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Background: The standard treatment for primary CNS lymphoma (PCNSL) involves high-dose methotrexate-based (MTX) chemotherapy and whole brain radiotherapy (WBRT). This combined regimen prolongs patient survival, but also carries a substantial risk for delayed neurotoxicity particularly in the elderly. However, cognitive outcome evaluations have not been included in most clinical trials., Objective: To assess cognitive functioning and quality of life in PCNSL survivors treated either with WBRT +/- MTX-based chemotherapy or chemotherapy alone., Methods: Twenty-eight PCNSL patients in disease remission received a post-treatment baseline neuropsychological evaluation, and a subset of patients were available for an 8-month follow-up evaluation. Assessment of quality of life and extent of white matter disease on MRI were also performed., Results: Patients displayed mild to moderate impairments across several cognitive domains. These were of sufficient severity to reduce quality of life in half of the patient sample. Comparisons according to treatment type revealed more pronounced cognitive impairment, particularly in the memory and attention/executive domains, among patients treated with WBRT +/- chemotherapy. Extent of white matter disease correlated with attention/executive, memory, and language impairment., Conclusions: PCNSL survivors treated with WBRT +/- chemotherapy displayed more pronounced cognitive dysfunction than patients treated with MTX-based chemotherapy alone.

There is increasing evidence for an influence of directed attention on prepulse inhibition (PPI) of the acoustic startle reflex. However, the existing paradigms for the assessment of this effect have methodological problems and pitfalls. In particular, most previous studies used a paradigm which directed the attention of subjects to the prepulse only. In the present study, we used a modified paradigm which directed the attention of the subjects both to the prepulse and the pulse. Twenty healthy male subjects were instructed trial by trial either to relax or to attend to the startle stimulus and decide whether it was a 'simple' (prepulse alone or pulse alone) or a 'composite' trial (pulse plus a prepulse or postpulse). Directed attention enhanced PPI at the lead interval of 240 ms, but not at the lead interval of 100 ms. This finding is in line with the idea that attention contributes to PPI when there is enough time for the attentional mechanisms to exert an influence. This new paradigm offers a valuable tool for the study of attentional modulation of sensorimotor gating in humans., (Copyright 2004 S. Karger AG, Basel)

The authors evaluated the late neurocognitive profile and progress of memory functions in 60 patients with primary nasopharyngeal carcinoma who had been treated with radiation therapy for more than 2 years. Forty had imaging evidence of temporal lobe injury (TLI-positive), and 20 did not (TLI-negative). The patients and 19 healthy control subjects, matched with the patients for age and educational level, underwent extensive memory assessments. Seventeen patients (10 TLI-positive, 7 TLI-negative) were reassessed after an average of 28 months for progress of memory functions. The patient groups performed significantly worse on most memory tests compared with the normal subjects. Patients with memory complaints had lower scores for verbal memory than those without such complaints. The TLI-positive and TLI-negative groups did not differ significantly from each other in cognitive performance. At follow-up, visual memory performance had deteriorated, while verbal memory remained more stable.

Previous findings suggested the facilitating effect of the electromagnetic field emitted by mobile phones on human attention. This study aimed to examine the relationship between the facilitating effect and the duration of exposure to the electromagnetic field emitted by mobile phones on human attention. Seventy-eight university students were randomly assigned to either an experimental or a control group. Their performance in the administered attention tasks was compared. Participants in the experimental group performed better on one of the two measures of attention only after they had been exposed to the electromagnetic field emitted by the mobile phone for some time. The results seem to suggest that attention functions may be differentially enhanced after exposing to the electromagnetic field emitted by mobile phones. Furthermore, this transient facilitation effect might be dose dependent.

Background: Stereotactic radiotherapy of benign tumors of the base of skull shows excellent tumor control and long survival. Aim is to study the impact of high dose radiation therapy on functions of memory and attention over time., Patients and Methods: 21 patients (age 42 +/- 11 years) with tumors of the base of skull (meningiomas, pituitary gland adenomas) were treated by fractionated stereotactic radiotherapy (mean total dose 56.6 Gy/1.8 Gy). Comprehensive neuropsychological tests and MRI brain scans were performed before, 3, 9 and 21 months after therapy. 14 healthy volunteers were tested in parallel at baseline. In the follow-ups patients were their own controls., Results: In pretreatment tests there were significantly worse test results in comparison to the control group in ten of 32 tests. In postradiation tests only few changes were found in the early-delayed period and not much difference was seen in comparison to the baseline tests. In MRI scans tumor recurrences or radiation induced changes were not found., Conclusion: Radiation with high local doses in target volume extremely close to sensitive brain structures like temporal lobes did not induce significant decline of cognitive functions.

