Chlorpheniramine facilitates inhibitory avoidance in teleosts submitted to telencephalic ablation

The present study investigated the involvement of H(1) histaminegic receptor on the acquisition of inhibitory avoidance in Carassius auratus submitted to telencephalic ablation. The fish were submitted to telencephalic ablation 5 days before the experiment. The inhibitory avoidance procedure included 1 day for habituation, 3 days for training composed of 3 trials each (1st day: T1, T2, T3; 2nd day: 2T1, 2T2, 2T3; 3rd day: 3T1, 3T2, 3T3) and 1 day for test. On training days, the fish were placed in a white compartment, after 30 s the door was opened. When the fish crossed to a black compartment, a weight was dropped (aversive stimuli). Immediately after the third trial, on training days, the fish received, intraperitoneally, one of the pharmacological treatments (saline (N = 20), 8 (N = 12) or 16 (N = 13) µg/g chlorpheniramine, CPA). On the test day, the time to cross to the black compartment was determined. The latency of the saline group increased significantly only on the 3rd trial of the 2nd training day (mean ± SEM, T1 (50.40 ± 11.69), 2T3 (226.05 ± 25.01); ANOVA: P = 0.0249, Dunn test: P < 0.05). The group that received 8 µg/g CPA showed increased latencies from the 2nd training day until the test day (T1 (53.08 ± 17.17), 2T2 (197.75 ± 35.02), test (220.08 ± 30.98); ANOVA: P = 0.0022, Dunn test: P < 0.05)). These results indicate that CPA had a facilitating effect on memory. We suggest that the fish submitted to telencephalic ablation were able to learn due to the local circuits of the mesencephalon and/or diencephalon and that CPA interferes in these circuits, probably due an anxiolytic-like effect.

Cuantificación de la activación cerebral mediante exploración PET relacionada con estados de alerta o relajación / Quantification of the cerebral activation by means of PET exploration related with arousal or relaxation states

En un reciente estudio publicado en esta revista, empleamos una técnica de cuantificación de la actividad PET que nos permite la detección de áreas del cerebro con una actividad patológica frente a una base normativa. En nuestro esfuerzo por comprobar la eficacia del método estamos desarrollando diversos estudios para verificar su validez. En el presente trabajo mostramos que es posible observar la actividad cerebral de un sujeto control en diferentes niveles de alerta. En particular, la actividad de regiones frontales y parietales del hemisferio derecho se encuentran incrementadas como consecuencia de un estado de alerta mayor respecto del estado de relajación.

In a recent study published in this journal, we use a quantification technique for the PET exploration that allows us the detection of areas of the brain with a pathological activity compared to a normative database. In our effort to check the effectiveness of the method diverse studies have been developed to verify the validity of the method. In the present experiment, we show an interesting result that confirms that is possible to observe the brain activity of a healthy control in different levels of arousal. In particular, the activity of frontal and parietal regions of the right hemisphere is enhanced as a consequence of an increased level of arousal compared to the relaxation state.

Determinación estadística de áreas cerebrales patológicas empleando tomografía por emisión de positrones / Statistical analysis of pathological brain areas using positron emission tomography

Los estudios de neuroimagen funcional permiten observar cuáles pueden ser las localizaciones de los diversos procesos neurofisiológicos que son la base de los procesos psicológicos como la memoria, atención, etc. Sin embargo, para un análisis científico y/o clínico de esta relación entre estructura y función es necesario desarrollar métodos de cuantificación que permitan la comprobación de las hipótesis planteadas empleando análisis estadísticos. En el presente trabajo presentamos un método que permite esta cuantificación y lo hemos comprobado tanto en un paciente como en un sujeto control. Los resultados obtenidos invitan a la aplicación del método tanto en estudios científicos como en la práctica clínica.

Functional neuroimaging studies allow knowing the localization of the diverse neurophysiological processes that are the substrate of psychological processes like memory, attention… Nevertheless, in order to do a clinic or scientific analysis of the relation between function and structure is necessary to develop quantification methods to probe the established hypothesis using statistical analysis. In this work we present a method that allow the quantification. This one was used in one Alzheimer disease patient and in one healthy person. This previous results invite to the application of the method in scientific studies and in clinical practice.

