Proton magnetic resonance spectroscopy in the frontal and temporal lobes of neuroleptic naive patients with schizophrenia

Studies with proton magnetic resonance spectroscopy (MRS) have reported abnormalities in N-acetyl-aspartate (NAA), amino acids (AA) and choline (Cho) to creatine (Cr) ratios associated with schizophrenia. We report data on the three ratios in a sample of 18 neuroleptic naive patients with first-episode schizophrenia (eight studied in the dorsolateral prefrontal and 10 in the midtemporal lobe) and 24 healthy controls (14 studied in prefrontal and 10 in midtemporal lobes). Frontal lobe proton spectra were acquired with the stimulated-echo acquisition mode (STEAM) pulse sequence (echo time 21 ms, repetition time 2 s). Temporal lobe proton spectra were acquired with the point-resolved spectroscopy (PRESS) pulse sequence (echo time 16-21 ms, repetition time 2 s). Upon comparison with normal controls, NAA/Cr ratios were reduced in patients both for the frontal and the temporal lobe. By contrast, Cho/Cr ratios were slightly elevated in frontal and reduced in temporal lobes; whereas, AA/Cr ratios were normal in frontal and markedly increased in the temporal lobe. The reduced NAA/Cr ratios suggest lower neuronal viability in patients and is consistent with findings of reduced brain volume in both frontal and temporal regions.

Subcortical MRI volumes in neuroleptic-naive and treated patients with schizophrenia

OBJECTIVE

This study examined whether subcortical volumes of the basal ganglia and thalamus in schizophrenic patients are related to neuroleptic exposure and symptom severity.

METHOD

Basal ganglia substructures and thalamic volumes were measured with magnetic resonance imaging in 96 patients with schizophrenia (50 men and 46 women) and 128 healthy comparison subjects (60 men and 68 women). Twenty-one of the patients were neuroleptic-naive; of the 75 previously treated patients, 48 had received typical neuroleptics only, and 27 had received typical and atypical neuroleptics. The relation of volume measures to treatment status, exposure to neuroleptics, and symptoms was examined.

RESULTS

The neuroleptic-naive patients did not differ from the healthy comparison subjects in subcortical volumes except for lower thalamic volume. In the neuroleptic-naive group, volumes did not correlate with severity of negative symptoms, but higher volumes in both the thalamus and the putamen were associated with more severe positive symptoms. The previously treated group showed higher volumes in the putamen and globus pallidus than the healthy comparison subjects and the neuroleptic-naive patients. In the treated group, a higher dose of a typical neuroleptic was associated with higher caudate, putamen, and thalamus volumes, whereas a higher dose of an atypical neuroleptic was associated only with higher thalamic volume. Higher subcortical volumes were mildly associated with greater severity of both negative and positive symptoms.

CONCLUSIONS

Increased subcortical volumes in treated schizophrenic patients seem to be medication-induced hypertrophy. This hypertrophy could reflect structural adaptation to receptor blockade and may moderate the effects of neuroleptic treatment.

MMPI-2 characteristics of adults diagnosed with attention deficit disorder

Attention Deficit Disorder (ADD) has been increasingly recognized as extending into adulthood, affecting occupational, interpersonal, and psychological functioning. The Minnesota Multiphasic Personality Inventory (MMPI) and its revision (MMPI-2) have been widely used in the assessment of patients with psychiatric disorders, but few studies have attempted to characterize the personality profiles of individuals with ADD and none have used the MMPI-2. Thirty-three patients with ADD and 33 schizophrenia patients were compared to 46 healthy control subjects on the MMPI-2 validity, clinical and Harris-Lingoes scales. With the exception of significantly lower scores for general affective distress (F), thought disorder (Sc), and paranoia (Pa), ADD subjects demonstrated remarkably similar profiles to those seen in the schizophrenia group. Significant differences between the three groups were found on a majority of the clinical scales, with ADD subjects showing similar profile elevations as schizophrenic subjects on both clinical- and sub-scales. These results were consistent with previous research using the original MMPI in adults with ADD, and confirm that examination of MMPI-2 profiles may be a useful diagnostic aid for this disorder.

