Neural Representation of Abstract Task Structure During Generalization

Cognitive models in psychology and neuroscience widely assume that the human brain maintains an abstract representation of tasks. This assumption is fundamental to theories explaining how we learn quickly, think creatively, and act flexibly. However, neural evidence for a verifiably generative abstract task representation has been lacking. Here, we report an experimental paradigm that requires forming such a representation to act adaptively in novel conditions without feedback. Using functional magnetic resonance imaging, we observed that abstract task structure was represented within left mid-lateral prefrontal cortex, bilateral precuneus, and inferior parietal cortex. These results provide support for the neural instantiation of the long-supposed abstract task representation in a setting where we can verify its influence. Such a representation can afford massive expansions of behavioral flexibility without additional experience, a vital characteristic of human cognition

Increased Photosynthesis Contributes towards Improved Ovule-to-Seed Ratio in IAA Treated Range Grasses

Poor ovule-to-seed ratio is one of the major constraints in quality seed production in range grasses. Plant hormones per se or in the influence of external cues were known regulate the seed setting and their subsequent maturation in many crops. External application of hormones on the standing crops has shown very promising results but the physiological and biochemical phenomenon underlying such changes are not studied in detail. Exogenous application of different chemicals particularly during anthesis and post anthesis phases has increased the seed set in a number of species. Improved seed germination in Panicum maximum after foliar spray of indole acetic acid (IAA) has been reported by Malaviya et al., (2013). but the reason for improved seed germination was not very much clear. Auxin application has also been shown to induce fruit-set in many crops. Auxins with its prominent role in cell division have been implicated to play vital role in integument growth during early seed formation (Wu et al., 2006) and increased integuments has been correlated with increased seed size in Arabidopsis (Schruff et al., 2006) where they postulate that increased integument provides larger seed cavity which in turn provides a greater area of contact for endosperm with the seed coat, leading to increased nutrient uptake. Increase in photosynthesis rate due to foliar application of many phytohormones has also been reported in many crops and understanding source sink relationship as influenced by different growth regulators might lead to significant breakthrough in understanding the seed production as a whole and seed filling in particular. Though the role of plant growth regulators in seed production is well researched in many crops but not much work has been undertaken to improve the production and quality of seeds in range grasses. Panicum maximum and Cenchrus ciliaris are two most important range grasses of irrigated and non-irrigated conditions respectively and both produces seeds of very poor quality in terms of germination. Therefore, in present study we try to improve seed filling through foliar application of IAA in these crops and studied the photosynthesis behaviour post treatment

Lateral Prefrontal Cortex Subregions Make Dissociable Contributions during Fluid Reasoning

Reasoning is a key component of adaptable “executive” behavior and is known to depend on a network of frontal and parietal brain regions. However, the mechanisms by which this network supports reasoning and adaptable behavior remain poorly defined. Here, we examine the relationship between reasoning, executive control, and frontoparietal function in a series of nonverbal reasoning experiments. Our results demonstrate that, in accordance with previous studies, a network of frontal and parietal brain regions is recruited during reasoning. Our results also reveal that this network can be fractionated according to how different subregions respond when distinct reasoning demands are manipulated. While increased rule complexity modulates activity within a right lateralized network including the middle frontal gyrus and the superior parietal cortex, analogical reasoning demand—or the requirement to remap rules on to novel features—recruits the left inferior rostrolateral prefrontal cortex and the lateral occipital complex. In contrast, the posterior extent of the inferior frontal gyrus, associated with simpler executive demands, is not differentially sensitive to rule complexity or analogical demand. These findings accord well with the hypothesis that different reasoning demands are supported by different frontal and parietal subregions

Carbon Modeling of Agroforestry Systems at Farmers’ Field in Indo-Gangetic Plains of India

