Purpose: This fMRI study is about modelling the effective connectivity between Heschl’s gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. Materials & methods: Ten healthy male participants were required to listen to white noise stimuli during functional magnetic resonance imaging (fMRI) scans. Statistical parametric mapping (SPM) was used to generate individual and group brain activation maps. For input region determination, two intrinsic connectivity models comprising bilateral HG and STG were constructed using dynamic causal modelling (DCM). The models were estimated and inferred using DCM while Bayesian Model Selection (BMS) for group studies was used for model comparison and selection. Based on the winning model, six linear and six non-linear causal models were derived and were again estimated, inferred, and compared to obtain a model that best represents the effective connectivity between HG and the STG, balancing accuracy and complexity. Results: Group results indicated significant asymmetrical activation (puncorr < 0.001) in bilateral HG and STG. Model comparison results showed strong evidence of STG as the input centre. The winning model is preferred by 6 out of 10 participants. The results were supported by BMS results for group studies with the expected posterior probability,r = 0.7830 and exceedance probability, φ = 0.9823. One-sample t-tests performed on connection values obtained from the winning model indicated that the valid connections for the winning model are the unidirectional parallel connections from STG to bilateral HG (p < 0.05). Subsequent model comparison between linear and non-linear models using BMS prefers non-linear connection (r = 0.9160, φ = 1.000) from which the connectivity between STG and the ipsi- and contralateral HG is gated by the activity in STG itself. Conclusion: We are able to demonstrate that the effective connectivity between HG and STG while listening to white noise for the respective participants can be explained by a non-linear dynamic causal model with the activity in STG influencing the STG-HG connectivity non-linearly.

Introduction: Health care workers (HCW) are constantly exposed to blood-borne illnesses through needle stick injuries (NSI). Despite the increasing trend of NSI, evidence regarding the actual practice of universal precautions among these HCWs is lacking. This study assessed the practice of universal precautions towards prevention of NSI among HCWs in a teaching hospital setting. Methods: This cross-sectional survey involved a newly-designed self-completed questionnaire assessing demographic data, exposure to NSI and practice of universal precautions. Questionnaires were distributed to every ward and completed questionnaires were collected after a period of 7 days. Results: A total of 215 HCWs responded to the survey. 35.8% were exposed to bodily fluid, with 22.3% had NSI in the last 12 months. Blood taking was the commonest procedure associated with NSI. Of practices of universal precautions, recapping needle and removing needle from syringe were still wrongly practiced by the HCWs assessed. Conclusion: NSI among HCW are still common despite the introduction of universal precautions in our hospital. Incorrect practices in handling sharps should be looked into in order to reduce the incidence of blood-borne illnesses through NSI in the hospital.