Underwater channel estimation exploiting multipath feature morphology

Real-time accurate channel estimation has been an ongoing challenge because of diverse oceanic events that cause rapid fluctuations of high-energy multipath activity across the delay spread. This work leverages current compressed sensing and sparse optimization techniques with topological signal processing to improve estimation time and localize channel estimation to salient parts of the delay spread. This work improves the estimation time by tracking the channel as a union of overlapping multipath and other scattering events, which are modeled as "feature braids" in the delay-time domain. A channel feature braid may be intuitively visualized as the topologically connected trajectory of a group of channel delay taps, which represent the support of dominant or persistent scattering events, e.g., surface bounce multipath scattering. We present algorithms that harness support-constrained mixed norm optimization techniques to track the evolving support of channel feature braids. We validate our channel feature tracking algorithm independently in experimental field data as well as BELLHOP channel simulations across a diversity of oceanic conditions. This work shows that braiding used in estimation can improve estimation time and track high-energy events that develop within the delay vs time channel representation.

Prophylactic mesh used in ileal conduit formation following radical cystectomy: a retrospective cohort

PURPOSE

Given the difficulty of durable repairs, there is continued interest in hernia prevention. One emerging prevention technique for parastomal hernias is prophylactic mesh placement, whereby mesh is inserted during the index procedure as hernia prophylaxis. We evaluated our experience using prophylactic mesh when creating an ileal conduit.

METHODS

We retrospectively reviewed patients undergoing robotic cystectomy with ileal conduit from 6/2010 to 8/2017. Patient demographics and operative/perioperative outcomes were documented. We evaluated hernia recurrence using postoperative computed tomography scanning or physical exam. Prophylactic mesh was inserted at the operating surgeon's discretion using a synthetic resorbable or biologic mesh.

RESULTS

During the study period, 38 patients underwent robotic-assisted cystectomy with ileal conduit formation. Average patient age was 68 years, with 28 (74%) male and 35 (92%) Caucasian patients. Three patients (8%) required conversion to open, and one patient (3%) had a concomitant colorectal resection. Thirty-one (88%) patients had postoperative computed tomography scanning. Prophylactic mesh was used in 18 patients (47%) in a retrorectus position. Of these, 15 (83%) patients had synthetic resorbable mesh and 3 (17%) patients had biologic mesh. At average follow-up of 21 months, one hernia recurred (5%) in a patient without mesh placement at the time of ileal conduit. At an average follow-up of 11 months, there have been no recurrences and no mesh-related complications in the prophylactic mesh group.

CONCLUSIONS

Using prophylactic mesh in ileal conduit, creation is feasible and may decrease the parastomal hernia formation rate. Further study of using synthetic resorbable and biologic meshes for hernia prophylaxis is warranted.

Language abnormality in deaf people with schizophrenia: a problem with classifiers

INTRODUCTION

Although there is evidence for language abnormality in schizophrenia, few studies have examined sign language in deaf patients with the disorder. This is of potential interest because a hallmark of sign languages is their use of classifiers (semantic or entity classifiers), a reference-tracking device with few if any parallels in spoken languages. This study aimed to examine classifier production and comprehension in deaf signing adults with schizophrenia.

METHOD

Fourteen profoundly deaf signing adults with schizophrenia and 35 age- and IQ-matched deaf healthy controls completed a battery of tests assessing classifier and noun comprehension and production.

RESULTS

The patients showed poorer performance than the healthy controls on comprehension and production of both nouns and entity classifiers, with the deficit being most marked in the production of classifiers. Classifier production errors affected handshape rather than other parameters such as movement and location.

CONCLUSIONS

The findings suggest that schizophrenia affects language production in deaf patients with schizophrenia in a unique way not seen in hearing patients.

Flashbulb memories in patients with temporal lobe epilepsy

PURPOSE

Flashbulb memories (FMs) are vivid and stable autobiographical memories associated with learning surprising news of high emotional impact. Patients with temporal lobe epilepsy (TLE) can have autobiographical memory deficits. This is the first investigation of FMs in TLE applying a consistency measure of FM quality controlling for confabulation.

METHOD

A sample of 12 patients with TLE and a matched group of 15 healthy controls (HCs) were tested on an FM test including a retest procedure. Scores of FM consistency were obtained by comparing answers across both testing occasions.

RESULTS

In patients with TLE, FM consistency scores were significantly lower than in HCs. Exploratory subgroup analyses revealed FM deficits in both patients with left TLE and patients with right TLE compared with HCs.

CONCLUSION

The present study indicates that the FMs of patients with TLE are less consistent than those of healthy control subjects. Future investigations with larger samples are desirable, especially regarding separate analyses of patients with left TLE and patients with right TLE.

Maternal and infant nutritional supplementation practices in Ireland: implications for clinicians and policymakers

This prospective Irish observational study examined maternal and infant nutritional supplement use. From an initial sample of 539 mothers recruited from the Coombe Women and Infants University Hospital in Dublin (during 2004-2006), 450 eligible mothers were followed up at 6 weeks and 6 months postpartum. Only 200 women (44.4%) complied with peri-conceptional folic acid at the recommended time with strong social patterning associated with its uptake. Almost 10% of the sample (n = 44) consumed a combined multivitamin and mineral supplement during pregnancy. A vitamin D-containing supplement was provided to only 5 (1.1%) and 15 (3.3%) infants at 6 weeks and 6 months, respectively. A national guideline that advises on adequate and safe use of both vitamin and multivitamin supplements during pregnancy with particular reference to vitamin A and D is warranted. Given the re-emergence of rickets in Ireland, and the reported morbidities associated with vitamin D insufficiency, promoting and monitoring compliance with 200 IU [5 microg] daily vitamin D supplements to all infants particularly those from higher risk groups from birth to 1 year, should be a public health priority.