Objective: To investigate longitudinal cognitive functioning in patients with brain tumor treated with modern highly conformal fractionated partial brain radiation therapy (RT)., Methods: Seventeen (of 22 initial consecutive patients) adults with primarily low-grade brain neoplasms who underwent either biopsy or tumor resection were tested at pre-RT baseline and at 3, 6, 12, and 24 months after baseline. Participants were classified as RT-treated nonprogressors (n = 12) or progressors (n = 3) based on serial follow-up structural imaging. Two patients received surgery only and served as controls to help minimize surgical, practice, test form, or other potential non-RT effects. Serial neuropsychological assessments were conducted using alternate forms of the Selective Reminding Test, 10/36 Spatial Recall Test, and Symbol Digit Modality Test (oral, written) as well as the Shipley Scale (baseline only), Wechsler Adult Intelligence Scale-Revised Digit Span, Trail Making Test, and the Symptom Checklist-90-Revised Global Severity Index scale., Results: There was evidence of subtle attention and memory improvement in RT-treated nonprogressors throughout the 2-year period, with no evidence of cognitive decline. In contrast, patients with disease progression evidenced more substantial decline in memory and attention., Conclusions: Partial brain fractionated RT was not associated with adverse neuropsychological effects through the first 2 years following therapy.

In the present study the anatomical projections from the medial cerebellum to the prefrontal cortex (PFC) were investigated in healthy human subjects, using high frequency repetitive transcranial magnetic (rTMS) stimulation and electroencephalography (EEG). Medial cerebellar rTMS, compared to placebo induced a significant shift in anterior asymmetry, from left to right dominance in the fast (30-50 Hz) EEG spectrum, whereas occipital and lateral cerebellum stimulation did not show such an effect. Moreover elevations in mood and alertness were reported again after medial cerebellar stimulation only. Taken together, these data confirm and further specify the assumed cerebellar modulation of PFC activity and affect., (Copyright 2002 Elsevier Science Ireland Ltd.)

Purpose: The aim was to examine low-level 7 Hz-modulated 450 MHz radiation effects on human performance in visually presented neuropsychological tasks associated with attention and short-term memory., Materials and Methods: A homogeneous group of 100 subjects (37 female, 63 male) were randomly assigned to either the exposed (10-20 min, 0.158 mW cm(-2)) or the sham-exposed group. A battery of three different tests measured attention and short-term memory. Task 1 involved alternately selecting black digits from 1 to 25 in ascending order and white digits from 24 to 1 in descending order. The time spent on the task and the number of errors were recorded and analysed. Task 2 involved viewing a picture of 12 objects during 3 s, followed by a list of 24 words. The subject was required to select words representing previously presented objects. In task 3, an array of letters in 10 rows (60 in each row) was presented, and the subject was required to identify all examples of a particular two-letter combination., Results: The results of tasks 1 and 3 showed a significant increase in variances of errors (p<0.05) in the exposed versus the sham-exposed group. The results of task 2 indicated a significant decrease in errors (p<0.05) in the exposed group., Conclusions: The data provide additional evidence that acute low-level exposure to microwaves modulated at 7 Hz can affect cognitive processes such as attention and short-term memory.

Purpose: To assess sustained attention, impulsivity, and reaction time during radiotherapy (RT) for pediatric patients with localized primary brain tumors., Methods and Materials: Thirty-nine patients (median age 12.3 years, range 5.9-22.9) with primary brain tumors were evaluated prospectively using the computerized Conners' continuous performance test (CPT) before and during conformal RT (CRT). The data were modeled to assess the longitudinal changes in the CPT scores and the effects of clinical variables on these changes during the first 50 days after the initiation of CRT., Results: The CPT scores exhibited an increasing trend for errors of omission (inattentiveness), decreasing trend for errors of commission (impulsivity), and slower reaction times. However, none of the changes were statistically significant. The overall index, which is an algorithm-based weighted sum of the CPT scores, remained within the range of normal throughout treatment. Older patients (age >12 years) were more attentive (p < 0.0005), less impulsive (p < 0.07), and had faster reaction times (p < 0.001) at baseline than the younger patients. The reaction time was significantly reduced during treatment for the older patients and lengthened significantly for the younger patients (p < 0.04). Patients with a shunted hydrocephalus (p < 0.02), seizure history (p < 0.0006), and residual tumor (p < 0.02) were significantly more impulsive. Nonshunted patients (p < 0.0001), those with more extensive resection (p < 0.0001), and patients with ependymoma (p < 0.006) had slower initial reaction times., Conclusion: Children with brain tumors have problems with sustained attention and reaction time resulting from the tumor and therapeutic interventions before RT. The reaction time slowed during treatment for patients <12 years old. RT, as administered in the trial from which these data were derived, has limited acute effects on changes in the CPT scores measuring attention, impulsiveness, and reaction time.