Frontotemporal cerebral blood flow change during executive and declarative memory tasks in schizophrenia: a positron emission tomography study

Schizophrenia affects prefrontal and temporal-limbic networks. These regions were examined by contrasting regional cerebral blood flow (rCBF) during executive (Wisconsin Card Sorting Test [WCST]), and declarative memory tasks (Paired Associate Recognition Test [PART]). The tasks, and a resting baseline, were administered to 15 patients with schizophrenia and 15 healthy controls during 10 min positron emission tomography 15O-water measures of rCBF. Patients were worse on both tasks. Controls activated inferior frontal, occipitotemporal, and temporal pole regions for both tasks. Similar results were obtained for controls matched to level of patient performance. Patients showed no activation of hypothesized regions during the WCST and activated the dorsolateral prefrontal cortex during the PART. On the PART, occipitotemporal activation correlated with better performance for controls only. Better WCST performance correlated with CBF increase in prefrontal regions for controls and in the parahippocampal gyrus for patients. Results suggest that schizophrenia may involve a breakdown in the integration of a frontotemporal network that is responsive to executive and declarative memory demands in healthy individuals.

Premorbid educational attainment in schizophrenia: association with symptoms, functioning, and neurobehavioral measures

BACKGROUND

The purpose of this study was to examine the association of educational attainment with phenomenology and neurobehavioral measures assessing brain structure and function in schizophrenia.

METHODS

One hundred sixty-two patients with schizophrenia were divided into two groups on the basis of educational attainment: > or = 13 years of education was the cutoff between the high and low groups. The two education groups were compared on symptomatology, functioning, and subsamples on neuropsychological profile, brain volume by magnetic resonance imaging, and brain metabolism by fluorodeoxyglucose positron-emission tomography.

RESULTS

The patients with more education had lower levels of psychotic symptomatology than their counterparts with less education. This was most evident for affective flattening, alogia, avolition, and bizarre behavior. The higher education group also had better ratings on premorbid adjustment, and the engagement and vocational factors of the Quality of Life Scale. Patients in the high education group also performed better on the neuropsychological battery. There were no brain volume differences or differences in brain metabolism between the two education groups.

CONCLUSIONS

Education is an important indicator of premorbid function and is related to the clinical presentation of schizophrenia.

P50 abnormalities in schizophrenia: relationship to clinical and neuropsychological indices of attention

While the P50 component (50-60-ms latency) of the auditory evoked potential has been reported as abnormal in schizophrenia, few studies have examined the relationship between this abnormality and clinical or neuropsychological measures. To examine these possible relationships, mid-latency auditory evoked potentials were recorded at the CZ recording site of 47 patients with schizophrenia in response to binaural clicks presented at three stimulus rates: 1, 5 and 10/sec. A sub-sample of patients were then divided into high- (n = 15) and low-P50 abnormality (n = 16) groups based on a median split of the P50 amplitude at a rate of 10/sec (a greater amplitude at this rate suggests a greater abnormality in recovery) of the entire sample. Only those patients with complete neuropsychological and clinical data and who were reasonably matched on demographic dimensions were included. A multivariate analysis of variance of 11 neuropsychological function profile scores showed a significant group x global score interaction (Hotelling t = 3.97, p < 0.005). The high-abnormality group had relatively greater deficits for attention profile scores than for the remaining neuropsychological measures. An analysis of global subscores for SAPS and SANS clinical measures revealed a significant difference only for the SANS attention subscale (p < 0.05). The high-abnormality group was rated as more severe on the attention measure. These convergent findings across both phenomenological and neuropsychological measures suggest that abnormalities in P50 recovery may be linked to deficits in attention processes in schizophrenia.

