Overactivation of fear systems to neutral faces in schizophrenia

Background The amygdala plays a central role in detecting and responding to fear-related stimuli. A number of recent studies have reported decreased amygdala activation in schizophrenia to emotional stimuli (such as fearful faces) compared with matched neutral stimuli (such as neutral faces). We investigated whether the apparent decrease in amygdala activation in schizophrenia could actually derive from increased amygdala activation to the neutral comparator stimuli. Methods Nineteen patients with schizophrenia and 24 matched control participants viewed pictures of faces with either fearful or neutral facial expressions, and a baseline condition, during functional magnetic resonance imaging scanning. Results Patients with schizophrenia showed a relative decrease in amygdala activation to fearful faces compared with neutral faces. However, this difference resulted from an increase in amygdala activation to the neutral faces in patients with schizophrenia, not from a decreased response to the fearful faces. Conclusions Patients with schizophrenia show an increased response of the amygdala to neutral faces. This is sufficient to explain their apparent deficit in amygdala activation to fearful faces compared with neutral faces. The inappropriate activation of neural systems involved in fear to otherwise neutral stimuli may contribute to the development of psychotic symptoms in schizophrenia

Temporal processing in English-speaking and Chinese-speaking dyslexic children

Dyslexia is a developmental disorder characterised by difficulties in reading acquisition in a context of appropriate tuition, socio-cultural opportunities and normal intelligence. A large amount of research has been carried out in the attempt to understand the biological and cognitive causes of dyslexia but to date no unified theory has been finalised. Recent studies have suggested that auditory temporal sequencing abilities might be played a part in skilled reading acquisition. The results of these studies, however, are not unanimous, and replication success has been limited. A further controversial point for the auditory temporal deficit theory is whether it would be able to account for the presence of dyslexia in languages that rely more heavily on logographic processing rather than auditory processing, such as Chinese. The aim of this dissertation was to explore the role of auditory temporal processing skills in reading acquisition using a cross-cultural and developmental approach. The results of the different experiments found no support for a pervasive role of temporal processing skills in reading acquisition in both English-and Chinese speaking samples. Differential levels of performance achievement were seen in dyslexic children in both languages, and also in normal development. Reading skills and temporal processing skills appeared to improve as function of increased age. As the temporal processing tasks used in these studies loaded heavily on working memory, further testing of this latter function showed that working memory skills did not account for the differences between the groups. In conclusion, these studies have contributed to clarify that temporal processing abilities do not play a major role in reading achievement and indicate that no current interpretation appears to be able to account for the variety of symptoms demonstrated by dyslexic children and adults as well as dyslexia in different languages.EThOS - Electronic Theses Online ServiceGBUnited Kingdo