Memory Retrieval Deficits Research Articles

“Cat-gras” delusion: a unique misidentification syndrome and a novel explanation

ABSRACTCapgras syndrome is a distressing delusion found in a variety of neurological and psychiatric diseases where a patient believes that a family member, friend, or loved one has been replaced by an imposter. Patients recognize the physical resemblance of a familiar acquaintance but feel that the identity of that person is no longer the same. Here we describe a 73-year-old male with right posterior frontal and bilateral anterior-medial frontal damage from prior brain trauma with a similar delusion of an imposter replacing his pet cat. Misidentification syndromes for animals, as opposed to humans, have been rarely reported. Neuropsychological testing showed deficits in executive processing and memory retrieval with prominent intrusions and false positive responses. The delusional belief content in Capgras syndrome has been hypothesized to result from loss of an emotional or autonomic response to familiar stimuli, from theory of mind deficits, or from loss of self-environment distinctions. We instead propose that Capgras delusions result from a dysfunction in linking external stimuli with retrieved internal autobiographical memories pertaining to that object. This leads to an erroneously learned identity that persists as a specific delusional belief.

Influences of Long-Term Memory-Guided Attention and Stimulus-Guided Attention on Visuospatial Representations within Human Intraparietal Sulcus.

The human parietal lobe contains multiple maps of the external world that spatially guide perception, action, and cognition. Maps in each cerebral hemisphere code information from the opposite side of space, not from the same side, and the two hemispheres are symmetric. Paradoxically, damage to specific parietal regions that lack spatial maps can cause patients to ignore half of space (hemispatial neglect syndrome), but only for right (not left) hemisphere damage. Conversely, the left parietal cortex has been linked to retrieval of vivid memories regardless of space. Here, we investigate possible underlying mechanisms in healthy individuals. We demonstrate two forms of dynamic changes in parietal spatial representations: an asymmetric one for stimulus-guided attention and a symmetric one for long-term memory-guided attention.

Ecstasy exposure & gender: examining components of verbal memory functioning.

ObjectiveStudies have demonstrated verbal memory deficits associated with past year ecstasy use, although specific underlying components of these deficits are less understood. Further, prior research suggests potential gender differences in ecstasy-induced serotonergic changes. Therefore, the current study investigated whether gender moderated the relationship between ecstasy exposure and components of verbal memory after controlling for polydrug use and confounding variables.MethodData were collected from 65 polydrug users with a wide range of ecstasy exposure (ages 18–35; 48 ecstasy and 17 marijuana users; 0–2310 ecstasy tablets). Participants completed a verbal learning and memory task, psychological questionnaires, and a drug use interview.ResultsIncreased past year ecstasy exposure predicted poorer short and long delayed free and cued recalls, retention, and recall discrimination. Male ecstasy users were more susceptible to dose-dependent deficits in retention than female users.ConclusionPast year ecstasy consumption was associated with verbal memory retrieval, retention, and discrimination deficits in a dose-dependent manner in a sample of healthy young adult polydrug users. Male ecstasy users were at particular risk for deficits in retention following a long delay. Gender difference may be reflective of different patterns of polydrug use as well as increased hippocampal sensitivity. Future research examining neuronal correlates of verbal memory deficits in ecstasy users are needed.

Abnormal emotional learning in a rat model of autism exposed to valproic acid in utero.

Autism Spectrum Disorders (ASD) are complex neurodevelopmental disorders characterized by repetitive behavior and impaired social communication and interactions. Apart from these core symptoms, a significant number of ASD individuals display higher levels of anxiety and some ASD individuals exhibit impaired emotional learning. We therefore sought to further examine anxiety and emotional learning in an environmentally induced animal model of ASD that utilizes the administration of the known teratogen, valproic acid (VPA) during gestation. Specifically we exposed dams to one of two different doses of VPA (500 and 600 mg/kg) or vehicle on day 12.5 of gestation and examined the resultant progeny. Our data indicate that animals exposed to VPA in utero exhibit enhanced anxiety in the open field test and normal object recognition memory compared to control animals. Animals exposed to 500 mg/kg of VPA displayed normal acquisition of auditory fear conditioning, and exhibited reduced extinction of fear memory and normal litter survival rates as compared to control animals. We observed that animals exposed to 600 mg/kg of VPA exhibited a significant reduction in the acquisition of fear conditioning, a significant reduction in social interaction and a significant reduction in litter survival rates as compared to control animals. VPA (600 mg/kg) exposed animals exhibited similar shock sensitivity and hearing as compared to control animals indicating the fear conditioning deficit observed in these animals was not likely due to sensory deficits, but rather due to deficits in learning or memory retrieval. In conclusion, considering that progeny from dams exposed to rather similar doses of VPA exhibit striking differences in emotional learning, the VPA model may serve as a useful tool to explore the molecular and cellular mechanisms that contribute to not only ASD, but also emotional learning.

