Sol-Gel Functionalized Polyurethane Foam-Packed Mini-Column as an Efficient Solid Extractor for the Rapid and Ultra-Trace Detection of Textile Dyes in Water.

Textile dyes widely used in industrial products are known as a major threat to human health and water ecological security. On the other hand, sol gel represents a principal driver of the adoption of dispersive solid-phase microextractors (d-µ SPME) for pollutants residues in water. Thus, the current study reports a new and highly rapid and highly efficient hybrid sol-gel-based sponge polyurethane foam as a dispersive solid-phase microextractor (d-µ-SPME) platform packed mini-column for complete preconcentration and subsequent spectrophotometric detection of eosin Y textile dye in wastewater. The unique porous structure of the prepared sol-gel immobilized polyurethane foams (sol-gel/PUF) has suggested its use for the complete removal of eosin Y dye (EY) from water. In the mini-column, the number (N) of plates, the height equivalent to the theoretical plates (HETP), the critical capacity (CC), and the breakthrough capacities (BC) of the hybrid sol-gel-treated polyurethane foams towards EY dye were determined via the breakthrough capacity curve at various flow rates. Under the optimum condition using the matrix match strategy, the linear range of 0.01-5 µg L-1, LODs and LOQs in the range of 0.006 µg L-1, and 0.01 µg L-1 for wastewater were achieved. The intra-day and inter-day precisions were evaluated at two different concentration levels (0.05 and 5 µg L-1 of dye) on the same day and five distinct days, respectively. The analytical utility of the absorbents packed in pulses and mini-columns to extract and recover EY dye was attained by 98.94%. The column could efficiently remove different dyes from real industrial effluents, and hence the sol-gel/PUF is a good competitor for commercial applications. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements. Therefore, this study has provided a convenient pathway for the preparation of compressible and reusable sponge materials from renewable biomass for efficient removal of EY from the water environment.

In Vivo Detection of Changes Related to Cortical Columnar Organization and Neuroinflammation Across the AD Continuum.

BACKGROUND: Alzheimer's disease (AD) neuropathology reveals progressive microstructural alterations of cortical architecture. Recent studies reported intriguing biphasic trajectories of cortical structural changes in the early stages of Alzheimer's disease (AD), comprising decreased mean diffusivity (MD) and increased cortical thickness in cognitively normal amyloid-positive individuals, ahead of increases and decreases, respectively, in subsequent disease stages. OBJECTIVE: To better understand the cytoarchitectural correlates of these observations, we assessed novel cortical diffusion tensor imaging (DTI) metrics that are correlated with disruption of cortical minicolumns and protein deposition. DESIGN: Cross-sectional and longitudinal analysis of whole brain and temporal lobe cortical diffusivity measures. Investigation of associations between baseline cortical diffusivity values and 24-month longitudinal structural-MRI changes. Investigations of the relationships between cortical diffusivity measures and biomarkers of neuroinflammation. SETTING: Alzheimer's Disease Neuroimaging Initiative (ADNI). PARTICIPANTS: Twenty-four amyloid-negative controls (CN-), 28 amyloid-positive controls (CN+), 46 amyloid-positive subjects with mild cognitive impairment (MCI+) and 22 amyloid-positive subjects with AD were included. MEASUREMENTS: 3DT1 and DTI scans at baseline and approximately 24-month follow-up were used to calculate cortical MD and three novel cortical diffusivity measures: the angle between the radial minicolumnar axis and the principal diffusion direction (AngleR); the diffusion components perpendicular to the minicolumns (PerpPD+), and the principal diffusion component parallel with the minicolumns (ParlPD). Cortical macrostructural measurements (cortical volume fraction and cortical thickness), were used to test the hypothesis that baseline cortical diffusivity values can predict change in structural MRI outcomes over approximately 24 months. CSF soluble TREM2 and progranulin (PGRN) concentrations were used to investigate associations with microglial activity and potentially other aspects of neuroinflammation. RESULTS: Cortical diffusivity metrics revealed a dependence on disease stage, with AngleR and PerpPD+ displaying biphasic relationships and ParlPD a monotonic relationship with clinical severity. The novel metrics were able to differentiate between Amyloid+ and Amyloid- controls (AngleR) and to differentiate among disease stages along the AD continuum (PerpPD+). Linear regression revealed significant associations between baseline cortical diffusivity values and subsequent 24-month longitudinal structural-MRI changes. AngleR values were significantly associated with CSF sTREM2 and PGRN concentrations. CONCLUSIONS: Cortical diffusivity parameters reflecting minicolumnar organization and neuroinflammation may provide a sensitive and biologically interpretable measurement of cortex quality and microstructure across the AD continuum.