Confabulation in schizophrenia and its relationship to clinical and neuropsychological features of the disorder

BACKGROUND

A form of confabulation has been documented in schizophrenia and appears to be related to the symptom of thought disorder. It is unclear whether it is associated with the same pattern of neuropsychological deficits as confabulation in neurological patients.

METHOD

Thirty-four patients with chronic schizophrenia, including those with and without thought disorder, and 17 healthy controls were given a fable recall task to elicit confabulation. They were also examined on a range of executive, episodic and semantic memory tests.

RESULTS

Confabulation was seen at a significantly higher rate in the schizophrenic patients than the controls, and predominated in those with thought disorder. Neuropsychologically, it was not a function of general intellectual impairment, and was not clearly related to episodic memory or executive impairment. However, there were indications of an association with semantic memory impairment.

CONCLUSIONS

The findings support the existence of a form of confabulation in schizophrenia that is related to thought disorder and has a different neuropsychological signature to the neurological form of the symptom.

Is there a schizophasia? A study applying the single case approach to formal thought disorder in schizophrenia

It has been suggested that formal thought disorder, the incoherent speech of schizophrenia, may involve a language disturbance among other abnormalities, or even be a form of dysphasia. Six patients with and seven without formal thought disorder were evaluated on an aphasia test battery. Spontaneous speech was also analysed using Brief Syntactic Analysis. Poor performance on the aphasia test battery was found to be associated with general intellectual impairment but not with formal thought disorder. Naming was preserved in both groups. Patients with formal thought disorder, but not those without, produced semantic errors in their spontaneous speech, and these were unrelated to general intellectual status. The disorder of language in formal thought disorder thus appears to be one of expressive semantic abnormality, which, however, spares naming. Further analysis of two intellectually preserved patients suggested that formal thought disorder may be associated with an additional difficulty in constructing an appropriate model for generating one's own speech.

Effects of dietary protein on glomerular mesangial area and basement membrane thickness in aged uninephrectomized dogs

The primary objective of this study was to determine the effects of diets containing 18% or 34% protein on glomerular mesangial area (GMA) and basement membrane thickness (GBMT) in uninephrectomized aged dogs. A secondary objective was to determine the combined effects of aging and uninephrectomy on GMA and GBMT in dogs. Ten clinically healthy, pure-bred dogs were unilaterally nephrectomized at about 8 y of age. After 2 mo, 5 dogs were fed an 18% protein diet and 5 dogs were fed a 34% protein diet for 48 mo. At month 48, the dogs were euthanized and the remaining kidney was collected. Samples of kidney from both times of collection were used to measure GMA and GBMT using electron microscopy. The effects of diet on GMA and GBMT were analyzed (student's t-test) using necropsy/nephrectomy score ratios. The effects of time-nephrectomy were determined by comparing nephrectomy values for GMA and GBMT with necropsy values (paired t-test). Dogs fed 34% dietary protein did not have a significant increase in GMA and GBM thickness when compared to dogs fed the 18% protein diet. A significant increase in GMA and GBMT occurred with time-nephrectomy (P = 0.011 and 0.018, respectively). Although dietary protein intake was not a significant factor in causing structural changes to glomeruli in uninephrectomized aged dogs, the power to detect a difference was low. However, significant effects of aging and nephrectomy were detected despite the low power of the study. These results suggest that the increases in GMA and GBMT that occur over time are not markedly influenced by dietary protein intake. However, subtle protein effects cannot be eliminated as a possibility based on this study.

Language in schizophrenia and its relationship to formal thought disorder

BACKGROUND

Although poor language test performance has been documented in schizophrenia, its relationship to formal thought disorder remains unclear.

METHOD

Forty schizophrenic patients were administered eight language tests and, under blind conditions, rated for formal thought disorder. Measures of general intellectual function were also obtained.

RESULTS

Performance on all language tests was significantly correlated with the general intellectual measures. Three language test scores also showed significant correlations with formal thought disorder scores. Multiple regression and analysis of intellectually preserved patients suggested particular associations of formal thought disorder with semantic comprehension and picture description.

CONCLUSIONS

General intellectual impairment is an important determinant of poor language test performance in schizophrenia, but presence of formal thought disorder may also contribute. A higher-order semantic deficit may be particularly relevant to both linguistic impairment and formal thought disorder.

Basal cell carcinoma arising in a cleft lip repair scar

BACKGROUND

A case of basal cell carcinoma (BCC) developing in the repair scar of a cleft lip is presented.

OBJECTIVE

Primary BCCs arising in surgical scars are very rare and no known reported cases exist of a BCC developing in a surgically repaired cleft lip scar.

METHODS

A 69-year-old white man presented with a 5 mm primary BCC on his upper lip at the site of his cleft lip repair scar. The diagnosis was made by a tangential biopsy that showed an ulcerated BCC.

RESULTS

Review of the medical literature indicates that a scar may be an independent risk factor for developing BCC.

CONCLUSION

BCC may rarely arise in a cleft lip repair scar.