Purpose: Aim of this study was the assessment of neuropsychological changes after whole brain irradiation., Patients and Method: 64 patients were tested before, and 29 after whole brain irradiation, including 28 patients with small cell lung cancer (SCLC) before prophylactic cranial irradiation (PCI) and 36 patients with cerebral metastases before therapeutic cranial irradiation (TCI), as well as 14 patients after PCI and 15 after TCI (Table 1). Intelligence, attention and memory were assessed applying a 90-minute test battery of standardized, neuropsychological tests (Table 3)., Results: Patients with SCLC showed test results significantly below average before PCI (n = 28, mean IQ = 83, SD = 17). Neither after PCI, nor after TCI the tested neuropsychological functions decreased significantly (Tables 4, 5). A comparison between SCLC-patients with and without cerebral metastases before whole brain irradiation showed better test-results in patients with cerebral metastases and fewer cycles of preceding chemotherapy (Table 7)., Conclusion: Neuropsychological capacity in patients with SCLC was impaired even before PCI. Possible reason is the preceding chemotherapy. Whole brain irradiation did not induce a significant decline of cognitive functions in patients with PCI or TCI. A decline in a longer follow-up nevertheless seems possible.

The aim of our study was to investigate the effects of acute mobile phone exposure on a range of tasks which tapped capacity and processing speed within the attentional system. Thirty-eight healthy volunteers were randomly assigned to either an experimental group which was exposed to a connected mobile phone or a control group in which the mobile phone was switched off. Subjects remained blind to mobile phone status throughout duration of study. The experimental group were exposed to an electromagnetic field emitted by a 900 MHz mobile phone for 30 min. Cognitive performance was assessed at three points (prior to mobile phone exposure, at 15 and 30 min post-exposure) using six cognitive neuropsychological tests (digit span and spatial span forwards and backwards, serial subtraction and verbal fluency). Significant differences between the two groups were evident after 5 min on two tests of attentional capacity (digit span forwards and spatial span backwards) and one of processing speed (serial subtraction). In all three instances, performance was facilitated following mobile phone exposure. No deficits were evident. These findings are discussed in terms of possible functional and neuroanatomical bases.

Background: In study AML-BFM 87 the relapse rate was lower in patients receiving cranial irradiation (CRT). However, CRT has always been associated with adverse cognitive side effects. Therefore, the impact of CRT on neuropsychological function in children with AML was retrospectively evaluated., Patients: We tested 53 children (30 boys, 23 girls) treated according to the AML-BFM-87 protocol (median age at diagnosis: 8.5 years, range 0.3 - 17.5; median time since diagnosis: 5.7 yrs, 3.8 - 10.7 yrs). To avoid any bias from additional therapy elements, patients with relapse or initial CNS involvement and transplanted patients were excluded (n=32). Our cohort was representative of the total group of 104 long term survivors of study AML-BFM 87. CNS prophylaxis consisted of ARA-C i.th., high dose ARA-C i. v. and either no CRT (n=15) or CRT (n=38) at a dose of 12 - 18 Gy depending on age., Methods: Neuropsychological function was evaluated by psychological tests of attention and concentration (test d2 by Brickenkamp) and an intelligence test (Progressive Matrices by Raven). In addition, patients and their parents were interviewed about the occurrence of learning problems, subjective deficits in concentration and physical impairment., Results: In the total group, no significant differences were seen between irradiated and non-irradiated patients regarding the psychological tests. However, the irradiated patients scored below the non-irradiated control group in test "d2" (concentration: 41st vs. 59th percentile). In the interview, irradiated patients tended to report more learning problems (lp) (10/36 vs. 1/14; p=0.15) and subjective deficits in concentration (con). In irradiated girls (con: 6/15 vs. 0/8; p=0.06; lp: 5/15 vs. 0/8; p=0.12) and younger patients (0 - 5 years at diagnosis; con: 7/12 vs. 2/9; p=0.18; lp 3/10 vs. 1/9; p=0.18) this trend was even more pronounced., Conclusion: Children with AML and CRT had no significant intellectual impairment in standardized tests when compared to non-irradiated patients. However, more irradiated patients reported learning problems and subjective concentration deficits.

