Understanding Ancient Hominin Dispersals Using Artefactual Data: A Phylogeographic Analysis of Acheulean Handaxes

Background

Reconstructing the dispersal patterns of extinct hominins remains a challenging but essential goal. One means of supplementing fossil evidence is to utilize archaeological evidence in the form of stone tools. Based on broad dating patterns, it has long been thought that the appearance of Acheulean handaxe technologies outside of Africa was the result of hominin dispersals, yet independent tests of this hypothesis remain rare. Cultural transmission theory leads to a prediction of a strong African versus non-African phylogeographic pattern in handaxe datasets, if the African Acheulean hypothesis is to be supported.

Methodology/Principal Findings

Here, this prediction is tested using an intercontinental dataset of Acheulean handaxes and a biological phylogenetic method (maximum parsimony). The analyses produce a tree consistent with the phylogeographic prediction. Moreover, a bootstrap analysis provides evidence that this pattern is robust, and the maximum parsimony tree is also shown to be statistically different from a tree constrained by stone raw materials.

Conclusions/Significance

These results demonstrate that nested analyses of behavioural data, utilizing methods drawn from biology, have the potential to shed light on ancient hominin dispersals. This is an encouraging prospect for human palaeobiology since sample sizes for lithic artefacts are many orders of magnitude higher than those of fossil data. These analyses also suggest that the sustained occurrence of Acheulean handaxe technologies in regions such as Europe and the Indian subcontinent resulted from dispersals by African hominin populations.     

Shared Brain Lateralization Patterns in Language and Acheulean Stone Tool Production: A Functional Transcranial Doppler Ultrasound Study

Background

The popular theory that complex tool-making and language co-evolved in the human lineage rests on the hypothesis that both skills share underlying brain processes and systems. However, language and stone tool-making have so far only been studied separately using a range of neuroimaging techniques and diverse paradigms.

Methodology/Principal Findings

We present the first-ever study of brain activation that directly compares active Acheulean tool-making and language. Using functional transcranial Doppler ultrasonography (fTCD), we measured brain blood flow lateralization patterns (hemodynamics) in subjects who performed two tasks designed to isolate the planning component of Acheulean stone tool-making and cued word generation as a language task. We show highly correlated hemodynamics in the initial 10 seconds of task execution.

Conclusions/Significance

Stone tool-making and cued word generation cause common cerebral blood flow lateralization signatures in our participants. This is consistent with a shared neural substrate for prehistoric stone tool-making and language, and is compatible with language evolution theories that posit a co-evolution of language and manual praxis. In turn, our results support the hypothesis that aspects of language might have emerged as early as 1.75 million years ago, with the start of Acheulean technology.     

Behavior Matters—Cognitive Predictors of Survival in Amyotrophic Lateral Sclerosis

Background

It is difficult to longitudinally characterize cognitive impairment in amyotrophic lateral sclerosis (ALS) due to motor deficits, and existing instruments aren’t comparable with assessments in other dementias.

Methods

The ALS Brief Cognitive Assessment (ALS-BCA) was validated in 70 subjects (37 with ALS) who also underwent detailed neuropsychological analysis. Cognitive predictors for poor survival were then analyzed in a longitudinal cohort of 171 ALS patients.

Results

The ALS-BCA was highly sensitive (90%) and specific (85%) for ALS-dementia (ALS-D). ALS-D patients had shorter overall survival, primarily due to the poor survival among ALS-D patients with disinhibited or apathetic behaviors after adjusting for demographic variables, ALS site of onset, medications, and supportive measures. ALS-D without behavioral changes was not a predictor of poor survival.

Conclusion

ALS-D can present with or without prominent behavioral changes. Cognitive screening in ALS patients should focus on behavioral changes for prognosis, while non-behavioral cognitive impairments may impact quality of life without impacting survival.     