The hippocampo-amygdala control of contextual fear expression is affected in a model of intellectual disability.

The process of learning mainly depends on the ability to store new information, while the ability to retrieve this information and express appropriate behaviors are also crucial for the adaptation of individuals to environmental cues. Thereby, all three components contribute to the cognitive fitness of an individual. While a lack of behavioral adaptation is a recurrent trait of intellectually disabled patients, discriminating between memory formation, memory retrieval or behavioral expression deficits is not easy to establish. Here, we report some deficits in contextual fear behavior in knockout mice for the intellectual disability gene Il1rapl1. Functional in vivo experiments revealed that the lack of conditioned response resulted from a local inhibitory to excitatory (I/E) imbalance in basolateral amygdala (BLA) consecutive to a loss of excitatory drive onto BLA principal cells by caudal hippocampus axonal projections. A normalization of the fear behavior was obtained in adult mutant mice following opsin-based in vivo synaptic priming of hippocampo-BLA synapses in adult il1rapl1 knockout mice, indicating that synaptic efficacy at hippocampo-BLA projections is crucial for contextual fear memory expression. Importantly, because this restoration was obtained after the learning phase, our results suggest that some of the genetically encoded cognitive deficits in humans may originate from a lack of restitution of genuinely formed memories rather than an exclusive inability to store new memories.

A preliminary study of gender differences in autobiographical memory in children with an autism spectrum disorder.

Autobiographical memory was assessed in 24 children (12 male, 12 female, aged between 8 and 16 years) with autism spectrum disorder (ASD) and a comparison group of 24 typically developing (TD) children matched for age, IQ, gender and receptive language. Results suggested that a deficit in specific memory retrieval in the ASD group was more characteristic of male participants. Females in both the TD and ASD groups generated more detailed and emotional memories than males. They also demonstrated superior verbal fluency scores; verbal fluency and autobiographical memory cueing task performance were significantly positively correlated in females. Results are discussed in light of recent research suggesting gender differences in the phenotype of ASD.

Prenatal stress decreases spatial learning and memory retrieval of the adult male offspring of rats

IntroductionEarly life or prenatal stress induces many lifelong, mostly cognitive, homeostatic alterations in the behavior of the offspring. PurposeWe investigated the effect of heterogeneous sequential stress (HSS) at three separate periods, before and during the first and second half of pregnancies on spatial learning and memory retrieval of adult male offspring. MethodHSS is composed of several stressors, each in a day, during nine consecutive days including; restraint, swimming, isolation, and water and food deprivation on Wistar rats. The offspring were studied in a Morris water maze (MWM) apparatus to explore the latency, distance, proximity and target to opposite area as measures of learning and memory. Serum corticosterone was measured as a criterion of stress application. ResultsHSS increased blood corticosterone in dams of PS2 (Pregnancy Stress second half), and also in adult male offspring from BPS (Before Pregnancy Stress) and PS1 (Pregnancy Stress first half) groups. The weight of the offspring decreased in the PS1 and PS2 groups. While distance traveled and latency to locate the hidden platform were increased in BPS and PS1 acquisition trials, swimming speed was unchanged during the acquisition and retrieval tests. Moreover, time to platform location was increased in BPS and PS1 during retention tests. While control rats spent more time in the target quadrant, stressed animals spent a longer duration in the opposite quadrant. Furthermore, proximity measure was increased in all stress treated rats. ConclusionIt is concluded that prenatal stress, around the beginning of the pregnancy, increases corticosterone in adult male offspring, which might be the basis for spatial learning and memory retrieval deficits in this study.

Multifunctional Effects of Mangosteen Pericarp on Cognition in C57BL/6J and Triple Transgenic Alzheimer's Mice.

