Response Rate and Molecular Correlates to Encorafenib and Binimetinib in BRAF-V600E Mutant High-Grade Glioma

PURPOSE

Although fewer than 5% of high-grade gliomas (HGG) are BRAF-V600E mutated, these tumors are notable as BRAF-targeted therapy shows efficacy for some populations. The purpose of this study was to evaluate response to the combination of encorafenib with binimetinib in adults with recurrent BRAF-V600-mutated HGG.

PATIENTS AND METHODS

In this phase 2, open-label, Adult Brain Tumor Consortium (ABTC) trial (NCT03973918), encorafenib and binimetinib were administered at their FDA-approved doses continuously in 28-day cycles. Eligible patients were required to have HGG or glioblastoma with a BRAF-V600E alteration that was recurrent following at least one line of therapy, including radiotherapy.

RESULTS

Five patients enrolled between January 2020 and administrative termination in November 2021 (due to closure of the ABTC). Enrolled patients received treatment for 2 to 40 months; currently one patient remains on treatment. Centrally determined radiographic response rate was 60%, with one complete response and two partial responses. Methylation profiling revealed that all tumors cluster most closely with anaplastic pleomorphic xanthoastrocytoma (PXA). Transcriptional profile for MAPK-response signature was similar across all tumors at baseline and did not correlate with response in this small population. Circulating tumor DNA measured in plasma samples before treatment, during response, and upon progression showed feasibility of detection for the BRAF-V600E alteration. No new safety signal was detected.

CONCLUSIONS

Encorafenib and binimetinib exhibit positive tumor responses in patients with recurrent BRAF-V600E mutant HGG in this small series, warranting therapeutic consideration. Although toxicity remains a concern for BRAF-targeted therapies, no new safety signal was observed in these patients.

Phase I dose-escalation study of procaspase-activating compound-1 in combination with temozolomide in patients with recurrent high-grade astrocytomas

BACKGROUND

Procaspase-3 (PC-3) is overexpressed in various tumor types, including gliomas. Targeted PC-3 activation combined with chemotherapy is a novel strategy for treating patients with high-grade gliomas, with promising preclinical activity. This study aimed to define safety and tolerability of procaspase-activating compound-1 (PAC-1) in combination with temozolomide (TMZ) for patients with recurrent high-grade astrocytomas.

METHODS

A modified-Fibonacci dose-escalation 3 + 3 design was used. PAC-1 was administered at increasing dose levels (DL; DL1 = 375 mg) on days 1-21, in combination with TMZ 150 mg/m2/5 days, per 28-day cycle. Dose-limiting toxicity was assessed during the first 2 cycles. Neurocognitive function (NCF) testing was conducted throughout the study.

RESULTS

Eighteen patients were enrolled (13 GBM, IDH-wild type; 2 astrocytoma, IDH-mutant, grade 3; 3 astrocytoma, IDH-mutant, grade 4). Dose escalation was discontinued after DL3 (ie, PAC-1, 625 mg) due to lack of additional funding. Grade 3 toxicity was observed in 1 patient at DL1 (elevated liver transaminases) and 1 at DL 2 (headache). Two partial responses were observed at DL1 in patients with GBM, O6-methylguanine-DNA methyltransferase (MGMT) promoter methylated. Two patients had stable disease, and 11 experienced progression. NCF testing did not show a clear relationship between PAC-1 dose, treatment duration, and declines in NCF.

CONCLUSIONS

Combination of PAC-1 and TMZ was well tolerated up to 625 mg orally daily and TMZ orally 150 mg/m2/5 days per 28-day cycle. The maximum tolerated dose was not reached. Further dose escalation of PAC-1 in combination with TMZ is advised before conducting a formal prospective efficacy study in this patient population.