Is the mind a cauliflower or an onion? British insights into cognitive organization from the study of abnormal function

Clinical and normal psychology have had a long tradition of close interaction in British psychology. The roots of this interplay may predate the development of the British Psychological Society, but the Society has encouraged and supported this line of research since its inception. One fundamental British insight has been to consider the evidence from pathology as a potential constraint on theories of normal function. In turn, theories of normal function have been used to understand and illuminate cognitive pathology. This review discusses some of the areas in which clinical contributions to cognitive theory have been most substantial. As with other contributions to this volume, attempts are also made to read the runes and anticipate future developments.

Repeating without semantics: surface dysphasia?

We describe our investigations of MNA, who had a progressive, severe and global loss of semantic knowledge (semantic dementia). Her verbal vocabulary was restricted to a few common words and she was also unable to recognize common objects from sight. By contrast, she had a well-preserved digit span (7-8 digits). In this series of experiments, we focused on her ability to repeat lists and sentences in which familiarity, meaningfulness, morphology and syntactic structure were manipulated. In list repetition tasks, we found that MNA showed a reliable effect of phonological similarity, word frequency and stimulus lexicality, but was unaffected by linguistic complexity, word length, semantic coherence or the status of individual stimuli as "known" or "unknown". In sentence repetition, her performance was not influenced by any semantic variables. However, there was a substantial effect of the frequency of the constituent vocabulary, even for words outside the range of her retained vocabulary. The influence of syntax was restricted to minor effects of morphology. The phonemes of syllables and the syllables of words are bound by their co-occurrence rather than their meaning. We conclude that the phonological representation of words is functionally independent of the semantic system.

Dermatologist and electrologist perspectives on laser procedures by nonphysicians

BACKGROUND

As hair removal technology continues to evolve and new equipment comes to market, conflicts may develop between dermatologists and electrologists regarding the professional control and use of these devices.

METHODS

A total of 1004 Fellows of the American Academy of Dermatology and 719 electrologists from the southern United States were anonymously surveyed about clinical laser procedures (CLPs).

RESULTS

Compared to electrologists, dermatologists were more likely to support clinical laser regulations that placed licensed physicians in control (P =.001) and preferred that a delegating physician be physically present on the premises when CLPs were performed (P =.001). If a laser device was invented for permanent hair removal that was identical to traditional needle/probe electrolysis in every respect except energy type ("laser fiberoptic probe," LFP), electrologists were more likely than dermatologists to support independent use of this device by electrologists (P =.001). A greater percentage of electrologists from Texas, a state without electrolysis licensing, were more likely to support the unlicensed use of the LFP and CLPs than electrologists from states requiring electrolysis licensing.

CONCLUSIONS

These data are consistent with previously published literature and permit a greater understanding of the multiple attitudinal, regulatory, and ethical issues involved when considering delegated and independent CLPs by electrologists.

Accelerated forgetting in patients with epilepsy: evidence for an impairment in memory consolidation

Patients with epilepsy frequently complain of memory difficulties yet perform normally on standard neuropsychological tests of memory. It has been suggested that this may be due to an impairment of very long-term memory consolidation processes, beyond those normally assessed in the neuropsychological clinic. We carried out a prospective study of verbal memory over a long-term retention interval of 8 weeks in patients with epilepsy and in controls. Results were compared with performance on conventional tests of memory. Despite normal learning and retention over 30 min, patients with epileptic foci in the left temporal lobe performed disproportionately poorly on the long-term test compared with both patients with epileptic foci in the right temporal lobe and controls. Our findings provide evidence for an extended period of memory consolidation and point to the critical region for this process, at least for verbal material, in the left temporal lobe. The implications of our findings for clinical assessment and therapeutic management of patients with epilepsy are discussed.

Permanent and functional male-to-female sex reversal in d-rR strain medaka (Oryzias latipes) following egg microinjection of o,p'-DDT

Complete sex reversal of fish is accomplished routinely in aquaculture practices by exposing fish to exogenous sex steroids during gonadal differentiation. A variety of environmental chemicals are also active at sex steroid receptors and theoretically possess the potential to alter normal sexual differentiation in fish. However, in controlled environmental chemical exposures to date, only partial alterations of fish sexual phenotype have been observed. Here we report complete, permanent, and functional male-to-female sex reversal in the Japanese medaka (Oryzias latipes, d-rR strain) after a onetime embryonic exposure to the xenoestrogen o, p'-DDT. d-rR strain medaka are strict gonochorists that possesses both sex-linked pigmentation, which distinguishes genotypic sex, and sexually dimorphic external secondary sexual characteristics, which distinguish phenotypic sex. We directly microinjected the xenoestrogen o, p'-DDT into the egg yolks of medaka at fertilization to parallel the maternal transfer of lipophilic contaminants to the embryo. At 10 weeks of age, microinjected medaka were examined for mortality and sex reversal. A calculated embryonic dose of 511 +/- 22 ng/egg o, p'-DDT (mean +/- standard error) resulted in 50% mortality. An embryonic exposure of 227 +/- 22 ng/egg o, p'-DDT resulted in 86% (6 of 7) sex reversal of genetic males to a female phenotype (XY females). XY females were distinguished by sex-linked male pigmentation accompanying female secondary sexual characteristics. Histologic examination of the gonads confirmed active ovaries in 100% of the XY females. In 10-day breeding trials in which XY females were paired with normal XY males, 50% of the XY females produced fertilized embryos; this represents a comparable breeding success rate to normal XX females. Fertilized eggs produced from XY females hatched to viable larvae. These results clearly indicate that a weakly estrogenic pesticide, o, p'-DDT, when presented during the critical period of gonadal development, can profoundly alter sexual differentiation.

