The neural correlates of cognitive time management: a review

Cognitive time management is an important aspect of human behaviour and cognition that has so far been understudied. Functional imaging studies in recent years have tried to identify the neural correlates of several timing functions, ranging from simple motor tapping to higher cognitive time estimation functions. Several regions of the frontal lobes, in particular dorsolateral prefrontal cortex (DLPFC), inferior prefrontal cortex (IFC), anterior cingulate gyrus (ACG) and the supplementary motor area (SMA), alongside non-frontal brain regions such as the inferior parietal lobes, the cerebellum and the basal ganglia have been found to be involved in tasks of motor timing and time estimation. In this paper we review and discuss the involvement of these brain regions in different tasks of cognitive time management, illustrating it with own findings on motor timing and time perception tasks using functional magnetic resonance imaging (fMRI). The review shows that the same brain regions are involved in both motor timing and time estimation, suggesting that both functions are probably inseparable and mediated by common neural networks.     

The influence of aging and frontal function on the neural correlates of regulative and evaluative aspects of cognitive control

The influence of aging and frontal function on the neural correlates of regulative and evaluative control was examined by means of event-related brain potentials (ERPs). The behavioral data indicated that interference was greater for older than for younger adults and that this difference was mediated by frontal function. The ERP data revealed effects of aging on the neural correlates of both regulative and evaluative control. Prestimulus neural activity was correlated with response time and frontal function, and these relationships were moderated by the response-to-stimulus interval (RSI); the poststimulus data also revealed age-related differences in the neural correlates of evaluative control that interacted with RSI. These data support predictions derived from the context processing deficit theory of aging.     

Absolute pitch: a model for understanding the influence of genes and development on neural and cognitive function

Absolute pitch (AP), the ability to identify or produce the pitch of a sound without any reference point, is discussed here as a possible model system for understanding the neurobiology of complex cognitive functions. AP is of interest because it may reflect an atypical organization of sensory representations. Indications are that it depends on both genetic factors and exposure to musical training during childhood, supporting the idea of a sensitive period. Functional and structural neuroimaging studies suggest special roles for working memory and associative memory mechanisms in AP, and results from these studies indicate that there may be structural markers of AP in asymmetries of cortical areas. AP seems to depend on the nervous system's response to experiential, maturational and genetic factors, making it a good candidate model for understanding how these interactions play out in cognitive development generally.     

Masticatory function and cognitive function

Recent studies have suggest that masticatory (chewing) function is useful for maintaining neurocognitive function in the elderly. For example, a reduced ability to masticate, such as that resulting from toothlessness or soft-diet feeding, causes learning and memory deficits in aged animals and pathologic changes in the hippocampus. In addition, occlusal disharmony impairs hippocampal memory processes via chronic stress, and induces similar hippocampal pathology. Chewing, however, rescues stress-induced suppression of long-term potentiation in the hippocampus and the stress-induced impairment of hippocampal-dependent learning. These findings strongly suggest a link between mastication and neurocognitive function.     

神经干细胞移植对痴呆大鼠记忆功能及海马组织氧化应激的影响

目的 研究神经干细胞移植对β淀粉样蛋白(Aβ1-40)所致痴呆大鼠记忆功能及海马组织丙二醛(MDA)、超氧化物岐化酶(SOD)的影响.方法 取新生大鼠脑皮质进行神经干细胞的分离、培养、鉴定,传代培养2-3代;选取30只健康SD大鼠随机分为3组,10只,组.对照组:侧脑室注入蒸馏水5μl;模型组:侧脑室注入Aβ1-40 ...     

Phytoestrogens and cognitive function: a review

Neuroprotective effects of phytoestrogen compounds (found in soy) have been demonstrated in animal research and cell culture studies. In particular, phytoestrogens have been shown to reduce Alzheimer's Disease (AD) related pathology, potentially alleviating risk of AD progression. In addition to their antioxidant properties, soy products also have the ability to affect cognition via interaction with estrogen receptors. However, observational studies and randomised controlled trials in humans have resulted in inconclusive findings within this domain. There are several possible reasons for these discrepant data. Studies which report no effect of phytoestrogens on cognition have mainly been carried out in European cohorts, with an average low dietary consumption. In contrast, investigation of Asian populations, with a higher general intake of tofu (a non-fermented soy product) have shown negative associations with cognitive function in those over the age of 65. Consideration of type of soy product is important, as in the latter sample, protective effects of tempe (fermented soy) were also observed. Limited data provide evidence that effects of phytoestrogens on cognition may be modified by dosage, duration of consumption and cognitive test used. Additionally, characteristics of the study population including age, gender, ethnicity and menopausal status appear to be mediating variables. Phytoestrogen treatment interventions have also shown time-limited positive effects on cognition. These findings are consistent with estrogen treatment studies, where initial positive short-term cognitive effects may occur, which reverse with long-term continuous use in elderly women. Well controlled, large scale studies are needed to assess the effects of phytoestrogens on the aging brain and provide further understanding of this association.     

