| 1. |
- Tribukait, Arne
(författare)
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Human vestibular memory studied via measurement of the subjective horizontal during gondola centrifugation
- 2003
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Ingår i: Neurobiology of Learning and Memory. - 1074-7427 .- 1095-9564. ; 80:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of the subjective visual horizontal (SVH) were made in a large swing-out gondola centrifuge. Rotation of the centrifuge was anti-clockwise, as seen from above. Test subjects were seated upright in the gondola, facing forwards. In front of the subject, at a straight-ahead eye-level position, there was a narrow luminous line, which could be rotated, by remote control, about the visual axis. At gravitoinertial force levels of 1.1-1.3G the subjects were asked to indicate, by repeatedly setting the line in darkness, what they perceived as horizontal (the SVH). During gondola centrifugation, the head and body length axis is always parallel with the resultant gravitoinertial force vector (vectorial sum of earth gravity force and the centrifugal force) i.e., the horizontal plane of the head or body does not change with respect to the gravitoinertial horizontal. Hence, the otolith organs, as well as the somatosensory system, continually signal upright position. However, the swing-out of the gondola during acceleration of the centrifuge (25 degrees at 1.1G) is a roll (frontal plane) change-in-position stimulus to the vertical semicircular canals, thus creating an otolith-semicircular canal conflict. After acceleration of the centrifuge, the SVH was initially tilted up to 20 degrees to the right relative to the gravitoinertial horizontal. Since there was no roll-tilt stimulus to gravity receptors, this SVH tilt must be related to stimulation of the semicircular canals. However, it decayed much more slowly than any known effects of angular-velocity stimulation of the semicircular canals. The decay was bi-phasic with two time constants, the smaller in the region of 1-2 min, the other being too large to be reliably estimated on the basis of data collected during only 10 min. This persistence of the SVH tilt suggests a memory for angular changes in roll head position detected by the semicircular canals-a position-storage mechanism. Further, the SVH seems to be dependent on two different mechanisms related to semicircular canal stimulation.
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| 2. |
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| 3. |
- Bagheri, Maryam, et al.
(författare)
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Genistein ameliorates learning and memory deficits in amyloid beta((1-40)) rat model of Alzheimers disease
- 2011
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier Science B.V., Amsterdam. - 1074-7427 .- 1095-9564. ; 95:3, s. 270-276
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimers disease (AD) is a debilitating neurodegenerative disorder characterized by increased beta-amyloid (A beta) deposition and neuronal dysfunction leading to impaired learning and recall. Ageing, heredity, and induced oxidative stress are among proposed risk factors. The increased frequency of the disease in women also suggests a role for estrogen in development of AD. In the present study, effects of the phytoestrogen genistein (10 mg/kg) on learning and memory impairments was assessed in intrahippocampal A beta((1-40))-injected rats. The estrogen receptor antagonist fulvestrant was injected intracerebroventricularly in a group of A beta-lesioned rats. The A beta-injected animals exhibited the following: lower spontaneous alternation score in Y-maze tasks, impaired retention and recall capability in the passive avoidance test, and fewer correct choices and more errors in the RAM task. Genistein, but not genistein and fulvestrant, significantly improved most of these parameters. Measurements of oxidative stress markers in hippocampal tissue of A beta-injected rats showed an elevation of malondialdehyde (MDA) and nitrite content, and a reduction of superoxide dismutase (SOD) activity. Genistein significantly attenuated the increased MDA content but did not affect the nitrite content or SOD activity. These results indicate that genistein pretreatment ameliorates A beta-induced impairment of short-term spatial memory in rats through an estrogenic pathway and by inducing attenuation of oxidative stress.
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| 4. |
- Brünner, Yvonne F., et al.
