Comatose With Basilar Artery Occlusion: Still Odds of Favorable Outcome With Recanalization Therapy.

Background: Around 30-60% of patients with basilar artery occlusion (BAO) present with coma, which is often considered as a hallmark of poor prognosis. Aim: To examine factors that will help predict outcomes in patients with BAO comatose on admission. Methods: A total of 312 patients with angiography-proven BAO were analyzed. Comas were assessed as Glasgow Coma Scale (GCS) of ≤8 or impaired level of consciousness ascertained in the medical records. Outcomes were evaluated with the modified Rankin Scale (mRS) over a phone call at 3 months. In our study, 53 patients were excluded due to inadequate data on the level of consciousness. Results: In total, 103/259 (39.8%) of BAO patients were comatose on admission. Factors associated with acute coma were higher age, coronary artery disease, convulsions, extent of early ischemia by posterior circulation Acute Stroke Prognosis Early CT Score (pc-ASPECTS) < 8, absence of patent posterior collateral vasculature, and occlusion over multiple segments of BA. A total of 21/103 (20.4%) of comatose patients had a favorable outcome (mRS 0-3), and 12/103 (11.7%) had a good outcome (mRS 0-2). Factors associated with a favorable outcome in comatose BAO patients were younger age (p = 0.010), less extensive baseline ischemia (p = 0.027), recanalization (p = 0.013), and avoiding symptomatic intracranial hemorrhage (sICH) (p = 0.038). Factors associated with the poorest outcome or death (mRS 5-6) were older age (p = 0.001), diabetes (p = 0.022), atrial fibrillation (p = 0.016), lower median GCS [4 (IQR 3.6) vs. 6 (5-8); p = 0.006], pc-ASPECTS < 8 (p = 0.003), unsuccessful recanalization (p = 0.006), and sICH (p = 0.010). Futile recanalization (mRS 4-6) was significantly more common in comatose patients (49.4 vs. 18.5%, p < 0.001). Conclusions: One in five BAO patients with acute coma had a favorable outcome. Older patients with cardiovascular comorbidities and already existing ischemic lesions before reperfusion therapies tended to have a poor prognosis, especially if no recanalization is achieved and sICH occurred.

Outcomes and long-term mortality after basilar artery occlusion-A cohort with up to 20 years' follow-up.

BACKGROUND: The data on long-term outcome after basilar artery occlusion (BAO) are scarce. Little is known about BAO survivors´ outcome over decades. AIM: We set out to investigate long-term survival and causes of death in BAO patients with up to two decades of follow-up. We also evaluated differences in outcome trends. METHODS: Two hundred and seven BAO patients treated with intravenous thrombolysis (IVT) at the Department of Neurology, Helsinki University Hospital, between 1995 and 2016, were analyzed. Short-term outcome was assessed by modified Rankin Scale (mRS) at 3 months. Long-term cumulative survival rate was analyzed using Kaplan-Meier analysis. Factors associated with mortality were analyzed with Cox regression. RESULTS: Moderate outcome (mRS 0-3) was achieved in 41.1% and good outcome (mRS 0-2) in 30.4% of patients at 3 months. Three-month mortality was 39.6%, of which 89% died within the first month. The median follow-up time in 3-month survivors was 8.9 years (maximum 21.8 years). Total mortality during follow-up was 52.2%. Cumulative mortality rate was 25.7%. Older age, coronary artery disease and more extensive ischemic changes on admission brain imaging were independently associated with long-term mortality. After the acute phase, the rate of other vascular causes of death increased in relation to stroke. CONCLUSIONS: The described evolution of a large, single-center BAO cohort shows a trend towards a higher rate of good and/or moderate outcome during later years in IVT-treated patients. Survivors showed relative longevity, and the rate of cardiac and other vascular causes of death increased in relation to stroke sequelae over the long term.

Clinical and MRI Features of Cerebral Small-Vessel Disease in Type 1 Diabetes.

