Aaron D Boes

• MD, PhD
• Professor (Associate) at University of Iowa

Predicting long-term functional outcomes for individuals with stroke is a significant challenge. Solving this challenge will open new opportunities for improving stroke management by informing acute interventions and guiding personalized rehabilitation strategies. The location of the stroke is a key predictor of outcomes, yet no clinically deployed...

Transcranial magnetic stimulation (TMS) to the dorsolateral prefrontal cortex (DLPFC) is hypothesized to relieve symptoms of depression by inhibiting activity in the subgenual anterior cingulate cortex (sgACC). However, we have a limited understanding of how TMS influences neural activity in the sgACC, owing to its deep location within the brain. T...

Recent studies combining transcranial magnetic stimulation (TMS) with intracranial EEG (iEEG) have significantly advanced our understanding of neural circuits and the effects of exogenous stimulation upon them. These studies leverage the high spatial and temporal resolution of iEEG to illuminate the multifaceted and dynamic aspects of TMS-associate...

Objective Dystonia is a movement disorder defined by involuntary muscle contractions leading to abnormal postures or twisting and repetitive movements. Classically dystonia has been thought of as a disorder of the basal ganglia, but newer results in idiopathic dystonia and lesion‐induced dystonia in adults point to broader motor network dysfunction...

Transcranial magnetic stimulation (TMS) has emerged as a powerful clinical tool for treating neuropsychiatric conditions, yet our understanding of how TMS modulates neural circuits in the human brain remains limited. While decades of research have established the therapeutic efficacy of TMS, fundamental questions persist about the spatial and tempo...

Over the past 30 years, mindfulness meditation (MM) has gained popularity as a cognitive strategy in therapies aimed at impulse control and behavioral or emotional regulation for various mental health challenges. Despite this, evidence supporting its effectiveness, as well as a clear understanding of its underlying autonomic and neurophysiological...

Transcranial magnetic stimulation combined with intracranial local field potential recordings in humans (TMS-iEEG) represents a new method for investigating electrophysiologic effects of TMS with spatiotemporal precision. We applied TMS-iEEG to the dorsolateral prefrontal cortex (dlPFC) in two subjects and demonstrate evoked activity in the subgenu...

Low-intensity Transcranial Ultrasound Stimulation (TUS) is a promising non-invasive technique for deep-brain stimulation and focal neuromodulation. Research with animal models and computational modelling has raised the possibility that TUS can be biased towards enhancing or suppressing neural function. Here, we first conduct a systematic review of...

Low-intensity Transcranial Ultrasound Stimulation (TUS) is a promising non-invasive technique for deep-brain stimulation and focal neuromodulation. Research with animal models and computational modelling has raised the possibility that TUS can be biased towards enhancing or suppressing neural function. Here, we first conduct a systematic review of...

Disorders of consciousness (DoC) are states of impaired arousal or awareness. Deep brain stimulation (DBS) is a potential treatment, but outcomes vary, possibly due to differences in patient characteristics, electrode placement, or stimulation of specific brain networks. We studied 40 patients with DoC who underwent DBS targeting the thalamic centr...

Temporal lobe (TL) epilepsy surgery is an effective treatment option for patients with drug-resistant epilepsy. However, neurosurgery poses a risk for cognitive deficits - up to one third of patients have a decline in naming ability following TL surgery. In this study, we aimed to better understand the neural correlates associated with reduced nami...

Religious fundamentalism, characterized by rigid adherence to a set of beliefs putatively revealing inerrant truths, is ubiquitous across cultures and has a global impact on society. Understanding the psychological and neurobiological processes producing religious fundamentalism may inform a variety of scientific, sociological, and cultural questio...

The traditional analytical framework taken by neuroimaging studies in general, and lesion-behavior studies in particular, has been inferential in nature and has focused on identifying and interpreting statistically significant effects within the sample under study. While this framework is well-suited for hypothesis testing approaches, achieving the...

Chronic motor impairments are a leading cause of disability after stroke. Previous studies have associated motor outcomes with the degree of damage to predefined structures in the motor system, such as the corticospinal tract. However, such theory-based approaches may not take full advantage of the information contained in clinical imaging data. Th...

Low-intensity Transcranial Ultrasound Stimulation (TUS) is a promising non-invasive technique for deep-brain stimulation and focal neuromodulation. Research with animal models and computational modelling has raised the possibility that TUS can be biased towards enhancing or suppressing neural function. Here, we first conduct a systematic review of...

