Climate change, human health, and resilience in the Holocene.

Climate change is an indisputable threat to human health, especially for societies already confronted with rising social inequality, political and economic uncertainty, and a cascade of concurrent environmental challenges. Archaeological data about past climate and environment provide an important source of evidence about the potential challenges humans face and the long-term outcomes of alternative short-term adaptive strategies. Evidence from well-dated archaeological human skeletons and mummified remains speaks directly to patterns of human health over time through changing circumstances. Here, we describe variation in human epidemiological patterns in the context of past rapid climate change (RCC) events and other periods of past environmental change. Case studies confirm that human communities responded to environmental changes in diverse ways depending on historical, sociocultural, and biological contingencies. Certain factors, such as social inequality and disproportionate access to resources in large, complex societies may influence the probability of major sociopolitical disruptions and reorganizations-commonly known as "collapse." This survey of Holocene human-environmental relations demonstrates how flexibility, variation, and maintenance of Indigenous knowledge can be mitigating factors in the face of environmental challenges. Although contemporary climate change is more rapid and of greater magnitude than the RCC events and other environmental changes we discuss here, these lessons from the past provide clarity about potential priorities for equitable, sustainable development and the constraints of modernity we must address.

Deconstructing Poststroke Delirium in a Prospective Cohort of Patients With Intracerebral Hemorrhage.

OBJECTIVES: Poststroke delirium may be underdiagnosed due to the challenges of disentangling delirium symptoms from underlying neurologic deficits. We aimed to determine the prevalence of individual delirium features and the frequency with which they could not be assessed in patients with intracerebral hemorrhage. DESIGN: Prospective observational cohort study. SETTING: Neurocritical Care and Stroke Units at a university hospital. PATIENTS: Consecutive patients with intracerebral hemorrhage from February 2018 to May 2018. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: An attending neurointensivist performed 257 total daily assessments for delirium on 60 patients (mean age 68.0 [SD 18.4], 62% male, median intracerebral hemorrhage score 1.5 [interquartile range 1-2], delirium prevalence 57% [n = 34]). Each assessment included the Confusion Assessment Method for the ICU, Intensive Care Delirium Screening Checklist, a focused bedside cognitive examination, chart review, and nurse interview. We characterized individual symptom prevalence and established delirium diagnoses using Diagnostic and Statistical Manual of Mental Disorders, fifth edition criteria, then compared performance of the Confusion Assessment Method for the ICU and Intensive Care Delirium Screening Checklist against reference-standard expert diagnosis. Symptom fluctuation (61% of all assessments), psychomotor changes (46%), sleep-wake disturbances (46%), and impaired arousal (37%) had the highest prevalence and were never rated "unable to assess," while inattention (36%), disorientation (27%), and disorganized thinking (18%) were also common but were often rated 'unable to assess' (32%, 43%, and 44% of assessments, respectively), most frequently due to aphasia (32% of patients). Including nonverbal assessments of attention decreased the frequency of 'unable to assess' ratings to 11%. Since the Intensive Care Delirium Screening Checklist may be positive without the presence of symptoms that require verbal assessment, it was more accurate (sensitivity = 77%, specificity = 97%, area under the receiver operating characteristic curve, 0.87) than the Confusion Assessment Method for the ICU (sensitivity = 41%, specificity = 88%, area under the receiver operating characteristic curve, 0.64). CONCLUSIONS: Delirium is common after intracerebral hemorrhage, but severe neurologic deficits may confound its assessment and lead to underdiagnosis. The Intensive Care Delirium Screening Checklist's inclusion of nonverbal features may make it more accurate than the Confusion Assessment Method for the ICU in patients with neurologic deficits, but novel tools designed for such patients may be warranted.

Inflammatory periosteal reaction on ribs associated with lower respiratory tract disease: A method for recording prevalence from sites with differing preservation.