OBJECTIVE: To assess the prevalence of cerebral small-vessel disease (SVD) in subjects with type 1 diabetes compared with healthy control subjects and to characterize the diabetes-related factors associated with SVD. RESEARCH DESIGN AND METHODS: This substudy was cross-sectional in design and included 191 participants with type 1 diabetes and median age 40.0 years (interquartile range 33.0-45.1) and 30 healthy age- and sex-matched control subjects. All participants underwent clinical investigation and brain MRIs, assessed for cerebral SVD. RESULTS: Cerebral SVD was more common in participants with type 1 diabetes than in healthy control subjects: any marker 35% vs. 10% (P = 0.005), cerebral microbleeds (CMBs) 24% vs. 3.3% (P = 0.008), white matter hyperintensities 17% vs. 6.7% (P = 0.182), and lacunes 2.1% vs. 0% (P = 1.000). Presence of CMBs was independently associated with systolic blood pressure (odds ratio 1.03 [95% CI 1.00-1.05], P = 0.035). CONCLUSIONS: Cerebral SVD, CMBs in particular, is more common in young people with type 1 diabetes compared with healthy control subjects.

Sodium Channel SCN3A (NaV1.3) Regulation of Human Cerebral Cortical Folding and Oral Motor Development.

Channelopathies are disorders caused by abnormal ion channel function in differentiated excitable tissues. We discovered a unique neurodevelopmental channelopathy resulting from pathogenic variants in SCN3A, a gene encoding the voltage-gated sodium channel NaV1.3. Pathogenic NaV1.3 channels showed altered biophysical properties including increased persistent current. Remarkably, affected individuals showed disrupted folding (polymicrogyria) of the perisylvian cortex of the brain but did not typically exhibit epilepsy; they presented with prominent speech and oral motor dysfunction, implicating SCN3A in prenatal development of human cortical language areas. The development of this disorder parallels SCN3A expression, which we observed to be highest early in fetal cortical development in progenitor cells of the outer subventricular zone and cortical plate neurons and decreased postnatally, when SCN1A (NaV1.1) expression increased. Disrupted cerebral cortical folding and neuronal migration were recapitulated in ferrets expressing the mutant channel, underscoring the unexpected role of SCN3A in progenitor cells and migrating neurons.

Recanalization treatments in basilar artery occlusion-Systematic analysis.

BACKGROUND AND AIMS: Basilar artery occlusion is a most devastating form of stroke, and the current practice is to reverse it with revascularization therapies. Pharmacological thrombolysis, intravenous or intraarterial, has been adjuncted or replaced with invasive, endovascular thrombectomy procedures. The preferred approach remains unknown and many recanalizations are futile with no clinical benefit. We sought to determine reasons for futility and weigh the existing reports to find whether endovascular mechanical interventions provide superior outcomes over pharmacological thrombolysis alone. METHODS: After analyzing systematically the reports of outcomes produced by variable basilar artery occlusion recanalization protocols, information was retrieved and reconciled from 15 reports published from year 2005 comprising 803 patients in 17 cohorts. In the largest single-center cohort (162, Helsinki), predictors of futile recanalization (three-month modified Rankin Scale score 4 to 6) were determined. RESULTS: Good outcome was reported by mechanical approaches either alone or on demand more frequently than by pharmacological, intravenous or intraarterial thrombolysis protocols (35.5% versus 24.4%, p < 0.001), accompanied by higher recanalization rates (84.1% versus 70.9%, p < 0.001). Along with superior recanalization rate at 91%, good outcome was reached by primary thrombectomy in 36% at the cost of substantial futile recanalization rate at 60%, which was lower when using modern stentrievers only (52.8%). In the Helsinki cohort, the single most significant predictor was extensive baseline ischemia, increasing the odds of futility 20-fold (95%CI 4.39-92.29, p < 0.001). Other attributes of futility were ventilation support and history of atrial fibrillation or previous stroke. CONCLUSIONS: Endovascular mechanical approaches have been reported to provide superior outcomes over pharmacological thrombolysis in basilar artery occlusion. Stricter patient selection, most notably to exclude victims of already extended ischemia, would assist in translating excellent recanalization rates into improved clinical outcomes and more acceptable futility rates.

Helsinki experience on nonvitamin K oral anticoagulants for treating cervical artery dissection.