Intracortical diffusion tensor imaging signature of microstructural changes in frontotemporal lobar degeneration.

BACKGROUND: Frontotemporal lobar degeneration (FTLD) is a neuropathological construct with multiple clinical presentations, including the behavioural variant of frontotemporal dementia (bvFTD), primary progressive aphasia-both non-fluent variant (nfvPPA) and semantic variant (svPPA)-progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS), characterised by the deposition of abnormal tau protein in the brain. A major challenge for treating FTLD is early diagnosis and accurate discrimination among different syndromes. The main goal here was to investigate the cortical architecture of FTLD syndromes using cortical diffusion tensor imaging (DTI) analysis and to test its power to discriminate between different clinical presentations. METHODS: A total of 271 individuals were included in the study: 87 healthy subjects (HS), 31 semantic variant primary progressive aphasia (svPPA), 37 behavioural variant (bvFTD), 30 non-fluent/agrammatic variant primary progressive aphasia (nfvPPA), 47 PSP Richardson's syndrome (PSP-RS) and 39 CBS cases. 3T MRI T1-weighted images and DTI scans were analysed to extract three cortical DTI derived measures (AngleR, PerpPD and ParlPD) and mean diffusivity (MD), as well as standard volumetric measurements. Whole brain and regional data were extracted. Linear discriminant analysis was used to assess the group discrimination capability of volumetric and DTI measures to differentiate the FTLD syndromes. In addition, in order to further investigate differential diagnosis in CBS and PSP-RS, a subgroup of subjects with autopsy confirmation in the training cohort was used to select features which were then tested in the test cohort. Three different challenges were explored: a binary classification (controls vs all patients), a multiclass classification (HS vs bvFTD vs svPPA vs nfvPPA vs CBS vs PSP-RS) and an additional binary classification to differentiate CBS and PSP-RS using features selected in an autopsy confirmed subcohort. RESULTS: Linear discriminant analysis revealed that PerpPD was the best feature to distinguish between controls and all patients (ACC 86%). PerpPD regional values were able to classify correctly the different FTLD syndromes with an accuracy of 85.6%. The PerpPD and volumetric values selected to differentiate CBS and PSP-RS patients showed a classification accuracy of 85.2%. CONCLUSIONS: (I) PerpPD achieved the highest classification power for differentiating healthy controls and FTLD syndromes and FTLD syndromes among themselves. (II) PerpPD regional values could provide an additional marker to differentiate FTD, PSP-RS and CBS.

Spatio-Temporal Sequential Memory Model With Mini-Column Neural Network.

Memory is an intricate process involving various faculties of the brain and is a central component in human cognition. However, the exact mechanism that brings about memory in our brain remains elusive and the performance of the existing memory models is not satisfactory. To overcome these problems, this paper puts forward a brain-inspired spatio-temporal sequential memory model based on spiking neural networks (SNNs). Inspired by the structure of the neocortex, the proposed model is structured by many mini-columns composed of biological spiking neurons. Each mini-column represents one memory item, and the firing of different spiking neurons in the mini-column depends on the context of the previous inputs. The Spike-Timing-Dependant Plasticity (STDP) is used to update the connections between excitatory neurons and formulates association between two memory items. In addition, the inhibitory neurons are employed to prevent incorrect prediction, which contributes to improving the retrieval accuracy. Experimental results demonstrate that the proposed model can effectively store a huge number of data and accurately retrieve them when sufficient context is provided. This work not only provides a new memory model but also suggests how memory could be formulated with excitatory/inhibitory neurons, spike-based encoding, and mini-column structure.

Detection of Alzheimer's Disease using cortical diffusion tensor imaging.

