Parotid hypersalivation after inferior salivatory nucleus glutamate/NMDA receptor excitation in the rat.

Although salivation is essential during eating behavior, little is known about the brainstem centers that directly control the salivary glands. With regard to the inferior salivatory nucleus (ISN), the site of origin of the parasympathetic preganglionic cell bodies that innervate the parotid glands, previous anatomical studies have located it within the rostrodorsal medullary reticular formation. However, to date there is no functional data that shows the secretory nature of the somas grouped in this region. To activate only the somas and rule out the activation of the efferent fibers from and the afferent fibers to the ISN, in exp. 1, NMDA neurotoxin was administered to the rostrodorsal medullary region and the secretion of saliva was recorded during the following hour. Results showed an increased secretion of parotid saliva but a total absence of submandibular-sublingual secretion. In exp. 2, results showed that the hypersecretion of parotid saliva after NMDA microinjection was completely blocked by the administration of atropine (a cholinergic blocker) but not after administration of dihydroergotamine plus propranolol (α and ß-adrenergic blockers, respectively). These findings suggest that the somata of the rostrodorsal medulla are secretory in nature, controlling parotid secretion via a cholinergic pathway. The data thus functionally supports the idea that these cells constitute the ISN.

Microinjection of NMDA-neurotoxin into the superior salivatory nucleus of the rat: Short-term secretory and long-term drinking behavior effects.

The anatomical location of the superior salivatory nucleus (SSN), the site of origin of the parasympathetic preganglionic cell bodies that innervate the submandibular-sublingual salivary glands, is well established in rats. However, as of yet there is no functional data that convincingly shows the secretory nature of this region. Previous studies have not been able to differentiate between interventions on efferent or afferent fibers connected to the SSN versus interventions on the salivatory nucleus itself. Taking advantage of the fact that salivatory neurons express NMDA-receptors on their somas, in the present study SSN cell bodies were activated and lesioned sequentially by means of intracerebral application of NMDA-neurotoxin. In exp. 1 two effects, a short- and a long-term effect, were observed following NMDA administration. The first effect was high submandibular-sublingual saliva secretion during the hour following administration of the neurotoxin and the second was a profound change in drinking behavior once the animals recovered from the lesion. Thus, on post-surgery days 16, 17 and 18, the rats exhibited hyperdipsia in the presence of dry food but not in the presence of wet food. In expt. 2 results showed that saliva hypersecretion observed after NMDA-microinjection was completely blocked by the administration of atropine (a cholinergic blocker) but not after the administration of dihydroergotamine plus propranolol (α and ß-adrenergic blockers, respectively). From a functional perspective, these data suggest that the somata of the parvocellular reticular formation control the secretory activity of the submandibular-sublingual salivary glands and thus constitute the SSN.

Do device that simulate methane capture equipment, as a mask located in the head of dairy cows affect their welfare?

The objective of this study was to determine if device that simulate methane capture equipment (DSMC) located in the frontal part of the head of dairy cows affect animal welfare using productive, behavioral, biochemical and physiological indicators. Twenty Holstein dairy cows were assigned to one of the two following treatments: cows with DSMC (CDSMC, n=10) and cows without methane capture devices (CC, n=10). Treatment did not affect neither milk production nor biochemical blood. The group CDSMC tended to ruminate less (P=0.06) and tended to eat more (P=0.08) frequently than the group CC. In conclusion, considering the data set, the welfare of the cows was not significantly affected by the use of DSMC located in their heads.

Rapid decay of spatial memory acquired in rats with ventral hippocampus lesions.