Bases psiconeuroendócrinas del dimorfismo sexual cerebral / Psychoneuroendocrine bases for brain sexual dimorphism

Con el avance de las neurociencias, cada vez se conoce más sobre las características morfológicas y funcionales del cerebro, la acción de los neuroesteroides y los aspectos genómicos y no genómicos involucrados en la modulación de las características específicas de cada sexo, con sus aspectos biomorfológicos, fisiológicos, psicológicos y sociales. El presente artículo aborda los avances en el conocimiento del dimorfismo sexual cerebral a fin de intentar comprender estas peculiaridades biológicas y funcionales y su posible influencia en las conductas sanas y en las diferencias sexuales clínicamente evidentes en las formas de expresión, evolución, pronóstico y respuesta al tratamiento de las enfermedades mentales. Pone además el énfasis en el estudio integrativo de la persona, desde un abordaje psiconeuroinmunoendocrinológico.

Neurobiología de las emociones / Neurobiology of emotions

Las emociones son respuestas químicas y neuronales complejas, cuya función fundamental es adaptativa. Ellas organizan tanto el pensamiento como la acción con el fin de evolucionar en vida de la manera más adecuada y óptima. Las emociones se clasifican en primarias y secundarias, siendo las primeras originadas en la amígdala y la corteza singular anterior, las que se dividen en 6 tipos universales, explicando así la similitud de la expresión emocional en todos los individuos y culturas. Las segundas se originan de preferencia en la corteza prefrontal y requieren de la cognición para desarrollarse, dándole un sello social a nuestra personalidad. El sentimiento supone un darse cuenta de las sensaciones básicas de la emoción a través de la interpretación de los cambios en el estado corporal, proceso que se realiza gracias a la integración realizada por la conciencia. En la presente revisión se detallan los mecanismos neurobiológicos y fisiológicos que determinan las diversas emociones humanas, así como las diversas estructuras cerebrales que participan en su configuración, haciendo un recorrido que abarca el binomio tálamo-amigdaliano, corteza prefrontal y hemisferios cerebrales en su rol regulatorio.

Microanatomía de los segmentos M1 y M2 de la arteria cerebral media en hemisferios humanos de origen chileno: correlación con la literatura internacional / Median cerebral artery segments M1 and M2 microanatomy in chilean human hemispheres: correlation with international literature

La arteria cerebral media (ACM) es el más largo y complejo de todos los vasos intracerebrales, irrigando la mayor parte de los lóbulos frontales, parietales y temporales de ambos hemisferios cerebrales. Además de suplir el riego sanguíneo de una gran parte del cerebro, la ACM y sus ramas, están frecuentemente involucradas en enfermedades intracerebrales como hemorragias cerebrales, patología ateroesclerótica o degenerativa de la pared arterial, embolias y procesos inflamatorios. La alta frecuencia de patología y el amplio volumen cerebral irrigado por esta arteria hacen que el conocimiento de su anatomía sea fundamental en la descripción de los posibles mecanismos fisiopatológicos de las enfermedades que la involucran, así como para su estudio imagenológico y abordaje quirúrgico. El objetivo de este trabajo es comparar la anatomía macroscópica y microscópica de la ACM de sujetos chilenos con la publicada en series internacionales. Se estudiaron 10 hemisférios cadavéricos provenientes de 5 pacientes adultos de nacionalidad chilena cuya muerte no fue de causa encefálica, fijados con solución de formalina sometiendo a tinción los vasos arteriales. Se realizaron mediciones de la ACM y sus segmentos M1 y M2 comparando mediante análisis estadístico los resultados obtenidos con los publicados en la literatura. El análisis de éstos sugiere que las características anatómicas de la ACM de hemisferios provenientes de sujetos de nacionalidad chilena son similares a los reportados por estudios realizados con hemisferios cerebrales de sujetos de origen anglo-sajón.

Functional role of a glycolipid in directional movements of neurons

Migration of neurons from their site of origin to their final destination is a critical and universal step in the formation of the complex structure of the nervous system. The migratory process is thought to be governed in part by genetically and epigenetically defined sequences of signals which are interpreted by migrating cells. The molecular mechanisms that underlie neuronal migration have been the subject of intense investigation. As in other developmental processes, many molecules must participate in neuronal migration. Some molecules, such as cell adhesion molecules and motor proteins, may contribute to discrete steps in the migration act; others, like extracellular signaling molecules, may regulate the activation and/or termination of the migration program. In this article we review findings from our group that demonstrate the functional role(s) of a specific glycolipid in neuronal migration and neurite outgrowth in the developing and adult nervous system

Evolutionary origins of the reptilian brain: the question of putative homologues of dorsal ventricular ridge. An overview and proposal

