Storage Of Spatial Information Research Articles

Central FGF21 production regulates memory but not peripheral metabolism.

SUMMARYFibroblast growth factor 21 (FGF21) is a liver-derived endocrine hormone that functions to regulate energy homeostasis and macronutrient intake. Recently, FGF21 was reported to be produced and secreted from hypothalamic tanycytes, to regulate peripheral lipid metabolism; however, rigorous investigation of FGF21 expression in the brain has yet to be accomplished. Using a mouse model that drives CRE recombinase in FGF21-expressing cells, we demonstrate that FGF21 is not expressed in the hypothalamus, but instead is produced from the retrosplenial cortex (RSC), an essential brain region for spatial learning and memory. Furthermore, we find that central FGF21 produced in the RSC enhances spatial memory but does not regulate energy homeostasis or sugar intake. Finally, our data demonstrate that administration of FGF21 prolongs the duration of long-term potentiation in the hippocampus and enhances activation of hippocampal neurons. Thus, endogenous and pharmacological FGF21 appear to function in the hippocampus to enhance spatial memory.

Validation of Indonesian Words Memory Test

Working memory not only temporarily stores information but also actively processes information to perform complex cognitive tasks. Working memory components have different functions such as storing specific verbal and auditive information, visual and spatial information storage areas and there are components that control both systems. One way to retrieve stored information is by recall technique. This study used twelve concrete nouns tested in the form of 12 sequence formats. The twelve formats were tested on 120 people so that each format was tested on 10 participants. Each word produces scores based on achievement tests in each sequence. The participants of this study were adult individuals aged 19-30 years, consisting of 24 male and 96 female participants. Difficulty level (p) of each word, i.e the number of correct answers is divided by the number of total answerers, calculated in each order format. For each sequence a word is chosen with the difficulty level of p = 0.03-0.05. The participants of this study were adult individuals aged 19-30 years, consisting of 24 male and 96 female participants. This study developed a memory test of Indonesian nouns that had psychometric parameters.

The relationship between visuospatial neglect, spatial working memory and search behavior

ABSTRACTVisuospatial neglect (VSN) is characterized by a lateralized attentional deficit in the visual domain. In addition, patients with VSN might have an impairment in the temporary storage of spatial information in working memory (spatial working memory; SWM) that, like VSN, could impair systematic searching behavior. Several studies have demonstrated either SWM impairments or impaired searching behavior in VSN patients. Here, we related SWM performance to search behavior in patients with and without VSN. We assessed SWM using a novel task in a group of 182 stroke patients (24 with VSN, 158 without) and 65 healthy controls. We related SWM performance to available stroke-related and cognitive data. Patients with VSN exhibited lower SWM performance than patients without VSN and healthy controls. Additional control analyses indicated that differences in SWM performance are specific to visuospatial processing, instead of e.g. verbal working memory or the general level of physical disability. Last, we related SWM performance to visual search performance on cancellation tasks, one where their cancellation markings remained visible and another one where their prior cancellations markings were invisible to the patient and therefore patients had to remember which targets they had canceled. SWM performance correlated with search organization. Together, these results from a large sample of stroke patients corroborate the findings of earlier studies, while excluding several alternative explanations: SWM impairment is a part of the neglect syndrome, and SWM impairments are related to search behavior.