Ciguatoxin reduces larval survivability in finfish

Ciguatoxins are lipophilic polyether toxins which concentrate in the viscera and flesh of coral reef associated finfish (Hessel et al., 1960). In this study, we quantify the adverse effects of ciguatoxin on fish embryos by microinjection into the egg yolk of medaka (Oryzias latipis) embryos. Embryos microinjected with 0.1-0.9 pg/egg (ppb) of ciguatoxin exhibit cardiovascular, muscular, and skeletal abnormalities and those injected with higher levels (1.0-9.0 pg/egg) exhibit significantly reduced hatching success. The sensitivity of embryonic fish to direct oocyte exposure indicates that maternal transfer of low levels of ciguatoxin may represent an unrecognized threat to the reproductive success of reef fish and a previously undetected ecological consequence of proliferation of ciguatoxin-producing algae in reef systems increasingly impacted by human perturbations.

Prosopagnosia and structural encoding of faces: evidence from event-related potentials

Event-related brain potentials (ERPs) were recorded in response to unfamiliar faces and to houses from a severely prosopagnosic patient (PHD) and 24 control subjects. For all control subjects, faces elicited an enhanced negativity at lateral temporal electrodes (N170). This component was absent for PHD. Comparable results were obtained in response to inverted faces and houses. A selective deficit in face recognition is therefore reflected by abnormalities in ERP components specific to faces. As PHD was shown to have substantial deficits on tasks requiring the structural analysis of faces, these findings are consistent with the view that the N170 reflects processes involved in the structural encoding of faces, and may be a measure of selective impairments in the analysis of face components.

Exogenous retinoic acid during gastrulation induces cartilaginous and other craniofacial defects in Fundulus heteroclitus

Embryonic levels of retinoic acid (RA) and the response of cells to RA are critical to the normal development of vertebrates. To understand the effects of RA signaling in Fundulus heteroclitus, we exposed embryos to a range of RA concentrations of 2 h during gastrulation. Embryos exposed to low concentrations of RA (10(-10)-10(-7) M) develop normally, whereas those exposed to higher concentrations (5 x 10(-7)-10(-4) M) develop characteristic dose-dependent defects. We describe, in detail, four stages of development that represent morphological effects of RA on (1) cell death and defects in the brain, heart, and eye, (2) relative size and differentiation, (3) duplications of pectoral fins, and (4) deletions in craniofacial cartilage elements. Analysis of cartilaginous skeletal elements demonstrates distinct patterns of deletions in the neurocranium and pharyngeal skeleton in response to increasing concentrations of RA. In F. heteroclitus, RA treatment during gastrulation results in five highly consistent phenotypes, which we have incorporated into an index of embryonic RA defects. This index should be valuable in the genetic analysis of RA pathways and in evaluating chemicals that interfere with embryonic RA signaling.

Fin duplications and deletions induced by disruption of retinoic acid signaling

Retinoic acid (RA), a derivative of vitamin A, plays a critical role as a signaling molecule in axial patterning of vertebrates. Here we report that RA exposure of zebrafish (Danio rerio) and mummichog (Fundulus heteroclitus) embryos during gastrulation results in homeotic duplications of the pectoral fins in up to 94% of fish. We have observed three to four pairs of fins in an individual fish. Although some duplications are partial, many represent complete axial duplications of the pectoral girdle and fin and include coracoscapulae, proximal radials, and dermal fin elements. Fin duplications are observed only at a defined dose of RA. Inhibition of RA synthesis by exposure to citral during a narrow developmental window leads to fish which lack pectoral fins but can be rescued by addition of exogenous RA, suggesting that RA signaling is critical to fin specification during early development. The ability to consistently induce multiple fins in a large number of vertebrate embryos should contribute to the understanding of genetic regulation of the normal positioning of limbs during embryogenesis.

The neuropsychology of object constancy

There have been several proposals for the mechanism by which we are able to recognize an object across a number of viewpoints. Viewpoint-dependent accounts suggest that recognition may be based on an incremental transformation (e.g., mental rotation) strategy, while a variety of viewpoint-independent mechanisms for object recognition have also been proposed. Recent research in neurobiology, based on the two cortical visual systems account, suggest that the processes of viewpoint-dependent and viewpoint-independent object recognition may rely on separate anatomical regions, and that brain lesions may leave patients with selective access to particular types of representation. Evidence from a variety of neuropsychological disorders are reviewed to support the position that viewpoint-independent object recognition depends upon the integrity of occipitotemporal structures. In addition, it is suggested that viewpoint-dependent processes (perhaps depending on occipitoparietal structures) may supplement this primary system under nonoptimal circumstances.

Reconsidering the gospel according to group studies: a neuropsychological case study approach to schizophrenia

Individual patterns of performance on tests of: visual perception, language, executive function, memory, and face-processing, were examined in 10 schizophrenic patients who were preselected for having current WAIS IQ and premorbid NART IQ scores in the normal range. Although the patients showed some heterogeneity in the type, pervasiveness, and degree of cognitive impairment, a majority had severely impaired verbal recall and familiar face-naming. This contrasted with the low incidence and severity of impairment on tests of executive function, visual recall, recognition memory, naming, and unfamiliar faceprocessing. Contrasts between individual patients indicated that verbal recall and executive performance are independent in some patients and that memory appears to be the core deficit. The profile of impaired and preserved cognitive function revealed some important dissimilarities from the pattern that has emerged from group studies. Finally, face-naming correlated highly with the learning of unrelated paired associates, confirming a similarity with neurological patients who have person name anomia. It is suggested that both deficits might reflect a problem with learning ''meaninglessness'' associations; this interpretation is discussed with reference to a deficit at the level of the Supervisory Attentional System (Shallice, 1988).

