A neural correlate of oculomotor sequences in supplementary eye field

Complex learned motor sequences can be composed of a combination of a small number of elementary actions. To investigate how the brain represents such sequences, we devised an oculomotor sequence task in which the monkey had to choose the target solely by the sequential context, not by the current stimulus combination. We found that many neurons in the supplementary eye field (SEF) became active with a specific target direction (D neuron) or a specific target/distractor combination (C neuron). Furthermore, such activity was often selective for one among several sequences that included the combination (S neuron). These results suggest that the SEF contributes to the generation of saccades in many learned sequences.     

To Bet, or Not to Bet: That Is the Question of SEF Spikes

The ability of animals to monitor their own cognitive processes is called metacognition. In this issue of Neuron, Middlebrooks and Sommer (2012) show that single-unit activity of SEF neurons exhibit?a metacognitive signal while monkeys perform a postdecision wagering task.     

Covariations between pupil diameter and supplementary eye field activity suggest a role in cognitive effort implementation

In both human and nonhuman primates (NHP), the medial prefrontal region, defined as the supplementary eye field (SEF), can indirectly influence behavior selection through modulation of the primary selection process in the oculomotor structures. To perform this oculomotor control, SEF integrates multiple cognitive signals such as attention, memory, reward, and error. As changes in pupil responses can assess these cognitive efforts, a better understanding of the precise dynamics by which pupil diameter and medial prefrontal cortex activity interact requires thorough investigations before, during, and after changes in pupil diameter. We tested whether SEF activity is related to pupil dynamics during a mixed pro/antisaccade oculomotor task in 2 macaque monkeys. We used functional ultrasound (fUS) imaging to examine temporal changes in brain activity at the 0.1-s time scale and 0.1-mm spatial resolution concerning behavioral performance and pupil dynamics. By combining the pupil signals and real-time imaging of NHP during cognitive tasks, we were able to infer localized cerebral blood volume (CBV) responses within a restricted part of the dorsomedial prefrontal cortex, referred to as the SEF, an area in which antisaccade preparation activity is also recorded. Inversely, SEF neurovascular activity measured by fUS imaging was found to be a robust predictor of specific variations in pupil diameter over short and long-time scales. Furthermore, we directly manipulated pupil diameter and CBV in the SEF using reward modulations. These results bring a novel understanding of the physiological links between pupil and SEF, but it also raises questions about the role of anterior cingulate cortex (ACC), as CBV variations in the ACC seems to be negligible compared to CBV variations in the SEF.

Ultrafast functional imaging reveals short- and long-term covariations between pupil diameter and activity in the Supplementary Eye Field (SEF) of awake behaving non-human primates, yielding a novel understanding of the physiological links between the pupil and SEF.     

Tissue-specific and temporal regulation of a β-conglycinin gene: roles of the RY repeat and other cis-acting elements

Upstream regulatory sequences (URS) of the gene that encodes the subunit of -conglycinin, the 7S soybean seed storage protein, includes two RY repeat elements. The role of RY elements and sequences that bind soybean embryo factors 3 and 4 (SEF3 and SEF4; Allen et al., Plant Cell 1 (1989) 623–631) in regulating expression of the promoter was studied following site directed mutagenesis. Specific mutations introduced into these sequences abolished the in vitro binding activities of SEF3 and SEF4. The biological activities resulting from the mutations were determined in transgenic plants using two chimeric promoters comprising sequences from the CaMV 35S promoter and the subunit promoter. The uidA reporter gene was used to assess the levels of gene expression in transgenic plants. The mutations in the RY element and SEF3 and SEF4 binding sites had little effect on expression of the promoter. By contrast, mutations in the RY element had significant effect on gene expression when the URS from the promoter was ligated upstream of the core 35S promoter. Mutations in the RY element abolished the seed specific enhancing activity of the URS and caused expression of the chimeric promoter in leaves. These results indicate that the RY element plays a key role in seed-specific gene regulation in coordination with other cis-acting elements.     

