Functional anatomy of human eyeblink conditioning determined with regional cerebral glucose metabolism and positron-emission tomography.

Relative cerebral glucose metabolism was examined with positron-emission tomography (PET) as a measure of neuronal activation during performance of the classically conditioned eyeblink response in 12 young adult subjects. Each subject received three sessions: (i) a control session with PET scan in which unpaired presentations of the tone conditioned stimulus and corneal airpuff unconditioned stimulus were administered, (ii) a paired training session to allow associative learning to occur, and (iii) a paired test session with PET scan. Brain regions exhibiting learning-related activation were identified as those areas that showed significant differences in glucose metabolism between the unpaired control condition and well-trained state in the 9 subjects who met the learning criterion. Areas showing significant activation included bilateral sites in the inferior cerebellar cortex/deep nuclei, anterior cerebellar vermis, contralateral cerebellar cortex and pontine tegmentum, ipsilateral inferior thalamus/red nucleus, ipsilateral hippocampal formation, ipsilateral lateral temporal cortex, and bilateral ventral striatum. Among all subjects, including those who did not meet the learning criterion, metabolic changes in ipsilateral cerebellar nuclei, bilateral cerebellar cortex, anterior vermis, contralateral pontine tegmentum, ipsilateral hippocampal formation, and bilateral striatum correlated with degree of learning. The localization to cerebellum and its associated brainstem circuitry is consistent with neurobiological studies in the rabbit model of eyeblink classical conditioning and neuropsychological studies in brain-damaged humans. In addition, these data support a role for the hippocampus in conditioning and suggest that the ventral striatum may also be involved.

Three-dimensional functional magnetic resonance imaging of human brain on a clinical 1.5-T scanner.

Functional magnetic resonance imaging (fMRI) is a tool for mapping brain function that utilizes neuronal activity-induced changes in blood oxygenation. An efficient three-dimensional fMRI method is presented for imaging brain activity on conventional, widely available, 1.5-T scanners, without additional hardware. This approach uses large magnetic susceptibility weighting based on the echo-shifting principle combined with multiple gradient echoes per excitation. Motor stimulation, induced by self-paced finger tapping, reliably produced significant signal increase in the hand region of the contralateral primary motor cortex in every subject tested.

Parameters affecting conscious versus unconscious visual discrimination with damage to the visual cortex (V1).

When the visual (striate) cortex (V1) is damaged in human subjects, cortical blindness results in the contralateral visual half field. Nevertheless, under some experimental conditions, subjects demonstrate a capacity to make visual discriminations in the blind hemifield (blindsight), even though they have no phenomenal experience of seeing. This capacity must, therefore, be mediated by parallel projections to other brain areas. It is also the case that some subjects have conscious residual vision in response to fast moving stimuli or sudden changes in light flux level presented to the blind hemifield, characterized by a contentless kind of awareness, a feeling of something happening, albeit not normal seeing. The relationship between these two modes of discrimination has never been studied systematically. We examine, in the same experiment, both the unconscious discrimination and the conscious visual awareness of moving stimuli in a subject with unilateral damage to V1. The results demonstrate an excellent capacity to discriminate motion direction and orientation in the absence of acknowledged perceptual awareness. Discrimination of the stimulus parameters for acknowledged awareness apparently follows a different functional relationship with respect to stimulus speed, displacement, and stimulus contrast. As performance in the two modes can be quantitatively matched, the findings suggest that it should be possible to image brain activity and to identify the active areas involved in the same subject performing the same discrimination task, both with and without conscious awareness, and hence to determine whether any structures contribute uniquely to conscious perception.

Age-related learning deficits in transgenic mice expressing the 751-amino acid isoform of human beta-amyloid precursor protein.

The beta-amyloid precursor protein (beta-APP), from which the beta-A4 peptide is derived, is considered to be central to the pathogenesis of Alzheimer disease (AD). Transgenic mice expressing the 751-amino acid isoform of human beta-APP (beta-APP751) have been shown to develop early AD-like histopathology with diffuse deposits of beta-A4 and aberrant tau protein expression in the brain, particularly in the hippocampus, cortex, and amygdala. We now report that beta-APP751 transgenic mice exhibit age-dependent deficits in spatial learning in a water-maze task and in spontaneous alternation in a Y maze. These deficits were mild or absent in 6-month-old transgenic mice but were severe in 12-month-old transgenic mice compared to age-matched wild-type control mice. No other behavioral abnormalities were observed. These mice therefore model the progressive learning and memory impairment that is a cardinal feature of AD. These results provide evidence for a relationship between abnormal expression of beta-APP and cognitive impairments.