The aim of this research was to test a novel in-vivo brain MRI analysis method that could be used in clinical cohorts to investigate cortical architecture changes in patients with Alzheimer's Disease (AD). Three cohorts of patients with probable AD and healthy volunteers were used to assess the results of the method. The first group was used as the "Discovery" cohort, the second as the "Test" cohort and the last "ATN" (Amyloid, Tau, Neurodegeneration) cohort was used to test the method in an ADNI 3 cohort, comparing to amyloid and Tau PET. The method can detect altered quality of cortical grey matter in AD patients, providing an additional tool to assess AD, distinguishing between these and healthy controls with an accuracy range between good and excellent. These new measurements could be used within the "ATN" framework as an index of cortical microstructure quality and a marker of Neurodegeneration. Further development may aid diagnosis, patient selection, and quantification of the "Neurodegeneration" component in response to therapies in clinical trials.

Cortical diffusivity investigation in posterior cortical atrophy and typical Alzheimer's disease.

OBJECTIVES: To investigate the global cortical and regional quantitative features of cortical neural architecture in the brains of patients with posterior cortical atrophy (PCA) and typical Alzheimer's disease (tAD) compared with elderly healthy controls (HC). METHODS: A novel diffusion MRI method, that has been shown to correlate with minicolumnar organization changes in the cerebral cortex, was used as a surrogate of neuropathological changes in dementia. A cohort of 15 PCA patients, 23 tAD and 22 healthy elderly controls (HC) were enrolled to investigate the changes in cortical diffusivity among groups. For each subject, 3 T MRI T1-weighted images and diffusion tensor imaging (DTI) scans were analysed to extract novel cortical DTI derived measures (AngleR, PerpPD and ParlPD). Receiver operating characteristics (ROC) curve analysis and the area under the curve (AUC) were used to assess the group discrimination capability of the method. RESULTS: The results showed that the global cortical DTI derived measures were able to detect differences, in both PCA and tAD patients compared to healthy controls. The AngleR was the best measure to discriminate HC from tAD (AUC = 0.922), while PerpPD was the best measure to discriminate HC from PCA (AUC = 0.961). Finally, the best global measure to differentiate the two patient groups was ParlPD (AUC = 0.771). The comparison between PCA and tAD patients revealed a different pattern of damage within the AD spectrum and the regional comparisons identified significant differences in key regions including parietal and temporal lobe cortical areas. The best AUCs were shown by PerpPD right lingual cortex (AUC = 0.856), PerpPD right superior parietal cortex (AUC = 0.842) and ParlPD right lateral occipital cortex (AUC = 0.826). CONCLUSIONS: Diagnostic group differences were found, suggesting that the new cortical DTI analysis method may be useful to investigate cortical changes in dementia, providing better characterization of neurodegeneration, and potentially aiding differential diagnosis and prognostic accuracy.

[Pesticide Analysis in Agricultural Products by GC-MS/MS Using STQ Method].

As a method to detect pesticide residues in agricultural products, we evaluated the pretreatment of agricultural product samples by the solid-phase extracton technique with QuEChERS (STQ) method followed by GC-MS/MS with large-volume injection using a stomach-type glass-lined injector. This method satisfied the target criteria of recovery (70-120%) and the standard deviation of repeatability (RSD<25%) in 238-282 pesticides found in six types of agricultural products.

Determination of Encapsulation Efficiency of Novel Solid Lipid Nanoparticles Containing Oleic Acid-CAT3 Conjugates by Mini-Column Centrifugation Method / 中国药学杂志

OBJECTIVE: To establish a mini-column centrifugation method to determine the encapsulation efficiency (EE) of novel solid lipid nanoparticles containing oleic acid-CAT3 conjugates (OA-CAT3-SLN) and normal CAT3 SLN (CAT3-SLN). METHODS: Sephadex G-50 mini-columns were used to separate the encapsulated drug and free drug in the solid lipid nanoparticles (SLN) with the help of centrifugation. The boundary point of the elution between the encapsulated drug and free drug was established by the elution curve. The encapsulated drug in the SLN was eluted with 1 mL water for three times. Then 2 mL of ethanol was used to elute the separated free drug for three times. The eluted CAT3 was quantified by the verified HPLC-UV method and used to calculate the EE. The method was verified with the recovery and repeatability test. Finally, the EE of three batches of OA-CAT3-SLN and CAT3-SLN were determined. RESULTS: The mini-column centrifugation method could effectively separate the free drug from the encapsulated drug in SLN. The column recovery was (99.64±1.97)% (n=9), and the result of EE repeatability test of OA-CAT3-SLN was (83.71±0.70)% (n=5). The EE of OA-CAT3-SLN and CAT3-SLN were (86.26±2.65)% and (72.22±4.52)%, respectively (n=3). CONCLUSION: The established separation method is simple and reliable, with high recovery and good repeatability, and can distinguish different preparation processes.