Amantadine Ameliorates Dopamine-Releasing Deficits and Behavioral Deficits in Rats after Fluid Percussion Injury

Aims

To investigate the role of dopamine in cognitive and motor learning skill deficits after a traumatic brain injury (TBI), we investigated dopamine release and behavioral changes at a series of time points after fluid percussion injury, and explored the potential of amantadine hydrochloride as a chronic treatment to provide behavioral recovery.

Materials and Methods

In this study, we sequentially investigated dopamine release at the striatum and behavioral changes at 1, 2, 4, 6, and 8 weeks after fluid percussion injury. Rats subjected to 6-Pa cerebral cortical fluid percussion injury were treated by using subcutaneous infusion pumps filled with either saline (sham group) or amantadine hydrochloride, with a releasing rate of 3.6mg/kg/hour for 8 weeks. The dopamine-releasing conditions and metabolism were analyzed sequentially by fast scan cyclic voltammetry (FSCV) and high-pressure liquid chromatography (HPLC). Novel object recognition (NOR) and fixed-speed rotarod (FSRR) behavioral tests were used to determine treatment effects on cognitive and motor deficits after injury.

Results

Sequential dopamine-release deficits were revealed in 6-Pa-fluid-percussion cerebral cortical injured animals. The reuptake rate (tau value) of dopamine in injured animals was prolonged, but the tau value became close to the value for the control group after amantadine therapy. Cognitive and motor learning impairments were shown evidenced by the NOR and FSRR behavioral tests after injury. Chronic amantadine therapy reversed dopamine-release deficits, and behavioral impairment after fluid percussion injuries were ameliorated in the rats treated by using amantadine-pumping infusion.

Conclusion

Chronic treatment with amantadine hydrochloride can ameliorate dopamine-release deficits as well as cognitive and motor deficits caused by cerebral fluid-percussion injury.     

Clinical Application of Estimating Hepatitis B Virus Quasispecies Complexity by Massive Sequencing: Correlation between Natural Evolution and On-Treatment Evolution

Aim

To evaluate HBV quasispecies (QA) complexity in the preCore/Core regions in relation to HBeAg status, and explore QA changes under natural evolution and nucleoside analogue (NUC) treatment.

Methods

Ultra-deep pyrosequencing of HBV preCore/Core regions in 30 sequential samples (baseline [diagnosis], treatment-free, and treatment-nonresponse) from 10 retrospectively selected patients grouped according to HBeAg status over time: HBeAg+ (N = 4), HBeAg- (N = 2), and fluctuating HBeAg (transient seroreversion/seroconversion pattern) (N = 4). QA complexity was defined by Shannon entropy, mutation frequency, nucleotide diversity, and mutation frequency of amino acids (MfAA) in preCore and Core.

Results

The QA was less complex in HBeAg+ than in HBeAg- or fluctuating HBeAg. High complexity in preCore was associated with decreased viral replication (preCore MfAA negatively correlated with HBV-DNA, p = 0.005). QA complexity in the treatment-free period negatively correlated with values seen during treatment. Specific variants were mainly selected in the Core region in HBeAg- and fluctuating HBeAg patients, suggesting higher immune pressure than in HBeAg+.

Conclusions

The negative correlation between QA natural evolution and on-treatment evolution indicates the importance of pre-treatment QA study to predict QA changes in NUC nonresponders. Study of QA complexity could be useful for managing HBV infection.     

Khat use is associated with impaired working memory and cognitive flexibility

Rationale

Khat consumption has increased during the last decades in Eastern Africa and has become a global phenomenon spreading to ethnic communities in the rest of the world, such as The Netherlands, United Kingdom, Canada, and the United States. Very little is known, however, about the relation between khat use and cognitive control functions in khat users.

Objective

We studied whether khat use is associated with changes in working memory (WM) and cognitive flexibility, two central cognitive control functions.

Methods

Khat users and khat-free controls were matched in terms of sex, ethnicity, age, alcohol and cannabis consumption, and IQ (Raven''s progressive matrices). Groups were tested on cognitive flexibility, as measured by a Global-Local task, and on WM using an N-back task.

