Progressive effects of shading on experimental wetland communities over three years

To investigate how the composition of wetland communities changes over time in response to altered light regimes, experimental communities of five Carex and four grass species were subjected to artificial shading (continuous or seasonal) in a three-year field experiment. Shoot number and size was measured after six weeks, and shoot biomass was harvested five times during the experiment. Communities were initially dominated by three grass species in all treatments, but subsequently, the Carex species increased and reached dominance in the control plots, whereas grasses remained dominant in the shaded plots. Shading had no effect on the biomass of communities or of single species in the first year. In the second year, community biomass was still unaffected, but shading reduced the biomass of three Carex species and also reduced species diversity. In the third year, shading reduced community biomass and all Carex species, but not species diversity. The greater shade tolerance of the grasses could not be explained by differences in morphological plasticity: after six weeks of growth all species had increased shoot height in response to shade by 40-70%. Grasses were hardly more plastic than Carex species. We propose that the long-term success of the Carex species in full light was due to a high allocation of biomass to belowground parts, which may have reduced losses caused by repeated harvesting of shoots (a simulation of management in productive wet meadows). Shading probably caused the Carex plants to change their allocation pattern, and thus prevented their progressive increas

Neurobehavioral changes in people with post-stroke aphasia

At present, research on neurobehavioral disorders in people with post-stroke aphasia is scarce, especially in Spanish. The objective of this study is to design a new scale on neurobehavioral change, the Scale of Neurobehavioral Affectation in Aphasia (EANA, in Spanish) and to evaluate 14 people affected by chronic post-stroke aphasia (mean age: 51/ DT: 7.2) together with their main informants. At the same time, psychiatric (Neuropsychiatric Inventory, Hospital Anxiety and Depression Scale, Stroke Aphasic Depression Questionnaire), cognitive (Mini Mental State examination, Informer Test) and functional instruments (Stroke and Aphaisa Quality of Life Scale and Barthel Index) have been used to provide a multidimensional description of the affected persons. The results show statistically significant neurobehavioral changes in multiple domains. According to the EANA, those affected with post-stroke aphasia communicate with less frequently, show more introversion, shyness, dependence and apathy, behave in a more infantile manner ("makes me grimaces"), in addition to showing heightened anxiety and impulsivity. Finally, the informants report more aggressive acts, both verbal (insults) and physical (throwing objects, hitting both objects as persons), that did not occur before the stroke. According to the psychiatric instruments, many of the affected cope with anxiety, agitation and apathy, as well as mild depression. At a cognitive level, affected individuals show mild to moderate deficits, especially in working memory and temporal orientation. Functionally most individuals maintain a medium-high level of functional independence in daily activities. These findings support the inclusion of recommendations for the routine assessment and management of neurobehavioral changes to help optimize long-term recovery in people with stroke and aphasia.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Imprinted Zac1 in neural stem cells.

Neural stem cells (NSCs) and imprinted genes play an important role in brain development. On historical grounds, these two determinants have been largely studied independently of each other. Recent evidence suggests, however, that NSCs can reset select genomic imprints to prevent precocious depletion of the stem cell reservoir. Moreover, imprinted genes like the transcriptional regulator Zac1 can fine tune neuronal vs astroglial differentiation of NSCs. Zac1 binds in a sequence-specific manner to pro-neuronal and imprinted genes to confer transcriptional regulation and furthermore coregulates members of the p53-family in NSCs. At the genome scale, Zac1 is a central hub of an imprinted gene network comprising genes with an important role for NSC quiescence, proliferation and differentiation. Overall, transcriptional, epigenomic, and genomic mechanisms seem to coordinate the functional relationships of NSCs and imprinted genes from development to maturation, and possibly aging

Aphasia with anatomical isolation of the language area: A reanalysis on the light of modern neuroimaging techniques