Spatial Navigation in Rats and Humans: A Neuropsychological Perspective

AbstractBackground and objective:In a landmark publication, O’Keefe & Dostrovsky (1971) presented a model for spatial navigation in the rat, the cognitive map theory. In this theory they proposed that the processing and storage of spatial information for spatial navigation takes place in the hippocampus. The theory was extended to include the contribution of the grid cells in the medial entorhinal cortex (Hafting et al. 2005). The cognitive map theory has been widely applied to spatial navigation in humans as well as rats. In this paper, an alternative theory is proposed in which spatial processing takes place in the right parieto-temporo-occipital area in humans, and that damage to this area causes a fragmentation in the sense of space, affecting the recall of both visual and tactile spatial information.Method:A group of eight subjects with damage to the right parieto-temporo-occipital area and a fragmented sense of space was assessed on tests of spatial navigation and memory and the results were compared with a group of patients with damage to the right hippocampus. Other comparison groups included left and right hemisphere subjects with normal spatial functioning.Results:The results suggest that, in the human, damage to the right parieto-temporo-occipital area causes a fragmentation in the sense of space, as well as an impaired memory for spatial material in both the visual and tactile modalities. These results support a model of spatial navigation in which the integrity of the right parieto-temporo-occipital area, and not the right hippocampus, is a necessary condition for the processing of spatial information in humans. An alternative explanation for the functioning of the right hippocampus is also presented.

Primate brain size is predicted by diet but not sociality.

The social brain hypothesis posits that social complexity is the primary driver of primate cognitive complexity, and that social pressures ultimately led to the evolution of the large human brain. Although this idea has been supported by studies indicating positive relationships between relative brain and/or neocortex size and group size, reported effects of different social and mating systems are highly conflicting. Here, we use a much larger sample of primates, more recent phylogenies, and updated statistical techniques, to show that brain size is predicted by diet, rather than multiple measures of sociality, after controlling for body size and phylogeny. Specifically, frugivores exhibit larger brains than folivores. Our results call into question the current emphasis on social rather than ecological explanations for the evolution of large brains in primates and evoke a range of ecological and developmental hypotheses centred on frugivory, including spatial information storage, extractive foraging and overcoming metabolic constraints.

Requiring collaboration: Hippocampal-prefrontal networks needed in spatial working memory and ageing. A multivariate analysis approach

Ageing is characterized by a decline in the processes of retention and storage of spatial information. We have examined the behavioural performance of adult rats (3months old) and aged rats (18months old) in a spatial complex task (delayed match to sample). The spatial task was performed in the Morris water maze and consisted of three sessions per day over a period of three consecutive days. Each session consisted of two trials (one sample and retention) and inter-session intervals of 5min. Behavioural results showed that the spatial task was difficult for middle aged group. This worse execution could be associated with impairments of processing speed and spatial information retention.We examined the changes in the neuronal metabolic activity of different brain regions through cytochrome C oxidase histochemistry. Then, we performed MANOVA and Discriminant Function Analyses to determine the functional profile of the brain networks that are involved in the spatial learning of the adult and middle-aged groups. This multivariate analysis showed two principal functional networks that necessarily participate in this spatial learning. The first network was composed of the supramammillary nucleus, medial mammillary nucleus, CA3, and CA1. The second one included the anterior cingulate, prelimbic, and infralimbic areas of the prefrontal cortex, dentate gyrus, and amygdala complex (basolateral l and central subregions). There was a reduction in the hippocampal-supramammilar network in both learning groups, whilst there was an overactivation in the executive network, especially in the aged group. This response could be due to a higher requirement of the executive control in a complex spatial memory task in older animals.

The effect of AMPA receptor blockade on spatial information acquisition, consolidation and expression in juvenile rats

