Prefrontal Activation During Inhibition of a Balance Recovery Step

The ability to quickly step is an important strategy to avoid a fall. However, real-world settings often constrain a stepping path. Such constraints necessitate response inhibition to prevent an inappropriate step and select a new course of action to ultimately recover balance. The present study investigated neural mechanisms that underlie this ability to stop a highly automatic balance recovery step. In the field of cognitive neuroscience, response inhibition has typically been researched using focal hand reaction tasks performed by seated participants. This approach combined with neuroimaging has revealed a neural stopping network, which includes the right Inferior Frontal Gyrus (right IFG) as a key node in this network. It is unclear if the same brain-based stopping networks suppress a prepotent balance reaction since compensatory balance reactions are subcortically triggered, multi-segmental responses that are much faster than voluntary reactions. To test this, functional near-infrared spectroscopy (fNIRS) was used to measure brain activity in 21 young adults (ages 18-30) as they performed a balance recovery task that demanded rapid step suppression following postural perturbation. The hypothesis was that the right IFG would show heightened activity when suppressing an automatic balance recovery step. A lean and-release system was used to impose temporally unpredictable forward perturbations by releasing participants from a supported forward lean. For most trials (80%), participants were told to recover balance by quickly stepping forward. However, on 20% of trials at random, a high-pitch tone was played immediately after postural perturbation signaling participants to suppress a step and fully relax into a catch harness. This allowed us to target the ability to cancel an already initiated step in a balance recovery context. Average Oxygenated hemoglobin (HbO2) changes were contrasted between step and stop trials, 1-6 seconds post perturbation. A two-way repeated measures ANOVA tested for main effects with condition 4 (Step, Stop), and hemisphere (right, left) and for the interaction. Post hoc analysis was performed using paired t-test comparisons between Step and Stop trials for each channel (Bonferroni correction applied). Two-way, repeated measures ANOVA showed no significant interaction (F1, 20 = 1.212, p = 0.284) between factors and no significant main effect for hemisphere (F1, 20 = 0.282, p = 0.601). However, there was a significant main effect for condition where Stop trials produced a greater response compared to Step trials (F1, 20 = 31.617, p \u3c 0.001). Follow-up analysis revealed a significant increase in three of the seven channels on each hemisphere. Consistent with the hypothesis, the results showed a greater prefrontal response during stopping trials, supporting the idea that executive brain networks are active when suppressing a balance recovery step. Contrary to our hypothesis, a similar increased response for stop trials was observed in both hemispheres indicating that step suppression was not limited to right IFG control, at least not as currently measured. This study demonstrates one way in which higher brain processes may help us prevent falls in complex environments where behavioral flexibility is necessary. This study also presents a novel method for assessing response inhibition in an upright postural context where rapid stepping reactions are required

Contributions of Human Prefrontal Cortex to the Recogitation of Thought

Human beings have a unique ability to not only verbally articulate past and present experiences, as well as potential future ones, but also evaluate the mental representations of such things. Some evaluations do little good, in that they poorly reflect facts, create needless emotional distress, and contribute to the obstruction of personal goals, whereas some evaluations are the converse: They are grounded in logic, empiricism, and pragmatism and, therefore, are functional rather than dysfunctional. The aim of non-pharmacological mental health interventions is to revise dysfunctional thoughts into more adaptive, healthier ones; however, the neurocognitive mechanisms driving cognitive change have hitherto remained unclear. Therefore, this thesis examines the role of the prefrontal cortex (PFC) in this aspect of human higher cognition using the relatively new method of functional near-infrared spectroscopy (fNIRS). Chapter 1 advances recogitation as the mental ability on which cognitive restructuring largely depends, concluding that, as a cognitive task, it is a form of open-ended human problem-solving that uses metacognitive and reasoning faculties. Because these faculties share similar executive resources, Chapter 2 discusses the systems in the brain involved in controlled information processing, specifically the nature of executive functions and their neural bases. Chapter 3 builds on these ideas to propose an information-processing model of recogitation, which predicts the roles of different subsystems localized within the PFC and elsewhere in the context of emotion regulation. This chapter also highlights several theoretical and empirical challenges to investigating this neurocognitive theory and proposes some solutions, such as to use experimental designs that are more ecologically valid. Chapter 4 focuses on a neuroimaging method that is best suited to investigating questions of spatial localization in ecological experiments, namely functional near-infrared spectroscopy (fNIRS). Chapter 5 then demonstrates a novel approach to investigating the neural bases of interpersonal interactions in clinical settings using fNIRS. Chapter 6 explores physical activity as a ‘bottom-up’ approach to upregulating the PFC, in that it might help clinical populations with executive deficits to regulate their mental health from the ‘top-down’. Chapter 7 addresses some of the methodological issues of investigating clinical interactions and physical activity in more naturalistic settings by assessing an approach to recovering functional events from observed brain data. Chapter 8 draws several conclusions about the role of the PFC in improving psychological as well as physiological well-being, particularly that rostral PFC is inextricably involved in the cognitive effort to modulate dysfunctional thoughts, and proposes some important future directions for ecological research in cognitive neuroscience; for example, psychotherapy is perhaps too physically stagnant, so integrating exercise into treatment environments might boost the effectiveness of intervention strategies

