Attention network impairments in patients with focal frontal or parietal lesions

Unveiling altered connectivity between cognitive networks and cerebellum in schizophrenia

Cognitive functioning is a crucial aspect in schizophrenia (SZ), and when altered it has devastating effects on patients' quality of life and treatment outcomes. Several studies suggested that they could result from altered communication between the cortex and cerebellum. However, the neural correlates underlying these impairments have not been identified. In this study, we investigated resting state functional connectivity (rsFC) in SZ patients, by considering the interactions between cortical networks supporting cognition and cerebellum. In addition, we investigated the relationship between SZ patients' rsFC and their symptoms. We used fMRI data from 74 SZ patients and 74 matched healthy controls (HC) downloaded from the publicly available database SchizConnect. We implemented a seed-based connectivity approach to identify altered functional connections between specific cortical networks and cerebellum. We considered ten commonly studied resting state networks, whose functioning encompasses specific cognitive functions, and the cerebellum, whose involvement in supporting cognition has been recently identified. We then explored the relationship between altered rsFC values and Positive and Negative Syndrome Scale (PANSS) scores. The SZ group showed increased connectivity values compared with HC group for cortical networks involved in attentive processes, which were also linked to PANSS items describing attention and language-related processing. We also showed decreased connectivity between cerebellar regions, and increased connectivity between them and attentive networks, suggesting the contribution of cerebellum to attentive and affective deficits. In conclusion, our findings highlighted the link between negative symptoms in SZ and altered connectivity within the cerebellum and between the same and cortical networks supporting cognition.

Metamemory and executive function mediate the age-related decline in memory

OBJECTIVE

Although the effect of aging on episodic memory is relatively well studied, little is known about how aging influences metamemory. In addition, while executive function (EF) is known to mediate the age-related decline in episodic memory, the role of metamemory in aging-related memory differences beyond EF remains unknown. This study aimed to elucidate the effect of aging on metamemory and to clarify the role of metamemory in the age-related decline in memory.

METHOD

One hundred and four adults aged 18-79 years (50 M, 54 F) performed several EF tasks, as well as a face-scene paired-associate learning task that required them to make judgments of learning, feeling-of-knowing judgments, and retrospective confidence judgments.

RESULTS

Aging was significantly associated with poor metamemory accuracy and increased confidence across metamemory judgment types, even after controlling for EF and memory performance. A parallel mediation analysis indicated that both confidence of learning and EF performance had significant partial mediation effects on the relationship between aging and memory, albeit in different ways. Specifically, poor EF explained the age-related decline in memory, whereas increased confidence of learning served to compensate for this memory decline.

CONCLUSIONS

Aging is associated with general changes (i.e., poor inferences from cues) rather than specific changes (i.e., declined activation or utilization of certain cues) in metamemory monitoring. Also, changes in confidence of learning and in EF ability contribute to the preservation and decline of memory during aging, respectively. Therefore, boosting confidence during encoding and enhancing EF skills might be complementary memory intervention strategies for older adults.

Comparisons of electrophysiological markers of impaired executive attention after traumatic brain injury and in healthy aging

Executive attention impairments are a persistent and debilitating consequence of traumatic brain injury (TBI). To make headway towards treating and predicting outcomes following heterogeneous TBI, cognitive impairment specific pathophysiology first needs to be characterized. In a prospective observational study, we measured EEG during the attention network test aimed at detecting alerting, orienting, executive attention and processing speed. The sample (N = 110) of subjects aged 18-86 included those with and without traumatic brain injury: n = 27, complicated mild TBI; n = 5, moderate TBI; n = 10, severe TBI; n = 63, non-brain-injured controls. Subjects with TBI had impairments in processing speed and executive attention. Electrophysiological markers of executive attention processing in the midline frontal regions reveal that, as a group, those with TBI and elderly non-brain-injured controls have reduced responses. We also note that those with TBI and elderly controls have responses that are similar for both low and high-demand trials. In subjects with moderate-severe TBI, reductions in frontal cortical activation and performance profiles are both similar to that of controls who are ∼4 to 7 years older. Our specific observations of frontal response reductions in subjects with TBI and in older adults is consistent with the suggested role of the anterior forebrain mesocircuit as underlying cognitive impairments. Our results provide novel correlative data linking specific pathophysiological mechanisms underlying domain-specific cognitive deficits following TBI and with normal aging. Collectively, our findings provide biomarkers that may serve to track therapeutic interventions and guide development of targeted therapeutics following brain injuries.