Characterization of subtype-specific antibodies to the human D5 dopamine receptor: studies in primate brain and transfected mammalian cells.

To achieve a better understanding of how D5 dopamine receptors mediate the actions of dopamine in brain, we have developed antibodies specific for the D5 receptor. D5 antibodies reacted with recombinant baculovirus-infected Sf9 cells expressing the D5 receptor but not with the D1 receptor or a variety of other catecholaminergic and muscarinic receptors. Epitope-tagged D5 receptors expressed in mammalian cells were reactive with both D5 antibodies and an epitope-specific probe. A mixture of N-linked glycosylated polypeptides and higher molecular-mass species was detected on immunoblots of membrane fractions of D5-transfected cells and also of primate brain. D5 receptor antibodies intensely labeled pyramidal neurons in the prefrontal cortex, whereas spiny medium-sized neurons and aspiny large interneurons of the caudate nucleus were relatively lightly labeled. Antibodies to the D5 dopamine receptor should prove important in experimentally determining specific roles for the D5 and D1 receptors in cortical processes and diseases.

Pleasant sweeping grooming touch in rhesus monkey: effects on autonomic nervous system and its codification in posterior insular and secondary somatosensory cortex

Il tatto assume un'importanza fondamentale nella vita quotidiana, in quanto ci permette di discriminare le caratteristiche fisiche di un oggetto specifico, di identificarlo e di eventualmente integrare le suddette informazioni tattili con informazioni provenienti da altri canali sensoriali. Questa è la componente sensoriale-discriminativa del tatto. Tuttavia quotidianamente il tatto assume un ruolo fondamentale durante le diverse interazioni sociali, positive, come quando abbracciamo o accarezziamo una persona con cui abbiamo un rapporto affettivo e negative, per esempio quando allontaniamo una persona estranea dal nostro spazio peri-personale. Questa componente è la cosiddetta dimensione affettiva-motivazionale, la quale determina la codifica della valenza emotiva che l'interazione assume. Questa componente ci permette di creare, mantenere o distruggere i legami sociali in relazione al significato che il tocco assume durante l'interazione. Se per esempio riceviamo una carezza da un familiare, questa verrà percepita come piacevole e assumerà un significato affiliativo. Questo tipo di tocco è comunente definito come Tocco Sociale (Social Touch). Gli aspetti discriminativi del tatto sono stati ben caratterizzati, in quanto storicamente, il ruolo del tatto è stato considerato quello di discriminare le caratteristiche di ciò che viene toccato, mentre gli aspetti affettivi sono stati solo recentemente indagati considerando la loro importanza nelle interazioni sociali. Il tocco statico responsabile dell'aspetto discriminante attiva a livello della pelle le grandi fibre mieliniche (Aβ), modulando a livello del sistema nervoso centrale le cortecce sensoriali, sia primarie che secondarie. Questo permette la codifica a livello del sistema nervoso centrale delle caratteristiche fisiche oggettive degli oggetti toccati. Studi riguardanti le caratteristiche del tocco affiliativo sociale hanno messo in evidenza che suddetta stimolazione tattile 1) è un particolare tocco dinamico che avviene sul lato peloso delle pelle con una velocità di 1-10 cm/sec; 2) attiva le fibre amieliniche (fibre CT o C-LTMRs); 3) induce positivi effetti autonomici, ad esempio la diminuzione della frequenza cardiaca e l'aumento della variabilità della frequenza cardiaca; e 4) determina la modulazione di regioni cerebrali coinvolte nella codifica del significato affiliativo dello stimolo sensoriale periferico, in particolare la corteccia insulare. Il senso del tatto, con le sue due dimensioni discriminativa e affiliativa, è quotidianamente usato non solo negli esseri umani, ma anche tra i primati non umani. Infatti, tutti i primati non umani utilizzano la componente discriminativa del tatto per identificare gli oggetti e il cibo e l'aspetto emotivo durante le interazioni sociali, sia negative come durante un combattimento, che positive, come durante i comportamenti affiliativi tra cui il grooming. I meccanismi di codifica della