Moving towards More Diverse and Welcoming Conference Spaces: Data-Driven Perspectives from Biology Education Research Scholars

Academic conferences are integral to the dissemination of novel research findings and discussion of pioneering ideas across all postsecondary disciplines. For some participants, these environments are spaces to develop new collaborations, research projects, and social bonds; however, for others, conferences can be a place of marginalization and outright hostility. To assess how diverse individuals experience conference spaces, we interpreted results from a conference climate survey filled out by 198 of 482 registrants of the Society for the Advancement of Biology Education Research (SABER) West 2021 conference. Analysis of the survey data was conducted by six biology education researchers, who in addition to raising conference participant voices, provide insights, and next steps whose implementation can promote greater participant equity, representation, and engagement in future science, technology, engineering, and math (STEM) education conferences specifically and potentially all academic conference spaces more broadly.

Post-stimulatory activity in primate auditory cortex evoked by sensory stimulation during passive listening

Under certain circumstances, cortical neurons are capable of elevating their firing for long durations in the absence of a stimulus. Such activity has typically been observed and interpreted in the context of performance of a behavioural task. Here we investigated whether post-stimulatory activity is observed in auditory cortex and the medial geniculate body of the thalamus in the absence of any explicit behavioural task. We recorded spiking activity from single units in the auditory cortex (fields A1, R and RT) and auditory thalamus of awake, passively-listening marmosets. We observed post-stimulatory activity that lasted for hundreds of milliseconds following the termination of the acoustic stimulus. Post-stimulatory activity was observed following both adapting, sustained and suppressed response profiles during the stimulus. These response types were observed across all cortical fields tested, but were largely absent from the auditory thalamus. As well as being of shorter duration, thalamic post-stimulatory activity emerged following a longer latency than in cortex, indicating that post-stimulatory activity may be generated within auditory cortex during passive listening. Given that these responses were observed in the absence of an explicit behavioural task, post-stimulatory activity in sensory cortex may play a functional role in processes such as echoic memory and temporal integration that occur during passive listening.

Contrast gain control occurs independently of both parvalbumin-positive interneuron activity and shunting inhibition in auditory cortex

Contrast gain control is the systematic adjustment of neuronal gain in response to the contrast of sensory input. It is widely observed in sensory cortical areas and has been proposed to be a canonical neuronal computation. Here, we investigated whether shunting inhibition from parvalbumin-positive interneurons-a mechanism involved in gain control in visual cortex-also underlies contrast gain control in auditory cortex. First, we performed extracellular recordings in the auditory cortex of anesthetized male mice and optogenetically manipulated the activity of parvalbumin-positive interneurons while varying the contrast of the sensory input. We found that both activation and suppression of parvalbumin interneuron activity altered the overall gain of cortical neurons. However, despite these changes in overall gain, we found that manipulating parvalbumin interneuron activity did not alter the strength of contrast gain control in auditory cortex. Furthermore, parvalbumin-positive interneurons did not show increases in activity in response to high-contrast stimulation, which would be expected if they drive contrast gain control. Finally, we performed in vivo whole-cell recordings in auditory cortical neurons during high- and low-contrast stimulation and found that no increase in membrane conductance was observed during high-contrast stimulation. Taken together, these findings indicate that while parvalbumin-positive interneuron activity modulates the overall gain of auditory cortical responses, other mechanisms are primarily responsible for contrast gain control in this cortical area.NEW & NOTEWORTHY We investigated whether contrast gain control is mediated by shunting inhibition from parvalbumin-positive interneurons in auditory cortex. We performed extracellular and intracellular recordings in mouse auditory cortex while presenting sensory stimuli with varying contrasts and manipulated parvalbumin-positive interneuron activity using optogenetics. We show that while parvalbumin-positive interneuron activity modulates the gain of cortical responses, this activity is not the primary mechanism for contrast gain control in auditory cortex.

