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Mood and spatial memory: emotion and right hemisphere contribution to spatial cognition.

Depressed persons show an impairment of spatial cognition that may reflect the influence of affective arousal on right hemisphere cognition. We examined normal university students to determine whether individual differences in mood and arousal levels would be related to performance on a spatial memory task. Right-hemisphere specialization for this spatial memory task was confirmed by a left field advantage for the targets and this field asymmetry was enhanced as task difficulty was increased. Event-related brain potentials (ERPs), assessed with a 64-channel sensor array, showed a processing negativity contralateral to the target in the P300 interval (300-500 ms after the target appeared). This effect increased as task difficulty was increased. A stronger posterior negativity for good (rather than bad) targets may suggest that attention was allocated toward the good locations. A suggestion of right hemisphere sensitivity to mood in this normal sample was a tendency for the subjects high in Negative Arousal not to show the normal right hemisphere (left field) superiority for the spatial memory task. Interestingly, a medial frontal lobe negativity was elicited in the ERPs by the bad targets, perhaps paralleling the error-related negativity observed in other paradigms. This medial frontal negativity was also seen in response to the feedback stimulus for the bad targets. Motivation may be important to this frontal effect: It was enhanced for subjects describing themselves as high in either positive or negative affective arousal during the task.

Adolescent↗

Interference in spatial memory.

Four experiments examined interference in human spatial memory. The first two tested for retroactive interference by varying the similarity between the interpolated task and the task that was learned originally. Retroactive interference was observed during relearning of a radial stylus maze and during relearning of the locations of pairs of playing cards in a concentration game. In the third and fourth experiments, proactive interference was tested during the relearning of the locations of pairs in a concentration game. Some proactive interference was observed when the number of proactive games was varied (Experiment 3), and substantial proactive interference was found when the similarity between the proactive and target tasks was the independent variable (Experiment 4). Although extensive evidence indicates that spatial memory differs from other types of memory, spatial memory is subject to interference effects, as are verbal memory, motor memory, visual discriminative memory in animals, and animal spatial memory.

Adult↗

Animal models of declining memory in the aged: short-term and spatial memory in the aged rat.

Short-term and spatial memory were studied in Fischer 344 rats ranging in age from 6 to 26 months of age. Spatial memory, as measured by performance in an 8-armed radial maze, declined gradually with age. In contrast, short-term memory, as measured by retention of previous choices in the spatial maze over short intervals and performance on a modified form of Konorski's discriminated delayed response task, did not decline differentially as a function of age. These findings may be comparable to those obtained in the aged human, who also show marked deficits in spatial memory and little change in primary memory under appropriate test conditions.

Aging↗

Sex differences and menstrual cycle effects in human spatial memory.

A typical test of spatial memory requires subjects to relocate a number of objects in their original, previously studied positions. It has been argued that this test includes multiple separate processing components (Postma, A., De Haan, E.H.F., 1996. Quarterly Journal of Experimental Psychology 48A (1), 178-199; Postma, A., Izendoorn, R., De Haan, E.H.F., 1998. Brain and Cognition 36, 334-345). One has to encode the precise positions occupied, assign the various objects to the correct (relative) locations, and achieve an integration of both types of spatial information. The present study examined the presence of sex differences and the role of hormonal factors for these selective components of spatial memory. A computerised, immediate (working) memory version of the test was used, comparing 23 males and 34 females on three experimental conditions: positions only, object-to-position-assignment, and the combined condition, requiring integration of the other two components. In line with previous research (Postma et al., 1998) males showed a selective advantage for fine-grained, metric positional reconstruction (i.e. positions-only). Interestingly, a within-subjects comparison in the females only revealed a menstrual cycle effect for exactly the same dimension of spatial memory. In the nonmenstrual phase, females were better than during menstruation. This clearly implies a role for sex hormones in spatial memory, even though a subsequent analysis of testosterone samples in saliva did not reveal a significant correlation with measures of spatial memory in both males and females.

Adolescent↗

Rat spatial memory tasks adapted for humans: characterization in subjects with intact brain and subjects with selective medial temporal lobe thermal lesions.