componente discriminativa dei primati non umani sono simili a quelli umani. Tuttavia, si conosce ben poco dei meccanismi alla base della codifica del tocco piacevole affiliativo. Pur essendo ben noto che i meccanorecettori amilienici C-LTMRs sono presenti anche sul lato peloso della pelle dei primati non umani, attualmente non ci sono studi riguardanti la correlazione tra il tocco piacevole e la loro modulazione, come invece è stato ampiamente dimostrato nell'uomo. Recentemente è stato ipotizzato (Dunbar, 2010) il ruolo delle fibre C-LTMRs durante il grooming, in particolare durante il cosiddetto swepping. Il grooming è costituito da due azioni motorie, lo sweeping e il picking che vengono eseguite in modo ritmico. Durante lo sweeping la scimmia agente muove il pelo della scimmia ricevente con un movimento a mano aperta, per poter vedere il preciso punto della pelle dove eseguire il picking, ovvero dove prendere la pelle a livello della radice del pelo con le unghie dell'indice e del pollice e tirare per rimuovere parassiti o uova di parassiti e ciò che è rimasto incastrato nel pelo. Oltre il noto ruolo igenico, il grooming sembra avere anche una importante funzione sociale affiliativa. Come la carezza nella società umana, cosi il grooming tra i primati non umani è considerato un comportamento. Secondo l'ipotesi di Dunbar l'attivazione delle C-LTMRs avverrebbe durante lo sweeping e questo porta a supporre che lo sweeping, come la carezza umana, costituisca una componente affiliativa del grooming, determinando quindi a contribuire alla sua codifica come comportamento sociale. Fino ad ora non vi è però alcuna prova diretta a sostegno di questa ipotesi. In particolare, 1) la velocità cui viene eseguito lo sweeping è compatibile con la velocità di attivazione delle fibre CT nell'uomo e quindi con la velocità tipica della carezza piacevole di carattere sociale affiliativo (1-10 cm/sec)?; 2) lo sweeping induce la stessa modulazione del sistema nervoso autonomo in direzione della modulazione del sistema vagale, come il tocco piacevole nell'uomo, attraverso l'attivazione delle fibre CT?; 3) lo sweeping modula la corteccia insulare, cosi come il tocco piacevole viene codificato come affiliativo nell'uomo mediante le proiezioni delle fibre CT a livello dell'insula posteriore? Lo scopo del presente lavoro è quella di testare l'ipotesi di Dunbar sopra citata, cercando quindi di rispondere alle suddette domande. Le risposte potrebbero consentire di ipotizzare la somiglianza tra lo sweeping, caratteristico del comportamento affiliativo di grooming tra i primati non umani e la carezza. In particolare, abbiamo eseguito 4 studi pilota. Nello Studio 1 abbiamo valutato la velocità con cui viene eseguito lo sweeping tra scimmie Rhesus, mediante una analisi cinematica di video registrati tra un gruppo di scimmie Rhesus. Negli Studi 2 e 3 abbiamo valutato gli effetti sul sistema nervoso autonomo dello sweeping eseguito dallo sperimentatore su una scimmia Rhesus di sesso maschile in una tipica situazione sperimentale. La stimolazione tattile è stata eseguita a diverse velocità, in accordo con i risultati dello Studio 1 e degli studi umani che hanno dimostrato la velocità ottimale e non ottimale per l'attivazione delle C-LTMRs. In particolare, nello Studio 2 abbiamo misurato la frequenza cardiaca e la variabilità di questa, come indice della modulatione vagale, mentre nello Studio 3 abbiamo valutato gli effetti dello sweeping sul sistema nervoso autonomo in termini di variazioni di temperatura del corpo, nello specifico a livello del muso della scimmia. Infine, nello Studio 4 abbiamo studiato il ruolo della corteccia somatosensoriale secondaria e insulare nella codifica dello sweeping. A questo scopo abbiamo eseguito registrazioni di singoli neuroni mentre la medesima scimmia soggetto sperimentale dello Studio 2 e 3, riceveva lo sweeping a due velocità, una ottimale per l'attivazione delle C-LTMRs secondo gli studi umani e i risultati dei tre studi sopra citati, ed una non ottimale. I dati preliminari ottenuti, dimostrano che 1) (Studio 1) lo sweeping tra scimmie Rhesus viene eseguito con una velocità media di 9.31 cm/sec, all'interno dell'intervallo di attivazione delle fibre CT nell'uomo; 2) (Studio 2) lo sweeping eseguito dallo sperimentatore