Functional coupling of parietal α rhythms is enhanced in athletes before visuomotor performance: a coherence electroencephalographic study

It has been shown that elite pistol shooters are characterized by a power increase of wide cortical electroencephalographic (EEG) alpha (about 8-12 Hz) and beta (about 14-35 Hz) rhythms during the preparation of air pistol shots, possibly related to selective attentional and "neural efficiency" processes [Del Percio C, Babiloni C, Bertollo M, Marzano N, Iacoboni M, Infarinato F, Lizio R, Stocchi M, Robazza C, Cibelli G, Comani S, Eusebi F (2009a) Hum Brain Mapp 30(11):3527-3540; Del Percio C, Babiloni C, Marzano N, Iacoboni M, Infarinato F, Vecchio F, Lizio R, Aschieri P, Fiore A, Toràn G, Gallamini M, Baratto M, Eusebi F (2009b) Brain Res Bull 79(3-4):193-200]. Here, we tested the hypothesis that such processes are associated with an enhanced functional coupling of posterior cortical regions involved in task-relevant attentional processes and visuo-motor transformations. To this aim, between-electrodes spectral coherence was computed from spatially enhanced EEG data collected during a previous study (i.e. right handed 18 elite air pistol shooters and 10 matched non-athletes; augmented 10-20 system; surface Laplacian estimation). Theta (about 4-6 Hz), low-frequency alpha (about 8-10 Hz), high-frequency alpha (about 10-12 Hz), low-frequency beta (14-22 Hz), high-frequency beta (23-35 Hz), and gamma (36-44 Hz) bands were considered. Statistical results showed that intra-hemispheric low-frequency alpha (parietal-temporal and parietal-occipital regions), high-frequency alpha (parietal-temporal and parietal-occipital regions), high-frequency beta, and gamma (parietal-temporal regions) coherence values were stable in amplitude in the elite athletes but not in the non-athletes during the preparation of pistol shots. The same applies to inter-hemispheric low-frequency alpha (parietal regions), high-frequency alpha (parietal regions), high-frequency beta and gamma coherence values. These findings suggest that under the present experimental conditions, elite athletes are characterized by the stabilization of functional coupling of preparatory EEG rhythms between "visuo-spatial" parietal area and other posterior cortical areas.

Effects of tiredness on visuo-spatial attention processes in elite karate athletes and non-athletes

"Attentional" adaptations are fundamental effects for sport performance. We tested the hypothesis that tiredness and muscular fatigue poorly affect visuo-spatial attentional processes in elite karate athletes. To this aim, 14 elite karate athletes and 11 non-athletes were involved in an isometric contraction exercise protocol up to muscular fatigue. Blood lactate and attention measurements were taken. Posner's test probed "endogenous" (i.e., internally planned allocation of spatial attention) and "reflexive" (i.e., brisk variation of endogenous spatial attention due to unexpected external stimuli) attention. Lactate and attentional measurements were performed before (Block 1, B1) and after the fatiguing exercise (B2) and at the end of a recovery period (B3). Compared to the non-athletes, the athletes showed a better performance in the fatigue protocol, confirmed by the higher absolute lactate values in B2. The correct responses in the "valid trials" probing "endogenous" attention were 92.4% (B1), 93.9% (B2), and 95.8% (B3) in the non-athletes, and 98.5%, 96.4%, 95.5% in the elite karate athletes. The correct responses in the "invalid trials" probing "reflexive" attention were 95.4%, 89.7%, 93.2% in the non-athletes, and 96.4%, 97.3%, 98.5% in the elite karate athletes. The percentage of correct responses in the "invalid" trials significantly decreased from B1 to B2 in the non-athletes but not in the elite karate athletes. In conclusion, tiredness and muscular fatigue do not affect "reflexive" attentional processes of elite karate athletes, which is crucial to contrast attacks coming from an unexpected spatial region.

Reafferent copies of imitated actions in the right superior temporal cortex

Imitation is a complex phenomenon, the neural mechanisms of which are still largely unknown. When individuals imitate an action that already is present in their motor repertoire, a mechanism matching the observed action onto an internal motor representation of that action should suffice for the purpose. When one has to copy a new action, however, or to adjust an action present in one's motor repertoire to a different observed action, an additional mechanism is needed that allows the observer to compare the action made by another individual with the sensory consequences of the same action made by himself. Previous experiments have shown that a mechanism that directly matches observed actions on their motor counterparts exists in the premotor cortex of monkeys and humans. Here we report the results of functional magnetic resonance experiments, suggesting that in the superior temporal sulcus, a higher order visual region, there is a sector that becomes active both during hand action observation and during imitation even in the absence of direct vision of the imitator's hand. The motor-related activity is greater during imitation than during control motor tasks. This newly identified region has all the requisites for being the region at which the observed actions, and the reafferent motor-related copies of actions made by the imitator, interact.