OBJECTIVES: Inflammatory periosteal reaction (IPR) on the visceral surfaces of the ribs has been used in bioarchaeology as an indicator of lower respiratory tract disease. This article presents a detailed method for recording IPR on the ribs, even those in severely fragmented states, with the objectives of increasing the consistency of recording and producing true prevalence rates for skeletons so as to improve data comparability between future bioarchaeological studies of lower respiratory tract disease. MATERIALS AND METHODS: The presence and prevalence of respiratory-related IPR were recorded from three different Sudanese cemetery sites using a detailed method for identifying and recording IPR. Sites with variable preservation were chosen to test the applicability of the method. A flowchart to aid in identification of bony changes is presented. The method requires the recording of IPR on three separate sections of the rib (neck, angle, and shaft) and the allocation of ribs into rib cage regions of upper, upper-middle, middle, lower-middle, and lower. RESULTS: Results demonstrate differences in the distribution of IPR between sites and verify the method's applicability to archeological sites with various levels of skeletal preservation. DISCUSSION: While crude prevalence rates can indicate the number of individuals experiencing lower respiratory tract disease within a site, this method can provide information about the distribution of IPR within the rib cage. This should lead to new ways of distinguishing respiratory diseases within archeological populations. This method also allows for comparability between well-preserved and lesser-preserved sites by accommodating for rib fragmentation.

Left-sided brain injury associated with more hospital-acquired infections during inpatient rehabilitation.

OBJECTIVE: To test the hypothesis that a left-dominant brain immune network (LD-BIN) might affect the occurrence of infection during inpatient rehabilitation of stroke and traumatic brain injury (TBI). DESIGN: A retrospective analysis was performed on electronic medical records between January 2009 and December 2010. All patients with left- or right-sided stroke or TBI were included into the study. The LD-BIN hypothesis was tested by comparing HAI rates depending on whether patients had left- or right-sided brain lesions. SETTING: A large inpatient rehabilitation hospital. PARTICIPANTS: Among the patients (N=2236) with stroke or TBI who had either a left- or right-sided brain lesion, 163 patients were identified with HAIs. INTERVENTION: Not applicable. MAIN OUTCOME MEASURE: Frequency of HAIs. RESULTS: In the 163 patients identified with HAIs with a diagnosis of stroke or TBI, chi-square analysis revealed a significantly higher proportion of HAIs among patients with left-sided (n=98; 60.1%) relative to right-sided (n=65; 39.9%) brain injuries (χ(2)=6.68, P<.01). These effects could not be attributed to either clinical or demographic factors. CONCLUSIONS: Our findings are consistent with the hypothesis that an LD-BIN may mediate vulnerability to infection during rehabilitation of patients with stroke or TBI. Further translational research investigating novel means of managing patients based on brain lesion location, and modulating the LD-BIN via behavioral and physiologic interventions, may result in neuroscience-based methods to improve infection resistance in brain-injured patients.

Examination of human osteoarchaeological remains as a feasible source of polar and apolar metabolites to study past conditions.

Metabolomics is a modern tool that aids in our understanding of the molecular changes in organisms. Archaeological science is a branch of archaeology that explores different archaeological materials using modern analytical tools. Human osteoarchaeological material are a frequent finding in archaeological contexts and have the potential to offer information about previous human populations, which can be illuminating about our current condition. Using a set of samples comprising different skeletal elements and bone structures, here we explore for the first time the possibility of extracting metabolites from osteoarchaeological material. Here, a protocol for extraction and measurement of extracted polar and less-polar/apolar metabolites by ultra-high performance liquid chromatography hyphenated to high resolution mass spectrometry is presented to measure the molecules separated after a reversed phase and hydrophilic interaction liquid chromatography column. Molecular information was obtained, showing that osteoarchaeological material is a viable source of molecular information for metabolomic studies.

Psychometric evaluation of neglect assessment reveals motor-exploratory predictor of functional disability in acute-stage spatial neglect.