sulla schiena di una scimmia Rhesus di sesso maschile in una situazione sperimentale determina una diminuzione della frequenza cardiaca e l'aumento della variabilità della frequenza cardiaca se eseguito alla velocità di 5 e 10 cm/sec. Al contrario, lo sweeping eseguito ad una velocità minore di 1 cm/sec o maggiore di 10 cm/sec, determina l'aumento della frequenza cardiaca e la diminuzione della variabilità di questa, quindi il decremento dell'attivazione del sistema nervoso parasimpatico; 3) (Studio 3) lo sweeping eseguito dallo sperimentatore sulla schiena di una scimmia Rhesus di sesso maschile in una situazione sperimentale determina l'aumento della temperatura corporea a livello del muso della scimmia se eseguito alla velocità di 5-10 cm/sec. Al contrario, lo sweeping eseguito ad una velocità minore di 5 cm/sec o maggiore di 10 cm/sec, determina la diminuzione della temperatura del muso; 4) (Studio 4) la corteccia somatosensoriale secondaria e la corteccia insulare posteriore presentano neuroni selettivamente modulati durante lo sweeping eseguito ad una velocità di 5-13 cm/sec ma non neuroni selettivi per la codifica della velocità dello sweeping minore di 5 cm/sec. Questi risultati supportano l'ipotesi di Dunbar relativa al coinvolgimento delle fibre CT durante lo sweeping. Infatti i dati mettono in luce che lo sweeping viene eseguito con una velocità (9.31 cm/sec), simile a quella di attivazione delle fibre CT nell'uomo (1-10 cm/sec), determina gli stessi effetti fisiologici positivi in termini di frequenza cardiaca (diminuzione) e variabilità della frequenza cardiaca (incremento) e la modulazione delle medesime aree a livello del sistema nervoso centrale (in particolare la corteccia insulare). Inoltre, abbiamo dimostrato per la prima volta che suddetta stimolazione tattile determina l'aumento della temperatura del muso della scimmia. Il presente studio rappresenta la prima prova indiretta dell'ipotesi relativa alla modulazione del sistema delle fibre C-LTMRs durante lo sweeping e quindi della codifica della stimolazione tattile piacevole affiliativa a livello del sistema nervoso centrale ed autonomo, nei primati non umani. I dati preliminari qui presentati evidenziano la somiglianza tra il sistema delle fibre CT dell'uomo e del sistema C-LTMRs nei primati non umano, riguardanti il Social Touch. Nonostante ciò abbiamo riscontrato alcune discrepanze tra i risultati da noi ottenuti e quelli invece ottenuti dagli studi umani. La velocità media dello sweeping è di 9.31 cm / sec, rasente il limite superiore dell’intervallo di velocità che attiva le fibre CT nell'uomo. Inoltre, gli effetti autonomici positivi, in termini di battito cardiaco, variabilità della frequenza cardiaca e temperatura a livello del muso, sono stati evidenziati durante lo sweeping eseguito con una velocità di 5 e 10 cm/sec, quindi al limite superiore dell’intervallo ottimale che attiva le fibre CT nell’uomo. Al contrario, lo sweeping eseguito con una velocità inferiore a 5 cm/sec e superiore a 10 cm/sec determina effetti fisiologici negativo. Infine, la corteccia insula sembra essere selettivamente modulata dallo stimolazione eseguita alla velocità di 5-13 cm/sec, ma non 1-5 cm/sec. Quindi, gli studi sul sistema delle fibre CT nell’uomo hanno dimostrato che la velocità ottimale è 1-10 cm/sec, mentre dai nostri risultati la velocità ottimale sembra essere 5-13 cm / sec. Quindi, nonostante l'omologia tra il sistema delle fibre CT nell'umano deputato alla codifica del tocco piacevole affiliativo ed il sistema delle fibre C-LTMRs nei primati non umani, ulteriori studi saranno necessari per definire con maggiore precisione la velocità ottimale di attivazione delle fibre C-LTMR e per dimostrare direttamente la loro attivazione durante lo sweeping, mediante la misurazione diretta della loro modulazione. Studi in questa direzione potranno confermare l'omologia tra lo sweeping in qualità di tocco affiliativo piacevole tra i primati non umani e la carezza tra gli uomini. Infine, il presente studio potrebbe essere un importante punto di partenza per esplorare il meccanismo evolutivo dietro la trasformazione dello sweeping tra primati non umani, azione utilitaria eseguita durante il grooming, a carezza, gesto puramente affiliativo tra gli uomini.