Context-specific effects of threatening faces on alerting, orienting, and executive control: A fNIRS study

Real-world threatening faces possess both useful and irrelevant attributes with respect to the current goal. How these attributes interact and affect attention, which comprises at least three processes hypothesized to engage the frontal lobes (alerting, orienting, and executive control), remains poorly understood. Here, the neurocognitive effects of threatening facial expressions on the three processes of attention were examined through the emotional Attention Network Test (ANT) and functional near-infrared spectroscopy (fNIRS). Forty-seven (20M, 27F) young adults performed a blocked version of the arrow flanker task with neutral and angry facial cues applied in three cue conditions (no, center, and spatial). Hemodynamic changes occurring in participants' frontal cortices during task performance were recorded by multichannel fNIRS. Behavioral results indicated that alerting, orienting, and executive control processes existed in both the neutral and angry conditions. However, depending on the context, angry facial cues affected these processes differently compared with neutral facial cues. Specifically, the angry face disrupted the classical decrease in reaction time from the no-cue to center-cue condition specifically during the congruent condition. Additionally, fNIRS results revealed significant frontal cortical activation during the incongruent vs. congruent task; neither cue nor emotion significantly affected frontal activation. Thus, the findings suggest that the angry face affects all three attentional processes while exerting context-specific effects on attention. They also imply that during the ANT, the frontal cortex is most involved in executive control. The present study offers essential insights into how various attributes of threatening faces interact and alter attention.

The study of functional connectivity of attention cognitive impairment in children with nocturnal enuresis

We aimed to explore the brain functional connectivity mechanism of attention cognitive impairment in children with nocturnal enuresis (NE). Children with NE often show attention cognitive deficit, but its brain mechanism remains unclear. Most previous studies have only focused on a single brain region, without involving the association among brain regions. In this study, 26 NE and 26 normal children were selected. Functional magnetic resonance imaging (fMRI) and integrated visual and auditory continuous performance test (IVA-CPT) were performed. The 12 key brain regions of the dorsal attention network (DAN), default mode network (DMN), and ventral attention network (VAN) were selected as areas of interest, and 66 groups of functional connectivity (FC) were analyzed among these 12 brain regions. The correlation between FC and IVA-CPT in the two groups was analyzed. The FC values showed that the groups with significant differences between NE and normal children were lFEF-aMPFC, rFEF-lIFG, rFEF-rIPS, and lAG-VFC (P<0.05), and the FC value of lAG-VFC was positively correlated with the Full-Scale Attention Quotient (FAQ). Our results showed that attention deficit in children with NE was associated with all three networks and was relative to the FC among the three attention networks. DAN was the brain network most related to attention cognition in children with NE, and most of the brain regions with abnormal connectivity in NE were related to the prefrontal lobe. The lAG was also an important brain region in attention impairment in NE.

Longitudinal alterations in gamma-aminobutyric acid (GABAA) receptor availability over ∼ 1 year following traumatic brain injury

