Frontal Tasks Research Articles

Are semantic and letter fluency tasks temporal and frontal tasks?

Are semantic and letter fluency tasks temporal and frontal tasks?

A test of the frontal‐specificity hypothesis in the cognitive performance of adults with phenylketonuria

Twenty‐two adults with phenylketonuria and 22 control participants matched for age, sex, and intelligence, performed three tasks known to be sensitive to the effects of frontal‐lobe dysfunction, and three tasks sensitive to the effects of more posterior lesions. The most robust group differences were obtained with the frontal tasks, although sortie differences were also detected with the posterior tasks. In the participants with phenylketonuria, performance on the frontal tasks, but not the posterior tasks, was related to degree of phenylalanine elevation. The results are discussed in terms of the theory of dopamine depletion, frontal‐lobe dysfunction, and cognitive performance in phenylketonuria.

Neuropsychological Investigation of Anterior and Posterior Cortical Function in Early-Stage Probable Alzheimer’s Disease

In vivo neuroimaging studies have generally indicated a greater involvement of posterior cortical areas in early-stage dementia of the Alzheimer type (DAT) relative to frontal involvement. By contrast, some recent neuropsychological studies have shown that DAT patients perform poorly in frontal lobe tasks even in the early stages of the disease, although there is disagreement as to whether this necessarily implicates frontal pathology. The main aim of this study was to examine the hypothesis prompted by both neuroimaging studies and the traditional clinical conception of the disease, that, compared with the functioning of posterior association cortex, executive functions (thought to depend on frontal lobe integrity) are relatively spared in the early stages of DAT. A group of patients with a diagnosis of early-stage, probable DAT (n= 17) was compared with age- and IQ-matched controls (n= 17) across a range of neuropsychological tasks presumed to exercise frontal or temporoparietal functions. A profile of strengths and weaknesses was observed across ‘anterior’ and ‘posterior’ cognitive tests, including dissociations among some tests of temporoparietal function, in particular visual object perception (impaired) and spatial analysis skills (intact). Thus there was little support for the notion that the disease progresses cortically in a posterior-to-anterior direction. Possible reasons for the discrepancy between neurophysiological and neuropsychological observations are discussed, including the possibility that neuropsychological tests do not provide a valid indication of regional brain function when used in the context of DAT. Caution is urged in the clinical application of ‘frontal lobe tests’ for the differential diagnosis of DAT.

Anosognosia, intrusions and ‘frontal’ functions in Alzheimer's disease and depression

The relationship between anosognosia of memory deficit, intrusions and ‘frontal’ functions was investigated in 12 Alzheimer (DAT) patients, 12 depressed patients and 24 normal controls. DAT and depressed patients could not be dissociated according to the proportion of intrusion they produced in memory tasks. However, regardless of their clinical diagnosis, patients with anosognosia produced significantly more intrusions than patients without anosognosia, and anosognosia of memory deficit was positively and strongly correlated to the tendency to produce intrusions. By contrast, there was no correlation between intrusions, anosognosia and patients' performance on frontal tasks except for Verbal Fluency. Whereas anosognosia of memory deficit seems indispensable for intrusions, frontal dysfunction must not be considered a necessary condition for intrusions or anosognosia.

Long-term neuropsychologic sequelae of childhood leukemia: Comparison of two CNS prophylactic regimens

To compare the late neuropsychologic toxicities of CNS prophylaxis in childhood acute lymphoblastic leukemia (ALL), a transversal assessment was performed in two groups of ALL patients and two control groups. The ALL patients had received one of the following CNS prophylaxes: cranial irradiation, 24 Gy and i.t. MTX 10 mg/m2, 6 doses (RT group, n = 25) or i.t. Ara-C 30 mg/m2 and i.t. MTX 10 mg/m2, 10 doses (ChT group, n = 29). The two control groups were: Siblings (Sb, n = 24) and Solid Tumors (ST, n = 22). Intelligence Quotient (IQ), memory, learning, attention and frontal tasks were studied. Comparative analyses between ChT and RT showed no differences in any of the tests. When RT was compared with ST or Sb, RT showed a 10-point lower mean IQ ( p > 0.05). The results of ChT versus ST or versus Sb were worse in the ChT group. In many tests the differences were statistically significant. Analyses of the 54 ALL patients compared with the 46 controls showed significant differences in all tests except verbal memory and verbal learning. Neuropsychological sequelae of CNS prophylaxis are discussed, and in particular, the role of cranial radiotherapy and i.t. Ara-C. We conclude that prophylactic CNS therapy may cause cognitive dysfunctions.