A four-dimensional probabilistic atlas of the human brain

The authors describe the development of a four-dimensional atlas and reference system that includes both macroscopic and microscopic information on structure and function of the human brain in persons between the ages of 18 and 90 years. Given the presumed large but previously unquantified degree of structural and functional variance among normal persons in the human population, the basis for this atlas and reference system is probabilistic. Through the efforts of the International Consortium for Brain Mapping (ICBM), 7,000 subjects will be included in the initial phase of database and atlas development. For each subject, detailed demographic, clinical, behavioral, and imaging information is being collected. In addition, 5,800 subjects will contribute DNA for the purpose of determining genotype- phenotype-behavioral correlations. The process of developing the strategies, algorithms, data collection methods, validation approaches, database structures, and distribution of results is described in this report. Examples of applications of the approach are described for the normal brain in both adults and children as well as in patients with schizophrenia. This project should provide new insights into the relationship between microscopic and macroscopic structure and function in the human brain and should have important implications in basic neuroscience, clinical diagnostics, and cerebral disorders.

Experience-dependent modulation of motor corticospinal excitability during action observation

The primate premotor cortex is endowed with an "action observation/execution matching system", that is, the same premotor neurons discharge when actions are performed and when actions are observed. Hence, this system predicts a strong visual input to the motor system. Whether this input is dependent on visual experience or not has not been previously investigated. To address this issue we compared corticospinal excitability while subjects viewed frequently observed and less frequently observed hand actions of others and of themselves. Motor corticospinal excitability was larger when the action orientations were as they are frequently observed (Self-away, subject's own hand facing out from the subject, or Other-toward, an unknown hand facing toward the subject) compared with less frequently observed actions (Self-toward, subject's own hand facing "toward" the subject, or Other-away, an unknown hand facing out from the subject). This finding suggests that the modulation of motor corticospinal excitability during action observation and hence the "action observation/execution matching system" is largely dependent upon visual experience.

A probabilistic atlas and reference system for the human brain: International Consortium for Brain Mapping (ICBM)

Motivated by the vast amount of information that is rapidly accumulating about the human brain in digital form, we embarked upon a program in 1992 to develop a four-dimensional probabilistic atlas and reference system for the human brain. Through an International Consortium for Brain Mapping (ICBM) a dataset is being collected that includes 7000 subjects between the ages of eighteen and ninety years and including 342 mono- and dizygotic twins. Data on each subject includes detailed demographic, clinical, behavioural and imaging information. DNA has been collected for genotyping from 5800 subjects. A component of the programme uses post-mortem tissue to determine the probabilistic distribution of microscopic cyto- and chemoarchitectural regions in the human brain. This, combined with macroscopic information about structure and function derived from subjects in vivo, provides the first large scale opportunity to gain meaningful insights into the concordance or discordance in micro- and macroscopic structure and function. The philosophy, strategy, algorithm development, data acquisition techniques and validation methods are described in this report along with database structures. Examples of results are described for the normal adult human brain as well as examples in patients with Alzheimer's disease and multiple sclerosis. The ability to quantify the variance of the human brain as a function of age in a large population of subjects for whom data is also available about their genetic composition and behaviour will allow for the first assessment of cerebral genotype-phenotype-behavioural correlations in humans to take place in a population this large. This approach and its application should provide new insights and opportunities for investigators interested in basic neuroscience, clinical diagnostics and the evaluation of neuropsychiatric disorders in patients.