Polar effects of lithium in the heart of the zebrafish Danio rerio

The molecular signalling mechanisms that are believed to govern the patterning of the heart early in embryonic development are not well understood. We have investigated the events which occur during patterning of the vertebrate heart by exposing gastrula stage zebrafish embryos to lithium, which is known to affect the phosphoinositol signalling pathway. Treatment of embryos at 50% epiboly (5.25 h after fertilization at 28.5°C) with 0.3 M LiCl for 5-15 min, results in embryos with defects which range from mild to severe, depending on the length of time the embryos are exposed to lithium. In the heart, defects appear progressively in the inflow tract, the sinus venosus and atrium. By using an antibody that recognizes an atrium-specific isoform of myosin, our results show that lithium treatment at gastrulation specifically affects the atrium and sinus venosus, and has little obvious effect on the ventricle. Defects induced by lithium differ from those induced by retinoic acid (RA) treatment of similarly staged embryos, and suggest that lithium and RA may affect the patterning signals important for establishment of the vertebrate heart by acting on different populations of cells or by influencing different patterning pathways.

Topographic amnesia: spatial memory disorder, perceptual dysfunction, or category specific semantic memory impairment?

A 60 year old patient, SE, who presented with a severe difficulty in finding his way around previously familiar environments and a mild prosopagnosia is described. SE had herpes simplex encephalitis resulting in selective right temporal lobe damage. He showed normal spatial learning, but was severely imparied in his ability to recognise pictures of buildings and landmarks. The disorder was not confined to the visual modality, but rather involved a loss of knowledge about famous buildings and landmarks when tested from their spoken name. SE was contrasted with a more severely prosopagnosic patient, PHD, who showed normal ability to recognise buildings and landmarks, indicating that recognition of people dissociates from recognition of buildings/landmarks. It is concluded that SE's failure of place knowledge represents a category specific supramodal semantic memory impairment.

When is a view unusual? A single case study of orientation-dependent visual agnosia

Several hypotheses have been proposed to explain why some neurological patients fail to recognise objects from unusual views: that it results from difficulty identifying an object's principal axis when it is foreshortened, identifying an object when landmark features are occluded, or an inability to rotate mental images. It was possible to test these hypotheses by examining the recognition abilities of a single case (A.S.), by using stimuli that were "unusual" only because of picture-plane misorientation. A.S. showed a recognition deficit in which his accuracy was proportional to the extent of misorientation from the normal upright for the object-although both principal axis and feature information remain visible after picture-plane rotation. Furthermore, A.S. performed with normal accuracy, and normal pattern of reaction time performance, on tasks of mental rotation. These findings suggest that none of these traditional accounts can adequately explain why this patient was unable to recognise objects from unusual views. These findings are discussed the light of recent suggestions of the basis of this type of disorder.

Naming without knowing and appearance without associations: evidence for constructive processes in semantic memory?

This study describes a patient (SE) with temporal lobe injury resulting from Herpes Simplex Encephalitis, who displayed a previously unreported impairment in which his knowledge of associative and functional attributes of animals was disproportionately impaired by comparison with his knowledge of their sensory attributes (including their visual properties and characteristic sounds). His knowledge of man-made objects was preserved. A striking aspect of the present case was that the patient remained able to name many animals from their pictures, despite making gross errors in generating associative information about these same animals. This suggests that a semantic representation incorporating stored sensory knowledge may be sufficient for naming (at least for biological categories) and associative information may be unnecessary. Semantic knowledge may normally incorporate more information than is necessary for identification. SE's errors were found to be confabulatory and reconstructive in nature and it is argued that this aspect of his performance challenges passive conceptions of semantic memory couched in terms of a catalogue of stored representations. It is proposed that the patient's disorder affects a dynamic, constructive, and inferential component of his knowledge base, and that this component is sensitive to semantic category.

Probing sensory and associative semantics for animals and objects in normal subjects

Neuropsychological studies of patients with "category-specific" semantic memory disorders have fuelled a debate concerning the organisation of knowledge. In particular it has been suggested that the reported double dissociation between knowledge of animals and living things on the one hand, and objects on the other, reflects a more fundamental division of semantic representation into functional-associative and sensory-visual domains. The present study attempted to investigate whether there were systematic differences along these dimensions in normal subjects using a sentence-verification technique. It was found that response times were significantly longer for verification of statements concerning the sensory attributes of objects than for statements about their associative attributes. In the case of animals, there were no differences in response latency to associative or sensory statements. In the light of this previously unreported fractionation within verbal semantics, the possible consequences for models of semantic memory are discussed.

Object recognition without knowledge of object orientation

Several theories have been proposed to explain our ability to recognise objects from a number of viewpoints. Orientation-dependent accounts emphasize the position of the object relative to the viewer, while orientation-independent accounts (e.g. Marr) rely on descriptions of an object's component parts relative to its principal axis of elongation. An opportunity to compare the merit of these theories has arisen in a patient (L.G.) who had a rare neuropsychological sign in which knowledge of the canonical upright of object drawings was profoundly disrupted. Such orientation errors were evident in her drawings from memory and to copy, and in an orientation-matching task. In a critical experiment she showed a deficit in providing the canonical upright of individual object drawings that was independent of any difficulty in object recognition. The implications of these data for theories of object recognition are discussed.