Grandiose delusions: a review and theoretical integration of cognitive and affective perspectives

Grandiose delusions (GDs) are found across a wide range of psychiatric conditions, including in around two-thirds of patients diagnosed with bipolar disorder, half of patients diagnosed with schizophrenia, as well as in a substantial proportion of patients with substance abuse disorders. In addition, over 10% of the healthy general population experience grandiose thoughts that do not meet full delusional criteria. Yet in contrast to other psychotic phenomena, such as auditory hallucinations and persecutory delusions, GDs have received little attention from researchers. This paper offers a comprehensive examination of the existing cognitive and affective literature on GDs, including consideration of the evidence in support of ‘delusion-as-defence’ and emotion-consistent’ models. We then propose a tentative model of GDs informed by a synthesis of the available evidence designed to be a stimulus to future research in this area. As GDs are considered to be relatively resistant to traditional cognitive behavioural techniques, we then discuss the implications of our model for how CBT may be modified to address these beliefs. Directions for future research are also highlighted.     

The neural correlates of cognitive effort in anxiety: effects on processing efficiency

We investigated the neural correlates of cognitive effort/pre-target preparation (Contingent Negative Variation activity; CNV) in anxiety using a mixed antisaccade task that manipulated the interval between offset of instructional cue and onset of target (CTI). According to attentional control theory (Eysenck et al., 2007) we predicted that anxiety should result in increased levels of compensatory effort, as indicated by greater frontal CNV, to maintain comparable levels of performance under competing task demands. Our results showed that anxiety resulted in faster antisaccade latencies during medium compared with short and long CTIs. Accordingly, high-anxious individuals compared with low-anxious individuals showed greater levels of CNV activity at frontal sites during medium CTI suggesting that they exerted greater cognitive effort and invested more attentional resources in preparation for the task goal. Our results are the first to demonstrate the neural correlates of processing efficiency and compensatory effort in anxiety and are discussed within the framework of attentional control theory.     

The roots of modern justice: cognitive and neural foundations of social norms and their enforcement

Among animals, Homo sapiens is unique in its capacity for widespread cooperation and prosocial behavior among large and genetically heterogeneous groups of individuals. This ultra-sociality figures largely in our success as a species. It is also an enduring evolutionary mystery. There is considerable support for the hypothesis that this facility is a function of our ability to establish, and enforce through sanctions, social norms. Third-party punishment of norm violations ("I punish you because you harmed him") seems especially crucial for the evolutionary stability of cooperation and is the cornerstone of modern systems of criminal justice. In this commentary, we outline some potential cognitive and neural processes that may underlie the ability to learn norms, to follow norms and to enforce norms through third-party punishment. We propose that such processes depend on several domain-general cognitive functions that have been repurposed, through evolution's thrift, to perform these roles.     

Working memory for order information: multiple cognitive and neural mechanisms

Working memory for order information is mediated by different cognitive mechanisms that rely on different neural circuits. Here we discuss evidence that order memory involves mechanisms that range from general supervisory processes to process that maintenance fine-grained temporal position information. We suggest that neural regions-including the prefrontal cortex, motor cortex, parietal cortex and medial temporal structures-operate at different levels and processing stages to give rise to working memory for order information.     

The role of sensorimotor learning in the perception of letter-like forms: tracking the causes of neural specialization for letters

Functional specialization in the brain is considered a hallmark of efficient processing. It is therefore not surprising that there are brain areas specialized for processing letters. To better understand the causes of functional specialization for letters, we explore the emergence of this pattern of response in the ventral processing stream through a training paradigm. Previously, we hypothesized that the specialized response pattern seen during letter perception may be due in part to our experience in writing letters. The work presented here investigates whether or not this aspect of letter processing-the integration of sensorimotor systems through writing-leads to functional specialization in the visual system. To test this idea, we investigated whether or not different types of experiences with letter-like stimuli ("pseudoletters") led to functional specialization similar to that which exists for letters. Neural activation patterns were measured using functional magnetic resonance imaging (fMRI) before and after three different types of training sessions. Participants were trained to recognize pseudoletters by writing, typing, or purely visual practice. Results suggested that only after writing practice did neural activation patterns to pseudoletters resemble patterns seen for letters. That is, neural activation in the left fusiform and dorsal precentral gyrus was greater when participants viewed pseudoletters than other, similar stimuli but only after writing experience. Neural activation also increased after typing practice in the right fusiform and left precentral gyrus, suggesting that in some areas, any motor experience may change visual processing. The results of this experiment suggest an intimate interaction among perceptual and motor systems during pseudoletter perception that may be extended to everyday letter perception.     

