W. J. Hendelman

Reciprocal Peer Teaching by Medical Students in the Gross Anatomy Laboratory.

The use of reciprocal peer teaching (RPT) was evaluated by 66 first-year medical students participating in gross anatomy laboratory sessions at the University of Ottawa Faculty of Health Sciences. In RPT each student in turn served as a teacher of his peers. The students compared RPT with staff teaching, and almost all reported that they acquired as much knowledge of topics taught by their peers and greater knowledge of topics that they taught personally than they acquired from staff teaching. In addition, most students reported improved study habits, better attitudes toward anatomy, and more independent study. A majority of the students felt they would be better able to communicate with patients and felt more like students of medicine than before participating in RPT. The authors concluded that the active involvement of students in teaching will help prepare students to be continual and independent self-learners throughout their professional careers.

Wanted: role models - medical students’ perceptions of professionalism

BackgroundTransformation of medical students to become medical professionals is a core competency required for physicians in the 21st century. Role modeling was traditionally the key method of transmitting this skill. Medical schools are developing medical curricula which are explicit in ensuring students develop the professional competency and understand the values and attributes of this role. The purpose of this study was to determine student perception of professionalism at the University of Ottawa and gain insights for improvement in promotion of professionalism in undergraduate medical education.MethodsSurvey on student perception of professionalism in general, the curriculum and learning environment at the University of Ottawa, and the perception of student behaviors, was developed by faculty and students and sent electronically to all University of Ottawa medical students. The survey included both quantitative items including an adapted Pritzker list and qualitative responses to eight open ended questions on professionalism at the Faculty of Medicine, University of Ottawa. All analyses were performed using SAS version 9.1 (SAS Institute Inc. Cary, NC, USA). Chi-square and Fischer’s exact test (for cell count less than 5) were used to derive p-values for categorical variables by level of student learning.ResultsThe response rate was 45.6% (255 of 559 students) for all four years of the curriculum. 63% of the responses were from students in years 1 and 2 (preclerkship). Students identified role modeling as the single most important aspect of professionalism. The strongest curricular recommendations included faculty-led case scenario sessions, enhancing interprofessional interactions and the creation of special awards to staff and students to “celebrate” professionalism. Current evaluation systems were considered least effective. The importance of role modeling and information on how to report lapses and breaches was highlighted in the answers to the open ended questions.ConclusionsStudents identify the need for strong positive role models in their learning environment, and for effective evaluation of the professionalism of students and teachers. Medical school leaders must facilitate development of these components within the MD education and faculty development programs as well as in clinical milieus where student learning occurs.

Atlas of Functional Neuroanatomy

Orientation Introduction Overview * Spinal Cord * Brainstem and Cranial Nerves * Diencephalon (Thalamus) * Cerebral Hemispheres * Ventricles and CSF * Basal Ganglia * Internal Capsule Functional Systems Introduction and Orientation Part I: Sensory Systems * Spinal Cord Sensory Nuclei * Somatosensory and Trigeminal pathways * Auditory System * Visual System Part II: Reticular Formation * Pain Modulation Part III: Motor Systems * Introduction * Spinal Cord Motor Nuclei and Reflexes * Cortical Descending Tracts (spinal and bulbar) * Brainstem Descending Tracts (rubro-, reticulo-, vestibulo-) * Vestibular Nuclei, Eye Movements and MLF * Motor Regulatory Systems * Cerebellum Neurological Neuroanatomy * Introduction * Blood Supply to Brain * Thalamic Nuclei and connections * Brainstem Histology * Spinal Cord cross-Sections Limbic System * Introduction * Limbic Lobe * Limbic System: Noncortical * Hippocampal Formation * Amygdala * Limbic Diencephalon * Hypothalamus and Medial Forebrain Bundle * Olfactory System * Basal Forebrain * Limbic Synthesis Annotated Bibliography Glossary

Axonal projection patterns visualized with horseradish peroxidase in organized cultures of cerebellum

