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This paper is concerned with a striking visual experience: that of seeing geometric visual hallucinations. Hallucinatory images were classified by Klüver into four groups called form constants comprising (i) gratings, lattices, fretworks, filigrees, honeycombs and chequer-boards, (ii) cobwebs, (iii) tunnels, funnels, alleys, cones and vessels, and (iv) spirals. This paper describes a mathematical investigation of their origin based on the assumption that the patterns of connection between retina and striate cortex (henceforth referred to as V1)-the retinocortical map-and of neuronal circuits in V1, both local and lateral, determine their geometry. In the first part of the paper we show that form constants, when viewed in V1 coordinates, essentially correspond to combinations of plane waves, the wavelengths of which are integral multiples of the width of a human Hubel-Wiesel hypercolumn, ca. 1.33-2 mm. We next introduce a mathematical description of the large-scale dynamics of V1 in terms of the continuum limit of a lattice of interconnected hypercolumns, each of which itself comprises a number of interconnected iso-orientation columns. We then show that the patterns of interconnection in V1 exhibit a very interesting symmetry, i.e. they are invariant under the action of the planar Euclidean group E(2)-the group of rigid motions in the plane-rotations, reflections and translations. What is novel is that the lateral connectivity of V1 is such that a new group action is needed to represent its properties: by virtue of its anisotropy it is invariant with respect to certain shifts and twists of the plane. It is this shift-twist invariance that generates new representations of E(2). Assuming that the strength of lateral connections is weak compared with that of local connections, we next calculate the eigenvalues and eigenfunctions of the cortical dynamics, using Rayleigh-Schrödinger perturbation theory. The result is that in the absence of lateral connections, the eigenfunctions are degenerate, comprising both even and odd combinations of sinusoids in straight phi, the cortical label for orientation preference, and plane waves in r, the cortical position coordinate. 'Switching-on' the lateral interactions breaks the degeneracy and either even or else odd eigenfunctions are selected. These results can be shown to follow directly from the Euclidean symmetry we have imposed. In the second part of the paper we study the nature of various even and odd combinations of eigenfunctions or planforms, the symmetries of which are such that they remain invariant under the particular action of E(2) we have imposed. These symmetries correspond to certain subgroups of E(2), the so-called axial subgroups. Axial subgroups are important in that the equivariant branching lemma indicates that when a symmetrical dynamical system becomes unstable, new solutions emerge which have symmetries corresponding to the axial subgroups of the underlying symmetry group. This is precisely the case studied in this paper. Thus we study the various planforms that emerge when our model V1 dynamics become unstable under the presumed action of hallucinogens or flickering lights. We show that the planforms correspond to the axial subgroups of E(2), under the shift-twist action. We then compute what such planforms would look like in the visual field, given an extension of the retinocortical map to include its action on local edges and contours. What is most interesting is that, given our interpretation of the correspondence between V1 planforms and perceived patterns, the set of planforms generates representatives of all the form constants. It is also noteworthy that the planforms derived from our continuum model naturally divide V1 into what are called linear regions, in which the pattern has a near constant orientation, reminiscent of the iso-orientation patches constructed via optical imaging. The boundaries of such regions form fractures whose points of intersection correspond to the well-known 'pinwheels'. To complete the study we then investigate the stability of the planforms, using methods of nonlinear stability analysis, including Liapunov-Schmidt reduction and Poincaré-Lindstedt perturbation theory. We find a close correspondence between stable planforms and form constants. The results are sensitive to the detailed specification of the lateral connectivity and suggest an interesting possibility, that the cortical mechanisms by which geometric visual hallucinations are generated, if sited mainly in V1, are closely related to those involved in the processing of edges and contours.

Most terminally ill patients experience symptoms that require treatment as death approaches. The most common symptoms are pain (5% to 51%), dyspnea (28%), oral and respiratory secretions (25%), nausea and vomiting (10% to 14%), confusion (10%), myoclonus (12%), and bowel and bladder problems (over 20%). These symptoms can be well controlled in up to 90% of individuals with appropriate communication; emotional, spiritual, and social support; noninvasive clinical evaluation; and therapy focused on symptom palliation. Types of drugs that are important in symptom control include opioids, co-analgesics, anxiolytics, and anticholinergics. To be effective, these medications must be readily available for use and often need to be given by a non-oral route.

