Effectiveness of the "teaching the teachers" diagnostic US training program.

RATIONALE AND OBJECTIVES: The "Teaching the Teachers" training program was meant to establish standardized ultrasound education programs worldwide, reaching the largest possible number of physicians. The authors performed this study to evaluate the results of this training. MATERIALS AND METHODS: An open-ended test question format (ie, uncued testing) that would evoke responses from physicians in a manner ensuring the highest fidelity with a real clinical setting was selected. An examination was administered at the beginning and the end of the program and then again 6 months later to assess baseline knowledge, changes in knowledge, and knowledge retention, respectively. RESULTS: Scores on entry and end-of-program examinations were available for 112 participants. The mean entry test score was 35%, and the mean end-of-program examination score was 73%. All changes in scores were statistically significant (P < .001) as determined with paired t tests. Follow-up examinations were available for 27 of the 112 participants at the time of the analysis. On these examinations, mean total test scores increased by nearly 4 percentage points. Although follow-up test scores were available for only 27 participants, these mean test scores were comparable to those reported for the entire group on the end-of-program examination. CONCLUSION: The examinations administered at the end of the 3-month program showed marked improvement compared with the baseline assessment. That this improvement remained stable over 6 months indicates the success of the educational process.

The impact of a hydroelectric power plant on the sediment load in downstream water bodies, Svartisen, northern Norway.

When the Svartisen hydroelectric power plant was put into operation, extensive sediment pollution was observed in the downstream fjord area. This paper discusses the impact of the power plant and the contribution from various sources of sediment. Computation of the sediment load was based on samples collected one to four times per day. Grain size distribution analyses of suspended sediments were carried out and used as input in a routing model to study the movement of sediments through the system. Suspended sediment delivered to the fjord before the power station was constructed was measured as 8360 metric tons as an annual mean for a 12-year period. During the years 1995-1996 when the power plant was operating, the total suspended load through the power station was measured as 32609 and 30254 metric tons, respectively. Grain size distribution analyses indicate a major change in the composition of the sediments from 9% clay before the power plant was operative to 50-60% clay afterwards. This change, together with the increase in sediment load, is believed to be one of the main causes of the drastic reduction in secchi depths in the fjord. The effect of the suspended sediment load on the fjord water turbidity was evaluated by co-plotting secchi depth and power station water discharge. Measurements during 1995 and 1996 showed that at the innermost of these locations the water failed to attain the minimum requirement of 2 m secchi depth. In later years secchi depths were above the specified level. In 1997 and 1998 the conditions improved. At the more distal locality, the conditions were acceptable with only a few exceptions. A routing model was applied to data acquired at a location 2 km from the power station in order to calculate the contributions from various sediment sources. This model indicated that the contribution from reservoir bed erosion dominated in 1994 but decreased significantly in 1995. Future operation of the power station will mostly take place with a high water level in the reservoir and is likely to result in acceptable water quality in the fjord. However, during periods of low drawdown, sediment pollution may again become a problem.

Split-brain basics: relevance for the concept of one's other mind.

Frontal and horizontal sections of the cerebrum make plain that with a few exceptions (pineal, pituitary) all structures are paired. Hemicerebrectomy has made clear that only one member of the hemispheric pair suffices to sustain the sentiments, emotions, memories, and intentions both conscious and unconscious that we call in the aggregate, mind. That the anatomical duality can sustain a duality of mentation is evident from not only the split-brain results in all species examined but also the results of appropriate testing of anatomically intact individuals. There is no physiological evidence for a plurality of mind beyond duality. Psychoanalytic views of mind can benefit from revision in the light of the split-brain studies. But such revisions seem slight compared with improvements needed in the views prevalent among most other psychologic and philosophic theorists.

My developing understanding of Roger Wolcott Sperry's philosophy.