Longitudinal alterations of gamma-aminobutyric acid (GABA_A) receptor availability following traumatic brain injury have remained uncharacterized and may reflect changes in neuronal structure and function linked to cognitive recovery. We measured GABA_A receptor availability using the tracer [11C]flumazenil in nine adults with traumatic brain injury (3–6 months after injury, subacute scan) and in 20 non-brain-injured individuals. A subset of subjects with traumatic brain injury (n = 7) were scanned at a second chronic time-point, 7–13 months after their first scan; controls (n = 9) were scanned for a second time, 5–11 months after the first scan. After accounting for atrophy in subjects with traumatic brain injury, we find broad decreases in GABA_A receptor availability predominantly within the frontal lobes, striatum, and posterior-medial thalami; focal reductions were most pronounced in the right insula and anterior cingulate cortex (p < 0.05). Greater relative increase, compared to controls, in global GABA_A receptor availability appeared between subacute and chronic scans. At chronic scan (>1 year post-injury), we find increased pallidal receptor availability compared to controls. Conversely, receptor availability remained depressed across the frontal cortices. Longitudinal improvement in executive attention correlated with increases in receptor availability across bilateral fronto-parietal cortical regions and the anterior-lateral aspects of the thalami. The specific observations of persistent bi-frontal lobe reductions and bilateral pallidal elevation are consistent with the anterior forebrain mesocircuit hypothesis for recovery of consciousness following a wide range of brain injuries; our results provide novel correlative data in support of specific cellular mechanisms underlying persistent cognitive deficits. Collectively, these measurements support the use of [11C]flumazenil to track recovery of large-scale network function following brain injuries and measure response to therapeutics.

Individual Optimal Attentional Strategy in Motor Learning Tasks Characterized by Steady-State Somatosensory and Visual Evoked Potentials

Focus of attention is one of the most influential factors facilitating motor performance. Previous evidence supports that the external focus (EF) strategy, which directs attention to movement outcomes, is associated with better motor performance than the internal focus (IF) strategy, which directs attention to body movements. However, recent studies have reported that the EF strategy is not effective for some individuals. Furthermore, neuroimaging studies have demonstrated that the frontal and parietal areas characterize individual optimal attentional strategies for motor tasks. However, whether the sensory cortices are also functionally related to individual optimal attentional strategy remains unclear. Therefore, the present study examined whether an individual’s sensory processing ability would reflect the optimal attentional strategy. To address this point, we explored the relationship between responses in the early sensory cortex and individuals’ optimal attentional strategy by recording steady-state somatosensory evoked potentials (SSSEP) and steady-state visual evoked potentials (SSVEP). Twenty-six healthy young participants first performed a motor learning task with reaching movements under IF and EF conditions. Of the total sample, 12 individuals showed higher after-effects under the IF condition than the EF condition (IF-dominant group), whereas the remaining individuals showed the opposite trend (EF-dominant group). Subsequently, we measured SSSEP from bilateral primary somatosensory cortices while presenting vibrotactile stimuli and measured SSVEP from bilateral primary visual cortices while presenting checkerboard visual stimuli. The degree of increasing SSSEP response when the individuals in the IF-dominant group directed attention to vibrotactile stimuli was significantly more potent than those in the EF-dominant individuals. By contrast, the individuals in the EF-dominant group showed a significantly larger SSVEP increase while they directed attention to visual stimuli compared with the IF-dominant individuals. Furthermore, a significant correlation was observed such that individuals with more robust IF dominance showed more pronounced SSSEP attention modulation. These results suggest that the early sensory areas have crucial brain dynamics to characterize an individual’s optimal attentional strategy during motor tasks. The response characteristics may reflect the individual sensory processing ability, such as control of priority to the sensory inputs. Considering individual cognitive traits based on the suitable attentional strategy could enhance adaptability in motor tasks.

Attention Bias to Pain Words Comes Early and Cognitive Load Matters: Evidence from an ERP Study on Experimental Pain

Attention bias (AB) is a common cognitive challenge for patients with pain. In this study, we tested at what stage AB to pain occurs in participants with experimental pain (EP) and tested whether cognitive load interferes with it. We recruited 40 healthy adults aged 18-27 years, and randomized them into control and EP groups. We sprayed the participants in the EP group with 10% capsaicin paste to mimic acute pain and those in the control group with water, accessing both groups' behavioral results and event-related potential data. We found that high-load tasks had longer response times and lower accuracies than low-load tasks did and that different neural processing of words occurred between the groups. The EP group exhibited AB to pain at an early stage with both attentional avoidance (N1 latency) and facilitated attention (P2 amplitude) to pain words. The control group coped with semantic differentiation (N1) at first, followed by pain word discrimination (P2). In addition, AB to pain occurred only in low-load tasks. As the cognitive load multiplied, we did not find AB in the EP group. Therefore, our study adds further evidence for AB to pain, suggesting the implementation of cognitive load in future AB therapy.