OBJECTIVE: To determine the psychometric properties of 2 neglect measures, the Behavioral Inattention Test (BIT)-conventional and the Catherine Bergego Scale (CBS), in acute spatial neglect. Spatial neglect is a failure or slowness to respond, orient, or initiate action toward contralesional stimuli, associated with functional disability that impedes stroke recovery. Early identification of specific neglect deficits may identify patients likely to experience chronic disability. However, psychometric evaluation of assessments has focused on subacute/chronic populations. DESIGN: Correlational/psychometric study. SETTING: Inpatient rehabilitation hospital. PARTICIPANTS: Screening identified 51 consecutive patients with a right-hemisphere stroke with left neglect (BIT score <129 or CBS score >11) tested an average of 22.3 days poststroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We obtained BIT, CBS, and Barthel Index assessments for each participant and clinical and laboratory measures of perceptual-attentional and motor-intentional deficits. RESULTS: The BIT showed good reliability and loaded onto a single factor. Consistent with our theoretical prediction, principal components analysis of the CBS identified 2 underlying factors: Where perceptual-attentional items (CBS-PA) and embodied, motor-exploratory items (CBS-ME). The CBS-ME uniquely predicted deficits in activities of daily living (ADLs) assessed by using the Barthel Index, but did not predict clinical and laboratory assessments of motor-intentional bias. More severe neglect on the CBS-PA correlated with greater Where perceptual-attentional bias on clinical and laboratory tests, but did not uniquely predict deficits in ADLs. CONCLUSIONS: Our results indicate that assessments of spatial neglect may be used to detect specific motor-exploratory deficits in spatial neglect. Obtaining CBS-ME scores routinely might improve the detection of acute-stage patients with spatial action deficits requiring increased assistance that may persist to the chronic stage.

Functional assessment of spatial neglect: a review of the Catherine Bergego scale and an introduction of the Kessler foundation neglect assessment process.

Spatial neglect is a debilitating poststroke neurocognitive disorder associated with prolonged hospitalization and poor rehabilitation outcomes. The literature suggests a high prevalence of this disorder, but clinicians have difficulty reliably identifying affected survivors. This discrepancy may result from suboptimal use of validated neglect assessment procedures. In this article, we suggest use of a validated assessment tool that is sensitive to identification of neglect and its functional consequences - the Catherine Bergego Scale (CBS). We provide detailed item-by-item instructions for observation and scoring - the Kessler Foundation Neglect Assessment Process (KF-NAP). Rehabilitation researchers may be able to use the CBS via the KF-NAP to measure ecological outcomes and specific, separable perceptual-attentional and motor-exploratory spatial behaviors.

Consequences of stroke in community-dwelling elderly: the health and retirement study, 1998 to 2008.

BACKGROUND AND PURPOSE: Stroke survivors are at risk of developing comorbidities that further reduce their quality of life. The purpose of this study was to determine the risk of developing a secondary health problem after stroke. METHODS: We performed a case-control analysis using 6 biennial interview waves (1998 to 2008) of the Health and Retirement Study. We compared 631 noninstitutionalized individuals who had a single stroke with 631 control subjects matched for age, gender, and interview wave. We studied sleep problems, urinary incontinence, motor impairment, falls, and memory deficits among the 2 groups. RESULTS: Stroke survivors frequently developed new or worsened motor impairment (33%), sleep problems (up to 33%), falls (30%), urinary incontinence (19%), and memory deficits (9%). As compared with control subjects, the risk of developing a secondary health problem was highest for memory deficits (OR, 2.45; 95% CI, 1.34 to 4.46) followed by urinary incontinence (OR, 1.86; 95% CI, 1.31 to 2.66), motor impairment (OR, 1.61; 95% CI, 1.16 to 2.24), falls (OR, 1.5; 95% CI, 1.12 to 2.0), and sleep disturbances (OR, 1.49; 95% CI, 1.09 to 2.03). In contrast, stroke survivors were not more likely to injure themselves during a fall (OR, 1.14; 95% CI, 0.72 to 1.79). After adjusting for cardiovascular risk factors, social status, psychiatric symptoms, and pain, the risks of falling or developing sleep problems were not different from the control subjects. CONCLUSIONS: The risk of developing a secondary health problem that can impact daily life is markedly increased after stroke. A better understanding of frequencies and risks for secondary health problems after stroke is necessary for designing better preventive and rehabilitation strategies.