Retention following Two-Stage Collaborative Exams Depends on Timing and Student Performance

Multistage collaborative exams are implemented to enhance learning and retention of course material. However, the effects of multistage collaborative exams on retention of course content are varied. These discrepancies may be due to a number of factors. To date, studies examining collaborative exams and content retention have used questions that all, or mostly, require students to select an answer, rather than generate one of their own. However, content retention can improve when students generate their own responses. Thus, we examined the effect of collaborative exams with open-ended questions on retention of course content. Retention was measured at two time periods; one relatively shortly (9 days) following a collaborative exam and another over a longer time period (23 days). Furthermore, we examined whether content retention differed for low-, mid-, or high--performing students. Our results suggest that collaborative exams offer retention benefits at relatively long time periods between pre- and posttests, but not over shorter time periods. Retention varied across students in different performance categories. Our study, the first to use only open-ended questions, showed relatively small effects compared with studies using multiple-choice or fill-in-the-blank format, but still suggest that collaborative exams can aid in content retention.

Contrast gain control in mouse auditory cortex

The neocortex is thought to employ a number of canonical computations, but little is known about whether these computations rely on shared mechanisms across different neural populations. In recent years, the mouse has emerged as a powerful model organism for the dissection of the circuits and mechanisms underlying various aspects of neural processing and therefore provides an important avenue for research into putative canonical computations. One such computation is contrast gain control, the systematic adjustment of neural gain in accordance with the contrast of sensory input, which helps to construct neural representations that are robust to the presence of background stimuli. Here, we characterized contrast gain control in the mouse auditory cortex. We performed laminar extracellular recordings in the auditory cortex of the anesthetized mouse while varying the contrast of the sensory input. We observed that an increase in stimulus contrast resulted in a compensatory reduction in the gain of neural responses, leading to representations in the mouse auditory cortex that are largely contrast invariant. Contrast gain control was present in all cortical layers but was found to be strongest in deep layers, indicating that intracortical mechanisms may contribute to these gain changes. These results lay a foundation for investigations into the mechanisms underlying contrast adaptation in the mouse auditory cortex. NEW & NOTEWORTHY We investigated whether contrast gain control, the systematic reduction in neural gain in response to an increase in sensory contrast, exists in the mouse auditory cortex. We performed extracellular recordings in the mouse auditory cortex while presenting sensory stimuli with varying contrasts and found this form of processing was widespread. This finding provides evidence that contrast gain control may represent a canonical cortical computation and lays a foundation for investigations into the underlying mechanisms.

Best practices in active and student-centered learning in physiology classes

This review article includes our analysis of the literature and our own experiences in using various types of active learning as best practices for evidence-based teaching in physiology. We have evaluated what physiology students should be expected to learn and what are specific challenges to enhancing their learning of physiology principles. We also consider how the instructor should design his or her teaching to improve buy-in from both students and other faculty members. We include a discussion of how the readers can evaluate their teaching approaches for their successes in enhancing student learning of physiology. Thus we have addressed pedagogical improvements specific to student learning of physiology, with additional suggestions from cognitive psychology approaches that can improve physiology teaching and learning.

Hearing in noisy environments: noise invariance and contrast gain control

Contrast gain control has recently been identified as a fundamental property of the auditory system. Electrophysiological recordings in ferrets have shown that neurons continuously adjust their gain (their sensitivity to change in sound level) in response to the contrast of sounds that are heard. At the level of the auditory cortex, these gain changes partly compensate for changes in sound contrast. This means that sounds which are structurally similar, but have different contrasts, have similar neuronal representations in the auditory cortex. As a result, the cortical representation is relatively invariant to stimulus contrast and robust to the presence of noise in the stimulus. In the inferior colliculus (an important subcortical auditory structure), gain changes are less reliably compensatory, suggesting that contrast- and noise-invariant representations are constructed gradually as one ascends the auditory pathway. In addition to noise invariance, contrast gain control provides a variety of computational advantages over static neuronal representations; it makes efficient use of neuronal dynamic range, may contribute to redundancy-reducing, sparse codes for sound and allows for simpler decoding of population responses. The circuits underlying auditory contrast gain control are still under investigation. As in the visual system, these circuits may be modulated by factors other than stimulus contrast, forming a potential neural substrate for mediating the effects of attention as well as interactions between the senses.

