Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    The internal control of action and Parkinson's disease: a kinematic analysis of visually-guided and memory-guided prehension movements (1995)
    Springer
    Experimental brain research 105 (1995), S. 147-162 
    Details
    ISSN: 1432-1106
    Keywords: Prehension ; Reach to grasp ; Working memory ; Visual attention ; Visual feedback ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This paper reports two experiments which examined the effects of Parkinson's disease (PD) upon the sensorimotor mechanisms used to control prehension movements. Transport and grasp kinematics for visually-guided and memory-guided prehension movements were examined in healthy control subjects and compared against those of patients with idiopathic PD. Two research questions were addressed: (1) Are patients with PD particularly susceptible to distraction by non-relevant objects? (2) Are patients with PD especially reliant on external feedback when executing goal-directed actions? The results indicated that the patient group were no more susceptible to distraction by non-relevant objects than the control group. In contrast, the patients with PD were shown to be significantly, impaired when executing memory-guided reaches. Furthermore, the deficits exhibited by the PD group on memory-guided reaches were confined solely to those markers associated with the transport component of the prehension movement. That is, while both controls and patients with PD widened their grip aperture on memory-guided trials, the magnitude of this adjustment was comparable across the two groups. The implications of these findings for theories of visuomotor processing in sufferers of PD and the control of prehension movements more generally are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00242190
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Vestibular-evoked electromyographic responses in soleus: a comparison between click and galvanic stimulation (1998)
    Springer
    Experimental brain research 119 (1998), S. 504-510 
    Details
    ISSN: 1432-1106
    Keywords: Key words Clicks ; Galvanic stimulation ; Vestibular reflexes ; Vestibulospinal reflexes ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The aim of this study was to demonstrate, if possible, vestibulospinal reflex responses in soleus using a stimulus known to be capable of exciting vestibular afferents, namely 100-dB (NHL) clicks. We were able to show short-latency electromyographic (EMG) responses after clicks in five of eight normal subjects, and then we compared these responses with those after transmastoid galvanic stimulation (12 normal subjects). Stimulation of the side towards which the head was rotated (i.e. the side facing backwards) with either clicks or the cathode (anode applied to the opposite side) gave an initial excitatory response in soleus, while click or cathodal stimulation of the opposite side (i.e. the side facing forwards) gave an initial inhibitory response. Onset latencies and modulation with changes in postural task were identical for both click- and galvanic-evoked responses. In addition, there was a significant correlation between the amplitudes of the responses in soleus after click and galvanic stimulation (R 2=0.72). These similarities suggest that the earliest reflex responses in soleus after clicks and galvanic stimulation may be mediated by a common central pathway. In contrast, there was no correlation between the amplitudes of responses evoked by 100-dB clicks in soleus and those evoked by the same stimulus in the sternocleidomastoid. We conclude that vestibular activation by clicks can evoke reflex responses in lower-limb muscles and these responses have similar characteristics to the earliest responses evoked by galvanic vestibular stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050366
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Are non-relevant objects represented in working memory? The effect of non-target objects on reach and grasp kinematics (1995)
    Springer
    Experimental brain research 102 (1995), S. 519-530 
    Details
    ISSN: 1432-1106
    Keywords: Prehension ; Reach to grasp ; Working memory ; Visual attention ; Visual feedback ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The role of visual information and the precise nature of the representations used in the control of prehension movements has frequently been studied by having subjects reach for target objects in the absence of visual information. Such manipulations have often been described as preventing visual feedback; however, they also impose a working memory load not found in prehension movements with normal vision. In this study we examined the relationship between working memory and visuospatial attention using a prehension task. In this study six healthy, right-handed adult subjects reached for a wooden block under conditions of normal vision, or else with their eyes closed having first observed the placement of the target. Furthermore, the role of visuospatial attention was examined by studying the effect, on transport and grasp kinematics, of placing task-irrelevant “flanker” objects (a wooden cylinder) within the visual field on a proportion of trials. Our results clearly demonstrated that the position of flankers produced clear interference effects on both transport and grasp kinematics. Furthermore, interference effects were significantly greater when subjects reached to the remembered location of the target (i.e., with eyes closed). The finding that the position of flanker objects influences both transport and grasp components of the prehension movement is taken as support for the view that these components may not be independently computed and that subjects may prepare a coordinated movement in which both transport and grasp are specifically adapted to the task in hand. The finding that flanker effects occur primarily when reaching to the remembered location of the target object is interpreted as supporting the view that attentional processes do not work efficiently on working memory representations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00230656