Dissociated deficits in attentional networks in social anxiety and depression

A critical cognitive symptom that is commonly involved in social anxiety and depression is attentional deficit. However, the functional relationship between attentional deficit and these two disorders remains poorly understood. Here, we behaviorally disentangled the three key attentional components (alerting, orienting, and executive control) using the established attentional network task (ANT) to investigate how social anxiety and depression are related to deficits in these attention components. We identified a double dissociation between the symptoms of social anxiety and depression and the attentional component deficits when processing non-emotional stimuli. While individuals vulnerable to social anxiety exhibited deficits in the orienting component, individuals vulnerable to depression were impaired in the executive control component. Our findings showed that social anxiety and depression were associated with deficits in different attentional components, which are not specific to emotional information.

Laterality of Attentional Networks in Patients With Cerebral Small Vessel Disease

Introduction: Problems with attention are common in patients with cerebral small vessel disease (CSVD). The normal human brain exhibits functional and structural asymmetry. However, it is unknown whether there is lateralization of attention in patients with CSVD.

Objective: This study aims to investigate attention separately in both cerebral hemispheres in patients with CSVD using the computer-based Lateralized Attention Network Test—Revised (LANT-R).

Methods: The total number of subjects included was 58, which includes the CSVD (N = 35) and healthy control (HC, N = 23) groups. All subjects completed the LANT-R paradigm and neuropsychological background tests.

Results: The results indicate that there is an left hemisphere (LH) lateralization in orienting network efficiency in the HC group. However, this lateralization was not apparent in the CSVD group. Furthermore, the difference between groups was significant (interaction P = 0.02). In addition, the scores of subjects in the CSVD group are lower in several cognitive domains, including attention function, memory function, information processing speed, and executive function, compared with the controls.

Conclusion: Patients with CSVD change in the lateralization of attention compared with the normal elderly. The decrease in attention in patients with CSVD might be caused by the reduced ability of selecting useful information in the LH.

Differences of attentional networks function in athletes from open-skill sports: an functional near-infrared spectroscopy study

OBJECTIVE

The purpose of this study was to investigate the attentional networks function characteristics of interceptive and strategic sports athletes from open-skill sports.

METHODS

We used a revised lateralized attention network task to measure attentional networks efficiency and activation related to flanker conflict effects, alerting effects, and orienting effects changes on the right frontoparietal network using functional near-infrared spectroscopy in 20 strategic sports athletes, 20 interceptive sports athletes, and 22 college students.

RESULTS

The interceptive sports athletes had the fastest overall reaction time. Strategic sports athletes had the highest accuracy and smallest flanker conflict effect on accuracy. Compared with non-athletes, strategic sports athletes had a higher alerting effect, validity effect, and disengaging effect on reaction time; the disengaging effect was particularly higher than that in the interceptive sports athletes. This was accompanied by higher activity in the right frontoparietal network.

CONCLUSIONS

The open-skill athletes demonstrate significantly more efficient attentional function compared to non-athletes. Athletes from interceptive sports demonstrated increased speed when solving conflict, while those from strategic sports demonstrated higher accuracy. In addition, top-down control appears to play an important role in strategic sports athletes making a cautious decision. This can be attributed to the right frontoparietal network.

Resting-state brain entropy in right temporal lobe epilepsy and its relationship with alertness

BACKGROUND

To date, no functional MRI (fMRI) studies have focused on brain entropy in right temporal lobe epilepsy (rTLE) patients. Here, we characterized brain entropy (BEN) alterations in patients with rTLE using resting-state functional MRI(rs-fMRI) and explored the relationship between BEN and alertness.