Improvement on spatial tasks in rats is observed during a late, postnatal developmental period (post-natal day (PND) 18 – PND 20). The developmental emergence of this spatial function occurs in conjunction with hippocampal connectivity changes and enhanced hippocampal-AMPA receptor-mediated synaptic responses. The current work investigated the effect of AMPAr blockade on the emergence and long-term storage of spatial information in juvenile rats and associated neural activity patterns in the dorsal hippocampus CA1 region. Male, Long Evans rats between the ages of PND 18 and PND 20 were systemically (i.p.) administered the AMPAr antagonist, NBQX, (0, 5 or 10mg/kg) every day prior to hidden platform water maze training (PND 18, 19 and 20), every day immediately post-training or immediately before the probe test (PND 41). NBQX administration prior to training prolonged latencies, pathlength and increased thigmotaxis during the acquisition phase. Administration of NBQX immediately posttraining had no effect on the day-to-day performance. When given a probe test 3weeks later, the saline group across all conditions spent more time in the target quadrant. Rats treated with pretraining 5mg NBQX dose showed a preference for the target quadrant while the posttraining and pretesting 5mg NBQX doses impaired the target quadrant preference. Groups injected with 10mg of NBQX pretraining, posttraining or pretesting did not show a preference for the target quadrant. c-Fos labeling in the CA1 reflected these differences in probe performance in that groups showing greater than chance dwell time in the target quadrant showed more c-Fos labeling in the CA1 region than groups that did not show a target quadrant preference. These findings provide support for the critical role of AMPA receptor-mediated function in the organization and long-term storage of spatial memories acquired during the juvenile period.

Selective deficit of spatial short-term memory: Role of storage and rehearsal mechanisms

We report the neuropsychological and MRI investigation of a patient (GP) who developed a selective impairment of spatial short-term memory (STM) following damage to the dorso-mesial areas of the right frontal lobe. We assessed in this patient spatial STM with an experimental procedure that evaluated immediate and 5–20 s delayed recall of verbal, visual and spatial stimuli. The patient scored significantly worse than normal controls on tests that required delayed recall of spatial data. This could not be ascribed to a deficit of spatial episodic long-term memory because amnesic patients performed normally on these tests. Conversely, the patient scored in the normal range on tests of immediate recall of verbal, visual and spatial data and tests of delayed recall of verbal and visual data. Comparison with a previously described patient who had a selective deficit in immediate spatial recall and an ischemic lesion that affected frontal and parietal dorso-mesial areas in the right hemisphere (Carlesimo GA, Perri R, Turriziani P, Tomaiuolo F, Caltagirone C. Remembering what but not where: independence of spatial and visual working memory in the human brain. Cortex. 2001 Sep; 37(4):519–34) suggests that the right parietal areas are involved in the short-term storage of spatial information and that the dorso-mesial regions of the right frontal underlie mechanisms for the delayed maintenance of the same data.

Mechanisms of hippocampal astrocytes mediation of spatial memory and theta rhythm by gliotransmitters and growth factors.

Our knowledge about encoding and maintenance of spatial memory emphasizes the integrated functional role of the grid cells and the place cells of the hippocampus in the generation of theta rhythm in spatial memory formation. However, the role of astrocytes in these processes is often underestimated in their contribution to the required structural and functional characteristics of hippocampal neural network operative in spatial memory. We show that hippocampal astrocytes, by the secretion of gliotransmitters, such as glutamate, d-serine, and ATP and growth factors such as BDNF and by the expression of receptors and channels such as those of TNFα and aquaporin, have several diverse fuctions in spatial memory. We specifically focus on the role of astrocytes on five phases of spatial memory: (1) theta rhythm generation, (2) theta phase precession, (3) formation of spatial memory by mapping data of entorhinal grid cells into the place cells, (4) storage of spatial information, and (5) maintenance of spatial memory. Finally, by reviewing the literature, we propose specific mechanisms mentioned in the form of a hypothesis suggesting that astrocytes are important in spatial memory formation.

Encoding and storage of spatial information in the retrosplenial cortex.

