Rapid recalibration of temporal order judgements: Response bias accounts for contradictory results

Recent history influences subsequent perception, decision‐making and motor behaviours. In this article, we address a discrepancy in the effects of recent sensory history on the perceived timing of auditory and visual stimuli. In the synchrony judgement (SJ) task, similar timing relationships in consecutive trials seem more synchronous (i.e. less like the repeated temporal order). This effect is known as rapid recalibration and is consistent with a negative perceptual aftereffect. Interestingly, the opposite is found in the temporal order judgement (TOJ) task (positive rapid recalibration). We aimed to determine whether a simple bias to repeat judgements on consecutive trials (choice‐repetition bias) could account for the discrepant results in these tasks. Preliminary simulations and analyses indicated that a choice‐repetition bias could produce apparently positive rapid recalibration in the TOJ and not the SJ task. Our first experiment revealed no evidence of rapid recalibration of TOJs, but negative rapid recalibration of associated confidence. This suggests that timing perception was rapidly recalibrated, but that the negative recalibration effect was obfuscated by a positive bias effect. In our second experiment, we experimentally mitigated the choice‐repetition bias effect and found negative rapid recalibration of TOJs. We therefore conclude that timing perception is negatively rapidly recalibrated, and this is observed consistently across timing tasks. These results contribute to a growing body of evidence that indicates multisensory perception is constantly undergoing recalibration, such that perceptual synchrony is maintained. This work also demonstrates that participants’ task responses reflect judgements that are contaminated by independent biases of perception and decision‐making.     

Diffusion tensor MRI assesses corticospinal tract damage in ALS.

BACKGROUND: A number of neurophysiologic and neuroimaging techniques have been evaluated in the research setting to assess upper motor neuron (UMN) damage in ALS. Changes in tissue structure in the CNS modify the diffusional behavior of water molecules, which can be detected by diffusion tensor MRI. OBJECTIVES: To explore the hypothesis that degeneration of the motor fibers in ALS would be reflected by changes in the diffusion characteristics of the white matter fibers in the posterior limb of the internal capsule and that these changes could be detected by diffusion tensor MRI. METHODS: We studied 22 patients with El Escorial definite, probable, or possible ALS-11 with limb onset (mean age 54.5 +/- 10.7 years) and 11 with bulbar onset (mean age 49.6 +/- 11.7 years)-and compared them with 20 healthy, age-matched controls (mean age 46.0 +/- 12.6 years). We assessed central motor conduction time (CMCT), threshold to stimulation, and silent period using transcranial magnetic stimulation. Diffusion tensor MRI was performed using a 1.5-T GE Signa system (Milwaukee, WI) fitted with Advanced NMR hardware and software capable of producing echo planar MR images. Data were acquired from seven coronal slices centered to include the posterior limb of the internal capsule. Maps of the mean diffusivity, fractional anisotropy, and T2-weighted signal intensity were generated. RESULTS: There were no differences between the subject groups on measures of CMCT, threshold to stimulation, and silent period. However, the CMCT correlated with clinical measures of UMN involvement. We found a significant increase in the mean diffusivity and reduction in fractional anisotropy along the corticospinal tracts between the three subject groups, most marked in the bulbar-onset group. The fractional anisotropy correlated with measures of disease severity and UMN involvement, whereas the mean diffusivity correlated with disease duration. CONCLUSION: The results support the use of diffusion tensor MRI in detecting pathology of the corticospinal tracts in ALS.     