(författare)
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Neural correlates of olfactory and visual memory performance in 3D-simulated mazes after intranasal insulin application
- 2016
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 134:Part B, s. 256-263
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Tidskriftsartikel (refereegranskat)abstract
- This fMRI study intended to establish 3D-simulated mazes with olfactory and visual cues and examine the effect of intranasally applied insulin on memory performance in healthy subjects. The effect of insulin on hippocampus-dependent brain activation was explored using a double-blind and placebo-controlled design. Following intranasal administration of either insulin (40 ID) or placebo, 16 male subjects participated in two experimental MRI sessions with olfactory and visual mazes. Each maze included two separate runs. The first was an encoding maze during which subjects learned eight olfactory or eight visual cues at different target locations. The second was a recall maze during which subjects were asked to remember the target cues at spatial locations. For eleven included subjects in the fMRI analysis we were able to validate brain activation for odor perception and visuospatial tasks. However, we did not observe an enhancement of declarative memory performance in our behavioral data or hippocampal activity in response to insulin application in the fMRI analysis. It is therefore possible that intranasal insulin application is sensitive to the methodological variations e.g. timing of task execution and dose of application. Findings from this study suggest that our method of 3D-simulated mazes is feasible for studying neural correlates of olfactory and visual memory performance.
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| 5. |
- Bruno, Davide, et al.
(författare)
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The recency ratio is associated with reduced CSF glutamate in late-life depression.
- 2017
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Ingår i: Neurobiology of learning and memory. - : Elsevier BV. - 1095-9564 .- 1074-7427. ; 141, s. 14-18
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Tidskriftsartikel (refereegranskat)abstract
- Glutamate is the principal excitatory neurotransmitter in the central nervous system, and is thought to be involved in the process of memory encoding and storage. Glutamate disturbances have also been reported in psychiatric disorders, such as schizophrenia and major depressive disorder (MDD), and in Alzheimer's disease. In this paper, we set out to study the relationship between cerebrospinal fluid (CSF) glutamate levels and memory performance, which we believe has not been reported previously. In particular, we focused on recall performance broken down by serial position. Our prediction was that the recency ratio (Rr), a novel cognitive marker of intellectual impairment, would be linked with CSF glutamate levels. We studied data from a group of cognitively intact elderly individuals, 28 of whom had MDD, while 19 were controls. Study results indicated that Rr levels, but no other memory score, were inversely correlated with CSF glutamate levels, although this was found only in individuals with late-life MDD. For comparison, glutamine or GABA were not correlated with any memory performance measure.
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| 6. |
- Carvajal, Pedro, et al.
(författare)
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Central ghrelin increases anxiety in the Open Field test and impairs retention memory in a passive avoidance task in neonatal chicks
- 2009
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier. - 1074-7427 .- 1095-9564. ; 91:4, s. 402-407
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin (Grh) is an endogenous ligand for the growth hormone secretagogue receptor. Although Ghr stimulates feeding in rats, it inhibits feeding in neonatal chicks. However, little is known about other central behavioral effects of Ghr. Therefore, we investigated the Ghr effects, injected intracerebroventricularly, on anxiety and memory retention of neonatal chicks in an Open Field test and in a one-trial passive avoidance task, respectively. In the Open Field test, the administration of Ghr in a dose-dependent manner increased the latency to ambulate but decreased ambulation activity, indicating an anxiogenic effect. Furthermore, chicks trained on a passive avoidance task and injected with a dose of 30pmol of Ghr immediately after training showed an impairment of memory retention. However, there were no significant effects on the number of pecks during the pretraining, training, retention and discrimination. In addition, different doses of Ghr produced an inhibition in food intake at different times after injection. Our results indicate that Ghr induces anxiogenesis in chicks. Moreover, we have shown for the first time that Ghr can decrease memory retention in a non-mammalian species, suggesting that Ghr may play an important role in the processes of memory retention in birds.
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| 7. |
- Cedernaes, Jonathan, et al.