The retrosplenial cortex (RSC) is part of a network of interconnected cortical, hippocampal, and thalamic structures harboring spatially modulated neurons. The RSC contains head direction cells and connects to the parahippocampal region and anterior thalamus. Manipulations of the RSC can affect spatial and contextual tasks. A considerable amount of evidence implicates the role of the RSC in spatial navigation, but it is unclear whether this structure actually encodes or stores spatial information. We used a transgenic mouse in which the expression of green fluorescent protein was under the control of the immediate early gene c-fos promoter as well as time-lapse two-photon in vivo imaging to monitor neuronal activation triggered by spatial learning in the Morris water maze. We uncovered a repetitive pattern of cell activation in the RSC consistent with the hypothesis that during spatial learning an experience-dependent memory trace is formed in this structure. In support of this hypothesis, we also report three other observations. First, temporary RSC inactivation disrupts performance in a spatial learning task. Second, we show that overexpressing the transcription factor CREB in the RSC with a viral vector, a manipulation known to enhance memory consolidation in other circuits, results in spatial memory enhancements. Third, silencing the viral CREB-expressing neurons with the allatostatin system occludes the spatial memory enhancement. Taken together, these results indicate that the retrosplenial cortex engages in the formation and storage of memory traces for spatial information.

The Neural Encoding of Space in Parahippocampal Cortices

The Neural Encoding of Space in Parahippocampal Cortices

Wnt transmembrane signaling and long‐term spatial memory

Transmembrane signaling mechanisms are critical for regulating the plasticity of neuronal connections underlying the establishment of long-lasting memory (e.g., Linden and Routtenberg (1989) Brain Res Rev 14:279-296; Sossin (1996) Trends Neurosci 19:215-218; Mayr and Montminy (2001) Nat Rev Mol Cell Biol 2:599-609; Chen et al. (2011) Nature 469:491-497). One signaling mechanism that has received surprisingly little attention in this regard is the well-known Wnt transmembrane signaling pathway even though this pathway in the adult plays a significant role, for example, in postsynaptic dendritic spine morphogenesis and presynaptic terminal neurotransmitter release (Inestrosa and Arenas (2010) Nat Rev Neurosci 11:77-86). The present report now provides the first evidence of Wnt signaling in spatial information storage processes. Importantly, this Wnt participation is specific and selective. Thus, spatial, but not cued, learning in a water maze selectively elevates the levels in hippocampus of Wnt 7 and Wnt 5a, but not the Wnt 3 isoform, indicating behavioral selectivity and isoform specificity. Wnt 7 elevation is subfield-specific: granule cells show an increase with no detectable change in CA3 neurons. Wnt 7 elevation is temporally specific: increased Wnt signaling is not observed during training, but is seen 7 days and, unexpectedly, 30 days later. If the Wnt elevation after learning is activity-dependent, then it may be possible to model this effect in primary hippocampal neurons in culture. Here, we evaluate the consequence of potassium or glutamate depolarization on Wnt signaling. This represents, to our knowledge, the first demonstration of an activation-dependent elevation of Wnt levels and surprisingly an increased number of Wnt-stained puncta in neurites suggestive of trafficking from the cell body to neuronal processes, probably dendrites. It is proposed that Wnt signaling pathways regulate long-term information storage in a behavioral-, cellular-, and isoform-specific manner.

The neural correlates of impaired collision avoidance in hemianopic patients

The aim of this study was to assess the brain regions associated with impaired performance in a virtual, dynamic collision avoidance task, in a group of patients with homonymous visual field defects (HVFDs) because of unilateral vascular brain lesions. Overall task performance was quantitatively assessed as the number of collisions while crossing an intersection at two levels of traffic density. Twenty-six patients were divided into two subgroups using the median split method: patients with 'performance above average' (HVFD(A), i.e. lower number of collisions) and patients with 'performance below average' (HVFD(B), i.e. higher number of collisions). In order to identify the anatomical structures that might be specifically affected in HVFD(B) patients but spared in HVFD(A) patients, overlap, subtraction and voxel-based lesion-symptom mapping analyses were performed using the MRIcron software. No significant difference in collision avoidance between patients with left- and right-hemispheric lesions was revealed. Separate lesion analysis in 12 patients with right- and 14 patients with left-hemispheric lesions showed that the cortical structures associated with impaired collision avoidance were the parieto-occipital region and posterior cingulate gyrus in the right hemisphere and the inferior occipital cortex and parts of the fusiform (occipito-temporal) gyrus in the left hemisphere. In the present collision avoidance paradigm, impaired performance of patients with right-hemispheric lesions is associated with damage in the dorsal processing stream and potential impact on the visual spatial working memory (WM), while impaired performance of patients with left-hemispheric lesions is associated with damage in the ventral stream and potential impact on the visual object WM.

