Background: Schizophrenia is characterized by severe working memory (WM) deficits. A possible neural mechanism of such cognitive deficits is the disruption in excitation-inhibition balance in the prefrontal cortex. Our prefrontal network model of spatial WM predicts 2 behavioral consequences of such disinhibition: 1) increased variability of the memory trace over time, reducing the precision of stored information and 2) decreased ability to filter out distractors. We tested these predictions using behavioral data from early course schizophrenia patients and healthy matched healthy comparison subjects (HCS). HCS also underwent an NMDA antagonist (ketamine) infusion, a pharmacological model of schizophrenia hypothesized to induce disinhibition. Methods: Participants were asked to remember the position of circles. After a 10s delay participants used a high-sensitivity joystick to indicate the remembered location. In a distractor task, an additional circle appeared during the delay that participants ignored. Tasks were also performed in the fMRI scanner where controls underwent an infusion of saline or ketamine. Results: Findings largely follow model predictions. Compared to HCS, patients exhibit increased variance and less precision in the delay task but not in the control motor task, showing a specific WM deficit. Patients also show increased distractibility, especially for distracters at specific spatial locations. A similar pattern of results emerges with ketamine. HCS display more variable results compared to baseline and become susceptible to distraction. Conclusions: These preliminary findings show promising support for disinhibition as a neural model of WM deficits in schizophrenia and ketamine as a suitable pharmacological model of these deficits.
B.03 Paper at an international scientific conference
COBISS.SI-ID: 55532898Doctoral work addresses the question of impairment of visual working memory (VWM) in patients with Parkinson's disease (PD) and the effect of dopaminergic therapy in PD patients and dopaminergic modulation in healthy subjects on the processes of encoding, maintenance and filtering of (i)relevant information in VWM. Results do not reveal significant changes in either behavioral results or neurophysiological correlates of VWM as a result of either dopaminergic therapy or modulation, which attests to a relative robustnest of VWM and opens new questions regarding the role of dopaminergic system in the ability to filter and maintain information in VWM.
D.09 Tutoring for postgraduate students
COBISS.SI-ID: 55263330Working memory is a system that temporarily stores and manipulates information that is needed to perform a current task. The most widely accepted, multi-component model of Baddeley and Hitch supposes that working memory is composed of various systems, one of them being the visuospatial sketchpad, which is responsible for storing and manipulating visual and spatial information. A number of authors subdivide it further into separate visual and spatial component. Vogel with his colleagues developed a visuospatial working memory task over the years, where they monitor working memory load by means of EEG. The question how much is a successful performance of the task dependent on visual and spatial component of working memory still remains. A previous study exposed an additional problem of choosing the right interference task that would allow us to distinguish between visual and spatial working memory load. The purpose of this thesis was to examine the efficacy of different interference tasks of visual and spatial working memory in the tasks of spatial and visual memory span. In the study took part 25 participants. Their task was to solve a task of visual and spatial memory span in which they had to reconstruct a matrix of two coloured fields or repeat a sequence of presented stimuli after a short break. In the time of the break we used one of four visual interference tasks of one of four spatial interference tasks or in one condition, no interference. For the realization of the experiment we used a computer and E-prime software. We made a hypothesis, that all interference tasks we used will be effective. That means that the visual interference tasks will disturb visual task of memory span more than the task of spatial span and that the spatial interference task will disturb spatial task of memory span more than visual memory span task. The analysis of the results revealed, that there is a relevant difference in visual and spatial memory span task only in two conditions of visual interference tasks: judgment of colour and judgment of symmetry. The efficiency of the other interference tasks we used was not proven (black and white movement, colour movement, dynamic visual noise, typing of a sequence, spatial sound determination, movement distinction). The results of the study are important for better understanding of the structures that Vogel's tasks is measuring.
D.10 Educational activities
COBISS.SI-ID: 54091874