A simple purification method for enterotoxin F produced by Staphylococcus aureus and some properties of the toxin

Staphyloccoccus aureus enterotoxin F (SEF), which is associated with S. aureus strains isolated from toxic-shock-syndrome patients, was purified by successive chromatography on CM sephadex C-25 and gelfiltration on sephadex G-75. When tested by disc-polyacrylamide gel-electrophoresis the toxin migrated as a homogeneous protein. In SDS-polyacrylamide gel-electrophoresis three protein bands were observed. The main component had a mol wt of 23000 and the two minor components had a mol wt<13 000. By iso-electric focussing a main protein band with an iso-electric point of 7.2 was obtained. The LD₅₀ for rabbits (3–3.5 kg) by subcutaneous and intravenous application of SEF was 6 g and 180 g, respectively. Antibodies to SEF prepared in a sheep did not react with other staphylococcal enterotoxins (A to E).     

Thin, aggregative fimbriae mediate binding of Salmonella enteritidis to fibronectin.

The binding of human fibronectin and Congo red by an autoaggregative Salmonella enteritidis strain was found to be dependent on its ability to produce thin, aggregative fimbriae, named SEF 17 (for Salmonella enteritidis fimbriae with an apparent fimbrin molecular mass of 17 kDa). Two other fimbrial types produced by S. enteritidis, SEF 14 and SEF 21, were not responsible for the aggregative phenotype or for fibronectin binding. SEF 17-negative TnphoA mutants which retained the ability to produce SEF 14 and SEF 21 were unable to bind human fibronectin or Congo red and lost the ability to autoaggregate. Only purified SEF 17 but not purified SEF 14 or SEF 21 bound fibronectin in a solid-phase binding assay. Furthermore, only SEF 17 was able to inhibit fibronectin binding to S. enteritidis whole cells in a direct competition enzyme-linked immunosorbent assay. These results indicate that SEF 17 are the fimbriae responsible for binding fibronectin by this enteropathogen.     

Neuronal correlates of metacognition in primate frontal cortex

Humans are metacognitive: they monitor and control their cognition. Our hypothesis was that neuronal correlates of metacognition reside in the same brain areas responsible for cognition, including frontal cortex. Recent work demonstrated that nonhuman primates are capable of metacognition, so we recorded from single neurons in the frontal eye field, dorsolateral prefrontal cortex, and supplementary eye field of monkeys (Macaca mulatta) that performed a metacognitive visual-oculomotor task. The animals made a decision and reported it with a saccade, but received no immediate reward or feedback. Instead, they had to monitor their decision and bet whether it was correct. Activity was correlated with decisions and bets in all three brain areas, but putative metacognitive activity that linked decisions to appropriate bets occurred exclusively in the SEF. Our results offer a survey of neuronal correlates of metacognition and implicate the SEF in linking cognitive functions over short periods of time.     

Secretory end-feet, extracerebral cells, and cerebral sense organs in certain limicole oligochaete annelids.

Secretory end-feet (or SEF) systems are present in Limnodrilus and Stylodrilus but are less highly organized than those of polychaetes. SEF contain secretory vesicles and abundant mitochondria. Typical neurosecretory terminals are not found within the brain although "neurosecretory" perikarya are present in all four species studied. In Limnodrilus, Stylodrilus and Enchytraeus extracerebral cells, of probable neurosecretory function, are invested by the pericapsular epithelium. Characteristically such cells bear several cilia. In these species and in Stylaria a pair of sensory cell groups is located anteriorly within the brain. These cells are ciliated but lack associated supporting cells.     

The Human Frontal Oculomotor Cortical Areas Contribute Asymmetrically to Motor Planning in a Gap Saccade Task

Background

Saccadic eye movements are used to rapidly align the fovea with the image of objects of interest in peripheral vision. We have recently shown that in children there is a high preponderance of quick latency but poorly planned saccades that consistently fall short of the target goal. The characteristics of these multiple saccades are consistent with a lack of proper inhibitory control of cortical oculomotor areas on the brainstem saccade generation circuitry.