Background: The objective of the current study was to evaluate the short-term effects of radiotherapy on attention and memory performance in patients with brain tumors., Methods: Thirteen patients underwent a neuropsychologic examination on three occasions: at baseline before radiotherapy, which lasted for 6 weeks; within 2 weeks after the completion of radiotherapy; and 3 months after the completion of radiotherapy. Thirty healthy individuals were studied at baseline as a control group. Verbal, visuomotor, and memory tests were administered. Attentional performances were examined using CogniSpeed reaction time software., Results: At baseline, the patients scored significantly lower than the controls in tests of semantic memory (Similarities; P = 0.002), visuoconstructive skill (Block Design; P = 0.028), and visual and verbal memory (recall of 20 objects: immediate, P = 0.017; delayed, P = 0.002; recall of 30 paired word associates: immediate, P = 0.002; delayed, P = 0.005). The patients performed significantly more poorly than the control group on the Two-Choice Reaction Time test (P = 0.047), the Subtraction test (P = 0.042), and the Vigilance test (P = 0.023). After radiotherapy, the performance of the patients did not worsen on any measure, whereas their conscious cognitive processing was improved (P = 0.002)., Conclusions: Treatment with radiotherapy did not cause negative short-term effects on attentional and memory functions in patients with brain tumors who received a radiation dose of 54.5 grays. The cognitive deficits found in these patients were evident at baseline before radiotherapy. Thus, it seems likely that the deficits were associated with the tumor itself and/or the surgical procedures., (Copyright 2001 American Cancer Society.)

This study examined the effect of exposure to the electromagnetic field emitted by mobile phones on human attention. Three measures of attention were administered to 72 teenagers, 37 of whom were mobile phone users. The results showed that the mobile phone users performed better on one of the three measures of attention than did the non-mobile phone users. The results suggest that exposure to the electromagnetic field emitted by mobile phones may have a mild facilitating effect on attention functions, which is consistent with previous observations that exposure to the electromagnetic field has a facilitating effect on cognitive processing. The possibility that mobile phone users may be naturally better at multiple tasking tasks was discussed.

Purpose: Prospective evaluation of chronic radiation effects on the healthy adult brain using neuropsychological testing of intelligence, attention, and memory., Methods and Materials: 58 patients (43 +/- 10 yr) undergoing hyperfractionated total body irradiation (TBI) (TBI, 14.4 Gy, 12 x 1.2 Gy in 4 days) before bone marrow or peripheral blood stem cell transplantation were prospectively included. Twenty-one recurrence-free long-term survivors were re-examined 6-36 months (median 27 months) after completion of TBI. Neuropsychological testing included assessment of general intelligence, attention, and memory using normative, standardized psychometric tests. Mood status was controlled, as well. Test results are given as IQ scores (population mean 100) or percentiles for attention and memory (population mean 50)., Results: The 21 patients showed normal baseline test results of IQ (101 +/- 13) and attention (53 +/- 28), with memory test scores below average (35 +/- 21). Test results of IQ (98 +/- 17), attention (58 +/- 27), and memory (43 +/- 28) showed no signs of clinically measurable radiation damage to higher CNS (central nervous system) functions during the follow-up. The mood status was improved., Conclusion: The investigation of CNS toxicity after hyperfractionated TBI showed no deterioration of test results in adult recurrence-free patients with tumor-free CNS. The median follow-up of 27 months will be extended.

Recently, several experiments have indicated that the left and right prefrontal cortex (PFC) are differently involved in emotional processing. The aim of this study was to investigate the role of the left and right PFC in selective attention to angry faces by using a pictorial emotional Stroop task. Slow repetitive transcranial magnetic stimulation (rTMS) was applied to the left and right PFC of 10 female subjects for 15 min on separate days. Results showed a significant effect of stimulation position: right PFC rTMS resulted in selective attention towards angry faces, whereas left PFC rTMS resulted in selective attention away from angry faces. This finding is in accordance with theoretical accounts of the neural implementation of approach and withdrawal systems.

Background: Cranial radiation therapy (CRT) has been suggested to be a principal factor responsible for long term neurocognitive deficits in survivors of acute lymphoblastic leukemia (ALL). However, neither reduction of the irradiation dose nor the elimination of irradiation entirely appear to have abolished neurocognitive impairment in long term ALL survivors. Positron emission tomography (PET) and [(18)F]-fluorodeoxyglucose (FDG) can be used to quantitate cerebral glucose metabolism, a potential indicator of treatment-induced adverse central nervous system (CNS) effects. The purpose of this study was to assess whether CRT is associated with defects in cerebral glucose metabolism in long term ALL survivors. The authors also studied whether chemotherapy and/or the severity of disease have deleterious effects on glucose metabolism., Methods: Forty long-term survivors of childhood ALL were studied using FDG PET. All subjects went through an elaborate neurocognitive assessment. In 20 of these children, the prophylactic treatment of the CNS had been CRT combined with methotrexate (MTX), and it was MTX only in the remaining 20 children., Results: No major differences were found in the regional cerebral glucose utilization or in neurocognitive performance between the irradiated and nonirradiated groups. A high leukocyte count at the time of diagnosis was found to be associated inversely with cerebral glucose utilization., Conclusions: CRT does not appear to affect cerebral glucose metabolism in long term survivors of ALL. By contrast, the association between the leukocyte count and glucose utilization implies that disease severity may be partly responsible for adverse CNS effects in long term survivors of childhood ALL., (Copyright 2000 American Cancer Society.)

