Jane Mellanby

The 'gender gap' in final examination results at Oxford University.

A lower proportion of women than men obtain first class degrees at British universities (the so-called gender gap). At Oxford University, this difference is not seen in all degree subjects but is found both in some Arts and in some Science subjects. We have used a questionnaire administered under supervision to undergraduates 2 to 3 months before their final examination to assess factors which might be expected to affect examination performance. These included measures of verbal and non-verbal reasoning (Alice Heim AH6 test), self-esteem, motivation, responses to stresses of examinations and of personal relationships, happiness, risk-taking and working patterns. We have also obtained a detailed breakdown of the marks the students were given in the examination. Women scored higher on negative emotions while men scored higher on self-esteem, their perception of their own academic efficacy and on risk-taking strategies, but none of these factors predicted outcome. Verbal reasoning ability did predict outcome but there was no gender difference. Hence, it is concluded that the gender gap is not due to any of these individual differences and is more likely to be related to the nature of the academic assessment system.

The Effect of Cerebroside and Other Lipids on the Fixation of Tetanus Toxin by Gangliosides

SUMMARY: Water-insoluble complexes of ganglioside with cerebroside fixed tetanus toxin at low concentrations (a few LD 50/ml.) of toxin. A complex containing 25% ganglioside with cerebroside was 50 times better at fixing toxin than complexes containing either 2% or 50% ganglioside. A complex containing 25% of a mixture of the gangliosides Giii and Giv was 12 times better at fixing toxin than a similar complex with gangliosides Gi and GII. Complexes of ganglioside with sphingomyelin and lecithin fixed toxin to a slight extent, while complexes with tripalmitin and cholesterol did not fix toxin. The complex of cerebroside and ganglioside, containing 25% ganglioside, did not fix strychnine, serotonin, botulinum toxin or plasma albumin.

Limbic Epilepsy Induced by Tetanus Toxin: A Longitudinal Electroencephalographic Study

Summary: An epileptiform syndrome was induced in rats by injection of tetanus toxin (–10 mouse LD50) unilaterally into the hippocampus. Continuous EEG records were obtained from implanted hippocampal electrodes for periods of 4–7 weeks in 14 rats. In a pilot study of two of these rats, three more recording electrodes were placed in other brain areas. Six of the rats (including the latter two) were simultaneously filmed using time‐lapse videorecording, and the relationships between EEG events and overt motor fits were assessed using a split‐screen video monitoring system. Characteristic peaks and troughs in the numbers of overt fits occurring each day were noted in all the rats that were filmed, and less marked peaks occurred in the numbers of hippocampal seizure discharges. At the start of the syndrome, seizure discharges occurred without accompanying fits; then overt fits occurred with some of the discharges; later the animals stopped having fits but seizure discharges continued to occur alone for several weeks. Fits only occurred with longer seizure discharges (more than –30 s), but not all longer seizures were associated with fits. Whether or not a hippocampal seizure discharge leads to a motor fit appears to depend not on the nature of the electrical activity in the hippocampus but probably on the properties of areas, such as the cingulate gyrus, to which the seizure activity may spread. Large epileptiform spikes occurred throughout the syndrome, and their frequency was often increased for some minutes after a seizure discharge. While there was an overall correlation between the number of fits and the number of seizure discharges occurring during the entire syndrome, within relatively brief periods this relation was not consistent. The occurrence of motor fits was often associated with a decrease in seizure discharge frequency. In the four rats with bilateral electrodes, some independent EEG activity was observed in the uninjected hippocampus.