The 1996 outbreak of dengue hemorrhagic fever in Delhi, India

A major outbreak of dengue hemorrhagic fever (DHF) affected more than 10,000 people in Delhi and neighboring areas in 1996. The outbreak started in September, peaked in October to November and lasted till early December. The clinical and laboratory data of 515 adult patients admitted to Lok Nayak Hospital, New Delhi were reviewed. Fever (100%), myalgias and malaise (96%), abdominal pain (10.2%) and vomiting (8.7%) were the prominent presenting features. Hemorrhagic manifestations were seen in all patients- a positive tourniquet test (21.2%), scattered petechial rash (23.07%), confluent rash (2.7%), epistaxis (38.4%), gum bleeds (28.06%) and hematemesis (22.86%) being the major bleeding manifestations. Hepatomegaly was observed in 96% of the patients. Laboratory investigations revealed thrombocytopenia, hemoconcentration and leukopenia. Serological confirmation with a microcapture ELISA technic was done in 143/515 patients. The mortality rate was 6.6% and, multiple bleeding manifestations, severe thrombocytopenia, hypoproteinemia and dengue shock syndrome (DSS) were associated with a higher mortality.

Parallel loss of presynaptic and postsynaptic dopamine markers in normal aging

Aging of the human brain is associated with a decline in dopamine (DA) function, generally interpreted as reflecting DA cell loss. Positron emission tomography studies revealed that in healthy individuals, the age-related losses in DA transporters (presynaptic marker) were associated with losses in D2 receptors (postsynaptic marker) rather than with increases as is known to occur with DA cell loss. This association was specific for DA synaptic markers, because they were not correlated with striatal metabolism. Furthermore, the association was independent of age, suggesting that a common mechanism regulates the expression of receptors and transporters irrespective of age.

Frontotemporal cerebral blood flow change during executive and declarative memory tasks in schizophrenia: a positron emission tomography study

Schizophrenia affects prefrontal and temporal-limbic networks. These regions were examined by contrasting regional cerebral blood flow (rCBF) during executive (Wisconsin Card Sorting Test [WCST]), and declarative memory tasks (Paired Associate Recognition Test [PART]). The tasks, and a resting baseline, were administered to 15 patients with schizophrenia and 15 healthy controls during 10 min positron emission tomography 15O-water measures of rCBF. Patients were worse on both tasks. Controls activated inferior frontal, occipitotemporal, and temporal pole regions for both tasks. Similar results were obtained for controls matched to level of patient performance. Patients showed no activation of hypothesized regions during the WCST and activated the dorsolateral prefrontal cortex during the PART. On the PART, occipitotemporal activation correlated with better performance for controls only. Better WCST performance correlated with CBF increase in prefrontal regions for controls and in the parahippocampal gyrus for patients. Results suggest that schizophrenia may involve a breakdown in the integration of a frontotemporal network that is responsive to executive and declarative memory demands in healthy individuals.

Indication to surgical management of cerebellar hemorrhage

Few reports have compared patients operated for cerebellar infarcts with those operated for cerebellar hemorrhage. Considering our previous paper about patients with massive cerebellar infarcts, we report on our surgical experience with five patients with cerebellar hemorrhage. The indication for operation was decreased consciousness with signs of brainstem compression. In all patients hydrocephalus was absent or mild, as opposed to patients with cerebellar infarcts. Suboccipital craniotomy with hematoma evacuation was therefore the surgical procedure of choice. The outcome was worse than in patients with cerebellar infarcts. We conclude that depressed mental state in cerebellar hemorrhage is mainly due to pressure of the cerebellum on the activating reticular system of the brainstem. The surgical approach to patients with bleeding in the cerebellum differ somewhat from that of patients with cerebellar infarcts in timing and kind of first choice procedure.

Association between decline in brain dopamine activity with age and cognitive and motor impairment in healthy individuals

OBJECTIVE

Although it is documented that brain dopamine activity declines with age, the functional significance of this is not known. This study assessed the relation between measures of brain dopamine activity and indexes of motor and cognitive function in healthy individuals.

METHOD

Thirty healthy volunteers aged 24-86 years were studied with positron emission tomography and [11C]raclopride to assess dopamine D2 receptors. All subjects underwent a neuropsychological test battery that included tasks found to be sensitive to dopamine alterations in patients with neurodegenerative disease and control tasks.