Temporal predictability enhances auditory detection

Periodic stimuli are common in natural environments and are ecologically relevant, for example, footsteps and vocalizations. This study reports a detectability enhancement for temporally cued, periodic sequences. Target noise bursts (embedded in background noise) arriving at the time points which followed on from an introductory, periodic "cue" sequence were more easily detected (by ∼1.5 dB SNR) than identical noise bursts which randomly deviated from the cued temporal pattern. Temporal predictability and corresponding neuronal "entrainment" have been widely theorized to underlie important processes in auditory scene analysis and to confer perceptual advantage. This is the first study in the auditory domain to clearly demonstrate a perceptual enhancement of temporally predictable, near-threshold stimuli.

R-Isovaline: a subtype-specific agonist at GABA(B)-receptors?

The R-enantiomer of isovaline, an analgesic amino acid, has a chemical structure similar to glycine and GABA. Although its actions on thalamic neurons are strychnine-resistant and independent of the Cl(-) gradient, R-isovaline increases membrane conductance for K(+). The purpose of this study was to determine if R-isovaline activated metabotropic GABA(B) receptors. We used whole-cell voltage-clamp recordings to characterize the effects of R-isovaline applied by bath perfusion and local ejection from a micropipette to thalamic neurons in 250 μm thick slices of rat brain. The immunocytochemical methods that we employed to visualize GABA(B1) and GABA(B2) receptor subunits showed extensive staining for both subunits in ventrobasal nuclei, which were the recording sites. Bath or local application of R-isovaline caused a slowly developing increase in conductance and outward rectification in 70% (54/77) of neurons, both effects reversing near the K(+) Nernst potential. As with the GABA(B) agonist baclofen, G proteins likely mediated the R-isovaline effects because they were susceptible to blockade by non-hydrolyzable substrates of guanosine triphosphate. The GABA(B) antagonists CGP35348 and CGP52432 prevented the conductance increase induced by R-isovaline, applied by bath or local ejection. The GABA(B) allosteric modulator CGP7930 enhanced the R-isovaline induced increase in conductance. At high doses, antagonists of GABA(A), GABA(C), glycine(A), μ-opioid, and nicotinic receptors did not block R-isovaline responses. The observations establish that R-isovaline increases the conductance of K(+) channels coupled to metabotropic GABA(B) receptors. Remarkably, not all neurons that were responsive to baclofen responded to R-isovaline. The R-isovaline-induced currents outlasted the fast baclofen responses and persisted for a 1-2-h period. Despite some similar actions, R-isovaline and baclofen do not act at identical GABA(B) receptor sites. The binding of R-isovaline and baclofen to the GABA(B) receptor may not induce the same conformational changes in receptor proteins or components of the intracellular signaling pathways.

Effects of the beta-amino acid antagonist TAG on thalamocortical inhibition

Chemical transmission at inhibitory synapses in thalamus may involve receptor activation by beta-amino acids and glycine, as well as GABA. Given their hypothesized roles, we investigated effects of the putative beta-amino acid antagonist 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide (TAG) on synaptic inhibition in dorsal thalamus. We performed whole-cell recordings in 200-250 microm sections and immunocytochemical (ICC) studies in ventrobasal thalamus of rat brain (P12-P14). Stimulation of medial lemniscus evoked inhibitory postsynaptic currents (IPSCs) which were purely glycinergic or GABA(A)ergic, or most commonly mixed glycinergic and GABA(A)ergic responses, based on abolition by strychnine, bicuculline, or combined antagonism. TAG antagonized mixed IPSCs (IC(50) approximately 70 microM) in a manner distinguishable from classical glycine and GABA(A) receptor antagonists. TAG (250 microM) reduced the amplitude of glycinergic components which had a decay time constant of approximately 9 ms or approximately 230 ms by 45-50%, and a GABA(A)ergic component which had a decay time constant of approximately 40 ms by approximately 60%. As in the glycinergic component, TAG reduced the amplitude of infrequently occurring, pure glycinergic IPSCs. Surprisingly, TAG had no effect on pure GABA(A)ergic IPSCs, with a decay time constant of approximately 20 ms that correlated to kinetics of GABA-activated channels. ICC studies showed co-localization of alpha(1/2) glycine and alpha(4) GABA(A) receptors at inhibitory synapses. Activation of alpha(4) receptors by beta-amino acids may contribute to the GABA(A)ergic component of mixed IPSCs. The short and long-duration glycinergic IPSCs had decay time constants that correlated to the burst durations of single channels opened by beta-amino acids and glycine. Overall, the effects of TAG implicate beta-amino acid involvement in GABA(A)ergic and glycinergic transmission.