Methodology/Principal Findings

In the present paper, we directly tested this assumption by using single pulse transcranial magnetic stimulation (TMS) to transiently disrupt neuronal activity in the frontal eye fields (FEF) and supplementary eye fields (SEF) in adults performing a gap saccade task. The results showed that the incidence of multiple saccades was increased for ispiversive but not contraversive directions for the right and left FEF, the left SEF, but not for the right SEF. Moreover, this disruption was most substantial during the ∼50 ms period around the appearance of the peripheral target. A control condition in which the dorsal motor cortex was stimulated demonstrated that this was not due to any non-specific effects of the TMS influencing the spatial distribution of attention.

Conclusions/Significance

Taken together, the results are consistent with a direction-dependent role of the FEF and left SEF in delaying the release of saccadic eye movements until they have been fully planned.     

Biological effects of static electric field: Plasma/serum proteome analysis of rats

The external static electric field (SEF) of man-made origin brings to the substantially increased SEF background in a human environment the biological activity of which is a moot question. The paper reports on rats blood plasma/serum proteome modifications by means of 1D polyacrilamide gel electrophoresis and clotting process alterations after the short- and long-term SEF exposures of 200 kV/m. The results indicate decrease of fast α1 and α2 globular proteins in plasma coinciding with clotting acceleration after the short-term SEF, and attenuation of clotting-dependent proteome modifications reflected with incomplete coagulation after the long-term SEF exposure. Increased lysozyme activity in serum unlike plasma was observed after both SEF exposures. Applied model of the high-voltage SEF environment indicates dependence of biological systems functioning on the external SEF.     

Pathogenic role of SEF14, SEF17, and SEF21 fimbriae in Salmonella enterica serovar enteritidis infection of chickens

Very little is known about the contribution of surface appendages of Salmonella enterica serovar Enteritidis to pathogenesis in chickens. This study was designed to clarify the role of SEF14, SEF17, and SEF21 fimbriae in serovar Enteritidis pathogenesis. Stable, single, defined sefA (SEF14), agfA (SEF17), and fimA (SEF21) insertionally inactivated fimbrial gene mutants of serovar Enteritidis were constructed. All mutant strains invaded Caco-2 and HT-29 enterocytes at levels similar to that of the wild type. Both mutant and wild-type strains were ingested equally well by chicken macrophage cell lines HD11 and MQ-NCSU. There were no significant differences in the abilities of these strains to colonize chicken ceca. The SEF14(-) strain was isolated in lower numbers from the livers of infected chickens and was cleared from the spleens faster than other strains. No significant differences in fecal shedding of these strains were observed.     

Application of AAO Matrix in Aligned Gold Nanorod Array Substrates for Surface-Enhanced Fluorescence and Raman Scattering

In this paper, we probed surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) from probe molecule Rhodamine 6G (R6G) on self-standing Au nanorod array substrates made using a combination of anodization and potentiostatic electrodeposition. The initial substrates were embedded within a porous alumina template (AAO). By controlling the thickness of the AAO matrix, SEF and SERS were observed exhibiting an inverse relationship. SERS and SEF showed a non-linear response to the removal of AAO matrix due to an inhomogeneous plasmon activity across the nanorod which was supported by FDTD calculations. We showed that by optimizing the level of AAO thickness, we could obtain either maximized SERS, SEF or simultaneously observe both SERS and SEF together.     

Pathogenic Role of SEF14, SEF17, and SEF21 Fimbriae in Salmonella enterica Serovar Enteritidis Infection of Chickens

Very little is known about the contribution of surface appendages of Salmonella enterica serovar Enteritidis to pathogenesis in chickens. This study was designed to clarify the role of SEF14, SEF17, and SEF21 fimbriae in serovar Enteritidis pathogenesis. Stable, single, defined sefA (SEF14), agfA (SEF17), and fimA (SEF21) insertionally inactivated fimbrial gene mutants of serovar Enteritidis were constructed. All mutant strains invaded Caco-2 and HT-29 enterocytes at levels similar to that of the wild type. Both mutant and wild-type strains were ingested equally well by chicken macrophage cell lines HD11 and MQ-NCSU. There were no significant differences in the abilities of these strains to colonize chicken ceca. The SEF14⁻ strain was isolated in lower numbers from the livers of infected chickens and was cleared from the spleens faster than other strains. No significant differences in fecal shedding of these strains were observed.     