Spatial bias and right hemisphere function: sex-specific changes with aging.

Patterns of cerebral asymmetry related to visuospatial functions may change with age. The typical leftward bias on a line bisection task may reflect cerebral asymmetry. With age, such leftward bias decreases. This study demonstrated that the age-related decrease of leftward bias may actually be sex-specific. In addition, previous research suggests that young adults' deviation in line bisection may reflect asymmetric hemispheric activation of perceptual-attentional "where" spatial systems, rather than motor-intentional "aiming" spatial systems; thus, we specifically fractionated "where" and "aiming" bias of men and women ranging in age from 22 to 93 years old. We observed that older men produced greater rightward line bisection errors, of primarily "where" spatial character. However, women's errors remained leftward biased, and did not significantly change with age. "Where" spatial systems may be linked to cortico-cortical processing networks involving the posterior part of the dorsal visuospatial processing stream. Thus, the current results are consistent with the conclusion that reduced right dorsal spatial activity in aging may occur in the male, but not female, adult spatial system development.

Transcranial magnetic stimulation (TMS): potential progress for language improvement in aphasia.

Aphasia researchers and clinicians share some basic beliefs about language recovery post stroke. Most agree there is a spontaneous recovery period and language recovery may be enhanced by participation in a behavioral therapy program. The application of biological interventions in the form of pharmaceutical treatments or brain stimulation is less well understood in the community of people who work with individuals having aphasia. The purpose of this article is to review the literature on electrical brain stimulation as an intervention to improve aphasia recovery. The article will emphasize emerging research on the use of transcranial magnetic stimulation (TMS) to accelerate stroke recovery. We will profile the current US Food and Drug Administration (FDA)-approved application to depression to introduce its potential for future application to other syndromes such as aphasia.

Paleopathology of the Ychsma: Evidence of respiratory disease during the Late Intermediate Period (AD 1000-1476) at the Central Coastal site of Pachacamac, Peru.

OBJECTIVE: To investigate evidence for maxillary sinusitis and pulmonary inflammation in archaeological skeletons dating to the Late Intermediate Period (AD 1000-1476) at the site of Pachacamac, Peru. MATERIALS: Thirty-nine individuals (male, female, and unknown sex; 16+ years age-at-death) were analyzed for inflammatory periosteal reaction (IPR) on the visceral (inner) surfaces of the ribs, and 16 individuals were analyzed for evidence of maxillary sinusitis. METHODS: All individuals were macroscopically examined for bony changes in the maxillary sinuses and new bone formation on the ribs according to pre-established criteria. RESULTS: Some 33.3% (13/39) of individuals had IPR on the ribs and 93.8% (15/16) had bony changes in the maxillary sinuses. CONCLUSIONS: Respiratory disease was likely prevalent in people buried at Pachacamac during the Late Intermediate Period. A number of factors may have increased the risk of developing respiratory disease, including exposure to poor air quality and increased crowding and social mixing, resulting from pilgrimage to this important ritual center. SIGNIFICANCE: This paper represents one of the first systematic analyses of evidence for respiratory disease in Peruvian and South American human skeletal remains, demonstrating the suitability of the region for further study. LIMITATIONS: A limited sample was available for analysis. Additionally, the site's skeletal preservation was excellent, meaning the sample available for assessment of maxillary sinusitis was smaller, being limited to individuals with post-mortem breakage. FURTHER RESEARCH: The results of this study should stimulate further much needed systematic investigation of evidence for respiratory disease in other Peruvian and South American populations.

Time to be nosy: Evaluating the impact of environmental and sociocultural changes on maxillary sinusitis in the Middle Nile Valley (Neolithic to Medieval periods).

