Different stimuli, different spatial codes: a visual map and an auditory rate code for oculomotor space in the primate superior colliculus.

Maps are a mainstay of visual, somatosensory, and motor coding in many species. However, auditory maps of space have not been reported in the primate brain. Instead, recent studies have suggested that sound location may be encoded via broadly responsive neurons whose firing rates vary roughly proportionately with sound azimuth. Within frontal space, maps and such rate codes involve different response patterns at the level of individual neurons. Maps consist of neurons exhibiting circumscribed receptive fields, whereas rate codes involve open-ended response patterns that peak in the periphery. This coding format discrepancy therefore poses a potential problem for brain regions responsible for representing both visual and auditory information. Here, we investigated the coding of auditory space in the primate superior colliculus(SC), a structure known to contain visual and oculomotor maps for guiding saccades. We report that, for visual stimuli, neurons showed circumscribed receptive fields consistent with a map, but for auditory stimuli, they had open-ended response patterns consistent with a rate or level-of-activity code for location. The discrepant response patterns were not segregated into different neural populations but occurred in the same neurons. We show that a read-out algorithm in which the site and level of SC activity both contribute to the computation of stimulus location is successful at evaluating the discrepant visual and auditory codes, and can account for subtle but systematic differences in the accuracy of auditory compared to visual saccades. This suggests that a given population of neurons can use different codes to support appropriate multimodal behavior.

Co-activation of the amygdala, hippocampus and inferior frontal gyrus during autobiographical memory retrieval.

Functional MRI was used to investigate the role of medial temporal lobe and inferior frontal lobe regions in autobiographical recall. Prior to scanning, participants generated cue words for 50 autobiographical memories and rated their phenomenological properties using our autobiographical memory questionnaire (AMQ). During scanning, the cue words were presented and participants pressed a button when they retrieved the associated memory. The autobiographical retrieval task was interleaved in an event-related design with a semantic retrieval task (category generation). Region-of-interest analyses showed greater activation of the amygdala, hippocampus, and right inferior frontal gyrus during autobiographical retrieval relative to semantic retrieval. In addition, the left inferior frontal gyrus showed a more prolonged duration of activation in the semantic retrieval condition. A targeted correlational analysis revealed pronounced functional connectivity among the amygdala, hippocampus, and right inferior frontal gyrus during autobiographical retrieval but not during semantic retrieval. These results support theories of autobiographical memory that hypothesize co-activation of frontotemporal areas during recollection of episodes from the personal past.

The frontal eye field sends predictively remapped visual signals to the superior colliculus

We perceive a stable visual world even though saccades often move our retinas. One way the brain may achieve a stable visual percept is through predictive remapping of visual receptive fields: just before a saccade, the receptive field of many neurons moves from its current location ("current receptive field") to the location it is expected to occupy after the saccade ("future receptive field"). Goldberg and colleagues found such remapping in cortical areas, e.g. in the frontal eye field (FEF), as well as in the intermediate layers of the superior colliculus (SC). In the present study we investigated the source of the SC's remapped visual signals. Do some of them come from the FEF? We identified FEF neurons that project to the SC using antidromic stimulation. For neurons with a visual response, we tested whether the receptive field shifted just prior to making a saccade. Saccadic amplitudes were chosen to be as small as possible while clearly separating the current and future receptive fields; they ranged from 5-30 deg. in amplitude and were directed contraversively. The saccadic target was a small red spot. We probed visual responsiveness at the current and future receptive field locations using a white spot flashed at various times before or after the saccade. Predictive remapping was indicated by a visual response to a probe flashed in the future receptive field just before the saccade began. We found that many FEF neurons projecting to the SC exhibited predictive remapping. Moreover, the remapping was as fast and strong as any previously reported for FEF or SC. It is clear, therefore, that remapped visual signals are sent from FEF to SC, providing direct evidence that the FEF is one source of the SC's remapped visual signals. Because remapping requires information about an imminent saccade, we hypothesize that remapping in FEF depends on corollary discharge signals such as those ascending from the SC through MD thalamus (Sommer and Wurtz 2002).

Variabilidad genética de poblaciones de Melampsora spp. agente causal de la roya del álamo, en la zona del Delta Inferior del río Paraná

En la zona del Delta del Paraná, Argentina, el cultivo de álamo constituye el principal recurso productivo y económico. La roya del álamo, producida por especies de Melampsora spp., es la enfermedad fúngica de mayor importancia económica por su carácter epidemiológico. El cultivo de un limitado número de clones, altamente especializados y ecológicamente inestables, provocan la evolución de distintos patosistemas generando el reemplazo de ciertos clones por otros más resistentes. El objetivo de este trabajo fue estudiar la variabilidad genética molecular de la especie Melampsora, sobre 32 aislamientos de ejemplares pertenecientes a clones de Populus spp. durante los años 2007, 2008 y 2009, utilizando las técnicas de AFLPs y SSRs. La utilización de AFLPs permitió diferenciar 32 fenotipos moleculares, mostrando variabilidad genética en la población, mientras que a partir de la utilización de SSRs se confirmó la presencia de M. medusae y M. larici-populina en la zona de estudio. El análisis de agrupamientos (UPGMA) a partir de AFLPs permitió distinguir la cepa de Populus nigra del resto quedando como unidad aislada, a su vez se pudieron identificaron tres clusters de aislamientos provenientes de Populus deltoides, con tendencia a agruparse por origen genético y origen geográfico. El análisis de AMOVA confirmó las diferencias significativas para dichos agrupamientos. Los resultados del presente estudio confirman la existencia de variabilidad genética para los marcadores

An unusual delayed complication of inferior alveolar nerve block

Systemic and localised complications after administration of local anaesthetic for dental procedures are well recognised. We present two cases of patients with trismus and sensory deficit that arose during resolution of trismus as a delayed complication of inferior alveolar nerve block.

