Decreased Information Processing Research Articles

Alterations in functional connectivity of interoceptive and Cortico-Subcortical areas in Multiple Sclerosis-Related fatigue.

Fatigue in people with Multiple Sclerosis (PwMS) is a poorly understood, complex, and disabling symptom. We hypothesized that the perception of fatigue in PwMS results from increased information processing in cortical areas responsible for the perception of bodily states and decreased information processing in the cortico-basal ganglia network involved in the perception of motor performance. We investigated whether PwMS who perceive excessive fatigue would have increased resting-state functional connectivity (rsFC) between interoceptive brain areas (amygdala, anterior cingulate cortex [ACC], and insula) and decreased rsFC between cortico-basal ganglia premotor network compared to PwMS not reporting fatigue. Twenty-three relapsing-remitting PwMS were divided into fatigued versus non-fatigued groups based on the Modified Fatigue Impact Scale score (≥38 points). Age-matched healthy controls (n = 21) were also analyzed. All the participants underwent resting-state functional magnetic resonance imaging. PwMS who perceived abnormal fatigue, compared to non-fatigued PwMS, showed reduced rsFC between cortico-basal ganglia network and increased rsFC within interoceptive brain areas (amygdala, ACC, and insula) involved in perception of bodily states (P ≤ 0.01). Increased rsFC within interoceptive brain areas was specific for fatigued PwMS as this result did not appear when comparing PwMS (fatigued and non-fatigued) with healthy controls. The Modified Fatigue Impact Scale scores were correlated with the increased rsFC between interoceptive brain areas (amygdala and insula) and decreased rsFC between cortico-basal ganglia (P < 0.01). MS-related perceived fatigue has a central cause, and it may be due to increased interoceptive brain activity (perception of bodily states). Interventions are needed to decrease fatigue and reorganize the brain circuitry.

Spinal cord and brain atrophy patterns in neuromyelitis optica spectrum disorder and multiple sclerosis.

Spinal cord and brain atrophy are common in neuromyelitis optica spectrum disorder (NMOSD) and relapsing-remitting multiple sclerosis (RRMS) but harbor distinct patterns accounting for disability and cognitive impairment. This study included 209 NMOSD and 304 RRMS patients and 436 healthy controls. Non-negative matrix factorization was used to parse differences in spinal cord and brain atrophy at subject level into distinct patterns based on structural MRI. The weights of patterns were obtained using a linear regression model and associated with Expanded Disability Status Scale (EDSS) and cognitive scores. Additionally, patients were divided into cognitive impairment (CI) and cognitive preservation (CP) groups. Three patterns were observed in NMOSD: (1) Spinal Cord-Deep Grey Matter (SC-DGM) pattern was associated with high EDSS scores and decline of visuospatial memory function; (2) Frontal-Temporal pattern was associated with decline of language learning function; and (3) Cerebellum-Brainstem pattern had no observed association. Patients with CI had higher weights of SC-DGM pattern than CP group. Three patterns were observed in RRMS: (1) DGM pattern was associated with high EDSS scores, decreased information processing speed, and decreased language learning and visuospatial memory functions; (2) Frontal-Temporal pattern was associated with overall cognitive decline; and (3) Occipital pattern had no observed association. Patients with CI trended to have higher weights of DGM and Frontal-Temporal patterns than CP group. This study estimated the heterogeneity of spinal cord and brain atrophy patterns in NMOSD and RRMS patients at individual level, and evaluated the clinical relevance of these patterns, which may contribute to stratifying participants for targeted therapy.