Loss of remote memory: a cognitive neuropsychological perspective

Recent, cognitively based neuropsychological studies have established that retrograde amnesia is not a single entity. Profound loss of autobiographical memory, with relative sparing of knowledge of word meaning, facts about other people and personal semantic information, may arise from either disruption of thematic retrieval frameworks or a loss of individual memory traces. The opposite pattern of profound loss of general semantic information with preservation of autobiographical memory also occurs. Finer-grained loss of semantic information, involving famous persons or other categories have also been described, providing important clues regarding the representation and organization of such knowledge.

Multiple meaning systems in the brain: a case for visual semantics

In this study we report our investigations of a category specific visual associative agnosia. The patient D.R.S.'s spoken language skills were excellent. Although he could name objects from their description, he was unable to name them by sight nor was he able to mime their use. On visual-visual matching tasks his performance was impaired and affected by semantic proximity. In two tasks his knowledge of visual objects was demonstrated to be significantly more impaired than his knowledge of visual living things. It is argued that these findings support a multiple knowledge base hypothesis.

Disorders of semantic memory

It is now established that selective disorders of semantic memory may arise after focal cerebral lesions. Debate and dissension remain on three principal issues: category specificity, the status of modality-dependent knowledge, and the stability and sufficiency of stored information. Theories of category specificity have focused on the frequently reported dissociation between living things and man-made objects. However, other dimensions need theoretical integration. Impairments can be both finer-grain and broader in range. A second variable of importance is stimulus modality. Reciprocal interactive dissociations between vision and language and between animals and objects will be described. These indicate that the derivation of semantic information is constrained by input modality: we appear to have evolved separable databases for the visual and the verbal world. Thirdly, an orthogonal distinction has been drawn between degradation disorders, where representations are insufficient for comprehension, and access deficits, in which representations have become unstable. These issues may have their parallel in the acquisition of knowledge by the developing child.

Autobiographical amnesia resulting from bilateral paramedian thalamic infarction. A case study in cognitive neurobiology

A patient with a chronic amnesic state resulting from bilateral paramedian thalamic infarction showed a pattern of retrograde amnesia not previously reported. Personally relevant autobiographical memory was profoundly impaired, whereas knowledge of famous people and public events was relatively spared. Furthermore, knowledge of famous people, including the ability to make accurate temporal judgements, was less affected than knowledge of public events. In addition, we have documented a severe and systematic distortion of personal memory. These findings are not compatible with current accounts of retrograde amnesia based either upon the type of information stored (e.g. episodic versus semantic memory), or upon simple storage versus access models. We propose an explanation based upon an interactive cognitive model in which the patient shows a disorder at the 'thematic retrieval framework' level of memory organization due to a disconnection of frontal and medial temporal memory systems.

Midazolam-induced amnesia: implications for the implicit/explicit memory distinction

In order to examine how the distinction between implicit and explicit memory might relate to theories regarding the organization of memory, two types of memory tests were administered in conjunction with the amnesia-inducing benzodiazepine midazolam. Performance on an implicit task (perceptual facilitation in identifying degraded pictures and words) was relatively unimpaired by midazolam, whereas performance on an explicit task (recognition memory) was severely impaired. Interpreting the results in both the implicit/explicit framework and an independent stage analysis suggests that the terms implicit and explicit may reflect something about the nature of the memory representation and need not be reserved solely to describe classes of memory tasks.

Comparison of the sedative and amnesic effects of midazolam and propofol

We have compared the sedative and amnesic effects of midazolam and propofol in 35 volunteers. Sedation was measured by simple reaction time immediately before and after a bolus injection and 1 h after the commencement of a subsequent continuous infusion. Memory was measured three times using two memory tests: perceptual facilitation provided an implicit memory measure and recognition provided an explicit memory measure. Propofol and midazolam had similar sedative effects both immediately after bolus doses and after 1-h continuous infusions of the drugs. In contrast, midazolam had a more profound amnesic effect than propofol on the recognition memory test. The drugs had little effect on performance with the implicit memory test. Performance on the memory tests was unrelated to sedation.

Actors but not scripts: the dissociation of people and events in retrograde amnesia

We describe our further investigations of the retrograde amnesia in a single case. R.F.R. became globally amnesic following an attack of Herpes Simplex Encephalitis. He could generate and recognize superordinate level information about the vast majority of proper names including the names of people but he was very impaired at giving information about what had "happened" to these same individuals. He could also provide detailed information about family friends but he could not recall salient major personal episodes in which these same individuals had been involved. Knowledge of people appears to be represented in a different way to that of events, even when a singular event has provided the main or only opportunity for learning about the individual.

Collagen I, laminin, and tenascin: ultrastructure and correlation with avian neural crest formation

We have investigated the distribution of type I collagen, tenascin, and laminin in younger chick embryos than have previously been studied in detail. The initial appearance of type I collagen, but not tenascin and laminin, is exactly correlated with the beginning of neural crest migration, suggesting a role for collagen I in the migration. Light microscopy of whole mounts of 2-day-old chick embryos reveals that type I collagen is expressed in a rostral to caudal gradient; it localizes to the notochord sheath before accumulating around the neural tube and somites. Collagen I and tenascin also associate with central somite cells. Surprisingly, no extracellular matrix can be detected among the early sclerotomal cells, which suggests that little or no cell migration is involved in this epithelial-mesenchymal transformation. Electron microscopy using peroxidase antiperoxidase reveals that tenascin is present in nonstriated, 10 nm wide fibrils and in interstitial bodies, both of which have previously been reported to contain fibronectin. However, collagen I only occurs in the 10 nm fibrils and larger striated fibrils. This is the first ultrastructural study to assign tenascin to fibrils and interstitial bodies and to describe its appearance and disappearance from embryonic basement membranes. The discussion emphasizes the possible importance of type I collagen in neural crest cell migration and compares the ultrastructural associations of the ECM molecules present at this early embryonic stage.