[Evaluation of an Analytical Method Using GC-MS/MS and a 3-Layer Solid Phase Extraction Mini-Column for Pesticide Residues in Agricultural Products].

We developed a simple rapid analysis of multi-pesticide residues in agricultural products. In this study, we attempted to simplify the purification process, and reduce the amount and type of solvent used. The test solution was prepared by clean-up, a 0.5 mL aliquot of QuEChERS extract solution of agricultural products using a 3-layer solid-phase (C18/SAX/PSA) extraction mini-column, and the test solution was subjected to GC-MS/MS analysis, modified with a large volume injection and a stomach-type glass-lined injector. This method met the acceptability criteria of recovery (70-120%) and standard deviation of repeatability (RSD<25%) in 241-331 pesticides in 8 types of agricultural products.

Pathoarchitectonics of the cerebral cortex in chorea-acanthocytosis and Huntington's disease.

AIMS: Quantitative estimation of cortical neurone loss in cases with chorea-acanthocytosis (ChAc) and its impact on laminar composition. METHODS: We used unbiased stereological tools to estimate the degree of cortical pathology in serial gallocyanin-stained brain sections through the complete hemispheres of three subjects with genetically verified ChAc and a range of disease durations. We compared these results with our previous data of five Huntington's disease (HD) and five control cases. Pathoarchitectonic changes were exemplarily documented in TE1 of a 61-year-old female HD-, a 60-year-old female control case, and ChAc3. RESULTS: Macroscopically, the cortical volume of our ChAc cases (ChAc1-3) remained close to normal. However, the average number of neurones was reduced by 46% in ChAc and by 33% in HD (P = 0.03 for ChAc & HD vs. controls; P = 0.64 for ChAc vs. HD). Terminal HD cases featured selective laminar neurone loss with pallor of layers III, V and VIa, a high density of small, pale, closely packed radial fibres in deep cortical layers VI and V, shrinkage, and chromophilia of subcortical white matter. In ChAc, pronounced diffuse astrogliosis blurred the laminar borders, thus masking the complete and partial loss of pyramidal cells in layer IIIc and of neurones in layers III, V and VI. CONCLUSION: ChAc is a neurodegenerative disease with distinct cortical neurodegeneration. The hypertrophy of the peripheral neuropil space of minicolumns with coarse vertical striation was characteristic of ChAc. The role of astroglia in the pathogenesis of this disorder remains to be elucidated.

Zwitterion-functionalized polymer microspheres as a sorbent for solid phase extraction of trace levels of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) prior to their determination by ICP-MS.

This paper describes the preparation of zwitterion-functionalized polymer microspheres (ZPMs) and their application to simultaneous enrichment of V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) from environmental water samples. The ZPMs were prepared by emulsion copolymerization of ethyl methacrylate, 2-diethylaminoethyl methacrylate and triethylene glycol dimethyl acrylate followed by modification with 1,3-propanesultone. The components were analyzed by elemental analyses as well as Fourier transform infrared spectroscopy, and the structures were characterized by scanning electron microscopy and transmission electron microscopy. The ZPMs were packed into a mini-column for on-line solid-phase extraction (SPE) of the above metal ions. Following extraction with 40 mM NH4NO3 and 0.5 M HNO3 solution, the ions were quantified by ICP-MS. Under the optimized conditions, the enrichment factors (from a 40 mL sample) are up to 60 for the ions V(V), As(III), Sb(III) and Hg(II), and 55 for Cr(III) and Sn(IV). The detection limits are 1.2, 3.4, 1.0, 3.7, 2.1 and 1.6 ng L-1 for V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II), respectively, and the relative standard deviations (RSDs) are below 5.2%. The feasibility and accuracy of the method were validated by successfully analyzing six certified reference materials as well as lake, well and river waters. Graphical abstract Zwitterion-functionalized polymer microspheres (ZPMs) were prepared and packed into a mini-column for on-line solid-phase extraction (SPE) via pump 1. Then V(V), Cr(III), As(III), Sn(IV), Sb(III) and Hg(II) ions in environmental waters were eluted and submitted to ICP-MS via pump 2.