Background Transcranial magnetic stimulation (TMS) is believed to alter ongoing neural activity and cause circuit-level changes in brain function. While the electrophysiological effects of TMS have been extensively studied with scalp electroencephalography (EEG), this approach generally evaluates low-frequency neural activity at the cortical surfac...

Objective: Dystonia is a movement disorder defined by involuntary muscle contractions leading to abnormal postures or twisting and repetitive movements. Classically dystonia has been thought of as a disorder of the basal ganglia, but newer results in idiopathic dystonia and lesion-induced dystonia in adults point to broader motor network dysfunctio...

Transcranial magnetic stimulation (TMS) is increasingly used as a noninvasive technique for neuromodulation in research and clinical applications, yet its mechanisms are not well understood. Here, we present the neurophysiological effects of TMS using intracranial electrocorticography (iEEG) in neurosurgical patients. We first evaluated safety in a...

Objective Stroke is a prevalent disease and often produces cognitive impairment. Post-stroke cognitive impairment has been associated with challenges returning to interpersonal and occupational activities. Knowing what factors are associated with cognitive impairment post-stroke can be useful for predicting outcomes and guiding rehabilitation strat...

Objective General cognitive ability (g) is central to our understanding of human cognition, as it accounts for nearly half of individual differences in performances on diverse cognitive tests. There is growing interest in the brain networks necessary for g because such knowledge could elucidate neural mechanisms of g. Prior work highlighted the ass...

Background Widely reported by bipolar disorder (BD) patients, cognitive symptoms, including deficits in executive function, memory, attention, and timing are under-studied. Work suggests that individuals with BD show impairments in interval timing tasks, including supra-second, sub-second, and implicit motor timing compared to the neuronormative po...

Objectives To evaluate what factors influence naming ability after temporal lobectomy in patients with drug-resistant epilepsy. Methods 85 participants with drug-resistant epilepsy who underwent temporal lobe (TL) resective surgery were retrospectively identified (49 left TL and 36 right TL). Naming ability was assessed before and >3 months post-s...

Background The Beam F3 and 5.5 cm methods are the two most common targeting strategies for localizing the left dorsolateral prefrontal cortex (DLPFC) treatment site in repetitive transcranial magnetic stimulation (rTMS) protocols. This prospective, randomized, double-blind comparative effectiveness trial assesses the clinical outcomes for these two...

Understanding central auditory processing critically depends on defining underlying auditory cortical networks and their relationship to the rest of the brain. We addressed these questions using resting state functional connectivity derived from human intracranial electroencephalography. Mapping recording sites into a low-dimensional space where pr...

Transcranial magnetic stimulation (TMS) is increasingly deployed in the treatment of neuropsychiatric illness, under the presumption that stimulation of specific cortical targets can alter ongoing neural activity and cause circuit-level changes in brain function. While the electrophysiological effects of TMS have been extensively studied with scalp...

Chronic motor impairments are a leading cause of disability after stroke. Previous studies have predicted motor outcomes based on the degree of damage to predefined structures in the motor system, such as the corticospinal tract. However, such theory-based approaches may not take full advantage of the information contained in clinical imaging data....

Multivariate autoregressive (MVAR) model estimation enables assessment of causal interactions in brain networks. However, accurately estimating MVAR models for high-dimensional electrophysiological recordings is challenging due to the extensive data requirements. Hence, the applicability of MVAR models for study of brain behavior over hundreds of r...

Background: Widely reported by bipolar disorder (BD) patients, cognitive symptoms, including deficits in executive function, memory, attention, and timing are under-studied. Work suggests that individuals with BD show impairments in interval timing tasks, including supra-second, sub-second, and implicit motor timing compared to the neuronormative...

Approximately 25% of pediatric patients who undergo cerebellar tumor resection develop cerebellar mutism syndrome (CMS). Our group recently showed that damage to the cerebellar deep nuclei and superior cerebellar peduncles, which we refer to as the cerebellar outflow pathway, is associated with increased risk of CMS. Here, we tested whether these f...

Objective: Time orientation is a fundamental cognitive process in which one's personal sense of time is matched with a universal reference. Time orientation is commonly assessed through mental status examination, yet its neural correlates remain unclear. Large lesions have been associated with deficits in time orientation, but the regional anatomy...