Evidence for modality-specific meaning systems in the brain

Patients with cerebral lesions offer a unique opportunity to investigate the organization of meaning systems in the brain. Clinical neurologists have long been aware that knowledge of particular classes or categories of information may be selectively impaired in some cases and selectively spared in others. For example knowledge of letters, colours, objects, or people may be lost as a consequence of damage to the left hemisphere of the brain. Recently there has been quantitative evidence for even more specific impairment and preservation of particular classes of knowledge. More recently the evidence for knowledge of living things as compared with inanimate objects is particularly striking. Such observations have suggested that our semantic knowledge base is categorical in its organization. In this preliminary report, we describe a patient whose semantic knowledge deficit was not only category specific, but also modality specific. Although his knowledge of the visual world was almost entirely normal, his knowledge of living things (but not objects!) was gravely impaired when assessed in the verbal domain. These findings call into question the widely accepted view that the brain has a single all-purpose meaning store.

The fractionation of retrograde amnesia

This single case study describes our investigations of the retrograde memory deficit of a patient who became severely and selectively amnesic after an encephalitic illness. On clinical assessment his retrograde deficit for both personal and public events appeared to encompass his entire adult life. However, he retained knowledge of words introduced into the vocabulary during the retrograde period. The experimental investigation documented his inability to recall, recognize, and place in temporal order the names and faces of famous people for all time periods sampled. By contrast, his recall of either a famous face or a famous name was significantly facilitated by the verbal cue of the person's first name and initial of the surname (i.e., Margaret T...). His performance on a test of "familiarity" that required him to select the famous name or the famous face from two distractors (unknown) was within normal limits. It is argued that names and faces of famous people are represented in more than one system: both in a vocabulary-like fact memory system that is preserved and also in a congnitively mediated schemata that in this case is functionally inoperative.

Understanding: a function of short-term memory?

We describe our investigations of the sentence comprehension abilities of 2 patients with a severe impairment in their auditory verbal short-term memory (conduction aphasia). Both were capable of comprehending a range of sentences, even when adequate comprehension was dependent upon the processing of order-dependent syntactic information rather than the utilization of semantic knowledge. Thus they performed satisfactorily on tests using plausibly reversible subject and object constituents with either active or passive verb phrases or prepositional phrases. Both, however, were impaired on sentences which departed from normal conversational conventions in terms of their reference to the order of event occurrence, or to the subject and object of an array. They were also very poor at performing comparative judgements, even when these involved a simple intrinsic attribute such as colour. These findings are discussed in terms of the role of auditory verbal short-term memory in backing up and back-tracking over spoken information when conditions preclude the immediate understanding of auditory-verbal information.

The double dissociation of short-term memory for lists and sentences. Evidence from aphasia

We document the sentence and list repetition skills of 3 aphasic patients. Cases 1 and 2 were classified as span-impaired conduction aphasics and Case 3 was classified as a span-preserved transcortical sensory aphasic. We found that repetition by the span-impaired cases was facilitated by increasing the 'meaningfulness' of lists, whereas this had no effect on the performance of the span-preserved case. The patients' ability to repeat sentences was contrasted with their ability to repeat three words contained in the sentences, and a double dissociation was obtained: the span-impaired cases were better at repeating sentences than in repeating three word lists whereas the span-preserved case showed the opposite pattern of difficulty. The repetition of sentences containing a known and unknown vocabulary was tested in the span-preserved case. His repetition of sentences containing words which he still knew was significantly better than his ability to repeat sentences containing a vocabulary of words which he had 'forgotten' as a consequence of his aphasia. The patients' ability to repeat complete, incomplete, and nonsense sentences was contrasted: overall the span-impaired patients were somewhat better at repeating complete sentences than incomplete sentences. Finally we examined the patients' ability both to comprehend and repeat word strings in an abbreviated 'naming from description' task: the span-impaired patients were able to comprehend three word strings, but unable to repeat them, the span-preserved case was able to repeat but not comprehend. On the basis of these double dissociations we conclude that the evidence indicates two dissociable short-term memory systems, one a relatively passive phonological store subserving list repetition, the other a dynamic, anticipatory, and integrative memory system which underpins sentence repetition.

Categories of knowledge. Further fractionations and an attempted integration

In this study we investigated the category specificity of the comprehension impairments of Y.O.T., a patient with a severe global dysphasia. Using matching to sample techniques it was possible to demonstrate selective impairments and selective preservations not only of broad categories of semantic knowledge but also of particular subsets of such categories. Specifically, Y.O.T.'s comprehension of 'objects' was, in general, significantly more impaired than for foods or living things. Within the broad class of objects she was significantly more impaired in the comprehension of small manipulable objects than large man-made objects. Within her proper noun vocabulary there was a significant dissociation between her good comprehension of proper nouns having a unique and well-known referent (e.g., Churchill) and common proper nouns without such a referent (e.g., Jones). Her error responses were not consistent, semantic similarity and significant rate effects were observed, and it was therefore considered that her category specific comprehension deficits were primarily ones of access to a full semantic representation. We attempt to give a principled account of the increasing number of seemingly arbitrary instances of fine-grain categorical impairments of semantic knowledge. We have suggested that different weighting values from multiple sensory channels will be important in the acquisition of different categories of knowledge and that such differential weightings could be the basis of the categorical organization of systems in the brain subserving semantic knowledge.