Mini-column assay for rapid detection of malachite green in fish.

A simple, rapid and economical mini-column method for detecting malachite green (MG) residue in fish was developed. The method used a column with 2mm ID that was tightly packed with silica gel followed by alumina. Detection of MG was performed by viewing the developed mini-column at visible light by naked eye; where MG was seen as compact green band at the confluence of the silica gel layer with alumina layer. The limit of detection of the assay was 2ng which conform the minimum required performance limit (MRPL). Evaluation utility of the method indicated that all blank and spiked samples at levels below MRPL were assessed as accepted. The intensity of the green band increased whenever MG level in the extract increased; indicated that suggested mini-column technique could be used for semi-quantitative determination of MG in fish samples. The method can be used to select the questionable samples.

Using on-line solid phase extraction for in vivo speciation of diffusible ferrous and ferric iron in living rat brain extracellular fluid.

Exploration of brain extracellular non-protein-bound/diffusible iron species remains a critically important issue in investigations of free radical biology and neurodegenerative diseases. In this study, a facile sample pretreatment scheme, involving poly(vinyl chloride)-metal ion interactions as a selective extraction procedure, was optimized in conjunction with microdialysis (MD) sampling and inductively coupled plasma mass spectrometry (ICP-MS) in cool-plasma mode for in vivo online monitoring of rat brain extracellular Fe(II) and Fe(III) species. Optimization of the system provided detection limits in the range 0.9-6.9 µg Fe L-1, based on a 12-µL microdialysate, for the tested iron species; relative standard deviations of the signal intensities during 7.8 h of continuous measurement were less than 9.4%-sufficient to determine the basal concentrations of rat brain extracellular Fe(II) and Fe(III) species and to describe their dynamic actions. The method's applicability was verified through (i) spike analyses of offline-collected rat brain microdialysates, (ii) determination of the basal Fe(II) and Fe(III) concentrations of living rat brain extracellular fluids, and (iii) monitoring of the dynamic changes in the Fe(II) and Fe(III) concentrations in response to perfusion of a high-K+ medium. This proposed sample pretreatment scheme, based on polymer-metal ion interactions and hyphenation to an MD sampling device and an ICP-MS system, appears to have great practicality for the online monitoring of rat brain extracellular diffusible iron species.

Titanium dioxide solid phase for inorganic species adsorption and determination: the case of arsenic.

We have evaluated a new titanium dioxide (Adsorbsia As600) for the adsorption of both inorganic As (V) and As (III) species. In order to characterize the sorbent, batch experiments were undertaken to determine the capacities of As (III) and As (V) at pH 7.3, which were found to be 0.21 and 0.14 mmol g-1, respectively. Elution of adsorbed species was only possible using basic solutions, and arsenic desorbed under batch conditions was 50 % when 60 mg of loaded titanium dioxide was treated with 0.5 M NaOH solution. Moreover, its use as a sorbent for solid-phase extraction and preconcentration of arsenic species from well waters has been investigated, without any previous pretreatment of the sample. Solid-phase extraction was implemented by packing several minicolumns with Adsorbsia As600. The method has been validated showing good accuracy and precision. Acceptable recoveries were obtained when spiked waters at 100-200 µg L-1 were measured. The presence of major anions commonly found in waters did not affect arsenic adsoption, and only silicate at 100 mg L-1 level severely competed with arsenic species to bind to the material. Finally, the measured concentrations in water samples containing arsenic from the Pyrinees (Catalonia, Spain) showed good agreement with the ICP-MS results.

"Subpial Fan Cell" - A Class of Calretinin Neuron in Layer 1 of Adult Monkey Prefrontal Cortex.