Abstract Neurons of the cerebellum and brain stem region of organotypic cultures were injected intracellularly with horseradish peroxidase. The axonal pattern was analyzed for the three cell types studied—Purkinje neurons, deep cerebellar neurons, and brain stem neurons. There was a consistent pattern for each cell type. The axon of the Purkinje neuron was uniform in diameter throughout, sometimes with one recurrent collateral, and within the deep nuclear region branched to produce a terminal field with many axon bulbs measuring 2–4 μm in diameter. The deep cerebellar neuron gave rise to a single axon which branched into a number of major axons, most of which coursed for long distances along the margin of the cortical region. Where the cortical region was separated off from the deep nuclear area, the axon of the deep cerebellar neuron branched and many axons coursed through the intervening zone to the cortex. The terminals in the cortical region were seen either as expansions along the fibre or as grape-like clusters on small side branches of the axons. The brain stem neuron had multiple axons which branched profusely and produced a system of fine-calibre varicose fibres, many of which coursed far into the outgrowth region. This study characterized the distribution of the axons of each neuron type. The results corroborate the fibre patterns seen in the living, stained and fluorescence studies of these cultures. The axon pattern for each neuron type resembles that of the corresponding neuron in the animal. These results will be correlated with the electrophysiological studies of the connections formed by the same neurons in sister cultures.

Electrophysiological and pharmacological studies of the inhibitory projection from the cerebellar cortex to the deep cerebellar nuclei in tissue culture

Abstract In explant cultures of mouse cerebellum, short latency inhibitions can be recorded from neurones in the deep cerebellar nuclei after electrical stimulation in the cortical region. The responsible projection appears to originate from Purkinje cells and to be monosynaptic to cells in deep nuclei. In many cases, the inhibition is followed by a rebound excitation which has been attributed to a disinhibition. Known blockers of synaptic inhibition (bicuculline, bicuculline methiodide, picrotoxin and strychnine) were added to the perfusing solution, for study of their effects on the evoked inhibition and on depressions of activity by iontophoretically applied glycine and γ-aminobutyrate. The results indicate that γ-aminobutyrate is probably the transmitter responsible for the synaptic inhibition. The experiments demonstrate the reproducibility of a central nervous system pathway in tissue culture and the ease of pharmacological manipulation of such a model system. The model has promising applicability for the study of synaptic mechanisms and as a test substrate for the interaction of drugs with a γ-aminobutyrate mediated pathway, particularly where the study of such substances is difficult in vivo.

Formation of medical student professional identity: categorizing lapses of professionalism, and the learning environment

BackgroundAcquiring the values of medical professionalism has become a critical issue in medical education. The purpose of this study was to identify lapses in professionalism witnessed by medical students during their four year MD curriculum, and to categorize, from the students’ perspective, who was responsible and the settings in which these occurred.MethodsAn electronic survey, developed by faculty and medical students, was sent to all students with two email reminders. It included quantitative responses and some open-ended opportunities for comments. All analyses were performed with SAS version 9.1.ResultsThe response rate was 45.6% (255 of 559 students) for all four years of the medical school curriculum. Thirty six percent of students had witnessed or been part of an exemplary demonstration of professionalism; 64% responded that they had witnessed a lapse of professionalism. At the pre-clerkship level, the most frequent lapses involved students: arrogance (42.2%), impairment (24.2%), followed by cultural or religious insensitivity (20.5%). At the clerkship level of training, where students are exposed to real clinical situations, the lapses involved primarily faculty (including preceptor and clinician) or other staff; these included arrogance (55.3%), breach of confidentiality (28.3%), and cultural or religious insensitivity (26.6%); impairment involved mostly students (25.5%). These findings are analyzed from the perspective of role modeling by faculty and in the context of the learning environment.ConclusionsMedical students witnessed a lapse of professionalism involving both fellow students as well as faculty and administrative staff, in several domains. Results from this study emphasize the importance of role modeling and the need for faculty development, to improve the learning environment. This study adds to the limited emerging literature on the forces that influence medical student professional identity formation.

