Cognitive disconnective syndrome by single strategic strokes in vascular dementia

Simultaneous Four Supratentorial Lesions Predict Tube Dependency Due to an Impaired Anticipatory Phase of Ingestion

This study aimed to identify the neuroanatomical predictors of oropharyngeal dysphagia and tube dependency in patients with supratentorial or infratentorial ischemic strokes. Patients with acute ischemic stroke were enrolled and were classified into 3 groups: right supratentorial (n = 61), left supratentorial (n = 89), and infratentorial stroke (n = 50). Dysphagia was evaluated by a modified water swallowing test and the Food Intake LEVEL Scale to evaluate oropharyngeal dysphagia and tube dependency, respectively. As two dysphagia parameters, we evaluated the durations from onset of stroke to (1) success in the modified water swallowing test and to (2) rating 7 points or above on the Food Intake LEVEL Scale: patients regained sufficient oral intake and were not tube-dependent. Voxel-based lesion-symptom mapping analysis was performed for a spatially normalized lesion map of magnetic resonance imaging to explore the anatomies that are associated with the two dysphagia parameters for each stroke group. The right precentral gyrus and parts of the internal capsule are associated with oropharyngeal dysphagia. The four supratentorial areas are associated with tube dependency. The dorsal upper medulla is associated with both oropharyngeal dysphagia and tube dependency. These results suggest that supratentorial stroke patients can be tube-dependent due to an impaired anticipatory phase of ingestion. The simultaneous damage in the four supratentorial areas: the inferior part of the precentral gyrus, lenticular nucleus, caudate head, and anterior insular cortex, predicts tube dependency. In contrast, infratentorial stroke patients can be tube-dependent due to oropharyngeal dysphagia caused by lesions in the dorsal upper medulla, damaging the swallowing-related nucleus.

Role of neurorehabilitation in the recovery of bilateral thalamic stroke related to the artery of Percheron anatomical variant

Bilateral thalamic stroke is a rare condition, mostly related to the presence of the artery of Percheron (AoP) variant. The clinical presentation of AoP-related strokes is remarkably heterogeneous and often includes cognitive and behavioural alterations. Our report describes the clinical course of an AoP-related bilateral thalamic stroke and highlights the pivotal role of a tailored rehabilitation programme plays in enhancing recovery. A man in his 40s was admitted to the neurology ward due to the abrupt onset of mental status alterations and weakness in his left limbs. The first brain CT scan and subsequent MRI exam revealed a bilateral thalamic stroke and the presence of an AoP anatomical variant. After the first critical phase, the patient's condition became stable, but he still suffered from severe attention, memory and speech deficits. The patient was then transferred to the rehabilitation unit and was subjected to a tailored neurorehabilitation programme that allowed a complete recovery of the symptoms. Neurorehabilitation plays a pivotal role in the patient's recovery and should always be pursued to minimise the residual deficits and, most importantly, to prevent permanent cognitive deficits.

Cognitive Impairment in Strategic Infarct Dementia: A Report of Three Cases

Strokes involving specific areas regulating cognition and behavioral functions constitute strategic infarct vascular dementia. We present three patients with acute behavioral changes and cognitive impairment following a strategic infarct. Case 1 is of a 59-year-old male, a known patient of diabetes mellitus under treatment, who presented with acute onset of memory deficit along with difficulty in recognizing faces, and left hemispatial neglect. Case 2 is of a 62-year-old male, a smoker, who presented with acute onset of behavioral abnormalities, gait apraxia, and decreased word output. Case 3 is of a 64-year-old female, a known patient of type 2 diabetes mellitus and cerebrovascular accident with left hemiparesis, who presented with psychomotor withdrawal, depression, and cautious gait. One of the most prevalent forms of dementia in adults is vascular dementia, often caused by multiple small strokes, termed multi-infarct dementia. Strategic infarct dementia, on the other hand, is usually caused by a small, single cerebral infarct. The strategic brain regions specifically involved in post-stroke cognitive impairment requires detailed clinical examination along with radiological imaging for accurate localization. Thus the cognitive impact of ischemic strokes can be understood and predicted by clinicians with the help of maps of strategic brain regions associated with global and domain-specific cognitive functions.

