Actinomicosis: dos casos clínicos ginecológicos. No sólo los DIUs tienen la culpa / Actinomycosis: two gynaecological clinical cases. It's not just IUDs to blame

Introducción: La actinomicosis pélvica ha sido descrita en la literatura como asociada al uso de dispositivos intrauterinos, pero no siempre guarda relación con ellos. Hallazgos clínicos: En este artículo describimos dos casos de abscesos pélvicos en dos pacientes con cirugías previas y endometriosis, sin antecedente de uso de DIU. Diagnóstico: En ambas pacientes se aisló Actinomyces turicensis en los cultivos de los abscesos, entre otros microorganismos, siendo diagnosticadas de actinomicosis pélvica. Tratamiento: Las dos pacientes precisaron de drenaje quirúrgico de los abscesos y tratamiento antibiótico durante el ingreso y, una vez que se les dio de alta, requirieron un tratamiento de mantenimiento durante meses con amoxicilina. Resultados: Las dos pacientes mostraron resolución del cuadro clínico, analítico y radiológico durante el seguimiento posterior. Conclusión: Hacemos especial hincapié en la importancia de sospechar y tratar esta infección a tiempo, para evitar cirugías agresivas, así como realizar un adecuado diagnóstico diferencial con otros procesos que pueden presentar síntomas similares.(AU)

Introduction: Pelvic actinomycosis has been described in the literature associated with the use of intrauterine devices, but it is not always related to them. Clinical findings: In this article we describe two cases of pelvic abscesses in two patients with previous surgeries and endometriosis, without a history of IUD use. Diagnosis: Actinomyces turicensis was isolated in both patients in abscess cultures, among other microorganisms, being diagnosed with pelvic actinomycosis. Treatment: The two patients required surgical drainage of the abscesses and antibiotic treatment during admission and once they were discharged, they required maintenance treatment for months with Amoxicillin. Results: Both showed resolution of the clinical, analytical and radiological features during the subsequent follow-up. Conclusion: We place special emphasis on the importance of suspecting and treating this infection in time, to avoid aggressive surgeries and to carry out an adequate differential diagnosis with other processes that can give similar symptoms.(AU)

[The reticular paradigm of cortical memory]. / El paradigma reticular de la memoria cortical.

INTRODUCTION: Recent advances in cognitive neuroscience oblige us to change radically the traditional model of representation of memory in the cerebral cortex. The old -modular- model postulates a separate area for each form of memory (working memory, episodic memory, visual memory, auditory memory, tactile memory, etc.). In the new -reticular- paradigm, memories and items of knowledge are made of widely distributed networks of neuron populations synaptically connected by experience. DEVELOPMENT: Memory networks overlap and interact profusely; a neuron or group of neurons can be part of many networks, thus many memories or items of knowledge. After birth and throughout life, each new experience is etched in the form of those networks or cognits by synaptic associative processes that course from area to area along phylogenetic, ontogenetic, and connective gradients, from sensory and motor areas into associative areas. By self-organization, new cognits distribute themselves within two cortical hierarchies with a sensory and motor base, respectively. The perceptual hierarchy, in posterior cortex, houses cognits defined by sensory parameters in sensory areas and perceptual memories in associative areas. The executive hierarchy, on the other hand, represents concrete movements in frontal motor areas and more complex actions (e.g., plans) in prefrontal cortex. CONCLUSIONS: The reticular memory paradigm has important implications with regard to the cognitive development of the individual, cortical clinical syndromes, and cognitive rehabilitation.

Patterned firing of parietal cells in a haptic working memory task.

Abstract Cells in the somatosensory cortex of the monkey are known to exhibit sustained elevations of firing frequency during the short-term mnemonic retention of tactile information in a haptic delay task. In this study, we examine the possibility that those firing elevations are accompanied by changes in firing pattern. Patterns are identified by the application of a pattern-searching algorithm to the interspike intervals of spike trains. By sequential use of sets of pattern templates with a range of temporal resolutions, we find patterned activity in the majority of the cells investigated. In general, the degree of patterning significantly increases during active memory. Surrogate analysis suggests that the observed patterns may not be simple linear stochastic functions of instantaneous or average firing frequency. Therefore, during the active retention of a memorandum, the activity of a 'memory cell' may be characterized not only by changes in frequency but also by changes in pattern.