OBJECTIVE: To investigate the prevalence of maxillary sinusitis in people who lived in the Middle Nile Valley across different periods, cultures, and environmental conditions. MATERIALS: 481 skeletons from 13 sites, curated at the British Museum, London, were analysed. The sites ranged in date from the Neolithic to Medieval periods (c. 4900 BCE-CE 1500). METHODS: Bony changes within the maxillary sinuses, associated with sinusitis and oroantral fistulae were systematically recorded according to pre-established criteria. RESULTS: There were significant differences in the prevalence of maxillary sinusitis between time period/subsistence economy groups. The Neolithic hunter-gatherer/early agricultural group had the lowest prevalence, whilst the urban group demonstrated the highest frequency of the disease. CONCLUSIONS: Factors involved in the development of maxillary sinusitis are manifold and complex. However, the results indicate that increased aridity in Sudan in later periods and intensification of agricultural practices may have played a role in increasing prevalence of the disease. Urban environments, including crowding, poor sanitation, and industrial air pollution, could also have influenced susceptibility to maxillary sinusitis. SIGNIFICANCE: Prior to this paper, the impact of arid environments on respiratory health in the past had received little attention despite growing clinical research on the topic. Both arid and urban environments are predicted to expand in the future. This paper provides a deep-time perspective on an issue of increasing concern today. LIMITATIONS: Poor preservation of skeletons and a lack of archaeological settlement data for some sites. FUTURE RESEARCH: Investigation of a greater range of populations from different environments/climates.

Asymmetrical effects of adaptation to left- and right-shifting prisms depends on pre-existing attentional biases.

Proposals that adaptation with left-shifting prisms induces neglect-like symptoms in normal individuals rely on a dissociation between the postadaptation performance of individuals trained with left- versus right-shifting prisms (e.g., Colent, Pisella, & Rossetti, 2000). A potential problem with this evidence is that normal young adults have an a priori leftward bias (e.g., Jewell & McCourt, 2000). In Experiment 1, we compared the line bisection performance of young adults to that of aged adults, who as a group may lack a leftward bias in line bisection. Participants trained with both left- and right-shifting prisms. Consistent with our hypothesis, while young adults demonstrated aftereffects for left, but not right prisms, aged adults demonstrated reliable aftereffects for both prisms. In Experiment 2, we recruited a larger sample of young adults, some of whom were right-biased at baseline. We observed an interaction between baseline bias and prism-shift, consistent with the results of Experiment 1: Left-biased individuals showed a reduced aftereffect when training with right-shifting prisms and right-biased individuals showed a reduced aftereffect when training with left-shifting prisms. These results suggest that previous failures to find generalizable aftereffects with right-shifting prisms may be driven by participants' baseline biases rather than specific effects of the prism itself.

Vision therapy in adults with convergence insufficiency: clinical and functional magnetic resonance imaging measures.

PURPOSE: This research quantified clinical measurements and functional neural changes associated with vision therapy in subjects with convergence insufficiency (CI). METHODS: Convergence and divergence 4° step responses were compared between 13 control adult subjects with normal binocular vision and four CI adult subjects. All CI subjects participated in 18 h of vision therapy. Clinical parameters quantified throughout the therapy included: nearpoint of convergence, recovery point of convergence, positive fusional vergence at near, near dissociated phoria, and eye movements that were quantified using peak velocity. Neural correlates of the CI subjects were quantified with functional magnetic resonance imaging scans comparing random vs. predictable vergence movements using a block design before and after vision therapy. Images were quantified by measuring the spatial extent of activation and the average correlation within five regions of interests (ROI). The ROIs were the dorsolateral prefrontal cortex, a portion of the frontal lobe, part of the parietal lobe, the cerebellum, and the brain stem. All measurements were repeated 4 months to 1 year post-therapy in three of the CI subjects. RESULTS: Convergence average peak velocities to step stimuli were significantly slower (p = 0.016) in CI subjects compared with controls; however, significant differences in average peak velocities were not observed for divergence step responses (p = 0.30). The investigation of CI subjects participating in vision therapy showed that the nearpoint of convergence, recovery point of convergence, and near dissociated phoria significantly decreased. Furthermore, the positive fusional vergence, average peak velocity from 4° convergence steps, and the amount of functional activity within the frontal areas, cerebellum, and brain stem significantly increased. Several clinical and cortical parameters were significantly correlated. CONCLUSIONS: Convergence peak velocity was significantly slower in CI subjects compared with controls, which may result in asthenopic complaints reported by the CI subjects. Vision therapy was associated with and may have evoked clinical and cortical activity changes.