RESULTS

Transfer of [11C]raclopride from plasma to brain in the striatum and cerebellum was not affected by age. In contrast, D2 receptor availability in the caudate and putamen declined with age. Correlations between D2 receptors and neuropsychological test performance were strongest for the motor task (Finger Tapping Test) and were also significant for most tasks involving frontal brain regions, including measures of abstraction and mental flexibility (Wisconsin Card Sorting Test) and attention and response inhibition (Stroop Color-Word Test, interference score). These relationships remained significant after control for age effects.

CONCLUSIONS

Age-related decreases in brain dopamine activity are associated with a decline in motor function and may also contribute to impaired performance on tasks that involve frontal brain regions. Interventions that enhance dopamine activity may improve performance and quality of life for the elderly. The fact that correlations remained significant after age effects were partialed out suggests that dopamine activity may influence motor and cognitive performance irrespective of age.

Depression in schizophrenia: II. MRI and PET findings

BACKGROUND

Despite consistent descriptions of depressive symptoms in schizophrenia, little is known about their neurobiology. The purpose of this study was to examine the association of depression in schizophrenia with measures of brain anatomy and metabolism.

METHODS

Seventy-nine patients were grouped according to their ratings on the Hamilton Depression Rating Scale (HDRS): > or = 18 was the cutoff between the "high" and "low" depression groups. All patients underwent clinical and magnetic resonance imaging (MRI) evaluation, and a subsample of 37 underwent 2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) measurements of cerebral glucose metabolism.

RESULTS

The high depression group had larger bilateral temporal lobe volumes and decreased laterality (left minus right of metabolism in the anterior cingulate).

CONCLUSIONS

The neurobiology of depression in schizophrenia thus seems to share features with major depression due to other disease states.

A follow-up magnetic resonance imaging study of schizophrenia. Relationship of neuroanatomical changes to clinical and neurobehavioral measures

BACKGROUND

Cross-sectional neuroanatomical studies have reported abnormalities in schizophrenia that relate to disease variables. Longitudinal neuroimaging investigations that integrate anatomical, clinical, and neurobehavioral measures may help clarify the pathogenesis of schizophrenia.

METHODS

Magnetic resonance brain imaging and neurobehavioral studies were conducted at baseline and after 30.63 +/- 12.92 months (mean +/- SD) in 40 patients with schizophrenia (23 men and 17 women) and 17 healthy controls (13 men and 4 women). The schizophrenia group included 20 first-episode and 20 previously treated subjects. Volumes of whole-brain, cerebrospinal fluid, and frontal and temporal lobes were measured. The severity of negative and positive symptoms was assessed, medications were monitored, and neurobehavioral functioning in 8 domains was evaluated.

RESULTS

Both first-episode and previously treated patients had smaller brains and frontal and temporal lobes than controls at intake. Longitudinally, reduction in frontal lobe volume was found only in patients, whereas temporal lobe reduction was also seen in controls. The association between volume reduction and symptom changes differed between patient groups, but volume reduction was associated with decline in some neurobehavioral functions in both groups. Exploratory analysis suggested that neuroleptic dose is correlated with changes in all 3 domains.

CONCLUSIONS

The existence of neuroanatomical and neurobehavioral abnormalities in patients with first-episode schizophrenia indicates that the brain dysfunction occurred before clinical presentation. However, there is also evidence of progression, in which anatomical changes may affect some clinical and neurobehavioral features of the illness in some patients.

Depression in schizophrenia: I. Association with neuropsychological deficits

BACKGROUND

The presence of depression in schizophrenia has been well described with regard to stage and symptoms of illness; however, little is known about the possible etiology.

METHODS

In an effort to advance the understanding of the neurobiology of depression in schizophrenia, we grouped patients with schizophrenia based on their ratings on the 21-item Hamilton Depression Rating Scale. There were 63 patients (35 men, 28 women) in the high (> or = 18) depression group and 81 patients (52 men, 29 women) in the low (< 18) depression group. The groups were compared in demographic, clinical, and eight neuropsychological domains.

