Lexical-semantic processing in the semantic priming paradigm in aphasic patients

There is evidence that the explicit lexical-semantic processing deficits which characterize aphasia may be observed in the absence of implicit semantic impairment. The aim of this article was to critically review the international literature on lexical-semantic processing in aphasia, as tested through the semantic priming paradigm. Specifically, this review focused on aphasia and lexical-semantic processing, the methodological strengths and weaknesses of the semantic paradigms used, and recent evidence from neuroimaging studies on lexical-semantic processing. Furthermore, evidence on dissociations between implicit and explicit lexical-semantic processing reported in the literature will be discussed and interpreted by referring to functional neuroimaging evidence from healthy populations. There is evidence that semantic priming effects can be found both in fluent and in non-fluent aphasias, and that these effects are related to an extensive network which includes the temporal lobe, the pre-frontal cortex, the left frontal gyrus, the left temporal gyrus and the cingulated cortex.

Surgical and postmortem pathology studies: contribution for the investigation of temporal lobe epilepsy

Pathology studies in epilepsy patients bring useful information for comprehending the physiopathology of various forms of epilepsy, as well as aspects related to response to treatment and long-term prognosis. These studies are usually restricted to surgical specimens obtained from patients with refractory focal epilepsies. Therefore, most of them pertain to temporal lobe epilepsy (TLE) with mesial temporal sclerosis (MTS) and malformations of cortical development (MCD), thus providing information of a selected group of patients and restricted regions of the brain. Postmortem whole brain studies are rarely performed in epilepsy patients, however they may provide extensive information on brain pathology, allowing the analysis of areas beyond the putative epileptogenic zone. In this article, we reviewed pathology studies performed in epilepsy patients with emphasis on neuropathological findings in TLE with MTS and MCD. Furthermore, we reviewed data from postmortem studies and discussed the importance of performing these studies in epilepsy populations.

Enhancement of behavioral sensitization, anxiety-like behavior, and hippocampal and frontal cortical CREB levels following cocaine abstinence in mice exposed to cocaine during adolescence

Adolescence has been linked to greater risk-taking and novelty-seeking behavior and a higher prevalence of drug abuse and risk of relapse. Decreases in cyclic adenosine monophosphate response element binding protein (CREB) and phosphorylated CREB (pCREB) have been reported after repeated cocaine administration in animal models. We compared the behavioral effects of cocaine and abstinence in adolescent and adult mice and investigated possible age-related differences in CREB and pCREB levels. Adolescent and adult male Swiss mice received one daily injection of saline or cocaine (10 mg/kg, i.p.) for 8 days. On day 9, the mice received a saline injection to evaluate possible environmental conditioning. After 9 days of withdrawal, the mice were tested in the elevated plus maze to evaluate anxiety-like behavior. Twelve days after the last saline/cocaine injection, the mice received a challenge injection of either cocaine or saline, and locomotor activity was assessed. One hour after the last injection, the brains were extracted, and CREB and pCREB levels were evaluated using Western blot in the prefrontal cortex (PFC) and hippocampus. The cocaine-pretreated mice during adolescence exhibited a greater magnitude of the expression of behavioral sensitization and greater cocaine withdrawal-induced anxiety-like behavior compared with the control group. Significant increases in CREB levels in the PFC and hippocampus and pCREB in the hippocampus were observed in cocaine-abstinent animals compared with the animals treated with cocaine in adulthood. Interestingly, significant negative correlations were observed between cocaine sensitization and CREB levels in both regions. These results suggest that the behavioral and neurochemical consequences of psychoactive substances in a still-developing nervous system can be more severe than in an already mature nervous system

Distribution of water masses and diapycnal mixing in the Cape Verde Frontal Zone

[EN]The Cape Verde Frontal Zone separates North and South Atlantic Central Waters in the eastern North Atlantic Subtropical Gyre. CTD-O2 and shipboard ADCP data from three hydrographic sections carried out in September 2003 are used to study the structure of the front. Results show the relation between spatial variations of water masses and currents, demonstrating the importance of advection in the distribution of water masses. Diapycnal diffusivities due to double diffusion and vertical shear instabilities are also estimated. Existence of competition between the two processes through the water column is shown. Depth-averaged diffusivities suggest that salt fingering dominates diapycnal mixing, except areas of purest South Atlantic Central Water. Here, double diffusion processes are weak and, consequently, shear of the flow is the main process. Results also show that strong mixing induced by vertical shear is associated with a large intrusion found near the front.

Spontaneous recovery of visually-triggered saccades after focal lesions of the frontal and parietal eye fields: A combined longitudinal oculomotor and fMRI study

To analyze oculomotor recovery in a patient with ischemic lesions restricted to the left frontal eye field (FEF) and the left parietal eye field (PEF).

Occurrence, types and severity of associated injuries of paediatric patients with fractures of the frontal skull base

To clarify the occurrence, sites, and types of associated injuries in paediatric patients with fractures of the anterior skull base.