METHOD

Thirty-one rTLE patients and 33 controls underwent MRI scanning to investigate differences in BEN and resting-state functional connectivity (rs-FC) in regions of interest (ROIs) between patients and controls. Correlation analyses were performed to examine relationships between the BEN of each ROI and alertness reaction times (RTs) in rTLE patients.

RESULTS

Compared with controls, the BEN of rTLE patients was significantly increased in the right middle temporal gyrus, inferior temporal gyrus, and other regions of the left hemisphere and significantly decreased in the right middle frontal gyrus and left supplementary motor area (p < .05). The rs-FCs between the ROIs (at p < .01, with the left superior parietal lobule and right precentral gyrus defined as ROI1 and ROI2, respectively) and the whole brain showed an increasing trend in rTLE patients. In addition, the BEN of ROI2 was associated with the intrinsic alertness and phasic alertness RTs of patients with rTLE.

CONCLUSIONS

Our findings suggest that BEN is altered in patients with rTLE and that decreased BEN in the right precentral gyrus is positively related to intrinsic and phasic alertness; the abnormal FC in the brain regions with altered entropy suggests a reconstruction of brain functional connectivity. These findings suggest that BEN mapping may provide a useful tool for probing brain mechanisms related to TLE.

Individual optimal attentional strategy during implicit motor learning boosts frontoparietal neural processing efficiency: A functional near-infrared spectroscopy study

INTRODUCTION

Optimal focus of attention is a crucial factor for improving motor learning. Most previous studies have shown that directing attention to movement outcome (external focus; EF) is more effective than directing attention to body movement itself (internal focus; IF). However, our recent studies demonstrated that the optimal attentional strategy in healthy and clinical populations varies depending on individual motor imagery ability. To explore the neurological basis underlying individual optimal attentional strategy during motor learning tasks, in the present study, we measured frontoparietal activities using functional near-infrared spectroscopy (fNIRS).

METHODS

Twenty-eight participants performed a visuomotor learning task requiring circular tracking. During the task, the participants were required to direct their attention internally or externally. The individual optimal attentional strategy was determined by comparing the after-effect sizes between the IF and EF conditions.

RESULTS

Fifteen participants showed larger after-effects under the EF condition (External-dominant), whereas the others showed larger after-effects under the IF condition (Internal-dominant). Based on the differences in neural activities between Internal- and External-dominant groups, we identified the right dorsolateral prefrontal cortex (Brodmann area 46) and right somatosensory association cortex (Brodmann area 7) as the neural bases associated with individual optimal attentional strategy during motor learning. Furthermore, we observed a significant negative correlation, that is, lower activity in these areas was associated with a larger after-effect size under the optimal attentional strategy.

CONCLUSION

Our findings demonstrated that more efficient neural processing in the frontoparietal area under the individual optimal attentional strategy can accelerate motor learning.

Infant fMRI: A Model System for Cognitive Neuroscience

Our understanding of the typical human brain has benefitted greatly from studying different kinds of brains and their associated behavioral repertoires, including animal models and neuropsychological patients. This same comparative perspective can be applied to early development - the environment, behavior, and brains of infants provide a model system for understanding how the mature brain works. This approach requires noninvasive methods for measuring brain function in awake, behaving infants. fMRI is becoming increasingly viable for this purpose, with the unique ability to precisely measure the entire brain, including both cortical and subcortical structures. Here we discuss potential lessons from infant fMRI for several domains of adult cognition and consider the challenges of conducting such research and how they might be mitigated.

Executive attention deficits after traumatic brain injury reflect impaired recruitment of resources