BACKGROUND: Cervical artery dissection (CeAD) patients with or without stroke are frequently treated with either antiplatelet agents or vitamin K antagonists (VKAs), but few data are reported on the use of nonvitamin K oral anticoagulants (NOACs). METHODS: Between November 2011 and January 2014, we recorded data from patients with a stroke due to vertebral (VAD) or internal carotid artery dissection (ICAD). Patients using oral anticoagulants were included in the study and were divided into two treatment groups: patients using NOACs and those using VKAs. Excellent outcome was defined on modified Rankin Scale (mRS) ≤1 at 6 months. RESULTS: Of 68 stroke patients (67% male; median age 45 [39-53]), six (8.8%; two with VAD and four with ICAD) were treated with NOACs: three with direct thrombin inhibitor dabigatran and three with direct factor Xa inhibitor rivaroxaban. National Institutes of Health Stroke Scale score at baseline was 4 (3-7) in the NOAC versus 2 (1-7) in the VKA groups. Complete recanalization at 6 months was seen in most patients in the NOAC (n = 5; 83%) and VKA (n = 34; 55%) groups. All the patients using NOACs had mRS ≤1 at 6 months and none had an intracerebral hemorrhage (ICH). In the VKA group most patients (n = 48; 77%) had mRS ≤1, one patient (1.7%) had an ICH and one died. CONCLUSIONS: In this small, consecutive single-center patient sample treating ischemic stroke patients with CeAD with NOACs did not bring up safety concerns and resulted in similar, good outcomes compared to patients using VKAs.

Brain activity during divided and selective attention to auditory and visual sentence comprehension tasks.

Using functional magnetic resonance imaging (fMRI), we measured brain activity of human participants while they performed a sentence congruence judgment task in either the visual or auditory modality separately, or in both modalities simultaneously. Significant performance decrements were observed when attention was divided between the two modalities compared with when one modality was selectively attended. Compared with selective attention (i.e., single tasking), divided attention (i.e., dual-tasking) did not recruit additional cortical regions, but resulted in increased activity in medial and lateral frontal regions which were also activated by the component tasks when performed separately. Areas involved in semantic language processing were revealed predominantly in the left lateral prefrontal cortex by contrasting incongruent with congruent sentences. These areas also showed significant activity increases during divided attention in relation to selective attention. In the sensory cortices, no crossmodal inhibition was observed during divided attention when compared with selective attention to one modality. Our results suggest that the observed performance decrements during dual-tasking are due to interference of the two tasks because they utilize the same part of the cortex. Moreover, semantic dual-tasking did not appear to recruit additional brain areas in comparison with single tasking, and no crossmodal inhibition was observed during intermodal divided attention.

Brain activations during bimodal dual tasks depend on the nature and combination of component tasks.

We used functional magnetic resonance imaging to investigate brain activations during nine different dual tasks in which the participants were required to simultaneously attend to concurrent streams of spoken syllables and written letters. They performed a phonological, spatial or "simple" (speaker-gender or font-shade) discrimination task within each modality. We expected to find activations associated specifically with dual tasking especially in the frontal and parietal cortices. However, no brain areas showed systematic dual task enhancements common for all dual tasks. Further analysis revealed that dual tasks including component tasks that were according to Baddeley's model "modality atypical," that is, the auditory spatial task or the visual phonological task, were not associated with enhanced frontal activity. In contrast, for other dual tasks, activity specifically associated with dual tasking was found in the left or bilateral frontal cortices. Enhanced activation in parietal areas, however, appeared not to be specifically associated with dual tasking per se, but rather with intermodal attention switching. We also expected effects of dual tasking in left frontal supramodal phonological processing areas when both component tasks required phonological processing and in right parietal supramodal spatial processing areas when both tasks required spatial processing. However, no such effects were found during these dual tasks compared with their component tasks performed separately. Taken together, the current results indicate that activations during dual tasks depend in a complex manner on specific demands of component tasks.

Top-down controlled and bottom-up triggered orienting of auditory attention to pitch activate overlapping brain networks.