Several memory consolidation theories have proposed that following a learning situation the hippocampus gradually stabilizes labile recent memories into long-lasting remote memories. Most work in this field has focused on the dorsal hippocampus (DHip), giving little consideration to a possible contribution by the ventral hippocampus (VHip), particularly when spatial paradigms are used. However, in recent years a growing number of studies have suggested the existence of a functional continuum, related to spatial processing and navigation, along the dorsoventral hippocampal axis. For this reason, in the present study we compare the effect of DHip vs. VHip lesions on long-term spatial memory retention. Using a four-arm plus-shaped maze, rats with lesions in the DHip, VHip or sham-lesioned learned to criterion a place discrimination task based on allothetic cues. During two retraining phases (2 days and 24 days after learning) retention of the spatial information learned during the acquisition phase was evaluated. The main findings revealed no deficit 2 days after learning, but 24 days after learning both lesioned groups showed a profound impairment compared to control animals (expt. 1). In contrast, when rats learned a cue-guided navigation task in the acquisition phase, both lesioned groups performed the two retention tests, 2 days and 24 days after learning, at the same level as the control group (expt. 2). These results suggest not only that the DHip is vital, but also that normal VHip activity is critical during the post-learning period in order for a recent spatial memory to become a stable long-term memory.

Ventral hippocampus lesions and allocentric spatial memory in the radial maze: Anterograde and retrograde deficits.

Although the dorsal hippocampus (DHip) has been clearly implicated in spatial learning and memory, there is currently debate as to whether the ventral hippocampus (VHip) is also necessary in allocentric-based navigation tasks. To differentiate between these two subregions of the hippocampal dorsoventral axis, we examined the effect of neurotoxic lesions to the DHip and VHip in different learning situations, using a four-arm plus-shaped maze. In experiment 1 a spatial reference memory task was used, with results showing an acquisition deficit in DHip-lesioned rats but perfect learning in VHip-lesioned rats. However, in experiment 2 an acquisition deficit was found in VHip-lesioned rats using a doubly marked training protocol. In this case the position of the goal arm during training was marked simultaneously by the extramaze constellation of stimuli around the maze and an intramaze cue. The main results indicated that DHip and VHip groups presented significantly more allocentric errors in the probe test than the control rats. In experiments 3 and 4, animals with their brains still intact learned, respectively, a spatial reference memory task or a purely cue-guided navigation task, and DHip and VHip lesions were made 2-3 days after reaching learning criterion. Results indicated a profound retrograde deficit in both lesioned groups but only with regard to allocentric information. So, depending on the training protocol used, our results point to increased integration and cooperation throughout the hippocampal dorsoventral axis when allocentric learning and memory is involved. These data support the existence of a functional continuum from the dorsal to the ventral hippocampus.

Disconnection of the perirhinal and insular cortices severely disrupts taste neophobia.

It is well known that the perirhinal (Prh) and insular (IC) cortices are reciprocally connected, mainly through ipsilateral projections. Although some studies have demonstrated that excitotoxic lesions to these regions, each separately, disrupt taste neophobia, it is not yet known whether the two regions have functional interactions with one another. To find out if they form a functional unit, we examined the effects of crossed excitotoxic lesions to the Prh and the contralateral IC (contralateral group). This group's performance was compared to that of rats with ipsilateral Prh and IC lesions (ipsilateral group) and to that of control-operated rats. All the animals received a 0.3% saccharin solution for fifteen minutes on five consecutive days. Rats with contralateral Prh-IC lesions drank significantly higher amounts of saccharin than the other groups during the first encounter with the novel taste, indicating a disruption in neophobia. However, the lesions did not disrupt attenuation of neophobia, with the contralateral group reaching asymptote in trial 2 and the rest of the groups after 3-5 days of exposure to the saccharin. These findings suggest that both Prh and IC play a necessary role in taste neophobia. Additionally, the two cortices function interdependently and their interaction is critical for normal expression of taste neophobia.

Perirhinal cortex supports both taste neophobia and its attenuation.

