130,519 research outputs found
Individual differences in response to positive and negative stimuli: endocannabinoid-based insight on approach and avoidance behaviors
No full textApproach and avoidance behaviors - the primary responses to the environmental stimuli of danger, novelty and reward - are associated with the brain structures that mediate cognitive functionality, reward sensitivity and emotional expression. Individual differences in approach and avoidance behaviors are modulated by the functioning of amygdaloid-hypothalamic-striatal and striatal-cerebellar networks implicated in action and reaction to salient stimuli. The nodes of these networks are strongly interconnected and by acting on them the endocannabinoid and dopaminergic systems increase the intensity of appetitive or defensive motivation. This review analyzes the approach and avoidance behaviors in humans and rodents, addresses neurobiological and neurochemical aspects of these behaviors, and proposes a possible synaptic plasticity mechanism, related to endocannabinoid-dependent long-term potentiation and depression that allows responding to salient positive and negative stimuli
Effects of endocannabinoid and endovanilloid systems on aversive memory extinction
No full textIn contextual fear conditioning animals have to integrate various elemental stimuli into a coherent representation of the condition and then associate context representation with punishment. Although several studies indicated the modulating role of endocannabinoid system (ECS) on the associative learning, ECS effect on contextual fear conditioning requires further investigations. The present study assessed the effects of the increased endocannabinoid anandamide (AEA) tone on acquisition, retrieval and extinction of the contextual fear conditioning. Given that AEA may bind to cannabinoid type 1 (CB1) receptors as well as to postsynaptic ionotropic Transient Receptor Potential Vanilloid type 1 (TRPV1) channels, particular attention was paid in determining how the increased AEA tone influenced fear responses. Furthermore, it was investigated how the ECS modulated the effects of stress-sensitization on fear response. Thus, mice submitted or not to a social defeat stress protocol were treated with drugs acting on ECS, CB1 receptors or TRPV1 channels and tested in a contextual fear conditioning whose conditioning, retrieval and extinction phases were analyzed. ECS activation influenced the extinction process and contrasted the stress effects on fear memory. Furthermore, CB1 receptor antagonist blocked and TRPV1 channel antagonist promoted short- and long-term extinction. The present study indicates that ECS controls the extinction of aversive memories in the contextual fear conditioning
Effects of endocannabinoid and endovanilloid systems on aversive memory extinction
No full textIn contextual fear conditioning animals have to integrate various elemental stimuli into a coherent representation of the condition and then associate context representation with punishment. Although several studies indicated the modulating role of endocannabinoid system (ECS) on the associative learning, ECS effect on contextual fear conditioning requires further investigations. The present study assessed the effects of the increased endocannabinoid anandamide (AEA) tone on acquisition, retrieval and extinction of the contextual fear conditioning. Given that AEA may bind to cannabinoid type 1 (CB1) receptors as well as to postsynaptic ionotropic Transient Receptor Potential Vanilloid type 1 (TRPV1) channels, particular attention was paid in determining how the increased AEA tone influenced fear responses. Furthermore, it was investigated how the ECS modulated the effects of stress-sensitization on fear response. Thus, mice submitted or not to a social defeat stress protocol were treated with drugs acting on ECS, CB1 receptors or TRPV1 channels and tested in a contextual fear conditioning whose conditioning, retrieval and extinction phases were analyzed. ECS activation influenced the extinction process and contrasted the stress effects on fear memory. Furthermore, CB1 receptor antagonist blocked and TRPV1 channel antagonist promoted short- and long-term extinction. The present study indicates that ECS controls the extinction of aversive memories in the contextual fear conditioning. (C) 2013 Elsevier B.V. All rights reserved
Alexithymia: From neurobiological basis to clinical implications
No full textAlexithymia is a construct of personality characterized by impairment in cognitive, emotional and affective processing. It describes people with deficiencies in identifying, processing, or describing subjective feelings or emotions. Although alexithymia is not a psychological disorder per se and it is normally distributed in healthy population, it is associated with enhanced risk of psychological impairment and it is present in a broad spectrum of psychiatric and psychosomatic disorders, as chronic pain, somatoform disorders, addictive disorders, anxiety and depression. By using neuroimaging studies, variations associated with functional and structural differences in people with high alexithymic traits are described in most of brain areas related to emotional awareness, as anterior cingulate cortex, fusiform gyrus, amygdala, parahippocampal gyrus and insula. Further, in the presence of alexithymia alterations are evidenced in the somato-sensory and sensorimotor cortices as well as in cerebellar areas. The link between limbic and somato-sensory systems may represent the possible neuroanatomical correlate of alexithymia. In the present chapter, the neurobiological basis and clinical implications of alexithymia are examined to clarify how the altered cognitive and affective experience of emotion may result in a deficit in the emotional awareness
Cross sections for the two-step radiative decay process X(v) → A(v′′) → X(v′) in e-LiH collisions
No full textAbstract: The cross sections for the two-step process, represented by the electron-impact vibro-electronic excitation X1Σ+(v) → A1Σ+(v′ ′) of the LiH molecule, followed by radiative decay back on the vibrational manifold of the ground state, A1Σ+(v′ ′) → X1Σ+(v′) , are calculated as a function of the incident electron energy from the threshold to 1000 eV. The final cross sections for the two-step process, which results in an overall vibrational excitation of the molecule, known also as E-v process, are provided for all the possible v, v′ transitions among the vibrational levels, including the continuum, of the electronic ground state. Graphic abstract: [Figure not available: see fulltext.