A neuropsychological investigation into frontal lobe involvement in dementia of the Alzheimer type.

Studied frontal lobe involvement in dementia of the Alzheimer type (DAT) using 4 neuropsychological tests (verbal fluency, delayed alternation, subject-ordered pointing, and the Wisconsin Card Sorting Test) in 25 patients suffering from DAT and 12 age-matched normal controls. The first 3 tasks demonstrated that a frontal lobe impairment is present at all stages of the disease and is related to disease severity. Results offer information regarding the frontal component in DAT by providing neuropsychological support for the findings of an anterior pathology as reflected in blood flow and metabolism studies. The need for suitable frontal tasks with minimal memory involvement in the study of dementia is emphasized, and the delayed alternation task is recommended.

Smooth pursuit eye tracking and neuro-psychological performance in healthy volunteers. Exploring a possible genetic marker for vulnerability to schizophrenia.

Eye movement dysfunction (EMD) has been repeatedly found in schizophrenics and their first-degree relatives. In the present study, smooth pursuit eye tracking was measured in healthy subjects and related to performance on computerized neuropsychological tasks assumed to involve frontal or frontoparietal functions: monitoring perspective fluctuations (Necker cube), finger tapping, trail making, reaction time (RT) and a perceptual maze test. Poor trackers performed worse on tasks requiring parallel processing (trail making with letters and digits and RT with random auditory signals for response inhibition) and made more errors and cancellations on the mazes. Results are in line with our earlier EMD results on schizophrenics, showing poor performance on frontal tasks. However, their deficiency was more pervasive, whereas the present healthy EMD subjects only had difficulties with more complex tasks. The results are of interest in view of the recent evidence that EMD may be a genetic marker for vulnerability to schizophrenia.

Effects of the D-1 agonist SKF-38393, combined with haloperidol, in schizophrenic patients: A preliminary report

see if its agonist effects would stimulate prefrontal areas that might be dense in D1 receptors and lead to improvement in specific frontal tasks. Chronic schizophrenic patients were administered haloperidol plus placebo and haloperidol plus SKF 38393 in a double-blind crossover. Patients were examined with a highly specific prefrontal task, the WCST, and a control task, a digit span distraction task. Preliminary data from four subjects suggested that three out of four of them manifested an improvement on the WCST with SKP 38393, with that improvement reversing after discontinuation in two. Digit span distraction task performance was unrelated to Di agonist condition. By the time of presentation 12 subjects will be completed in the protocol and clearer interpretation will be possible.

Comparing frontal and lateral viewing in the pigeon. I. Tachistoscopic visual acuity as a function of distance

Pigeon's visual acuity has mainly been tested in free viewing conditions so that the direction of gaze could not be controlled. In order to be able to compare the resolving power of the two retinal areas of higher cellular density - the area dorsalis in the red field with frontal binocular projection and the fovea centralis with lateral monocular projection - a method of behavioral fixation was used. This method consists in a forced pecking schedule and a tachistocopic presentation of the stimulus. The pigeon has to discriminate the orientation (vertical, positive; horizontal, negative) of square gratings of increasing spatial frequency. Tests were done with the stimuli appearing 25° below the beak for frontal and 80° back from the beak for lateral viewing, at distances of 10, 20, 40 and 80 cm for each direction. Results show that while frontal acuity decreases with distance, lateral acuity increases with distance. These psychophysical data confirm previous dioptric measurements done on frozen eyes, showing that the pigeon is myopic in the frontal field and hyperopic in the lateral field. Pigeons seem to be well adapted for visually guided frontal tasks at near distances (feeding, landing) and for visually guided lateral tasks at far distances (warning).