Rats are often reluctant to consume novel tastes because they lack knowledge about the postingestive effects the new foods might have. This paper examines the effect of excitotoxic lesions and temporary inactivation of the perirhinal cortex (Prh), a key region in the recognition memory system, on taste neophobia and its attenuation. Using a two-bottle choice paradigm (saccharin vs water), excitotoxic lesions were found to disrupt taste neophobia to 0.3% and 0.5% saccharin. However, the lesions had no effect when using a concentration of 0.7%, which is qualitatively aversive (expt. 1a-1c). In a second series of experiments the same animals were able to acquire a flavor preference learning on the basis of a flavor-taste association. Lesioned and control rats showed, during a choice test, a clear preference for the flavor associated with saccharin (expt. 2a-2c). Finally, in a third series of experiments, Prh inactivation with lidocaine after trial 1 (expt. 3) and after trials 1-3 (expt. 4) delayed attenuation of the neophobia. These findings suggest that Prh lesions do not significantly affect taste processing/ perception. Prh thus appears to play an essential role in taste neophobia and its attenuation.

RELATIONSHIP between prandial drinking behavior and supersensitivity of salivary glands after superior salivatory nucleus lesions in RATS.

Prandial drinking, an increase in the number of drinking responses and secondary or non-homeostatic polydipsia in the presence of dry food, is typically associated with a deficit in salivary secretion. This study investigates the degree of salivary gland supersensitivity to pilocarpine administration after lesions to the superior salivatory nucleus (SSN), the site of origin of the parasympathetic preganglionic neurons that innervate the submandibular-sublingual (S-S) salivary glands. The main aim was to determine if there is a relationship between the degree of glandular supersensitivity, as an index of secretory deficit, and the development of prandial drinking in lesioned rats. Results showed that following SSN lesions two subgroups of rats were obtained. One subgroup exhibited prandial drinking but the other was similar to the control group. The SSN-lesioned prandial drinking subgroup presented significantly greater supersensitivity than the SSN-lesioned non-prandial drinking rats; the non-prandial drinking subgroup, in turn, presented significantly more supersensitivity than controls. Additionally, S-S supersensitivity observed in rats that exhibited prandial drinking due to the sectioning of chorda tympani efferent axons was compared to that observed in rats exhibiting prandial drinking due to SSN lesions. It was found that both groups presented the same S-S supersensitivity curve. These results indicate that SSN lesions produce a gradation of S-S supersensitivity values that appear to run parallel to the degree of glandular secretory deficit caused by the lesions. Thus, only the rats with greater secretory deficit (greater supersensitivity) develop prandial drinking. These data support the idea that there is in fact a functional link between the lateral reticular formation of the brainstem (the region associated with the SSN) and S-S salivary glands.

La Personalidad como Vulnerabilidad Unidimensional y Bidimensional: el Papel Mediador de las Variables Cognitivas en la Gravedad Sintomatológica en una Muestra de Personas con Trastorno Grave de Personalidad / Personality as unidimensional and bidimensional vulnerability: The mediator role of cognitive variables in symptom severity in a sample of people with severe personality disorder

Los problemas de conceptualización de los trastornos de personalidad (TP) y su acomodo con el resto de las patologías siguen suscitando un prometedor esfuerzo investigador y clínico que va dando frutos al identificar procesos transdiagnósticos y proponer modelos heurísticos de interacción. Desde el marco de la personalidad como diátesis, estudiamos en una muestra de personas con TP grave (N = 310) el papel mediador de diversas variables en la gravedad sintomatológica. Mediante análisis de conglomerados hallamos una tipología bidimensional que divide de manera exhaustiva y exclusiva al 100% de los participantes. El análisis de mediación revela que el efecto de la personalidad como continuum unidimensional en gravedad sintomatológica está mediado por pensamientos automáticos negativos y fusión cognitiva; su efecto como tipología bidimensional (internalización y externalización) parece mediado solo por pensamientos automáticos. Se discuten los hallazgos e implicaciones de cara al nuevo paradigma de una ciencia clínica basada en procesos