Neural correlates of working memory and compensation at different stages of cognitive impairment in Parkinson’s disease

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PD patients have two types of compensatory mechanisms for working memory (WM).

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First, hyperactivation for different WM load tasks depending on cognitive status.

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PD-CogNL has hyperactivation for moderate and heavy working memory load tasks.

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PD-MCI and PDD have hyperactivation for control and light working memory load tasks.

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Second, bilateral recruitment of WM-related areas improves WM performance.

Working memory (WM) impairment is one of the most frequent cognitive deficits in Parkinson's disease (PD). However, it is not known how neural activity is altered and compensatory responses eventually fail during progression. We aimed to elucidate neural correlates of WM and compensatory mechanisms in PD. Eighteen cognitively normal PD patients (PD-CogNL), 16 with PD with mild cognitive impairment (PD-MCI), 11 with PD with dementia (PDD), and 17 healthy controls (HCs) were evaluated. Subjects performed an n-back task. Functional MRI data were analyzed by event-related analysis for correct responses. Brain activations were evaluated by comparing them to fixation cross or 0-back task, and correlated with n-back task performance. When compared to fixation cross, PD-CogNL patients had more activation in WM areas than HCs for both the 2- and 3-back tasks. PD-MCI and PDD patients had more activation in WM areas than HCs for the 0- and 1-back task. 2-back task performance was correlated with brain activations (vs. 0-back task) in the bilateral dorsolateral prefrontal cortex and frontal eye field (FEF) and left rostral prefrontal cortex, caudate nucleus, inferior/superior parietal lobule (IPL/SPL), and anterior insular cortex as well as anterior cingulate cortex. 3-back task performance was correlated with brain activations (vs. 0-back task) in the left FEF, right caudate nucleus, and bilateral IPL/SPL. Additional activations on top of the 0-back task, rather than fixation cross, are the neural correlates of WM. Our results suggest PD patients have two types of compensatory mechanisms: (1) Hyperactivation for different WM load tasks depending on their cognitive status. PD-CogNL have hyperactivation for moderate and heavy working memory load tasks while maintaining normal working memory performance. In contrast, PD-MCI and PDD have hyperactivation for control task and light working memory load task, leaving less neural resources to further activate for more demanding tasks and resulting in impaired working memory performance. (2) Bilateral recruitment of WM-related areas, in particular the DLPFC, FEF, IPL/SPL and caudate nucleus, to improve WM performance.

Preserved cholinergic forebrain integrity reduces structural connectome vulnerability in mild cognitive impairment

Neurodegeneration leads to redistribution of processing, which is reflected in a reorganisation of the structural connectome. This might affect its vulnerability to structural damage. Cortical acetylcholine allows favourable adaptation to pathology within the memory circuit. However, it remains unclear if it acts on a broader scale, affecting reconfiguration of whole-brain networks. To investigate the role of the cholinergic basal forebrain (CBFB) in strategic lesions, twenty patients with mild cognitive impairment (MCI) and twenty elderly controls underwent magnetic resonance imaging. Whole-brain tractograms were represented as network graphs. Lesions of individual nodes were simulated by removing a node and its connections from the graph. The impact of simulated lesions was quantified as the proportional change in global efficiency. Relationships between subregional CBFB volumes, global efficiency of intact connectomes and impacts of individual simulated lesions of network nodes were assessed. In MCI but not controls, larger CBFB volumes were associated with efficient network topology and reduced impact of hippocampal, thalamic and entorhinal lesions, indicating a protective effect against the global impact of simulated strategic lesions. This suggests that the cholinergic system shapes the configuration of the connectome, thereby reducing the impact of localised damage in MCI.

Predictors of dementia after first ischemic stroke

Various mechanisms contribute to dementia after first ischemic stroke as lesions on strategic areas of cognition and stroke premorbidity.

Objectives

Assessing clinical and neuroimaging predictors of dementia after first ischemic stroke and its relation to stroke location, subtypes and severity.