In the present paper we describe five tests, 3 of which were designed to be similar to tasks used with rodents. Results obtained from control subjects, patients with selective thermo-coagulation lesions to the medial temporal lobe and results from non-human primates and rodents are discussed. The tests involve memory for spatial locations acquired by moving around in a room, memory for objects subjects interacted with, or memory for objects and their locations. Two of the spatial memory tasks were designed specifically as analogs of the Morris water task and the 8-arm radial-maze tasks used with rats. The Morris water task was modeled by hiding a sensor under the carpet of a room (Invisible Sensor Task). Subjects had to learn its location by using an array of visual cues available in the room. A path integration task was developed in order to study the non-visual acquisition of a cognitive representation of the spatial location of objects. In the non-visual spatial memory task, we blindfolded subjects and led them to a room where they had to find 3 objects and remember their locations. We designed an object location task by placing 4 objects in a room that subjects observed for later recall of their locations. A recognition task, and a novelty detection task were given subsequent to the recall task. An 8-arm radial-maze was recreated by placing stands at equal distance from each other around the room, and asking subjects to visit each stand once, from a central point. A non-spatial working memory task was designed to be the non-spatial equivalent of the radial maze. Search paths recorded on the first trial of the Invisible Sensor Task, when subjects search for the target by trial and error are reported. An analysis of the search paths revealed that patients with lesions to the right or left hippocampus or parahippocampal cortex employed the same type of search strategies as normal controls did, showing similarities and differences to the search behavior recorded in rats. Interestingly, patients with lesions that included the right parahippocampal cortex were impaired relative to patients with lesions to the right hippocampus that spared the parahippocampal cortex, when recall of the sensor was tested after a 30 min delay (Bohbot et al. 1998). No differences were obtained between control subjects and patients with selective thermal lesions to the medial temporal lobe, when tested on the radial-maze, the non-spatial analogue to the radial-maze and the path integration tasks. Differences in methodological procedures, learning strategies and lesion location could account for some of the discrepant results between humans and non-human species. Patients with lesions to the right hippocampus, irrespective of whether the right parahippocampal cortex was spared or damaged, had difficulties remembering the particular configuration and identity of objects in the novelty detection of the object location task. This supports the role of the human right hippocampus for spatial memory, in this case, involving memory for the location of elements in the room; learning known to require the hippocampus in the rat.

Adolescent↗

Acute ethanol administration selectively impairs spatial memory in C57BL/6J mice.

It has been shown in rats that acute ethanol administration, via a single intraperitoneal injection, selectively impairs the memory of certain spatial tasks. It is unknown whether these same results can be produced in the C57BL/6J mouse strain. Male C57BL/6J mice were trained in a spatial task in the Morris water maze. After training, an ethanol test was administered in which each mouse was given an injection of one of four randomly assigned doses: ethanol, at a dose of 1.25, 1.75, or 2.25 g/kg, or a saline control dose that remained constant at 1.75 g/kg. Thirty minutes after injection, the mice were given the spatial task. Next, the same mice were given training for a nonspatial task in the Morris water maze. After training, another ethanol test was administered. Again, the mice were randomly assigned one of the aforementioned doses. Thirty minutes after injections, the mice were given the nonspatial task. Results from Study 1, by using latency, showed that acute ethanol administration selectively impaired spatial memory (P<.05) at 1.75 and 2.25 g/kg doses, yet it failed to significantly impair nonspatial memory except at the 2.25 g/kg dose. Results from Study 2, by using path lengths, showed similar effects, in that acute ethanol administration selectively impaired spatial memory (P<.05) at the 2.25 g/kg dose, yet it failed to impair nonspatial memory at any dose. These findings demonstrate that acute ethanol administration selectively impairs spatial memory in C57BL/6J mice.

Animals↗

Interrogating rodents regarding their object and spatial memory.

Today, neuroscientists have access to a host of advanced techniques -- ranging from targeted genetic interventions to brain imaging -- that are rapidly providing new insights. Ultimately, however, memory must be inferred from its behavioral read-out. Thus, to fully utilize the advanced technologies available today, we must select the most appropriate behavioral procedures from those currently available, or else devise novel behavioral techniques to meet a specific demand. If we merely use standard tests of memory in a non-optimal way, we risk collecting incomplete information and reaching erroneous conclusions. Relevant to these issues, there have been substantial developments in the methods used to evaluate two of the most frequently studied forms of memory in the rodent -- recognition memory and spatial memory.