The Indian Green revolution region “Indo-Gangetic Plain” (IGP) comprises of four agro-climatic zones namely lower, middle, upper, and trans gangetic plains covering West Bengal, Bihar, Uttar Pradesh, Delhi, Uttarakhand, Chandigarh, Haryana, Punjab, and some part of Rajasthan state. It covers 169 districts with total geographical area of 43.70 million ha. The Indo-Gangetic plains are one of the most populous regions with its area covering nearly 13% of the total geographical area of the country. It produces about 50% of the total food grains to feed 40% of the population. The continuous cropping of rice-wheat system has degraded the soil health dramatically over the years. Hence, the incorporation of trees in agriculture would be a better option to improve the soil as well as livelihood of the farmers in IGP. Agriculture is the major enterprise of the region that is most vulnerable to climate changes particularly owing to the inadequacy of resources with the smallholder farmers. While, agroforestry has the potential to play a significant role in mitigating the atmospheric accumulation of greenhouse gases (GHG), it also helps smallholder farmers adapt to the changes. These are the reasons for recognizing agroforestry as a viable alternative to prevent and mitigate climate change (Ram Newaj et al., 2014). A considerable proportion of agroforestry area located in IGP and some of the promising tree species like Populus deltoides, Eucalyptus tereticornis, Melia azadirach, Mangifera indica, Dalbergia sissoo, and Acacia nilotica are very common in the farmer’s fields. Keeping this in view, the field survey was carried out to estimate the carbon sequestration potential at a farmer’s field in IGP

Similar or Different? The Role of the Ventrolateral Prefrontal Cortex in Similarity Detection

Patients with frontal lobe syndrome can exhibit two types of abnormal behaviour when asked to place a banana and an orange in a single category: some patients categorize them at a concrete level (e.g., “both have peel”), while others continue to look for differences between these objects (e.g., “one is yellow, the other is orange”). These observations raise the question of whether abstraction and similarity detection are distinct processes involved in abstract categorization, and that depend on separate areas of the prefrontal cortex (PFC). We designed an original experimental paradigm for a functional magnetic resonance imaging (fMRI) study involving healthy subjects, confirming the existence of two distinct processes relying on different prefrontal areas, and thus explaining the behavioural dissociation in frontal lesion patients. We showed that: 1) Similarity detection involves the anterior ventrolateral PFC bilaterally with a right-left asymmetry: the right anterior ventrolateral PFC is only engaged in detecting physical similarities; 2) Abstraction per se activates the left dorsolateral PFC

HEMANGIOME DU GRELE (A PROPOS D’UN CAS)

The small bowel hemangioma is a rare vascular tumour, can be revealed by a digestive hemorrhage. The authors report a 46 years old patient presenting a jejunal hemangioma discovered by a secondary severe anemia with repeated episodes of moelena. Endoscopic and radiological explorations were not evocative. The diagnosis was retained by the peroperative enteroscopy. The surgical operation consisted of an ileal exeresis with a termino-terminal anastomosis. The histologic study showed a diffuse intestinal hemangiomatosis. The postoperative continuations were marked by the bleeding repetition. The diffuse hemangiomas raise two difficulties: on the one hand, a problem of positive diagnosis, and on the other hand, a problem of therapeutic management, which obscures their prognosis.L’hémangiome du grêle est une tumeur vasculaire rare, peut être révélée par une hémorragie digestive. Les auteurs rapportent le cas d’un hémangiome du jéjunum chez un patient âgé de 46 ans, découvert par une anémie sévère secondaire à des épisodes répétés de moelena. Les explorations endoscopiques et radiologiques n’étaient pas évocatrices. Le diagnostic a été retenu par l’entéroscopie peropératoire. L’intervention chirurgicale a consisté en une résection iléale avec une anastomose termino-terminale. L’étude anatomopathologique a conclu à une hémangiomatose intestinale diffuse. Les suites postopératoires étaient marquées par la récidive du saignement. Les hémangiomes diffus posent deux difficultés : d’une part, un problème de diagnostic positif, et d’autre part, un problème de prise en charge thérapeutique, ce qui assombrit leur pronostic