(författare)
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Learning and sleep-dependent consolidation of spatial and procedural memories are unaltered in young men under a fixed short sleep schedule
- 2016
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 131, s. 87-94
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate if a fixed short sleep schedule impairs one of the main functions of sleep, which is to consolidate newly learned memories. Methods: Sixteen young men participated in two experimental conditions, each of which lasted for 3 consecutive days and nights in our laboratory: a short sleep schedule (4.25-h sleep opportunity per night) versus a normal sleep schedule (8.5 h per night). In the evening after two experimental nights, participants learned locations of 15 card pairs (spatial memory task) and a procedural finger tapping sequence task. Post-sleep retrieval of both memory tasks was tested the next morning. Results: The short sleep schedule, compared with the normal sleep schedule, considerably altered sleep characteristics, e.g. the proportion of time in slow-wave sleep increased across the three experimental nights. In contrast, neither learning in the evening of day 2, nor subsequent overnight memory consolidation (i.e. concerning the change in memory performance between pre-sleep learning on day 2 and post sleep retrieval on day 3) differed between the normal and short sleep schedule conditions. Conclusions: Our findings suggest that learning in the evening and subsequent sleep-dependent consolidation of procedural and spatial memories are unaltered in young men living under a fixed short sleep schedule. Future studies are warranted to validate our findings in other groups (e.g. adolescents and older subjects) and after more prolonged chronic sleep loss paradigms.
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| 8. |
- Davidson, Per, et al.
(författare)
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A more generalized fear response after a daytime nap
- 2018
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier. - 1074-7427 .- 1095-9564. ; 151, s. 18-27
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine how a daytime nap affected the consolidation of fear learning. Participants first underwent fear conditioning during which they were exposed to a large and a small circle. One of these was repeatedly paired with an electric shock (making it the CS+), whereas the other circle was never paired with the shock (the CS-). After a delay interval containing either a nap or wake, participants again viewed the CS+ and the CS- intermixed with eight novel circles that varied in size between the two stimuli seen before, as well as a blue triangle that served as a novel stimulus without prior fear relevance. We examined both fear retention (the difference between the CS+ and the CS-) as well as fear generalization (responses to the novel stimuli based on their similarity to the original CS+). Contrary to previous studies, results from the participants who acquired a differentiated fear response during the acquisition phase revealed that the wake group showed significantly larger skin conductance responses to the CS+ compared to the CS-, whereas no such difference was present in the sleep group. These results were not driven by differences in explicit memory or by differences in general reactivity. Analyzing responses to the novel stimuli revealed a tendency towards a more generalized response in the sleep group, with no differences between the CS+ and any other stimulus, whereas the wake group showed increased responses to the stimuli depending on their similarity to the original CS+. This effect was however only present when controlling for baseline differences in worry.
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| 9. |
- Davidson, Per, et al.
(författare)
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A more generalized fear response after a daytime nap
- 2018
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 151, s. 18-27
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine how a daytime nap affected the consolidation of fear learning. Participants first underwent fear conditioning during which they were exposed to a large and a small circle. One of these was repeatedly paired with an electric shock (making it the CS+), whereas the other circle was never paired with the shock (the CS−). After a delay interval containing either a nap or wake, participants again viewed the CS+ and the CS− intermixed with eight novel circles that varied in size between the two stimuli seen before, as well as a blue triangle that served as a novel stimulus without prior fear relevance. We examined both fear retention (the difference between the CS+ and the CS−) and fear generalization (responses to the novel stimuli based on their similarity to the original CS+). Contrary to previous studies, results from the participants who acquired a differentiated fear response during the acquisition phase revealed that the wake group showed significantly larger skin conductance responses to the CS+ compared to the CS−, whereas no such difference was present in the sleep group. These results were not driven by differences in explicit memory or by differences in general reactivity. Analyzing responses to the novel stimuli revealed a tendency towards a more generalized response in the sleep group, with no differences between the CS+ and any other stimulus, whereas the wake group showed increased responses to the stimuli depending on their similarity to the original CS+. This effect was however only present when controlling for baseline differences in worry.