The reptilian brain is characterized by a structure that bulges into the lateral ventricle, called dorsal ventricular ridge (DVR). The DVR was originally considered to be a part of the basal ganglia, although more recent studies indicate that it may correspond to the dorsal part of the hemisphere. The anterior portion of the DVR has several connectional and functional similarities with parts of the mammalian neocortex, for which reason it has been claimed that the two structures can be considered as homologues. In this article I review the evidence supporting and refuting homology of the DVR with different telencephalic structures of mammals, concluding that it is still early to unequivocally ascribe structural correspondences between the different components in the two vertebrate classes. However, a way out of the problem is suggested by comparing the embryonic position of DVR with that of lateral cortex in the reptilian hemisphere. The lateral cortex is considered to be quite comparable in reptiles and mammals, and hence may be a good marker for the original position of the DVR. If the DVR originates dorsal to lateral cortex, it may be considered comparable to parts of the mammalian neocortex, while if it develops in its same position or ventral to it, it may not correspond to the neocortex. Early embryological work indicated that the DVR develops in the same position as the lateral cortex, but arises as a late migration wave, after cells destined to lateral cortex are generated. In other words, instead of being interposed between dorsal and lateral cortices, the DVR may originate in a position overlapping with lateral cortex. If this alternative turns out to be the case, it may imply that the DVR arose de novo, through an extension of the ancestral period of neuroblast proliferation. As a consequence, there may be no structures comparable to it in other vertebrate classes. Finally, it is also proposed that, regardless of whether the DVR and the extrastriate neocortex can or cannot be considered phylogenetic homologues, some of the integrative functions performed by them might have a common evolutionary origin, that became localized in the reptilian DVR and in the mammalian extrastriate neocortex

Significance of studies of the avian brain from three perspectives

The avian brain has been one of the most popular subjects in neuroscience. Recent developments and findings related to avian studies from three different fields are described and their significance is discussed. These topics are: 1) paleontological discoveries indicating that birds are the successors of dinosaurs; 2) neuroanatomical findings indicating that there is a general pattern of information processing in the avian brain; and 3) an evolution hypothesis suggesting that the avian brain has neurons corresponding to those of the mammalian neocortex.

Habituation to sound stimulation in detelencephalated pigeons (Columbia livia)

Habituation to sound stimulation was analyzed in terms of the functional role of the telencephalon in learning. Sixteen pigeons were exposed to 1000-Hz, 83-dB, 1-s sound (stimulus A) at 30-s intervals until there was habituation of the exploratory and pre-exploratory responses. The learning criterion was 10 trials without the occurrence of these responses. Twenty-four hours after habituation to stimulus A the birds were tested with a 500-Hz, 85-dB, 1-s sound (stimulus B). On the day following habituation to stimulus B, the birds of the experimental group (N=8) suffered ablation of the telencephalon and the birds of the control group (N=8) had sham surgery. Retesting with the same sequence of procedures was carried out 10 days after surgery. in the POST-lesion situation there was a decrease of the number of habituation trials to stimulus A (P<0.01) and to stimulus B (P<0.05) by experimental pigeons compared to the PRE-lesion situation. The data suggest an interaction of a facilitatory effect of the lesion and long-term learning effects

Effects of massive telencephalic lesions on the organization of behavior in pigeons (Columba livia)

The effect of massive lesions of the telencephalon on the repertoire of captive pigeons were investigated. The behavior of four birds with an intact telencephalon was compared to that of four birds submitted to ablation of telencephalic structures. Behavioral audio recording was done according to previously defined categories in three daily sessions for fifteen days. Experimental birds were followed up for month. Immediately after the lesion, operated birds showed decreases in the occurrence of different behaviors such as coording movements, feeding, interaction, preening, maintenance, exploration and vocalization and increases in locomotion and discrete movements of the body when compared to the control birds (P<0.05). Recovery of exploration (P<0.05), feeding and localization was during the follow-up period. These data are interpreted as suggestive of a functional role of the telencephalon in the organization of behavior and a long-term recovery of behavior after detelencephalation

Functional characteristics (EEG) of the thalamo-telencephalic projections of toads

Electrical or chemical (carbachol) stimulation of the dorsal thalamus of anesthetized and conscious toads induced synchronization (increased number of spindles and increased amplitude of the waves) in the electric tracing (EEG) of the telencephalon. This alteration was accompanied by mydriasis and greater behavioral alert in conscious animals. No recruitment response was observed in anesthetized toads. The present findings were compared to those obtained by stimulating the nonspecific thalamus of mmmals and reptiles. Even though the data available at present do not demonstrate the existence of a system with the morphological characteristics of the reticulo-thalamo-cortical system of mammals in anurans, the functional data presented here suggest this possibility