The Function and Organization of Lateral Prefrontal Cortex: A Test of Competing Hypotheses

The present experiment tested three hypotheses regarding the function and organization of lateral prefrontal cortex (PFC). The first account (the information cascade hypothesis) suggests that the anterior-posterior organization of lateral PFC is based on the timing with which cue stimuli reduce uncertainty in the action selection process. The second account (the levels-of-abstraction hypothesis) suggests that the anterior-posterior organization of lateral PFC is based on the degree of abstraction of the task goals. The current study began by investigating these two hypotheses, and identified several areas of lateral PFC that were predicted to be active by both the information cascade and levels-of-abstraction accounts. However, the pattern of activation across experimental conditions was inconsistent with both theoretical accounts. Specifically, an anterior area of mid-dorsolateral PFC exhibited sensitivity to experimental conditions that, according to both accounts, should have selectively engaged only posterior areas of PFC. We therefore investigated a third possible account (the adaptive context maintenance hypothesis) that postulates that both posterior and anterior regions of PFC are reliably engaged in task conditions requiring active maintenance of contextual information, with the temporal dynamics of activity in these regions flexibly tracking the duration of maintenance demands. Activity patterns in lateral PFC were consistent with this third hypothesis: regions across lateral PFC exhibited transient activation when contextual information had to be updated and maintained in a trial-by-trial manner, but sustained activation when contextual information had to be maintained over a series of trials. These findings prompt a reconceptualization of current views regarding the anterior-posterior organization of lateral PFC, but do support other findings regarding the active maintenance role of lateral PFC in sequential working memory paradigms

Neural Mechanisms of Interference Control in Working Memory: Effects of Interference Expectancy and Fluid Intelligence

A critical aspect of executive control is the ability to limit the adverse effects of interference. Previous studies have shown activation of left ventrolateral prefrontal cortex after the onset of interference, suggesting that interference may be resolved in a reactive manner. However, we suggest that interference control may also operate in a proactive manner to prevent effects of interference. The current study investigated the temporal dynamics of interference control by varying two factors - interference expectancy and fluid intelligence (gF) - that could influence whether interference control operates proactively versus reactively.A modified version of the recent negatives task was utilized. Interference expectancy was manipulated across task blocks by changing the proportion of recent negative (interference) trials versus recent positive (facilitation) trials. Furthermore, we explored whether gF affected the tendency to utilize specific interference control mechanisms. When interference expectancy was low, activity in lateral prefrontal cortex replicated prior results showing a reactive control pattern (i.e., interference-sensitivity during probe period). In contrast, when interference expectancy was high, bilateral prefrontal cortex activation was more indicative of proactive control mechanisms (interference-related effects prior to the probe period). Additional results suggested that the proactive control pattern was more evident in high gF individuals, whereas the reactive control pattern was more evident in low gF individuals.The results suggest the presence of two neural mechanisms of interference control, with the differential expression of these mechanisms modulated by both experimental (e.g., expectancy effects) and individual difference (e.g., gF) factors

The mind's eye, looking inward? In search of executive control in internal attention shifting

In studies of mental counting, participants are faster to increment a count that was just incremented (no-switch trial) than to increment a different count (switch trial). Investigators have attributed the effect to a shift in the internal focus of attention on switch trials. Here we report evidence for other bottom-up and top-down contributions. Two stimuli were mapped to each of two counts. The no-switch facilitation was greater when stimuli repeated than when they were different. Event-related potential (ERP) activity associated with repetitions was anterior to that associated with switching. Runs of no-switch trials elicited faster responses and frontal ERP activity. Runs of switches and large counts both elicited slow responses and reduced P300 amplitudes. Bottom-up processes may include priming on no-switch trials and conflict on switch trials. Top-down processes may control conflict, subvocal rehearsal, and the contents of working memory.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73572/1/1469-8986.00059.pd