Two double-blind studies were performed to examine magnetic field (MF) exposure effects and to determine the impact of temporal variation (continuous vs. intermittent exposure) of 100 mu T(rms) 50 Hz MF diurnal exposure on psychological and psychophysiological parameters in healthy humans. Three cephalic exposure sessions of 30-min, i.e., sham, continuous, and intermittent (15 s ON/OFF cycles) MF conditions, were involved. Each subject participated in all sessions, which were spaced at 1-wk intervals. In each session, mood ratings and performance measures were obtained before, during, or after exposure and several electrophysiological data (event-related brain potentials [ERP]) were recorded after each exposure session. These criteria were chosen to evaluate sensory functions as well as automatic and voluntary attentional processes. In experiment 1, 21 healthy male volunteers (20 to 27 years of age) were studied. Ten subjects were exposed at 13:30 h, and 11 subjects were exposed at 16:30 h. Statistically significant changes in the amplitude of ERP were observed after MF exposure in the dichotic listening task, indexing selective attention processes. Eighteen of the 21 original male volunteers took part in experiment 2, undertaken to better understand the results related to information processing involved in selective attention and control for ultradian rhythmicity. Exposure time for all the subjects was at 13:30 h. The analysis of the data again revealed significant amplitude changes of the ERP recorded in the dichotic listening task. Moreover, they demonstrated ERP latency and reaction time slowing in the oddball paradigm, a visual discrimination task after real MF exposure. These results also indicate that a low level 50 Hz MF may have a slight influence on event-related potentials and reaction time under specific circumstances of sustained attention., (Copyright 1999 Wiley-Liss, Inc.)

Twenty volunteers participated in two experiments exploring the acute effects of using the mobile phone Motorola GSM 8700 on the functions of the CNS. When speaking (5 minutes reading a text from daily newspapers) the electromagnetic fields from the mobile apparatus did not affect the visual evoked potentials. Also a 6-min exposure did not reveal any effect of electromagnetic fields on the results in two tests (memory and attention) performed while speaking into the mobile. On the other hand the phone call itself strongly influenced the performance in a secondary task applying a test of switching attention which is a good model for driving a car. The response and decision speed were significantly worse. This is a proof that even a slight psychological stress involved in calling while driving can be a great risk.

Establishing safe exposure levels for microwave irradiation is important since new, more powerful emitters are developed and the potential for accidental exposure is increasing. Analysis of the behavior of exposed laboratory animals has proven to be an accurate and repeatable metric for assessing the effects of microwave irradiation. Determining the specific absorption rate (SAR) at which an animal will cease an ongoing behavior has proven useful in the development of safe exposure levels for humans. Behaviors that have been used are simple tasks, and the point at which behavior changes significantly or ceases has often been referred to as "work stoppage." The tasks have been used to evaluate the overwhelming effects of heating produced by microwave irradiation. Both whole-body exposures and partial-body exposures with hotspots have been evaluated. Recent studies have suggested that microwave effects on specific cognitive aspects of behavior such as attention, learning, memory, discrimination, and time perception may occur at SAR levels far below the SARs needed to cause work stoppage. New research studies are underway to evaluate microwave-induced cognitive effects.

Purpose: The purpose of this study was to investigate neuropsychological effects of radiosurgery in patients with cerebral arteriovenous malformation (AVM), with special focus on attention and memory. This report describes the study setup and presents the first results during a follow-up of up to 1 year., Materials and Methods: Seventy-nine patients were studied before, acutely after radiosurgery, and during the regular follow-up (subacute phase: Weeks 6-12, chronic phase: Months 6-12). Radiosurgery was performed using a modified linear accelerator (minimum doses to the target volume: 15-22 Gy, median 20 Gy). Estimated whole brain dose was 0.5 to 2 Gy. Neuropsychological testing included assessment of general intelligence (Wechsler Adult Intelligence Scale), attention (modified Trail-Making Test A, Digit Symbol Test, D2 Test, Wiener Determination Machine) and memory (Rey Auditory Verbal Learning Test, Benton Visual Retention Test). During follow-up, alternate test versions were used. Neuropsychological deficits were defined as a test score of at least one standard deviation (SD) below the mean of the normal distribution., Results: The pretherapeutic evaluation revealed marked deviations from the normal population; 24% had deficits in intelligence (range 23-31% in different subtests), attention (35%, 23-59%) and memory (48%, 31-61%). The overall percentage of aberrant results was reduced by 12% (memory) to 14% (attention) in the chronic phase up to 12 months after therapy. The improvement in test scores was significant (p < 0.05) in 3 of 4 subtests of attention functions., Conclusions: The acute tolerance of radiosurgery seems to be very good in these patients, showing no relevant increase in number of patients with neuropsychological deficits. Although the long-term follow-up needs to be further increased, our data indicate a tendency to slight improvement in the overall neuropsychological performance of AVM patients in the chronic phase after radiosurgery.