Role of the monkey ventrolateral prefrontal cortex in the integration of contextual information for the selection and understanding of goal-directed actions

Action selection and organization are very complex processes that need to exploit contextual information and the retrieval of previously memorized information, as well as the integration of these different types of data. On the basis of anatomical connection with premotor and parietal areas involved in action goal coding, and on the data about the literature it seems appropriate to suppose that one of the most candidate involved in the selection of neuronal pools for the selection and organization of intentional actions is the prefrontal cortex. We recorded single ventrolateral prefrontal (VLPF) neurons activity while monkeys performed simple and complex manipulative actions aimed at distinct final goals, by employing a modified and more strictly controlled version of the grasp-to-eat(a food pellet)/grasp-to-place(an object) paradigm used in previous studies on parietal (Fogassi et al., 2005) and premotor neurons (Bonini et al., 2010). With this task we have been able both to evaluate the processing and integration of distinct (visual and auditory) contextual sequentially presented information in order to select the forthcoming action to perform and to examine the possible presence of goal-related activity in this portion of cortex. Moreover, we performed an observation task to clarify the possible contribution of VLPF neurons to the understanding of others’ goal-directed actions. Simple Visuo Motor Task (sVMT). We found four main types of neurons: unimodal sensory-driven, motor-related, unimodal sensory-and-motor, and multisensory neurons. We found a substantial number of VLPF neurons showing both a motor-related discharge and a visual presentation response (sensory-and-motor neurons), with remarkable visuo-motor congruence for the preferred target. Interestingly the discharge of multisensory neurons reflected a behavioural decision independently from the sensory modality of the stimulus allowing the monkey to make it: some encoded a decision to act/refraining from acting (the majority), while others specified one among the four behavioural alternatives. Complex Visuo Motor Task (cVMT). The cVMT was similar to the sVMT, but included a further grasping motor act (grasping a lid in order to remove it, before grasping the target) and was run in two modalities: randomized and in blocks. Substantially, motor-related and sensory-and-motor neurons tested in the cVMTrandomized were activated already during the first grasping motor act, but the selectivity for one of the two graspable targets emerged only during the execution of the second grasping. In contrast, when the cVMT was run in block, almost all these neurons not only discharged during the first grasping motor act, but also displayed the same target selectivity showed in correspondence of the hand contact with the target. Observation Task (OT). A great part of the neurons active during the OT showed a firing rate modulation in correspondence with the action performed by the experimenter. Among them, we found neurons significantly activated during the observation of the experimenter’s action (action observation-related neurons) and neurons responding not only to the action observation, but also to the presented cue stimuli (sensory-and-action observation-related neurons. Among the neurons of the first set, almost the half displayed a target selectivity, with a not clear difference between the two presented targets; Concerning to the second neuronal set, sensory-and-action related neurons, we found a low target selectivity and a not strictly congruence between the selectivity exhibited in the visual response and in the action observation.

Towards Closed-loop Deep Brain Stimulation: Behavior Recognition from Human STN

Deep brain stimulation (DBS) provides significant therapeutic benefit for movement disorders such as Parkinson’s disease (PD). Current DBS devices lack real-time feedback (thus are open loop) and stimulation parameters are adjusted during scheduled visits with a clinician. A closed-loop DBS system may reduce power consumption and side effects by adjusting stimulation parameters based on patient’s behavior. Thus behavior detection is a major step in designing such systems. Various physiological signals can be used to recognize the behaviors. Subthalamic Nucleus (STN) Local field Potential (LFP) is a great candidate signal for the neural feedback, because it can be recorded from the stimulation lead and does not require additional sensors. This thesis proposes novel detection and classification techniques for behavior recognition based on deep brain LFP. Behavior detection from such signals is the vital step in developing the next generation of closed-loop DBS devices. LFP recordings from 13 subjects are utilized in this study to design and evaluate our method. Recordings were performed during the surgery and the subjects were asked to perform various behavioral tasks. Various techniques are used understand how the behaviors modulate the STN. One method studies the time-frequency patterns in the STN LFP during the tasks. Another method measures the temporal inter-hemispheric connectivity of the STN as well as the connectivity between STN and Pre-frontal Cortex (PFC). Experimental results demonstrate that different behaviors create different m odulation patterns in STN and it’s connectivity. We use these patterns as features to classify behaviors. A method for single trial recognition of the patient’s current task is proposed. This method uses wavelet coefficients as features and support vector machine (SVM) as the classifier for recognition of a selection of behaviors: speech, motor, and random. The proposed method is 82.4% accurate for the binary classification and 73.2% for classifying three tasks. As the next step, a practical behavior detection method which asynchronously detects behaviors is proposed. This method does not use any priori knowledge of behavior onsets and is capable of asynchronously detect the finger movements of PD patients. Our study indicates that there is a motor-modulated inter-hemispheric connectivity between LFP signals recorded bilaterally from STN. We utilize a non-linear regression method to measure this inter-hemispheric connectivity and to detect the finger movements. Our experimental results using STN LFP recorded from eight patients with PD demonstrate this is a promising approach for behavior detection and developing novel closed-loop DBS systems.