The problems of conceptualization of personality disorders (PD) and their adjustment within the rest of pathologies continue to boost a promising research and clinical effort that helps to identify transdiagnostic processes and suggestheuristic interaction models. Understanting personality from the framework of diathesis, we analized the mediating role of a number of variables in symptom severity in a sample of people with severe PD (N = 310). By means of cluster analysis, we found a two-dimension typology that divides exhaustively and exclusively 100% of the participants. Mediation analyses found that personality as a one-dimension continuum has an effect on symptomatic severity mediated by negative automatic thoughts and by cognitive fusion; its effect as a two-dimension typology (internalization and externalization) appears to be mediated only by automatic thoughts. These findings and their implications are discussed in the context of a new paradigm of a process-based clinical science

Differential Outcome of a Therapeutic Community Program for Internalizing and Externalizing Personality Disorders: A Change in Cognitive Processes Mediates Symptom Improvement / Eficacia diferencial para internalizadores y externalizadores de un programa de comunidad terapéutica para trastornos de personalidad

The identification of transdiagnostic mediating processes involved in a therapeutic change and their relationship with personality can contribute to a better adjustment of a therapeutic technique, enhancing its effectiveness. In a sample of 158 adults diagnosed with personality disorder who complete an inpatient therapeutic community program for 6 months, the hypothesis of a differential reduction in symptom intensity according to the externalizer/internalizer typology is tested, and cognitive variables mediating change are explored. A pre-post change (p = .000, etap2 = .50) is observed, along with a difference between externalizers and internalizers (p = .002, etap2 = .06), and an interaction effect (p = .037, etap2 = .03). The effect of personality type on symptom change (Beta = .43, p = .009) is no longer significant when negative automatic thoughts and dysfunctional attitudes are considered as mediators (Beta = .06, p = .549). Findings are discussed from the perspective of personality disorder as a vulnerability factor

La identificación de procesos mediadores transdiagnósticos intervinientes en el cambio terapéutico y su relación con la personalidad puede contribuir a un mejor ajuste de la técnica terapéutica, potenciando su eficacia. En una muestra de 158 adultos diagnosticados de trastorno de personalidad inscritos en un programa de comunidad terapéutica hospitalaria durante 6 meses se pone a prueba la hipótesis de una reducción diferencial de laintensidad sintomatológica según la tipología externalizador/internalizador y se exploran las variables cognitivas mediadoras del cambio. Se observa un cambio pre-post (p = .000, Etap2 = .50), la diferencia entre externalizadores e internalizadores (p = .002, Etap2 = .06) y el efecto de interacción (p = .037, Etap2 = .03). El efecto del tipo de personalidad sobre el cambio en los síntomas (Beta = .43, p = .009) deja de ser significativo cuando se consideran los pensamientos automáticos negativos y las actitudes disfuncionales (Beta = .06, p = .549) como mediadores. Se discuten los resultados desde la perspectiva del trastorno de personalidad como factor de vulnerabilidad

Fusión Cognitiva en Trastornos de Personalidad: una Contribución a la Investigación sobre Mecanismos de Cambio / Cognitive fusion in personality disorders: A contribution to research on mechanisms of change

Diversos abordajes terapéuticos para personas con trastorno de personalidad (TP) postulan diferentes mecanismos de cambio. Investigamos si el constructo fusión cognitiva (FC) es relevante en el cambio terapéutico detectado en un grupo de personas diagnosticadas de TP grave (N = 110) tras 6 meses de intervención hospitalaria. Su nivel de FC es superior al de otras muestras publicadas (M = 38.5, DT = 8.98) y se asocia a mayor patología. Está relacionado con otros constructos como pensamientos automáticos (r = .529; p < .01) y actitudes disfuncionales (r = .368, p < .01). La FC se reduce tras el tratamiento (t = 4.897, p = .000, d = 0.65), pero no se confirma el supuesto del efecto obstaculizador de la FC sobre el cambio sintomático en la depresión, la perturbación global o la gravedad del TP. Se discuten los hallazgos en el contexto del solapamiento de variables como posible explicación de la constatación de que diferentes terapias produzcan beneficios similares y como acicate para seguir construyendo una práctica terapéutica basada en la evidencia