Backwards walking speed reserve in persons with multiple sclerosis

BackgroundDecreased gait speed is common in persons with Multiple Sclerosis (PwMS) and has been associated with elevated fall risk. The walking speed reserve (WSR) indicates the ability to increase gait speed on demand and has previously been examined in PwMS. Backward walking is a sensitive measure of fall risk in PwMS; however, no studies have reported on the utility of backward walking speed reserve (BW-WSR) as a clinical assessment tool of functional mobility or fall risk in PwMS, nor have they associated this measure with cognition. Methods23 PwMS completed walking trials at their preferred walking speed (PWS) and maximal walking speed (MWS). Participants performed these walking trials in both the forward (FW) and backward direction (BW). The forward walking speed reserve (FW-WSR) was calculated as the difference between MWS and PWS in the forward direction, while the backward walking speed reserve (BW-WSR) was calculated as the difference between MWS and PWS in the back backward direction. Correlation analyses examined the relationship between the FW- and BW-WSR with clinical assessments of functional mobility (the timed up-and-go) as well as cognitive functioning (the Symbol Digit Modalities Test, the Brief Visuospatial Memory Test-Revised, the California Verbal Learning Test, and the Trail Making Test A and B). Correlations also examined the relationship between FW- and BW-WSR with prospective falls. ResultsA lower BW-WSR was associated with disease severity and poorer performance on clinical walking and balance assessment, as well as with decreased information processing speed and attentional performance. Interestingly, FW-WSR showed similar relations. Neither FW- or BW-WSR were associated with prospective risk in this small sample of PwMS. ConclusionThe BW-WSR did not offer a distinct advantage over other measures, such as the FW-WSR, PWS, or MWS, in the forward or backward direction. The selection of the most sensitive clinical measures of functional mobility and fall risk is crucial; our study holds valuable clinical implications for PwMS by providing novel insights into functional mobility assessments in PwMS.

Disfungsi Kognitif Post Operatif pada Geriatri

Postoperative Cognitive Dysfunction (POCD) is a neurocognitive disorder characterized by decreased cognitive performance after surgery and anesthesia. POCD is a complication characterized by memory impairment, decreased information processing and reduced attention, accompanied by changes in mood and personality. The incidence of POCD in elderly patients (&gt; 60 years) was approximately 25.8% within seven days after surgery and 10% within three months after surgery. The risk factors and etiology that lead to POCD can be reduced by good patient education, patient care and proper sanitation can prevent the tendency of POCD symptoms in these patients. Examination can be done with the learning test, the word learning test, the tracing test, the manual dexterity test, the ability test to remember a sequence of numbers. Mini Mental Status Examination (MMSE) as a screening test for dementia. MMSE is sometimes used to measure POCD. MMSE can be used in routine clinical practice to identify preoperative subclinical dementia that would put patients at a higher risk of developing POCD. Management in POCD includes two approaches, namely rapid diagnosis and prevention of POCD symptoms. Prevention by knowing the risk factors preoperative, intraoperative and postoperative. In patients with persistent POCD, it has a negative impact on quality of life, subjective memory performance, emotional symptoms, and possible health consequences such as dementia and premature death.

The Impact of Sleep Deprivation on Work Performance towards Night-shift Healthcare Workers: An Evidence-based Case Report

Background. Poor sleep and excessive fatigue among workers can reduce well-being and physical fitness. However, not many studies have mentioned how sleeping deprivation among night-shift healthcare workers impacted their work performance in multiple aspects.&#x0D; Method. We conducted an evidence-based case report (EBCR) of a night shift nurse who was worried about the impact of her sleep deprivation on her work performance in the future due to prior history of needle-stick injuries. We aimed to determine whether sleeping deprivation caused by regular night shifts leads to decreased work performance among night-shift healthcare workers by formulating a clinical question. Evidence was searched systematically using five major journal databases (Proquest, EBSCO-Host, PubMed, ScienceDirect, and Cochrane) and was assessed thoroughly using inclusion and exclusion criteria.&#x0D; Results. Eleven eligible studies were obtained with a medium level of evidence (III-IV), three systematic reviews with meta-analyses (SR-MA), three SR without MA, and five observational studies. All of them were analyzed and critically appraised using Oxford Evidence-Based Medicine and Joanna Briggs Institute tools. We found that reduced quantity and quality of sleep impacted all dimensions of work performance among healthcare professionals, be it in task performance (e.g., skill proficiency), contextual performance (e.g., communication skill and mental health issues), and patient and health worker safety (accident and medication error). It could also encourage counterproductive work behavior, such as absenteeism. Furthermore, sleep deprivation changes circadian rhythms, causing decreased information processing and affective recognition functions in some vital brain areas, ultimately affecting several work dimensions.&#x0D; Conclusion. In conclusion, stakeholders need to adjust proper shift scheduling for health care workers, practice sleep hygiene, maintain physical fitness, and consume nutritional food, positively correlated to health and productivity.