A neurophysiological analysis of working memory in amyotrophic lateral sclerosis

Frontal lobe functions, in particular working memory (WM) and verbal fluency, have been found to be deficient in amyotrophic lateral sclerosis (ALS). To study the neural correlates of WM-impairment, ALS patients and healthy age-matched controls were subjected to two working memory tasks following the 2-back paradigm, one requiring the storage of figural information, the other storage of spatial information. A significant proportion of ALS patients were unable to perform the WM-tasks. Those who could showed worse performance in the spatial task than the controls. Event-related brain potentials recorded during the task revealed a topographical change of the working memory effect in the ALS patients. Thus, behavioral and electrophysiological data suggest an alteration of working memory, in particular for spatial information, in ALS. Additionally, the patients also took part in two Go/Nogo tasks (spatial, figural) using the same stimulus material but defining targets prior to the experiment instead of a working memory manipulation. Here, an anteriorization of the nogo-P3 was found which has been established as an index of impaired inhibitory functions.

Lidocaine injections targeting CA3 hippocampus impair long‐term spatial memory and prevent learning‐induced mossy fiber remodeling

Learning a spatial location induces remodeling of the mossy fiber terminal field (MFTF) in the CA3 subfield of the dorsal hippocampus (Ramirez-Amaya et al. (2001) J Neurosci 21:7340-7348; Holahan et al. (2006) Hippocampus 16:560-570; Rekart et al. (2007a) Learn Mem 14:416-421). These fibers appear to grow from the stratum lucidum into distal stratum oriens. Is this axonal growth dependent on “repeated and persistent” neural activity in the CA3 region during training? To address this issue, we targeted local inactivation of the MFTF region in a post-training, consolidation paradigm. Male Wistar rats, bilaterally implanted with chronic indwelling cannulae aimed at the MFTF CA3 region, were trained on a hidden platform water maze task (10 trials per day for 5 days). Immediately after the 10th trial on each training day, rats were injected with lidocaine (4% w/v; 171 mM; n=7) or phosphate-buffered saline (PBS; n=7). Behavioral measures of latency, path length, and thigmotaxis were recorded, as was directional heading. A retention test (probe trial) was given 7 days after the last training day, and brains were subsequently processed for MFTF distribution (Timm's stain) and cannula location. Lidocaine treatment was found to block the learning-associated structural remodeling of the MFTF that was reported previously and observed in the PBS-injected controls. During training, the lidocaine group showed elevated latencies and a misdirected heading to locate the platform on the first trial of each training day. On the 7-day retention probe trial, the lidocaine-injected group showed poor retention indicated by the absence of a search bias in the area where the platform had been located during training. These data suggest that the reduction of neuronal activity in the CA3 region impairs long-term storage of spatial information. As this was associated with reduced MFTF structural remodeling, it provides initial anatomical and behavioral evidence for an activity-dependent, presynaptic growth model of memory.

Myosin IIb Regulates Actin Dynamics during Synaptic Plasticity and Memory Formation

Reorganization of the actin cytoskeleton is essential for synaptic plasticity and memory formation. Presently, the mechanisms that trigger actin dynamics during these brain processes are poorly understood. In this study, we show that myosin II motor activity is downstream of LTP induction and is necessary for the emergence of specialized actin structures that stabilize an early phase of LTP. We also demonstrate that myosin II activity contributes importantly to an actin-dependent process that underlies memory consolidation. Pharmacological treatments that promote actin polymerization reversed the effects of a myosin II inhibitor on LTP and memory. We conclude that myosin II motors regulate plasticity by imparting mechanical forces onto the spine actin cytoskeleton in response to synaptic stimulation. These cytoskeletal forces trigger the emergence of actin structures that stabilize synaptic plasticity. Our studies provide a mechanical framework for understanding cytoskeletal dynamics associated with synaptic plasticity and memory formation.