Increased susceptibility of detelencephalated rats to audiogenic seizures induced by microinjection of bicuculline into the inferior colliculus

The participation of telencephalic forebrain structures in the induction of audiogenic seizure (AGS) susceptibility and in the behavioral expression of AGS was investigated in rats. Rats that were initially susceptible (N = 12) or non-susceptible (N = 28) to audiogenic seizure were surgically detelencephalated. A unilateral microinjection of a low dose (30 pmol) of the GABA antagonist bicuculline methiodide (BM) was applied to the inferior colliculus (IC) before the animals were exposed to a 120-dB acoustic stimulus. All susceptible rats still exhibited all components of audiogenic seizure after removal of the telencephalon. After BM microinjection, a higher incidence (66% vs 41%) and shorter latencies (6-20 s vs 9-55) s) of occurrence of tonic seizures were observed in the detelencephalated non-susceptible rats when compared to non-operated non-susceptible rats(N = 12). These results suggest that the induction of the behavioral expression of audiogenic seizures issubserved by brain stem neuronal networks but does not require the telencephalon and that telencephalic structures may exert control over audiogenic seizures by inhibiting IC cells through GABAergic neurons

Swimming escape learning in rats with telencephalic lesions

Experiments were conducted to determine whether rats having unilateral or bilateral ablation of either the neocortex or telencephalon can learn to escape from a tank of water by climbing a platform. Hemi - or bilaterally decorticated rats were able to learn the swimming escape task, the same being observed for hemidetelencephalated rats. Fully detelencephalated rats, however, did not exhibit this capability. These results show that integrity of one the cerebral hemispheres is necessary in order to allow swimming escape learning

Telencephalic and pretectal modulation of the directional selectivity of accessory optic neurons in the pigeon

Direction-selective units within the accessory optic system of the pigeon were shown to respond more strongly to motion along two main directions, downward-nasal and upward-temporal. Following ipsilateral telencephalic or pretectal lesions, these directions were modified in a systematic way. In the former, the principal response directions were downward-nasal and temporal and in the latter, downward-temporal and upward-temporal. These data indicate that the non-retinal afferents play an important role in the functional organization of the accessory optic system

Anatomical study of the parrakeet (Aratinga canalicularis)

De estudios recientes sobre la organización del telencéfalo de las aves se sabe que esta estructura tiene muchas similitudes cocn el cerebro de los mamíferos. Tambíen se conoce que la porción del hiperestriado dorsal conocida como la wulst así cocmo la porción lateral, identificada como el lado ventricular dorsal, tiene un papel importante en la integración sensorial, el aprendizaje y la producción del canto en las aves. Aunque ambas estructuras no poseen laminación como la de la neocorteza de los mamíferos, sin embargp, ciertas aves como el búho muestran una clara pseudolaminación. En la literatura no hay descripciones anatómicas de la wulst en preicos, por lo que el objetivo del presente trabajo fue estudiar esta estructura en la ewpecie. Aratinga canicularis. Se identificaron tres tipos celulares y, mediante métodos morfométricos efectuados en un total de 240 células por cada estrato, se midieron 10 parámetros distintos y se distinguieron tres estratos, a los que se les denominó dorsal, medial y ventral. Cada uno de los tres tipos celulares presentaron características específicas. Las células multipolares y triangulares mostraron un patrón dendrítico ramificado y abundantes espinas dendríticas. Las triangulares difieron en cuanto a la extensión de sus dendritas y la ramificación de su axón en ángulos rectos dirigidos hacia el estrato suprayacente. Las células ovoides fueron las mas pequeñas con pocas ramas y espinas. Estas células son similares a las del hiperestriatum accesorio del buho, las que a su vez son análogas a las células granulares de la corteza visual de los mamíferos

A stereotaxic atlas for the telencephalon of the siamese fighting fish (Betta splendens)

1. A stereotaxic technique for electrode positioning in the telencephalic nuclei of the Siamese Fighting fish (Beta splendens) is described. 2. The forebrain atlas was based on paraffin-embedded, in situ-sectioned, Nissl-stained material. Brain measurements were corrected for tissue shrinkage due to histological procedures. The atlas and methods have aledy been tested and have shown good accuracy and reproducibility