The impact of XBRL adoption on local bias: Evidence from mandated U.S. filers

This paper investigates how eXtensible Business Reporting Language (XBRL) adoption affects the information advantage of local investors relative to their non-local counterparts. By employing the recent staggered SEC mandates of XBRL as a natural shock, we show that institutional investors’ local bias decreases after firms adopt XBRL when preparing their financial statements. These results hold in a difference-in-difference research design with firm and year fixed effects or using matched nonadopting firms as controls, as well as a regression discontinuity design. The impact of XBRL adoption on reducing local bias can be explained by three economic channels: decreased information processing costs, increased corporate disclosures, and improved analyst coverage. We further find that institutions’ superior stock returns in geographic proximate equity investments significantly reduces after the XBRL mandate. The observed reduction in institutional investors’ local bias within U.S. companies following the XBRL mandate also applies to the international setting. Overall, our findings support regulators’ claim that XBRL adoption levels the playing field between local and non-local investors.

Decreased information processing speed and decision-making performance in alcohol use disorder: combined neurostructural evidence from VBM and TBSS.

Alcohol Use Disorder (AUD) is a chronic relapsing condition characterized by excessive alcohol consumption despite its multifaceted adverse consequences, associated with impaired performance in several cognitive domains including decision-making. While choice deficits represent a core component of addictive behavior, possibly consecutive to brain changes preceding the onset of the addiction cycle, the evidence on grey-matter and white-matter damage underlying abnormal choices in AUD is still limited. To fill this gap, we assessed the neurostructural bases of decision-making performance in 22 early-abstinent alcoholic patients and 18 controls, by coupling the Cambridge Gambling Task(CGT) with quantitative magnetic resonance imaging metrics of grey-matter density and white-matter integrity. Regardless of group, voxel based morphometry highlighted an inverse relationship between deliberation time and grey-matter density, with alcoholics displaying slower choices related to grey-matter atrophy in key nodes of the motor control network. In particular, grey-matter density in the supplementary motor area, reduced in alcoholic patients, explained a significant amount of variability in their increased deliberation time. Tract-based spatial statistics revealed a significant relationship betweenCGT deliberation time and all white-matter indices, involving the most relevant commissural, projection and associative tracts. The lack of choice impairments other than increased deliberation time highlights reduced processing speed, mediated both by grey-matter and white-matter alterations, as a possible marker of a generalized executive impairment extending to the output stages of decision-making. These results pave the way to further studies aiming to tailor novel rehabilitation strategies and assess their functional outcomes.

Beneficial Effect of Exercise on Cognitive Function during Peripheral Arterial Disease: Potential Involvement of Myokines and Microglial Anti-Inflammatory Phenotype Enhancement.

Peripheral arterial disease (PAD), leading to intermittent claudication, critical ischemia with rest pain, and/or tissue damage, is a public health issue associated with significant morbidity and mortality. Little is known about the link between PAD, cognitive function, and whether exercise might reduce cognitive dysfunction in PAD patients, as previously observed concerning both quality of life and prognosis. This review highlights the fact that patients suffering from PAD often demonstrate cognitive dysfunction characterized by reduced performance in nonverbal reasoning, reduced verbal fluency, and decreased information processing speed and a greater risk for progression toward dementia. Further, the data presented support that physical exercise, likely through myokine secretion and microglial anti-inflammatory phenotype enhancement, might participate in the cognition protection in common clinical settings.

Aberrant functional connectivity density in patients with treatment-refractory obsessive-compulsive disorder: a pilot study.

ObjectiveFunctional connectivity (FC) is altered in patients with obsessive-compulsive disorder (OCD). Most previous studies have focused on the strength of FC in patients with OCD; few have examined the number of functional connections in these patients. The number of functional connections is an important index for assessing aberrant FC. In the present study, we used FC density (FCD) mapping to explore alterations in the number of functional connections in patients with treatment-refractory OCD (TROCD) using the FCD index.MethodsTwenty patients with TROCD and 20 patients with OCD in clinical remission were enrolled in the study. Global FCD (gFCD) was adopted to compare the differences between the two groups of patients.ResultsThe gFCD in the left middle temporal gyrus was lower in the patients with TROCD than in those with remitted OCD, suggesting that decreased information processing ability may play a significant role in TROCD.ConclusionThe left middle temporal gyrus is a key component of the emotional processing circuit and attentional processing circuit. Decreased information processing ability in this brain region may play a significant role in TROCD; however, further well-designed follow-up studies are needed to support this hypothesis.