The when and where of spatial storage in memory-guided saccades

The memory-guided saccade paradigm is an ideal experimental model for studying spatial working memory. Both the posterior parietal cortex and frontal cortex are known to play a role in working memory; however, there is much debate about the degree of their involvement in the retention of information. We used event-related potentials and electromagnetic tomography to clarify the precise time course and location of the neural correlates of spatial working memory during a memory-guided saccade task in humans. We observed sustained activity in the inferior parietal lobe and extrastriate areas that persisted for the entire duration of the sensory- and memory-phases. This time course reveals that these regions participate in both initial sensory processing of visual cues and in the short-term maintenance of spatial location memory. Similar sustained activation was also observed in the anterior cingulate cortex, probably reflecting attentive control during the task. Differential activity between conditions was also recorded in the dorsolateral prefrontal cortex and in the frontal eye fields, but only during the initial part of the memory-phase. This finding suggests that these areas are not involved in the storage of spatial information, but rather in response selection and in transformation of spatial information into a motor coordinate framework, respectively.By exploiting techniques that provide exquisite temporal resolution and reasonably precise anatomical localization, this study provides evidence supporting the key role of inferior parietal lobe in the storage of spatial information during a working memory guided saccade.

Odelo geodatabase en la estructuración y almacenamiento de información espacial para la administración y control del litoral Caribe colombiano

In this research the results of using the data model called Geo-database in the structuring and storage of spatial information of the Cartagena de Indias littorals, the Tierra Bomba island, the Morrosquillo Gulf and between Tajamar Occidental of Magdalena river and Puerto Velero during the years 2007 and 2008 in the Colombian Caribbean are presented. The research included identification of the Maritime National Direction corporative Geodatabase requirements, verification of state and structuring of the spatial information obtained by the Oceanographic and Hydrographic Research Center and establishing the procedure for structuring and later storage of the information. The use of the geodatabase model in the study areas, permitted the structuring, storing and quantification of spatial information of 303.44 kilometers of coastline, 1512.31 hectares corresponding to beach areas and 10469.5 hectares of low tidal zones. This information will be used by the National Maritime Authority and its respective Port authorities as technical support for the control, administration and preservation of these govern property located on the Colombian Caribbean littoral.

COMPUTATIONAL AND NONCOMPUTATIONAL SYSTEMS IN BRAIN AND COGNITION: CAN ONE MASK THE OTHER?

A theory is developed based on the premise that nonneural processes occur in the brain exemplified as spatial working memory, and is the seat of consciousness. Additionally, wave storage of spatial information, a Bose condensate to support the waves, and the location of wave storage are provided as illustrative, “existence proofs” that a coherent theory can be built along these lines in agreement with the data. The theory can be built argues on functional grounds that a nonneural spatial memory may serve a vital biological function. This article demonstrate how this same non-neural memory can bridge the explanatory gap to consciousness, in agreement with the facts. The article proposes a possible mechanism and location for the nonneural component.

Storage of Spatial Information by the Maintenance Mechanism of LTP

Analogous to learning and memory storage, long-term potentiation (LTP) is divided into induction and maintenance phases. Testing the hypothesis that the mechanism of LTP maintenance stores information requires reversing this mechanism in vivo and finding out whether long-term stored information is lost. This was not previously possible. Recently however, persistent phosphorylation by the atypical protein kinase C isoform, protein kinase Mzeta (PKMz), has been found to maintain late LTP in hippocampal slices. Here we show that a cell-permeable PKMz inhibitor, injected in the rat hippocampus, both reverses LTP maintenance in vivo and produces persistent loss of 1-day-old spatial information. Thus, the mechanism maintaining LTP sustains spatial memory.