Introduction : Goldstein (1948) and Geschwind (1968), based in data derived from anatomical post-mortem studies, postulated that the disconnection of the perisylvian language areas (PSLA) from other cortical areas was responsible for impairments in spontaneous speech and language comprehension with preservation of verbal repetition and echolalia (isolation of speech area). Nevertheless, other mechanisms (right hemisphere or bilateral hypotheses) underlying echolalic repetition have been proposed. Herein, we examined the structure and function of the PSLAs in two cases of aphasia with echolalic repetition and isolation of the left PSLA. Methods : Two patients with chronic post-stroke aphasia associated to isolation of the left PSLA were studied. Both patients underwent cognitive-language assessment and multimodal imaging. In patient 1 (p1), structural MRI, diffusion tensor imaging (DTI), functional MRI (fMRI) during repetition of words and non-words, resting state fMRI (rsfMRI) were acquired, whereas only structural MRI was performed in patient 2 (p2). The Tractotron software was used to examine the severity of disconnection in each language-related white matter tract in both patients. We quantified the severity of the disconnection by measuring the proportion of each tract that was affected. 18FDG-PET was also acquired in both patients. Results : P1 had a mixed transcortical aphasia and p2 had a transcortical sensory/anomic aphasia. In both, the MRI showed separate left anterior and posterior lesions with relative preservation of the PSLA. In both, 18FDG-PET revealed significant decrements of metabolic activity in areas of the left PSLA, although some parts showed normal metabolic activity. In p1 the left arcuate fasciculus (AF) and the inferior fronto-occipital fasciculi (IFOF) could not be reconstructed. fMRI showed perilesional activity in the left hemisphere and increased activity in the right during word repetition. rsfMRI showed compensatory activity in both hemispheres (right greater than left). Analysis with the Tractotron software revealed disconnection of both the AF and the IFOF in the left hemisphere of both patients. Discussion : Although some parts of the left PSLA had preserved metabolic activity in both patients, our neuroimaging data revealed that preserved repetition ability did not rely exclusively on the residual activity of the left PSLA. In support, the connectivity between different components of the left PSLA was severely affected. This coupled with the increased metabolic activity of the right PSLA supports the bilateral hypothesis of residual repetition in transcortical aphasias. References : Goldstein, K. (1948). Language and Language Disturbances. Geschwind, et al. (1968). Neuropsychologia 6, 327–340.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

“Need to know” and the right temporal lobe: Impaired access to semantic knowledge in acquired obsessive-compulsive disorder?

Introduction : Idiopathic obsessive-compulsive disorder (I-OCD) has been linked to abnormalities in corticostriatal circuits. Few studies have examined if the same structures are also responsible of acquired OCD (A-OCD) or if damage to anatomically-connected brain regions (e.g., temporal lobes) are also implicated in its pathogenesis. Additionally, there are some discrete obsessive-compulsive (OC) symptoms that by virtue of their presumed low occurrence and difficultly of categorization have received less attention. Amongst these, one intriguing and potentially severe type of obsessive thinking is the so-called “need to know” (NtK), a strong drive to know and obtain given information. In some patients this specific symptom, presumably resulting from impaired access to conceptual knowledge for specific verbal information (proper names, names of places), may be the principal or major feature of OCD symptomatology. We here report the cases of two male patients who developed “NtK” as the only OC symptomatology in association with malignant neoplasms involving the right temporal lobe and connected corticostriatal circuits. Methods : We used Tractotron and Disconnectome map softwares in order to identify the regions of white matter damage overlap across both patients and the proportion of damage (lesion load) of each tract of interest for each patient. We quantified the severity of the disconnection by measuring the proportion of each tract of interest to be affected by each patient´s lesion by using Tractotron software. Additionally, Positron Emission Tomography was used in order to study metabolic abnormalities. The tracts of interest were: the uncinate fasciculus, the anterior commissure, the anterior thalamic radiations, the inferior fronto-occipital fasciculus and the inferior longitudinal fasciculus. Results : There was a high overlap across brain lesions in patients 1 and 2. There was also a high overlap between areas that were affected (disconnected) due to the lesion. As expected, all the a priori selected pathways in the right hemisphere were affected since they cross the anterior part of the temporal lobe. Disconnection maps and metabolic changes in our patients suggest that the expression of OC symptoms underpinned by a semantic deficit due to right temporal damage is secondary to involvement of the uncinate fasciculus linking the temporal pole with the orbitofrontal cortex. Discussion : Data from the present study concur with previous research on A-OCD and current findings in I-OCD which suggest that the temporal lobes participate in the phenomenological expression of OCD. Also, patients with lesions in the anterior temporal lobe are prone to show a specific “Need to Know” symptoms phenomenologically similar to patients with semantic dementia in later stages. The expression of OC symptoms underpinned by a semantic deficit because of anterior right temporal lobe lesion, are due to a disconnection of the uncinate fasciculus and the orbitofrontal cortex. Further research about the neurological underpinnings of specific OCD subtypes, its evaluation and treatment, are essential. References : Berthier ML et al. Neurology. (1996) 47: 353–61. Huey E et al. J Neuropsych Clin Neurosci (2008). 20(4):390-408 Keywords : Emotions & Social Cognition; patients; single case study; adults; psychiatric; lesion mapping, behavioural.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Beneficial effects of pharmacological treatment in post-stroke dynamic aphasia: a behavioural and neuroimaging study