Steroid injection for inferior heel pain: a randomised controlled trial

BACKGROUND:

Plantar fasciitis is a common cause of heel pain. The aim of this study was twofold: to compare steroid injection with placebo injection and to compare ultrasound guided with unguided steroid injection in the management of this condition.

METHODS:

65 patients with inferior heel pain were recruited between November 2008 and June 2011. Heel pain was measured using a visual analogue scale (VAS) at baseline and follow-up 6 and 12 weeks after injection.

RESULTS:

22 patients were randomised to ultrasound guided steroid injection, 21 patients to palpation guided steroid injection and 22 to ultrasound guided placebo injection. There was a significant difference in VAS scores between the groups at 6 and 12 weeks (p=0.018 and p=0.004, respectively). There was a 19.7 (95% CI 2.5 to 37.0) difference in mean VAS scores at 6 weeks between the ultrasound guided steroid group and the placebo group and a 24.0 (95% CI 6.6 to 41.3) difference between the unguided steroid group and the placebo group at 6 weeks. At 12 weeks, the mean difference was 25.1 (95% CI 6.5 to 43.6) and 28.4 (95% CI 11.1 to 45.7) respectively between both steroid injection groups and the placebo group. There was no difference in VAS scores following steroid injection between the ultrasound guided and the unguided groups at either time point. Plantar fascia thickness was significantly reduced after injection in both active treatment groups (p=0.00).

CONCLUSIONS:

In this study, steroid injection showed a clear benefit over placebo at 6 weeks and this difference was maintained at 12 weeks.Trial Registration No ISRCTN79628180 (www.controlled-trials.com).

Morphological consequences of lateral outfracture of the inferior turbinate

Objective: We report three cases of lateral outfracture of the inferior turbinate, which demonstrate a range of changes in the size, position and shape of the inferior turbinate.

Method: During a study of the validity of computer modelling of nasal airflow, computed tomography scans of the noses of patients who had undergone lateral outfracture of the inferior turbinate were collected. The pre-operative scan was compared with the post-operative scan six weeks later.

Results: In one patient, there was only a small lateral displacement of the inferior turbinate. In the other two cases, appreciable reduction in the volume of one inferior turbinate was noted, in addition to minor changes in the shape.

Conclusion: Lateral outfracture of the inferior turbinate produces varied and inconsistent changes in morphology which may affect the shape, size and position of the turbinate.

Who Feels Inferior? A Test of the Status Anxiety Hypothesis of Social Inequalities in Health

The empirical association between income inequality, population health and other social problems is now well established and the research literature suggests that the relationship is not artefactual. Debate is still ongoing as to the cause of this association. Wilkinson, Marmot and colleagues have argued for some time that the relationship stems from the psycho-social effects of status comparisons. Here, income inequality is a marker of a wider status hierarchy that provokes an emotional stress response in individuals that is harmful to health and well-being. We label this the ‘status anxiety hypothesis’. If true, this would imply a structured relationship between income inequality at the societal level, individual income rank and anxiety relating to social status. This paper sets out strong and weak forms of the hypothesis and then presents three predictions concerning the structuring of ‘status anxiety’ at the individual level given different levels of national income inequality and varying individual income. We then test these predictions using data from a cross-national survey of over 34,000 individuals carried out in 2007 in 31 European countries. Respondents from low inequality countries reported less status anxiety than those in higher inequality countries at all points on the income rank curve. This is an important precondition of support for the status anxiety hypothesis and may be seen as providing support for the weaker version of the hypothesis. However, we do not find evidence to support the stronger version of the hypothesis which requires the negative effect of income rank on status anxiety to be exacerbated by increasing income inequality.

Presentation of a plasmablastic lymphoma in a human immunodeficiency virus-positive patient after administration of an inferior alveolar dental block

Human immunodeficiency virus (HIV) is a serious worldwide healthcare problem with implications for all healthcare workers. The reported oral manifestations of the disease are numerous and have been categorised according to the strength of their association with HIV infection. Oral non-Hodgkin's lymphoma is strongly associated with HIV infection, and an increased incidence of such neoplasms is widely reported. This case report details the presentation of a rare subcategory of plasmablastic lymphoma in an HIV-positive patient after administration of an inferior alveolar dental block to facilitate extraction of mandibular teeth. This highly aggressive neoplasm is a large B-cell lymphoma with a predilection for the oral cavity. Unfortunately, the prognosis for such a tumour is poor as detailed in this case.