Different therapeutic approaches for people with personality disorder (PD) hypothesize different mechanisms of change. We studied whether the cognitive fusion (FC) construct is relevant in the therapeutic change identified in a group of people diagnosed with severe PD (N = 110) after 6 months of intervention. The FC level is higher than that of other published samples (M = 38.5, SD = 8.98) and is associated with a more serious pathology. FC is related to other constructs such as automatic thoughts (r = .529, p < .01) and dysfunctional attitudes (r = .368, p < .01). The FC level is reduced after treatment (t = 4.897, p = .000, d = 0.65), but the hypothesized hindering effect of FC on the symptomatic change in depression, global disturbance, or severity of TP is not supported. The findings are discussed in the context of the overlapping of variables as a possible explanation for the observation that different therapies produce similar benefits and as an incentive to continue building an evidence-based therapeutic practice

Actitudes disfuncionales en pacientes con trastorno grave de personalidad: inespecificidad sintomatológica y cambio / Dysfunctional attitudes in patients with severe personality disorder: Symptom non-specificity and change

Se ha descrito una gran concurrencia entre los trastornos afectivos y de personalidad, produciéndose una interacción entre ambos que ensombrece el pronóstico. Examinamos el papel de las actitudes disfuncionales (AD) en esa interacción, analizando diversas variables de autoinforme en personas con diagnóstico de trastorno de personalidad (TP) (n = 262) con y sin depresión. No hallamos diferencias por edad, sexo ni adherencia. Las AD aparecen asociadas a sintomatología depresiva, gravedad general y de TP, rasgos patológicos (sobre todo límites y autodestructivos, con un tamaño del efecto d > 0.80) y, en sentido inverso, a autoeficacia, autoestima y habilidades sociales. Quienes consiguen revertir las AD tras una intervención hospitalaria de 6 meses (el 37.4%) obtienen mejores resultados. Una perspectiva no lineal ayuda a explicar la compleja interacción entre el sentido incrementado de agencia personal e interpersonal (promotor de cambio conductual), las AD (esquema cognitivo) y la preservación del bienestar (homeostasis afectiva)

The frequent co-occurrence of affective and personality disorders (PD) is associated with poor prognosis. We examined the role of dysfunctional attitudes (DA) in this interaction, analysing different self-reporting variables in people with a diagnosis of PD (n = 262) with and without depression. We found no differences by age, sex, or therapeutic adherence; DA are associated with depressive symptoms, general and PD severity, pathological traits (especially borderline and self-destructive, with d > 0.80) and, in the opposite way, with self-efficacy, self-esteem, and social competence. Those who manage to reverse DA after 6 months’ intervention (37.4%) also obtained a better outcome. A non-linear perspective may help explain the complex interaction between the increased sense of personal and interpersonal agency (preparing behavioural change), DA (cognitive schemata), and the preservation of well-being (emotional homeostasis)

Influence of Core Affect in the Differential Efficacy of a Personality Disorder Intervention Program.

The usual emotional experience of the person (affective style) is an influential factor in therapeutic assimilation. Based on a dynamic model of affect shaped dimensionally by the valence and arousal axes (core affect) that fluctuate over time according to the specific context of the individual, its relationship with different variables was investigated and the changes after a 6-month intervention in a specialized hospital unit (N = 103) were observed. The orthogonal structure of core-affect was confirmed. Emotional valence appeared to be positively related to social skills (r = .375; p < .01) and self-esteem (r = .491; p < .01) and negatively to depressive symptoms (r = -.631; p < .01), general disturbance (r = -.395; p < .01) and suicidality (r = -.490; p < .01). Emotional arousal is associated with impulsivity (r = .345; p < .01). The group of patients with an affective style characterized by negative valence and low arousal core-affect gained less therapeutic benefit compared to those with positive valence core-affect (p < .05). Throughout the treatment, valence became more positive (d = .26; IC 95%: 1.9 - 7.2; p = .001), arousal increased (d = .23; IC 95%: 0.2 - 1.7; p = .015) and variability decreased (d = -.44; IC 95%: (-2.9) - (-1.1); p = .001). Changes in the core-affect are related to therapeutic improvement. Adjusting expectations of change can reduce therapeutic frustration, which is as common as it is harmful in the treatment of severe personality disorders.