RESULTS

The two groups differed in age at onset of illness, severity of delusions, and performance in a single neuropsychological domain: attention. The specific component of impaired attention was vigilance, with poorest performance seen in women with higher depression scores.

CONCLUSION

The presence of specific attentional impairment associated with depressive symptoms in schizophrenia is consistent with the hypothesis of frontal lobe dysfunction in depression, because these regions have been implicated in attentional processes.

Effect of very high single dose of cisplatinum and of radiation on the brain of the rabbit

The importance of chemotherapy and radiotherapy for treating brain tumors, is well established. In a previous study, a rabbit's brain was treated with doses of up to 12 mg kg-1 of cisplatinum and 4000 cGy, without any morphological or pathological changes. The purpose of this study is to establish the effect of very high single doses of cisplatinum and radiation on the rabbit's brain, applied in 12, 16 and 18 mg kg-1, and 5000, 7500 and 8000 cGy, respectively. The general clinical and neurological condition of the rabbits was unaffected, but areas of alopecia and scalp ulcers appeared. Although these are very high doses of chemotherapy and radiotherapy, the histopathological and morphological examination of the rabbit's brain remained normal.

Functional MRI reveals left amygdala activation during emotion

The potential of functional magnetic resonance imaging (fMRI) for experimental studies of the brain and behavior considerable given its superior time and spatial resolution, but few studies have attempted to validate them against established methods for measuring cerebral activation. In a previous study absolute regional cerebral blood flow was measured in 16 healthy individuals using quantitative H215O-PET during standardized happy and sad mood induction and during two non-emotional control conditions. During sad mood, blood flow increased in the left amygdala and these changes correlated with shifts towards a negative affect. In the present study blood oxygenation level dependent (BOLD) changes were measured with fMRI during the same experimentally controlled mood states and control tasks. Twelve right-handed normal subjects were examined with a T2*-weighted FLASH sequence. A significant increase in signal intensity was found during sad as well as happy mood induction in the left amygdala. This converging evidence supports the potential of fMRI for advancing the understanding of neural substrates for emotional experience in humans.

Olfactory identification deficits in schizophrenia: correlation with duration of illness

OBJECTIVE

The authors examined the relationship between deficits in olfactory identification and duration of illness in young and elderly patients with schizophrenia.

METHOD

Olfactory identification performance of 38 patients with schizophrenia and 40 normal subjects was compared by using the University of Pennsylvania Smell Identification Test.

RESULTS

The schizophrenic patients demonstrated olfactory deficits relative to the comparison group, and the elderly schizophrenic patients displayed a greater magnitude of olfactory deficit than the younger patients. Independent of normal aging effects and cognitive deficit, patients with schizophrenia showed a strong relationship between olfactory identification scores and duration of illness, which suggests that olfactory abilities decline progressively over the course of the disorder.

CONCLUSIONS

In contrast to other neuropsychological measures that have been reported to be stable over the course of illness, olfactory identification abilities deteriorate steadily in patients with schizophrenia, even for those with relatively recent onset.

Effects of aging on the cerebral distribution of technetium-99m hexamethylpropylene amine oxime in healthy humans