Laminin is structurally conserved in the sea urchin basal lamina

The extracellular matrix is involved in the regulation of differentiation and morphogenesis. Here we report the identification of a sea urchin embryonic extracellular matrix protein by means of a monoclonal antibody BL1 (Mab BL1) and the isolation of the protein from basal lamina preparations. In paraffin sections of fixed embryos, the antibody can be detected on the basal surfaces of cells after the blastula stage. Immunoprecipitation from embryo lysates and salt extracts of metabolically labeled basal lamina preparations demonstrates that the basal lamina antigen is a large mol. wt protein of approximate mol. wt 10 which consists of disulfide-linked subunits of mol. wts 480 000 and 260 000. Electron microscopic images show that the Mab BL1 basal lamina antigen is structurally related to the vertebrate extracellular matrix protein laminin.

Visual associative agnosia: a clinico-anatomical study of a single case

A single case study of a patient with visual associative agnosia is described. The patient had well preserved language, spatial, visual, and perceptual abilities but nevertheless was impaired in recognising visually presented common objects. It is argued that his deficit cannot be accounted for in terms of a disconnection syndrome. Behavioural and anatomical (MRI scan) evidence for focal unilateral dysfunction is presented. It is concluded that the left hemisphere plays a crucial role in recognising the meaning of common objects.

Serum effects on the in vitro differentiation of sea urchin micromeres

When micromeres isolated from the 16-cell stage of Strongylocentrotus purpuratus are cultured in sea water containing 3.5% horse serum, they produce spicules at approximately the same time as in normal development. The serum requirement of the micromeres has been investigated by adding serum at varying intervals after isolation or by pulsing the cells with serum at specific times during their in vitro development. The optimum time of serum addition for spicule formation is 36 h after fertilization (AF). Further delay in the addition of serum results in a reduction in the number of spicules formed in culture and a delay in the time at which they appear. A 1-h pulse of serum at 36 h AF is sufficient to initiate a response in some of the micromere aggregates. A 12-h pulse at 36 h AF produces the maximum number of spicules per culture. The critical period for serum addition, 36-48 h AF, corresponds to the time in the normal embryo at which the syncytial primary mesenchyme ring is formed. Electron micrographs of cultured cells demonstrate that micromeres cultured without serum until 48 h AF fail to form pseudopodial extensions and remain as rosette-like clusters of cells. If serum is present, extensive pseudopodial networks form which resemble the primary ring syncytium. These results suggest that serum acts to stimulate fused pseudopodial networks in cultures of micromeres and that the resulting syncytium is necessary for spicule formation.

The enhancement of reaggregation of sea urchin blastula cells by exogenous proteins

The ability of exogenous proteins to enhance the reaggregation of aggregation-deficient butanol extracted cells has been studied using blastula cells of the sea urchin Arbacia punctulata. Butanol extracts, calcium- and magnesium-free sea-water dissociation supernatant, human plasma fibronectin and bovine serum albumin enhance reaggregation in a concentration dependent manner. Electrophoretic analysis and autoradiography of 125I surface labeled dissociated cells indicate that while butanol extracts a large number of proteins, few iodinated proteins are present in the butanol extract. The non-specificity of proteins to promote reaggregation and the probable cellular location of the butanol extracted proteins are discussed.

Protein composition of the hyaline layer of sea urchin embryos and reaggregating cells

The protein composition of the sea urchin embryo hyaline layer has been studied by 125I surface labeling. The electrophoretic patterns of iodinated proteins indicate that the composition of the hyaline layer is species and stage-specific. Dissociation of iodinated embryos removes some labeled proteins of apparent molecular weights of 290,000, 175,000, 145,000, 110,000, 70,000, and 50,000. The electrophoretic pattern of labeled proteins found in the intact embryo is reestablished on the surface of aggregates following reaggregation. The possible function of these proteins with respect to cell adhesion, cell-sorting behavior and morphogenesis is discussed.

Analysis of sequential letter matching tasks utilising lateralised tachistoscopic presentation

Four experiments are reported in which sequential matches were demanded for double letter stimuli, the first stimulus pair was presented in central vision and the second in the left or right field. The responses were analysed according to the type of classification required (physical or nominal identify, or different). The results indicated that there were alterations in laterality patterns between retention intervals of 50 msec. and 990 msec. despite evidence for a prolonged and stable form of visual memory. These findings were incompatible with a model of the letter matching task which maps "name" codes to the left hemisphere and "visual" codes to the right.

Streptokinase therapy in acute major pulmonary embolism: effectiveness and problems

Eighteen patients with major pulmonary embolism were treated with streptokinase infused by a catheter or given intravenously. Fourteen showed clinical improvement and 12 out of 16 patients investigated showed definite angiographic improvement after 24 to 48 hours of treatment with streptokinase. The angiographic improvement following streptokinase contrasted with the lack of this in three patients after 24 hours of heparin treatment.Resolution following streptokinase therapy was most noticeable in patients treated shortly after a single embolic episode, and was least marked in those with recurrent embolism complicated by associated cardiac or pulmonary disease. Of the four patients who failed to improve, two died and two had pulmonary embolectomy and survived.The results suggest that streptokinase therapy is practicable provided that adequate laboratory control is available, and that it hastens early resolution in acute major pulmonary embolism.