Perirhinal cortex involvement in allocentric spatial learning in the rat: Evidence from doubly marked tasks.

It has recently been suggested that the different cortices of the medial temporal lobe support a mixture of object and spatial processing functions, challenging the anterior model that emphasized a strict functional differentiation between regions. However, for some structures, the perirhinal cortex (Prh) for example, a number of studies using lesion methods have shown a profound deficit exclusively in tasks involving object learning but not allocentric spatial learning. It may be that the learning paradigms used in previous studies have not been sensitive enough to detect a possible allocentric deficit in Prh-lesioned animals. To examine whether Prh lesions critically affect allocentric spatial learning, experimental and control rats were trained in two doubly marked navigation tasks. In experiment 1, the use of either one of two different memory systems, allocentric versus egocentric, made it possible to locate the goal arm in a four-arm radial maze. In experiment 2, rats had to choose between an allocentric versus a S-R/habit strategy, both of which predicted the location of the goal arm. Results showed that both experimental and control animals learned both navigation tasks well, reaching the same level of performance at the end of training. However, a probe test performed 1 day after the learning ended revealed that Prh-damaged animals learned both tasks predominantly using a non-allocentric strategy. Specifically, in lesioned subjects the percentage of egocentric correct responses (experiment 1) and the percentage of habit-based correct responses (experiment 2) was significantly higher than in the control rats. On the other hand, in both experiments, control rats in the probe test presented a significantly higher number of allocentric correct responses than the lesioned subjects. These results clearly suggest that Prh is normally needed for using allocentric strategies in order to solve a navigation problem. © 2017 Wiley Periodicals, Inc.

Gravedad y cambio en los trastornos de la personalidad / Severity and change in personality disorders

El variado curso que caracteriza la evolución de los trastornos de la personalidad (TP) y la respuesta diversa de los pacientes a las intervenciones terapéuticas hacen que el concepto de gravedad de los TP esté en el debate actual de clínicos e investigadores. En un trabajo previo (Ramos, Sendra, Sánchez y Mena, 2015) propusimos un índice de gravedad basado en el solapamiento de rasgos patológicos; ahora analizamos el cambio en gravedad tras un tratamiento especializado de 6 meses. En 93 pacientes que completaron el programa (51,4% de la muestra total) hallamos una reducción de la perturbación general (d= 1,193) y afectiva (d= 0,990), de rasgos de TP y de gravedad (d= 0,753). Sin embargo, no aparecen efectos de interacción entre cambio y gravedad, ni ésta predice por sí sola el resultado terapéutico. Se discuten los datos a la luz de otros hallazgos. La estabilidad de los TP no parece residir en el cumplimiento de criterios diagnósticos, sino en un núcleo de vulnerabilidad compartido por todos los pacientes, independientemente de su categorización prototípica y de su fluctuación sintomatológica

The varied course of evolution of personality disorders (PD) and patients’ different responses to therapeutic interventions position the concept of severity of PD amongst the greatest concerns to clinicians and researchers. In a previous study (Ramos, Sendra, Sánchez, & Mena, 2015) we proposed an index of severity of PD based on the overlap of pathological traits; now we analyze the change in severity after 6 months of specialized treatment. In 93 patients who completed the program (51.4% of the total sample) we found a reduction in general (d=1.193) and affective (d= 0.990) disturbance, also in PD traits and severity (d=0.753). Nevertheless, interaction effects between change and severity did not appear; neither did severity by itself predict therapeutic results. We discuss the data in the light of other findings. The stability of the PD does not seem to reside in the fulfillment of diagnostic criteria, but in a core of vulnerability shared by all the patients, independently of the prototypical categorization and the symptomatology fluctuation