Response variability in Attention-Deficit/Hyperactivity Disorder: a neuronal and glial energetics hypothesis

BACKGROUND: Current concepts of Attention-Deficit/Hyperactivity Disorder (ADHD) emphasize the role of higher-order cognitive functions and reinforcement processes attributed to structural and biochemical anomalies in cortical and limbic neural networks innervated by the monoamines, dopamine, noradrenaline and serotonin. However, these explanations do not account for the ubiquitous findings in ADHD of intra-individual performance variability, particularly on tasks that require continual responses to rapid, externally-paced stimuli. Nor do they consider attention as a temporal process dependent upon a continuous energy supply for efficient and consistent function. A consideration of this feature of intra-individual response variability, which is not unique to ADHD but is also found in other disorders, leads to a new perspective on the causes and potential remedies of specific aspects of ADHD. THE HYPOTHESIS: We propose that in ADHD, astrocyte function is insufficient, particularly in terms of its formation and supply of lactate. This insufficiency has implications both for performance and development: H1) In rapidly firing neurons there is deficient ATP production, slow restoration of ionic gradients across neuronal membranes and delayed neuronal firing; H2) In oligodendrocytes insufficient lactate supply impairs fatty acid synthesis and myelination of axons during development. These effects occur over vastly different time scales: those due to deficient ATP (H1) occur over milliseconds, whereas those due to deficient myelination (H2) occur over months and years. Collectively the neural outcomes of impaired astrocytic release of lactate manifest behaviourally as inefficient and inconsistent performance (variable response times across the lifespan, especially during activities that require sustained speeded responses and complex information processing). TESTING THE HYPOTHESIS: Multi-level and multi-method approaches are required. These include: 1) Use of dynamic strategies to evaluate cognitive performance under conditions that vary in duration, complexity, speed, and reinforcement; 2) Use of sensitive neuroimaging techniques such as diffusion tensor imaging, magnetic resonance spectroscopy, electroencephalography or magnetoencephalopathy to quantify developmental changes in myelination in ADHD as a potential basis for the delayed maturation of brain function and coordination, and 3) Investigation of the prevalence of genetic markers for factors that regulate energy metabolism (lactate, glutamate, glucose transporters, glycogen synthase, glycogen phosphorylase, glycolytic enzymes), release of glutamate from synaptic terminals and glutamate-stimulated lactate production (SNAP25, glutamate receptors, adenosine receptors, neurexins, intracellular Ca(2+)), as well as astrocyte function (α(1), α(2 )and β-adrenoceptors, dopamine D1 receptors) and myelin synthesis (lactate transporter, Lingo-1, Quaking homolog, leukemia inhibitory factor, and Transferrin). IMPLICATIONS OF THE HYPOTHESIS: The hypothesis extends existing theories of ADHD by proposing a physiological basis for specific aspects of the ADHD phenotype – namely frequent, transient and impairing fluctuations in functioning, particularly during performance of speeded, effortful tasks. The immediate effects of deficient ATP production and slow restoration of ionic gradients across membranes of rapidly firing neurons have implications for daily functioning: For individuals with ADHD, performance efficacy would be enhanced if repetitive and lengthy effortful tasks were segmented to reduce concurrent demands for speed and accuracy of response (introduction of breaks into lengthy/effortful activities such as examinations, motorway driving, assembly-line production). Also, variations in task or modality and the use of self- rather than system-paced schedules would be helpful. This would enable energetic demands to be distributed to alternate neural resources, and energy reserves to be re-established. Longer-term effects may manifest as reduction in regional brain volumes since brain areas with the highest energy demand will be most affected by a restricted energy supply and may be reduced in size. Novel forms of therapeutic agent and delivery system could be based on factors that regulate energy production and myelin synthesis. Since the phenomena and our proposed basis for it are not unique to ADHD but also manifests in other disorders, the implications of our hypotheses may be relevant to understanding and remediating these other conditions as well