Human brain regions required for the dividing and switching of attention between two features of a single object

This combined PET and ERP study was designed to identify the brain regions activated in switching and divided attention between different features of a single object using matched sensory stimuli and motor response. The ERP data have previously been reported in this journal [64]. We now present the corresponding PET data. We identified partially overlapping neural networks with paradigms requiring the switching or dividing of attention between the elements of complex visual stimuli. Regions of activation were found in the prefrontal and temporal cortices and cerebellum. Each task resulted in different prefrontal cortical regions of activation lending support to the functional subspecialisation of the prefrontal and temporal cortices being based on the cognitive operations required rather than the stimuli themselves. (C) 2003 Elsevier Science B.V. All rights reserved.

The application of proteomics to the human alcoholic brain

Alcoholism results in changes in the human brain that reinforce the cycle of craving and dependency, and these changes are manifest in the pattern of expression of proteins in key cells and brain areas. Described here is a proteomics-based approach aimed at determining the identity of proteins in the superior frontal cortex (SFC) of the human brain that show different levels of expression in autopsy samples taken from healthy and long-term alcohol abuse subjects. Soluble protein fractions constituting pooled samples combined from SFC biopsies of four well-characterized chronic alcoholics (mean consumption > 80 g ethanol/day throughout adulthood) and four matched controls (< 20 g/day) were generated. Two-dimensional electrophoresis was performed in triplicate on alcoholic and control samples and the resultant protein profiles analyzed for differential expression. Overall, 182 proteins differed by the criterion of twofold or more between case and control samples. Of these, 139 showed significantly lower expression in alcoholics, 35 showed significantly higher expression, and 8 were new or had disappeared. To date, 63 proteins have been identified using MALDI-MS and MS-MS. The finding that the expression level of differentially expressed proteins is preponderantly lower in the alcoholic brain is supported by recent results from parallel studies using microarray mRNA transcript.

Gene expression in profiling in individual cases reveals consistent transcriptional changes in alcoholic human brain

Chronic alcohol exposure induces lasting behavioral changes, tolerance, and dependence. This results, at least partially, from neural adaptations at a cellular level. Previous genome-wide gene expression studies using pooled human brain samples showed that alcohol abuse causes widespread changes in the pattern of gene expression in the frontal and motor cortices of human brain. Because these studies used pooled samples, they could not determine variability between different individuals. In the present study, we profiled gene expression levels of 14 postmortem human brains (seven controls and seven alcoholic cases) using cDNA microarrays (46 448 clones per array). Both frontal cortex and motor cortex brain regions were studied. The list of genes differentially expressed confirms and extends previous studies of alcohol responsive genes. Genes identified as differentially expressed in two brain regions fell generally into similar functional groups, including metabolism, immune response, cell survival, cell communication, signal transduction and energy production. Importantly, hierarchical clustering of differentially expressed genes accurately distinguished between control and alcoholic cases, particularly in the frontal cortex.

