Discrimination of residents during neurosurgical training in Mexico: Results of a survey prior to SARS-CoV-2.

BACKGROUND: Recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic represents an important negative impact on global training of neurosurgery residents. Even before the pandemic, discrimination is a challenge that neurosurgical residents have consistently faced. In the present study, we evaluated discriminatory conditions experienced by residents during their neurosurgical training in Mexico before the SARS-CoV-2 pandemic. METHODS: An electronic survey of 18 questions was sent among residents registered in the Mexican Society of Neurological Surgery (MSNS), between October 2019 and July 2020. Statistical analysis was made in IBM SPSS Statistics 25. The survey focused on demographic characteristics, discrimination, personal satisfaction, and expectations of residents. RESULTS: A response rate of 50% (132 of 264 residents' members of MSNS) was obtained and considered for analysis. Median age was 30.06 ± 2.48 years, 5.3% (n = 7) were female and 16.7% (n = 22) were foreigners undergoing neurosurgical training in Mexico. Approximately 27% of respondents suffered any form of discrimination, mainly by place of origin (9.1%), by gender (8.3%) or by physical appearance (6.1%). About 42.9% (n = 3) of female residents were discriminated by gender versus 6.4% (n = 8) of male residents (P = 0.001); while foreign residents mentioned having suffered 10 times more an event of discrimination by place of origin compared to native Mexican residents (36.4% vs. 3.6%, P < 0.001). CONCLUSION: This manuscript represents the first approximation to determine the impact of discrimination suffered by residents undergoing neurosurgical training in Mexico before the SARS-CoV-2 pandemic.

99mTc-UBI 29-41 bone SPECT/CT scan in craniofacial Actinomyces israelii: Misdiagnosis of cranial bone tumor - A case report.

BACKGROUND: Actinomycosis is a rare infection, frequently misdiagnosed as a neoplasia. This chronic and granulomatous disease is caused by Actinomyces israelii species. Cervicofacial actinomycosis occurs in 60% of cases and the diagnosis is commonly made by histopathology study. CASE DESCRIPTION: We report a case of fronto-orbital osteomyelitis initially misdiagnosed as a cranial bone meningioma, but later proved to be a case of actinomycosis. 99mTechnetium (99mTc) three-phase bone single-photon emission computed tomography/computed tomography (SPECT/CT) and 99mTc-ubiquicidin (UBI) 29-41 bone SPECT/CT scans were performed to corroborate the control of the infection. CONCLUSION: Craniofacial actinomycosis is the most common presentation of actinomycosis. However, it continues to be a rare and difficult disease to diagnose and is often confused with a neoplastic process. The 99mTc-UBI 29-41 bone SPECT/CT scan could be an auxiliary noninvasive diagnostic alternative and a follow-up method for these patients.

Working memory representation of empty sets in the primate parietal and prefrontal cortices.

For the brain, representing empty sets as a precursor to zero is a challenge because it requires the active coding of a quantitative category that, by definition, contains no items. Recent neurophysiological recordings show that empty sets are distinctively encoded by neurons in the primate ventral intraparietal area (VIP) and the prefrontal cortex (PFC). However, how empty sets are represented in working memory is unknown. We simultaneously recorded from VIP and PFC while rhesus monkeys performed a delayed numerosity matching task that required the maintenance of numerosities in memory for a brief period. Countable numerosities (1-4) and empty sets ('numerosity 0') were included as stimuli. Single neurons in PFC, and to a lesser extent neurons in VIP, actively encoded empty sets during the delay period. In both cortical areas, empty sets were progressively differentiated from countable numerosities with time during the ongoing trial. Moreover, the tuning of neuron populations in VIP and PFC shifted dynamically towards empty sets so that they became increasingly overrepresented in working memory. Compared to VIP, the prefrontal representation of empty sets was more stable in time and more independent of low level visual features. Moreover, PFC activity correlated better with behavioral performance in empty set trials. These findings suggest that the representation of null quantity in working memory relies more on prefrontal and less on parietal processing. Overall, our results show that empty sets are dynamically and distinctly represented in working memory.

Memory-guided microsaccades.

Despite strong evidence to the contrary in the literature, microsaccades are overwhelmingly described as involuntary eye movements. Here we show in both human subjects and monkeys that individual microsaccades of any direction can easily be triggered: (1) on demand, based on an arbitrary instruction, (2) without any special training, (3) without visual guidance by a stimulus, and (4) in a spatially and temporally accurate manner. Subjects voluntarily generated instructed "memory-guided" microsaccades readily, and similarly to how they made normal visually-guided ones. In two monkeys, we also observed midbrain superior colliculus neurons that exhibit movement-related activity bursts exclusively for memory-guided microsaccades, but not for similarly-sized visually-guided movements. Our results demonstrate behavioral and neural evidence for voluntary control over individual microsaccades, supporting recently discovered functional contributions of individual microsaccade generation to visual performance alterations and covert visual selection, as well as observations that microsaccades optimize eye position during high acuity visually-guided behavior.

Neuronal Representation of Numerosity Zero in the Primate Parieto-Frontal Number Network.

Neurons in the primate parieto-frontal network represent the number of visual items in a collection, but it is unknown whether this system encodes empty sets as conveying null quantity. We recorded from the ventral intraparietal area (VIP) and the prefrontal cortex (PFC) of monkeys performing a matching task including empty sets and countable numerosities as stimuli. VIP neurons encoded empty sets predominantly as a distinct category from numerosities. In contrast, PFC neurons represented empty sets more similarly to numerosity one than to larger numerosities, exhibiting numerical distance and size effects. Moreover, prefrontal neurons represented empty sets abstractly and irrespective of stimulus variations. Compared to VIP, the activity of numerosity neurons in PFC correlated better with the behavioral outcome of empty-set trials. Our results suggest a hierarchy in the processing from VIP to PFC, along which empty sets are steadily detached from visual properties and gradually positioned in a numerical continuum. These findings elucidate how the brain transforms the absence of countable items, nothing, into an abstract quantitative category, zero.