Cognitive control modulates other cognitive functions to achieve internal goals and is important for adaptive behavior. Cognitive control is enabled by the neural computations distributed over cortical and subcortical areas. However, due to technical challenges in recording neural activity from the white matter, little is known about the anatomy of...

This case report highlights a possible consequence of damage to the left frontoinsular region. A 53-year-old woman with chronic obesity and headaches presented with seizure, leading to the discovery and resection of a large sphenoid wing meningioma. Postoperative brain imaging revealed loss of the left frontoinsular cortex and portions of the under...

These authors contributed equally to this work. Stroke significantly impacts the quality of life. However, the long-term cognitive evolution in stroke is poorly predictable at the individual level. There is an urgent need to better predict long-term symptoms based on acute clinical neu-roimaging data. Previous works have demonstrated a strong relat...

Theories of the relation between age at lesion onset and outcomes posit different views of the young brain: resilient and plastic (i.e., the so-called "Kennard Principle"), or vulnerable (i.e., the Early Vulnerability Hypothesis). There is support for both perspectives in previous research and questions about the "best" or "worst" times to sustain...

Neuroimaging studies in healthy and clinical populations strongly associate the amygdala with emotion, especially negative emotions. The consequences of surgical resection of the amygdala on mood are not well characterized. We tested the hypothesis that amygdala resection would result in mood improvement. In this study, we evaluated a cohort of 52...

Objective Stroke can cause cognitive impairment, which can lead to challenges returning to day-to-day activities. Knowing what factors are associated with cognitive impairment post-stroke can be useful for predicting outcomes and guiding rehabilitation. One such factor is gender: previous studies are inconclusive as to whether gender influences cog...

Background and Objectives Approximately 25% of pediatric patients who undergo cerebellar tumor resection develop cerebellar mutism syndrome (CMS). Our group recently showed that damage to the cerebellar outflow pathway is associated with increased risk of CMS. Here, we tested whether these findings replicate in an independent cohort. Methods We eva...

Non-invasive Gamma ENtrainment Using Sensory stimulation (GENUS) at 40Hz reduces Alzheimer’s disease (AD) pathology such as amyloid and tau levels, prevents cerebral atrophy, and improves behavioral testing performance in mouse models of AD. Here, we report data from (1) a Phase 1 feasibility study (NCT04042922, ClinicalTrials.gov) in cognitively n...

Research Objectives To develop a model to predict specific cognitive impairments following stroke based on the lesion's white matter edge density and location with respect to the left posterior arcuate fasciculus. Design Retrospective observational cohort study. Setting University medical center, inpatient and outpatient. Participants 149 adults...

Neuroimaging studies in healthy and clinical populations strongly associate the amygdala with emotion, especially negative emotions. The consequences of surgical lesions of the amygdala on mood are not well characterized. We tested the hypothesis that amygdala lesions would result in mood improvement. In this study we evaluated a cohort of 52 indiv...

Multivariate autoregressive (MVAR) model estimation enables assessment of causal interactions in brain networks. However, accurately estimating MVAR models for high-dimensional electrophysiological recordings is challenging due to the extensive data requirements. Hence, the applicability of MVAR models for study of brain behavior over hundreds of r...

Autonomic dysfunction has been described in patients with Huntington’s Disease, but it is unclear if these changes in autonomic tone are related to the central autonomic network. We performed a pilot study to investigate the relationship between the integrity of the central autonomic network and peripheral manifestiations of autonomic dysfunction i...

Understanding neural circuits that support mood is a central goal of affective neuroscience, and improved understanding of the anatomy could inform more targeted interventions in mood disorders. Lesion studies provide a method of inferring the anatomical sites causally related to specific functions, including mood. Here, we perform a large-scale st...

Objectives: Though widely reported by patients, cognitive symptoms associated with bipolar disorder (BD), including deficits in executive function, memory, attention, and timing are under-studied. Work suggests that individuals with BD show impairments in sub-second interval timing tasks (ITT), however, results have been inconclusive regarding supr...

Introduction: Examining depression following neurological injury is useful for understanding post-lesion depression and depression more generally. The extant literature shows variability in the incidence and severity of depression post-lesion, likely due to heterogeneity in study methodology, patient samples, measures of depression, and time of as...

Strokes cause lesions that damage brain tissue, disrupt normal brain activity patterns and can lead to impairments in motor function. Although modulation of cortical activity is central to stimulation-based rehabilitative therapies, aberrant and adaptive patterns of brain activity after stroke have not yet been fully characterized. Here, we apply a...