A number of previous studies have suggested segregated networks of brain areas for top-down controlled and bottom-up triggered orienting of visual attention. However, the corresponding networks involved in auditory attention remain less studied. Our participants attended selectively to a tone stream with either a lower pitch or higher pitch in order to respond to infrequent changes in duration of attended tones. The participants were also required to shift their attention from one stream to the other when guided by a visual arrow cue. In addition to these top-down controlled cued attention shifts, infrequent task-irrelevant louder tones occurred in both streams to trigger attention in a bottom-up manner. Both cued shifts and louder tones were associated with enhanced activity in the superior temporal gyrus and sulcus, temporo-parietal junction, superior parietal lobule, inferior and middle frontal gyri, frontal eye field, supplementary motor area, and anterior cingulate gyrus. Thus, the present findings suggest that in the auditory modality, unlike in vision, top-down controlled and bottom-up triggered attention activate largely the same cortical networks. Comparison of the present results with our previous results from a similar experiment on spatial auditory attention suggests that fronto-parietal networks of attention to location or pitch overlap substantially. However, the auditory areas in the anterior superior temporal cortex might have a more important role in attention to the pitch than location of sounds. This article is part of a Special Issue entitled SI: Prediction and Attention.

Responsiveness and functional connectivity of the scene-sensitive retrosplenial complex in 7-11-year-old children.

Brain imaging studies have identified two cortical areas, the parahippocampal place area (PPA) and the retrosplenial complex (RSC), that respond preferentially to the viewing of scenes. Contrary to the PPA, little is known about the functional maturation and cognitive control of the RSC. Here we used functional magnetic resonance imaging and tasks that required attention to scene (or face) images and suppression of face (or scene) images, respectively, to investigate task-dependent modulation of activity in the RSC and whole-brain functional connectivity (FC) of this area in 7-11-year-old children and young adults. We compared responsiveness of the RSC with that of the PPA. The RSC was selectively activated by scene images in both groups, albeit less than the PPA. Children modulated activity between the tasks similarly in the RSC and PPA, and to the same extent as adults in PPA, whereas adults modulated activity in the RSC less than in PPA. In children, the whole brain FC of the RSC was stronger in the Sf than Fs task between the left RSC and right fusiform gyrus. The between groups comparison suggested stronger FC in children than adults in the Sf task between the right RSC and the left inferior parietal lobule and intraparietal sulcus. Together the results suggest that the function of the RSC and the related networks undergo dynamic changes over the development from 7-11-year-old children to adulthood.

HHV-6-positivity in diseases with demyelination.

BACKGROUND: The triggering agent of multiple sclerosis is still unknown and many viruses, including human herpesvirus-6 (HHV-6), are under suspicion. In earlier study we found patients who had HHV-6 reactive OCBs in their CSF. We wanted to investigate whether HHV-6 has an active role in diseases with demyelination. OBJECTIVE: To analyze the HHV-6-reactive cases in detail and investigate the possible independent role of HHV-6 in the development of central nervous system involvements with demyelination. STUDY DESIGN: We studied serum and CSF samples that were collected over a period of one year, from all patients who had oligoclonal bands (OCB) in cerebrospinal fluid (CSF) and were examined in the Department of Neurology, University Central Hospital of Helsinki, Finland. Clinical evaluation was accomplished blinded of HHV-6 analysis and follow-up time was two years. All patients underwent MRI of the head and clinically indicated CSF analysis. RESULTS: The 17 patients with HHV-6-reactive OCBs were significantly younger and had significantly more IgG-OCBs in comparison to patients without HHV-6-reactive OCBs. Initial diagnoses in patients with HHV-6-reactive OCBs remained the same during the follow-up time. CONCLUSION: Patients with HHV-6-positive OCBs appear to form a separable group. In progressive neurological diseases HHV-6 may have a role in long-term infection with demyelination.

Subtle neuropsychiatric and neurocognitive changes in hereditary gelsolin amyloidosis (AGel amyloidosis).

Hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant form of systemic amyloidosis caused by a c.640G>A or c.640G>T mutation in the gene coding for gelsolin. Principal clinical manifestations include corneal lattice dystrophy, cranial neuropathy and cutis laxa with vascular fragility. Signs of minor CNS involvement have also been observed, possibly related to cerebral amyloid angiopathy (CAA). To investigate further if AGel amyloidosis carries a risk for a specific neuropsychological or psychiatric symptomatology we studied 35 AGel patients and 29 control subjects. Neuropsychological tests showed abnormalities in visuocontructional and -spatial performance in AGel patients, also some indication of problems in processing efficacy was found. At psychiatric evaluation the patient group showed more psychiatric symptomatology, mainly depression. In brain MRI, available in 16 patients and 14 controls, we found microhemorrhages or microcalcifications only in the patient group, although the number of findings was small. Our study shows that AGel amyloidosis can be associated with visuoconstructional problems and depression, but severe neuropsychiatric involvement is not characteristic. The gelsolin mutation may even induce cerebrovascular fragility, but further epidemiological and histopathological as well as longitudinal follow-up studies are needed to clarify gelsolin-related vascular pathology and its clinical consequences.