Some brain functions decline at a linear rate throughout adulthood. Others remain relatively stable until very late in the life cycle. This study characterized the effects of aging on the regional cerebral distribution of hexamethylpropylene amine oxime (HMPAO) in healthy human volunteers. The sample consisted of 26 men and 18 women with a mean age of 41.6+/-14.9 years (range: 19-73). Their past medical histories, physical examinations, and laboratory screening tests were normal. Single-photon emission tomography (SPET) scans of the brain were performed with a standardized acquisition and processing protocol on a triple-headed camera equipped with fan beam collimators. A 3-D restorative filter and a correction for uniform attenuation were applied before the images were reinterpolated in planes parallel to the line connecting the frontal and occipital poles. Mean counts per pixel were measured in multiple regions of interest (ROIs) within each hemisphere by custom fitting a set of templates to the images. The mean activity in each ROI was compared with the mean activity per pixel in the whole brain. Regression analyses were used to relate the activity ratios to age with both linear and nonlinear models. The relative concentration of radioactivity decreased significantly with age in most, but not all, gray matter structures. It increased in the white matter regions. The nonlinear model of aging fit the data significantly better than a straight line did. Most of the changes with age occurred during young adulthood. No further changes were detectable after the onset of middle age. The median breakpoint age at which the rate of change became negligible was 36.6 years. Aging significantly affects the relative uptake of HMPAO in healthy humans. It decreases in many gray matter regions and increases in most white matter regions. However, the changes do not appear to be linear. Most seem to occur during young adulthood before people reach their late thirties. The distribution then appears to remain relatively stable throughout middle age.

PET regional cerebral blood flow change during working and declarative memory: relationship with task performance

Functional and anatomical relationships between working and declarative memory were investigated by contrasting regional cerebral blood flow (rCBF) change during standard working (Wisconsin Card Sorting Test, WCST) and declarative memory (Paired Associate Recognition Test, PART) tasks using identical stimulus-response modalities. The tasks and a resting baseline were administered to 30 participants (16 men, 14 women) during successive 10-min positron emission tomography 15O-water measures of rCBF. For both tasks, rCBF increased over baseline in inferior frontal and occipitotemporal regions, with more consistent dorsolateral prefrontal activation for WCST than PART. Additional orbitofrontal increases and dorsomedial decreases were seen for the PART. Activation patterns diverged when performance was considered. For the WCST, high performers activated dorsolateral and inferior frontal regions, whereas top PART performers activated only the occipitotemporal region. These results suggest operation of a frontotemporal network subserving both types of memory function that becomes more focal as performance increases.

Attentional dysfunctions in neuroleptic-naive and neuroleptic-withdrawn schizophrenic patients and their siblings

This study examined attentional deficits in 44 schizophrenic patients (24 neuroleptic-naive and 20 neuroleptic-withdrawn patients) across changes in medication status and clinical state using a 1-9 continuous performance test (CPT) with distractors. Patients' attentional selectivity scores (A') were unchanged from the off-medication to on-medication testings (on average, 6 months later), despite significant improvement in both positive and negative symptoms. Both patient groups had significantly lower A' scores than 44 matched healthy controls at each testing. The nonschizophrenic siblings (n = 15) of these patients made significantly more errors of omission and commission than healthy controls. The results suggest that attentional deficits, as measured by this CPT, appear to measure stable markers of schizophrenia that may be associated with genetic vulnerability to the illness.

Attentional dysfunctions in neuroleptic-naive and neuroleptic-withdrawn schizophrenic patients and their siblings

This study examined attentional deficits in 44 schizophrenic patients (24 neuroleptic-naive and 20 neuroleptic-withdrawn patients) across changes in medication status and clinical state using a 1-9 continuous performance test (CPT) with distractors. Patients' attentional selectivity scores (A') were unchanged from the off-medication to on-medication testings (on average, 6 months later), despite significant improvement in both positive and negative symptoms. Both patient groups had significantly lower A' scores than 44 matched healthy controls at each testing. The nonschizophrenic siblings (n = 15) of these patients made significantly more errors of omission and commission than healthy controls. The results suggest that attentional deficits, as measured by this CPT, appear to measure stable markers of schizophrenia that may be associated with genetic vulnerability to the illness.

Neuropsychological evidence supporting a neurodevelopmental model of schizophrenia: a longitudinal study

The stability of neuropsychological performance in schizophrenia and its relationship to clinical change was contrasted between 60 patients with schizophrenia (30 first-episode, 30 previously treated) and 38 healthy controls using a comprehensive neuropsychological battery and clinical scales administered at intake and at a 19-month follow-up. Consistent with the neurodevelopmental model of schizophrenia, patients demonstrated deficits in cognitive performance at initial testing and did not show decline at follow-up. There were no differences in neuropsychological performance over time between first-episode and previously treated patients, nor between male and female patients or controls. As expected, patients improved clinically with treatment with respect to both positive and negative symptoms. First-episode patients improved more on the positive symptoms of hallucination and delusion; male and female patients showed equivalent clinical improvement. Clinical improvement correlated positively with neuropsychological change, with improved negative symptomatology accounting for most of the significant correlations.