The brain decade in debate: I. Neurobiology of learning and memory.

This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed.

The brain decade in debate: I. Neurobiology of learning and memory

This article is a transcription of an electronic symposium in which some active researchers were invited by the Brazilian Society for Neuroscience and Behavior (SBNeC) to discuss the last decade's advances in neurobiology of learning and memory. The way different parts of the brain are recruited during the storage of different kinds of memory (e.g., short-term vs long-term memory, declarative vs procedural memory) and even the property of these divisions were discussed. It was pointed out that the brain does not really store memories, but stores traces of information that are later used to create memories, not always expressing a completely veridical picture of the past experienced reality. To perform this process different parts of the brain act as important nodes of the neural network that encode, store and retrieve the information that will be used to create memories. Some of the brain regions are recognizably active during the activation of short-term working memory (e.g., prefrontal cortex), or the storage of information retrieved as long-term explicit memories (e.g., hippocampus and related cortical areas) or the modulation of the storage of memories related to emotional events (e.g., amygdala). This does not mean that there is a separate neural structure completely supporting the storage of each kind of memory but means that these memories critically depend on the functioning of these neural structures. The current view is that there is no sense in talking about hippocampus-based or amygdala-based memory since this implies that there is a one-to-one correspondence. The present question to be solved is how systems interact in memory. The pertinence of attributing a critical role to cellular processes like synaptic tagging and protein kinase A activation to explain the memory storage processes at the cellular level was also discussed

Prefrontal neurons in networks of executive memory.

The neuronal networks of the frontal lobe that represent motor or executive memories are probably the same networks that cooperate with other cerebral structures in the temporal organization of behavior. The prefrontal cortex, at the top of the perception-action cycle, plays a critical role in the mediation of contingencies of action across time, an essential aspect of temporal organization. That role of cross-temporal mediation is based on the interplay of two short-term cognitive functions: one retrospective, of short-term active perceptual memory, and the other prospective, of attentive set (or active motor memory). Both appear represented in the neuronal populations of dorsolateral prefrontal cortex. At least one of the mechanisms for the retention of active memory of either kind seems to be the reentry of excitability through recurrent cortical circuits. With those two complementary and temporally symmetrical cognitive functions of active memory for the sensory past and for the motor future, the prefrontal cortex seems to secure the temporal closure at the top of the perception-action cycle.

Executive frontal functions.

This chapter presents a conceptual model of the representational and executive functions of the cortex of the frontal lobe derived from empirical evidence obtained principally in the monkey. According to this model, the neuronal networks of the frontal lobe that represent motor or executive memories are probably the same networks that cooperate with other cerebral structures in the temporal organization of behavior. The prefrontal cortex, at the top of the perception-action cycle, plays a critical role in the mediation of contingencies of action across time, an essential aspect of the temporal organization of behavior. That role of cross-temporal mediation is based on the interplay of two short-term cognitive functions: one retrospective, of short-term memory or sensory working memory, and the other prospective, of attentive set (or motor working memory). Both appear represented in the neuronal populations of dorsolateral prefrontal cortex. At least one of the mechanisms for the retention of working memory of either kind seems to be the reentry of excitability through recurrent cortical circuits. With those two complementary and temporally symmetrical cognitive functions of active memory for the sensory past and for the motor future, the prefrontal cortex secures the temporal closure at the top of the perception-action cycle.

Visuo-tactile cross-modal associations in cortical somatosensory cells.