Postacute reevaluation may prevent Dysphagia-associated morbidity.

BACKGROUND AND PURPOSE: Accurate identification and tailored management of patients with dysphagia is necessary to prevent complications when dysphagia is present and avoid implications of dietary restriction when unnecessary. Methods of dysphagia assessment vary, and a reassessment in the postacute period is not an established standard. The aim of this retrospective study was to compare initial dysphagia assessment with dysphagia reassessment results for stroke patients admitted to our inpatient rehabilitation facility. METHODS: We examined medical records of 226 acute stroke patients admitted to our inpatient rehabilitation facility from December 2006 to May 2007. We excluded 86 subjects, then noted the presence or absence of dysphagia based on documentation and prescribed diet and management strategies in the remaining 146 records. RESULTS: Dysphagia was identified in 94 patients (64%) assessed at our facility. Of these patients, 11% (n=10) were not previously identified in acute care (nonnegligible number, P<0.0001). Agreement regarding presence or absence of dysphagia occurred in 85%. However, prescribed diet differed in 51% (n=75), with 12% (n=18) requiring diet downgrades on admission for rehabilitation. CONCLUSIONS: The necessity of dysphagia reassessment as part of routine postacute stroke rehabilitation care is not completely established. Our study supports the need for postacute reassessment as 11% of patients with dysphagia would not have been identified without reassessment and 12% required diets more conservative than prescribed in acute care. Prospective research addressing dysphagia specific outcomes is warranted to develop efficient and high-quality standards for preventing poststroke dysphagia associated morbidity.

Risk factors associated with injury attributable to falling among elderly population with history of stroke.

BACKGROUND AND PURPOSE: Stroke survivors are at high risk for falling. Identifying physical, clinical, and social factors that predispose stroke patients to falls may reduce further disability and life-threatening complications, and improve overall quality of life. METHODS: We used 5 biennial waves (1998-2006) from the Health and Retirement Study to assess risk factors associated with falling accidents and fall-related injuries among stroke survivors. We abstracted demographic data, living status, self-evaluated general health, and comorbid conditions. We analyzed the rate ratio (RR) of falling and the OR of injury within 2 follow-up years using a multivariate random effects model. RESULTS: We identified 1174 stroke survivors (mean age+/-SD, 74.4+/-7.2 years; 53% female). The 2-year risks of falling, subsequent injury, and broken hip attributable to fall were 46%, 15%, and 2.1% among the subjects, respectively. Factors associated with an increased frequency of falling were living with spouse as compared to living alone (RR, 1.4), poor general health (RR, 1.1), time from first stroke (RR, 1.2), psychiatric problems (RR, 1.7), urinary incontinence (RR, 1.4), pain (RR, 1.4), motor impairment (RR, 1.2), and past frequency of > or = 3 falls (RR, 1.3). Risk factors associated with fall-related injury were female gender (OR, 1.5), poor general health (OR, 1.2), past injury from fall (OR, 3.2), past frequency of > or = 3 falls (OR, 3.1), psychiatric problems (OR, 1.4), urinary incontinence (OR, 1.4), impaired hearing (OR, 1.6), pain (OR, 1.8), motor impairment (OR, 1.3), and presence of multiple strokes (OR, 3.2). CONCLUSIONS: This study demonstrates the high prevalence of falls and fall-related injuries in stroke survivors, and identifies factors that increase the risk. Modifying these factors may prevent falls, which could lead to improved quality of life and less caregiver burden and cost in this population.