Layer 1 of the cortex contains populations of neurochemically distinct neurons and afferent fibers which markedly affect neural activity in the apical dendritic tufts of pyramidal cells. Understanding the causal mechanisms requires knowledge of the cellular architecture and synaptic organization of layer 1. This study has identified eight morphological classes of calretinin immunopositive (CRet+) neurons (including Cajal-Retzius cells) in layer 1 of the prefrontal cortex (PFC) in adult monkey (Macaca fasicularis), with a distinct class - termed "subpial fan (SPF) cell" - described in detail. SPF cells were rare horizontal unipolar CRet+ cells located directly beneath the pia with a single thick primary dendrite that branched into a characteristic fan-like dendritic tree tangential to the pial surface. Dendrites had spines, filamentous processes and thorny branchlets. SPF cells lay millimeters apart with intralaminar axons that ramified widely in upper layer 1. Such cells were GABA immunonegative (-) and occurred in areas beyond PFC. Interspersed amidst SPF cells displaying normal structural integrity were degenerating CRet+ neurons (including SPF cells) and clumps of lipofuscin-rich cellular debris. The number of degenerating SPF cells increased during adulthood. Ultrastructural analyses indicated SPF cell somata received asymmetric (A - presumed excitatory) and symmetric (S - presumed inhibitory) synaptic contacts. Proximal dendritic shafts received mainly S-type and distal shafts mostly A-type input. All dendritic thorns and most dendritic spines received both synapse types. The tangential areal density of SPF cell axonal varicosities varied radially from parent somata - with dense clusters in more distal zones. All boutons formed A-type contacts with CRet- structures. The main post-synaptic targets were dendritic shafts (67%; mostly spine-bearing) and dendritic spines (24%). SPF-SPF cell innervation was not observed. Morphometry of SPF cells indicated a unique class of CRet+/GABA- neuron in adult monkey PFC - possibly a subtype of persisting Cajal-Retzius cell. The distribution and connectivity of SPF cells suggest they act as integrative hubs in upper layer 1 during postnatal maturation. The main synaptic output of SPF cells likely provides a transminicolumnar excitatory influence across swathes of apical dendritic tufts - thus affecting information processing in discrete patches of layer 1 in adult monkey PFC.

Autism spectrum disorders: linking neuropathological findings to treatment with transcranial magnetic stimulation.

UNLABELLED: Postmortem studies in autism spectrum disorder (ASD) individuals indicate the presence of abnormalities within the peripheral neuropil space (PNS) of cortical minicolumns. The geometrical orientation of inhibitory elements within the PNS suggests using repetitive transcranial magnetic stimulation (rTMS) to up-regulate their activity. Several rTMS trials in ASD have shown marked improvements in motor symptomatology, attention and perceptual binding. CONCLUSION: rTMS is the first therapeutic attempt at ASD aimed at correcting some of its core pathology.

Mini-column screening assay for tetracyclines in chicken.

A simple, rapid, reliable and economical mini-column (MC) method for the detection of tetracyclines (TCs) residues in chicken meat was developed. The method employs a commonly available Pasteur pipette which is tightly packed with silica gel and anhydrous sodium sulfate. Clean-up and detection of illegal levels can be achieved on the same column. Viewing the developed MC under an ultraviolet lamp revealed that TCs can be detected as a compact golden yellow fluorescent band at the junction between the anhydrous sodium sulfate and silica gel layers. Comparing the yellow band of control extracts with those fortified (100 ng ml(-1)) showed no overlap between analyte and impurities. The limit of detection (LOD) of the MC assay was 1 ng, indicating that the chicken sample containing 10 µg TCs kg(-1) sample could be easily detected. Moreover, the intensity of the yellow band increased whenever TCs levels in the extract increased. Evaluation utility of the method with blind samples as controls or samples fortified with total TCs at various levels indicated that the total blank and spiked samples at levels equal or below the permissible limits were assessed as accepted. The method can provide an alternative to microbial screening assays and could be used as an effective pre-screening technique in public health laboratories.

The cortical microstructural basis of lateralized cognition: a review.