Synthetic brain imaging: grasping, mirror neurons and imitation

The article contributes to the quest to relate global data on brain and behavior (e.g. from PET, Positron Emission Tomography, and fMRI. functional Magnetic Resonance Imaging) to the underpinning neural networks. Models tied to human brain imaging data often focus on a few "boxes" based on brain regions associated with exceptionally high blood flow, rather than analyzing the cooperative computation of multiple brain regions. For analysis directly at the level of such data, a schema-based model may be most appropriate. To further address neurophysiological data, the Synthetic PET imaging method uses computational models of biological neural circuitry based on animal data to predict and analyze the results of human PET studies. This technique makes use of the hypothesis that rCBF (regional cerebral blood flow) is correlated with the integrated synaptic activity in a localized brain region. We also describe the possible extension of the Synthetic PET method to fMRI. The second half of the paper then exemplifies this general research program with two case studies, one on visuo-motor processing for control of grasping (Section 3 in which the focus is on Synthetic PET) and the imitation of motor skills (Sections 4 and 5, with a focus on Synthetic fMRI). Our discussion of imitation pays particular attention to data on the mirror system in monkey (neural circuitry which allows the brain to recognize actions as well as execute them). Finally, Section 6 outlines the immense challenges in integrating models of different portions of the nervous system which address detailed neurophysiological data from studies of primates and other species; summarizes key issues for developing the methodology of Synthetic Brain Imaging; and shows how comparative neuroscience and evolutionary arguments will allow us to extend Synthetic Brain Imaging even to language and other cognitive functions for which few or no animal data are available.

Crossed-uncrossed difference in simple reaction times to lateralized flashes: between- and within-subjects variability

In unimanual reaction times (RT) to lateralized flashes, contralateral responses tend to be slower than ipsilateral responses. This has been called Crossed-Uncrossed Difference (CUD). The CUD tends to show variability across subjects and across studies, but until now the stability of the CUD in an individual subject has not been investigated. To address the role of inter- and intra-subject variability in the CUD, three normal right handers were tested over 50 experimental sessions of 800 trials each, for a total of 40,000 trials of simple reaction times to lateralized flashes. In each subject, CUDs were computed for each session, over two, three, or more sessions, and over the entire dataset. These CUDs were then compared to the CUDs obtained in a group of 15 normal right handers, each tested once in a single session. Results show that: (i) CUD variability across several sessions in a single subject mimics the variability observed in a sample of subjects tested in a single session; (ii) this variability is considerably reduced when the CUD is computed over at least 2400 trials per subject; (iii) CUDs computed over 2400 and up to 12,000 of trials tend to be extremely similar ( approximately 2 ms) across the three subjects tested here; (iv) when reaction times are ordered from the fastest to the slowest and divided into bins, the CUD is remarkably stable over the entire reaction time distribution; and (v) in contrast to the variability of the CUD, the variability for crossed and uncrossed responses across several sessions in a single subject is small and does not mimic the variability observed in a sample of subjects tested in a single session. Taken together, these data suggest that the intersubject variability in the CUD observed in single experimental sessions does not represent a reliable intersubject difference and that the CUD computed over thousands of trials reflects hard-wired mechanisms of callosal transmission.

Parallel visuomotor processing in the split brain: cortico-subcortical interactions

We tested nine patients with callosal pathology in a simple reaction time task with and without redundant targets in the same or opposite visual hemifield. Four patients showed large facilitation (redundancy gain) in the presence of a redundant target, exceeding probability summation models (neural summation). Five patients showed redundancy gain not exceeding probability models. Violation of probability models was not associated with a specific type of callosal lesion. Neural summation, which probably occurs at collicular level, may be modulated by cortical activity. To test this hypothesis, we used functional MRI. During detection of redundant simultaneous targets, activations in the extrastriate cortex were observed in a patient with callosal agenesis and redundancy gain violating probability models, but not in a patient with callosal agenesis and redundancy gain not exceeding probability models. We conclude that cortical activity in the extrastriate cortex may be a modulating factor in the magnitude of the redundancy gain during parallel visuomotor transforms.

Cortical mechanisms of human imitation

How does imitation occur? How can the motor plans necessary for imitating an action derive from the observation of that action? Imitation may be based on a mechanism directly matching the observed action onto an internal motor representation of that action ("direct matching hypothesis"). To test this hypothesis, normal human participants were asked to observe and imitate a finger movement and to perform the same movement after spatial or symbolic cues. Brain activity was measured with functional magnetic resonance imaging. If the direct matching hypothesis is correct, there should be areas that become active during finger movement, regardless of how it is evoked, and their activation should increase when the same movement is elicited by the observation of an identical movement made by another individual. Two areas with these properties were found in the left inferior frontal cortex (opercular region) and the rostral-most region of the right superior parietal lobule.

