Learning & Perception 

Abstract: The role of the basal ganglia in cognition is still uncertain. This case study investigates the partial neuropsychological profile of a 20-year-old patient with a perinatal left putaminal lesion. This pathology is relatively rare and little is known of its cognitive effects. The focuses of our neuropsychological assessment were working memory, executive functions, analysis of spontaneous speech and implicit skill learning. The patient's executive functions did not attain the normal range, and working memory was also partially impaired. In addition, the temporal features of her speech revealed an increased pause/signal time ratio. Finally, in an implicit skill learning task, the patient showed general motor skill learning, but no sequence specific learning. Together these findings suggest that the frontal/subcortical circuit between the putamen and frontal motor areas plays a role in higher cognitive processing such as executive functions, working memory, as well as in first-order sequence learning.

Abstract: Sound sources often emit trains of discrete sounds, such as a series of footsteps. Previously, two different principles have been suggested for how the human auditory system binds discrete sounds together into perceptual units. The feature similarity principle is based on linking sounds with similar characteristics over time. The predictability principle is based on linking sounds that follow each other in a predictable manner. The present study compared the effects of these two principles. Participants were presented with tone sequences and instructed to continuously indicate whether they perceived a single coherent sequence or two concurrent streams of sound. We investigated the influence of separate manipulations of similarity and predictability on these perceptual reports. Both grouping principles affected perception of the tone sequences, albeit with different characteristics. In particular, results suggest that whereas predictability is only analyzed for the currently perceived sound organization, f...

Abstract: Perceptual organization (PO) impairments have been repeatedly demonstrated in schizophrenia. The extent to which these impairments can be reduced or eliminated, however, has received less attention, and evidence on this issue has not been previously reviewed. The literature suggests that whether normal experience-dependent change in perceptual organization occurs in schizophrenia depends on factors such as: stimulus grouping strength, extent of practice, type of cues upon which top-down feedback can be generated, and patient characteristics (trait and state). Therefore, the purpose of this paper is to review and synthesize the available evidence on plasticity and other forms of change in PO in schizophrenia, and to relate it to current data and theories on plasticity, including perceptual learning (PL) in healthy people. This can clarify the computational and neural mechanisms involved in experience-dependent and state-related aspects of PO in schizophrenia, and also contribute to a greater under...

Abstract: The majority of individuals with dyslexia and additional learning difficulties (D-LDs) also perform poorly on many simple auditory discrimination tasks. We now trained a group of D-LD teenagers on a series of auditory tasks and assessed their pattern of auditory improvement as well as their generalization to reading related tasks. We found that the performance of most D-LD participants quickly improved and reached the level of the general age matched population. Moreover, their pattern of learning specificity (e.g. no transfer from frequency to duration discriminations) was also similar to that previously observed in the general population. When assessed with a battery of verbal tasks that they initially performed poorly, a pattern of specific transfer was observed. Performance on verbal memory tasks improved to peer level, whereas performance on reading and non-verbal cognitive tasks did not. These findings suggest that D-LDs’ mechanisms of long-term learning are adequate. Moreover, perceptual learning can be used as a tool for improving general working memory skills, whose underlying mechanisms seem to be shared by simple tones and complex speech sounds.