Objectives: To examine whether the power frequency magnetic field of 0.6mT applied to humans has an effect on cognitive function as has been suggested by animal studies. These fields are less than the suggested intervention level in the UK of 1.6mT and are similar to those found close to some domestic appliances., Method and Materials: A randomized three-way cross-over design using a battery of computerized cognitive function tests were used in the presence or absence of a 50Hz or static magnetic field. Sixteen healthy volunteers undertook two training and three test sessions with a 50Hz or static 0.6 mT magnetic field from a set of coils centred on the head., Results: In response to the 50 Hz field, disruptions of accuracy were seen from an attentional task (the ability to correctly recognize words shown 20min previously and the ability to maintain a string of digits in working memory). There was no similar response to comparable levels of static magnetic field., Conclusions: These tests indicated at least temporary deterioration in attention, and working and secondary memory performance while a 50 Hz field is applied. There were no adverse effects on speed from any of the tasks. It was not possible in this study to be sure if these effects were persistent.

Performance on a wide range of perceptual tasks improves with practice. Most accounts of perceptual learning are concerned with changes in neuronal sensitivity or changes in the way a stimulus is represented. Another possibility is that different areas of the brain are involved in performing a task while learning it and after learning it. Here we demonstrate that the right parietal cortex is involved in novel but not learned visual conjunction search. We observed that single pulse transcranial magnetic stimulation (TMS) to the right parietal cortex impairs visual conjunction search when the stimuli are novel and require a serial search strategy, but not once the particular search task has been learned. The effect of TMS returns when a different, novel, serial search task is presented.

The effects of low level chronic ionising irradiation (12.9 cGy/day on the sensory attention to the stimuli of different modalities (somatosensory, visual, odor) of Wistar rats were studied. Analysis of animals behaviour was made after they had received the different doses of irradiation: 4, 6, 8, 10, 15 and 20 Gy. It was founded, that the attention and exploratory activity of rats is significantly decreased up to 20-30% after 4-6 Gy. The irradiation doses 8 Gy did not change animal behaviour as compared to control animals, but doses 10, 15 and 20 Gy decreased the exploratory activity as well as sensory attention of rats to 3-5-times as compared to previous dose. Such a wave-like way of behaviour reflects the functioning of an adaptive mechanism. Biochemical data indicated that after 5 months of the irradiation (dose 20 Gy) the level of phospholipids, lysophosphatidylcholine, phosphatidylethanolamine, phosphatidylcholine, cholesterol were decreased.

This paper presents the results of experiments on school children living in the area of the Skrunda Radio Location Station (RLS) in Latvia. Motor function, memory and attention significantly differed between the exposed and control groups. Children living in front of the RLS had less developed memory and attention, their reaction time was slower and their neuromuscular apparatus endurance was decreased.

Cognitive and educational sequelae are inconsistently reported in children treated with cranial irradiation for acute lymphoblastic leukaemia. This study investigated differences in these skills after cranial irradiation, controlling the effects of chemotherapy and psychosocial factors. Three groups were evaluated: 100 children diagnosed with acute lymphoblastic leukaemia and treated with cranial irradiation and chemotherapy; 50 children diagnosed with acute lymphoblastic leukaemia or other cancers and treated with chemotherapy alone; and a healthy control group of 100 children. Children in the clinical groups stopped treatment at least two years before evaluation and had no history of relapse. Children were aged between 7 and 16 at the time of assessment. Evaluation included cognitive, educational, and behavioural measures. Analyses found that children receiving cranial irradiation and chemotherapy performed more poorly than non-irradiated groups on intellectual and educational tests, with verbal and attentional deficits most pronounced. Children receiving chemotherapy alone performed similarly to controls, suggesting such treatment is not associated with adverse neurobehavioural sequelae.