Lateralized changes in regional cerebral blood flow during performance of verbal and facial recognition tasks: correlations with performance and "effort"

Functional neuroimaging has been used to investigate neural substrates of mnemonic processes, and cerebral blood flow (CBF) measures have been sensitive to activation with memory tasks. Studies of memory with two-dimensional 133Xenon clearance techniques found that word and face recognition tasks produced contralateral CBF changes in mid-temporal cortical regions. This study replicated the activation paradigm, expanding to the three-dimensional resolution of positron emission tomography (PET). Word and face recognition, and a control baseline task were administered to 19 healthy right-handed volunteers (11 men, 8 women) during successive 10 min PET 15O-water measures of CBF. Quantitative CBF rates were calculated with the arterial input function and the equilibrium model. Redistributions of blood flow were compared across tasks-using both absolute and relative (region/ whole brain) CBF. Replicating the 133Xenon clearance findings, CBF was "appropriately" lateralized during task performance (left-right for words > left-right for faces) in the mid-temporal region. Contrary to predictions, the recognition tasks did not activate expected mesolimbic or prefrontal areas. The task-induced CBF changes also correlated with performance. Bilateral CBF in mid-temporal and parahippocampal gyrus regions of interest correlated with the ability to correctly identify word targets (sensitivity). Left-lateralized CBF in the amygdala and hippocampus correlated with better word sensitivity as well as specificity (ability to correctly reject foils). Complementally, right-lateralized CBF in the parahippocampal gyrus correlated with better face specificity performance. In addition, left-lateralized CBF in the amygdala and right-lateralized CBF in the parahippocampal gyrus and hippocampus correlated with "mental effort" indices (task performance relative to basal ability) for word and face memory tasks, respectively. Thus, whereas this recognition task showed the expected lateralized increase in the mid-temporal region and not in frontal and limbic areas, lateralized activation in some of these areas was associated with better performance. Exploratory analyses on other regions showed lateralized changes in one additional temporal region, the occipital-temporal, and several limbic regions.

Effect of high simple dose of cisplatinum and of radiation on the brain of rabbit

In former studies of intracarotid and intravenous administration of cisplatinum, separate and combined with brain irradiation, we found no cerebral damage. In this study, gradually increasing high doses (above the therapeutic ones) of cisplatinum were administered intravenously to one series of rabbits and increasing high amounts of irradiation (above the therapeutic amounts) were given to another series. Although the rabbits that received highest doses of irradiation developed areas of alopecia and skin ulcers on the head, the general clinical and histopathologic examination of the rabbits' brains in both series was normal. The purpose of this study was to establish the effects of high doses of intravenous cisplatinum and irradiation on the rabbits brains.

PET regional cerebral blood flow change during working and declarative memory: relationship with task performance

Functional and anatomical relationships between working and declarative memory were investigated by contrasting regional cerebral blood flow (rCBF) change during standard working (Wisconsin Card Sorting Test, WCST) and declarative memory (Paired Associate Recognition Test, PART) tasks using identical stimulus-response modalities. The tasks and a resting baseline were administered to 30 participants (16 men, 14 women) during successive 10-min positron emission tomography 15O-water measures of rCBF. For both tasks, rCBF increased over baseline in inferior frontal and occipitotemporal regions, with more consistent dorsolateral prefrontal activation for WCST than PART. Additional orbitofrontal increases and dorsomedial decreases were seen for the PART. Activation patterns diverged when performance was considered. For the WCST, high performers activated dorsolateral and inferior frontal regions, whereas top PART performers activated only the occipitotemporal region. These results suggest operation of a frontotemporal network subserving both types of memory function that becomes more focal as performance increases.