Methods

Eighty first ischemic stroke patients were included. Forty patients with dementia after first stroke and forty patients without dementia according to DSM-IV diagnostic criteria of vascular dementia. All patients were subjected to general and neurological assessment, National Institute Health Stroke Scale (NIHSS) for stroke severity, Montreal Cognitive Assessment (MoCA) scale for cognition assessment, MRI brain and Trial of Org 10172 in acute stroke treatment (TOAST) classification for stroke subtypes.

Results

Left hemispheric ischemic stroke, strategic infarctions, diabetes mellitus and stroke of anterior circulation were found to be independent risk factors for dementia after first ischemic stroke (OR=3.09, 95%CI 1.67-10.3, OR=2.33, 95%CI 1.87-8.77, OR=1.88, 95%CI 1.44-4.55, OR=1.86, 95%CI 1.45-6.54, respectively). Hypertension, dyslipidemia, smoking, ischemic heart disease, high NIHSS score and large vessel infarction were significantly higher among post stroke dementia patients. However, on binary logistic regression, they did not reach to be independent risk factors.

Conclusion

Stroke location (left stroke, strategic infarction, anterior circulation stroke) and diabetes mellitus could be predictors of dementia after first ischemic stroke, but stroke severity, stroke subtypes, hypertension, dyslipidemia, smoking and ischemic heart could not.

The anterior thalamic nuclei and cognition: A role beyond space?

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Anterior thalamic nuclei important for specific classes of temporal discriminations.

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Anterior thalamic nuclei required for hippocampal-dependent contextual processes.

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Critical role for anterior thalamic nuclei in selective attention.

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Significance of anterior thalamic – anterior cingulate interactions.

The anterior thalamic nuclei are a vital node within hippocampal-diencephalic-cingulate circuits that support spatial learning and memory. Reflecting this interconnectivity, the overwhelming focus of research into the cognitive functions of the anterior thalamic nuclei has been spatial processing. However, there is increasing evidence that the functions of the anterior thalamic nuclei extend beyond the spatial realm. This work has highlighted how these nuclei are required for certain classes of temporal discrimination as well as their importance for processing other contextual information; revealing parallels with the non-spatial functions of the hippocampal formation. Yet further work has shown how the anterior thalamic nuclei may be important for other forms of non-spatial learning, including a critical role for these nuclei in attentional mechanisms. This evidence signals the need to reconsider the functions of the anterior thalamic within the framework of their wider connections with sites including the anterior cingulate cortex that subserve non-spatial functions.

Neuroimaging Research on Dementia in Brazil in the Last Decade: Scientometric Analysis, Challenges, and Peculiarities

The last years have evinced a remarkable growth in neuroimaging studies around the world. All these studies have contributed to a better understanding of the cerebral outcomes of dementia, even in the earliest phases. In low- and middle-income countries, studies involving structural and functional neuroimaging are challenging due to low investments and heterogeneous populations. Outstanding the importance of diagnosing mild cognitive impairment and dementia, the purpose of this paper is to offer an overview of neuroimaging dementia research in Brazil. The review includes a brief scientometric analysis of quantitative information about the development of this field over the past 10 years. Besides, discusses some peculiarities and challenges that have limited neuroimaging dementia research in this big and heterogeneous country of Latin America. We systematically reviewed existing neuroimaging literature with Brazilian authors that presented outcomes related to a dementia syndrome, published from 2010 to 2020. Briefly, the main neuroimaging methods used were morphometrics, followed by fMRI, and DTI. The major diseases analyzed were Alzheimer's disease, mild cognitive impairment, and vascular dementia, respectively. Moreover, research activity in Brazil has been restricted almost entirely to a few centers in the Southeast region, and funding could be the main driver for publications. There was relative stability concerning the number of publications per year, the citation impact has historically been below the world average, and the author's gender inequalities are not relevant in this specific field. Neuroimaging research in Brazil is far from being developed and widespread across the country. Fortunately, increasingly collaborations with foreign partnerships contribute to the impact of Brazil's domestic research. Although the challenges, neuroimaging researches performed in the native population regarding regional peculiarities and adversities are of pivotal importance.