Animals↗

Cortical control of spatial memory in humans: the visuooculomotor model.

We review current knowledge of the cortical control of spatial memory, studied using visuooculomotor paradigms. Spatial memory is an essential cognitive process that can be involved in preparing motor responses. Our knowledge of spatial memory in humans recently has progressed thanks to the use of ocular saccades as a convenient model of motor behavior. Accuracy of memory-guided saccades, made to the remembered locations of visual targets, is a reflection of spatial memory. For the performance of memory-guided saccades with brief delays (up to 15-20 seconds), that is, involving short-term spatial memory, lesion studies have shown that the posterior parietal cortex, the dorsolateral prefrontal cortex, and the frontal eye field play significant roles. Studies of memory-guided saccades using transcranial magnetic stimulation have suggested that the right posterior parietal cortex is involved at the initial stage (<300 milliseconds) of visuospatial integration, whereas the dorsolateral prefrontal cortex in both hemispheres controls the following phase of short-term memorization, the frontal eye field mainly serving to trigger saccades. The new concept of a medium-term spatial memory has emerged from a behavioral study of memory-guided saccades in normal subjects, showing a paradoxical spontaneous improvement of spatial memory after delays of approximately 20 seconds. Lesion studies have shown that the parahippocampal cortex could specifically control this medium-term spatial memory. Last, different experimental and clinical arguments suggest that, after a few minutes, the hippocampal formation finally takes over the control of spatial memory for long-term spatial memorization. Therefore, spatial memory involved in the memorization of visual items could be successively controlled by the dorsolateral prefrontal cortex (short-term spatial memory), the parahippocampal cortex (medium-term spatial memory), and the hippocampal formation (long-term spatial memory), depending on specific periods of times. The applicability of this simple visuooculomotor model of spatial memory to other types of stimuli and general motoricity has yet to be confirmed.

Animals↗

Spatial memory, recognition memory, and the hippocampus.

There is wide agreement that spatial memory is dependent on the integrity of the hippocampus, but the importance of the hippocampus for nonspatial tasks, including tasks of object recognition memory is not as clear. We examined the relationship between hippocampal lesion size and both spatial memory and object recognition memory in rats. Spatial memory was impaired after bilateral dorsal hippocampal lesions that encompassed 30-50% total volume, and as lesion size increased from 50% to approximately 100% of total hippocampal volume, performance was similarly impaired. In contrast, object recognition was intact after dorsal hippocampal lesions that damaged 50-75% of total hippocampal volume and was impaired only after larger lesions that encompassed 75-100% of hippocampal volume. Last, ventral hippocampal lesions that encompassed approximately 50% of total hippocampal volume impaired spatial memory but did not affect object recognition memory. These findings show that the hippocampus is important for both spatial memory and recognition memory. However, spatial memory performance requires more hippocampal tissue than does recognition memory.

Animals↗

Field experiments on duration and precision of grey and red squirrel spatial memory

Field experiments on squirrel spatial memory under naturalistic conditions showed that grey squirrels, Sciurus carolinensisare capable of relocating precise spatial goals using short range visual cues. These goals were in the form of buried food, similar to natural cache sites, and were relocated to within 5 cm in 62.5% of all attempts after a retention interval of 20 days. Some recall could be demonstrated after more protracted retention intervals (43 and 62 days). These results suggest that grey squirrels' spatial memory is accurate enough to support a successful retrieval strategy. Application of one of the same methods to a population of red squirrels, Sciurus vulgariswhich is not as reliant on stored food, suggested that their spatial memory is less long lasting as predicted by the adaptive specialization hypothesis of cognitive function.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Journal Article↗

Individual difference and contextual variables influence spatial memory in younger and older adults.

This study examined the influence of individual difference and contextual variables on the magnitude of age differences in memory for spatial location. Younger adults and 2 samples of older adults that differed in educational attainment, verbal intelligence, and working memory ability were compared. Ss studied and later recreated an arrangement of small objects that were placed on a plain map or a visually distinctive model. The objects were either unrelated or categorically related items. The results indicated that distinctive context enhanced spatial memory, and the magnitude of the benefit was generally comparable across age groups and stimulus sets. Hierarchical regression analyses confirmed that working memory resources accounted for a sizable proportion of age-related variance in memory for spatial location. The implications of these results for current views on age-related differences in memory for spatial location are discussed.