Digging deeper in the differential effects of inflammatory and psychosocial stressors in remitted depression: Effects on cognitive functioning

BackgroundMajor Depressive Disorder (MDD) covers a wide spectrum of symptoms, including cognitive dysfunction, which can persist during remission. Both inflammatory states and psychosocial stress play a role in MDD pathogenesis. MethodsThe effects of inflammatory (i.e., Salmonella typhi vaccine) and psychosocial stressor (i.e., Trier Social Stress Test), as well as their combination were investigated on cognition in women (aged 25–45 years, n = 21) with (partially) remitted MDD and healthy controls (n = 18) in a single-blind placebo-controlled study. In a crossover design, patients received on the first day one of the aforementioned interventions and on the other day a placebo, or vice versa, with a washout period of 7–14 days. Short-term and verbal memory, working memory, attention, verbal fluency, information processing speed, psychomotor function, and measures of attentional bias to emotions were measured. Exploratory analyses were performed to assess the correlation between biomarkers of inflammation and the Hypothalamic–Pituitary–Adrenal axis and cognitive functioning. ResultsIn patients, inflammatory stress decreased information processing speed and verbal memory, and increased working memory; after psychosocial stress, there was an increase in attention. There was also an increased negative attentional bias in patients after inflammatory stress. Neither stressor had any effect in controls. LimitiationsLimitations are the relatively small sample size and antidepressant use by a part of the participants. The effects of the stressors were also measured a relatively short period after administration. ConculsionPatients were sensitive to the cognitive effects of inflammation and psychosocial stress on cognition, while controls were not.

Altered White Matter Integrity in Human Immunodeficiency Virus-Associated Neurocognitive Disorder: A Tract-Based Spatial Statistics Study.

ObjectiveHuman immunodeficiency virus (HIV) infection has been known to damage the microstructural integrity of white matter (WM). However, only a few studies have assessed the brain regions in HIV-associated neurocognitive disorders (HAND) with diffusion tensor imaging (DTI). Therefore, we sought to compare the DTI data between HIV patients with and without HAND using tract-based spatial statistics (TBSS).Materials and MethodsTwenty-two HIV-infected patients (10 with HAND and 12 without HAND) and 11 healthy controls (HC) were enrolled in this study. A whole-brain analysis of fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity was performed with TBSS and a subsequent 20 tract-specific region-of-interest (ROI)-based analysis to localize and compare altered WM integrity in all group contrasts.ResultsCompared with HC, patients with HAND showed decreased FA in the right frontoparietal WM including the upper corticospinal tract (CST) and increased MD and RD in the bilateral frontoparietal WM, corpus callosum, bilateral CSTs and bilateral cerebellar peduncles. The DTI values did not significantly differ between HIV patients with and without HAND or between HIV patients without HAND and HC. In the ROI-based analysis, decreased FA was observed in the right superior longitudinal fasciculus and was significantly correlated with decreased information processing speed, memory, executive function, and fine motor function in HIV patients.ConclusionThese results suggest that altered integrity of the frontoparietal WM contributes to cognitive dysfunction in HIV patients.

Procedural Variations in the Stroop and the Symbol Digit Modalities Test: Impact on Patients with Multiple Sclerosis

Decreased information processing speed is often cited as the primary cognitive deficit occurring in conjunction with multiple sclerosis (MS). Two common tools for assessing this deficit are the Stroop Test and the Symbol Digit Modalities Test (SDMT). However, there are procedural variations in these rapid serial processing (RSP) tests pertaining to the response format (e.g., verbal or manual) and the administration format (e.g., paper-based or computerized). The present study was designed to assess whether such variations impact MS patients' and healthy individuals' performance on these tests. In Experiment 1, we showed that response formats in which either the experimenter or the participant was responsible for advancing the items on computerized versions of the Stroop Test and the SDMT were basically equivalent in terms of distinguishing between patients and controls. In Experiment 2, we found differences between administration formats that appear to interact with some of the disease-related features of MS. Understanding how procedural variations differentially impact patients and controls can be useful for interpreting what RSP tests reveal about the cognitive impact of MS.

Neuropsychological, medical and rehabilitative management of persons with multiple sclerosis

Multiple sclerosis (MS) is a chronic and disabling disease that attacks the central nervous system (CNS). The symptoms, progression, and severity of the disease are unpredictable and vary from one person to another. Major symptoms include fatigue, sensory-motor (e.g., visual disturbance, spasticity, locomotion), cognitive (e.g., decreased information processing speed, impaired memory), and psychiatric problems (e.g., depression). Although the etiology is unknown, MS is thought to be an autoimmune disease triggered by a viral or other infectious agent in genetically susceptible individuals. The CNS target of the disease is myelin, although it is now known that other aspects of the CNS such as axonal and gray matter regions are also involved.