Deficits in attention are a common and devastating consequence of traumatic brain injury (TBI), leading to functional impairments, rehabilitation barriers, and long-term disability. While such deficits are well documented, little is known about their underlying pathophysiology hindering development of effective and targeted interventions. Here we evaluate the integrity of brain systems specific to attentional functions using quantitative assessments of electroencephalography recorded during performance of the Attention Network Test (ANT), a behavioral paradigm that separates alerting, orienting, and executive components of attention. We studied 13 patients, at least 6 months post-TBI with cognitive impairments, and 24 control subjects. Based on performance on the ANT, TBI subjects showed selective impairment in executive attention. In TBI subjects, principal component analysis combined with spectral analysis of the EEG after target appearance extracted a pattern of increased frontal midline theta power (2.5–7.5 Hz) and suppression of frontal beta power (12.5–22.5 Hz). Individual expression of this pattern correlated (r = − 0.67, p < 0.001) with executive attention impairment. The grading of this pattern of spatiotemporal dynamics with executive attention deficits reflects impaired recruitment of anterior forebrain resources following TBI; specifically, deafferentation and variable disfacilitation of medial frontal neuronal populations is proposed as the basis of our findings.

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Electrophysiological correlate of impaired executive attention after Traumatic Brain Injury is derived.

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Theta increases in medial frontal and beta suppression in frontal regions is linked to behavioral performance.

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Individual-specific pathophysiology allows for tracking of recovery/interventions and studies of function-structure.

Impairment of the executive attention network in premenopausal women with hormone receptor-positive breast cancer treated with tamoxifen

Tamoxifen (TAM) is most commonly prescribed for patients with hormone-sensitive breast cancer and exerts agonistic/antagonistic effects on estrogen receptors throughout the body. Accumulating evidence has revealed that breast cancer patients receiving TAM manifest cognitive dysfunction. However, whether these patients have a global attention deficit or a more selective impairment of specific attention networks remains unknown. In the present study, we sought to explore the attention function of premenopausal women with hormone receptor-positive breast cancer treated with TAM using the attention network test (ANT). The subjects included breast cancer patients receiving TAM (TAM, N=43), breast cancer patients not receiving TAM (non-TAM, N=41), and matched healthy controls (HC, N=46). The subjects completed the ANT and neuropsychological tests, which measure three independent attention networks and executive function performance, respectively. Our results indicated that patients in the TAM group had significant deficits in their executive control component but not in the alerting or orienting components. Moreover, the patients showed poor executive function performance in the neuropsychological tests. Additionally, in the TAM group, significant correlations were found between the decreased efficiency of the executive control component and their reduced performance in executive function tests. This study demonstrates that premenopausal women with hormone receptor-positive breast cancer treated with TAM have impairment of the executive attention network and that this impairment was associated with differences in executive function performance.

Selective impairment of attention networks during propofol anesthesia after gynecological surgery in middle-aged women

BACKGROUND

Postoperative cognitive dysfunction is a common complication of anesthesia and surgery. Attention networks are essential components of cognitive function and are subject to impairment after anesthesia and surgery. It is not known whether such impairment represents a global attention deficit or relates to a specific attention network. We used an Attention Network Task (ANT) to examine the efficiency of the alerting, orienting, and executive control attention networks in middle-aged women (40-60 years) undergoing gynecologic surgery. A matched group of medical inpatients were recruited as a control.

METHODS

Fifty female patients undergoing gynecologic surgery (observation group) and 50 female medical inpatients (control group) participated in this study. Preoperatively patients were administered a mini-mental state examination as a screening method. The preoperative efficiencies of three attention networks in an attention network test were compared to the 1st and 5th post-operative days.

RESULTS

The control group did not have any significant attention network impairments. On the 1st postoperative day, significant impairment was shown in the alerting (p=0.003 vs. control group, p=0.015 vs. baseline), orienting (p<0.001 vs. both baseline level and control group), and executive control networks (p=0.007 vs. control group, p=0.002 vs. baseline) of the observation group. By the 5th postoperative day, the alerting network efficiency had recovered to preoperative levels (p=0.464 vs. baseline) and the orienting network efficiency had recovered partially (p=0.031 vs. 1st post-operative day), but not to preoperative levels (p=0.01 vs. baseline). The executive control network did not recover by the 5th postoperative day (p=0.001 vs. baseline, p=0.680 vs. 1st post-operative day).

CONCLUSIONS

Attention networks of middle-aged women show a varying degree of significant impairment and differing levels of recovery after surgery and propofol anesthetic.