Expression of SEF17 fimbriae by Salmonella enteritidis

M. DIBB-FULLER, E. ALLEN-VERCOE, M. J. WOODWARD AND C. J. THORNS. 1997. Specific immunological reagents were used to investigate the expression of SEF17 fimbriae by cultured strains of Salmonella enteritidis . Most strains of Salm. enteritidis tested expressed SEF17 when cultured at temperatures of 18–30°C. However, two wild-type strains produced SEF17 when also grown at 37 °C and 42 °C. Colonization factor antigen agar was the optimum medium for SEF17 expression, whereas Drigalski and Sensitest agars poorly supported SEF17 production. Very fine fimbriae produced by a strain of Salm. typhimurium were specifically and strongly labelled by SEF17 monoclonal and polyclonal antibodies, indicating considerable antigenic conservation between the two. Curli fimbriae from Escherichia coli were similarly labelled. The production of these fimbriae corellated with the binding of fibronectin by the organism. Congo red binding by cultured bacteria was not a reliable criterion for the expression of SEF17 fimbriae.     

Type 1 fimbriae of Salmonella enteritidis.

Salmonella enteritidis was previously shown to produce fimbriae composed of 14,000-molecular-weight (Mr) fimbrin monomers (J. Feutrier, W. W. Kay, and T. J. Trust, J. Bacteriol. 168:221-227, 1986). Another distinct fimbrial structure, comprising 21,000-Mr fimbrin monomers, has now been identified. These fimbriae are simply designated as SEF 14 and SEF 21, respectively (for S. enteritidis fimbriae and the Mr [in thousands] of the fimbrin monomer). A simple method for the purification of both structures was developed by using the different biochemical properties of these fimbriae. SEF 21 remained intact after being boiled in sodium dodecyl sulfate but readily dissociated into subunits of 21,000 Mr at pH 2.2. The overall amino acid composition and the N-terminal amino acid sequence of the SEF 21 fimbrin were distinct from those of SEF 14 but were virtually identical to the predicted sequence for type 1 fimbrin of Salmonella typhimurium. Immunoelectron microscopy of S. enteritidis clearly revealed fimbrial structures that reacted with immune serum specific to the 21,000-Mr fimbrin. Immune sera raised against this subunit were cross-reactive with type 1 fimbrins found in whole-cell lysates of S. typhimurium, Salmonella illinois, and Salmonella cubana. However, there was no cross-reaction with Escherichia coli type 1 fimbriae or with other fimbrins produced by S. enteritidis. Under certain growth conditions, S. enteritidis produced both SEF 14 and SEF 21. However, when S. enteritidis was grown at 30 degrees C or lower, only the 21,000-Mr SEF 21 fimbrin could be detected. There was a direct correlation between mannose-sensitive hemagglutination and the presence of SEF 21.     

Volition and conflict in human medial frontal cortex

Controversy surrounds the role of human medial frontal cortex in controlling actions. Although damage to this area leads to severe difficulties in spontaneously initiating actions, the precise mechanisms underlying such "volitional" deficits remain to be established. Previous studies have implicated the medial frontal cortex in conflict monitoring and the control of voluntary action, suggesting that these key processes are functionally related or share neural substrates. Here, we combine a novel behavioral paradigm with functional imaging of the oculomotor system to reveal, for the first time, a functional subdivision of the pre-supplementary motor area (pre-SMA) into anatomically distinct areas that respond exclusively to either volition or conflict. We also demonstrate that activity in the supplementary eye field (SEF) distinguishes between success and failure in changing voluntary action plans during conflict, suggesting a role for the SEF in implementing the resolution of conflicting actions. We propose a functional architecture of human medial frontal cortex that incorporates the generation of action plans and the resolution of conflict.