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    The influence of initial hand posture on the expression of prehension parameters (1998)
    Springer
    Experimental brain research 119 (1998), S. 9-16 
    Details
    ISSN: 1432-1106
    Keywords: Key words Hand posture ; Prehension ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  This paper describes the transport and grasp kinematic parameters associated with four initial hand postures (palm flat and thumb against the hand, palm flat and thumb extended laterally, index and thumb in opposition, and index and thumb in opposition and elbow flexed 90°). A group of healthy adult subjects reached for and picked up a wooden dowel placed midsagittally, at one of three distances (20 cm, 25 cm and 30 cm). The initial posture of the hand and arm altered transport (peak velocity and peak negative acceleration) as well as grasp (peak angle and time to peak angle) parameters, particularly when the elbow was flexed 90°. The pattern of results was reproduced in a pointing paradigm. The findings are discussed in the context of joint space models of reaching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050314
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Impairment of memory and plasma flunitrazepam levels (1998)
    Springer
    Psychopharmacology 140 (1998), S. 157-163 
    Details
    ISSN: 1432-2072
    Keywords: Key words Flunitrazepam ; Psychomotor sedation ; Attention ; Working memory ; Explicit memory ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Flunitrazepam was administered to volunteers in three different oral doses. The effects on psychomotor sedation, attention, working memory and explicit memory were then assessed at various intervals after dosing and compared with levels of the drug in the plasma. Three groups of 12 healthy males with similar levels of education were given placebo or flunitrazepam (1, 2 or 4 mg) in a double-blind, random-sequence study. Volunteers completed a battery of tests at night, 3.5h after taking the drug and in the morning, 10h afterward. Blood samples were collected for drug analysis before and after the nocturnal tests and before morning tests. At night, only the highest dose of flunitrazepam (4 mg) induced significant changes in psychomotor sedation, attention, working memory, and prose immediate recall. Doses of 2 and 4 mg flunitrazepam significantly reduced the mean scores of explicit memory (morning tests). Z-scores, calculated from differences between flunitrazepam and placebo, revealed that 2 mg flunitrazepam impaired memory but not alertness or attention. Linear regression analysis of the relationship between plasma levels of flunitrazepam and its effects (Z-scores) indicated that there was a significant positive correlation between peak levels of flunitrazepam at night and impairment of night attention and explicit memory, i.e. delayed recall of prose (r =0.59, P 〈0.01) and trigrams (r =0.55, P 〈0.01). However, memory and attention Z-scores as a function of plasma levels fitted with non-linear regression analysis to the Emax model had higher correlation coefficients. To produce an effect equal to 50% of the maximum effect for memory impairment, concentrations (EC50) were 6.1 and 6.4 ng/ml for prose and trigrams delayed recall; but for attention they were much higher, at 13.2 ng/ml. The overall results indicate that higher concentrations were needed to impair attention than were required to impair memory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050753
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Reinforcing and subjective effects of morphine in human opioid abusers: effect of dose and alternative reinforcer (2000)
    Springer
    Psychopharmacology 148 (2000), S. 272-280 
    Details
    ISSN: 1432-2072
    Keywords: Key words Opioids ; Self-administration ; Progressive ratio ; Drug abuse ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Although most opioid self-administration research has been conducted with laboratory animals, such research with humans is necessary to answer questions unique to human drug-taking behavior. Objective: We investigated the influence of morphine dose and an alternative non-drug reinforcer on choice between morphine versus money and examined the relationship between drug-reinforced behavior and subjective euphoria. Methods: Five male opioid users participated in the 7-week study. During the first 5 weeks, a single dose of morphine (0, 4, 8, 16, or 32 mg/70 kg) was available each week. On Monday, subjects received an IM injection of the dose tested that week. On Tuesday, Thursday, and Friday, subjects could work for morphine or money under a second-order, progressive ratio schedule. For each primary ratio completed on the drug lever, subjects earned one-ninth of the available drug dose, and for each ratio completed on the money lever, subjects earned $1. Total amount of drug earned was administered in a single IM injection at the end of the session; money earned was credited to the subject’s account. Results: As morphine dose increased, responding for drug increased in an orderly manner and responding for money decreased. During the final phase of the study, the lowest and highest doses that maintained drug responding for each subject were repeated, and the value of the alternative reinforcer was increased to $2 per ratio. This manipulation was associated with decreased drug-maintained responding at the lowest, but not the highest, reinforcing dose of morphine. Conclusion: The progressive ratio, concurrent access procedure may be useful in predicting the outcome of drug abuse treatment interventions that use alternate reinforcement strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050051