Detection of sinusoidal amplitude modulated sounds: deficits after bilateral lesions of auditory cortex in the rat

The ability of rats to detect the presence of sinusoidal amplitude modulation (AM) of a broadband noise carrier was determined before and after bilateral ablation of auditory cortex. The rats were trained to withdraw from a drinking spout to avoid a shock when they detected a modulation of the sound. Sensitivity was evaluated by testing the rats at progressively smaller depths of modulation. Psychophysical curves were produced to describe the limits of detection at modulation rates of 10, 100 and 1000Hz. Performance scores were based on the probability of withdrawal from the spout during AM (warning periods) relative to withdrawal during the un-modulated noise (safe periods). A threshold was defined as the depth of modulation that produced a score halfway between perfect avoidance and no avoidance (performance score=0.5). Bilateral auditory cortical lesions resulted in significant elevations in threshold for detection of AM at rates of 100 and 1000Hz. No significant shift was found at a modulation rate of 10Hz. The magnitude of the deficit for AM rates of 100 and 1000Hz was positively correlated with the size of the cortical lesion. Substantial deficits were found only in animals with lesions that included secondary as well as primary auditory cortical areas. The results show that the rat's auditory cortex is important for processing sinusoidal AM and that its contribution is most apparent at high modulation rates. The data suggest that the auditory cortex is a crucial structure for maintaining normal sensitivity to temporal modulation of an auditory stimulus.

Behavioral Limits of Auditory Temporal Resolution in the Rat: Amplitude Modulation and Duration Discrimination

Thresholds for detecting the presence of amplitude modulation in a noise carrier were determined for rats using conditioned avoidance procedures. There was a progressive increase in threshold with modulation rates between 5 Hz and 2 kHz. Further tests were conducted to determine difference thresholds for detecting an increase in modulation rate for standard rates of 10, 50, and 100 Hz. The size of the difference threshold increased progressively as the standard rate increased. In addition, thresholds for detecting an increase in the duration of a noise burst were determined for various standard durations. The difference thresholds were constant for values between 10 and 50 ms but increased progressively, with standard durations between 0.1 and 1.0 s.

A 28 year old woman with ventricular tachycardia and an abnormal chest radiograph

A 28 year old white woman with no medical history presented to the emergency room with symptomatic non-sustained ventricular tachycardia. She was asymptomatic up to a few days before presentation. Her physical examination was essentially normal and hence did not help with the differential diagnosis of the problem. Bronchoscopic transbronchial biopsy led to the final diagnosis of cardiac sarcoidosis.

Regulation of loblolly pine (Pinus taeda L.) arginase in developing seedling tissue during germination and post-germinative growth

After seed germination, hydrolysis of storage proteins provides a nitrogen source for the developing seedling. In conifers the majority of these reserves are located in the living haploid megagametophyte tissue. In the developing loblolly pine (Pinus taeda L.) seedling an influx of free amino acids from the megagametophyte accompanies germination and early seedling growth. The major component of this amino acid pool is arginine, which is transported rapidly and efficiently to the seedling without prior conversion. This arginine accounts for nearly half of the total nitrogen entering the cotyledons and is likely a defining factor in early seedling nitrogen metabolism. In the seedling, the enzyme arginase is responsible for liberating nitrogen, in the form of ornithine and urea, from free arginine supplied by the megagametophyte. In this report we investigate how the seedling uses arginase to cope with the large arginine influx. As part of this work we have cloned an arginase cDNA from a loblolly pine expression library. Analysis of enzyme activity data, accumulation of arginase protein and mRNA abundance indicates that increased arginase activity after seed germination is due to de novo synthesis of the enzyme. Our results suggest that arginase is primarily regulated at the RNA level during loblolly pine seed germination and post-germinative growth.

The role of interleukin-4 in the regulation of mouse primordial germ cell numbers

Interleukin-4 (IL-4), a pleiotropic cytokine, stimulates a dose-dependent increase in the number of mouse primordial germ cells in culture. Results from bromodeoxyuridine incorporation assays suggest that IL-4 acts as a survival factor rather than as a mitogen for primordial germ cells in this system. Studies on the embryonic expression patterns of IL-4 and its receptors, using RT-PCR and ELISA, show that IL-4 and its receptors are present at the correct time and place to influence PGC numbers in vivo.

