spatial pattern Dotaz Zobrazit nápovědu
BACKGROUND: Severe canopy-removing disturbances are native to many temperate forests and radically alter stand structure, but biotic legacies (surviving elements or patterns) can lend continuity to ecosystem function after such events. Poorly understood is the degree to which the structural complexity of an old-growth forest carries over to the next stand. We asked how pre-disturbance spatial pattern acts as a legacy to influence post-disturbance stand structure, and how this legacy influences the structural diversity within the early-seral stand. METHODS: Two stem-mapped one-hectare forest plots in the Czech Republic experienced a severe bark beetle outbreak, thus providing before-and-after data on spatial patterns in live and dead trees, crown projections, down logs, and herb cover. RESULTS: Post-disturbance stands were dominated by an advanced regeneration layer present before the disturbance. Both major species, Norway spruce (Picea abies) and rowan (Sorbus aucuparia), were strongly self-aggregated and also clustered to former canopy trees, pre-disturbance snags, stumps and logs, suggesting positive overstory to understory neighbourhood effects. Thus, although the disturbance dramatically reduced the stand's height profile with ~100% mortality of the canopy layer, the spatial structure of post-disturbance stands still closely reflected the pre-disturbance structure. The former upper tree layer influenced advanced regeneration through microsite and light limitation. Under formerly dense canopies, regeneration density was high but relatively homogeneous in height; while in former small gaps with greater herb cover, regeneration density was lower but with greater heterogeneity in heights. CONCLUSION: These findings suggest that pre-disturbance spatial patterns of forests can persist through severe canopy-removing disturbance, and determine the spatial structure of the succeeding stand. Such patterns constitute a subtle but key legacy effect, promoting structural complexity in early-seral forests as well as variable successional pathways and rates. This influence suggests a continuity in spatial ecosystem structure that may well persist through multiple forest generations.
Animals demonstrate their ability to represent a geometric configuration of their environment and to use this information for spatial decisions in their response space in many situations. In presented experiment, we examined the ability of rats to interpret a configuration of abstract visual stimuli to make spatial decisions in a real response space. We tested whether they are able to interpret spatial configuration of abstract stimuli or whether they perceive such visual stimuli simply as geometric patterns associated to particular spatial choices. The rats were tested in a Skinner box with four nosing holes in the transparent front wall through which a computer screen was visible. According to the visual stimuli on the screen, the rats should choose the appropriate nosing hole to obtain a reward. We compared two groups of rats: the first group was exposed to the visual stimuli designed as a representation of the response space: the position of rewarded nosing hole was shown in relation to other nosing holes. The second group was exposed to one of four geometric patterns associated to one of the four nosing holes but without any implicit information about the response space. The results suggested that rats using the stimuli with information about configuration were significantly more successful than rats trained to respond to visual stimuli unrelated to the geometry of the environment.
- MeSH
- diskriminační učení fyziologie MeSH
- financování organizované MeSH
- krysa rodu rattus MeSH
- pochopení fyziologie MeSH
- potkani Long-Evans MeSH
- prostorové chování fyziologie MeSH
- rozpoznávání obrazu fyziologie MeSH
- výběrové chování fyziologie MeSH
- zraková percepce MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
BACKGROUND: The hippocampus, entorhinal cortex, and basal forebrain are among the first brain structures affected by Alzheimer's disease (AD). They play an essential role in spatial pattern separation, a process critical for accurate encoding of similar spatial information. OBJECTIVE: Our aim was to examine spatial pattern separation and its association with volumetric changes of the hippocampus, entorhinal cortex, and basal forebrain nuclei projecting to the hippocampus (the medial septal nuclei and vertical limb of the diagonal band of Broca - Ch1-2 nuclei) in the biomarker-defined early clinical stages of AD. METHODS: A total of 98 older adults were recruited from the Czech Brain Aging Study cohort. The participants with amnestic mild cognitive impairment (aMCI) due to AD (n = 44), mild AD dementia (n = 31), and cognitively normal older adults (CN; n = 23) underwent spatial pattern separation testing, comprehensive cognitive assessment, and MRI brain volumetry. RESULTS: Spatial pattern separation accuracy was lower in the early clinical stages of AD compared to the CN group (p < 0.001) and decreased with disease severity (CN > aMCI due to AD > AD dementia). Controlling for general memory and cognitive performance, demographic characteristics and psychological factors did not change the results. Hippocampal and Ch1-2 volumes were directly associated with spatial pattern separation performance while the entorhinal cortex operated on pattern separation indirectly through the hippocampus. CONCLUSION: Smaller volumes of the hippocampus, entorhinal cortex, and basal forebrain Ch1-2 nuclei are linked to spatial pattern separation impairment in biomarker-defined early clinical AD and may contribute to AD-related spatial memory deficits.