Frontal white matter integrity is related to psychomotor retardation in major depression

Altered frontal white matter integrity has been reported in major depression. Still, the behavioral correlates of these alterations are not established. In healthy subjects, motor activity correlated with white matter integrity in the motor system. To explore the relation of white matter integrity and motor activity in major depressive disorder, we investigated 21 medicated patients with major depressive disorder and 21 matched controls using diffusion tensor imaging and wrist actigraphy at the same day. Patients had lower activity levels (AL) compared with controls. Fractional anisotropy (FA) differed between groups in frontal white matter regions and the posterior cingulum. AL was linearly associated with white matter integrity in two clusters within the motor system. Controls had an exclusive positive association of FA and AL in white matter underneath the right dorsal premotor cortex. Only patients had a positive association within the posterior cingulum. Furthermore, patients had negative associations of FA and AL underneath the left primary motor cortex and within the left parahippocampal gyrus white matter. These differences in the associations between structure and behavior may contribute to well-known impaired motor planning or gait disturbances in major depressive disorder. Therefore, signs of psychomotor slowing in major depressive disorder may be linked to changes of the white matter integrity of the motor system.

Mental reversal of imagined melodies: A role for the posterior parietal cortex

Two fMRI experiments explored the neural substrates of a musical imagery task that required manipulation of the imagined sounds: temporal reversal of a melody. Musicians were presented with the first few notes of a familiar tune (Experiment 1) or its title (Experiment 2), followed by a string of notes that was either an exact or an inexact reversal. The task was to judge whether the second string was correct or not by mentally reversing all its notes, thus requiring both maintenance and manipulation of the represented string. Both experiments showed considerable activation of the superior parietal lobe (intraparietal sulcus) during the reversal process. Ventrolateral and dorsolateral frontal cortices were also activated, consistent with the memory load required during the task. We also found weaker evidence for some activation of right auditory cortex in both studies, congruent with results from previous simpler music imagery tasks. We interpret these results in the context of other mental transformation tasks, such as mental rotation in the visual domain, which are known to recruit the intraparietal sulcus region, and we propose that this region subserves general computations that require transformations of a sensory input. Mental imagery tasks may thus have both task or modality-specific components as well as components that supersede any specific codes and instead represent amodal mental manipulation.

Effect of unilateral temporal-lobe excision on perception and imagery of songs

Auditory imagery for songs was studied in two groups of patients with left or right temporal-lobe excision for control of epilepsy, and a group of matched normal control subjects. Two tasks were used. In the perceptual task, subjects saw the text of a familiar song and simultaneously heard it sung. On each trial they judged if the second of two capitalized lyrics was higher or lower in pitch than the first. The imagery task was identical in all respects except that no song was presented, so that subjects had to generate an auditory image of the song. The results indicated that all subjects found the imagery task more difficult than the perceptual task, but patients with right temporal-lobe damage performed significantly worse on both tasks than either patients with left temporal-lobe lesions or normal control subjects. These results support the idea that imagery arises from activation of a neural substrate shared with perceptual mechanisms, and provides evidence for a right temporal- lobe specialization for this type of auditory imaginal processing.

Limitations of balloon sinuplasty in frontal sinus surgery

Balloon sinuplasty is a tool that is used to treat selected patients with paranasal sinus pathologies. No studies have investigated the aetiology of failed access to the frontal sinus. The aim of our study was to specify the intraoperative technical failure rate and to analyse the aetiology of the failed access to predict potential technical difficulties before surgery. We retrospectively analysed the charts of patients who underwent balloon sinuplasty from November 2007 to July 2010 at three different ENT-Centres. CT-analysis of the patients with failed access was performed. Of the 104 frontal sinuses, dilation of 12 (12%) sinuses failed. The anatomy of all failed cases revealed variations in the frontal recess (frontoethmoidal-cell, frontal-bulla-cell or agger-nasi-cell) or osteoneogenesis. In one patient, a lymphoma was overlooked during a balloon only procedure. The lymphoma was diagnosed 6 months later with a biopsy during functional endoscopic sinus surgery. In complex anatomical situations of the frontal recess, balloon sinuplasty may be challenging or impossible. In these situations, it is essential to have knowledge of classical functional endoscopic sinus surgery of the frontal recess area. The drawbacks of not including a histopathologic exam should be considered in balloon only procedures.

Hearing in the mind's ear: A PET investigation of musical imagery and perception

Neuropsychological studies have suggested that imagery processes may be mediated by neuronal mechanisms similar to those used in perception. To test this hypothesis, and to explore the neural basis for song imagery, 12 normal subjects were scanned using the water bolus method to measure cerebral blood flow (CBF) during the performance of three tasks. In the control condition subjects saw pairs of words on each trial and judged which word was longer. In the perceptual condition subjects also viewed pairs of words, this time drawn from a familiar song; simultaneously they heard the corresponding song, and their task was to judge the change in pitch of the two cued words within the song. In the imagery condition, subjects performed precisely the same judgment as in the perceptual condition, but with no auditory input. Thus, to perform the imagery task correctly an internal auditory representation must be accessed. Paired-image subtraction of the resulting pattern of CBF, together with matched MRI for anatomical localization, revealed that both perceptual and imagery. tasks produced similar patterns of CBF changes, as compared to the control condition, in keeping with the hypothesis. More specifically, both perceiving and imagining songs are associated with bilateral neuronal activity in the secondary auditory cortices, suggesting that processes within these regions underlie the phenomenological impression of imagined sounds. Other CBF foci elicited in both tasks include areas in the left and right frontal lobes and in the left parietal lobe, as well as the supplementary motor area. This latter region implicates covert vocalization as one component of musical imagery. Direct comparison of imagery and perceptual tasks revealed CBF increases in the inferior frontal polar cortex and right thalamus. We speculate that this network of regions may be specifically associated with retrieval and/or generation of auditory information from memory.