GABAA receptor beta subunit mRNA expression in the human alcoholic brain

A competitive RT-PCR assay was used to quantify the expression of the GABA(A) receptor beta(1), beta(2) and beta(3) isoform mRNA transcripts in the superior frontal cortex and motor cortex of 21 control and 22 alcoholic cases. A single set of primers was designed that permitted amplification of all three transcripts and the internal standard simultaneously; differentiation of the individual transcripts was achieved by restriction enzyme digestion. Construction of a standard curve, using the internal standard and a concentration range of beta(2) cRNA-enabled quantitation of mRNA expression levels. No significant difference in mRNA expression was found between the control and alcoholic case groups in either the superior frontal or motor cortex for the beta(2) or beta(3) isoforms. A significant interaction was found between isoform and area, although, the two case groups did not partition on this measure. The interaction was due to a significant difference between superior frontal and motor cortex for the beta(3) isoform; this regional comparison was not significant for beta(2) mRNA. Age at death and post-mortem delay (PMD) had no significant effect on beta mRNA expression in either case group in either region. A beta(1) signal could not be detected in the RT-PCR assay. (C) 2004 Elsevier Ltd. All rights reserved.

Effects of chronic exposure to low-level cadmium on renal tubular function and CYP2A6-mediated coumarin metabolism in healthy human subjects

Relationships between cadmium (Cd) body burden, kidney function and coumarin metabolism were investigated using two groups of 197 and 200 healthy Thais with men and women in nearly equal numbers. A mean age of one group was 30.5 years and it was 39.3 years for the other group. Of 397, 20 subjects (5%) excreted urine Cd between 1.4 mug/g and 3.8 mug/g creatinine and these subjects faced 10-15% increase in the probability of having abnormal urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG-uria). The prevalence of NAG-uria varied with Cd body burden in a dose-dependent manner (chi(2) = 22, P < 0.008). Also NAG-nuria was one of the three kidney effect markers tested that showed the greatest strength of correlation with urine Cd in both men and women (r = 0.48 P < 0.001). In addition, urine Cd excretion of men and women showed a positive correlation (r = 0.46 to 0.54. P < 0.001) with urine 7-hydroxycoumarin (7-OHC) excretion which was used as a marker of liver cytochrome P450 2A6 (CYP2A6) enzyme activity. Urinary CA excretion accounted for 25% of the total variation in urine 7-OHC excretion (P < 0.001). These data suggest that Cd may increase the expression of CYP2A6 in liver, resulting in enhanced coumarin metabolism in subjects with high Cd body burden. (C) 2003 Elsevier Ireland Ltd. All rights reserved.

Pontosubicular apoptosis ("necrosis") in human neonates with intrauterine growth retardation and placental infarction

In a previous study of 37 autopsied stillbirths with non-dysmorphic intrauterine growth retardation ( IUGR), 26 cases were associated with placental infarction, a morphologic marker of uteroplacental insufficiency. Nine of the 26 cases with both IUGR and placental infarction, where archival tissue was available, had grey matter ischaemic lesions that were subsequently identified as pontosubicular necrosis. This lesion is now regarded as a localized form of apoptosis. A further eight third trimester stillbirth cases with both IUGR and placental infarction were ascertained prospectively. Sixteen of these 17 cases showed pontosubicular apoptosis, identified morphologically and verified using activated caspase-3 and TUNEL. Five of the 17 cases showed apoptosis in the frontal or temporal cortex as well. In this current study, pontosubicular apoptosis was strongly associated with IUGR and placental infarction in third trimester stillborns, suggesting that uteroplacental insufficiency leading to chronic fetal hypoxaemia may cause cerebral apoptosis.

Pyramidal neurons of granular prefrontal cortex of the galago: Complexity in evolution of the psychic cell in primates

Typically, cognitive abilities of humans have been attributed to their greatly expanded cortical mantle, granular prefrontal cortex (gPFC) in particular. Recently we have demonstrated systematic differences in microstructure of gPFC in different species. Specifically, pyramidal cells in adult human gPFC are considerably more spinous than those in the gPFC of the macaque monkey, which are more spinous than those in the gPFC of marmoset and owl monkeys. As most cortical dendritic spines receive at least one excitatory input, pyramidal cells in these different species putatively receive different numbers of inputs. These differences in the gPFC pyramidal cell phenotype may be of fundamental importance in determining the functional characteristics of prefrontal circuitry and hence the cognitive styles of the different species. However, it remains unknown as to why the gPFC pyramidal cell phenotype differs between species. Differences could be attributed to, among other things, brain size, relative size of gPFC, or the lineage to which the species belong. Here we investigated pyramidal cells in the dorsolateral gPFC of the prosimian galago to extend the basis for comparison. We found these cells to be less spinous than those in human, macaque, and marmoset. (c) 2005 Wiley-Liss, Inc.