Electroencephalographic quantitation of opioid effect: comparative pharmacodynamics of fentanyl and sufentanil

The authors compared the pharmacodynamics of sufentanil with those of fentanyl using the electroencephalogram (EEG) as a measure of opioid drug effect. Sixteen patients were given a rapid infusion of sufentanil (18.75 micrograms/min) during EEG recording. To quantitate the opioid-induced slowing of the EEG, the authors analyzed its power spectrum and calculated the spectral edge. An inhibitory sigmoid Emax model of the maximal decrease in spectral edge produced by the opioid related spectral edge values to serum concentrations of sufentanil. The resulting data for the pharmacodynamic parameters of sufentanil were compared with fentanyl parameters that were obtained by reanalysis from an identically conducted, previously published study. The half-time of blood-brain equilibration (T1/2Keo) was not statistically different between sufentanil and fentanyl (6.2 +/- 2.8 vs. 6.6 +/- 1.7 min, mean +/- SD, respectively). The intrinsic potency of sufentanil, as measured by the serum concentration needed to cause half the maximal EEG slowing (IC50), was 12-fold greater (0.68 +/- 0.31 ng/ml) than that of fentanyl (8.1 +/- 2.2 ng/ml). The second part of the study verified the hypothesis that administration of equipotent bolus doses would produce equal onset times. Bolus injections of either 125 micrograms of sufentanil or 1,250 micrograms of fentanyl were given during EEG recording. The time from injection to 50% maximal EEG slowing (T50) was calculated for each patient. The values for T50 for the two groups did not differ. The authors conclude that fentanyl and sufentanil have similar pharmacodynamic profiles, the former being 12 times more potent than the latter.

Marfan syndrome in the parturient

Early recognition of the Marfan Syndrome and knowledge of its potentially lethal complications facilitates successful treatment of these individuals. It is through a joint effort by many specialist physicians such as the obstetrician, cardiologist, and anesthesiologist that these patients can be managed safely through pregnancy, labor, and delivery.

Colloid oncotic pressure as a guide for the anesthesiologist in directing fluid therapy

One useful but underused parameter of fluid replacement is colloid oncotic pressure. Colloid oncotic pressure (COP) is one of the Starling forces that maintain a balance between intravascular and extravascular fluid. Systemic and pulmonary circulations exhibit differences that limit the usefulness of COP manipulation in the treatment of pulmonary edema, especially that associated with hypoxic damage or pulmonary contusion. Systemic transcapillary fluid transport, however, is governed significantly by COP, and serial measurements of COP can serve as useful guides for colloid replacement. In this paper we present instances in which COP determinations were found to be clinically helpful, and discuss colloid replacement during surgery.

A rational approach to anaesthetic premedication

Rational use of premedication for anaesthesia must always be modified and updated to keep pace with the evolving fields of anaesthesiology and surgery, as well as to meet changing patient needs and preferences. It is no longer axiomatic that all patients require, and therefore should receive, premedication. Unfortunately, a variety of traditional reasons have been proposed to justify routine premedication in many institutions. Smoothing induction, decreasing reflexes and arrhythmias, decreasing nausea and vomiting, decreasing pain, decreasing secretions, and producing sedation and amnesia have all been claimed historically as beneficial results of premedication. Modern anaesthetic agents and techniques have come a long way towards eliminating the routine need for premedication. In the preoperative period, the goal of an anxiety-free patient who is physiologically uncompromised requires an individualised approach based on experience and an adequate knowledge of current pharmacology. As our knowledge of potential problems associated with anaesthesia has expanded, we have added other classes of drugs such as the H2-histamine receptor blockers and antacids to our premedicant armamentarium. Outpatient and short-stay patients have further challenged our preoperative goal of an anxiety-free patient by requiring individuals to be 'street ready' within a brief period of time after surgery. Even for in-house elective procedures, not every patient is a candidate for routine premedication. A frank preoperative discussion is all that is necessary to effectively allay anxiety in many persons. In these and other special situations, this article will hopefully guide the reader toward a more rational approach to premedicating patients.