Reviewed are some of the dramatic experimental results and penetrating analyses characterizing the career of Roger Sperry. These require that we seriously consider his opinions regarding matters not yet testable, especially regarding the brain/mind relationships. His opinions include first, that a worthwhile understanding of brain function requires a biological explanation of consciousness; second, that mental properties described by him as "overall pattern effects in brain dynamics" can govern neuronal traffic at the cellular level by virtue of "mental forces'; and third, that further development of this outlook can provide a scientific basis for moral values. Discussion here is restricted to the first two of these points, urging that most criticisms of them arise largely from semantic confusions inherited from our past. Particular emphasis is placed on distinguishing mind from soul, thus totally separating the brain-onto-mind mapping problem from the nexus problem inherited from Descartes. Taken here is a physicalist position regarding mind, together with agnosticism regarding the nonmaterial.

Different psychological status in the two hemispheres of two split-brain patients.

Questions of a psychological nature were presented to two split-brain patients from the California series encouraging each hemisphere to respond simultaneously and independently. The responses of both patients indicated that their hemispheres were responding independently. For the first patient, his right hemisphere appeared to be more disturbed than his left by childhood memories of being bullied. The right hemisphere of the second patient seemed to regard himself more positively, but it also seemed to feel more negative emotions such as loneliness and sadness. We discuss the possible significance of the findings.

Some neurophysiologic aspects of consciousness.

An anatomico-physiologic approach to consciousness is facilitated by recognizing that the various meanings of consciousness have in common a crucial core C variously called subjectivity, awareness, consciousness-as-such, or consciousness per se. A sharp distinction is made between the property C and the contents of consciousness, partial loss of which is typical of cerebro-cortical lesions. The neuronal mechanism producing subjectivity also acts as an attention-action coordinator, hence must have specific connectivity requirements. These requirements are best met by the thalamic intralaminar nuclei (ILN). Whereas large lesions elsewhere leave C undisturbed, quite small bilateral lesions in ILN engender immediate unresponsiveness. This combination of anatomic and neurologic evidence is bolstered by a variety of physiologic evidence leading to the conclusion that further investigations of the ILN, and their interaction with lower centers as well as cerebral cortex, are most apt to yield a better understanding of consciousness.

Does cognition in the disconnected right hemisphere require right hemisphere possession of language?

It has been asserted at times that the human right hemisphere is cognitively inferior to that of a chimpanzee or even a monkey. Related is the even stronger claim that human consciousness, as well as cognition, requires language. These claims are discussed, and counterexamples are presented from both split-brain subjects and patients hemispherectomized in adulthood after customary development as righthanders.

On the neurophysiology of consciousness: Part II. Constraining the semantic problem.

The main idea in this series of essays is that subjective awareness (more precisely, what I call C) depends upon the intralaminar nuclei of each thalamus (hereafter, ILN). This implies that the internal structure and external relations of ILN make subjective awareness possible. An array of material relevant to this proposal was briefly reviewed in Part I (Bogen, 1995). This Part II considers in more detail some semantic aspects and a bit of philosophic background as these pertain to propositions 0, 1, and 2 of Part I. Part II should be read in conjunction with Part I.

On the neurophysiology of consciousness: I. An overview.

How certain neural mechanisms (Mc) momentarily endow with subjective awareness (C) percepts and affects represented elsewhere is more likely to be clarified when structures essential to Mc are identified. The loss of C with bilateral thalamic lesions involving the intralaminar nuclei (ILN) contrasts with retention of C after large cortical ablations depriving C of specific contents. A role of ILN in the perception of primitive (i.e., not cortically computed) sensations is suggested by their afference of directly ascending pathways. A role for ILN in awareness of cortical activity is suggested by their widespread afference from cortex, a property shared with striatum. A role for ILN in volition is suggested by their heavy projection to striatum. Unlike striatum, ILN also project widely to almost all neocortex, enabling an effect on ideation; this last property is in common with other structures (e.g., locus coeruleus) but none of them has the same direct cortical afference. And passage through the reticular nucleus (nRt) of ILN efferents to cortex could impact the attention-selective action of nRt. It is suggested that the quickest route to a better understanding of C involves more intensive study of ILN. No other structure seems, in the light of our current knowledge, a more likely site for Mc.

Trends in length of stay and rates of readmission in Massachusetts: implications for monitoring quality of care.