Single microwave pulses at 1.25 GHz were delivered to the head and neck of male Long-Evans rats as a prestimulus to acoustic and tactile startle. For acoustic startle, pulses averaging 0.96 microsecond in duration were tested with two specific absorption rate (specific absorption) ranges, 15.0-30.0 kW/kg (16.0-44.2 mJ/kg) and 35.5-86.0 kW/kg (66.6-141.8 mJ/kg), delivered 201, 101, 51, 3, and 1 ms before and 1 ms after onset of a startling noise. The low-intensity pulse did not affect peak amplitude, integral, or latency of the whole-body startle response. The high-intensity pulse at 101 and 51 ms inhibited the startle response by decreasing peak amplitude and integral; at 201 and 51 ms latency was increased. The high-intensity pulse at 1 ms enhanced the startle response by increasing peak amplitude and at 3 ms by increasing integral. For tactile startle, either microwave pulses averaging 7.82 microseconds in duration and 55.9-113.3 kW/kg (525.0-1055.7 mJ/kg) or 94 dB SPL clicks were delivered 157, 107, 57, and 7 ms before and 43 ms after onset of a startling air burst. The microwave pulse at 57 ms inhibited the startle response by decreasing peak amplitude; at 157, 107, 57, and 7 ms it increased latency. The microwave pulse at 43 ms after onset enhanced the startle response by increasing peak amplitude. The acoustic click at 157 and 57 ms inhibited the startle response by decreasing peak amplitude; at 157,2 107, and 57 ms it increased latency.(ABSTRACT TRUNCATED AT 250 WORDS)

This human exposure study examined the relationship between field strength and biological response and tested whether the exposure levels at which the greatest effects occur differ for different endpoints. Three matched groups of 18 men each participated in two 6 h exposure test sessions. All subjects were sham exposed in one session. In the other session, each group of subjects was exposed at a different level of combined electric and magnetic field strength (low group:6 kV/m, 10 microT; medium group:9 kV/m, 20 microT; and high group: 12 kV/m, 30 microT). The study was performed double blind, with exposure order counterbalanced. Significant slowing of heart rate, as well as alternations in the latency and amplitude of event-related brain potential measures derived from the electro encephalogram (EEG), occurred in the group exposed to the 9 kV/m, 20 microT combined field (medium group). Exposure at the other field strength levels had no influence on cardiac measures and differential effects on EEG activity. Significant decrements in reaction time and in performance accuracy on a time estimation task were observed only in the low group. These results provide support for the hypothesis that humans may be more responsive to some combinations or levels of field strength than to others and that such differences in responsivity may depend, in part, on the endpoint of interest.

Antineoplastic treatment has a deleterious effect on intellectual functions, which is mainly attributable to radiotherapy. With the object of determining the neuropsychological disturbances associated with brain irradiation in the child, and to try to differentiate them from the effects caused by the other types of treatment (surgical and chemotherapy) as well as from the effects of the tumor itself, a cross-sectional study was carried out in 25 survivors of medial edge intracranial tumors. In order to monitor the effect of systemic chemotherapy on the cognitive functions, and the effect of prolonged absence from school, two control groups were formed, one made up of subjects treated with chemotherapy for extracranial tumors, and the other of patients with non-malignant chronic disease. Neuropsychological functions were measured using the Spanish version of the Wechsler scale, as well as the following tests: Spreen-Benton, ITPA and TALE scales, Yuste Memory Test, Thurstone Attention Test, and the Rey Complex Figure. In addition to a progressive decline found in the full scale intelligence quotient in children irradiated for intracranial tumors, variance analysis showed that these patients deteriorate mainly in visual attention and memory, but also significantly in verbal fluency and in the Performance Intelligence Quotient and all its subtests, when compared to the control groups. Visual attention and the Wechsler Picture Arrangement and Block Designs, were the tests whose decline correlated with the total radiation administered. The article relates this specific neuropsychological injury with the total brain irradiation dose but also with the structures located in the cone-down fields of irradiation to boost regions in the middle edge intracranial content.

Although radiotherapy (XRT) is a necessary course of treatment to prolong life expectancy in patients with many types of brain neoplasms, it has damaging effects that are little understood. We used a comprehensive neuropsychological battery to evaluate five patients with low-grade brain tumors prior to XRT and then at 3-month intervals up to 9 months postcompletion of XRT. We matched patients by age and education with six normal control subjects to assess baseline impairment. In intrasubject comparisons, we examined change over time postcompletion of XRT. In spite of varying locations of tumors, all patients showed deterioration in long-term memory at a mean of 1.5 months postcompletion of XRT. Patients also consistently demonstrated a rebound effect between means of 4.7 and 7.6 months post-XRT. We found no changes over time in working memory, attention, visuospatial processes, or on any other neuropsychological test with the exception of information-processing speed, which quickened over time. Functional measures of fatigue and mood did not correlate significantly with the long-term memory scores. Long-term memory appears sensitive to the proposed white matter changes thought to be the mechanism for the early-delayed effects of XRT. Our findings suggest a neurobehavioral model for studying the effects of XRT on brain functioning.