Influence of core affect in the differential efficacy of a personality disorder intervention program

The usual emotional experience of the person (affective style) is an influential factor in therapeutic assimilation. Based on a dynamic model of affect shaped dimensionally by the valence and arousal axes (core affect) that fluctuate over time according to the specific context of the individual, its relationship with different variables was investigated and the changes after a 6-month intervention in a specialized hospital unit (N = 103) were observed. The orthogonal structure of core-affect was confirmed. Emotional valence appeared to be positively related to social skills (r = .375; p < .01) and self-esteem (r = .491; p < .01) and negatively to depressive symptoms (r = -.631; p < .01), general disturbance (r = -.395; p < .01) and suicidality (r = -.490; p < .01). Emotional arousal is associated with impulsivity (r = .345; p < .01). The group of patients with an affective style characterized by negative valence and low arousal core-affect gained less therapeutic benefit compared to those with positive valence core-affect (p < .05). Throughout the treatment, valence became more positive (d = .26; IC 95%: 1.9 - 7.2; p = .001), arousal increased (d = .23; IC 95%: 0.2 - 1.7; p = .015) and variability decreased (d = -.44; IC 95%: (-2.9) - (-1.1); p = .001). Changes in the core-affect are related to therapeutic improvement. Adjusting expectations of change can reduce therapeutic frustration, which is as common as it is harmful in the treatment of severe personality disorders (AU)

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Perirhinal cortex supports tactual discrimination tasks with increasing levels of complexity: Retrograde effect.

Recent studies have suggested that the perirhinal cortex (Prh) supports representations of feature conjunctions in the visual modality during the acquisition/encoding of complex discriminations. To extend this idea to other sensory modalities and to another stage of the discrimination process, we studied the effect of Prh lesions on the expression of a series of tactual discrimination tasks learned preoperatively. These tasks differed from one another in the degree of feature overlap of the stimuli and in the difficulty of the task. During pre- and post-operative testing phases, rats had to discriminate among 3 stimuli simultaneously exposed in 3 arms of a 4-arm plus-shaped maze. Prh-damaged rats showed a profound impairment in the expression of tactual discrimination tasks when the stimuli had a high or intermediate degree of feature ambiguity, but not when they had a low degree of ambiguity (experiments 1a-1c). In order to experimentally dissociate between subregions within the medial temporal lobe, experiment 2 was conducted to show that hippocampal lesions did not cause any impairment in task expression even when the stimuli had a high degree of feature ambiguity. When the tactual discrimination tasks used simple/individual nonoverlapping features of the stimuli (size), Prh lesions did not affect the expression of these discriminations despite the high level of difficulty of these tasks (experiments 3a and 3b). These findings suggest that, in the somatosensory modality, the Prh plays an essential role in the processing of complex stimuli with overlapping features but not in simple tactual discriminations. Furthermore, the Prh is necessary not just during acquisition but also during expression/performance of the discrimination task.

Pertubación sintomática general y afectiva en los trastornos de la personalidad: influencia de la gravedad frente al tipo de trastorno / General and affective symptoms disturbance in personality disorder: influence of severity vs. type of disorder

Diversos modelos centrados en la gravedad del trastorno de personalidad (TP) se erigen como alternativa a los tradicionales planteamientos categoriales, confirmando su alto valor predictivo en la evaluación del funcionamiento social y en la comorbilidad con otros trastornos. En este trabajo examinamos la relación entre gravedad del TP (acumulación de diferentes rasgos de personalidad patológica e intensidad de cada uno de ellos) y grado de malestar sintomático en una muestra de 142 pacientes. El análisis bivariante confirma en el grupo de alta gravedad un mayor nivel de perturbación general (p= 0,013) y afectiva (p= 0,036). El análisis multivariante detecta, sin embargo, que la intensidad de rasgos esquizotípicos, autodestructivos y pasivo-agresivos explica la perturbación sintomática mejor que la acumulación de rasgos de personalidad patológica. Se discuten estos hallazgos en el contexto de la complejidad conceptual y evaluativa del constructo TP. La búsqueda de un índice adecuado de gravedad sigue pendiente en el esfuerzo por mejorar la planificación y una provisión objetiva de recursos sociosanitarios