- MeSH
- Alzheimerova nemoc diagnostické zobrazování psychologie MeSH
- kognitivní dysfunkce diagnostické zobrazování psychologie MeSH
- kohortové studie MeSH
- lidé středního věku MeSH
- lidé MeSH
- magnetická rezonanční tomografie trendy MeSH
- mozek diagnostické zobrazování fyziologie MeSH
- průřezové studie MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- stárnutí fyziologie MeSH
- světelná stimulace metody MeSH
- vnímání prostoru fyziologie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Česká republika MeSH
Cíl Cílem předkládané práce je zjistit, jakým způsobem je postižena prostorová paměť u pacientů s Alzheimerovou chorobou a zda je postižena i u pacientů s Mírnou kognitivní poruchou. Je zde srovnáván kvalitativní charakter tohoto postiže¬ ní. Soubor a metodika. Vyšetřili jsme prostorovou paměť u 15 dobrovolníků a 42 pacientů, kteří byh vyšetřeni standardním protokolem a rozděleni podle klinických kritérií a výsledku neuropsychologického vyšetření do čtyř skupin: Alzheimerova choroba (ACH), Subjektivní poruchy paměti (SPP), neamnestická Mírná kognitivní porucha (naMCI) a amnestická Mírná kognitivní porucha (aMCI). Prostorová kognice byla vyšetřena Testem skrytého cíle (HGT), který srovnává deficit prostorové paměti ve dvou rozdílných složkách - egocentrické a alocentrické. Reálná verze testu byla prováděna v experimentálním stanu Blue Velvet Arena (BVA) a virtuální verze, která je mapovou analogií reálné verze, byla prováděna na osobním počítači (PC). Výsledky. U pacientů s ACH jsme zjistili v reálné i virtuální verzi testu poruchu v egocentrické a alocentrické složce prostorové paměti (p<0,01). U pacientů s aMCI bylo v obou verzích testu přítomno kvalita¬ tivné stejné, jen kvantitativně méně vyjádřené postižení v egocentrické (p<0,01) a alocentrické (p<0,05) složce prostorové paměti. Pacienti s naMCI selhávali v přechodu z egocentrické na alocentrickou fázi ve virtuální verzi testu (p<0,05). Pacienti se SPP nebyli postiženi ani v jedné ze složek prostorové paměti. Závěry. Vyšetření prostorové kognice může být podkladem pro klasifikaci pacientů do skupin: ACH, aMCI, naMCI a SPP. Prokázali jsme, že v případě ACH a aMCI se jedná o kontinuum kvantitativně různě vyjádřeného deficitu stejné kvality.