Result

Khat users performed significantly worse than controls on tasks tapping into cognitive flexibility as well as monitoring of information in WM.

Conclusions

The present findings suggest that khat use impairs both cognitive flexibility and the updating of information in WM. The inability to monitor information in WM and to adjust behavior rapidly and flexibly may have repercussions for daily life activities.     

Complex Prospective Memory in Adults with Attention Deficit Hyperactivity Disorder

Objectives

Attention deficit hyperactivity disorder (ADHD) in adults has been associated with disturbances of attention and executive functions. Furthermore, impairments of verbal and figural retrospective memory were reported. However, little is known about the effects of ADHD on prospective memory, the execution of delayed intentions in the future.

Methods

The present study compared the performance of 45 adult patients with ADHD not treated with stimulant medication with the performance of 45 matched healthy individuals on a paradigm of complex prospective memory which measured task planning, plan recall, self-initiation and execution. Furthermore, the contribution of other cognitive functions to prospective memory functioning was assessed, including measures of attention, executive functions and memory.

Results

A large-scale impairment could be observed in task planning abilities in patients with ADHD. Only negligible to small effects were found for plan recall, self-initiation and execution. Inhibition was identified to contribute significantly to performance on task planning.

Conclusions

The present findings suggest that four cognitive components contribute to the performance of prospective memory. Impairments of prospective memory mainly emerged from deficient planning abilities in adults with ADHD. Implications on behavioral based intervention strategies are discussed.     

Early PTSD Symptom Trajectories: Persistence,Recovery, and Response to Treatment: Results from the Jerusalem Trauma Outreach and Prevention Study (J-TOPS)

Context

Uncovering heterogeneities in the progression of early PTSD symptoms can improve our understanding of the disorder''s pathogenesis and prophylaxis.

Objectives

To describe discrete symptom trajectories and examine their relevance for preventive interventions.

Design

Latent Growth Mixture Modeling (LGMM) of data from a randomized controlled study of early treatment. LGMM identifies latent longitudinal trajectories by exploring discrete mixture distributions underlying observable data.

Setting

Hadassah Hospital unselectively receives trauma survivors from Jerusalem and vicinity.

Participants

Adult survivors of potentially traumatic events consecutively admitted to the hospital''s emergency department (ED) were assessed ten days and one-, five-, nine- and fifteen months after ED admission. Participants with data at ten days and at least two additional assessments (n = 957) were included; 125 received cognitive behavioral therapy (CBT) between one and nine months.

Approach

We used LGMM to identify latent parameters of symptom progression and tested the effect of CBT on these parameters. CBT consisted of 12 weekly sessions of either cognitive therapy (n = 41) or prolonged exposure (PE, n = 49), starting 29.8±5.7 days after ED admission, or delayed PE (n = 35) starting at 151.8±42.4 days. CBT effectively reduced PTSD symptoms in the entire sample.

Main Outcome Measure

Latent trajectories of PTSD symptoms; effects of CBT on these trajectories.

Results

Three trajectories were identified: Rapid Remitting (rapid decrease in symptoms from 1- to 5-months; 56% of the sample), Slow Remitting (progressive decrease in symptoms over 15 months; 27%) and Non-Remitting (persistently elevated symptoms; 17%). CBT accelerated the recovery of the Slow Remitting class but did not affect the other classes.

Conclusions

The early course of PTSD symptoms is characterized by distinct and diverging response patterns that are centrally relevant to understanding the disorder and preventing its occurrence. Studies of the pathogenesis of PTSD may benefit from using clustered symptom trajectories as their dependent variables.     

Prenatal Origins of Temperament: Fetal Growth,Brain Structure,and Inhibitory Control in Adolescence

Objective

Individual differences in the temperamental dimension of effortful control are constitutionally based and have been associated with an adverse prenatal developmental environment, with structural brain alterations presenting a potential mechanism. We investigated this hypothesis for anatomically defined brain regions implicated in cognitive and inhibitory motor control.