Several models focused on the severity of personality disorders (PD) have been proposed as an alternative to the traditional categorical approach, confirming their high predictive value in the evaluation of social functioning and comorbidity with other disorders. In this work, we examined the relationship between personality severity (accumulation of different traits of pathological personality and intensity of each of them) and degree of symptomatic disturbance in a sample of 142 patients. The bivariate analysis confirms that the high personality severity group has higher level of affective (p= .036) and general (p=.013) disruption. However, multivariate analysis found that the intensity of schizotypal, self-destructive and passive-aggressive traits explains symptomatic disturbance better than the accumulation of traits. These findings are discussed in the context of conceptual and evaluative complexity of the personality disorder construct. The search for an appropriate index of severity is still pending in the effort to improve the planning and objective provision of social and health resources

Differential contribution of perirhinal cortex and hippocampus to taste neophobia: effect of neurotoxic lesions.

Although the perirhinal cortex (Prh) has been extensively related to recognition memory, little is known about its specific role in taste memories. The main aim of the present series was therefore to examine the effect of neurotoxic lesions of the Prh on taste neophobia, a phenomenon consisting of a low intake of a novel food until its postingestive consequences are determined. The results showed that Prh-lesioned rats consumed significantly more novel saccharin in trial 1 than control subjects when a saccharin solution of 0.3% (expt. 1a) and 0.5% (expt. 1b) was presented. However, when the saccharin concentration was high and qualitatively more aversive, Prh lesions did not affect the neophobic response (0.7%, expt. 1c) and the lesioned and control animals consumed a similar amount of the fluid during the first and subsequent test trials. In all three experiments, Prh-lesioned and control rats showed a comparable intake at asymptote. Experiment 2 and 3 showed that neurotoxic lesions to the dorsal hippocampus prior to or 24h after the intake of the novel taste (0.3% saccharin) had no effect on the initial occurrence of the neophobic response or on the consolidation of safe taste memory, respectively. These findings support a dissociation of functions between the Prh and the hippocampus in taste neophobia. Also, the data suggests that the Prh plays an essential role in detecting the novelty of the new tastant.

Perirhinal cortex lesions attenuate stimulus generalization in a tactual discrimination task in rats.

Response generalization to a novel stimulus occurs when the new stimulus shares common features with the stimulus used in the original learning. Given the many recent studies suggesting that the perirhinal cortex is critical for disambiguating stimuli that share representational/perceptual elements, we hypothesize that lesions sustained to this region would attenuate response generalization. In the first part of this experiment lesioned and control rats learned a feature-ambiguous tactual discrimination task until they had all reached the same level of performance. In this task animals were asked to discriminate among 3 tactual stimuli simultaneously exposed in 3 arms of a 4-arm plus-shaped maze. In the second part of this experiment, the same rats were given a generalization test 24 h after acquisition of the tactual discrimination. In the generalization test the original tactual stimulus associated with reward during the learning of the discrimination was replaced by a novel tactual stimulus while the other two remained the same. Of the 3 stimuli used in the generalization test, the novel stimulus had the highest degree of feature overlap with respect to the original target stimulus used during the learning of the discrimination. The generalization test took place over two consecutive days, with 8 trials each day. On the first day of generalization, the results indicated that the lesioned rats generalized significantly worse than the control rats during the first 4 trials, but not during the last 4 trials. On the second day of generalization, however, both groups performed the test perfectly. These findings suggest that, in addition to the well-known mnesic function in object processing, the perirhinal cortex may also be involved in perceptual functions.