Optical memory and spatial chaos.
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Journal Article↗
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Results for “spatial memory”
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Prolonged cannabinoid treatment results in spatial working memory deficits and impaired long-term potentiation in the CA1 region of the hippocampus in vivo.
Adult male Long-Evans rats were administered the potent cannabinoid 1 receptor agonist HU-210 (100 microg/kg, i.p.) for 15 days continuously and their performance on a matching-to-place version of the Morris water maze was subsequently evaluated. Overall, experimental animals performed significantly worse initially on the reference memory component of this task, but their performance improved over 5 days until it was indistinguishable from that of control animals. Animals given HU-210 did not exhibit working memory impairments at short intertrial delays (30 s); however, significant impairments were observed in learning performance with longer intertrial delays (300 s). In vivo electrophysiological analyses revealed that long-term potentiation in the CA1 region of the hippocampus was significantly impaired following the administration of HU-210 for 15 days. These results indicate that long-term cannabinoid exposure can produce marked deficits in reference and working memory performance, and also impair hippocampal synaptic plasticity in vivo.
Animals↗
Discovering spatial working memory fields in prefrontal cortex.
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Animals↗
Neural systems for visual orienting and their relationships to spatial working memory.
We investigated neural correlates of human visual orienting using event-related functional magnetic resonance imaging (fMRI). When subjects voluntarily directed attention to a peripheral location, we recorded robust and sustained signals uniquely from the intraparietal sulcus (IPs) and superior frontal cortex (near the frontal eye field, FEF). In the ventral IPs and FEF only, the blood oxygen level dependent signal was modulated by the direction of attention. The IPs and FEF also maintained the most sustained level of activation during a 7-sec delay, when subjects maintained attention at the peripheral cued location (working memory). Therefore, the IPs and FEF form a dorsal network that controls the endogenous allocation and maintenance of visuospatial attention. A separate right hemisphere network was activated by the detection of targets at unattended locations. Activation was largely independent of the target's location (visual field). This network included among other regions the right temporo-parietal junction and the inferior frontal gyrus. We propose that this cortical network is important for reorienting to sensory events.
Adolescent↗
Magical ideation and right-sided hemispatial inattention on a spatial working memory task: influences of sex and handedness.
A correlation between magical ideation scores and the size of relative right-sided hemispatial inattention was previously reported for healthy right-handed men performing a tactile line-bisection task. To re-investigate this relation, a computerized version of Corsi's Block-Tapping Test was used to test working memory. In this version, different numbers of cubes are similtaneously displayed on a screen, and after the cubes disappear the subject is asked to designate the cubes' locations on a grid as quickly as possible. 98 healtly medical students were divided into four groups on the basis of their handedness and sex in the following way: right-handed men, right-handed women, nonright-handed men, and nonright-handed women. Each subject performed the test once with the right hand and once with the left hand. Accuracy and Neglect scores were computed for the two hemispaces separately. Also, all subjects filled in the Magical Ideation Scale which asks for hallucination-like experiences and delusion-like beliefs. In all groups a significant right-sided inattention was found when subjects performed with the right hand. Magical Ideation scores were significantly correlated with Neglect in the right hemispace for the right-handed women when the right hand was used. For the nonright-handed men, when the right hand was used, a significant negative correlation between Magical Ideation scores and Neglect scores in the left hemispace was found. Our findings support the previous study in some aspects and suggest that the correlation between hemispatial inattention and proneness to schizotypy in normal subjects is restricted to right-hand performance.
Adult↗
Auditory and visual spatial working memory.
A series of experiments compared short-term memory for object locations in the auditory and visual modalities. The stimulus materials consisted of sounds and pictures presented at different locations in space. Items were presented in pure- or mixed-modality lists of increasing length. At test, participants responded to renewed presentation of the objects by indicating their original position. If two independent modality-specific and resource-limited short-term memories support the remembering of locations, memory performance should be higher in the mixed-modality than in the pure-modality condition. Yet, memory performance was the same for items in both types of list. In addition, responses to the memory load manipulation in both modalities showed very similar declines in performance. The results are interpreted in terms of object files binding object and location information in episodic working memory, independently of the input modality.
Association Learning↗
Neural mechanisms of spatial working memory: contributions of the dorsolateral prefrontal cortex and the thalamic mediodorsal nucleus.