We propose a model for the lateral connectivity of orientation-selective cells in the visual cortex. We study the properties of the input signal to the visual cortex and find new statistical structures that have not been processed in the retino-geniculate pathway. Using the idea that the system performs redundancy reduction of the incoming signals, we derive the lateral connectivity that will achieve this for a set of orientation-selective local circuits, as well as the complete spatial structure of a network composed of such circuits. We compare the results with various physiological measurements.

The spike timing reliability of Aplysia motoneurons stimulated by repeated presentation of periodic or aperiodic input currents is investigated. Two properties of the input are varied, the frequency content and the relative amplitude of the fluctuations to the mean (expressed as the coefficient of variation: CV). It is shown that, for small relative amplitude fluctuations (CV approximately 0.05-0.15), the reliability of spike timing is enhanced if the input contains a resonant frequency equal to the firing rate of the neuron in response to the DC component of the input. This resonance-related enhancement in reliability decreases as the relative amplitude of the fluctuations increases (CV-->1). Similar results were obtained for a leaky integrate-and-fire neuronal model, suggesting that these effects are a general property of encoders that combine a threshold with a leaky integrator. These observations suggest that, when the magnitude of input fluctuations is small, changes in the power spectrum of the current fluctuations or in the spike discharge rate can have a pronounced effect on the ability of the neuron to encode a time-varying input with reliably timed spikes.

Exploiting local stability, we show what neuronal characteristics are essential to ensure that coherent oscillations are asymptotically stable in a spatially homogeneous network of spiking neurons. Under standard conditions, a necessary and, in the limit of a large number of interacting neighbors, also sufficient condition is that the postsynaptic potential is increasing in time as the neurons fire. If the postsynaptic potential is decreasing, oscillations are bound to be unstable. This is a kind of locking theorem and boils down to a subtle interplay of axonal delays, postsynaptic potentials, and refractory behavior. The theorem also allows for mixtures of excitatory and inhibitory interactions. On the basis of the locking theorem, we present a simple geometric method to verify the existence and local stability of a coherent oscillation.

Visually evoked potentials (VEPs) were recorded during simple motor reaction time (RT) experiments using spatially localized, contrast modulated visual stimuli. VEPs were averaged in groups, called "subensembles," depending on the speed of the subject's motor response. To a specific visual stimulus, the VEP response time of a subensemble covaries with motor response latency according to the same linear relationship found to describe conventionally averaged VEPs and RTs over a wide range of stimuli.

Spatially localized, contrast modulated visual stimuli evoke a monophasic, inion negative scalp potential (VEP) which can be recorded simultaneously with motor responses in simple reaction time experiments. VEP response time and median motor response latency are linearly related over a wide range of stimuli. We interpret our results to suggest that VEPs and motor response latencies arise from a common sensory system with different thresholds for detection and reaction. A model is introduced to predict detection thresholds from VEP response times which are usually more robust measures than VEP amplitudes.

Four hundred eleven women with metastatic breast cancer were randomly assigned to receive either 60 mg/m2 doxorubicin (130 patients), 320 mg/m2 bisantrene (146 patients), or 14 mg/m2 mitoxantrone (135 patients). The doses were given intravenously every 3 weeks with a cross-over design to determine their relative efficacy and toxicity. To be eligible, patients must have had one previous chemotherapy regimen, and patients who were estrogen receptor positive must have failed endocrine therapy. There were 365 patients assessable for response and 399 assessable for toxic effects. The median age was 57 years; 18% were premenopausal or perimenopausal. Visceral dominant disease was present in 66% of the patients. Ninety-seven percent of the patients had a disease-free interval from diagnosis to first recurrence of less than 1 year. The response rate was 28% with doxorubicin, 13% with bisantrene, and 14% with mitoxantrone (P = .004). Median time to treatment failure was 133 days with doxorubicin, 66 days with bisantrene, and 68 days with mitoxantrone (logrank P = .06). The median survival was 315 days for doxorubicin, 290 days for bisantrene, and 177 days for mitoxantrone (logrank P = .04), although survival at 2 years was similar for all three agents. There were five responses in the 66 patients crossed over to doxorubicin and one response each for patients crossed over to bisantrene (39 patients) or mitoxantrone (63 patients). Toxicity leading to discontinuance of therapy was more common with doxorubicin, and discontinuance of therapy was due primarily to patient's request or cardiotoxicity. The major dose-limiting toxic effect for all three agents was leukopenia. Nausea and vomiting, mucositis, and alopecia were more severe with doxorubicin. Congestive heart failure developed in nine patients treated with doxorubicin, zero patients treated with bisantrene, and two patients treated with mitoxantrone. A decrease in the left ventricular ejection fraction, as defined by moderate to severe Alexander grade changes, was more common in patients treated with doxorubicin (doxorubicin-treated patients = 20%, bisantrene-treated patients = 5%, and mitoxantrone-treated patients = 10%). This study demonstrates that bisantrene and mitoxantrone have only modest activity in metastatic breast carcinoma. The activity of doxorubicin is greater than that of the other two agents, but at a cost of increased toxicity.