Mangosteen- (Garcinia mangostana-) based nutraceutical compounds have long been reported to possess multiple health-promoting properties. The current study investigated whether mangosteen pericarp (MP) could attenuate cognitive dysfunction. First, we found that treatment with MP significantly reduced the cell death and increased the brain-derived neurotrophic factor (BDNF) level in an organotypic hippocampal slice culture (OHSC). We then investigated the effects of age and MP diet on the cognitive function of male C57BL/6J (B6) mice. After 8-month dietary supplementation, the MP diet (5000 ppm) significantly attenuated the cognitive impairment associated with anti-inflammation, increasing BDNF level and decreasing p-tau (phospho-tau S202) in older B6 mice. We further applied MP dietary supplementation to triple transgenic Alzheimer's disease (3×Tg-AD) mice from 5 to 13 months old. The MP diet exerted neuroprotective, antioxidative, and anti-inflammatory effects and reduced the Aβ deposition and p-tau (S202/S262) levels in the hippocampus of 3×Tg-AD mice, which might further attenuate the deficit in spatial memory retrieval. Thus, these results revealed that the multifunctional properties of MP might offer a promising supplementary diet to attenuate cognitive dysfunction in AD.

Executive dysfunction and autobiographical memory retrieval in recovered depressed women

Background and objectivesDepressed individuals have difficulty remembering specific autobiographical events. These deficits often persist after recovery of mood symptoms, but the mechanisms underlying impaired memory specificity in recovered depressed individuals remain unclear. Here, we sought to examine whether performance on two cognitive measures might be related to deficits in autobiographical memory retrieval in individuals with a history of depression. MethodsTwenty-four recovered depressed women (12 with more than one previous episode) and 24 never depressed women completed two cognitive measures (Digit Span and a Number Generation Task) and tests of autobiographical memory recall. ResultsOverall, the recovered depressed women did not show deficits in autobiographical retrieval. However, those with more than one previous episode had impaired retrieval of categorical autobiographical memories. Moreover, depression history moderated the relationship between Digit Span and retrieval of categoric autobiographical memories such that within the whole recovered depressed group (but not the never depressed group), those with lower Digit Span also had poorer retrieval of categorical autobiographical memories. LimitationsOur sample size was small and included only women. Moreover, order effects may have been a significant factor. ConclusionsThese findings support the notion that working memory is an important factor in impairing autobiographical memory in those who have recovered from depression, but suggest a complex relationship with autobiographical recall.

Specific cerebellar grey matter volume loss is predictive for episodic memory retrieval deficits in early Alzheimer's disease

Alzheimer's & DementiaVolume 9, Issue 4S_Part_3 p. P115-P115 AbstractFree Access IC-P-207: Specific cerebellar grey matter volume loss is predictive for episodic memory retrieval deficits in early Alzheimer's disease Heidi Jacobs, Heidi Jacobs Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorEd H.B.M. Gronenschild, Ed H.B.M. Gronenschild Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorLies Clerx, Lies Clerx Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorPauline Aalten, Pauline Aalten Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorFrans R.J. Verhey, Frans R.J. Verhey Maastricht University, Maastricht, the NetherlandsSearch for more papers by this author Heidi Jacobs, Heidi Jacobs Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorEd H.B.M. Gronenschild, Ed H.B.M. Gronenschild Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorLies Clerx, Lies Clerx Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorPauline Aalten, Pauline Aalten Maastricht University, Maastricht, the NetherlandsSearch for more papers by this authorFrans R.J. Verhey, Frans R.J. Verhey Maastricht University, Maastricht, the NetherlandsSearch for more papers by this author First published: 01 July 2013 https://doi.org/10.1016/j.jalz.2013.05.1780AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume9, Issue4S_Part_3Alzheimer's Association International Conference 2013July 2013Pages P115-P115 RelatedInformation

