Search results for " neurological"

The influence of eye movements on the temporal features of executed and imagined arm movements.

2007

The very close coordination between eye and hand indicates that eye movements are parts of the neural processes underlying the planning and control of arm movements. Eye movements are fundamental during observed actions and play a functional role in visual mental imagery. However, the role of eye movements during imagined actions is still unknown. Here, we report the timing features of eye and arm pointing movements for nine healthy participants in four conditions: Executed movements with orientation saccades (Eyes Free) or with no saccades (Eyes Motionless), and Imagined movements with Eyes Free or with Eyes Motionless. The first result was a facilitation effect of saccades upon both execu…

Characteristics of neuronal systems in the visual cortex

1987

The coupling complexity of cortical areas makes it very difficult to analyse them experimentally. Studies of model systems provide the possibility of adapting the analysis to the available data base and elaborating the fundamental properties that depend on the structure of the system. We propose a model system of variable complexity that is spatially two-dimensional and time-dependent, uses feedback for iteration and smoothing, includes the mapping of the cortical networks and can be nonlinear as the case requires. Combining such elementary systems on the basis of neuroanatomical findings enables us to simulate cortical mappings and to interpret neurophysiological data. The decisive factor …

An overall description of retinotopic mapping in the cat's visual cortex areas 17, 18, and 19.

1985

Mathematical functions are derived which model the retinotopic mapping in the cat's visual cortical areas 17, 18, and 19. All three mappings are simple modifications of a complex power function with an exponent of 0.43. This function is decomposed so as to give an intermediate stage which is common to all three mappings and can be regarded as a model of the lateral geniculate nucleus mapping. The influence of retinotopic mapping on visual receptive fields was studied. The results show that a dependence of the receptive field properties on the position in the visual field is to be expected.

Mathematical analysis of the stimulus for the lateral line organ

1985

Behavioral studies have shown that a blind fish is capable of detecting and recognizing stationary objects in its surroundings. It is proposed that the displacement of water caused by the fish as it moves is the basis for this detection capability. Alterations in the displacement of water around the fish, caused by the obstacle, act as stimuli for the lateral line organ. The question of how these stimuli acting on the skin of the fish, image the environment and what information is thus made available to the fish is the concern of this paper. The stimuli for the lateral line organ are derived mathematically. Two cases are treated: that of a fish gliding past an obstacle and that of one appro…

On the function of cell systems in area 18. Part I

1981

In addition to the asymmetry of the spatial coupling and of the specific temporal combination of excitation and inhibition, the non-linearity is very pronounced in area 18. Taking the sequence of a linear operation and a stationary nonlinear characteristic as a model, the experimental findings can be systematized and a cell classification specified which departs from the customary ones. The hypercomplex cell system probably originates in recurrent inhibition and leads to differentiation of the patterns along their contour line. Problems of cell classification and of the type of parallelism in the visual cortex are discussed.

Inflammatory mediators and other biomarkers in co-intoxicated patients after hyperbaric oxygen therapy (HBO2)

2016

Objective: The present study was conducted in attempt to identify reliable biomarkers in predicting the severity of neurological injury. Materials and methods: A number of 30 patients with confirmed CO poisoning and a number of 7 healthy control volunteers were involved into the study. All participants received at least 60 minutes of hyperbaric oxygen therapy (HBO2) at 2.5 atmospheres absolute (ATA). Standard blood gas analysis was performed on 10 mL venous blood samples obtained immediately before and after HBO2. Seven biomarkers and carboxyhemoglobin (COHb) levels were measured. Results: Following HBO2, all patients recovered fully and were discharged in stable condition. Significant diff…

Multi-subject fMRI analysis via combined independent component analysis and shift-invariant canonical polyadic decomposition

2014

Canonical polyadic decomposition (CPD) may face a local optimal problem when analyzing multi-subject fMRI data with inter-subject variability. Beckmann and Smith proposed a tensor PICA approach that incorporated an independence constraint to the spatial modality by combining CPD with ICA, and alleviated the problem of inter-subject spatial map (SM) variability.This study extends tensor PICA to incorporate additional inter-subject time course (TC) variability and to connect CPD and ICA in a new way. Assuming multiple subjects share common TCs but with different time delays, we accommodate subject-dependent TC delays into the CP model based on the idea of shift-invariant CP (SCP). We use ICA …

The Tachykinin Neuroimmune Connection in Inflammatory Pain

1991

Modelling the insect Mushroom Bodies: Application to sequence learning

2015

Learning and reproducing temporal sequences is a fundamental ability used by living beings to adapt behaviour repertoire to environmental constraints. This paper is focused on the description of a model based on spiking neurons, able to learn and autonomously generate a sequence of events. The neural architecture is inspired by the insect Mushroom Bodies (MBs) that are a crucial centre for multimodal sensory integration and behaviour modulation. The sequence learning capability coexists, within the insect brain computational model, with all the other features already addressed like attention, expectation, learning classification and others. This is a clear example that a unique neural struc…

A Dichoptic Edge Effect Resulting from Binocular Contour Dominance

1980

If one eye sees a bright field on a dark surround while a homogeneous background is presented to the other eye, then a distinct dark zone appears at the outer borders of the field.If the surround is coloured, then the zone is of corresponding hue. The effect disappears if the edge of the field can be fused with a bar of appropriate contrast. The influence of parameters such as pattern contrast and size were studied quantitatively. A model is proposed relating the effect to receptive-field organisation and the fusion process.