The crossed-uncrossed difference in simple reaction times to lateralized auditory stimuli is not a measure of interhemispheric transmission time: evidence from the split brain

In a complete commissurotomy patient, the difference in simple (detection) reaction times between responses to contralateral and ipsilateral auditory stimuli was found to be small (less than 5 ms) and not reliable, whereas the difference between contralateral and ipsilateral responses to lateralized visual stimuli was found to be large (ranging from 25 ms to 45 ms in different previous studies) and always reliable. This suggests that the reaction times difference in detecting lateralized auditory stimuli is not a valid estimate of interhemispheric transmission time.

Individual differences in the hemispheric specialization of dual route variables

The dual route model suggests that reading of letter strings can occur through both a lexical and a nonlexical route. Hemispheric specialization of these routes has also been posited, suggesting that the left hemisphere has both lexical and nonlexical routes while the right hemisphere has only a lexical route. However, some recent data conflict with this hemispheric dual route model, suggesting that both hemispheres may have access to both routes. The purpose of the present study was to investigate individual differences in the hemispheric specialization of these routes and to determine whether these group differences in their specialization might explain conflicts in the literature. The effect of four individual difference factors was explored: handedness, biological sex, menstrual stage (i.e., fluctuations in estrogen), and self-rated degree of masculinity (i.e., sexual attribution). We looked at the interaction of these individual differences with the following dual route variables: (i) string length, (ii) word frequency, (iii) regularity of grapheme-phoneme correspondences of words, and (iv) the interaction of frequency and regularity using a bilateral lexical decision task. We observed that sex, menstrual stage, and masculinity each affected hemispheric specialization of the dual route variables, but did so in different ways. We posit that both hemispheres have orthographical (lexical) access as well as phonological (nonlexical) access to words. Further, we suggest that the presence of phonological processing in the right hemisphere depends on available resources and the strategies used, which are subject to individual differences.

Emission tomography contribution to clinical neurology

The role of functional neuroimaging techniques in furthering the understanding of pathophysiological mechanisms of neurological diseases and in the assessment of neurological patients is increasingly important. Here, we review data mainly from emission tomography techniques, namely positron emission tomography (PET) and single photon emission computerized tomography (SPECT), that have helped elucidate the pathophysiology of a number of neurological diseases and have suggested strategies in the treatment of neurological patients. We also suggest possible future developments of functional neuroimaging applied to clinical populations and briefly touch on the emerging role of functional magnetic resonance imaging (fMRI) in clinical neurology and neurosurgery.

Bimodal (auditory and visual) left frontoparietal circuitry for sensorimotor integration and sensorimotor learning

We used PET to test whether human premotor and posterior parietal areas can subserve basic sensorimotor integration and sensorimotor learning equivalently in response to auditory and visual stimuli, as has been shown in frontoparietal neurons in non-human primates. Normal subjects were studied while they performed a spatial compatibility task. They were instructed to respond to lateralized auditory and visual stimuli with the ipsilateral hand (compatible condition) or with the contralateral hand (incompatible condition). Reaction times were faster in the compatible than in the incompatible condition, for both auditory and visual stimuli. Left rostral dorsal premotor and posterior parietal blood-flow increases were observed in the incompatible condition, compared with the compatible condition, for both auditory and visual modalities. Blood-flow increases, which were correlated with the reaction-time learning curves, were observed in both auditory and visual modalities in the left caudal dorsal premotor cortex. These data suggest that, as in non-human primates, human frontoparietal areas can subserve basic sensorimotor transformations equivalently in the auditory and visual modality. Further, they reveal a functional rostrocaudal fractionation of human dorsal premotor cortex that resembles the rostrocaudal anatomical and physiological fractionation observed in non-human primates.