Altered brain structure in Chinese dyslexic children

Due to the logographic nature of the writing system, learning to read Chinese places heavy demands on encoding of orthographic forms through rote memorization. Moreover, phonology has to often be retrieved from memory during reading because of the inconsistent mapping between characters and their pronunciations. Using optimized voxel-based morphometry, we examined differences in volumetrics between children with reading disability (RD, 10–12 years old) and age-matched typically developing (TD) children. Our study shows reduced gray matter volume (GMV) for RD in right inferior occipital gyrus and left inferior frontal gyrus, consistent with previous studies suggesting that Chinese dyslexics have deficits in orthographic and phonological processing. The deficit in phonological processing was further supported by reductions in white matter volumes (WMV) in left precentral gyrus. Greater deficits in ortho-phonological processing may be associated with semantic compensation, as lower skill RD children showed greater GMV in anterior temporal cortex, even though as a group they showed less GMV in this region compared to TD. Perhaps most interestingly, we showed reduced GMV in bilateral ventromedial prefrontal cortices (vmPFC) and this was correlated with reductions in WMV within vmPFC, suggesting that RD have deficits in memory retrieval. Moreover, these GMV alterations in vmPFC for the RD were correlated with alterations in right parahippocampal gyrus, which also showed a reduced GMV, suggesting that RD have a correlated deficit in memory encoding. Our results are consistent with previous studies suggesting that Chinese dyslexics have deficits in visuo-orthographic and phonological processing, but our study importantly suggests deficits in memory encoding and retrieval, perhaps due to the unique demands of the Chinese writing system.

Neurobiological Dissociation of Retrieval and Reconsolidation of Cocaine-Associated Memory

Drug use is provoked by the presentation of drug-associated cues, even following long periods of abstinence. Disruption of these learned associations would therefore limit relapse susceptibility. Drug-associated memories are susceptible to long-term disruption during retrieval and shortly after, during memory reconsolidation. Recent evidence reveals that retrieval and reconsolidation are dependent on β-adrenergic receptor (β-AR) activation. Despite this, whether retrieval and reconsolidation are dependent on identical or distinct neural mechanisms is unknown. The prelimbic medial prefrontal cortex (PL-mPFC) and basolateral amygdala (BLA) have been implicated in the expression and reconsolidation of associative memories. Therefore, we investigated the necessity of β-AR activation within the PL-mPFC and BLA for cocaine-associated memory retrieval and reconsolidation in rats. Before or immediately after a cocaine-induced conditioned place preference (CPP) retrieval trial, β-AR antagonists were infused into the PL-mPFC or BLA, followed by daily testing. PL-mPFC infusions before, but not after, a CPP trial disrupted CPP memory retrieval and induced a persistent deficit in retrieval during subsequent trials. In contrast, BLA β-AR blockade had no effect on initial CPP memory retrieval, but prevented CPP expression during subsequent trials indicative of reconsolidation disruption. Our results reveal a distinct dissociation between the neural mechanisms required for cocaine-associated memory retrieval and reconsolidation. Using patch-clamp electrophysiology, we also show that application of a β-AR antagonist prevents norepinephrine-induced potentiation of PL-mPFC pyramidal cell and γ-aminobutyric-acid (GABA) interneuron excitability. Thus, targeted β-AR blockade could induce long-term deficits in drug-associated memory retrieval by reducing neuronal excitability, providing a novel method of preventing cue-elicited drug seeking and relapse.

Early neuropsychological discriminants for Lewy body disease: an autopsy series

ObjectiveTo determine which neuropsychological test measures and which symptoms at presentation might best differentiate dementia with Lewy bodies (DLB) from Alzheimer's disease (AD).MethodsCases were from the Columbia University Alzheimer's Disease...

A Preliminary Study of Functional Brain Activation among Marijuana Users during Performance of a Virtual Water Maze Task

Numerous studies have reported neurocognitive impairments associated with chronic marijuana use. Given that the hippocampus contains a high density of cannabinoid receptors, hippocampal-mediated cognitive functions, including visuospatial memory, may have increased vulnerability to chronic marijuana use. Thus, the current study examined brain activation during the performance of a virtual analogue of the classic Morris water maze task in 10 chronic marijuana (MJ) users compared to 18 nonusing (NU) comparison subjects. Imaging data were acquired using blood oxygen level-dependent (BOLD) functional MRI at 3.0 Tesla during retrieval (hidden platform) and motor control (visible platform) conditions. While task performance on learning trials was similar between groups, MJ users demonstrated a deficit in memory retrieval. For BOLD fMRI data, NU subjects exhibited greater activation in the right parahippocampal gyrus and cingulate gyrus compared to the MJ group for the Retrieval-Motor Control contrast (NU > MJ). These findings suggest that hypoactivation in MJ users may be due to differences in the efficient utilization of neuronal resources during the retrieval of memory. Given the paucity of data on visuospatial memory function in MJ users, these findings may help elucidate the neurobiological effects of marijuana on brain activation during memory retrieval.