Reduced Self-Awareness Following a Combined Polar and Paramedian Bilateral Thalamic Infarction. A Possible Relationship With SARS-CoV-2 Risk of Contagion?

Reduced self-awareness is a well-known phenomenon investigated in patients with vascular disease; however, its impact on neuropsychological functions remains to be clarified. Importantly, selective vascular lesions provide an opportunity to investigate the key neuropsychological features of reduced self-awareness in neurocognitive disorders. Because of its rarity, we present an unusual case of a woman affected by a combined polar and paramedian bilateral thalamic infarction. The patient underwent an extensive neuropsychological evaluation to assess cognitive, behavioral, and functional domains, with a focus on executive functions. She was assessed clinically in the acute phase and after 6 months from the stroke, both clinically and by magnetic resonance imaging. The patient developed a cognitive impairment, characterised by prevalent executive dysfunction associated with reduced self-awareness and mood changes, in terms of apathy and depression. Such condition persisted after 6 months. In May 2020, the patient underwent the serology test in chemiluminescence to detect IgG antibodies against SARS-CoV-2. The result of the quantitative test highlighted a high probability of previous contact with the virus. We suggest that reduced self-awareness related to executive dysfunction and behavioral changes may be due to combined polar and paramedian bilateral thalamic lesion. Metacognitive–executive dysfunction affecting the instrumental abilities of everyday life might make people less able to take appropriate precautions, facilitating the risk of SARS-CoV-2 contagion.

Network neuroscience of apathy in cerebrovascular disease

Apathy is a reduction in motivated goal-directed behavior (GDB) that is prevalent in cerebrovascular disease, providing an important opportunity to study the mechanistic underpinnings of motivation in humans. Focal lesions, such as those seen in stroke, have been crucial in developing models of brain regions underlying motivated behavior, while studies of cerebral small vessel disease (SVD) have helped define the connections between brain regions supporting such behavior. However, current lesion-based models cannot fully explain the neurobiology of apathy in stroke and SVD. To address this, we propose a network-based model which conceptualizes apathy as the result of damage to GDB-related networks. A review of the current evidence suggests that cerebrovascular disease-related pathology can lead to network changes outside of initially damaged territories, which may propagate to regions that share structural or functional connections. The presentation and longitudinal trajectory of apathy in stroke and SVD may be the result of these network changes. Distinct subnetworks might support cognitive components of GDB, the disruption of which results in specific symptoms of apathy. This network-based model of apathy may open new approaches for investigating its underlying neurobiology, and presents novel opportunities for its diagnosis and treatment.

The role of physical exercise and rehabilitation in delirium

PURPOSE

This article aims to analyze the intersections between delirium, physical exercise and rehabilitation, to better understand their interrelation and to visualize future lines of research.

METHODS

In this narrative review, after an overview of brain neurophysiology and function, as common substrates to understand the relationship between delirium and physical function, we explore the scientific evidence in: (1) physical dysfunction as a risk factor for delirium; (2) physical dysfunction as a symptom of delirium and (3) functional consequences related to delirium. Later, we analyze the physical therapy as one of the main strategies in multicomponent interventions to prevent delirium, by examining intervention studies including rehabilitation, which have shown to be effective in managing delirium. Finally, we analyze how frailty, delirium and physical exercise interact with each other.

RESULTS

This review confirms the close relationship between delirium and physical dysfunction; therefore, it is not surprising that physical exercise is widely used in delirium preventive strategies. Although delirium is catalogued as a neurocognitive disorder, scientific evidence shows that it is also a motor disorder, which is to be expected, since a vast body of literature already supports an interaction between motor and cognitive function.

CONCLUSION

The motor component of delirium should be taken into account when designing interventions or strategies to address delirium. These interventions may have a special importance in frail older adults.