Beyond career choice: the role of learning style analysis in residency training

A recent article in this journal took an important step toward rethinking the utility of behavioural instruments designated as learning style tests (Jewett et al. 1987). The authors of that paper made much of a distinction between the terms 'learning style' and 'learning preference'. However, the results of their study do not seem to substantiate a marked difference between the function of the Rezler Learning Preference Inventory (LPI) and Kolb's Learning Style Inventory (LSI) with which it was contrasted. The most important aspect of their paper was that it rescued the concept of learning style analysis from the arena of career choice prediction at the undergraduate level and applied these ideas to doctors who had already made their specialty selections and were actively engaged in residency training. Clinical instructors in teaching institutions have, for the most part, little or no formal background in educational principles. For these individuals, an easily comprehensible model of resident-instructor psychology can be very useful on a daily basis. This article reviews the authors' experience with the LSI and describes their utilization of Kolb's Experimental Learning Model in the areas of resident counselling and residency curriculum design. The results of two recent studies are also presented in which learning style was examined as a predictor of success in residency, and teacher-resident learning style distributions were shown to exhibit parallel relationships at four different anaesthesiology residency training programmes.

Headache after lumbar puncture: review of the epidural blood patch

The incidence of accidental dural puncture during epidural block is 2.9%; headache follows in as many as 76.5% of these patients. Treatment by injection of autologous blood into the epidural space has gained wide acceptance since its introduction in 1960, though it is contraindicated by blood dyscrasias, anticoagulant therapy, bleeding, and localized infection. The procedure is done by slowly injecting 15 to 20 ml of blood into the same interspace, no sooner than 24 hours after the original puncture. Serious complications are rare.

Testing computer-controlled infusion pumps by simulation

The pharmacokinetic behavior of intravenous anesthetic drugs can be described by two- or three-compartment models. Rapid achievement and maintenance of steady plasma concentrations of these drugs requires a complicated delivery scheme, perhaps best controlled by a computer. The authors developed a method of simulating the performance of a computer-controlled infusion pump from the differential equations describing drug transfer between compartments. They also derived a mathematically simple and flexible approximate solution to these equations using Euler's numerical method. They incorporated this approximate solution into a computer-controlled infusion pump for intravenous drugs. They tested their pump by simulating the administration of fentanyl to a hypothetical patient whose fentanyl pharmacokinetics were described by a three-compartment model. The exact analytical solution served as the standard of comparison. The approximation technique, using a 15-s interval between model updates, had a maximum error of 0.35 ng.ml-1, and rapidly converged on the exact solution. The simulations revealed oscillations in the system. The authors suggest that such simulations be used to evaluate computer-controlled infusion pumps prior to clinical trials of these devices.

Selection of anesthesiology residents

The large numbers of medical graduates seeking residency training in anesthesiology have created a logistical problem for many programs. This difficulty and the recurrent phenomenon of the misplaced physician have prompted a search for better selection criteria and more efficient evaluation systems. The literature does not provide a concise description of the ideal resident candidate, but it does contain several approaches taken by a few individual teaching centers to improve applicant review procedures. Computer-assisted resident candidate selection (CARCS) is a three-phase system of preinterview screening, interview evaluation, and final ranking. Based on faculty criteria, the entire process uses data management technology that provides automatic calculation of selection parameters, sorting on any data field or combination thereof, and maintenance of a concise information profile for each candidate. CARCS allows equitable consideration of all who apply, with significant cost savings to both program and applicants. This paper reviews traditional methods of selecting anesthesiology residents, describes the CARCS system, and previews the future of resident candidate selection.

Drug interactions in anesthesia

The threat of adverse drug interactions increases daily as more and more drugs become available. All physicians should be familiar with the problems of drug interactions and their management. Careful preoperative evaluation and screening combined with limited prescribing can help to limit the magnitude of this problem.

A stereotaxic system for independent coordinated positioning of two or three microelectrodes

This paper describes a straightforward, easily built and relatively inexpensive stereotaxic system that permits independent coordinated positioning of 2 or 3 microelectrodes. This system is ideally suited for situations where the ability to routinely place one electrode at a precise position relative to another is important. Resolution of relative position and interelectrode distance is +/- 50 micrometers. This system should prove useful for the study of local interactions in such neural aggregates as nuclei, motoneuron pools and within and between cortical columns.