Adult↗

Long-term continuous, but not daily, environmental enrichment reduces spatial memory decline in aged male mice.

Although environmental enrichment improves spatial memory and alters synaptic plasticity in aged rodents, it is unclear whether all types of enrichment treatments yield similar benefits. The present study examined the effects in aged male mice of three types of enrichment on spatial memory in Morris water maze and radial arm maze tasks, and on levels of the presynaptic protein synaptophysin in several brain regions. Non-enriched young and aged males were compared with males exposed to one of the following treatments for 10 weeks: 5 min of daily handling, 3 h of daily basic enrichment, or 24 h of continuous complex enrichment. Young controls outperformed aged controls in both tasks. Neither daily handling nor daily enrichment affected spatial memory or synaptophysin levels. In contrast, continuous enrichment significantly reduced age-related spatial memory decline in both tasks, such that this group was statistically indistinguishable from young controls in most measures of performance. Continuously enriched mice were also significantly better than other aged mice in several spatial memory measures. Despite these improvements, synaptophysin levels in the continuous enrichment group were significantly lower than those of young and aged controls in the frontoparietal cortex, hippocampus, and striatum, suggesting a negative relationship between synaptophysin levels and spatial memory in aged males. These data demonstrate that different types of enrichment in aged male mice have disparate effects on spatial memory, and that the relationship between enrichment-induced changes in synaptophysin levels and spatial memory in aged males differs from that we have previously reported in aged female mice.

Aging↗

Ethanol-induced impairment of spatial memory and brain matrix metalloproteinases.

The formation of spatial memory appears to be dependent upon an intact hippocampus capable of the specific biochemical changes associated with synaptic remodeling. Hippocampal damage results in the disruption of synaptic remodeling and the acquisition of spatial memory tasks. Ethanol also disrupts normal hippocampal functioning and spatial memory. The present investigation established a dose-response relationship between ethanol treatment and impairment of spatial memory as measured using the circular water maze task. Intraperitoneal ethanol doses of 1.5 and 2 g/kg significantly increased the latency and distance swam to find the submerged pedestal as compared with a 1 g/kg dose, and 0.15 M NaCl vehicle control treatments. On days 2, 4, and 6 of acquisition animals were sacrificed and brain tissues were retained from the hippocampus, prefrontal neocortex, and cerebellum for measurement of matrix metalloproteinases (MMPs). The results indicated that ethanol treatment interfered with MMP-9, but not MMP-2, activity in the hippocampus, and to a lesser degree in the prefrontal cortex. No changes in the cerebellum were measured. Elevations in MMP activity appear to be a prerequisite to reconfiguration of extracellular matrix cell adhesion molecules thought to be important in the process of synaptic plasticity, which in turn appears to be necessary for memory consolidation. Thus, ethanol-induced impairment in the acquisition of spatial memory tasks may, in part, be due to disruption of brain MMP activity.

Animals↗

Involvement of the anterior cingulate cortex in the expression of remote spatial memory.

Although the hippocampus plays a crucial role in the formation of spatial memories, as these memories mature they may become additionally (or even exclusively) dependent on extrahippocampal structures. However, the identity of these extrahippocampal structures that support remote spatial memory is currently not known. Using a Morris water-maze task, we show that the anterior cingulate cortex (ACC) plays a key role in the expression of remote spatial memories in mice. To first evaluate whether the ACC is activated after the recall of spatial memory, we examined the expression of the immediate early gene, c-fos, in the ACC. Fos expression was elevated after expression of a remote (1 month old), but not recent (1 d old), water-maze memory, suggesting that ACC plays an increasingly important role as a function of time. Consistent with the gene expression data, targeted pharmacological inactivation of the ACC with the sodium channel blocker lidocaine blocked expression of remote, but spared recent, spatial memory. In contrast, inactivation of the dorsal hippocampus disrupted expression of spatial memory, regardless of its age. We further showed that inactivation of the ACC blocked expression of remote spatial memory in two different mouse strains, after training with either a hidden or visible platform in a constant location, and using the AMPA receptor antagonist CNQX. Together, our data provide evidence that circuits supporting spatial memory are reorganized in a time-dependent manner, and establish that activity in neurons intrinsic to the ACC is critical for processing remote spatial memories.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

Episodic spatial memory in adulthood.