The presence of asymmetry in the human cerebral hemispheres is detectable at both the macroscopic and microscopic scales. The horizontal expansion of cortical surface during development (within individual brains), and across evolutionary time (between species), is largely due to the proliferation and spacing of the microscopic vertical columns of cells that form the cortex. In the asymmetric planum temporale (PT), minicolumn width asymmetry is associated with surface area asymmetry. Although the human minicolumn asymmetry is not large, it is estimated to account for a surface area asymmetry of approximately 9% of the region's size. Critically, this asymmetry of minicolumns is absent in the equivalent areas of the brains of other apes. The left-hemisphere dominance for processing speech is thought to depend, partly, on a bias for higher resolution processing across widely spaced minicolumns with less overlapping dendritic fields, whereas dense minicolumn spacing in the right hemisphere is associated with more overlapping, lower resolution, holistic processing. This concept refines the simple notion that a larger brain area is associated with dominance for a function and offers an alternative explanation associated with "processing type." This account is mechanistic in the sense that it offers a mechanism whereby asymmetrical components of structure are related to specific functional biases yielding testable predictions, rather than the generalization that "bigger is better" for any given function. Face processing provides a test case - it is the opposite of language, being dominant in the right hemisphere. Consistent with the bias for holistic, configural processing of faces, the minicolumns in the right-hemisphere fusiform gyrus are thinner than in the left hemisphere, which is associated with featural processing. Again, this asymmetry is not found in chimpanzees. The difference between hemispheres may also be seen in terms of processing speed, facilitated by asymmetric myelination of white matter tracts (Anderson et al., 1999 found that axons of the left posterior superior temporal lobe were more thickly myelinated). By cross-referencing the differences between the active fields of the two hemispheres, via tracts such as the corpus callosum, the relationship of local features to global features may be encoded. The emergent hierarchy of features within features is a recursive structure that may functionally contribute to generativity - the ability to perceive and express layers of structure and their relations to each other. The inference is that recursive generativity, an essential component of language, reflects an interaction between processing biases that may be traceable in the microstructure of the cerebral cortex. Minicolumn organization in the PT and the prefrontal cortex has been found to correlate with cognitive scores in humans. Altered minicolumn organization is also observed in neuropsychiatric disorders including autism and schizophrenia. Indeed, altered interhemispheric connections correlated with minicolumn asymmetry in schizophrenia may relate to language-processing anomalies that occur in the disorder. Schizophrenia is associated with over-interpretation of word meaning at the semantic level and over-interpretation of relevance at the level of pragmatic competence, whereas autism is associated with overly literal interpretation of word meaning and under-interpretation of social relevance at the pragmatic level. Both appear to emerge from a disruption of the ability to interpret layers of meaning and their relations to each other. This may be a consequence of disequilibrium in the processing of local and global features related to disorganization of minicolumnar units of processing.

Prefrontal cortical minicolumn: from executive control to disrupted cognitive processing.

The prefrontal cortex of the primate brain has a modular architecture based on the aggregation of neurons in minicolumnar arrangements having afferent and efferent connections distributed across many brain regions to represent, select and/or maintain behavioural goals and executive commands. Prefrontal cortical microcircuits are assumed to play a key role in the perception to action cycle that integrates relevant information about environment, and then selects and enacts behavioural responses. Thus, neurons within the interlaminar microcircuits participate in various functional states requiring the integration of signals across cortical layers and the selection of executive variables. Recent research suggests that executive abilities emerge from cortico-cortical interactions between interlaminar prefrontal cortical microcircuits, whereas their disruption is involved in a broad spectrum of neurologic and psychiatric disorders such as autism, schizophrenia, Alzheimer's and drug addiction. The focus of this review is on the structural, functional and pathological approaches involving cortical minicolumns. Based on recent technological progress it has been demonstrated that microstimulation of infragranular cortical layers with patterns of microcurrents derived from supragranular layers led to an increase in cognitive performance. This suggests that interlaminar prefrontal cortical microcircuits are playing a causal role in improving cognitive performance. An important reason for the new interest in cortical modularity comes from both the impressive progress in understanding anatomical, physiological and pathological facets of cortical microcircuits and the promise of neural prosthetics for patients with neurological and psychiatric disorders.