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Human microvascular endothelial cell-extracellular matrix interaction in cellular growth state determination (1994)
    Springer
    Cell & tissue research 279 (1994), S. 37-45 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Microvascular endothelial cells ; Cell ; growth ; Extracellular matrix ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. We introduce two methods, both of which are based on cellular-extracellular matrix interaction, which will facilitate the study of human microvascular endothelial cells. One method describes the means to obtain a G1 population baseline in human microvasclular endothelial cells. Because of the contribution of the extracellular matrix in endothelial cell growth, synchronization in G1 was possible only after the incorporation of angiostatic levels of heparin and hydrocortisone into the extracellular matrix. In the second method, we demonstrate that selective perturbation of human microvascular endothelial cell-extracellular matrix interactions results in the induction of a transitional growth state, between proliferative and differentiated growth states, in human microvascular endothelial cells. In the functional, microtubule formation assays, transitional growth state endothelial cells display rates that are indermediate between those obtained from differentiated and proliferative endothelial cells. Our results demonstrate the importance of the human microvascular endothelial cell-extracellular matrix interaction in the determination of cellular growth state. Our findings also imply that responsiveness of microvascular endothelial cells to their cellular-extracellular matrix environs is highest during the differentiated growth state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050259
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Human microvascular endothelial cell-extracellular matrix interaction in cellular growth state determination (1995)
    Springer
    Cell & tissue research 279 (1995), S. 37-45 
    Details
    ISSN: 1432-0878
    Keywords: Microvascular endothelial cells ; Cell growth ; Extracellular matrix ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We introduce two methods, both of which are based on cellular-extracellular matrix interaction, which will facilitate the study of human microvascular endothelial cells. One method describes the means to obtain a G1 population baseline in human microvasclular endothelial cells. Because of the contribution of the extracellular matrix in endothelial cell growth, synchronization in G1 was possible only after the incorporation of angiostatic levels of heparin and hydrocortisone into the extracellular matrix. In the second method, we demonstrate that selective perturbation of human microvascular endothelial cell-extracellular matrix interactions results in the induction of a transitional growth state, between proliferative and differentiated growth states, in human microvascular endothelial cells. In the functional, microtubule formation assays, transitional growth state endothelial cells display rates that are indermediate between those obtained from differentiated and proliferative endothelial cells. Our results demonstrate the importance of the human microvascular endothelial cell-extracellular matrix interaction in the determination of cellular growth state. Our findings also imply that responsiveness of microvascular endothelial cells to their cellular-extracellular matrix environs is highest during the differentiated growth state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00300689
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Comparison of the intracellular pathways of immunoglobulin-G and low density lipoprotein in cultured human term trophoblast cells (1993)
    Springer
    Cell & tissue research 274 (1993), S. 619-625 
    Details
    ISSN: 1432-0878
    Keywords: Immunoglobulin G ; Low density lipoprotein (LDL) ; Cell culture ; Vesicles ; Trophoblast ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Trophoblast cells were cultured on microporous membrane filters. After incubation at different times with gold-conjugated ligands, the cells were processed for electron microscopy. Gold particles indicating the presence of both IgG and LDL appeared in a time-dependent manner in coated pits and coated vesicles. LDL-gold appeared primarily within lysosomes whereas approximately 50% of the internalized IgG-gold appeared within vesicles (diameters ranging from 35 to 80 nm) near the basal regions of the cell. These vesicles may be the protective mechanism which prevents IgG breakdown during transcytosis across trophoblast cells, thus allowing transport of the intact molecule to the fetus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314560
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...