Methods

Twenty-seven 15–16 year old participants with low, medium, or high fetal growth were selected from a longitudinal birth cohort to maximize variation and represent the full normal spectrum of fetal growth. Outcome measures were parent ratings of attention and inhibitory control, thickness and surface area of the orbitofrontal cortex (lateral (LOFC) and medial (MOFC)) and right inferior frontal gyrus (rIFG), and volumetric measures of the striatum and amygdala.

Results

Lower birth weight was associated with lower inhibitory control, smaller surface area of LOFC, MOFC and rIFG, lower caudate volume, and thicker MOFC. A mediation model found a significant indirect effect of birth weight on inhibitory control via caudate volume.

Conclusions

Our findings support a neuroanatomical mechanism underlying potential long-term consequences of an adverse fetal developmental environment for behavioral inhibitory control in adolescence and have implications for understanding putative prenatal developmental origins of externalizing behavioral problems and self-control.     

Treatment Efficacy for Non-Cardiovascular Chest Pain: A Systematic Review and Meta-Analysis

Background

Non-cardiovascular chest pain (NCCP) leads to impaired quality of life and is associated with a high disease burden. Upon ruling out cardiovascular disease, only vague recommendations exist for further treatment.

Objectives

To summarize treatment efficacy for patients presenting with NCCP.

Methods

Systematic review and meta-analysis. In July 2013, Medline, Web of Knowledge, Embase, EBSCOhost, Cochrane Reviews and Trials, and Scopus were searched. Hand and bibliography searches were also conducted. Randomized controlled trials (RCTs) evaluating non-surgical treatments in patients with NCCP were included. Exclusion criteria were poor study quality and small sample size (<10 patients per group).

Results

Thirty eligible RCT’s were included. Most studies assessed PPI efficacy for gastroesophageal reflux disorders (GERD, n = 10). Two RCTs included musculoskeletal chest pain, seven psychotropic drugs, and eleven various psychological interventions. Study quality was high in five RCTs and acceptable in 25. PPI treatment in patients with GERD (5 RCTs, 192 patients) was more effective than placebo [pooled OR 11.7 (95% CI 5.5 to 25.0, heterogeneity I² = 6.1%)]. The pooled OR in GERD negative patients (4 RCTs, 156 patients) was 0.8 (95% CI 0.2 to 2.8, heterogeneity I² = 50.4%). In musculoskeletal NCCP (2 RCTs, 229 patients) manual therapy was more effective than usual care but not than home exercise [pooled mean difference 0.5 (95% CI −0.3 to 1.3, heterogeneity I² = 46.2%)]. The findings for cognitive behavioral treatment, serotonin reuptake inhibitors, tricyclic antidepressants were mixed. Most evidence was available for cognitive behavioral treatment interventions.

Limitations

Only a small number of studies were available.

Conclusions

Timely diagnostic evaluation and treatment of the disease underlying NCCP is important. For patients with suspected GERD, high-dose treatment with PPI is effective. Only limited evidence was available for most prevalent diseases manifesting with chest pain. In patients with idiopathic NCCP, treatments based on cognitive behavioral principles might be considered.     

Increased Cortical Activity in Binge Drinkers during Working Memory Task: A Preliminary Assessment through a Functional Magnetic Resonance Imaging Study

Background

Cerebral dysfunction is a common feature of both chronic alcohol abusers and binge drinkers. Here, we aimed to study whether, at equated behavioral performance levels, binge drinkers exhibited increased neural activity while performing simple cognitive tasks.

Methods

Thirty-two participants (16 binge drinkers and 16 matched controls) were scanned using functional magnetic resonance imaging (fMRI) while performing an n-back working memory task. In the control zero-back (N0) condition, subjects were required to press a button with the right hand when the number “2″ was displayed. In the two-back (N2) condition, subjects had to press a button when the displayed number was identical to the number shown two trials before.