Extent to Which Network Hubs Are Affected by Ischemic Stroke Predicts Cognitive Recovery

Background and Purpose—

It is uncertain what determines the potential for cognitive recovery after ischemic stroke. The extent to which strategic areas of the brain network, so-called hubs, are affected by the infarct could be a key factor. We developed a lesion impact score, which estimates the damage to network hubs by integrating information on infarct size with healthy brain network topology. We verified whether the lesion impact score indeed reflects global network disturbances in patients and assessed if it could predict cognitive recovery.

Methods—

Seventy-five ischemic stroke patients without signs of a prestroke cognitive disorder were included, all with evidence of a cognitive disorder during hospitalization. A brain magnetic resonance imaging and neuropsychological assessment were performed 5 weeks (±1 week) after stroke. Neuropsychological testing was repeated after 1 year to assess cognitive recovery. Brain networks were reconstructed from diffusion-weighted data and consisted of 90 gray matter regions (ie, network nodes). A standard brain network map, indicating the hub-score of each node, was obtained from network data of 44 cognitively healthy adults. For each patient, we calculated the lesion impact score by multiplying the percentage of node volume affected by the infarct with the node’s corresponding hub-score. The patients’ maximum lesion impact score was used as outcome predictor.

Results—

A higher lesion impact score in patients, indicating an increasing infarct size in nodes with a higher hub-score, was related to lower global brain network efficiency (β=−0.528 [−0.776 to −0.277]; P <0.001), independent of age, brain volume, infarct volume, and white matter hyperintensity severity. A lower lesion impact score, however, was an independent predictor of cognitive recovery 1 year after stroke (odds ratio=0.434 [0.193–0.978]; P =0.044).

Conclusions—

We introduced a lesion impact score that combines information on infarct size and network topology to predict long-term recovery after stroke. This score can potentially be used in a clinical setting, also without availability of high-resolution diffusion-weighted magnetic resonance imaging.

Clock drawing and neuroanatomical correlates: A systematic review

OBJECTIVE

The popular clock drawing test (CDT) is easy to administer, acceptable to patients, and has excellent psychometric properties. Although it has been used primarily as a cognitive screening test, many studies have attempted to establish the CDT's ability to localize specific brain lesions or pathology. This systematic review aimed to summarize the evidence on the neuroanatomical correlates of the CDT.

METHODS

Using PRISMA guidelines, the authors systematically reviewed the evidence on neuroanatomical correlates of clock drawing by a systematic search in six databases (Pubmed, CINHL, PsychINFO, HealthStar, Embase, and Web of Science) until January 2018. Studies were included if they reported CDT correlations with anatomical brain lesions documented by neuroimaging.

RESULTS

Forty-five papers met inclusion criteria. Thirty-one studies identified distinct areas of neuroanatomical correlates of CDT utilizing different scoring methods and imaging techniques. Nine articles reported on the degree of white matter hyperintensities that correlated with lower scores on CDT and the severity of cognitive deficits. Five articles focused on postacute cerebrovascular accidents correlated with CDT performance. A variety of different anatomical lesions, located in all areas of the brain, were associated with abnormalities on the CDT.

CONCLUSIONS

The CDT, regardless of scoring method and population studied, was not associated with any consistent, specific brain localization. This systematic review supports the use of the CDT as a cognitive screening test rather than a method of localizing brain lesions.

Severe episodic memory impairment after strategic infarct: A case report

Brain infarcts located in strategic regions often result in cognitive impairment. Based on a case study, this paper describes unusual and specific clinical and neuropsychological features of a strategic ischemic lesion in the left medial temporal lobe (MTL) structures. Taken together with the literature data, the case illustrates that a unilateral strategic infarct in MTL structures may result in severe impairment of episodic memory (EM), which refers to the ability to encode and retrieve personal experiences, including information about the time and place of an event and detailed description of the event itself. The preservation of other cognitive functions, the severe functional impairment, and the type of visual-verbal deficit in a left-sided lesion were identified as singular features of the case. The current case supports the critical role of the MTL structures in EM formation.

