Biomedical subjects

Eric Siéroff

Publications and source records attributed to Eric Siéroff.

9 recordsLinked to original sources

PubMed2006

The phenomenology of endogenous orienting.

Can we build endogenous expectations about the locus of occurrence of a target without being able to describe them? Participants performed cue-target detection tasks with different proportions of valid and invalid trials, without being informed of these proportions, and demonstrated typical endogenous effects. About half were subsequently able to correctly describe the cue-target relationships ('verbalizers'). However, even non-verbalizer participants showed endogenous orienting with peripheral cues (Experiments 1 and 3), not depending solely on practice (Experiment 2). Explicit instructions did not bring about dramatic advantages in performance (Experiment 4). With central symbolic cues, only verbalizers showed reliable endogenous effects (Experiment 5). We concluded that endogenous orienting with peripheral cues can occur independently of participants developing explicit hypotheses about the cue-target relationships.

Adult↗

PubMed2005

Deficit of preparatory attention in children with frontal lobe epilepsy.

We compared the performance of a sustained attention task by children with epilepsy in either the frontal or temporal lobe. In a new simple task that specifically measures preparatory attention, developed recently by LaBerge, Auclair, and Siéroff [LaBerge, D., Auclair, L., & Siéroff, E. (2000). Preparatory attention: Experiment and theory. Consciousness and Cognition, 9, 396-434], patients responded to a target presented in the centre of the display and ignored a distracter presented at locations to the right or the left side of the target. The distracter was presented prior to the onset of the target and the relative frequency of the distracter to target was varied within a block of trials (from 0% to 67%). Children with frontal lobe epilepsy showed a higher mean slope of response time to the target as a function of distracter probability compared to children with temporal lobe epilepsy or compared to the response time slope of control subjects. The response time slope of children with temporal lobe epilepsy did not differ from that of control subjects. These results indicate that the presence of frontal lobe epilepsy selectively affects the capacity of these patients to resist the interference a distracter.

Adolescent↗

PubMed2004

Independent effects of endogenous and exogenous spatial cueing: inhibition of return at endogenously attended target locations.

Inhibition of return (IOR) is thought to reflect a bias against returning attention to previously attended locations. According to this view, IOR should occur only if attention is withdrawn from the target location prior to target appearance. In the present study, endogenous attention and exogenous cueing were manipulated orthogonally. IOR was observed both when a target appeared at an unexpected location, and when a target appeared at the expected location. A similar pattern of results was obtained in a reanalysis of data from a study with Neglect patients. These results suggest that IOR is independent of endogenous orienting.

Adult↗

PubMed2004

Deficit of preparatory attention in frontotemporal dementia.

We studied preparatory attention in patients suffering from frontotemporal dementia in the beginning stages of the disease, using an experimental test developed by LaBerge, Auclair, and Siéroff (2000). In this experimental test, a distracter can appear while subjects have to prepare to respond to a simple target. The probability that a distracter can appear in a trial is varied across three blocks. Normal controls show an increase of response times to targets (slope) as a function of the distracter probability, preparatory attention to the target is reduced by the increase of the distracter probability. Patients suffering from frontotemporal dementia show a slope of response times which is more than twice as large as the slope obtained by their matched controls. Such an abnormal increase of response times to targets is interpreted as a deficit in preparatory attention. Patients also show more omissions than controls. We suggest that this deficit in preparatory attention is related to the frontal lesion presented by the patients and can result in higher distractibility, a symptom frequently encountered in these patients.

Aged↗

PubMed2004

Neglected attention in apparent spatial compression.

Halligan and Marshall [Cortex 27 (1991) 623] devised a new test to evaluate the hypothesis that in visual neglect, left space is systematically compressed rightwards. In the critical condition of the original study, rows of horizontally arranged numbers with a target arrow pointing to one of them from the opposite margin of the display were presented. When asked to verbally identify the number indicated by the arrow, a right brain-damaged patient with left neglect and hemianopia often indicated a number to the right of the target. The more the target was located on the left, the greater the response shift rightward, as if rightward compression were linearly proportional to the co-ordinates of Euclidian space. However, a possible alternative account could be that the patient's attention was attracted by the numbers located to the right of the target digit, thus biasing her responses toward numbers on the right. To explore this hypothesis, we asked normal participants and patients with right hemisphere lesions, with and without neglect or hemianopia, to mark on the margin of a sheet the approximate location indicated by an arrow situated on the opposite margin. In three different conditions, the arrow indicated either one of several numbers or lines in a row, or a blank location on the sheet margin. Only patients with left neglect, and especially those with associated hemianopia, deviated rightward, and then crucially only on those conditions where visible targets were present, consistent with the attentional bias account.