The human tumor cloning assay as described by Hamburger and Salmon was utilized to study the direct antitumor effects of the hypoxic cell sensitizer misonidazole (MISO). Cells from 106 tumor specimens directly obtained from patients were exposed to MISO at clinically achievable drug concentrations (0.5 mM). Of 30 evaluable tumors, seven specimens (23%) showed a less than or equal to 50% decrease of TCFU's. In vitro sensitivity to MISO was noted in human breast cancer, renal cancer, non small-cell lung cancer, and adenocarcinoma of unknown primary site. A dose response relationship was demonstrated in a subset of experiments including 6 patient's tumors and one human breast cancer cell-line. An analysis relating MISO sensitivity or resistance to the results obtained with other, simultaneously tested standard anticancer drugs indicated that tumors exhibiting a less than or equal to 50% decrease of TCFU's in the presence of MISO were also likely to be sensitive to other cytotoxic drugs. In summary, our data suggest that the 'nitroimidazoles' may exert clinically significant direct antitumor effects in individual tumors. The human tumor cloning assay may have potential to evaluate these direct effects of MISO-analogues and other new radiosensitizers currently being tested in clinical trials.

Specimens (173) were evaluated to assess the predictive value of cell viability as measured by Trypan Blue exclusion on colony formation in a human tumor cloning system. Overall, there was no significant correlation between Trypan Blue exclusion-determined viability and colony formation in soft agar for these specimens (p = 0.43). This lack of significant correlation was maintained for primary, metastatic, solid, and fluid tumor specimens. These data suggest that, in this soft agar system, specimens containing cells with low Trypan Blue exclusion viability should not be excluded from testing, and that it may not be advantageous to plate on the basis of "viable cells" as measured by Trypan Blue exclusion.

A computational model is presented which simulates the development and regeneration of orderly connections between retinal fibers and tectal cells in frogs and goldfish. The model distinguishes two aspects of retinotectal connectivity: (1) the contact adhesion between retinal fibers and tectal cells as mediated by fixed chemospecific markers and (2) the formation of modifiable synapses between them. Chemospecificity is assumed to be an intrinsic property of both the retina and tectum and is modeled as a graded distribution of a binding determinant or marker. Synapse formation depends upon the timing of neural activity as well as on the intinsic chemospecificity of retinotectal contacts. In addition to the normal development and regeneration of the retinotectal map, the model simulates the compressed, expanded, translocated, and rotated maps that have been found in surgically manipulated contexts. There examples of plasticity in the retinotectal map can be simulated without assuming any changes in the marker distributions. Moreover, the model demonstrates that a very shallow gradient of a single marker suffices to organize retinotectal connections in a variety of contexts.

A simple graphical calculus is developed that generates analytic solutions for membrane potential transforms at any point on the dendritic tree of neurons with arbitrary dendritic geometries, in response to synaptic "current" inputs. Such solutions permit the computation of transients in neurons with arbitrary geometry and may facilitate analysis of the role of dendrites in such cells.