Stress-Induced Memory Retrieval Impairments: Different Time-Course Involvement of Corticosterone and Glucocorticoid Receptors in Dorsal and Ventral Hippocampus

The present study was aimed at determining the relative contribution of the dorsal (DH) and ventral (VH) hippocampus in stress-induced memory retrieval impairments. Thus, we studied the temporal involvement of corticosterone and its receptors, i.e. mineralocorticoid (MR) and glucocorticoid (GR) in the DH and VH, in relation with the time-course evolution of stress-induced memory retrieval impairments. In a first experiment, double microdialysis allowed showing on the same animal that an acute stress (electric footshocks) induced an earlier corticosterone rise in the DH (15–60 min post-stress) and then in the VH (90–105 min post-stress). The return to baseline was faster in the DH (105 min) than in the VH (120 min). Memory deficits assessed by delayed alternation occurred at 15-, 60-, and 105-min delays after stress and were closely related to the kinetic of corticosterone rises within the DH and VH. In a second experiment, the GR antagonist RU-38486 and the MR antagonist RU-28318 were administered in the DH or VH 15 min before stress. RU-38486 restored memory at 60 but not at 105 min post-stress delays in the DH, whereas the opposite pattern was observed in the VH. By contrast, RU-28318 had no effect on memory impairments at both the 60- and 105-min post-stress delays, showing that MR receptors are not involved at these delays. However, RU-28318 administered in the DH restored memory when administered at a shorter post-stress delay (15 min). Overall, our data are first to evidence that stress induces a functional switch from the DH to VH via different corticosterone time-course evolutions in these areas and the sequential GR receptors involvement in the DH and then in the VH, as regards the persistence of stress-induced memory retrieval deficits over time.

Neuropsychological performance differences between two groups of probable-AD patients from different areas of Brazil.

During normal aging there are some cognitive and behavioral changes similar to those observed in a transitional state or mild cognitive impairment (MCI) and early onset dementia, making it challenging for health care professionals to reach an accurate and reliable diagnosis.ObjectiveThe current study examined the performance of two different groups of patients diagnosed with probable Alzheimer's disease (AD) on a neuropsychological test battery.MethodsTwenty-two AD patients from Brasília-DF (AD1) and thirty-four AD patients from Palmas-TO, northern Brazil (AD2), were selected and a short neuropsychological battery administered. To verify the reliability of these previous diagnoses of AD, both groups of patients were compared with a group of healthy controls.ResultsAD patients showed cognitive deficit but scores were lower for the AD2 group compared with the AD1 group considering the cut-off point. Notably, patients from the AD1 group were older (p=0.004) and had less formal education (p<0.001) than those from the AD2 group. Comparing different cognitive domains between AD groups, post hoc analysis showed that the AD1 group was characterized by deficits in episodic memory retrieval (p<0.001), semantic memory (p<0.001) and verbal fluency (p<0.001). In contrast, the AD2 group showed lower scores in attention (p=0.007), executive functioning (p<0.001) and working memory (p<0.001).ConclusionThis pattern suggests that the Palma group of patients had a neuropsychological profile that was inconsistent with AD. Although the results of this study have important clinical implications, the effects of age, education, and gender on cognitive performance should be explored further.

A longitudinal study of processes predicting the specificity of autobiographical memory in the adolescent offspring of depressed parents

Deficits in specific autobiographical memory retrieval are closely associated with depression. The ability to retrieve specific autobiographical memories develops throughout childhood and adolescence and is associated with adolescent depression within and across time. Studying young samples before they first experience depression provides an approach for testing processes that underlie reduced autobiographical memory specificity. This study is the first to examine the longitudinal association of rumination and executive function with autobiographical memory specificity in a sample of adolescents at elevated risk for future depression. A total of 259 adolescents (aged between 10 and 18 years) completed the Autobiographical Memory Test at baseline and 1-year follow-up. Measures of rumination, executive function, and depressive symptoms were obtained at baseline. The interaction between rumination and executive function predicted autobiographical memory specificity over time. Whereas rumination in the context of low executive function predicted reduced specificity, this was not the case in the context of high executive function. The interaction between rumination and executive function was independent of the effects of age, gender, IQ, baseline levels of memory specificity, and depressive symptoms.