The Effect Of Body Position On Cerebral Bllod Flow, Cognition, Cardiac Output, Map,and Motor Function In Patients Undergoing Shoulder Surgery : Lateral Versus Beach Chair Position Under General Anesthesia

ABSTRACT The Effect of Body Position on Changes in Cerebral Blood Flow, Cognition, and Motor Function in Patients Undergoing Shoulder Surgery: Lateral versus Beach Chair Position Under General Anesthesia By KELLEY LABONTY December 2013 Advisor: Dr. Steven Cala Major: Physiology Degree: Doctor of Philosophy This study aims to determine if there are alterations in cerebral perfusion in patients undergoing general anesthesia in the sitting position. With the reporting of 15 catastrophic cerebral vascular accidents recently being published during shoulder surgery in the sitting position, an increase of 90 times from previously reported data, there has become a clear need for immediate research in this area. A peri-operative stroke has a 60% incidence of morbidity versus 15-46% for strokes in general. This is a devastating outcome for families, physicians and all involved. Current literature points to the sitting position as being a significant risk factor for decreasing cerebral perfusion. Surgeons utilize this position for ease of surgery and may request deliberate hypotension to decrease bleeding and increase visualization at the surgical site. It is unclear whether deliberate hypotension, inadvertent hypotension, air embolus, spinal cord stretching, or neck vessel stretching are key factors involved. An area of concern is that the blood pressure recorded in the arm of the patient in the sitting position is significantly less than that in the brain, this in addition to the decrease in cardiac output while sitting, and vasodilation of the general anesthetics all create the perfect storm to offset normal autoregulatory responses. Interestingly, the brain is the least monitored organ under anesthesia. It is evident that this practice requires re-evaluation. With the invent of numerous non-invasive cerebral perfusion devices being cited in the literature as very useful in monitoring cerebral perfusion, it is important that we utilize this technology to provide safe patient care and improved outcomes. Devices such as the Cerebral Oximeter and non-invasive cardiac output monitorcan provide relevant information and may aid in preventing these catastrophic events. It is our goal to implement these monitors in patients undergoing general anesthesia in the sitting and lateral decubitus position to evaluate their effectiveness in alerting the anesthesia provider to decreases in cerebral perfusion and improving patient outcomes. Secondly, with the concomitant use of these two devices, we may be better able to understand the physiological role of cerebral perfusion in the sitting position and gain insight as to the cause of the cerebral vascular events and patients at risk. In addition, the S-100 lab test is a peripheral marker of glial injury and has been shown to correlate well with brain injury. It is our belief that this lab test is underutilized and may be very beneficial in these cases. Research shows elevation of this marker two days post operatively is indicative of a shorter life expectancy regardless of any known cerebral complications. Lastly, although MRI\u27s and CT Scans can detect brain abnormalities, they cannot assess brain function. Neuro-cognitive testing on the other hand has been shown to reliably evaluate brain function and will be implemented at three different times in this study to correlate with monitoring and lab data obtained peri-operatively.. Methods: 100 patients age 18-65 years old will be included in the study. They will receive a general anesthetic in the beach chair or lateral decubitus position for shoulder surgery. Baseline neurocognitive testing will be done along with cardiac output, cerebral oxygenation, and s-100 lab values. A standard anesthetic protocol will be followed for all patients. Continuous monitoring of CO and cerebral oximetry will be utilized throughout each case. Post-operatively the S-100 lab will be repeated and again at 24 hours followed by neurocognitive testing. The final neuro-cognitive test will be completed at the 6 week post operative follow up visit. The goal of this study is to determine whether conducting shoulder surgery in the beach chair position causes neurocognitive changes in patients when compared with those undergoing surgery in the lateral decubitus position. Specific aims 1. To determine whether the regional oxygen saturation in the brain is diminished during shoulder surgery in the beach chair position using near infrared spectroscopy. 2. To determine whether there is a significant change in cardiac output and MAP in the beach chair position versus the lateral decubitus position using a non invasive cardiac output monitor. 3. To determine if there are neurocognitive injuries associated with sitting and lateral positions by examining the S-100 Beta levels and neurocognitive evaluations of patients before and after surgery. We hypothesize that cerebral perfusion is decreased in patients undergoing surgery in the sitting position due to a combination of decreased cardiac output, vasodilation and higher lower limits of cerebral autoregulation. We believe this decrease in cerebral perfusion will be seen by the cerebral oximeter. We also predict that the S-100 B lab test will be sensitive enough to pick up significant changes in cerebral perfusion