Merging of oculomotor and somatomotor space coding in the human right precentral gyrus

Using PET and H215O, we investigated the cortical areas that merge two different ways of coding space in the cerebral cortex, those concerned with the oculomotor and the somatomotor space. Normal subjects performed a visuomotor task that required the spatial coding of visual stimuli in oculomotor space and of motor responses in somatomotor space. We manipulated the mapping of oculomotor and somatomotor space by instructing subjects to respond in half of the PET scans with uncrossed hands, i.e. each hand was in the homonymous hemispace (standard oculomotor-somatomotor mapping), and in the other half with crossed hands, i.e. with the left hand in the right hemispace and the right hand in the left hemispace (nonstandard oculomotor-somatomotor mapping). Reaction times were slower for crossed hands than uncrossed hands. Crossed hands produced increases in blood flow in the precentral and postcentral gyri of the right hemisphere. Increases in blood flow in the precentral gyrus were correlated with increases in reaction time comparing the crossed-hand task with the uncrossed one, whereas the increases in blood flow in the postcentral gyrus were not. These findings suggest that the right precentral gyrus merges oculomotor and somatomotor space coding in the human brain.

Does the previous trial affect lateralized lexical decision?

We investigated the effect of previous trial variables on performance in the current trial in a lexical decision task with unilateral presentation of one letter string or bilateral simultaneous presentation of two different letter strings, one cued to be processed (target) and the other uncued, to be ignored (distractor). The variables included correctness of the previous trial, visual hemifield and wordness of the previous trial, and presentation mode of the previous trial (unilateral or bilateral). An incorrect response on the previous trial enhanced the accuracy in the current trial only in the left visual field (LVF). A previous LVF target produced faster correct responses to LVF targets in the current trial and LVF word recognition was more accurate when the previous LVF target was a word rather than a nonword. Target processing in the current trial was not inhibited or facilitated if the target belonged to the same response category as the unattended stimulus in the previous trial (absence of "negative priming'). Taken together, our data suggest that previous trial effects in lateralized lexical decision are stronger for word decisions in the LVF, and may account for the inconsistency of the wordness effect in the LVF across different lateralized lexical decision experiments. Our data also suggest that behavioral laterality experiments are well advised to use random sequences that change across subjects in order to minimize previous trial effects.

Brain-behavior relationships: evidence from practice effects in spatial stimulus-response compatibility

1. We measured relative cerebral blood flow (rCBF) changes with positron emission tomography and H(2) 15O in six normal subjects repeatedly performing a spatial stimulus-response compatibility task. Subjects had two motor response conditions. They were instructed to respond with the left hand to a left visual field light stimulus and with the right hand to a right visual field light stimulus (compatible condition), and with the right hand to a left visual field light stimulus and with the left hand to a right visual field light stimulus (incompatible condition). Six rCBF measurements per condition were performed in each subject. 2. Reaction times were faster (P < 0.0005) in the compatible (287 ms) than the incompatible (339 ms) condition (spatial stimulus-response compatibility effect). A bilateral increase (P < 0.05) in rCBF in the superior parietal lobule of the two hemispheres was observed during the incompatible condition when compared with the compatible one. No rCBF decreases were observed. Reaction times correlated (P < 0.0001) with the rCBF in the two activated superior parietal lobule areas. 3. Reaction times decreased with practice according to a linear trend (P < 0.05). Practice-related linear rCBF increases (P < 0.05) were observed in the dorsolateral prefrontal, premotor, and primary motor cortex of the left hemisphere. No significant rCBF decreases were observed. 4. Practice did not affect the spatial stimulus-response compatibility effect. A parallel shortening of reaction times was observed in both compatible and incompatible conditions, in both left and right hand responses, and in both left and right visual fields. Accordingly, when rCBF was analyzed, the spatial stimulus-response compatibility by practice interaction did not show any significant activated area. 5. These findings suggest that the two activated areas in the left and right superior parietal lobules subserve the mapping of the visual stimulus spatial attributes onto the motor response spatial attributes and that the rCBF increases in the incompatible response condition represent the more complex computational remapping required when stimuli and response do not match spatially. 6. The dorsolateral prefrontal, premotor, and motor rCBF linear increases in the left hemisphere seem to reflect the effect of practice on cortical processes common to both compatible and incompatible response conditions. These cortical processes presumably strengthen the links between stimuli and responses under different stimulus-response compatibility conditions. The lateralization of the rCBF increases suggests a left hemisphere superiority in these processes.

