Recent Publications by CFE Educators

In decerebrate cats, electrical stimulation of nucleus raphe magnus (NRM) of the medulla produced marked inhibition of spinal neurons in lumbosacral dorsal horn. Only neurons with high threshold inputs were inhibited. These cells were located in lamina I and in or near laminae V and VI. The duration of inhibition produced was related to the stimulus train length. An ipsilateral lesion of the dorsolateral funiculus at L1 markedly reduced the inhibition of neurons caudal to the lesion. Although NRM stimulation was the most effective, inhibition from more lateral sites could be obtained at higher stimulus intensities. NRM induced inhibition is probably mediated by a direct projection via the dorsolateral funiculus to spinal dorsal horn laminae I, II, V and VI. The results are discussed in relation to proposed mechanisms underlying the analgesia produced by NRM stimulation.

This study examined the hypothesis that descending inhibitory pathways from brain stem to spinal cord mediate the analgesic effect of both electrical brain stimulation and morphine. In the first set of experiments, the effect of subtotal midthoracic spinal cord lesions on the analgesic effect of electrical stimulation in the periaqueductal gray matter of the rat was examined. In the second, the effect of similar cord lesions on the analgesic effect of intraperitoneal morphine was studied. In both cases, a lesion of the dorsal part of the lateral funiculus (DLF) reduced or abolished the analgesia of the hindlimbs. Analgesia of the forelimbs was unaffected. Lesions of the dorsal columns, which include the corticospinal tract, or lesions of the ventral part of the lateral funiculus had no effect on analgesia. It is concluded that an inhibitory pathway, which descends in the dorsal part of the lateral funiculus and which probably originates in the nucleus raphe magnus of the medulla, mediates the descending control found in both morphine and stimulus-produced analgesia.

Characteristics of best and worst clinical teachers in medicine were described by a random sample of faculty, residents and third- and fourth-year medical students at the University of Washington. The responses were factor analyzed and examined to determine whether the ratings were influenced by professional role (faculty, resident, student), faculty department (surgical, medical, basic science) and teaching method (formal in-patient, formal ambulatory, formal didactic, and informal teaching.)

Neurons in ventromedial medulla, including the nucleus raphe magnus, project to trigeminal nucleus caudalis and, via the dorsolateral funiculus, to spinal dorsal horn. The terminals of this descending system are in loci containing cells responsive to noxious stimuli. Electrical stimulation of nucleus raphe magnus selectively inhibits spinal dorsal horn neurons that respond to noxious stimuli. These neurons are located near the anatomically demonstrated terminals of this descending system. Dorsolateral funiculus lesions block this descending inhibition of spinal neurons as well as the analgesic action of morphine. This evidence supports the hypothesis that this neuron population mediates the analgesia produced by opiates and electrical stimulation of certain diencephalic and brainstem sites.

One side of the lumbar enlargement in adult cats was partially deafferented by cutting all dorsal roots caudal to L3 with the exception of the S1 dorsal root. At various times after the roots had been sectioned, the response of dorsal horn cells to natural and electrical stimuli applied to the leg and flank were recorded through extracellular glass microelectrodes. When animals were examined up to 24 h after this partial deafferentation, no cells were located in a region between segments L4 and 5 which responded monosynaptically to cutaneous stimulation on the leg. By one week, cells began to appear in the L4-5 region which responded monosynpatically to peripheral stimuli. The numbers of these newly connected cells seemed to have stabilised by 1 month after the partial deafferentation, but the properties of these cells were abnormal in 6 ways. The location of the receptive field of the cells was characteristic either of the S1 dermatome or of segments rostral to L4. Some cells had double receptive fields, one on the leg and one of the abdomen. The size of the receptive field varied more than is observed in normal intact dorsal horn. In particular, certain cells had unusually small recpetive fields with abrupt edges and no associated inhibitory fields. The cells receive less convergence from high treshold afferents than normally observed. Associated inhibitory fields were rarely encountered. Habituation was observed and in some cells with doulbe receptive fields the response o onet area habituated while the response to the other area was unaffected. Slow wave recording on the surface of the cord showed that the effect of peripheral stimulation of the S1 dermatome spread far more extensively on the chronically deafferented side of the cord than it did on the intact side or in an intact cord. It was concluded that following partial deafferentation, the remaining afferents can establish connection with deafferented cells but the data presented did not allow a conclusion as to whether the new connections were produced by sprouting or by the unmasking of existing connections.

The development of a program designed to improve the teaching effectiveness of faculty members of a new Introductory Psychopathology course at the University of Washington School of Medicine is described. Two consultants from the Office of Research in Medical Education worked closely with the faculty in designing the evaluation program during the preparation of the course. The literature on lecture effectiveness is reviewed, as are existing instructional evaluation instruments. The integration of this information and the needs of the involved faculty produced a lecture observation schedule designed to facilitate the observation of a lecture and the immediate feedback which followed each of the 15 lectures evaluated. The process of using this instrument to assist the faculty in self-improvement is discussed. While the specific evaluation method described may not be appropriate for all situations, it may serve as a model for the development of similar programs in other settings.