Recent studies show that cells in the somatosensory cortex are involved in the short-term retention of tactile information. In addition, some somatosensory cells appear to retain visual information that has been associated with the touch of an object. The presence of such cells suggests that nontactile stimuli associated with touch have access to cortical neuron networks engaged in the haptic sense. Thus, we inferred that somatosensory cells would respond to behaviorally associated visual and tactile stimuli. To test this assumption, single units were recorded from the anterior parietal cortex (Brodmann's areas 3a, 3b, 1, and 2) of monkeys performing a visuo-haptic delay task, which required the memorization of a visual cue for a tactile choice. Most cells responding to that cue responded also to the corresponding object presented for tactile choice. Significant correlations were observed in some cells between their differential reactions to tactile objects and their differential reactions to the associated visual cues. Some cells were recorded in both the cross-modal task and a haptic unimodal task, where the animal had to retain a tactile cue for a tactile choice. In most of these cells, correlations were observed between stimulus-related firing in corresponding cue periods of the two tasks. These findings suggest that cells in somatosensory cortex are the components of neuronal networks representing tactile information. Associated visual stimuli may activate such networks through visuo-haptic associations established by behavioral training.

Cross-modal and cross-temporal association in neurons of frontal cortex.

The prefrontal cortex is essential for the temporal integration of sensory information in behavioural and linguistic sequences. Such information is commonly encoded in more than one sense modality, notably sight and sound. Connections from sensory cortices to the prefrontal cortex support its integrative function. Here we present the first evidence that prefrontal cortex cells associate visual and auditory stimuli across time. We gave monkeys the task of remembering a tone of a certain pitch for 10 s and then choosing the colour associated with it. In this task, prefrontal cortex cells responded selectively to tones, and most of them also responded to colours according to the task rule. Thus, their reaction to a tone was correlated with their subsequent reaction to the associated colour. This correlation faltered in trials ending in behavioural error. We conclude that prefrontal cortex neurons are part of integrative networks that represent behaviourally meaningful cross-modal associations. The orderly and timely activation of neurons in such networks is crucial for the temporal transfer of information in the structuring of behaviour, reasoning and language.

Intracardiac thrombosis in a case of Behcet's disease associated with the prothrombin 20210G-A mutation.

Thrombosis occurs in 20 to 30% of patients with Behçet's disease (BD), but the precise pathogenic mechanism underlying the thrombotic tendency in these patients is not well known. Venous thromboses are commonly located in the lower extremities, but right intracardiac thrombi are extremely rare. We report for the first time on a young patient with BD associated the 20210G-A prothrombin gene mutation and right intracardiac thrombosis. We suggest that the association of BD with this newly recognized prothrombotic genetic mutation may have contributed to the development of the thrombotic event in this patient.

Cortical dynamics of memory.

Memory networks are formed in the cerebral cortex by associative processes, following Hebbian principles of synaptic modulation. Sensory and motor memory networks are made of elementary representations in cell assemblies of primary sensory and motor cortex (phyletic memory). Higher-order individual memories, e.g. episodic, semantic, conceptual - are represented in hierarchically organized neuronal networks of the cortex of association. Perceptual memories are organized in posterior (post-rolandic) cortex, motor (executive) memories in cortex of the frontal lobe. Memory networks overlap and interact profusely with one another, such that a cellular assembly can be part of many memories or networks. Working memory essentially consists in the temporary activation of a memory network, as needed for the execution of successive acts in a temporal structure of behavior. That activation of the network is maintained by recurrent excitation through reentrant circuits. The recurrent reentry may occur within local circuits as well as between separate cortical areas. In either case. recurrence binds together the associated components of the network and thus of the memory it represents.

From perception to action: temporal integrative functions of prefrontal and parietal neurons.

The dorsolateral prefrontal cortex (DPFC) and the posterior parietal cortex (PPC) are anatomically and functionally interconnected, and have been implicated in working memory and the preparation for behavioral action. To substantiate those functions at the neuronal level, we designed a visuomotor task that dissociated the perceptual and executive aspects of the perception-action cycle in both space and time. In that task, the trial-initiating cue (a color) indicated with different degrees of certainty the direction of the correct manual response 12 s later. We recorded extracellular activity from 258 prefrontal and 223 parietal units in two monkeys performing the task. In the DPFC, some units (memory cells) were attuned to the color of the cue, independent of the response-direction it connoted. Their discharge tended to diminish in the course of the delay between cue and response. In contrast, few color-related units were found in PPC, and these did not show decreasing patterns of delay activity. Other units in both cortices (set cells) were attuned to response-direction and tended to accelerate their firing in anticipation of the response and in proportion to the predictability of its direction. A third group of units was related to the determinacy of the act; their firing was attuned to the certainty with which the animal could predict the correct response, whatever its direction. Cells of the three types were found closely intermingled histologically. These findings further support and define the role of DPFC in executive functions and in the temporal closure of the perception-action cycle. The findings also agree with the involvement of PPC in spatial aspects of visuomotor behavior, and add a temporal integrative dimension to that involvement. Together, the results provide physiological evidence for the role of a prefrontal-parietal network in the integration of perception with action across time.