Objective. The aim was to investigate the pattern of spatial memory impairment in patients with Alzheimer's disease, and to find whether or not the spatial memory is impaired in patients with Mild Cognitive Impairment. The qualitative and quantitative characters of impairment were compared. Subjects and Methods. Spatial memory was examined in 15 healthy volunteers and 42 patients, who had undergone a standard diagnostic procedure. These patients were subsequently classified according to clinical criteria and neuropsychological testing into four groups: Alzheimer's disease (AD), Subjective memory complaints (SMC), nonamnestic Mild Cognitive Impairment (naMCI) and amnestie Mild Cognitive Impairment (aMCI). The Hidden Goal Task test was used to examine spatial memory. This test compares two types of spatial memory - egocentric and allocentric. A real version of the test was performed in an experimental tent Blue Velvet Arena (BVA), while a virtual version, which is the map analogy of the real version, was carried out on a personal computer (PC). Results. There was found an impairment in both egocentric and allocentric spatial memory (p<0.01) in patients with AD in the real as well as virtual versions of the test. Qualitatively similar, but quantitatively less profound impairment in egocentric (p<0.01) and allocentric (p<0.05) parts of spatial memory in both versions of the test was presented in patients with aMCI. Patients with naMCI were impaired in the transition from egocentric to allocentric virtual phase of the test (p<0.05). Subjects with SMC were not impaired in any part of spatial memory. Conclusions. The spatial memory examination can be used as the basis for patients' classification into the following groups: AD, aMCI, naMCI a SMC. Our experiments have proved that in the case of AD and aMCI it is a continuity of the same quality impairment but with quantitatively different expression.
[Economic pattern of life of the stationary population]
Alzheimerova choroba (AD) je od svého počátku spojena s poruchou prostorové navigace. Vyvíjí se pravděpodobně několik let před klinickými projevy. Klinicky se AD projevuje nejdříve kognitivními poruchami bez omezení běžného života pacienta. Toto stádium se nazývá mírná kognitivní porucha (MCI) a rozlišení toho, jaký vzorec kognitivního postižení se váže s pozdějším vznikem AD, je důležitým cílem současného výzkumu. V tomto článku informujeme o našich experimentech týkajících se prostorové navigace u MCI. Test skrytého cíle vyvinutý v naší laboratoři je analogií Morrisova vodního bludiště a hodnotí dva typy navigace: alocentrickou, používající vzdálené orientační body, a egocentrickou, používající současnou polohu subjektu. Pacienti s amnestickou MCI se zdají být v tomto testu postiženi a vzorec jejich postižení v jednotlivých subtestech je závislý na typu MCI. Vyšetření prostorové navigace může být užitečné pro dlouhodobé sledování vývoje choroby a hodnocení rizika vývoje AD u presymptomatických pacientů.
Alzheimer's disease (AD) is from its start associated with spatial disorientation. The disease probably develops in the brain s everal years before clinical manifestation. Clinically, it starts by cognitive impairment without any restriction of the daily life of the patients. This stage is called mild cognitive impairment (MCI), and distinction of which pattern of cognitive impairment is connected wi th later development of the Alzheimer's disease is an important objective for current medicine. In this article we report about our expe riments concerning spatial navigation in MCI. Hidden Goal Task developed in our lab is a real space analogue of Morris water maze and e valuates two modes of spatial navigation: allocentric, using distal orientation cues, and egocentric, using current subject position. Am nestic MCI patients seem to be impaired in this test and the pattern of their impairment in individual subtests is dependent on the type o f MCI. Spatial navigation assessment can be useful for longitudinal monitoring of the disease progression or evaluation of pre-symptom atic individuals at risk of AD.
- MeSH
- Alzheimerova nemoc komplikace psychologie MeSH
- bludiště - učení fyziologie MeSH
- finanční podpora výzkumu jako téma MeSH
- financování organizované MeSH
- hipokampus fyziologie MeSH
- kognitivní poruchy etiologie psychologie MeSH
- lidé MeSH
- neurokognitivní poruchy etiologie komplikace psychologie MeSH
- orientace fyziologie MeSH
- prostorové chování fyziologie MeSH
- psychologické testy normy statistika a číselné údaje MeSH
- Check Tag
- lidé MeSH