Attitudes to e-learning, learning style and achievement in learning neuroanatomy by medical students

Background: Two main learning approaches adopted by students have been identified by research: deep (seeking for meaning motivated by interest in the subject matter) and surface (rote-learning motivated by fear of failure). There is evidence that learning approach is influenced by learning environment (e.g. Trigwell et al. ). Online courses pose the challenge of designing software that will encourage the more desirable approach to learning. Aims: The aims were to evaluate how successful an online course is at encouraging deep approach to learning, which factors might influence the approach adopted towards it, and whether the approach adopted is related to academic performance. Method: Using 205 second-year pre-clinical medical students, we compared their approach to learning, as measured by Biggs et al. () 2F-SPQ-R, for a computer-aided learning (CAL) course in Neuroanatomy with that for their studies in general. We then examined student attitudes towards the CAL course and the ratings of the course Web pages in terms of the learning approach they encourage (done by 18 independent raters). Results: The students reported using significantly less deep approach to learning for the CAL course. However, their approach for the course was not related to results on a neuroanatomy assessment based on it. Enjoyment of the course, assessment of the amount of information in it as appropriate, and ease of understanding the course were all associated with a deeper approach. The only agreement between the raters of the CAL course was for some pages that included patient case studies, which were unanimously given a very high deep rating. Assessment marks for questions referring to these pages were higher than for the rest of the assessment. Conclusions: The study suggests that maximizing the use of clinical relevance should increase the interest and enjoyableness of the course and thereby aid deep learning and retention of information.

The effects of compounds related to γ-aminobutyrate and benzodiazepine receptors on behavioural responses to anxiogenic stimuli in the rat: Punished barpressing

Rats were trained to press a bar for sucrose reward on a random-interval (RI) schedule and footshock punishment was then introduced for 3-min intrusion periods (signalled by a tone) on an independent RI schedule. Shock intensity was individually adjusted to produce stable intermediate levels of response suppression during the tone for each animal. Groups of animals were then allocated to a number of separate experiments in which they were systemically injected with anxiolytics (chlordiazepoxide HCl or sodium amylobarbitone), GABA antagonists (picrotoxin or bicuculline), the GABAA agonist muscimol, the GABAB agonist baclofen, an antagonist (RO 15-1788) at the benzodiazepine receptor and, an inverse agonist (FG 7142) at this receptor. The results showed that the alleviation of punishment-induced suppression of barpressing produced by chlordiazepoxide was blocked or partially blocked by RO 15-1788, picrotoxin and bicuculline but not by FG 7142; that picrotoxin (but not FG 7142) increased the suppression of responding by punishment; that neither muscimol nor baclofen affected responding on their own, but their combination weakly but reliably released punished responding from suppression; and that the anti-punishment effect of amylobarbitone was unaffected by either picrotoxin or bicuculline, though the barbiturate reversed the punishment-enhancing effect of picrotoxin. These results are discussed in the light of the hypothesis that anxiolytic behavioural effects are due to increased GABAergic inhibition.

Septal driving of hippocampal theta rhythm: A role for γ-aminobutyrate in the effects of minor tranquillizers?

Abstract In male rats, when the hippocampal theta rhythm is artificially driven by stimulation in the septum at frequencies between 5 and 10 Hz, the function relating frequency to the threshold current required to drive the theta rhythm at that frequency has a minimum at 7.7 Hz. The minor tranquillizers chlordiazepoxide and amobarbital sodium abolish this minimum and it has been proposed that this action correlates with their anxiolytic effects. The flattening of the curve produced by chlordiazepoxide (5 mg/kg) was antagonized by picrotoxin (0.75 mg/kg) but not by bicuculline (2.5 mg/kg). The flattening produced by amobarbital sodium (15 mg/kg) was not antagonized by either picrotoxin (2 mg/kg) or bicuculline (2.5 mg/kg). Muscimol, a γ-aminobutyrate agonist, acted like a minor tranquillizer on the theta-driving curve. The dose response-curve for this effect was an inverted-U and the muscimol still produced significant flattening at a dose of less than 0.001 mg/kg. The effect of muscimol was antagonized by bicuculline (2.5 mg/kg) but not by picrotoxin (2 mg/kg). The results are discussed in relation to the hypothesis that γ-aminobutyrate may be involved in anxiety.