A panel of clinical and neuropathological features of cerebrovascular disease through the novel neuroimaging methods

The last decade has witnessed substantial progress in acquiring diagnostic biomarkers for the diagnostic workup of cerebrovascular disease (CVD). Advanced neuroimaging methods not only provide a strategic contribution for the differential diagnosis of vascular dementia (VaD) and vascular cognitive impairment (VCI), but also help elucidate the pathophysiological mechanisms ultimately leading to small vessel disease (SVD) throughout its course.

OBJECTIVE

In this review, the novel imaging methods, both structural and metabolic, were summarized and their impact on the diagnostic workup of age-related CVD was analysed. Methods: An electronic search between January 2010 and 2017 was carried out on PubMed/MEDLINE, Institute for Scientific Information Web of Knowledge and EMBASE.

RESULTS

The use of full functional multimodality in simultaneous Magnetic Resonance (MR)/Positron emission tomography (PET) may potentially improve the clinical characterization of VCI-VaD; for structural imaging, MRI at 3.0 T enables higher-resolution scanning with greater imaging matrices, thinner slices and more detail on the anatomical structure of vascular lesions.

CONCLUSION

Although the importance of most of these techniques in the clinical setting has yet to be recognized, there is great expectancy in achieving earlier and more refined therapeutic interventions for the effective management of VCI-VaD.

Logopenic Aphasia due to a Strategic Stroke: New Evidence from a Single Case

Among primary progressive aphasias (PPAs), logopenic variant PPA (lv-PPA) is usually related to Alzheimer's disease. Although it has been widely clinically and pathologically evaluated, the topography in LPA is still controversial. We report a patient presenting with a logopenic syndrome due to a strategic lesion located in the superior and middle temporal gyrus and compare our findings with those of a PiB-PET positive lv-PPA patient matched by age, gender, and education. We consider that our study provides new anatomical clues to better understand the cognitive mechanisms underlying the logopenic syndrome.

Human anterior thalamic nuclei are involved in emotion-attention interaction

Patients treated with deep brain stimulation (DBS) provide an opportunity to study affective processes in humans with "lesion on demand" at key nodes in the limbic circuitries, such as at the anterior thalamic nuclei (ANT). ANT has been suggested to play a role in emotional control with its connection to the orbitofrontal cortex and the anterior cingulate cortex. However, direct evidence for its role in emotional function in human subjects is lacking. Reported side effects of ANT-DBS in the treatment of refractory epilepsy include depression related symptoms. In line with these mood-related clinical side effects, we have previously reported that stimulating the anterior thalamus increased emotional interference in a visual attention task as indicated by prolonged reaction times due to threat-related emotional distractors. We used event-related potentials to investigate potential attentional mechanism behind this behavioural observation. We hypothesized that ANT-DBS leads to greater attention capture by threat-related distractors. We tested this hypothesis using centro-parietal N2-P3 peak-to-peak amplitude as a measure of allocated attentional resources. Six epileptic patients treated with deep brain stimulation at ANT participated in the study. Electroencephalography was recorded while the patients performed a computer based Executive-Reaction Time test with threat-related emotional distractors. During the task, either ANT or a thalamic control location was stimulated, or the stimulation was turned off. Stimulation of ANT was associated with increased centro-parietal N2-P3 amplitude and increased reaction time in the context of threat-related emotional distractors. We conclude that high frequency electric stimulation of ANT leads to greater attentional capture by emotional stimuli. This is the first study to provide direct evidence from human subjects with on-line electric manipulation of ANT for its role in emotion-attention interaction.

A critical role for the anterior thalamus in directing attention to task-relevant stimuli