Attention dysfunction of postoperative patients with glioma

Background

Attention dysfunction has been observed among many kinds of nervous system diseases, including glioma. This study aimed to investigate the correlation between glioma localization, malignancy, postoperative recovery time and attention deficit.

Methods

A total of 45 patients with glioma who underwent surgical resection and 18 healthy volunteers were enrolled. The attention network test, digital span test, color trail test II and Stroop test were used to detect the characteristics of attention deficit.

Results

Orientation network dysfunction was detected in the parietal lobe tumor group, and execution network deficit was detected in both the frontal and parietal lobe groups, while no significant difference was detected in the temporal lobe group compared to healthy controls. The high-grade glioma group (grade III-IV) exhibited more serious functional impairment than the low-grade group (grade I-II). No significant correlation was observed between postoperative recovery time and attention impairment.

Conclusions

High-grade glioma patients suffer more severe attention impairment. In addition, the frontal and parietal lobe glioma patients suffer attention dysfunction in dissimilar manner. These findings will provide important guidance on the care of glioma patients after therapy.

Selective impairment of attention networks in breast cancer patients receiving chemotherapy treatment

INTRODUCTION

Complaints about attention disorders are common among breast cancer survivors who have undergone chemotherapy treatment. However, it is not known whether these complaints indicate a global attention deficit or the selective impairment of attention networks.

OBJECTIVE

This study sought to investigate the attentional abilities of breast cancer patients after chemotherapy treatment using the attention network test (ANT).

METHODS

The participants included breast cancer patients who had undergone chemotherapy (CT, N = 58), patients who had not undergone chemotherapy (non-CT, N = 53), and matched healthy controls (HC, N = 55). All participants completed the ANT, which provides measures of three independent attention networks (alerting, orienting, and executive control) and neuropsychological background tests.

RESULTS

Our results indicated that the chemotherapy-treated breast cancer patients had significant deficits in the alerting and executive control networks but not in the orienting network. The CT group scored significantly lower in several cognitive tasks, including attention, memory, and information processing tasks, relative to the other two groups. Additionally, significant correlations were found between information processing and the efficiency of the executive control network within the CT group.

CONCLUSIONS

These results suggest that the three attention networks were selectively impaired following chemotherapy treatment, which affected different brain areas in the breast cancer survivors.

Traumatic injury to the immature frontal lobe: a new murine model of long-term motor impairment in the absence of psychosocial or cognitive deficits

Traumatic brain injury in children commonly involves the frontal lobes and is associated with distinct structural and behavioral changes. Despite the clinical significance of injuries localized to this region during brain development, the mechanisms underlying secondary damage and long-term recovery are poorly understood. Here, we have characterized the first model of unilateral focal traumatic injury to the developing frontal lobe. Male C57Bl/6J mice at postnatal day (p)21, an age approximating a toddler-aged child, received a controlled cortical impact or sham surgery to the left frontal lobe and were euthanized 1 or 7 days later. A necrotic cavity and local inflammatory response were largely confined to the unilateral frontal lobe, dorsal corpus callosum and striatum anterior to the bregma. While cell death and accumulated β-amyloid precursor protein were characteristic features of the pericontusional motor cortex, corpus callosum, cingulum and dorsal striatum, underlying structures including the hippocampus showed no overt pathology. To determine the long-term functional consequences of injury at p21, two additional cohorts were subjected to a battery of behavioral tests in adolescence (p35-45) or adulthood (p70-80). In both cohorts, brain-injured mice showed normal levels of anxiety, sociability, spatial learning and memory. The signature phenotypic features were deficits in motor function and motor learning, coincident with a reduction in ipsilateral cortical brain volumes. Together, these findings demonstrate classic morphological features of a focal traumatic injury, including early cell death and axonal injury, and long-term volumetric loss of cortical volumes. The presence of deficits in sensorimotor function and coordination in the absence of abnormal findings related to anxiety, sociability and memory likely reflects several variables, including the unique location of the injury and the emergence of favorable compensatory mechanisms during subsequent brain development.