Predictors of early mortality in young adults after intracerebral hemorrhage.

BACKGROUND AND PURPOSE: Patient and radiological characteristics of intracerebral hemorrhage (ICH), surgical treatment, and outcome after ICH are interrelated. Our purpose was to define whether these characteristics or surgical treatment correlate with mortality among young adults. METHODS: We retrospectively reviewed clinical and imaging data of all first-ever nontraumatic patients with ICH between 16 and 49 years of age treated in our hospital between January 2000 and March 2010 and linked these data with national causes of death registry. A logistic regression analysis of factors associated with 3-month mortality and a propensity score comparison between patients treated conservatively and operatively was performed. RESULTS: Among the 325 eligible patients (59.4% men), factors associated with 3-month mortality included higher National Institutes of Health Stroke Scale score, infratentorial location, hydrocephalus, herniation, and multiple hemorrhages. Adjusted for these factors, as well as demographics, ICH volume, and the underlying cause, surgical evacuation was associated with lower 3-month mortality (odds ratio, 0.06; 95% confidence interval, 0.02-0.21). In propensity score-matched analysis, 3-month case fatality rates were 3-fold in those treated conservatively (27.5% versus 7.8%; P<0.001). CONCLUSIONS: The predictors of short-term case fatality are alike in young and elderly patients with ICH. However, initial hematoma evacuation was associated with lower 3-month case fatality in our young patients with ICH.

Intravenous thrombolysis of basilar artery occlusion: thrombus length versus recanalization success.

BACKGROUND AND PURPOSE: In middle cerebral artery occlusion, probability of recanalization after intravenous tissue-type plasminogen activator thrombolysis (IVT) was reported to drop <1% for thrombi exceeding 8 mm. We aimed to evaluate the effect of thrombus length and location on success of recanalization after IVT in basilar artery occlusion. METHODS: We evaluated 164 consecutive patients with angiography-proven basilar artery occlusion and available thrombus length. We excluded 24 patients who underwent endovascular treatment. All included patients (n=140) received IVT. Thrombolysis in myocardial infarction 2 to 3 was considered as successful recanalization. RESULTS: Of the 140 included patients, 37 (26.4%) lacked post-treatment angiography, mostly because of early death. Of the remaining 103 patients, those with recanalization had shorter thrombi (median, 5.5 mm and mean, 9.7 mm) when compared with those with nonrecanalized (median, 15.0 mm and mean, 16.6 mm; P<0.001). Thrombi shorter than 10 mm had 70% to 80% probability of recanalization, whereas 10 to 20 mm, 20 to 30 mm, and >30 mm long thrombi had probabilities of 50% to 70%, 30% to 50%, and 20% to 30%, respectively. Patients with thrombi <10 mm (n=52) and recanalization had more frequently top-of-the basilar (92.5%) and less frequently caudal or midbasilar (7.5%) clot location (P=0.01). In multivariable analysis, thrombus length was independently associated with recanalization (P=0.001). Their relationship remained linear across all lengths. CONCLUSIONS: Although recanalization of basilar artery occlusion with IVT depends on thrombus length, its probability even in patients with thrombi >30 mm (20%-30%) was substantially higher than minimal recanalization of middle cerebral artery thrombi exceeding 8 mm. There was no threshold length, beyond which basilar artery occlusion recanalization with IVT could ad hoc be deemed hopeless.

Mismatch negativity abnormality in traumatic brain injury without macroscopic lesions on conventional MRI.