The prefrontal cortex mediates adaption to changing environmental contingencies. The anterior thalamic nuclei, which are closely interconnected with the prefrontal cortex, are important for rodent spatial memory, but their potential role in executive function has received scant attention. The current study examined whether the anterior thalamic nuclei are involved in attentional processes akin to those of prefrontal regions. Remarkably, the results repeatedly revealed attentional properties opposite to those of the prefrontal cortex. Two separate cohorts of rats with anterior thalamic lesions were tested on an attentional set-shifting paradigm that measures not only the ability of stimuli dimensions that reliably predict reinforcement to gain attention ("intradimensional shift"), but also their ability to shift attention to another stimulus dimension when contingencies change ("extradimensional shift"). In stark contrast to the effects of prefrontal damage, anterior thalamic lesions impaired intradimensional shifts but facilitated extradimensional shifts. Anterior thalamic lesion animals were slower to acquire discriminations based on the currently relevant stimulus dimension but acquired discriminations involving previously irrelevant stimulus dimensions more rapidly than controls. Subsequent tests revealed that the critical determinant of whether anterior thalamic lesions facilitate extradimensional shifts is the degree to which the stimulus dimension has been established as an unreliable predictor of reinforcement over preceding trials. This pattern of performance reveals that the anterior thalamic nuclei are vital for attending to those stimuli that are the best predictors of reward. In their absence, unreliable predictors of reward usurp attentional control.

Neuroimaging of dementia

Dementia, whether secondary to Alzheimer disease or another process, is a significant cause of morbidity and mortality worldwide. Although dementia remains a clinical diagnosis, for many years imaging has served as a key component in the assessment of patients with cognitive impairment. There have been tremendous advancements in the neuroimaging of dementia over the past decade, moving the field past the rule-out dogma toward ruling in specific pathophysiologic processes. This article is written for the practicing clinician, to provide a review of neuroimaging findings associated with selected degenerative and nondegenerative forms of dementia.

Immediate effects of deep brain stimulation of anterior thalamic nuclei on executive functions and emotion-attention interaction in humans

Background

Deep brain stimulation (DBS) of anterior thalamic nuclei (ANT) is a novel promising therapeutic method for treating refractory epilepsy. Despite reports of subjective memory impairments and mood disturbances in patients with ANT-DBS, little is known of its effects on cognitive and affective processes.

Hypothesis

The anterior thalamus has connections to prefrontal and limbic networks important for cognitive control and emotional reactivity. More specifically, anterior cingulate cortex (ACC), linked with ANT, has been assigned roles related to response inhibition and attention allocation to threat. Thus, we hypothesized ANT-DBS to influence executive functions, particularly response inhibition, and modulate emotional reactivity to threat.

Method

Twelve patients having undergone ANT-DBS for intractable epilepsy participated in the study. Patients performed a computer-based executive reaction time (RT) test—that is, a go/ no-go visual discrimination task with threat-related emotional distractors and rule switching, while the DBS was switched ON (5/5 mA constant current) and OFF every few minutes.

Results

ANT-DBS increased the amount of commission errors—that is, errors where subjects failed to withhold from responding. Furthermore, ANT-DBS slowed RTs in context of threat-related distractors. When stimulation was turned off, threat-related distractors had no distinct effect on RTs.

Conclusion

We found immediate objective effects of ANT-DBS on human cognitive control and emotion-attention interaction. We suggest that ANT-DBS compromised response inhibition and enhanced attention allocation to threat due to altered functioning of neural networks that involve the DBS-target, ANT, and the regions connected to it such as ACC. The results highlight the need to consider affective and cognitive side-effects in addition to the therapeutic effect when adjusting stimulation parameters. Furthermore, this study introduces a novel window into cognitive and affective processes by modulating the associative and limbic networks with direct stimulation of key nodes in the thalamus.

Transcranial magnetic stimulation for the treatment of pharmacoresistant nondelusional auditory verbal hallucinations in dementia

Auditory verbal hallucinations (AVHs) are known as a core symptom of schizophrenia, but also occur in a number of other conditions, not least in neurodegenerative disorders such as dementia. In the last decades, Transcranial Magnetic Stimulation (TMS) emerged as a valuable therapeutic approach towards several neurological and psychiatric diseases, including AVHs. Herein we report a case of a seventy-six-years-old woman with vascular-degenerative brain disease, complaining of threatening AVHs. The patient was treated with a high-frequency temporoparietal (T3P3) rTMS protocol for fifteen days. A considerable reduction of AVHs in frequency and content (no more threatening) was observed. Although further research is needed, this seems an encouraging result.