After ibotenate (10.0 mg/ml) lesions to the nucleus basalis and medial septal regions, at the source of the cortical and hippocampal branches of the forebrain cholinergic projection system, rats displayed long-lasting stable impairment in reference and working memory in both spatial (place) and associative (cue) radial maze tasks. Cell suspension transplants of cholinergic-rich fetal basal forebrain tissue dissected at embryonic day 15 substantially improved all aspects of radial maze performance to a comparable degree whether sited in cortex, hippocampus, or both regions of the host brain. No additive effects were obtained with grafts in both terminal regions, but total graft volume, assessed stereologically, showed a significant negative correlation with error scores. Rats with behaviourally effective grafts, like controls, were disrupted in the place task when tested in dim light which obscured extra-maze spatial cues. Lesioned rats were not affected by change in lighting. Grafts of cholinergic-poor fetal hippocampal tissue did not improve radial maze performance; neither did grafts of cholinergic-rich tissue placed within the host basal forebrain lesion sites. In rats with cholinergic-rich terminal grafts, cortical and hippocampal choline acetyltransferase activity was restored to control level, commensurate with site of transplant, whereas it was significantly reduced in lesioned animals and those with functionally ineffective grafts. The indiscriminate error pattern and insensitivity to changes in lighting shown by lesioned rats suggested that lesioning primarily disrupted attention rather than short- or long-term spatial or associative memory processes. Since rats with cholinergic-rich grafts showed both reduced errors and recovery of stimulus control, the data indicated that grafts affected information processing, rather than changes in motor or motivational processes. Changes in choline acetyltransferase activity and the behavioural efficacy of cholinergic-rich grafts are consistent with the involvement of acetylcholine in the behavioural deficits and recovery displayed by lesioned and grafted groups, but do not rule out contributions from other factors. The equipotency of grafts within each terminal region suggests also that there may be a considerable degree of functional cooperation between the two branches of the forebrain cholinergic projection system. Functional recovery may involve local, nonspecific synaptic or paracrine mechanisms within the target regions, since grafts were efficacious only when placed in the terminal areas, but not when sited homotopically in the basal forebrain, indicating that they did not achieve any functionally significant structural repair to the host brain at that site.

A systematic study of verbal and nonverbal memory and learning was undertaken in long-term survivors of acute lymphoblastic leukemia to assess the incidence and pattern of impairments and to determine the relationship between these deficits and computed tomography (CT) brain scan abnormalities. Twenty-three children who had received cranial irradiation (2,400 cGy) and intrathecal chemotherapy as central nervous system (CNS) preventive therapy and who were off all therapy for at least 4 years were evaluated. On the basis of their CT brain scan findings, patients were divided into three groups: those with intracerebral calcifications (n = 5), those with cortical atrophy (n = 8), and those with normal CT findings (n = 10). Significant deficits in verbal memory (p less than 0.025) and verbal learning (p less than 0.05) were observed that were associated with the presence and type of CT brain scan abnormalities; the greatest impairments were observed in patients with calcifications. No significant differences between CT scan groups were found for nonverbal memory and learning. Previous evaluation of attentional processing in these patients using reaction time tests had revealed the presence of deficits primarily in the ability to sustain attention. Combining those data with findings from the present study showed that memory impairments, particularly those in short-term memory, were primarily attributable to an underlying attentional defect that affect the encoding stage of memory processing.

Twenty-six children with primary brain tumors were studied prospectively with regard to their sensorimotor, intellectual, academic, and emotional status. Serial evaluations were conducted after surgery (pre-irradiation) and six months after the completion of radiation therapy. The timing of the second evaluation was chosen so as to antedate the late effects of irradiation. Children over 6 years old displayed significant improvement of intellectual function over time, with only 11% exhibiting deterioration on one or more cognitive parameters. In contrast, 68% of younger children clinically deteriorated in one or more areas of intellectual functioning, with prominent difficulties in memory and selective attention for age. Children under 6 years old with supratentorial tumors were less likely than those with posterior fossa tumors to improve their cognitive performance. At the second evaluation, 23% of the patients were functioning below normal (IQ less than 80) intellectually, with 50% of the younger children and 11% of the older children receiving special educational assistance. Approximately 40-50% of the patients manifested emotional adjustment problems at each evaluation. The results are discussed in terms of the clinical need to follow similar patient populations with formal psychological assessments over time, and in terms of the difficulties involved in defining factors that determine the functional status of children surviving brain tumors.