References of "Experimental Brain Research"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailVisual neglect: Is there a relationship between impaired spatial working memory and re-cancellation?
Wansard, Murielle ULg; Meulemans, Thierry ULg; Gillet, Sophie ULg et al

in Experimental Brain Research (2014)

In visual search tasks, neglect patients tend to explore and repeatedly re-cancel stimuli on the ipsilesional side, as if they did not realize that they had previously examined the rightward locations ... [more ▼]

In visual search tasks, neglect patients tend to explore and repeatedly re-cancel stimuli on the ipsilesional side, as if they did not realize that they had previously examined the rightward locations favoured by their lateral bias. The aim of this study was to explore the hypothesis that a spatial working memory deficit explains these ipsilesional re-cancellation errors in neglect patients. For the first time, we evaluated spatial working memory and re-cancellation through separate and independent tasks in a group of patients with right hemisphere damage and a diagnosis of left neglect. Results showed impaired spatial working memory in neglect patients. Compared to the control group, neglect patients cancelled fewer targets and made more re-cancellations both on the left side and on the right side. The spatial working memory deficit appears to be related to re-cancellations, but only for some neglect patients. Alternative interpretations of re-exploration of space are discussed. [less ▲]

Detailed reference viewed: 24 (4 ULg)
Full Text
Peer Reviewed
See detailTMS of the occipital cortex induces tactile sensations in the fingers of blind Braille readers
Ptito, M.; Fumal, Arnaud ULg; Maertens De Noordhout, Alain ULg et al

in Experimental Brain Research (2008), 184(2), 193-200

Various non-visual inputs produce cross-modal responses in the visual cortex of early blind subjects. In order to determine the qualitative experience associated with these occipital activations, we ... [more ▼]

Various non-visual inputs produce cross-modal responses in the visual cortex of early blind subjects. In order to determine the qualitative experience associated with these occipital activations, we systematically stimulated the entire occipital cortex using single pulse transcranial magnetic stimulation (TMS) in early blind subjects and in blindfolded seeing controls. Whereas blindfolded seeing controls reported only phosphenes following occipital cortex stimulation, some of the blind subjects reported tactile sensations in the fingers that were somatotopically organized onto the visual cortex. The number of cortical sites inducing tactile sensations appeared to be related to the number of hours of Braille reading per day, Braille reading speed and dexterity. These data, taken in conjunction with previous anatomical, behavioural and functional imaging results, suggest the presence of a polysynaptic cortical pathway between the somatosensory cortex and the visual cortex in early blind subjects. These results also add new evidence that the activity of the occipital lobe in the blind takes its qualitative expression from the character of its new input source, therefore supporting the cortical deference hypothesis. [less ▲]

Detailed reference viewed: 30 (0 ULg)
Full Text
Peer Reviewed
See detailEffects of repetitive transcranial magnetic stimulation on visual evoked potentials: new insights in healthy subjects
Fumal, Arnaud ULg; Bohotin, V.; Vandenheede, Michel et al

in Experimental Brain Research (2003), 150(3), 332-340

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its ... [more ▼]

In a previous comparative study with migraineurs, we found in 24 normal subjects that the amplitude of the pattern-reversal visual evoked potential (PR-VEP) in the first block of 100 responses and its habituation over 6 sequential blocks were significantly decreased after 1 Hz repetitive transcranial magnetic stimulation (rTMS), while 10 Hz rTMS had no significant effect. We report here our results on the reproducibility of the rTMS effect studied in ten of these subjects by repeating the recordings for each frequency three times on different days. We have also reanalysed the data obtained in 24 normal subjects, looking separately at the results in those stimulated at an intensity equal to phosphene threshold (group 1; n=14) and those stimulated at 110% of motor threshold because of unelicitable phosphenes (group 2; n=10). We finally determined the precise duration of the rTMS effect. Despite some interindividual variability, the effects of both rTMS frequencies on first block amplitude, habituation between first and sixth block and habituation slope over the six blocks were highly reproducible. The only difference between the two groups of subjects was the effect of 1 Hz rTMS on the second measured PR-VEP component. Whereas first block amplitude of the first P1-N1 component and habituation were decreased in both groups, such a decrease was found for the second P1-N2 component only in group 1 stimulated at phosphene threshold. The dishabituation of the N1-P1 component after 1 Hz rTMS was maximal at 15 min, but lasted up to 33 min, while that of P1-N2 disappeared after 3 min. There was a non-significant trend ( p=0.06) for a reduction of first block amplitude after 10 Hz rTMS in the total group of subjects, but no effect on habituation. The inhibitory effect of 1 Hz rTMS, which reduces in healthy controls both first block PR-VEP amplitude and habituation, probably by decreasing the preactivation excitability level of the underlying visual cortex, is thus reproducible and long lasting. Long trains of 10 Hz rTMS tend to attenuate reproducibly the cortical preactivation level in normal subjects, but they do not affect habituation at all, which contrasts with their effect in migraineurs, in whom, as previously reported, they significantly correct the habituation deficit. The absence of an effect of 1 Hz rTMS on PR-VEP P1-N2 in subjects stimulated at 110% of motor threshold may be explained by the deeper anatomical location of the cortical generators of this component and the lower stimulation intensity used. Taken together our results confirm that the effect of rTMS on the underlying cortex depends on several variables such as frequency, intensity and level of cortical preactivation. [less ▲]

Detailed reference viewed: 6 (0 ULg)
Full Text
Peer Reviewed
See detailActivation of the supplementary motor area and of attentional networks during temporal processing
Macar, F.; Lejeune, Helga ULg; Kirsch, Murielle ULg et al

in Experimental Brain Research (2002), 142(4), 475-485

This paper first provides a survey of the expanding brain imaging literature in the field of time processing. showing that particular task features (discrete vs rhythmic, perceptual vs motor) do not ... [more ▼]

This paper first provides a survey of the expanding brain imaging literature in the field of time processing. showing that particular task features (discrete vs rhythmic, perceptual vs motor) do not significantly affect the basic pattern of activation observed. Next, positron emission tomography (PET) data obtained in a timing task (temporal reproduction) with two distinct duration ranges (2.2-3.2 and 9-13 s) are reported. The stimuli consisted of vibrations applied to the subject's right middle finger. When the vibration ended, the subject estimated an interval identical to its length before pressing a response button. The control task used cued responses with comparable intervals and stimuli, The pattern of activation obtained in the timing task as compared to control mainly included areas having attentional functions (the right dorsolateral prefrontal, inferior parietal, and anterior cingulate cortices), and the supplementary motor area (SMA). No significant difference was seen as a function of the duration range. It is argued, firstly. that involvement of the attentional areas derives from specific relations between attention and the temporal accumulator, as described by dominant timing models. and, secondly, that the SMA, or more probably one of its subregions, subserves time processing [less ▲]

Detailed reference viewed: 32 (1 ULg)
Full Text
Peer Reviewed
See detailHistochemical study of cobalt-induced focal epilepsy
Brotchi, Jacques; Scuvée-Moreau, Jacqueline ULg; Dresse, Albert ULg et al

in Experimental Brain Research (1978), 32

Detailed reference viewed: 8 (2 ULg)
See detailNew contributions to the analysis of conditioned temporal regulations in animals
Lejeune, Helga ULg; Blondin, Christiane ULg; Mantanus, H. et al

in Experimental Brain Research (1975), 23

Detailed reference viewed: 17 (2 ULg)