In Vitro Effect of Tetanus Toxin on GAB A Release from Rat Hippocampal Slices

Abstract Ca2+‐dependent K+‐stimulated γ‐aminobutyric acid release from rat hippocampal slices was reduced about 30% by pre‐incubation of the slices with 104 mouse LD50/ml tetanus toxin for 3 h at 37°C.

A Note on the Specific Fixation, Specific Deactivation and Non-Specific Inactivation of Bacterial Toxins by Gangliosides

SummaryThe fixation of tetanus toxin and the deactivation of cholera toxin by gangliosides are toxin-specific and ganglioside-specific, and not prevented by protective colloid, whereas the inactivation of a number of toxins by gangliosides which is prevented by protective colloid is a non-specific phenomenon.

Ganglioside as a prophylactic agent in experimental tetanus in mice.

SUMMARY: The symptoms of tetanus in mice, resulting from intramuscular injection of either purified tetanus toxin or vegetative bacilli of Clostridium tetani, can be partially prevented if the mice are injected at the same time, or a few hours before or afterwards, with a preparation of mixed gangliosides or with a suspension of ganglioside/cerebroside complex. Injection at the same site as the toxin injection is most effective, although intravenous injection of ganglioside (but not of the complex) also has some action; 0.5 mg. of ganglioside when complexed with 1.5 mg. cerebroside is as effective in protection as 5 mg. ganglioside alone. Protection by complexes containing different proportions of ganglioside reflects their ability to fix tetanus toxin in vitro. It is tentatively suggested that injection of ganglioside/cerebroside complex at a site of injury might be of prophylactic value in human tetanus.

The effects of compounds related to γ-aminobutyrate and benzodiazepine receptors on behavioural responses to anxiogenic stimuli in the rat: Extinction and successive discrimination

In a first set of experiments rats were trained to run in a straight alley for food reward on a continuous reinforcement schedule and the running response was then extinguished. On the last 2 days of training and daily throughout extinction different groups of animals were injected IP with saline, 5 mg/kg chlordiazepoxide, 0.75 mg/kg picrotoxin, chlordiazepoxide + picrotoxin, chlordiazepoxide +1.5 mg/kg bicuculline, 0.00125 or 0.25 mg/kg muscimol, 1 mg/kg baclofen, chlordiazepoxide + baclofen, or 0.00125 mg/kg muscimol + baclofen. Chlordiazepoxide increased resistance to extinction, a well-known anxiolytic effect. This effect was blocked by both picrotoxin and bicuculline. Picrotoxin on its own reduced resistance to extinction (an anxiogenic-like effect). Whether given alone or in combination with other drugs, muscimol and baclofen had no effect.In a second set of experiments rats were trained in a successive operant discrimination (signalled by a flashing or steady light) between components in which sucrose reward was available on a variable-interval schedule for barpressing and components in which no reward was given. Chlordiazepoxide at 10 mg/kg increased responding in both rewarded and nonrewarded components, but more in the latter than could be accounted for by change in the former. This effect is as expected with an anxiolytic drug. It was not altered by administration of bicuculline at 1.5 or 1.75 mg/kg; at 2 mg/kg bicuculline acted synergistically with chlordiazepoxide. Picrotoxin (1 and 1.5 mg/kg) also acted synergistically with chloridazepoxide, enhancing the latters rate-increasing effects, but only during rewarded components. Neither muscimol (0.00125 and 0.25 mg/kg) nor baclofen (0.01 mg/kg) affected response rates, whether given alone or in combination. However, baclofen in a dose of 1 mg/kg, provided it was given to rats also injected with muscimol (0.00125 or 0.25 mg/kg) at other times, significantly reduced responding during nonrewarded components (an apparently anxiogenic effect).The results of the two sets of experiments are discussed in relation to the hypothesis that anxiolytic drugs affect behaviour by increasing GABAergic inhibition.