Differential involvement of the anterior and posterior hippocampus, parahippocampus, and retrosplenial cortex in making precise judgments of spatial distance and object size for remotely acquired memories of environments and objects.

The hippocampus is known to support processing of precise spatial information in recently learned environments. It is less clear, but crucial for theories of systems consolidation, to know whether it also supports processing of precise spatial information in familiar environments learned long ago and whether such precision extends to objects and numbers. In this fMRI study, we asked participants to make progressively more refined spatial distance judgments among well-known Toronto landmarks (whether landmark A is closer to landmark B or C) to examine hippocampal involvement.

Neural Correlates of Speech Segregation Based on Formant Frequencies of Adjacent Vowels.

The neural substrates by which speech sounds are perceptually segregated into distinct streams are poorly understood. Here, we recorded high-density scalp event-related potentials (ERPs) while participants were presented with a cyclic pattern of three vowel sounds (/ee/-/ae/-/ee/). Each trial consisted of an adaptation sequence, which could have either a small, intermediate, or large difference in first formant (Δf) as well as a test sequence, in which Δf was always intermediate.

No evidence of somatotopic place of articulation feature mapping in motor cortex during passive speech perception.

The motor theory of speech perception has experienced a recent revival due to a number of studies implicating the motor system during speech perception. In a key study, Pulvermüller et al. (2006) showed that premotor/motor cortex differentially responds to the passive auditory perception of lip and tongue speech sounds.

Distributed neural representations of phonological features during speech perception.

A fundamental goal of the human auditory system is to map complex acoustic signals onto stable internal representations of the basic sound patterns of speech. Phonemes and the distinctive features that they comprise constitute the basic building blocks from which higher-level linguistic representations, such as words and sentences, are formed. Although the neural structures underlying phonemic representations have been well studied, there is considerable debate regarding frontal-motor cortical contributions to speech as well as the extent of lateralization of phonological representations within auditory cortex.