Hemispheric independence in word recognition: evidence from unilateral and bilateral presentations

We compared behavioral laterality effects in a lexical decision task using cued unilateral or bilateral presentations of different stimuli to normal subjects. The goals were to determine the effects of lexical variables on word recognition in each hemisphere under conditions of maximal independence of information processing in the two hemispheres and to assess the degree of residual interhemispheric effects that can still exist then. Bilateral presentations increased hemispheric independence in word recognition, indexed by a significant interaction of response hand with target visual field. Bilateral presentations also selectively impaired word decisions, suggesting that word processing benefits from interhemispheric interactions, whereas nonword processing is done independently in each hemisphere. Indeed, there was a significant congruity effect for word targets only, whereby the wordness of the unattended stimulus affected the speed of processing of attended word targets. Word frequency and regularity affected both hemispheres equally, arguing against the hemispheric interpretation on the dual route model of word recognition. Length affected the processing of nonwords more than words and in the left visual field more than in the right visual field. Taken together, the data support the conclusion that each normal hemisphere can control word recognition independently of the other.

Patterns of neuropsychological impairment in mild dementia: a comparison between Alzheimer's disease and multi-infarct dementia

The objective was to investigate the clinical and psychometric differences between patients with dementia of Alzheimer type (DAT) and patients with multi-infarct dementia (MID), matched for age, sex, education, and severity. Sixteen patients with DAT, 16 patients with MID, and 30 healthy individuals, were drawn from a longitudinal study on aging and dementia. Subjects with medical or previous mental disorders were excluded. DAT and controls with focal brain abnormalities on magnetic resonance imaging (MRI) were excluded. Diagnosis of dementia was carried out according to DSM-III-R criteria. Dementia severity was staged using the Clinical Dementia Rating (CDR) scale, and only patients with a score of 0.5-1 on CDR were studied. The main outcome measures were quantitative clinical scales of the assessment of global mental status, depression and anxiety, as well as a wide battery of neuropsychological tests for the evaluation of executive/conceptual functions and memory, as well as attention verbal ability, and visuospatial skill functions. The performance of demented patients compared to normal controls was affected on all measurements except for depression and anxiety. DAT patients showed compared to MID patients a greater extent of impairment on tasks assessing verbal comprehension and memory while MID patients were more significantly impaired on measures of frontal lobe functioning. Clinically matched DAT and MID patients show a differential pattern of neuropsychological impairment when studied in an early stage of dementia and with a mild degree of severity. Such patterns might be of value for the development of clinical diagnostic criteria.

Channels of the corpus callosum. Evidence from simple reaction times to lateralized flashes in the normal and the split brain

We studied 75 normal subjects and three commissurotomized patients using unimanual simple reaction times to lateralized flashes as a behavioural estimate of interhemispheric transmission time. Three different versions of the paradigm were performed: (i) the basic task; (ii) a motor task, with an increased complexity of the motor response; and (iii) a visual task, with an increased complexity of the visual stimulus presentation. We tested two hypotheses. First, that the new versions of the simple reaction time task result in shifts in hemispheric specialization for processing motor output (indicated by a main effect of response hand) or visual input (indicated by a main effect of visual field) alone, without affecting callosal transmission. In that case normals and split brain patients would show no significant task by response hand by visual field interaction and no significant task by crossed-uncrossed difference interaction. Secondly, that the new versions of the task affect callosal transfer. In that case, normals, but not split brain patients, would show a significant task by response hand by visual field interaction and a significant task by crossed-uncrossed difference interaction. Results are consistent with the latter hypothesis, showing that the motor task significantly changed the response hand by visual field interaction and the crossed-uncrossed difference, but only in normal subjects, perhaps producing a switch in the callosal channel subserving the interhemispheric transfer.

Post-stroke depression: relationships with morphological damage and cognition over time

The aim of the present study was to investigate the relationships between post-stroke depression (PSD), lesion location and cognitive deficits after stroke. We studied 20 patients within the first month after clinical onset (T1), and one year later (T2). PSD was observed in 55% of patients at T1 and 35% of patients at T2. At T1, depression was reliably correlated with dorsal lesions in the right-hemisphere and anterior lesions in the left hemisphere. Lesion location was no longer a significant factor determining PSD at T2. Changes in PSD, from T1 to T2, were inversely correlated with the performances in cognitive tests exploring the domains of attention, visuospatial learning, executive/motor functions, and with the global composite cognitive score. Our data suggest that: 1) in the mix of influences that may produce PSD, lesion location is the main factor determining mood changes after stroke in the first month; 2) PSD produces deficits in attention, learning, and executive/motor functions, without affecting language and other cognitive domains.