Traumatic brain injury (TBI) causes damage through complex pathophysiological mechanisms. Deficits related to traumatic axonal injury persist in a subset of patients with no macroscopic lesions on conventional MRI. We examined two event-related brain potentials, mismatch negativity (MMN) and P3a, to identify possible electrophysiological anomalies in this subset of TBI patients in comparison with TBI patients with focal abnormalities on MRI/computed tomography and healthy controls. Each group consisted of 10 individuals. A passive oddball paradigm, in which the individuals were instructed to ignore auditory stimuli while watching a silent movie, consisted of non-native speech sounds presented in a random order. Patients with no discernible lesions on conventional MRI showed a significantly augmented amplitude of the brain's involuntary change-detection response MMN, relative to that of the two other groups. In patients with focal neuroradiological abnormalities, this MMN anomaly was not found, whereas the subsequent orientation-related P3a response was significantly enlarged when compared with that of the controls. The present findings demonstrate that MMN is indicative of a functional abnormality in the mechanisms of involuntary attention in chronic TBI patients with normal conventional MRI findings, indexing their increased distractibility associated with the traumatically-induced loss of neural integrity.

Thrombolysis of basilar artery occlusion: impact of baseline ischemia and time.

OBJECTIVE: To evaluate the impact of extensive baseline ischemic changes on functional outcome after thrombolysis of basilar artery occlusion (BAO), and to study the effect of time to treatment in the absence of such findings. METHODS: We prospectively evaluated 184 consecutive patients with angiography-proven BAO. The majority of patients received intravenous alteplase and concomitant full-dose heparin. Extensive baseline ischemia was defined as posterior circulation Acute Stroke Prognosis Early CT score (pc-ASPECTS) < 8. Onset-to-treatment time (OTT) was evaluated both as a continuous and as a categorical variable (0-6 hours, 6-12 hours, 12-24 hours, and 24-48 hours). Successful recanalization means thrombolysis in myocardial infarction (TIMI) = 2 to 3. Symptomatic intracranial hemorrhage (sICH) was evaluated with National Institute of Neurological Disorders and Stroke, European Cooperative Acute Stroke Study II, and Safe Implementation of Thrombolysis in Stroke criteria. Poor 3-month outcome was defined as modified Rankin Scale score of 3 to 6. RESULTS: The majority (96%) of patients with baseline pc-ASPECTS < 8 had poor 3-month outcome, and a similar number (94%) was observed in those of them with confirmed recanalization (51.5%). In contrast, half of the patients with pc-ASPECTS ≥ 8 and successful recanalization (73.2%) achieved good outcome. In these patients, OTT was associated with poor outcome neither as a continuous nor as a categorical variable. Factors independently associated with poor outcome were greater age and baseline National Institutes of Health Stroke Scale, lack of recanalization, history of atrial fibrillation, and sICH. In the model including the whole cohort (patients with any pc-ASPECTS), pc-ASPECTS < 8 was independently associated with poor outcome (odds ratio = 5.83, 95% confidence interval = 1.09-31.07). INTERPRETATION: In the absence of extensive baseline ischemia, recanalization of BAO up to 48 hours was seldom futile and produced good outcomes in 50% of patients, which was independent of time to treatment.

D-dimer and clinicoradiologic features in cerebral venous thrombosis.

OBJECTIVES: Cerebral venous thrombosis (CVT) is a disease with varying clinical presentation and diagnosis presents many challenges in clinical practice. We investigated, whether D-dimer levels reflect clinical presentation, radiologic features, and outcome in CVT. METHODS: We included all consecutive patients with CVT treated in our hospital from 1987 to 2010 with D-dimer levels measured before initiation of anticoagulant treatment. D-dimer was categorized as low (<0.5mg/L), intermediate (0.6-2.0mg/L), and high (>2.0mg/L). Based on delay from symptom onset to hospital presentation mode of onset was categorized as acute (<2 days), subacute (2-14 days), or chronic (>14 days). RESULTS: In 71 patients included median level of D-dimer was 1.40 mg/L (range 0.05-13.0mg/L). In 9 (12%) patients D-dimer was low, and of these, 7 presented with subacute and 2 with chronic mode of symptom duration. Elevated D-dimer levels were associated with thrombosis in multiple sinuses (P=0.044). Longer symptom duration was correlated with low D-dimer levels (P=0.010). CONCLUSIONS: In clinical practice, low levels of D-dimer cannot rule out CVT in patients with subacute or chronic disease. High D-dimer levels correlate with greater thrombus extension and acute onset of symptoms.

Task-dependent activations of human auditory cortex to prototypical and nonprototypical vowels.