Event-related EEG oscillations to semantically unrelated words in normal and learning disabled children

Learning disabilities (LD) are one of the most frequent problems for elementary school-aged children. In this paper, event-related EEG oscillations to semantically related and unrelated pairs of words were studied in a group of 18 children with LD not otherwise specified (LD-NOS) and in 16 children with normal academic achievement. We propose that EEG oscillations may be different in LD NOS children versus normal control children that may explain some of the deficits observed in the LD-NOS group. The EEGs were recorded using the 10/20 system. EEG segments were edited by visual inspection 1000ms before and after the stimulus, and only correct responses were considered in the analysis. Time–frequency (1–50Hz) topographic maps were obtained for the increases and decreases of power after the event with respect to the pre-stimulus average values. Significant differences between groups were observed in the behavioral responses. LD-NOS children show less number of correct responses and more omissions and false alarms than the control group. The event-induced EEG responses showed significant differences between groups. The control group showed greater power increases in the frequencies 1–6Hz than the LD-NOS group from 300 to 700ms. These differences were mainly observed in frontal regions, both to related and non-related words. This was interpreted as a deficit in attention, both to internal and external events, deficits in activation of working memory and deficits in encoding and memory retrieval in the LD-NOS children. Differences between groups were also observed in the suppression of alpha and beta rhythms in the occipital regions to related words in frequencies between 8 and 17Hz from 450 to 750ms. LD-NOS children showed shorter durations of the decreases in power than the control group. These results suggest also deficits in attention and memory retrieval. It may be concluded that LD-NOS children showed physiological differences from normal children that may explain their cognitive deficiencies.

Encoding, memory, and transcoding deficits in Childhood Apraxia of Speech

A central question in Childhood Apraxia of Speech (CAS) is whether the core phenotype is limited to transcoding (planning/programming) deficits or if speakers with CAS also have deficits in auditory-perceptual encoding (representational) and/or memory (storage and retrieval of representations) processes. We addressed this and other questions using responses to the Syllable Repetition Task (SRT) [Shriberg, L. D., Lohmeier, H. L., Campbell, T. F., Dollaghan, C. A., Green, J. R., & Moore, C. A. (2009). A nonword repetition task for speakers with misarticulations: The syllable repetition task (SRT). Journal of Speech, Language, and Hearing Research, 52, 1189–1212]. The SRT was administered to 369 individuals in four groups: (a) typical speech–language (119), (b) speech delay–typical language (140), (c) speech delay–language impairment (70), and (d) idiopathic or neurogenetic CAS (40). CAS participants had significantly lower SRT competence, encoding, memory, and transcoding scores than controls. They were 8.3 times more likely than controls to have SRT transcoding scores below 80%. We conclude that speakers with CAS have speech processing deficits in encoding, memory, and transcoding. The SRT currently has moderate diagnostic accuracy to identify transcoding deficits, the signature feature of CAS.

5-HT6 receptor blockade differentially affects scopolamine-induced deficits of working memory, recognition memory and aversive learning in mice

Blockade of 5-HT6 receptors (5-HT6R) is known to improve cognitive performances in the rodent. This improvement has been hypothesized to be the result, at least in part, of a modulation of the cholinergic neurotransmission. We assessed the effects of 5-HT6R blockade on selected types of memory relevant to functional deficits of ageing and neurodegenerative diseases, in mice that present a scopolamine-induced cholinergic disruption of memory. Following the selection of an adequate dose of scopolamine to induce cognitive deficits, we have studied the effects of the selective 5-HT6R antagonist SB-271046, alone or in combination with scopolamine, on working memory (spontaneous alternation task in the T-maze), recognition memory (place recognition) and aversive learning (passive avoidance). SB-271046 alone failed to affect working memory, recognition memory and aversive learning performances. In contrast, SB-271046 was able to reverse the scopolamine-induced deficits in working memory (only at 30 mg kg⁻¹) and those of acquisition and retrieval of aversive learning (dose-dependent effect); scopolamine-induced deficits in episodic-like memory (acquisition and retrieval) were partially counteracted by 5-HT6R blockade. The modulation between 5-HT6R and the cholinergic system appears to be predominant for working memory and aversive learning, but not for other types of memory (i.e. episodic-like memory). Interactions between 5-HT6R and alternative neurotransmission systems (i.e. glutamatergic system) should be further studied. The respective involvement of these interactions in the memory disorders related to ageing and neurodegenerative diseases is of pivotal importance regarding the possible use of 5-HT6R antagonists in the treatment of memory disorders in humans.