Results

fMRI analyses revealed higher bilateral activity in the pre-supplementary motor area in binge drinkers than matched controls, even though behavioral performances were similar. Moreover, binge drinkers showed specific positive correlations between the number of alcohol doses consumed per occasion and higher activity in the dorsomedial prefrontal cortex, as well as between the number of drinking occasions per week and higher activity in cerebellum, thalamus and insula while performing the N2 memory task.

Conclusions

Binge alcohol consumption leads to possible compensatory cerebral changes in binge drinkers that facilitate normal behavioral performance. These changes in cerebral responses may be considered as vulnerability factors for developing adult substance use disorders.     

Oldest Evidence of Toolmaking Hominins in a Grassland-Dominated Ecosystem

Background

Major biological and cultural innovations in late Pliocene hominin evolution are frequently linked to the spread or fluctuating presence of C₄ grass in African ecosystems. Whereas the deep sea record of global climatic change provides indirect evidence for an increase in C₄ vegetation with a shift towards a cooler, drier and more variable global climatic regime beginning approximately 3 million years ago (Ma), evidence for grassland-dominated ecosystems in continental Africa and hominin activities within such ecosystems have been lacking.

Methodology/Principal Findings

We report stable isotopic analyses of pedogenic carbonates and ungulate enamel, as well as faunal data from ∼2.0 Ma archeological occurrences at Kanjera South, Kenya. These document repeated hominin activities within a grassland-dominated ecosystem.

Conclusions/Significance

These data demonstrate what hitherto had been speculated based on indirect evidence: that grassland-dominated ecosystems did in fact exist during the Plio-Pleistocene, and that early Homo was active in open settings. Comparison with other Oldowan occurrences indicates that by 2.0 Ma hominins, almost certainly of the genus Homo, used a broad spectrum of habitats in East Africa, from open grassland to riparian forest. This strongly contrasts with the habitat usage of Australopithecus, and may signal an important shift in hominin landscape usage.     

Cognitive Training Improves Sleep Quality and Cognitive Function among Older Adults with Insomnia

Study Objectives

To investigate the effect of an eight-week, home-based, personalized, computerized cognitive training program on sleep quality and cognitive performance among older adults with insomnia.

Design

Participants (n = 51) were randomly allocated to a cognitive training group (n = 34) or to an active control group (n = 17). The participants in the cognitive training group completed an eight-week, home-based, personalized, computerized cognitive training program, while the participants in the active control group completed an eight-week, home-based program involving computerized tasks that do not engage high-level cognitive functioning. Before and after training, all participants'' sleep was monitored for one week by an actigraph and their cognitive performance was evaluated.

Setting

Community setting: residential sleep/performance testing facility.

Participants

Fifty-one older adults with insomnia (aged 65–85).

Interventions

Eight weeks of computerized cognitive training for older adults with insomnia.

Results

Mixed models for repeated measures analysis showed between-group improvements for the cognitive training group on both sleep quality (sleep onset latency and sleep efficiency) and cognitive performance (avoiding distractions, working memory, visual memory, general memory and naming). Hierarchical linear regressions analysis in the cognitive training group indicated that improved visual scanning is associated with earlier advent of sleep, while improved naming is associated with the reduction in wake after sleep onset and with the reduction in number of awakenings. Likewise the results indicate that improved “avoiding distractions” is associated with an increase in the duration of sleep. Moreover, the results indicate that in the active control group cognitive decline observed in working memory is associated with an increase in the time required to fall asleep.

Conclusions

New learning is instrumental in promoting initiation and maintenance of sleep in older adults with insomnia. Lasting and personalized cognitive training is particularly indicated to generate the type of learning necessary for combined cognitive and sleep enhancements in this population.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00901641","term_id":"NCT00901641"}}NCT00901641http://clinicaltrials.gov/ct2/show/NCT00901641     

The Queen and I: Neural Correlates of Altered Self-Related Cognitions in Major Depressive Episode

Background

Pervasive negative thoughts about the self are central to the experience of depression. Brain imaging studies in the general population have localised self-related cognitive processing to areas of the medial pre-frontal cortex.