Cognitive Function, Depression, Fatigue, and Activities of Daily Living in Patients With Neuromyelitis Optica After Acute Relapse

ABSTRACTThe status of fatigue, depression, and activities of daily living and their relationships with cognitive function in patients with neuromyelitis optica (NMO) after acute relapse has never been observed. This study investigated cognitive function, fatigue, depression, activities of daily living, and the relationships among them in NMO patients. Twenty-two NMO patients without visible lesions on conventional brain MRI after acute relapse, 22 depression patients, and 22 healthy comparison subjects received several scales to assess cognitive function, fatigue, and depression. Every NMO patient completed a survey of activities of daily living. Between-group comparisons and correlational analyses were applied to examine the differences and the relationships among them. We found that NMO patients had significantly impaired memory, decreased information processing speed, and damaged attention. Some impaired cognitive domains were significantly correlated with fatigue and depression, and activities of daily living were correlated with these impaired cognitive domains, fatigue, depression, and disability. These results confirm cognitive deficits in memory, information processing speed, and attention exist in NMO patients without visible brain lesions after acute relapse. Fatigue and depression may affect cognitive function and increase the negative impact of cognitive deficits on the activities of daily living in patients with NMO.

Cognitive impairment and whole brain diffusion in patients with neuromyelitis optica after acute relapse

The objective of this study investigated cognitive impairments and their correlations with fractional anisotropy (FA) and mean diffusivity (MD) in patients with neuromyelitis optica (NMO) without visible lesions on conventional brain MRI during acute relapse. Twenty one patients with NMO and 21 normal control subjects received several cognitive tests to assess cognitive function. Head diffusion tensor imaging (DTI) of all patients with NMO were collected with a 3-T MR system. Correlations of cognitive test scores and whole brain FA and MD were examined by voxel-based analysis. Region-of-interest analysis was applied to the significantly correlated regions which the most frequently appeared. We found that NMO patients without visible brain lesions had significantly impaired learning and memory, decreased information processing speed, and damaged attention compared with normal control subjects. These impaired cognitive domains were significantly correlated with FA and MD in local regions of corpus callosum, anterior cingulate and medial frontal cortex. In corpus callosum of NMO patients, mean FA was significantly lower and mean MD higher than normal control subjects. Our findings suggest that cognitive impairments in learning and memory, information processing speed and attention occur in NMO patients without visible brain lesions during acute relapse. The impairments in immediate and short-term memory in NMO patients may be due to information encoding deficits in the process of information acquisition. The corpus callosum of such patients may have local microscopic damages that play a role in cognitive impairments during acute relapse.

Mental fatigue and impaired information processing after mild and moderate traumatic brain injury

Primary objective: Mental fatigue is a common symptom after brain injury. Its mechanisms are not fully understood and it has been difficult to find an objective way of measuring it. The aim was to compare cognitive tests with a new self-assessment questionnaire about mental fatigue.Methods and procedures: Individuals reporting mental fatigue for 6 months or more after mild traumatic brain injury (MTBI) or traumatic brain injury (TBI) and controls were assessed for subjective fatigue, information processing speed, working memory and attention. Depression and anxiety were also assessed in the individuals with brain injury.Results: Individuals with MTBI or TBI reported significantly more problems with mental fatigue and related symptoms than controls. A significantly decreased information processing speed (digit symbol-coding, reading speed, trail making test) was found in those on sick leave due to MTBI or TBI, compared to controls. Divided attention was affected to a lesser extent and no effect was detected on working memory.Conclusion: Mental fatigue after MTBI can last for several years. It can be profoundly disabling and affect working capacity as well as social activities. Subjective mental fatigue following brain injury is suggested to mainly correlate with objectively measured information processing speed.