Cerebellar Damage Loosens the Strategic Use of the Spatial Structure of the Search Space
No full textElectron-impact excitation cross sections of vibrationally excited X (1)Sigma(+)(g) H-2 and D-2 molecules to Rydberg states
No full textA complete set of total and dissociative electron-impact cross sections of vibrationally excited H-2 and D-2 molecules has been calculated by using the impact-parameter method. Transitions to low-lying Rydberg states (X-->B' ,X-->B ", X-->D, X-->D') are considered. Finally, vibrational and mass scaling relations, able to reproduce the calculated cross sections, are presented. [S1050-2947(99)00609-5]
Behavioral and electrophysiological effects of endocannabinoid and dopaminergic systems on salient stimuli
No full textRewarding effects have been related to enhanced dopamine (DA) release in corticolimbic and basal ganglia structures. The DAergic and endocannabinoid interaction in the responses to reward is described. This study investigated the link between endocannabinoid and DAergic transmission in the processes that are related to response to two types of reward, palatable food and novelty. Mice treated with drugs acting on endocannabinoid system (ECS) (URB597, AM251) or DAergic system (haloperidol) were submitted to approach-avoidance conflict tasks with palatable food or novelty. In the same mice, the cannabinoid type-1 (CB1)-mediated GABAergic transmission in medium spiny neurons of the dorsomedial striatum was analyzed. The endocannabinoid potentiation by URB597 magnified approach behavior for reward (food and novelty) and in parallel inhibited dorsostriatal GABAergic neurotransmission. The decreased activity of CB1 receptor by AM251 (alone or with URB597) or of DAergic D2 receptor by haloperidol had inhibitory effects toward the reward and did not permit the inhibition of dorsostriatal GABAergic transmission. When haloperidol was coadministered with URB597, a restoration effect on reward and reward-dependent motor activity was observed, only if the reward was the palatable food. In parallel, the coadministration led to restoring inhibition of CB1-mediated GABAergic transmission. Thus, in the presence of simultaneous ECS activation and inhibition of DAergic system the response to reward appears to be a stimulus-dependent manner
Macro- and micro-structural cerebellar and cortical characteristics of cognitive empathy towards fictional characters in healthy individuals
No full textFew investigations have analyzed the neuroanatomical substrate of empathic capacities in healthy subjects, and most of them have neglected the potential involvement of cerebellar structures. The main aim of the present study was to investigate the associations between bilateral cerebellar macro- and micro-structural measures and levels of cognitive and affective trait empathy (measured by Interpersonal Reactivity Index, IRI) in a sample of 70 healthy subjects of both sexes. We also estimated morphometric variations of cerebral Gray Matter structures, to ascertain whether the potential empathy-related peculiarities in cerebellar areas were accompanied by structural differences in other cerebral regions. At macro-structural level, the volumetric differences were analyzed by Voxel-Based Morphometry (VBM)- and Region of Interest (ROI)-based approaches, and at a micro-structural level, we analyzed Diffusion Tensor Imaging (DTI) data, focusing in particular on Mean Diffusivity and Fractional Anisotropy. Fantasy IRI-subscale was found to be positively associated with volumes in right cerebellar Crus 2 and pars triangularis of inferior frontal gyrus. The here described morphological variations of cerebellar Crus 2 and pars triangularis allow to extend the traditional cortico-centric view of cognitive empathy to the cerebellar regions and indicate that in empathizing with fictional characters the cerebellar and frontal areas are co-recruited
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