Aims

To use fMRI to compare the neural correlates of self-referential processing in depressed and non-depressed participants.

Method

Cross-sectional comparison of regional activation using Blood Oxygen Level Dependent (BOLD) fMRI in 13 non-medicated participants with major depressive episode and 14 comparison participants, whilst carrying out a self-referential cognitive task.

Results

Both groups showed significant activation of the dorsomedial pre-frontal cortex and posterior cingulate cortex in the ‘self-referent’ condition. The depressed group showed significantly greater activation in the medial superior frontal cortex during the self-referent task. No difference was observed between groups in the ‘other-referent’ condition.

Conclusions

Major depressive episode is associated with specific neurofunctional changes related to self-referential processing.     

Cardiovascular Disease Risk Models and Longitudinal Changes in Cognition: A Systematic Review

Background

Cardiovascular disease and its risk factors have consistently been associated with poor cognitive function and incident dementia. Whether cardiovascular disease prediction models, developed to predict an individual''s risk of future cardiovascular disease or stroke, are also informative for predicting risk of cognitive decline and dementia is not known.

Objective

The objective of this systematic review was to compare cohort studies examining the association between cardiovascular disease risk models and longitudinal changes in cognitive function or risk of incident cognitive impairment or dementia.

Materials and Methods

Medline, PsychINFO, and Embase were searched from inception to March 28, 2014. From 3,413 records initially screened, 21 were included.

Results

The association between numerous different cardiovascular disease risk models and cognitive outcomes has been tested, including Framingham and non-Framingham risk models. Five studies examined dementia as an outcome; fourteen studies examined cognitive decline or incident cognitive impairment as an outcome; and two studies examined both dementia and cognitive changes as outcomes. In all studies, higher cardiovascular disease risk scores were associated with cognitive changes or risk of dementia. Only four studies reported model prognostic performance indices, such as Area Under the Curve (AUC), for predicting incident dementia or cognitive impairment and these studies all examined non-Framingham Risk models (AUC range: 0.74 to 0.78).

Conclusions

Cardiovascular risk prediction models are associated with cognitive changes over time and risk of dementia. Such models are easily obtainable in clinical and research settings and may be useful for identifying individuals at high risk of future cognitive decline and dementia.     

Cognitive Reactivity,Implicit Associations,and the Incidence of Depression: A Two-Year Prospective Study

Background

Cognitive reactivity to sad mood is a vulnerability marker of depression. Implicit self-depressed associations are related to depression status and reduced remission probability. It is unknown whether these cognitive vulnerabilities precede the first onset of depression.

Aim

To test the predictive value of cognitive reactivity and implicit self-depressed associations for the incidence of depressive disorders.

Methods

Prospective cohort study of 834 never-depressed individuals, followed over a two-year period. The predictive value of cognitive reactivity and implicit self-depressed associations for the onset of depressive disorders was assessed using binomial logistic regression. The multivariate model corrected for baseline levels of subclinical depressive symptoms, neuroticism, for the presence of a history of anxiety disorders, for family history of depressive or anxiety disorders, and for the incidence of negative life events.

Results

As single predictors, both cognitive reactivity and implicit self-depressed associations were significantly associated with depression incidence. In the multivariate model, cognitive reactivity was significantly associated with depression incidence, together with baseline depressive symptoms and the number of negative life events, whereas implicit self-depressed associations were not.

Conclusion

Cognitive reactivity to sad mood is associated with the incidence of depressive disorders, also when various other depression-related variables are controlled for. Implicit self-depressed associations predicted depression incidence in a bivariate test, but not when controlling for other predictors.     