Evaluation of atypical human immunodeficiency virus immunoblot reactivity in blood donors

Blood donors reactive by enzyme-linked immunosorbent assay for antibody to the human immunodeficiency virus (HIV) who showed atypical patterns of viral core protein reactivity on Western blot were monitored for several months. Characterization of their antibodies was performed by 1) use of recombinant HIV proteins; 2) determination of cross-reactivity to HTLV-I, HTLV-II, and HTLV-IV: 3) assessment of immune status; and 4) identification of potentially interfering autoantibodies. Nineteen of 20 donors maintained the same HIV antibody reactivity throughout the follow-up period; the other donor became fully antibody-positive. Eighteen of 20 donors' sera showed clear reactivity with HIV recombinant core proteins. Ten of 19 donor samples demonstrated cross-reactivity to HTLV-IV; 3 of these 10 also cross-reacted with HTLV-I. The immune status of all donors was normal, although the medical histories and HLA antibody screens suggested possible autoimmune reactivity in 9 of 18 donors. During follow-up interviews, three donors reported possible risk factors for HIV infection that had not been acknowledged at the time of blood donation. We conclude that exclusion of donors with these atypical serologic test results is warranted while further studies to determine significance are being conducted.     

Growth factors and determinants of wound repair

The application of contemporary biochemical, analytical, and production technology have, in part, clarified the physiologic processes and identified many new factors active in wound repair. A restructuring of the sequence of the reparative events for the wound environment followed the identification of an array of hormonal polypeptides and growth factors. Deterrents of the early phases of repair include neoplasms and therapeutic doses of steroidal and cytotoxic agents. The physiological effects of these agents are rapidly reversed following their removal with a resultant enhancement of wound tear strength and wound energy. The use of synthetic growth hormone and recombinant DNA-produced polypeptide may reverse the deleterious wound healing events initiated in the injured and tumor-bearing host.     

Techniques for obtaining the diagnosis of malignant breast lesions

Although fine needle aspiration is an efficacious method for diagnosing the palpable breast cancer, a negative aspirate does not exclude the presence of a malignancy. Open breast biopsy remains the standard of care in diagnosing a malignant breast lesion. All breast biopsies should be planned as if the scar were to be excised by a definitive surgical procedure (either mastectomy or tylectomy). New lesions in the treated breast require immediate biopsy because of the high likelihood of recurrent disease. Preferably, definitive surgery for malignancy should not be delayed more than 2 weeks after biopsy.     

CBRN considerations in a major incident

Chemical, biological, radiological and nuclear (CBRN) hazards may be encountered during any major incident. General considerations include modifications to triage, managing contaminated or contagious casualties, and the identification and appropriate management of intoxicated/infected/irradiated/injured casualties. In dealing with chemical incidents, characteristics such as toxicity, latency and persistency need to be understood in order to manage casualties appropriately in terms of triage category, life-saving interventions and assessment of contamination risk to responders. Biological agents can be differentiated into live agents (bacteria, viruses and fungi) and toxins. Live agent characteristics and management depend on pathogenicity, virulence, lethality, infectivity and transmissibility, whereas toxins are treated similarly to chemical agents. Radiological and nuclear hazards are managed similarly and may cause irradiation, contamination (external and internal) or a combination with or without trauma. A generic and structured approach is advised to deal with all major incidents including those with a suspected of confirmed CBRN hazard. All healthcare professionals that may be involved in the response to such an incident need to be familiar with the principles of CBRN incident management and of CBRN casualty management as described in this article.     

Characterization of intestinal invasion by Salmonella typhimurium and Salmonella dublin and effect of a mutation in the invH gene.

The relative levels of invasiveness of two bovine isolates each of Salmonella typhimurium and Salmonella dublin and of invH mutants of S. typhimurium were determined in MDCK and Int 407 cultured-cell assays and in bovine ileal loops. S. dublin was found to be significantly less invasive in cultured cells than S. typhimurium, but this difference was not observed in bovine intestines. The invH mutants exhibited a significant reduction in invasion in both cultured cells and bovine intestines. The invasive phenotypes of the strains were confirmed by fluorescent microscopy and scanning and transmission electron microscopy. The wild-type strains were observed in the laminae propriae of the intestinal villi, while in contrast the invH mutants were generally associated with the enterocyte layer. The degree of damage in the bovine ileum was related to the magnitude of the invasion. There was no difference in the amount of S. typhimurium or S. dublin recovered from the bovine ileum either with or without Peyer's patches 3 h after inoculation of the loop.