In this study, we examined lengths of stay and readmission rates for all Medicare patients discharged from Massachusetts acute care hospitals from October 1982 through September 1986. Using multivariate time series models, we controlled for case mix and assessed trends over time and the impact of prospective payment on lengths of stay and rates of readmission within 7, 14, and 30 days of discharge. We examined patterns for patients overall and for those admitted initially with one of several specific medical conditions or for a surgical procedure. Over the four years, lengths of stay decreased by 25% overall and by 12% to 38% for the individual conditions studied (all p less than .05). A small part of this decrease was associated with prospective payment. Overall readmission rates within 7 and 14 days increased by approximately 10% (p less than .05), although the increase was not statistically associated with prospective payment. Readmission rates for individual medical and surgical conditions were not significantly changed. Further study should assess whether the change in overall rates reflects lower quality care.

Completeness of callosotomy shown by magnetic resonance imaging in the long term.

Six individuals who had complete cerebral commissurotomy for medically intractable epilepsy participated in a magnetic resonance imaging study 20 or more years postoperatively. In all cases the completeness of callosotomy was clearly demonstrable. The status of the anterior commissure, cut in all six, could not be confirmed with the same confidence.

Alexithymia and the split brain: VI. Electroencephalographic correlates of alexithymia.

Electroencephalographic recordings of eight corpus callosotomy patients and eight precision-matched control subjects were obtained as subjects watched a film symbolically depicting death. A content-analytic measure of alexithymia was regressed on eight auto-spectral alpha-band intensity averages and on subsets of alpha-band coherence averages. Results were interpreted on the basis of three possible mechanisms of alexithymia: (1) Alexithymic subjects had more right-temporal alpha-band intensity, suggesting inadequate understanding of the film. (2) A possible lack of inner speech in alexithymics was suggested by their relative alpha abundance of the left frontal and left temporal channels but left parietal alpha desynchronization, and by their lower left frontotemporal but higher left parietofrontal and left parietotemporal coherences. (3) Alexithymic subjects had higher right frontal-left parietal and left frontal-left parietal coherences, suggesting possible interhemispheric inhibition of expression. Expressive subjects had higher right frontal-left temporal (and homologous interhemispheric frontal, parietal, and frontal) coherences, suggesting interhemispheric facilitation of verbal expression.

Creativity and the corpus callosum.

A duality of mind is readily demonstrable in split-brain humans, and evidence is steadily accumulating that ongoing interhemispheric communication is incomplete in the intact brain. It is now certain that the corpus callosum can transfer high-level information from one hemisphere to another. When we take into account the well-established principle of hemispheric specialization, added to the impressive normality of split-brain humans in ordinary social situations, a physiologic explanation for at least some forms of creativity seems close at hand. What is required is a partial (and transiently reversible) hemispheric independence during which lateralized cognition can occur and is responsible for the dissociation of preparation from incubation. A momentary suspension of this partial independence could account for the illumination that precedes subsequent deliberate verification. From this point of view, we can understand better the opinion of Frederic Bremer, who wrote years ago that the corpus callosum subserves "the highest and most elaborate activities of the brain"--in a word, creativity.

Alexithymia and the split brain. V. EEG alpha-band interhemispheric coherence analysis.

Electroencephalographic (EEG) recordings were obtained while 6 completely commissurotomized patients, 2 partially commissurotomized patients, and 8 precision-matched normal control subjects watched 4 times a film symbolically depicting death. Our hypothesis was that alexithymia--a diminished capability to verbally express moods, symbols, and feelings--would be greater for patients because loss of cerebral commissures reduces interhemispheric communication, separating right-hemisphere-dependent affective understanding and left-hemisphere-dependent verbalization. Path and covariance structure analyses confirmed that callosotomy decreased alpha-band EEG coherences (after adjustment for mean intrahemispheric coherence) between pairs of scalp electrode channels placed homologously over frontal, parietal, and temporal lobes of the brain. This result occurred both for an index of interhemispheric coherence and for a latent variable indicated by the 3 adjusted coherences. Reduced levels of interhemispheric coherence in turn increased alexithymia, for an overall index and for a latent variable indicated by lexical-level content-analytic measures of verbal responses to the filmic stimulus.