Synopsis of function and dysfunction of the frontal lobe.

The cortex of the frontal lobe reaches maximum phylogenetic development in the brain of the human. It is cortex devoted to the organization of action in all neurobiological and cognitive domains - skeletal movement, eye movement, speech and logical reasoning. Thus the frontal cortex may be called 'motor cortex' in the widest sense. The association cortex of the frontal lobe, commonly called prefrontal cortex, is in charge of the temporal organization of behaviour, speech and thinking. Prefrontal lesions frequently lead to disorders of temporal organization, especially in thinking and the spoken language. The prefrontal cortex serves temporal organization by coordinating three cognitive operations that are essential for the formation of 'gestalts' in the time domain: (i) preparatory set; (ii) working memory; and (iii) inhibitory control of interference. Temporal organization is disturbed in the schizophrenic patient, probably because of a functional disorder of the connectivity between the prefrontal cortex and other cortical areas, as well as limbic and striatal structures (a 'disconnection syndrome').

Cellular dynamics of network memory.

One example of "emergence" is the development, as a result of neural ontogeny and living experience, of cortical networks capable of representing and retaining cognitive information. A large body of evidence from neuropsychology, electrophysiology and neuroimaging indicates that so-called working memory and long-term memory share the same neural substrate in the cerebral cortex. That substrate consists in a system of widespread, overlapping and hierarchically organized networks of cortical neurons. In this system, any neuron or group of neurons can be part of many networks, and thus many memories. Working memory is the temporary activation of one such network of long-term memory for the purpose of executing an action in the near future. The activation of the network may be brought about by stimuli that by virtue of prior experience are in some manner associated with the cognitive content of the network, including the response of the organism to those stimuli. The mechanisms by which the network stays activated are presumed to include the recurrent re-entry of impulses through associated neuronal assemblies of the network. Consistent with this notion is the following evidence: (1) working memory depends on the functional integrity of cortico-cortical connective loops; and (2) during working memory, remarkable similarities--including "attractor behavior"--have been observed between firing patterns in real cortex and in an artificial recurrent network.

Distributed memory for both short and long term.

Neuropsychology points to the wide distribution of cortical memory networks. Electrophysiology and neuroimaging indicate that working memory, like long-term memory, is a widely distributed function, largely neocortical. Most of the evidence available from those three methodologies suggests that both working memory and long-term memory share the same substrate: a system of broad, partly overlapping and interconnected neocortical networks. Working memory appears mostly, if not completely, characterized by the sustained activation of one widely distributed network of long-term memory. That activation is at least in part sustained by reentrant excitatory loops through the different neuronal assemblies that constitute the network and that represent the associated features of the memorandum.

High-frequency transitions in cortical spike trains related to short-term memory.

Single-unit spike trains recorded from parietal cortex of monkeys performing a tactile short-term memory task show characteristic fluctuations (transitions) in their firing frequency that are related to memory. Spike trains recorded during the memory period, when the animal must retain information for the short term, show a higher rate of such transitions than spike trains recorded during intertrial baseline periods. In the present study, an analysis of multiple temporal resolutions over which these transitions are observed reveals that the memory-related transitions occur most prominently in the 25-50 Hz range. The results of this study suggest that, in the monkey, high frequency fluctuations of neuronal discharge in the parietal cortex are correlated with haptic short-term memory. The presence of such fluctuations are also consistent with theoretical models of short-term memory.