Aortic elastic properties and cognitive function in elderly individuals: The Ikaria Study

BackgroundThe aim of this work was to evaluate the association between aortic elastic properties and cognitive function in elderly individuals, permanent inhabitants of Ikaria Island.MethodsIn 535 individuals (75 ± 6 years, 53% males) aortic distensibility (AoD) was non-invasively calculated from the aortic diameters measured with echocardiography and brachial artery pressure using the formula by Stefanadis et al.; cognitive status was evaluated using the Mini Mental State Examination (MMSE).Results88% of the elders had normal values of MMSE score (i.e., ≥24). Elders who achieved MMSE score ≥24 had higher values of AoD (1.90 ± 2.06 vs. 1.08 ± 1.42, p < 0.001), as well as were more physically active (85% vs. 69%, p = 0.05), had higher educational status (8.5 ± 2.8 years vs. 6 ± 2 years, p = 0.001), higher creatinine clearance levels (70 ± 21 vs. 63 ± 23, p = 0.05) and lower pulse pressure (PP) values (63 ± 16 vs. 68 ± 18, p = 0.06), as compared with those individuals with MMSE < 24. Logistic regression analysis showed that for every unit increase in AoD there was a 25% higher likelihood of having MMSE ≥ 24 (OR per 1000 × mmHg^?1 = 1.25, 95%CI 0.99–1.58), after adjustments for age, gender, current smoking, cardiovascular disease, creatinine clearance, hypertension, diabetes mellitus, obesity, physical activity status and education status. Furthermore having PP levels in the upper tertile (>70 mmHg), increases by 55% the likelihood of having MMSE < 24 (OR for above 70 mmHg = 0.45, 95%CI 0.22, 0.92), after the same adjustments were made.ConclusionArterial aging seems to affect cognitive function; a finding that states a novel research hypothesis about the pathophysiological mechanisms of mental functioning.     

Diabetes insipidus and cognitive function

It has been well known that several neuropeptides may affect human behavior, and that some endocrinopathies are associated with impaired higher function of the brain. There have been increasing evidences that vasopressin has both peripheral and central effects, the latter of which is involved in memory. In experimental animals, male mice with a null mutation in the V1a receptor (V1aR) exhibit a profound impairment in social recognition and changes in anxiety-like behavior. An AVP fragment analog has been reported to facilitate memory retention and recall in mice through protein kinase C-independent pathways. In human, a few recent reports have suggested that a familial central diabetes insipidus, caused by a heterozygous mutation in the gene for vasopressin prohormone, have minor disturbances in central nervous system. Taken together, it is hypothesized that the subject with central diabetes insipidus may frequently present with an impaired cognitive ability. It is justified to examine the cognitive function, when we make a diagnosis of central diabetes insipidus and to perform a clinical study to investigate whether central diabetes insipidus may be associated with impairment of higher brain functions.     

Improvement of cognitive function and physical activity of aging mice by human neural stem cells over-expressing choline acetyltransferase

Aging is characterized by progressive loss of cognitive and memory functions as well as decrease in physical activities. In the present study, a human neural stem cell line (F3 NSC) over-expressing choline acetyltransferase (F3.ChAT), an enzyme responsible for acetylcholine synthesis, was generated and transplanted in the brain of 18-month-old male ICR mice. Four weeks post-transplantation, neurobehavioral functions, expression of ChAT enzyme, production of acetylcholine and neurotrophic factors, and expression of cholinergic nervous system markers in transplanted animals were investigated. F3.ChAT NSCs markedly improved both the cognitive function and physical activity of aging animals, in parallel with the elevation of brain acetylcholine level. Transplanted F3 and F3.ChAT cells were found to differentiate into neurons and astrocytes, and to produce ChAT proteins. Transplantation of the stem cells increased brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), enhanced expression of Trk B, and restored host microtubule-associated protein 2 and cholinergic nervous system. The results demonstrate that human NSCs over-expressing ChAT improve cognitive function and physical activity of aging mice, not only by producing ACh directly but also by restoring cholinergic neuronal integrity, which might be mediated by neurotrophins BDNF and NGF.     

Anatomical perspectives on adult neural stem cells

The concept of stem cells within the adult brain is not new. However, only recently have scientific techniques become sufficiently advanced to identify them although this remains problematic and the technology is still developing. Nevertheless, it is now generally recognized that stem cells are restricted to two germinal regions within the intact brain. From here they can migrate to specific destinations where they integrate with existing circuitry. Their identity remains controversial but a growing body of evidence suggests it may have an astrocytic phenotype. Within the germinal regions the stem cells are confined to a niche environment and are capable of responding to environmental signals generated locally in an autocrine or paracrine fashion. The niche environment is also modulated by more generalized systemic and physiological activity. These observations are exciting in their own right and form the basis of this review. They are also beginning to alter how we think about neural injury and disease and to impact on the development of novel therapies.