Prospective memory and working memory: Asymmetrical effects during frontal lobe TMS stimulation

The role of working memory (WM) for the realization of an intended action (prospective memory, PM) has been debated in recent neuropsychological literature. The present study aimed to assess whether WM and PM share resources or are, alternatively, two distinct mechanisms. A verbal task was used, which manipulated the cognitive demand of both WM and PM dimensions on an event-based prospective task. Transcranial magnetic stimulation (TMS) was also employed to clarify the causal contribution of frontal areas previously related to WM, to the PM process. The prospective task required the participant to respond whenever a word appeared which had been presented before the beginning of the task. Two ongoing tasks were administered: an updating WM task (in two conditions of medium and high WM demands) and a lexical decision task (representing a low WM demand). In the first two experiments, higher PM demand affected WM only at higher loads, but the PM load effect was independent of WM, showing asymmetrical behavioural effects. In the third experiment, single pulse TMS was applied to left and right dorsolateral prefrontal cortices. When applied to the experimental sites, stimulation increased error rates of the PM task, while the effect was only marginal in the WM task. The effect was bilateral, since there was no difference between left and right stimulation sites. These findings demonstrated, from both behavioural and neurofunctional perspectives, that WM and PM processes are not based on the same memory system, but PM may require WM resources at high demand.     

The Recognition of Facial Emotions in Spinocerebellar Ataxia Patients

Patients with cerebellar lesions present some affective and cognitive disorders, defining a peculiar pattern of cognitive impairment, so-called cerebellar cognitive affective syndrome. This pattern has been confirmed in many genotypes of spinocerebellar ataxias (SCA), a group of genetically defined pathologies characterized by the degeneration of the cerebellum and its connections. Recently, in SCA patients, some authors focused the interest on social cognition evidencing an impairment of theory of mind and basic emotion recognition by verbal material. The recognition of emotions in faces is an essential component of social cognition; therefore, we assessed this ability in SCA patients, expanding the study from the basic verbal emotions to the basic and social visual emotion recognition. We assessed facial emotion recognition using two basic and social emotion tasks in a group of SCA patients together with a complete clinical and neuropsychological evaluation. We compared results with the performance of a control group. We demonstrated a significant difference between patients and controls both in basic and social emotion recognition, although we found a specific impairment only for social emotions. The deficit was not correlated to clinical and demographic features. The cognitive and psychological profile did not explain the impairment in emotion recognition. This result supports the hypothesis that the impairment in social emotion recognition could be specifically related to a defect in the corticocerebellar network.     

Frovatriptan versus zolmitriptan for the acute treatment of migraine with aura: a subgroup analysis of a double-blind,randomized, multicenter,Italian study

Migraine with aura affects ~20–30 % of migraineurs and it is much less common than migraine without aura. The aim of this study was to compare the efficacy of frovatriptan 2.5 mg and zolmitriptan 2.5 mg in the treatment of migraine with aura. Analysis was carried out in a subset of 18 subjects with migraine with aura (HIS criteria) out of the 107 enrolled in a multicenter, randomized, double-blind, cross-over study. According to the study design, each patient had to treat three episodes of migraine in no more than 3 months with one drug, before switching to the other treatment. The rate of pain-free episodes at 2 h was significantly (p < 0.05) larger under frovatriptan (45.8 %) than under zolmitriptan (16.7 %). Pain free at 4 h, pain relief at 2 and 4 h and recurrent episodes were similar between the two treatments, while sustained pain-free episode was significantly (p < 0.05) more frequent during frovatriptan treatment (33.3 vs. 8.3 % zolmitriptan). Our study suggests that frovatriptan is superior to zolmitriptan in the immediate treatment of patients with migraine with aura, and it is capable of maintaining its acute analgesic effect over 48 h.     

Pure topographical disorientation in a patient with right occipito-temporal lesion

We describe a patient who presented with a pure topographical disorientation after a stroke involving the right mesial occipito-temporal cortex. He could not point to external unseen landmarks or draw a map of his city, while he could recognize landmarks, and judge the distance, and describe the route between pairs of landmarks of the same city. He underwent standardized cognitive tests, and 6 tasks were used to assess a topographical orientation route-survey. This study provides evidence that topographical disorientation can be subdivided into very specific components. The results suggest that one of these components might refer to the processing of an allocentric map separable from the representation of route knowledge.     

Schwann-like adult stem cells derived from bone marrow and adipose tissue express γ-aminobutyric acid type B receptors

γ-Aminobutyric acid type B receptors (GABA-B) are expressed in glial cells of the central and peripheral nervous systems, and recent evidence has shown their importance in modulating physiological parameters of Schwann cell (SC). SC play essential roles in peripheral nerve regeneration, but several drawbacks prevent their use for nerve repair. Adult stem cells from adipose tissue (ASC) or bone marrow (BM-MSC) can be differentiated into an SC-like phenotype and used as SC replacements. The aim of this study was to investigate GABA-B receptor functional expression in differentiated stem cells by assessing the similarity to SC. By means of RT-PCR and Western blot methodologies, BM-MSC and ASC were found to express both GABA-B1 and GABA-B2 receptor subunits. The expression levels of GABA-B1b and GABA-B2 receptors were influenced by SC-like differentiation, as shown by Western blot studies. GABA-B receptor stimulation with baclofen reduced the proliferation rate of SC and differentiated ASC (dASC) but not that of dBM-MSC. In conclusion, both of the subunits that assemble into a functional GABA-B receptor are present in differentiated stem cells. Furthermore, GABA-B receptors in dASC are functionally active, regulating a key process such as proliferation. The presence of functional GABA-B receptors on differentiated stem cells opens new opportunities for a possible pharmacological modulation of their physiology and phenotype.     

Anaesthetic implications of Costello syndrome

Costello syndrome is a disorder that primarily involves ectodermal tissues and is characterized by mental and growth retardation, distinctive coarse facies, redundant skin (neck, palms and soles), and papillomata (perioral, nasal and anal). Of primary concern to anaesthesiologists are potential airway difficulties related a short neck, macroglossia, hypertrophied tonsillar and supraglottic tissues, laryngeal papillomata and choanal atresia. A significant percentage of patients also have cardiac involvement which may manifest as congenital heart defects, arrhythmias, valvular dysfunction, or hypertrophic cardiomyopathy. Central nervous system involvement includes developmental delay and seizure disorders while endocrine abnormalities have been reported including hypothalamic-pituitary dysfunction resulting in hypopituitarism, hypothyroidism, and hypoadrenalism. The authors present a 2-year old child with Costello syndrome who required anaesthesia for direct laryngoscopy, rigid bronchoscopy, bilateral pressure equalization tubes and tonsillectomy. The perioperative implications of the syndrome are discussed.