The functional roles of the precuneus are unclear. Focal precuneus lesions are rare, making it difficult to identify robust brain–behavior relationships. Distinct functional subdivisions of the precuneus have been proposed based on unique connectivity profiles. This includes an association of the anterior division with bodily awareness, the central...

Wakefulness is necessary for consciousness, and impaired wakefulness is a symptom of many diseases. The neural circuits that maintain wakefulness remain incompletely understood, as do the mechanisms of impaired consciousness in many patients. In contrast to the influential concept of a diffuse “reticular activating system,” the past century of neur...

Background Treatment resistant depression is common in older adults and treatment is often complicated by medical comorbidities and polypharmacy. Repetitive transcranial magnetic stimulation (rTMS) is a treatment option for this group due to its favorable profile. However, early influential studies suggested that rTMS is less effective in older adu...

Historically, topological lesion-based studies have provided a direct way to map brain regions to their corresponding functions; however, these approaches fail to consider the impact of the lesion on broader brain networks. Focus has shifted in the latter half of the nineteenth century from topological to hodological, or network-based, approaches t...

Drug addiction is a public health crisis for which new treatments are urgently needed. In rare cases, regional brain damage can lead to addiction remission. These cases may be used to identify therapeutic targets for neuromodulation. We analyzed two cohorts of patients addicted to smoking at the time of focal brain damage (cohort 1 n = 67; cohort 2...

Background and Objectives Time orientation is a fundamental cognitive process in which one’s personal sense of time is matched with a universal reference. Assessment of time orientation is a ubiquitous component of neurological mental status examinations and neuropsychological assessments, yet its neural correlates remain unclear. Large bilateral l...

Posterior fossa arachnoid cysts (PFACs) are rare congenital abnormalities observed in 0.3 to 1.7% of the population and are traditionally thought to be benign. While conducting a neuroimaging study investigating cerebellar structure in bipolar disorder, we observed a higher incidence of PFACs in bipolar patients (5 of 75; 6.6%) compared to the neur...

No PDF available ABSTRACT Listeners face the challenge of understanding speech every day. A key cognitive strategy for parsing speech in noisy environments relies on auditory selective attention, which recruits a network of multiple cortical regions. Our recent studies identified at least two different neural mechanisms of auditory attention. Space...

Background: Results reported in the existing literature have shown intermittent theta burst stimulation (iTBS) to be noninferior to 10 Hz repetitive transcranial magnetic stimulation (rTMS) in treating major depressive disorder (MDD) when targeted at the left dorsolateral prefrontal cortex. The goal of this naturalistic observational study was to...

Critical details remain unresolved about the organization of the human auditory cortical hierarchy and its relationship to higher order brain networks. We investigated this organization using diffusion map embedding (DME) applied to resting state intracranial electroencephalography (iEEG) obtained in neurosurgical patients. DME was applied to funct...

The upper brainstem tegmentum is dense and complex, making it difficult to localize functions to specific subregions. In particular, the precise location and possible laterality of subregions supporting basic functions like consciousness and urinary continence remain unclear. Here, we describe a patient who presented with a right pontine tegmental...

Strokes cause lesions that damage brain tissue, disrupt normal brain activity patterns, and can lead to impairments in cognition and motor function. Although modulation of cortical activity is central to stimulation-based rehabilitative therapies, aberrant and adaptive patterns of brain activity after stroke have not yet been fully characterized. H...

Understanding central auditory processing critically depends on defining underlying auditory cortical networks and their relationship to the rest of the brain. We addressed these questions using resting state functional connectivity derived from human intracranial electroencephalography. Mapping recording sites into a low-dimensional space where pr...

Transcranial magnetic stimulation (TMS) is increasingly used as a noninvasive technique for neuromodulation in research and clinical applications, yet its mechanisms are not well understood. Here, we present the first in-human study evaluating the effects of TMS using intracranial electrocorticography (iEEG) in neurosurgical patients. We first eval...

Clinicians and scientists alike have long sought to predict the course and severity of chronic post-stroke cognitive and motor outcomes, as the ability to do so would inform treatment and rehabilitation strategies. However, it remains difficult to make accurate predictions about chronic post-stroke outcomes due, in large part, to high inter-individ...