Several hypotheses suggest that alcohol is often used to "escape"--to forget unpleasant feelings resulting from personal problems or social stresses. To test alcohol's effects on memory for feelings, 1.1 ml/kg of alcohol (A) or placebo (P) was given in two sessions, 48 hours apart, to 32 subjects divided into four equal drug groups (P-P, P-A, A-P, A-A). The subjects filled out the Profile on Mood States (POMS) after drug ingestion in session 1 while experiencing and learning these emotions. Their memories were tested when they tried to replicate these POMS ratings after drug ingestion in session 2. Alcohol given before memory testing decreased accuracy on each of the six POMS scales, especially Fatigue. However, alcohol did not impair memory for previously learned verbal and pictorial stimuli, and it produced no measurable changes in current feelings. These findings indicate that the impairment of memory for feelings may be a newly discovered specific pharmacological effect of alcohol.

Serious complications occurred in 29 of 887 children with puncture wounds of the feet treated over a four-year period at the Dr. Charles A. Janeway Child Health Centre. Osteomyelitis in one of the small bones of the foot was the commonest complication and occurred when a cartilaginous surface (physeal plate or articular cartilage) had been violated. Although systemic signs of osteomyelitis frequently are absent, this infectious process is refractory to medical management. The combined surgical and medical management of this complication is outlined. Management of puncture wounds in the emergency room should include a thorough history concisely recorded, tetanus prophylaxis, and cleansing, debridement, and probing of the wound. Antimicrobial agents are not routinely required but should be reserved for patients presenting late with cellulitis or an established infection. A semisynthetic penicillinase-penicillin appears to be the agent of choice until the results of microbiologic studies are available.

Patients with a pathologically proven diagnosis of malignant melanoma were entered into a phase II trial of bisantrene. Eligibility criteria included: measurable, metastatic disease; performance status 0-2 SWOG; and adriamycin total cumulative dose of less than 400 mg/m2. The initial bisantrene dosing schedule was 260 mg/m2 every three weeks for good risk patients. Due to the absence of an objective response and the lack of severe toxicity in the first 25 bisantrene treated patients, the starting dose was increased to 300 mg/m2 for good risk patients. Fifty-one patients received a median of two bisantrene courses (range 1-11 courses). Leukopenia was the major toxicity. Fifteen (68%) of the 22 good risk, intermediate dose patients (260 mg/m2), and 8 (80%) of the 10 good risk, high dose patients (300 mg/m2) evaluable for toxicity experienced mild-severe leukopenia. None of the 51 patients experienced a complete or partial response to bisantrene. Median survival was 3.3 months. We conclude that bisantrene is ineffective in the treatment of metastatic melanoma.

New agents with increased activity and/or reduced toxicity are needed for the treatment of advanced breast cancer. The anthracene derivatives mitoxantrone and bisantrene had significant activity and acceptable toxicity in phase II trials. In an ongoing phase III trial we have now randomized 150 patients with advanced breast cancer to either doxorubicin (60 mg/m2), mitoxantrone (14 mg/m2) or bisantrene (260 mg/m2) i.v. q 3 weeks with re-randomization for cross-over at the time of progression to determine the relative efficacy and toxicity of these three agents. To be eligible, patients must have had only one previous chemotherapy regimen. ER positive patients must have failed endocrine therapy. Patients with CHF or severe cardiac disease were ineligible. In this preliminary evaluation, 117 patients are evaluable for response and 110 for toxicity. Median age for all patients is 58 years (range 26-78). The majority (86%) are postmenopausal. Fifty-nine percent percent of the patients have visceral dominant disease. Estrogen receptor is positive in 37%, negative in 39% and unknown in 24% of patients. Median performance status (SWOG) is 1, range 0-2. Objective responses have been observed on each arm (doxorubicin 9/35, mitoxantrone 6/38, bisantrene 6/44). Thirty-two patients are evaluable for cross-over response (doxorubicin 2/13, mitoxantrone 1/11, bisantrene 0/8). The predominant toxicity is leukopenia with a nadir WBC count less than 2000 in 45% of all courses administered. Leukopenia is similar with the three drugs. Significant nausea, vomiting and alopecia are common with doxorubicin and uncommon with the other agents. Congestive heart failure has been observed in one patient (doxorubicin). Definitive conclusions regarding the efficacy and toxicity of these agents await the completion of this trial.

We performed serial histories, physical examinations, and nerve conduction studies on seven cancer patients who were treated with cis-diamminedichloroplatinum(II). Total cumulative doses ranged from 200 to 350 mg/m2. In nerve conduction studies, three of seven patients showed subclinical, predominantly sensory, changes compatible with a peripheral neuropathy.