensation in the affected brain area. We are interested in general mechanisms that underlie compensatory plasticity after brain damage, particularly when multiple brain areas or multiple modalities are included. In this thesis, I studied the function of auditory cortex after recovery fro...

Ten monkeys were trained on two auditory discrimination problems of different levels of difficulty plus one visual pattern discrimination task. Bilateral conical ablations were made of either the ventral portion of the superior tem· poral gyrus to the depth of the superior temporal sulcus in the midtemporal region, or of the primary auditory projection cortex of the supratemporal plane extendin...