The dorsolateral prefrontal cortex (DLPFC) has been known to play an important role in working memory. Neurophysiological studies have revealed that delay period activity observed in the DLPFC is a neural correlate of the temporary storage mechanism for information and that this activity represents either retrospective or prospective information, although the majority represents retrospective information. However, the DLPFC is not the only brain area related to working memory. The analysis of neural activity in the thalamic mediodorsal (MD) nucleus reveals that the MD also participates in working memory. Although similar task-related activities were observed in the MD, the directional bias of these activities and the proportion of presaccadic activity are different between the MD and the DLPFC. These results indicate that, although the MD participates in working memory, the way it participates in this process is different between these two areas, in that the MD participates more in motor control aspects than the DLPFC does.
Animals↗
Bidirectional modulation of spatial working memory by ethanol.
BACKGROUND: It is common knowledge that ethanol causes cognitive and memory impairments. Although these deficits are attributed to its central depressant properties, ethanol has biphasic effects and at low doses can produce excitatory actions. METHODS: Here we examined whether ethanol could have biphasic effects on performance in a delayed alternation task in a T-maze, a behavioral test of working memory. RESULTS: A dose-response study showed that intermediate doses of ethanol (1 g/kg) were associated with impairments of working memory in rats, as assessed at short intertrial intervals (10 sec). In contrast, at longer delays (120 sec), when the delayed alternation performance was reduced markedly in controls, a lower dose of ethanol (0.5 g/kg) significantly improved working memory. CONCLUSIONS: These results demonstrate a dose-dependent, bidirectional effect of ethanol on working memory and implicate the prefrontal cortex, the site of working memory function, as a target of ethanol action. The cognitive improvements caused by low, excitatory doses of ethanol may be perceived as rewarding and could have relevance for chronic ethanol consumption in humans.
Animals↗
Neurons responding to whole-body motion in the primate hippocampus.
We describe here hippocampal cells that respond during whole-body motion when a monkey is moved on a remote-controlled robot-mounted platform in a cue-controlled test chamber (2 x 2 x 2 m). Some of these cells responded to linear motion, and others to axial rotation. Some of these cells responded when the same motion occurred without a view of the visual field. Such cells appeared to be driven by vestibular inputs. Other cells required a view of the visual field for their response, and these cells appeared to be driven by the visual motion relative to the monkey of the test chamber. Further evidence that this was the case was that some of the cells responded to rotation and linear motion of the test chamber while the monkey remained stationary. Other cells responded to combinations of whole-body motion and a view of the environment. These findings show that information about whole-body motion, as well as about where the animal is looking in an environment, is represented in the primate hippocampus. We suggest that this information is important in spatial memory and thus in spatial navigation.
Animals↗
Transplantation of cholinergic-rich spinal tissue from spontaneously aborted human fetuses into a rodent model of Alzheimer's disease.
The results from this study provided the first piece of evidence that intrahippocampal transplants of cholinergic-rich spinal grafts derived from a human fetus can ameliorate the performance of fornix lesioned rats in both spatial reference memory and spatial navigation tasks. Although many questions remain to be answered, these results point to the therapeutic potential of human fetus-derived cholinergic-rich grafts in treating spatial memory impairments.
Abortion, Spontaneous↗
Relationship between cognitive impairment and clinical status in chronic heart failure patients.
BACKGROUND: In spite of its clinical importance, cognitive functioning is not always taken into account in studies on patients with chronic heart failure. The aim of the present study is to analyse the relationship between cognitive impairment and cardiovascular variables in a sample of patients with chronic heart failure for assessment or candidated for heart transplant. METHODS: Sixty-four male patients with chronic heart failure in NYHA class I-III, in a stable clinical condition, underwent cardiological evaluation and neuropsychological assessment by means of a wide battery of tests: Spinnler and Tognoni's tests and WAIS scale. RESULTS: Compared to the normative group, only 9% of patients did not have impairment in any cognitive function. 26% of patients had impairment of one cognitive function, and 30% of four or more cognitive functions. The cognitive functions that were most often impaired were short-term verbal memory, short-term visual spatial memory, differed verbal memory and verbal learning and visual spatial logical ability. On the whole, no statistical significant relationship was found between cognitive scores and the considered cardiovascular variables. CONCLUSIONS: Our data support the need to take into account the risk of cognitive impairment in CHF patients, regardless of age, disease severity or functional status. The high prevalence of short-term verbal memory impairment has important implications in clinical practice, since CHF patients should be actively involved in the medical management of their disease. Memory deficits could compromise patient's adherence to treatment as well as doctor-patient interactions. The practical consequences of these difficulties require some changes in doctors' behaviour and suggest the need for specific medical staff member training.