Patterns of functional synaptic connections in organized cultures of cerebellum

Abstract Organized cultures of mouse cerebellum with separated regions containing cortical, deep nuclear neurons and brain stem neurons from the peduncular zone were used for electrophysiological studies of axonal projections and synaptic interactions. Responses of single neurons of each of the regions were recorded extracellularly and intracellularly during localized electrical stimulation of other parts of the explant, and indicated extensive synaptic interactions. Cortical stimulation inhibited deep nuclear neurons, apparently monosynaptically, and frequently caused antidromic activation of these cells. Synaptic responses of brain stem neurons to cortical stimulation were usually excitatory, but these were often succeeded by inhibitory potentials. Since brain stem cells were often antidromically activated, the excitatory synaptic responses may be mediated by collaterals of antidromically stimulated brain stem axons. Stimulation of the deep nuclear region could evoke inhibitory or excitatory potentials in cortical neurons, the most frequent response being an excitatory postsynaptic potential which was followed in about 2 ms by an inhibitory potential. Most excitatory and some inhibitory postsynaptic potentials followed high frequency stimulation with constant latencies. The results indicate that within these cultures there are rich synaptic interconnections, many of which follow patterns resembling those seen in the intact brain. The monosynaptic inhibitory projection from the cortex to the deep nuclei and collateral inhibition by Purkinje cell axons appear to be features of cerebellar function that are reproduced in this culture model. In addition, a projection from the deep nuclei to the cortex recently described in the intact cerebellum is also present in the cultures and gives postsynaptic potential responses typical of excitatory afferents to the cerebellar cortex. Such cultures appear useful as an experimental model for the study of synaptic mechanisms or the effects of drugs in the mammalian CNS.

Catecholamine Neurons of the Central Nervous System in Organotypic Culture

A standardized dissection has been designed to produce explants from the locus coeruleus of the newborn mouse brain. This area, termed the peduncular region, may be explanted with or without cerebellar neurons. Organotypic cultures with peduncular cells contain a cluster of 20-50 (or more) closely-packed large neurons, characterized by intracellular refractile granules in the living state. When treated with the glyoxylic acid method, somata of the granule-containing neurons exhibited catecholamine fluorescence, and a profuse plexus of varicose fluorescent fibers permeated the explant and its outgrowth. Intracellular staining of these cells with horseradish peroxidase demonstrated bipolar and multipolar neurons (25-30 micrometers), with stout dendrites and varicose axons. Granule-containing neurons stained for acetylcholinesterase. Electron microscopically, large dense granules were seen, which appear to correspond to the granules seen in living neurons. Cultures with these cells also have a high concentration of catecholamines in the medium. It is concluded that the granule-bearing neurons of the living culture are in fact neurons of the locus coeruleus.

A Morphologic Study of the Effects of LSD on Neurons in Cultures of Cerebellum

This study was undertaken to examine the possible cytologic action of LSD-25, lysergic acid diethylamide, on nervous tissue. Organotypic cultures of mouse cerebellum were exposed to LSD in their nutrient medium for periods up to 53 hours. Light-microscopically, at a dose of 10-3 M, coarse granules developed in the cytoplasm of mature neurons and in the cytoplasm of cells in the outgrowth region. Electron microscopy of these LSD-induced changes in the neurons revealed that the major qualitative change was the development of dense bodies, i.e. lysosomes. After several hours of exposure, these became heterogeneous dense bodies, HDBs, complex and varied in composition. The synaptic junction and other cell organelles were not altered morphologically. It was concluded that the cytologic site of action of LSD is the lysosomal system. Since it is known that LSD enters the cell, the possible site of interaction between the drug and the lysosomal system of the cell was considered. Two hypotheses were advanced in an attempt to correlate the effects on the lysosomal system of neurons and the known alterations in behaviour produced in man and animals by LSD: (i) an increase of endocytosis, and/or (ii) a shift of the internal metabolism of the cell. Either situation could result in an alteration of the excitability characteristics of a neuron.

Three-dimensional cultures of fetal mouse cerebral cortex in a collagen matrix

A 3-dimensional tissue culture system for fetal mouse cerebral cortex was devised in order to study neuronal migration in vitro. The dorsolateral cerebral mantle of E16 mouse was dissected into slices of 250-350 microns. Explants were embedded in a matrix formed of thin layers of collagen gel above and below the tissue. The optimal conditions for maintaining explant survival within the matrix included (1) placing the explants on membrane inserts with large (70 microns) pores which permits access of nutrient to the cultures from below as well as from above, and (2) intermittent exposure of the explants to ambient oxygen (20% O2 with 5% CO2) by partially covering the upper surface with medium and placing the cultures on a rocking platform. Thickness measurements of serially sectioned intact cultures at 6 days in vitro ranged from 128 to 210 microns (average: 172 microns). In intact explants, maintained for up to 14 days in vitro, the preservation of neurones, neuronal subtypes and glia was confirmed with immunofluorescence staining for neurone-specific nucleoprotein (NeuN), microtubule-associated protein (MAP-2), a glutamate receptor subunit (GluR 1), GABA and glial fibrillary acidic protein (GFAP) respectively. Some cortical differentiation was obtained in vitro, at 6 days, with the development of upper and lower cortical layers, similar to that seen in an P1 animal.