An examination of conceptual knowledge using near-infrared spectroscopy and electroencephalography

Traditionally, models of conceptual knowledge have relied upon amodal theories that largely overlook how environmental stimuli are converted into amodal representations and how perceptions reactivate these representations and translate them back into subjective modal experiences. Developed more recently, grounded cognition theories propose that physical experiences and conceptual knowledge rely, at least in part, on the same brain regions. Thus, conceptual knowledge is hypothesized to be experienced through the reactivation of the same brain regions that are activated during physical experiences with the environment. Furthermore, if these grounded hypotheses are correct, researchers should be able to observe predictable influences of grounded information on brain activity as well as participant response latencies and accuracy in experimental conditions. To this end, three experiments were conducted testing these hypotheses using semantic categorization tasks while simultaneous recordings were taken using functional near infrared spectroscopy (NIRS) and electroencephalography. It was hypothesized that the influence of automatically reactivated grounded information would be facilitatory (i.e., resulting in faster and more accurate responses for semantically richer words) when it was task congruent, but would be inhibitory (i.e., resulting in slower and less accurate responses for semantically richer words) when it was task incongruent, thus illustrating the automatic simulation of grounded information in the processing and retrieval of conceptual knowledge. NIRS was employed to monitor event-related patterns of prefrontal cortex (PFC) hemodynamics associated with these tasks. It was hypothesized that trials with high levels of task-relevant semantic information would be discernably different than those with low levels or those trials high in task-incongruent information. That is, given the high levels of task-relevant semantic information, these trials should be comparatively easier, thus requiring less activity in the PFC, resulting in less pronounced hemodynamic responses. Electroencephalography was employed to monitor the full-scalp event-related patterns of brain activity associated with the experimental tasks. It was hypothesized that event-related potential deflections and scalp topography would be able to discern qualitatively and quantitatively different patterns of activity as a function of the amount and relevance of grounded information obtained through physical and emotional experiences with the word stimuli’s referents. The behavioural, accuracy, and electroencephalography data generally support these hypotheses. When a stimulus’s grounded information is high and task relevant, participants responded more quickly and accurately, and had discernably different patterns of brain activity than when a stimulus’s grounded information was low and task relevant. When a stimulus’s grounded information was high and task-irrelevant, participants were slower and less accurate, and exhibited patterns of brain activity that reflected both the additional semantic information and the additional processing necessary to reconcile the task incongruence. Unfortunately, data obtained from NIRS failed to illustrate meaningful condition differences. Possible reasons for this are discussed in detail in Chapter 3. Collectively, the data presented in this dissertation serve to advance and extend the claims made by grounded cognition theorists by illustrating the automatic simulation of information obtained through interactions with the environment. Further research is required to extend this work to other brain regions and to develop NIRS methods that can address these research questions

Diffusion tensor imaging and resting state functional connectivity as advanced imaging biomarkers of outcome in infants with hypoxic-ischaemic encephalopathy treated with hypothermia