Adult↗

PubMed2004

[Planning and activities of daily living in Alzheimer's disease and frontotemporal dementia].

OBJECTIVE: To study the relationship between the disturbances in activities of daily living and the scores on tests assessing planning activities in frontotemporal dementia (FTD) and Alzheimer's disease (AD). METHODS: Eleven patients with FTD were compared to 11 patients with AD and 29 healthy controls. Cognitive status, evaluated by the Dementia Rating Scale (DRS) and the Mini Mental State Examination (MMSE) was identical in the two groups of patients. Activities of daily living were assessed by three questionnaires completed by the main caregiver: (1) the Cognitive Difficulties Scale (CDS); (2) the NADL, a composite scale including the Physical self-maintenance scale (ADL) the Instrumental activities of daily living (IADL) the social activities scale, (SADL); (3) the Dysexecutive Questionnaire (DEX) from the Behavioural Assessment of the Dysexecutive Syndrome. Planning abilities were assessed by the tower of London and three tests from the BADS: the key search, the zoo map and the six elements. RESULTS: No quantitative differences were found between FTD and AD patients in daily living activities disturbances or scores on planning tests. Both were closely related to the global cognitive performance assessed by the DRS or the MMSE but no clear relationship was found between them. The scores on the tower of London were not correlated to those on the tests from the BADS. CONCLUSION: Neither assessment of activities of daily living or scores on the planning tests could differentiate FTD from AD. Planning appears as a multidimensional construct poorly assessed by the usual assessment tools.

Activities of Daily Living↗

PubMed2004

[Attention and aging].

Due to progress in the cognitive theories in the last twenty years, the description of attentional deficits associated with normal or pathological aging has substantially improved. In this article, attentional deficits are presented according to Posner theory, which describes three sub-systems in a global network of attention: vigilance, selective attention, command. This theory not only characterizes the functions of these subsystems, but gives precise indications about their anatomical and neurochemical substrates. Several clinical tests can be described for each of these different subsystems. The main attentional deficits are presented in the second part of this paper: if some decline of the attentional command occurs in normal aging, a real deficit in this subsystem is found in most degenerative processes (frontotemporal dementia, Alzheimer and Parkinson diseases). Alzheimer disease is also frequently associated with a deficit of selective spatial attention, early in the evolution of the disease.

Age Factors↗

PubMed2002

Attentional cueing effect in the identification of words and pseudowords of different length.

Three experiments studied the influence of spatial attention on familiar and unfamiliar letter string identification. Siéroff and Posner's (1988) cueing procedure was used: A cue indicated in advance either the beginning (left) or the end (right) of a foveally presented letter string that participants were instructed to read aloud. Results showed that the precue had a stronger influence on pseudoword than on word identification. Similar results were obtained when participants were instructed to report the identity of the cue or not. For pseudowords, a cueing effect was obtained regardless of length (6, 8, and 10 letters), whereas only 10-letter words showed such an effect, though to a lesser degree than pseudowords of the same length. However, results showed that shorter words were also influenced by the cue location when the exposure duration was reduced. Results are compatible with an early role of spatial attention in letter string processing, but they also suggest that the lexical status of a letter string can directly influence the distribution of attention before the identification process is completely achieved. Although orienting of spatial attention seems heavily involved in a pseudoword identification, some spatial attention mechanism could also take place in the case of familiar words. The results are discussed within two theoretical frameworks concerning the involvement of spatial attention in word identification: The "replacement" theory and the "redistribution" theory.

Adolescent↗

PubMedDate not supplied

Conditions of visual verbal extinction: does the ipsilesional stimulus have to be identified?

Six left-neglect patients were presented with four-letter words in the left and/or right hemifield, in different contextual conditions: unilateral, bilateral-x in which one word appears on one side and a string of "x" appears on the other side (the side of "x'' was not predictable), and bilateral-word (presentation of one word in each hemifield). In Experiment 1, left extinction occurred even if the right stimulus was an easily discriminable string of "x." Experiment 2 showed that increasing the size of the left stimuli reduced extinction when a string of "x" was presented on the right hemifield. However, extinction was stronger with bilateral-word presentation. These results indicate the presence of an early component in the extinction phenomenon, i.e., a "magnetic" attraction toward the ipsilesional hemifield, but are also in favor of some additional deficit, at a later stage of information processing.

Brain↗