Alien hand syndrome: interhemispheric motor disconnection due to a lesion in the midbody of the corpus callosum

The neuroanatomic substrate of the alien hand syndrome has remained controversial due to the noncircumscribed nature of cerebral injuries present in most cases. There have been few cases studied in which damage was restricted to portions of the body of the callosum, and most of those involved surgical callosotomy for tumors or epilepsy. We report the case of a woman with a transient alien hand syndrome caused by a stroke limited to the middle and posterior portions of the body of the corpus callosum. This case provides supportive evidence for damage to the midbody of the corpus callosum as the anatomic basis of nondominant alien hand syndrome and conforms to a model of interhemispheric motor disconnection as the essential component of this unusual behavioral syndrome. This disconnection can occur with injuries involving interhemispheric premotor and motor fibers traveling in the midportion of the callosum in individuals with left hemisphere dominance for motor activities.

Callosal transmission time before and after partial commissurotomy

Interhemispheric transmission time was measured in a patient, before and after partial commissurotomy sparing the splenium of the corpus callosum, using a simple reaction time paradigm with unimanual responses to lateralized flashes at 4 degrees and 8 degrees of eccentricity. Post-operative transfer time was longer than pre-operative transfer time at 8 degrees but not at 4 degrees of eccentricity. These data do not support the notion that the callosal transfer time is always faster through motor rather than visual fibers. They rather suggest that the callosal transfer time through visual fibers is longer than the callosal transfer time through motor fibers only for flashes at large eccentricities.

Reversed laterality of cerebral functions in a non-right-hander: neuropsychological and spect findings in a case of 'atypical' dominance

A 54-year-old non-right-handed man with positive familial sinistrality showed a pure right hemisphere syndrome following a left hemisphere stroke. Severe right side hemineglect, transcortical motor dysprosodia, spatial dysgraphia and visuo-constructive impairments were observed. At no time were the expected left hemisphere abnormalities such as aphasia, alexia, right-left disorientation or finger agnosia noted. A left fronto-temporal subcortical lesion was documented on CT scan. A Tc-99m HM-PAO SPECT study revealed no cerebral blood flow changes in the right hemisphere while in the left hemisphere a fronto-temporo-parietal cerebral blood flow reduction was evident. This case of a complete reversed laterality of cognitive functions argues for a distinction to be made between 'anomalous' cerebral dominance and 'atypical' cerebral dominance.

[Brain protection in heart surgery]

We investigated the effect of CDP-choline on brain protection during extra-corporeal circulation (ECC) in patients submitted to open-heart surgery. We studied forty patients, using neurological, neuropsychological, neuroradiological (CT scan), and CBF evaluations. All the patients were evaluated two weeks before (T1), two weeks (T2), one month (T3) and six months after surgery (T4). Patients were randomly divided into two groups: subjects of the first group were treated with 2000 mg/die e.v. from two weeks before surgery to ten days after surgery, and then with 1000 mg/die i.m., 15 days per month, for the following 6 months (Group A), while subjects of the second group were treated with 100 mg/die, from two weeks before surgery to six months after surgery (Group B). After surgery, neither neurological symptoms nor morphostructural lesions were observed in the two groups. However, in the Group A, 75% (15 out of 20) of the patients evidenced reduced performances on neuropsychological tests at T2, compared to T1. At T4 only 66% (10 out of 15) of the impaired patients showed a persistence of the deficit. In the Group B 70% (14 out of 20) of the patients displayed reduced performances at T2. At T4, almost all of the patients, namely 86% (12 out of 14), showed a persistence of neuropsychological deficits. CBF data showed hypoperfusion areas in 9 patients in Group A (1.7 +/- 4.15 mean areas per patient), and in 10 patients in Group B (3.33 +/- 1.3 mean areas per patient), at T2. In 2.2+ off