Chronic Disease↗
Effects of daily environmental enrichment on memory deficits and brain injury following neonatal hypoxia-ischemia in the rat.
Environmental enrichment (EE) results in improved learning and spatial memory, as well as attenuates morphological changes resulting from cerebral ischemia in adult animals. This study examined the effects of daily EE on memory deficits in the water maze and cerebral damage, assessed in the hippocampus and cerebral cortex, caused by neonatal hypoxia-ischemia. Male Wistar rats in the 7th postnatal day were submitted to the Levine-Rice model of neonatal hypoxia-ischemia (HI), comprising permanent occlusion of the right common carotid artery and a period of hypoxia (90 min, 8%O(2)-92%N(2)). Starting two weeks after the HI event, animals were stimulated by the enriched environment (1h/day for 9 weeks); subsequent to the stimulation, performance of animals in the water maze was assessed. HI resulted in spatial reference and working memory impairments that were completely reversed by EE. Following the behavioral study, animals were killed and the hippocampal volume and cortical area were estimated. There was a significant reduction of both hippocampal volume and cortical area, ipsilateral to arterial occlusion, in HI animals; environmental stimulation had no effect on these morphological measurements. Presented data indicate that stimulation by the daily environmental enrichment recovers spatial memory deficits caused by neonatal hypoxia-ischemia without affecting tissue atrophy in either hippocampus or cortex.
Analysis of Variance↗
The effects of chronic administration of hydrocortisone on cognitive function in normal male volunteers.
RATIONALE: Corticosteroids are elevated in certain neuropsychiatric disorders and this may contribute to the neuropsychological impairments reported in these disorders. OBJECTIVE: To examine the effects of hydrocortisone on learning, memory and executive function. METHODS: Hydrocortisone 20 mg was administered twice daily for 10 days to normal male volunteers in a randomized, placebo control, crossover, within-subject design. Learning, memory and executive function were measured using selected subtests from the Cambridge Neuropsychological Test Automated Battery. RESULTS: Hydrocortisone caused impairments of visuo-spatial memory. These included increased within search errors and impaired use of strategies on the spatial working memory subtest. In addition, administration of hydrocortisone was associated with more errors in the paired associate learning subtest, although no effect was found on the Tower of London. Hydrocortisone speeded response latencies in certain tests (pattern and spatial recognition memory). CONCLUSION: These results indicate that chronic administration of hydrocortisone leads to deficits in certain tests of cognitive function sensitive to frontal lobe dysfunction and may contribute to the cognitive impairment reported in certain neuropsychiatric disorders.
Adult↗
Working memory in young children: evidence for modality-specificity and implications for cerebral reorganization in early childhood.
Digit span (DS) and visual-spatial memory span (VMS) tasks have been considered indices of auditory and visual spatial processing, respectively, often classified as "primary memory" or "attention". There has been limited evidence for their modality specificity, however. We present two children who showed visual spatial processing deficiencies (including VMS) and non-dominant manual inefficiency with normal visual-spatial perception, auditory-verbal processing and dominant fine manual skills. These children support a distinction between auditory and visual-spatial memory span. These findings are discussed with regard to a hypothesis that the unique expression of VMS is time-limited, that visual-spatial processing becomes more verbalized as children learn to read and that these behavioral changes produce a lateral shift in cortical processing of visual spatial information.
Attention↗
Chronic treatment of old rats with donepezil or galantamine: effects on memory, hippocampal plasticity and nicotinic receptors.