Monocular patching may induce ipsilateral "where" spatial bias.

Spatial bias is an asymmetry of perception and/or representation of spatial information - "where" bias -, or of spatially directed actions - "aiming" bias. A monocular patch may induce contralateral "where" spatial bias (the Sprague effect [Sprague, J. M. (1966). Interaction of cortex and superior colliculus in mediation of visually guided behavior in cat. Science, 153(3743), 1544-1547]). However, an ipsilateral patch-induced spatial bias may be observed if visual occlusion results in top-down, compensatory re-allocation of spatial perceptual or representational resources toward the region of visual deprivation. Tactile distraction from a monocular patch may also contribute to an ipsilateral bias. To examine these hypotheses, neurologically normal adults bisected horizontal lines at baseline without a patch, while wearing a monocular patch, and while wearing tactile-only and visual-only monocular occlusion. We fractionated "where" and "aiming" spatial bias components using a video apparatus to reverse visual feedback for half of the test trials. The results support monocular patch-induced ipsilateral "where" spatial errors, which are not consistent with the Sprague effect. Further, the present findings suggested that the induced ipsilateral bias may be primarily induced by visual deprivation, consistent with compensatory "where" resource re-allocation.

False localizing signs in traumatic brain injury.

BACKGROUND: Hemiparesis ipsilateral to a mass-occupying lesion can be due to Kernohan-Woltman Notch Phenomenon (KWNP). This syndrome implies a false-localizing sign because clinical findings lead the examiner to an incorrect neuroanatomical diagnosis. The contralateral crus cerebri (pyramidal tract) is pressed against the tentorial incisum and a resultant hemiparesis is found on the same side of the lesion. REVIEW: A detailed literature search of false-localizing signs is presented. CONCLUSIONS: Not infrequently, patients presenting to a physiatrist may have incomplete records. The existence of false localizing signs may point the physician towards the wrong underlying pathology.

Is it what you see, or how you say it? Spatial bias in young and aged subjects.

Healthy subjects demonstrate leftward bias on visual-spatial tasks. However, young controls may also be left-biased when drawing communicatively, depicting the subject of a sentence leftward on a page relative to the sentence object, that is, a spatial-syntactic, implicit task. A leftward visual-spatial bias may decrease with aging, as right-hemisphere, dorsal, visual-spatial activation may be reduced in elderly subjects performing these tasks. We compared horizontal and radial (near-far) visual spatial bias, and spatial-syntactic bias, in healthy young and aged participants. Both horizontal and radial visual-spatial bias were smaller in aged participants when explicitly, but not implicitly assessed. Mean implicit far bias was greater in aged subjects, although this varied by task. We observed less implicit, spatial-syntactic left bias in aged than young participants. These results may be consistent with relatively less dominance of right hemisphere, dorsal spatial systems with aging.

Perceptual-attentional and motor-intentional bias in near and far space.

Spatial bias demonstrated in tasks such as line-bisection may stem from perceptual-attentional (PA) "where" and motor-intentional (MI) "aiming" influences. We tested normal participants' line bisection performance in the presence of an asymmetric visual distracter with a video apparatus designed to dissociate PA from MI bias. An experimenter stood as a distractor to the left or right of a video monitor positioned in either near or far space, where participants viewed lines and a laser point they directed under (1) natural and (2) mirror-reversed conditions. Each trial started with the pointer positioned at either the top left or top right corner of the screen, and alternated thereafter. Data analysis indicated that participants made primarily PA leftward errors in near space, but not in far space. Furthermore, PA, but not MI, bias increased bilaterally in the direction of distraction. In contrast, MI, but not PA, bias was shifted bilaterally in the direction of startside. Results support the conclusion that a primarily PA left sided bias in near space is consistent with right hemisphere spatial attentional dominance. A bottom-up visual distractor specifically affected PA "where" spatial bias while top-down motor cuing influenced MI "aiming" bias.