Research in auditory neuroscience has largely neglected the possible effects of different listening tasks on activations of auditory cortex (AC). In the present study, we used high-resolution fMRI to compare human AC activations with sounds presented during three auditory and one visual task. In all tasks, subjects were presented with pairs of Finnish vowels, noise bursts with pitch and Gabor patches. In the vowel pairs, one vowel was always either a prototypical /i/ or /ae/ (separately defined for each subject) or a nonprototype. In different task blocks, subjects were either required to discriminate (same/different) vowel pairs, to rate vowel "goodness" (first/second sound was a better exemplar of the vowel class), to discriminate pitch changes in the noise bursts, or to discriminate Gabor orientation changes. We obtained distinctly different AC activation patterns to identical sounds presented during the four task conditions. In particular, direct comparisons between the vowel tasks revealed stronger activations during vowel discrimination in the anterior and posterior superior temporal gyrus (STG), while the vowel rating task was associated with increased activations in the inferior parietal lobule (IPL). We also found that AC areas in or near Heschl's gyrus (HG) were sensitive to the speech-specific difference between a vowel prototype and nonprototype during active listening tasks. These results show that AC activations to speech sounds are strongly dependent on the listening tasks.

Brain activity during auditory and visual phonological, spatial and simple discrimination tasks.

We used functional magnetic resonance imaging to measure human brain activity during tasks demanding selective attention to auditory or visual stimuli delivered in concurrent streams. Auditory stimuli were syllables spoken by different voices and occurring in central or peripheral space. Visual stimuli were centrally or more peripherally presented letters in darker or lighter fonts. The participants performed a phonological, spatial or "simple" (speaker-gender or font-shade) discrimination task in either modality. Within each modality, we expected a clear distinction between brain activations related to nonspatial and spatial processing, as reported in previous studies. However, within each modality, different tasks activated largely overlapping areas in modality-specific (auditory and visual) cortices, as well as in the parietal and frontal brain regions. These overlaps may be due to effects of attention common for all three tasks within each modality or interaction of processing task-relevant features and varying task-irrelevant features in the attended-modality stimuli. Nevertheless, brain activations caused by auditory and visual phonological tasks overlapped in the left mid-lateral prefrontal cortex, while those caused by the auditory and visual spatial tasks overlapped in the inferior parietal cortex. These overlapping activations reveal areas of multimodal phonological and spatial processing. There was also some evidence for intermodal attention-related interaction. Most importantly, activity in the superior temporal sulcus elicited by unattended speech sounds was attenuated during the visual phonological task in comparison with the other visual tasks. This effect might be related to suppression of processing irrelevant speech presumably distracting the phonological task involving the letters.

Regulation of brain activity in the fusiform face and parahippocampal place areas in 7-11-year-old children.

Developmental studies have demonstrated that cognitive processes such as attention, suppression of interference and memory develop throughout childhood and adolescence. However, little is currently known about the development of top-down control mechanisms and their influence on cognitive performance. In the present study, we used functional magnetic resonance imaging to investigate modulation of activity in the ventral visual cortex in healthy 7-11-year-old children and young adults. The participants performed tasks that required attention to either face (Fs task) or scene (Sf task) images while trying to ignore distracting scene or face images, respectively. A face-selective area in the fusiform gyrus (fusiform face area, FFA) and an area responding preferentially to scene images in the parahippocampal gyrus (parahippocampal place area, PPA) were defined using functional localizers. Children responded slower and less accurately in the tasks than adults. In children, the right FFA was less selective to face images and regulation of activity between the Fs and Sf tasks was weaker compared to adults. In the PPA, selectivity to scenes and regulation of activity, there according to the task demands were comparable between children and adults. During the tasks, children activated prefrontal cortical areas including the middle (MFG) and superior (SFG) frontal gyrus more than adults. Functional connectivity between the right FFA and left MFG was stronger in adults than children in the Fs task. Children, on the other hand, had stronger functional connectivity than adults in the Sf task between the right FFA and right PPA and between right MFG and medial SFG. There were no group differences in the functional connectivity between the PPA and the prefrontal cortex (PFC). Together the results suggest that, in 7-11-year-old children, the FFA is still immature, whereas the selectivity to scenes and regulation of activity in the PPA is comparable to adults. The results also indicated functional immaturity of the PFC in children compared to adults and weaker connectivity between the PFC and the rFFA, explaining the weaker regulation of activity in the rFFA between the Fs and Sf tasks.