Introduction : Dynamic Aphasia (DA) is a rare form of language disorder characterized by reduced spontaneous speech with preservation of other language functions. Two types of DA have been described: language-specific type (type I DA) and domain-general type (type II DA). In type I DA, deficits are selective for word and sentence generation, whereas in type II DA impairments affect discourse generation, narrative, fluency, and non-verbal generation tasks. There is little information on the treatment of DA. Although treatment with a cognitive enhancing drug (bromocriptine) improved outcome in previous studies, pharmacological interventions combining two drugs acting on other neurotransmitter systems in DA have not been reported so far. Methods : We report an open-label pharmacological single case study (n = 1) in a male patient with a chronic type I/II DA secondary to an ischemic infarction in the left fronto-opercular and insular regions. After baseline evaluation, the patient received donepezil 5 mg/day (2 months), donepezil 10 mg/day (2 months), donepezil 10 mg/day plus memantine 20 mg/day (4½ months) followed by a washout period (1½ months). No speech-language therapy was used. A comprehensive cognitive and language evaluation was carried out at baseline and at different endpoints. 18FDG-PET was performed at the four timepoints. Results : Donepezil (5 mg/day) significantly improved type I DA features (normalization of verbs generation, p = 0.01), whereas donepezil (10 mg/day) improved some type II features (normalizing spontaneous speech, verbal fluency and improving generation of novel thoughts, p = 0.004), along with improvement of executive-attentional functioning. Combined therapy further enhanced cognitive function, but did not additionally improved DA. 18 FDG-PET revealed significant reductions of perilesional hypometabolic activity mainly after donepezil (10 mg/day) and washout. Discussion : Treatment with donepezil improved language deficits in a patient with chronic post-stroke type I/II DA. Combined therapy (donepezil plus memantine) further enhanced executive-attentional functioning. Beneficial changes were associated with improvements in perilesional metabolic activity. References : Luria AR et al.Acta Neurologica et Psychiatrica (1967). Robinson G et al. Brain (1998). Keywords : Language; patients; single case study; adults; cerebrovascular; behavioural, functional imaging.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Herausforderung alpiner Renaturierungen : markante Unterschiede in Vegetation, Bakterien und Boden

Die Schweiz weist mit ihrer abwechslungsreichen Topografie eine hohe Artenvielfalt auf. Die heterogene Landschaft und insbesondere die mächtigen Gebirgszüge tragen dabei zur besonderen Verantwortung gegenüber dem Schutz und Erhalt der Biodiversität bei. Bautätigkeiten und Eingriffe in die Landschaft ausserhalb der Bauzonen werden daher häufig von Renaturierungsmassnahmen begleitet. Jonathan Blank-Pachlatko untersuchte in seiner Masterarbeit am Corvatsch im Engadin, welche ökologischen Unterschiede sich dabei kurz nach der Ausführung im Vergleich zu unberührten Flächen feststellen liessen