Grey Matter Changes in Cognitively Impaired Parkinson's Disease Patients

Background

Cortical changes associated with cognitive decline in Parkinson''s disease (PD) are not fully explored and require investigations with established diagnostic classification criteria.

Objective

We used MRI source-based morphometry to evaluate specific differences in grey matter volume patterns across 4 groups of subjects: healthy controls (HC), PD with normal cognition (PD-NC), PD with mild cognitive impairment (MCI-PD) and PD with dementia (PDD).

Methods

We examined 151 consecutive subjects: 25 HC, 75 PD-NC, 29 MCI-PD, and 22 PDD at an Italian and Czech movement disorder centre. Operational diagnostic criteria were applied to classify MCI-PD and PDD. All structural MRI images were processed together in the Czech centre. The spatial independent component analysis was used to assess group differences of local grey matter volume.

Results

We identified two independent patterns of grey matter volume deviations: a) Reductions in the hippocampus and temporal lobes; b) Decreases in fronto-parietal regions and increases in the midbrain/cerebellum. Both patterns differentiated PDD from all other groups and correlated with visuospatial deficits and letter verbal fluency, respectively. Only the second pattern additionally differentiated PD-NC from HC.

Conclusion

Grey matter changes in PDD involve areas associated with Alzheimer-like pathology while fronto-parietal abnormalities are possibly an early marker of PD cognitive decline. These findings are consistent with a non-linear cognitive progression in PD.     

Tool-use training in a species of rodent: the emergence of an optimal motor strategy and functional understanding

Background

Tool use is defined as the manipulation of an inanimate object to change the position or form of a separate object. The expansion of cognitive niches and tool-use capabilities probably stimulated each other in hominid evolution. To understand the causes of cognitive expansion in humans, we need to know the behavioral and neural basis of tool use. Although a wide range of animals exhibit tool use in nature, most studies have focused on primates and birds on behavioral or psychological levels and did not directly address questions of which neural modifications contributed to the emergence of tool use. To investigate such questions, an animal model suitable for cellular and molecular manipulations is needed.

Methodology/Principal Findings

We demonstrated for the first time that rodents can be trained to use tools. Through a step-by-step training procedure, we trained degus (Octodon degus) to use a rake-like tool with their forelimbs to retrieve otherwise out-of-reach rewards. Eventually, they mastered effective use of the tool, moving it in an elegant trajectory. After the degus were well trained, probe tests that examined whether they showed functional understanding of the tool were performed. Degus did not hesitate to use tools of different size, colors, and shapes, but were reluctant to use the tool with a raised nonfunctional blade. Thus, degus understood the functional and physical properties of the tool after extensive training.

Conclusions/Significance

Our findings suggest that tool use is not a specific faculty resulting from higher intelligence, but is a specific combination of more general cognitive faculties. Studying the brains and behaviors of trained rodents can provide insights into how higher cognitive functions might be broken down into more general faculties, and also what cellular and molecular mechanisms are involved in the emergence of such cognitive functions.     

Homocysteine, grey matter and cognitive function in adults with cardiovascular disease

Background

Elevated total plasma homocysteine (tHcy) has been associated with cognitive impairment, vascular disease and brain atrophy.

Methods

We investigated 150 volunteers to determine if the association between high tHcy and cerebral grey matter volume and cognitive function is independent of cardiovascular disease.

Results

Participants with high tHcy (≥15 µmol/L) showed a widespread relative loss of grey matter compared with people with normal tHcy, although differences between the groups were minimal once the analyses were adjusted for age, gender, diabetes, hypertension, smoking and prevalent cardiovascular disease. Individuals with high tHcy had worse cognitive scores across a range of domains and less total grey matter volume, although these differences were not significant in the adjusted models.

Conclusions

Our results suggest that the association between high tHcy and loss of cerebral grey matter volume and decline in cognitive function is largely explained by increasing age and cardiovascular diseases and indicate that the relationship is not causal.