Progression of Cerebral Small Vessel Disease in Relation to Risk Factors and Cognitive Consequences

Cerebral white matter lesions and lacunar infarcts are small vessel disease-related lesions, which are associated with cognitive decline and dementia. We aimed to assess the relationship between risk factors, effect modifiers, and progression of these lesions. Furthermore, we studied the cognitive consequences of lesion progression. Six hundred sixty-eight people, aged 60 to 90 years, underwent repeated MRI scanning and neuropsychological testing within 3-year follow-up. We rated incident lacunar infarcts and change in periventricular and subcortical white matter lesion severity with a semiquantitative scale. We assessed the relationships between age, sex, baseline lesion load, risk factors, lesion progression, and change in cognitive function by multivariate regression analyses and additional stratified analyses. Baseline lesion load, higher age, high blood pressure, and current smoking were independently associated with progression of white matter lesions. Women had more marked progression of subcortical white matter lesions and incident lacunar infarcts compared with men. Carotid atherosclerosis was associated with incident lacunar infarcts. Higher blood pressure did not contribute to lesion progression in people with already severe lesions at baseline nor in the very old. Lesion progression was associated with a paralleled decline in general cognitive function and in particular with a decreased information processing speed. Higher age, female sex, cigarette smoking, elevated blood pressure, and baseline lesion load were associated with small vessel disease progression. Age and baseline lesion load influenced the risk relations with blood pressure. Progression of small vessel disease was related to a paralleled decline in cognitive function.

RCBF pathology in Alzheimer's disease is associated with slow processing speed

Decreased information processing speed (mental slowing) is a known sequelae of many brain disorders, and can be assessed by continuous naming tasks. Functional imaging studies have shown that pause and articulation times in continuous speech are normally associated with different brain regions, but knowledge about such association in dementia is lacking. We therefore tested the hypothesis that perfusion deficits in Alzheimer's disease (AD) are not only associated with slower processing, but also with these speech measures. Using regional cerebral blood flow (rCBF) measurements during the performance of a continuous colour and form-naming task, we found that naming speed was substantially slower in AD patients than in controls. This slower naming was exclusively determined by an increase in mean pause time, and only to a limited extent by articulation time. The increased pause time was uniquely associated with temporo-parietal rCBF reductions of the patients, while articulation was not. By contrast, the rCBF of healthy elderly control subjects was consistently accompanied by substantially shorter articulation and pause times, although the naming measures were not statistically associated with rCBF.These findings suggest that pause time (in contrast to articulation time) may serve as a sensitive measure in the assessment of information processing speed deficits in dementia, by virtue of its close association with brain pathology.

Do Managers and Strategies Matter? A Study In Crisis*

ABSTRACTHighly interactive, tightly coupled, high‐risk technological systems have introduced the potential for catastrophic events. Although many people consider crises and disasters to be inevitable, our results suggest that firms that are better able to avoid crisis events have top‐management teams with a higher level of functional team heterogeneity, higher education levels, shorter organizational tenures, and more tenure heterogeneity. These characteristics serve as proxies for deeper underlying cognitive processes such as more complex thinking, quality decision making, dialectical inquiry, and multiple perspectives in solving potential catastrophic problems. These cognitive and social processes appear to be successful in addressing interactive complexity in high‐risk technologies, and may be associated with fewer faulty assumptions about firms' vulnerability to crises. In addition, firms whose top managers' time and energy is devoted to managing acquisition and divestment activities are more likely to experience crisis events. Highly diversified firms emphasizing financial and bureaucratic controls appear to develop threat‐rigidities, a lack of firm specific knowledge, and decreased information processing capabilities making them increasingly vulnerable to systemic crisis events.

Rethinking Mammalian Brain Evolution

A critical review of past and current theories of mammalian brain evolution is presented in order to discuss conceptual problems that persist in the field. Problems with the concept of homology arise because of the interaction of cell lineages and axonal connectivity in the determination of structural features of the brain. Focusing on the continuity of information represented by ontogenetic mechanisms as opposed to morphological features avoids many of these problems and suggests homological relationships that otherwise have gone unnoticed. Many apparently progressive trends and parallelisms in mammalian brain evolution turn out to result from the influence of underlying developmental homologies. Confusions about evolutionary advancement, increasing architectonic differentiation, and the evolution of new brain structures result from a failure to appreciate how increasing brain size can bias developmental processes with respect to axonal competition, increased cellular metabolic demands and decreased information processing efficiency. Explanations of the evolution of novel structures and new connectional patterns are criticized for their failure to consider the constraints of neural developmental processes. The correlations between structural neogenesis, functional specialization and size changes in brain evolution are explained by a theory of competitive displacement of neural connections by others during development under the biasing influences of differential allometry, cell death or axon-target affinity changes. The “displacement hypothesis” is used to propose speculative accounts for the differential enlargement and multiplication of cortical areas, the origins of mammalian isocortex, the unusual features of dolphin cortex and the dramatic structural and functional reorganizations that characterize human brain evolution.