Therapeutic hypothermia confers significant benefit in term neonates with hypoxic-ischaemic encephalopathy (HIE). However, despite the treatment nearly half of the infants develop an unfavourable outcome. Intensive bench-based and early phase clinical research is focused on identifying treatments that augment hypothermic neuroprotection. Qualified biomarkers are required to test these promising therapies efficiently. This thesis aims to assess advanced magnetic resonance imaging (MRI) techniques, including diffusion tensor imaging (DTI) and resting state functional MRI (fMRI) as imaging biomarkers of outcome in infants with HIE who underwent hypothermic neuroprotection. FA values in the white matter (WM), obtained in the neonatal period and assessed by tract-based spatial statistics (TBSS), correlated with subsequent developmental quotient (DQ). However, TBSS is not suitable to study grey matter (GM), which is the primary site of injury following an acute hypoxic-ischaemic event. Therefore, a neonatal atlas-based automated tissue labelling approach was applied to segment central and cortical grey and whole brain WM. Mean diffusivity (MD) in GM structures, obtained in the neonatal period correlated with subsequent DQ. Although the central GM is the primary site of injury on conventional MRI following HIE; FA within WM tissue labels also correlated to neurodevelopmental performance scores. As DTI does not provide information on functional consequences of brain injury functional sequel of HIE was studied with resting state fMRI. Diminished functional connectivity was demonstrated in infants who suffered HIE, which associated with an unfavourable outcome. The results of this thesis suggest that MD in GM tissue labels and FA either determined within WM tissue labels or analysed with TBSS correlate to subsequent neurodevelopmental performance scores in infants who suffered HIE treated with hypothermia and may be applied as imaging biomarkers of outcome in this population. Although functional connectivity was diminished in infants with HIE, resting state fMRI needs further study to assess its utility as an imaging biomarker following a hypoxic-ischaemic brain injury.Open Acces

Practice-induced functional plasticity in inhibitory control interacts with aging.

Inhibitory control deficits represent a key aspect of the cognitive declines associated with aging. Practicing inhibitory control has thus been advanced as a potential approach to compensate for age-induced neurocognitive impairments. Yet, the functional brain changes associated with practicing inhibitory control tasks in older adults and whether they differ from those observed in young populations remains unresolved. We compared electrical neuroimaging analyses of ERPs recorded during a Go/NoGo practice session with a Group (Young; Older adults) by Session (Beginning; End of the practice) design to identify whether the practice of an inhibition task in older adults reinforces already implemented compensatory activity or reduce it by enhancing the functioning of the brain networks primarily involved in the tasks. We observed an equivalent small effect of practice on performance in the two age-groups. The topographic ERP analyses and source estimations revealed qualitatively different effects of the practice over the N2 and P3 ERP components, respectively driven by a decrease in supplementary motor area activity and an increase in left ventrolateral prefrontal activity in the older but not in the young adults with practice. Our results thus indicate that inhibition task practice in older adults increases age-related divergences in the underlying functional processes

Social and Affective Neuroscience of Everyday Human Interaction

This Open Access book presents the current state of the art knowledge on social and affective neuroscience based on empirical findings. This volume is divided into several sections first guiding the reader through important theoretical topics within affective neuroscience, social neuroscience and moral emotions, and clinical neuroscience. Each chapter addresses everyday social interactions and various aspects of social interactions from a different angle taking the reader on a diverse journey. The last section of the book is of methodological nature. Basic information is presented for the reader to learn about common methodologies used in neuroscience alongside advanced input to deepen the understanding and usability of these methods in social and affective neuroscience for more experienced readers

Psychiatric Disorders

A psychiatric disorder is defined as any complex condition that involves the impairment of cognitive, emotional, or behavioral functioning. Aside from knowing the physical organic factors, its causal pathology has remained a mystery. Regarding recent advances in psychiatry and neurosciences, psychiatric disorders have been closely associated with socio-cultural, psychological, biochemical, epigenetic or neural-networking factors. A need for diverse approaches or support strategies is present, which should serve as common knowledge, empathetic views or useful skills for specialists in the filed. This book contains multifarious and powerful papers from all over the world, addressing themes such as the neurosciences, psychosocial interventions, medical factors, possible vulnerability and traumatic events. Doubtlessly, this book will be fruitful for future development and collaboration in "world psychiatry"

Wright State University\u27s Celebration of Research, Scholarship, and Creative Activities Book of Abstracts from Friday, April 11, 2014

The student abstract booklet is a compilation of abstracts from students\u27 oral and poster presentations at Wright State University\u27s second annual Celebration of Research, Scholarship and Creative Activities on April 11, 2014.https://corescholar.libraries.wright.edu/urop_celebration/1007/thumbnail.jp