Two experiments examined age-related differences in memory for spatial location information in a museum exhibit (Experiment 1) and in a secretarial office (Experiment 2). In Experiment 1, subjects were the visitors to the exhibit (N = 302, 15-74 years of age), and memory was assessed using a map test. In Experiment 2, subjects were 64 young adults (M = 21.2 years) and 32 older adults (M = 71.2 years), and memory was assessed using both a map test and a relocation test. The relocation test required subjects to replace the to-be-remembered targets where they appeared at study. Experiment 1 showed an age-related decline in spatial memory performance, and it placed the onset of this decline in the sixth decade of life. Experiment 2 showed an age-related decline on both tests, but age effects were smaller on the relocation test than on the map test, and when subjects knew that spatial memory would be tested than when they were not informed.

Adolescent↗

Sites of neocortical reorganization critical for remote spatial memory.

The hippocampus is crucial for spatial memory formation, yet it does not store long-lasting memories. By combining functional brain imaging and region-specific neuronal inactivation in mice, we identified prefrontal and anterior cingulate cortices as critical for storage and retrieval of remote spatial memories [correction]. Imaging of activity-dependent genes also revealed an involvement of parietal and retrosplenial cortices during consolidation of remote memory. Long-term memory storage within some of these neocortical regions was accompanied by structural changes including synaptogenesis and laminar reorganization, concomitant with a functional disengagement of the hippocampus and posterior cingulate cortex [correction]. Thus, consolidation of spatial memory requires a time-dependent hippocampal-cortical dialogue, ultimately enabling widespread cortical networks to mediate effortful recall and use of cortically stored remote memories independently.

Animals↗

Acute dose of MDMA (75 mg) impairs spatial memory for location but leaves contextual processing of visuospatial information unaffected.

RATIONALE: Research concerning spatial memory in 3,4-methylenedioxymethamphetamine (MDMA) users has presented conflicting results showing either the presence or absence of spatial memory deficits. Two factors may have confounded results in abstinent users: memory task characteristics and polydrug use. OBJECTIVES: The present study aims to assess whether a single dose of MDMA affects spatial memory performance during intoxication and withdrawal phase and whether spatial memory performance after MDMA is task dependent. MATERIALS AND METHODS: Eighteen recreational MDMA users participated in a double-blind, placebo-controlled, three-way crossover design. They were treated with placebo, MDMA 75 mg, and methylphenidate 20 mg. Memory tests were conducted between 1.5 and 2 h (intoxication phase) and between 25.5 and 26 h (withdrawal phase) post-dosing. Two spatial memory tasks of varying complexity were used that required either storage of stimulus location alone (spatial memory task) or memory for location as well as processing of content or contextual information (change blindness task). RESULTS: After a single dose of MDMA, the subjects made larger localization errors and responded faster compared to placebo in the simple spatial memory task during intoxication phase. Inaccuracy was not due to increased response speed, as determined by regression analysis. Performance in the change blindness task was not affected by MDMA. Methylphenidate did not affect performance on any of the tasks. CONCLUSION: It is concluded that a single dose of MDMA impairs spatial memory for location but leaves processing of contextual information intact.

Adult↗

Spatial memory deficits in patients after unilateral selective amygdalohippocampectomy.

The present study investigated the differential involvement of the right and left hippocampus in various forms of spatial memory: spatial search, positional memory versus object-location binding, and coordinate versus categorical processing. Twenty-five epilepsy patients with selective amygdalohippocampectomy were examined using a sensitive computer paradigm to measure these spatial memory aspects. The patients' performance was compared to a group of thirty healthy controls. The results show that the left amygdalohippocampectomy group performed poorly on the ability to bind together object information to coordinate spatial locations. In turn, the right amygdalohippocampectomy group was impaired in coordinate positional memory. Both patient groups were unimpaired on the spatial search task. These findings are discussed focusing on the "binding device" hypothesis in combination with the cognitive map theory.

Adult↗