The function of the cholinergic system is known to change during normal aging and in pathological conditions such as Alzheimer's disease. The present study was designed to assess, within the same group of old animals, the behavioral, electrophysiological and neurochemical effects of chronic treatment with agents that increase the function of the cholinergic system through both muscarinic and nicotinic mechanisms. Doses were determined that produced 60% cholinesterase inhibition by donepezil and galantamine for the old rats. This was chosen to be analogous to therapeutic levels achieved for treatment of human Alzheimer's disease patients with these agents. Because of the well-known age-related changes in spatial memory and hippocampal synaptic plasticity, spatial working memory in the radial eight-arm maze and hippocampal long-term potentiation induction and decay, as well as nicotinic receptor density and affinity, were measured in old rats implanted with minipumps that delivered donepezil, galantamine or saline. There was no effect of drug treatment on baseline synaptic transmission or on the threshold or magnitude of long-term potentiation induction. Both drug treatment groups, however, showed significantly extended long-term potentiation decay times at the perforant path-granule cell synapse over the saline control animals, as measured during the week following induction. Both drugs also elevated the number of nicotinic receptors within the hippocampus and neocortex. This is the first demonstration of cholinergic modulation of synaptic plasticity over the time-course of days. Furthermore, the durability of long-term potentiation was significantly, positively correlated with nicotinic receptor binding in the hippocampus. Chronic treatment with donepezil or galantamine had no significant effect on a well-learned spatial working memory task on the radial maze. These data suggest that the therapeutic doses of cholinesterase inhibitors used to treat patients with Alzheimer's disease may have effects on neurophysiology and neurochemistry that are close to the threshold for producing detectable behavioral improvements.
Acetylcholinesterase↗
The spatial brain.
Themes emerging from the collection of articles in the Special Section on Long-Term Spatial Memory include the notion of multiple spatial systems, the relation between spatial representations and episodic memory, the role of context, and the neural systems involved in space. The authors conclude that distinguishing between egocentric and allocentric spatial systems makes sense of both behavioral and neurobiological data. The special role of the hippocampal system in allocentric space, and as a consequence, in context, suggests how a spatial system might end up central to the ability to remember episodes.
Brain↗
Selective cognitive deficits in obsessive-compulsive disorder compared to panic disorder with agoraphobia.
OBJECTIVE: Visual-spatial and executive functions deficits have been reported in obsessive-compulsive disorder (OCD). We investigated their specificity comparing cognitive function in OCD, panic disorder with agoraphobia (PD/A) and controls by a comprehensive neuropsychological battery. METHOD: Fifty-five subjects (25 OCD, 15 PD/A, 15 controls) without current depressive episode underwent structured clinical interview for DSM-IV, Yale-Brown Obsessive Compulsive Scale, Hamilton Anxiety Rating Scale, Hamilton Depression Rating Scale. Neuropsychological battery assessed: executive functions, visual discrimination, spatial memory and learning, verbal memory, general intellectual functioning. RESULTS: OCD showed controlled fluency, visual-spatial construction, learning and memory deficits; PD/A spatial learning impairment. OCD was discriminated from PD/A and controls by three tests scores, predicting group membership for 76.4% of the cases. CONCLUSION: Visual-constructive and controlled fluency deficits seem specific in OCD, while the spatial learning deficit, shared with PD patients, may not be disorder-specific, but anxiety-related. Results support the proposed ventral frontal-striatal circuit involvement in OCD.
Adolescent↗
Accelerated senescence prone mouse-8 shows early onset of deficits in spatial learning and memory in the radial six-arm water maze.
Available data indicate that the senescence-accelerated prone mouse 8 (SAMP8) is an appropriate model of brain aging, with impairments in nonspatial learning and memory beginning as early as 2 months of age, and spatial learning and memory deficiencies not becoming apparent until after 4 months of age. However, with other strains (e.g., C57BL mice), the impairment in spatial memory was found earlier than that in nonspatial memory. We considered the possibility that the observed differences could be due to strain-specific differences in the training equipment. In the present study, a new optimized testing apparatus-the radial six-arm water maze (RAWM)-for detecting spatial learning and memory in mice, was employed, to determine whether there is impairment of spatial learning and memory in young SAMP8. The relationship between the spatial learning measures observed with the RAWM and the Morris maze, a classic spatial learning and memory testing apparatus, was also explored. It was found that, in the RAWM, rather than in the Morris maze, the impairment in spatial learning could be measured in SAMP8 mice as early as 3 months old, and the impairment in spatial memory in SAMP8 mice aged 5 months. These results suggested that the spatial learning and memory deficiencies could be found in early life of SAMP8 mice, and that RAWM and Morris maze each detect different aspects of spatial learning and memory.
Aging↗