“Frontal lobe syndrome” is a term often used to describe a diverse array of personality disturbances following frontal lobe damage. This study’s guiding premise was that greater neuroanatomical specificity could be achieved by evaluating specific types of personality disturbances following acquired frontal lobe lesions. We hypothesized that three a...

Motor recovery following ischemic stroke is contingent on the ability of surviving brain networks to compensate for damaged tissue. In rodent models, sensory and motor cortical representations have been shown to remap onto intact tissue around the lesion site, but remapping to more distal sites (e.g. in the contralesional hemisphere) has also been...

Hubs in the human brain support behaviors that arise from brain network interactions. Previous studies have identified hub regions in the human thalamus that are connected with multiple functional networks. However, the behavioral significance of thalamic hubs has yet to be established. Our framework predicts that thalamic subregions with strong hu...

Motor recovery following ischemic stroke is contingent on the ability of surviving brain networks to compensate for damaged tissue. In rodent models, sensory and motor cortical representations have been shown to remap onto intact tissue around the lesion site, but remapping to more distal sites (e.g. in the contralesional hemisphere) has also been...

Psychiatric conditions are common and often disabling. Although great strides have been made in alleviating symptoms with pharmacotherapy and psychotherapeutic approaches, many patients continue to have severe disease burden despite the best therapies available. One of the pervasive challenges to improving treatment is that present diagnostic and t...

Significance Hubs are highly connected brain regions that are important for coordinating processing in brain networks and supporting cognition. There are several different methods for characterizing network hubs in gray and white matter, yet it is unclear which of these hub measures identify sites that are most critical for supporting cognition. He...

Hubs in the human brain support behaviors that arise from brain network interactions. Previous studies have identified hub regions in the human thalamus that are connected with multiple functional networks. However, the behavioral significance of thalamic hubs has yet to be established. Our framework predicts that thalamic subregions with strong hu...

Non-invasive G amma EN trainment U sing S ensory stimulation (GENUS) at 40Hz reduced Alzheimer’s disease (AD) pathology such as amyloid and tau levels, prevented cerebral atrophy and improved performance during behavioral testing in mouse models of AD. We report data from a randomized, placebo-controlled trial (n = 15) in volunteers with probable m...

The extent of disruption to the corticospinal tract has been associated with motor impairment and worse recovery, but the role of other motor and sensorimotor tracts in impairment following brainstem stroke is poorly understood. Additionally, the impact of brainstem strokes on connectivity to distal cortical regions innervated by these tracts has n...

The human thalamus has been suggested to be involved in executive function, based on animal studies and correlational evidence from functional neuroimaging in humans. Human lesion studies, examining behavioral deficits associated with focal brain injuries, can directly test the necessity of the human thalamus for executive function. The goal of our...

Background Our lab previously showed that 40 Hz sensory stimulation can modulate neural oscillations, ameliorate Alzheimer’s disease (AD) pathology, and improve cognition in AD mouse models (Iaccarino, Singer et al., Nature , 2016; Martorell, Paulson et al., Cell , 2019; Adaikkan et al., Neuron , 2019). To determine the safety and feasibility of 40...

General cognitive ability – or general intelligence (g) – is central to cognitive science, yet the processes that constitute it remain unknown, in good part because most prior work has relied on correlational methods. Large-scale behavioral and neuroanatomical data from neurological patients with focal brain lesions can be leveraged to advance our...

There is controversy regarding the unique contributions of the right and left hemispheres for human cognition. The right hemisphere is thought to play an important role in “nonverbal” cognitive abilities, such as visuospatial processing. ¹ However, the necessity of the right hemisphere for other aspects of cognition has been challenged by the relat...

Transcranial Magnetic Stimulation (TMS) is a method of non-invasively modulating the excitability of the brain. TMS relies on the principle of electromagnetic induction in producing an electric field that stimulates neurons. Measuring the effect of TMS in real time and being able to determine its spatiotemporal resolution increase its potential in...

Rapid eye movement (REM) sleep is a paradoxical state where the individual appears asleep while the electroencephalogram pattern resembles that of wakefulness. Regional differences in brain metabolism have been observed during REM sleep compared to wakefulness, but it is not known whether the spatial distribution of metabolic differences correspond...

Functional neuroimaging research has consistently associated brain structures within the default mode network (DMN) and frontoparietal network (FPN) with mind‐wandering. Targeted lesion research has documented impairments in mind‐wandering after damage to the medial prefrontal cortex (mPFC) and hippocampal regions associated with the DMN. However,...