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| 10. |
- Dohm-Hansen, Sebastian, et al.
(författare)
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Mnemonic discrimination of object and context is differentially associated with mental health
- 2020
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427. ; 173
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Tidskriftsartikel (refereegranskat)abstract
- Episodic memories are formed by hippocampal binding of the "what" and "where" features of everyday events. The hippocampus minimizes interference between related similar episodic memories by pattern separation. Stress and psychopathology are associated with lowered pattern separation. While current behavioral paradigms typically use correct rejections of single object or context lures rather than composite stimuli, it is not known if object and context pattern separation differentially associate with mental health. We reasoned that an object-in-context paradigm would be more sensitive to mental health state than current implementations, given increased task demands. We found that non-clinical depression and anxiety symptom severity were associated with reduced lure rejection for both object and context, and that only the object domain was associated with a concomitant increase in lure overgeneralization. Therefore, we argue that reduced lure rejection and increased overgeneralization must not be conflated. Although our object-in-context paradigm was not more sensitive to variation in mental health, we show that lure rejection and overgeneralization rate in one domain (e.g. object) was affected by the status of the other domain (e.g. context target versus lure). Finally, as several metrics of pattern separation exist in the literature, we evaluated the association of different metrics with mental health.
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| 11. |
- Dunsmoor, Joseph E., et al.
(författare)
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Extinction in multiple virtual reality contexts diminishes fear reinstatement in humans
- 2014
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 113:0, s. 157-164
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Although conditioned fear can be effectively extinguished by unreinforced exposure to a threat cue, fear responses tend to return when the cue is encountered some time after extinction (spontaneous recovery), in a novel environment (renewal), or following presentation of an aversive stimulus (reinstatement). As extinction represents a context-dependent form of new learning, one possible strategy to circumvent the return of fear is to conduct extinction across several environments. Here, we tested the effectiveness of multiple context extinction in a two-day fear conditioning experiment using 3-D virtual reality technology to create immersive, ecologically-valid context changes. Fear-potentiated startle served as the dependent measure. All three experimental groups initially acquired fear in a single context. A multiple extinction group then underwent extinction in three contexts, while a second group underwent extinction in the acquisition context and a third group underwent extinction in a single different context. All groups returned 24 h later to test for return of fear in the extinction context (spontaneous recovery) and a novel context (renewal and reinstatement/test). Extinction in multiple contexts attenuated reinstatement of fear but did not reduce spontaneous recovery. Results from fear renewal were tendential. Our findings suggest that multi-context extinction can reduce fear relapse following an aversive event – an event that often induces return of fear in real-world settings – and provides empirical support for conducting exposure-based clinical treatments across a variety of environments.
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| 12. |
- Ghirlanda, Stefano, 1972-, et al.
(författare)
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How associations become behavior
- 2023
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Ingår i: Neurobiology of Learning and Memory. - 1074-7427 .- 1095-9564. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- The Rescorla and Wagner (1972) model is the first mathematical theory to explain associative learning in the presence of multiple stimuli. Its main theoretical construct is that of associative strength, but this is connected to behavior only loosely. We propose a model in which behavior is described by a collection of Poisson processes, each with a rate proportional to an associative strength. The model predicts that the time between behaviors follows an exponential or hypoexponential distribution. This prediction is supported by two data sets on autoshaped and instrumental behavior in rats.
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| 13. |
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| 14. |
- Johansson, Fredrik
(författare)
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Intrinsic memory of temporal intervals in cerebellar Purkinje cells
- 2019
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427. ; 166
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Tidskriftsartikel (refereegranskat)abstract
- The general consensus for learning and memory, including in the cerebellum, is that modification of synaptic strength via long-term potentiation (LTP) or long-term depression (LTD) are the primary mechanisms for the formation of memories. Recent findings suggest additional cellular mechanisms – referred to as ‘intrinsic plasticity’ – where a neuron's membrane excitability intrinsically changes. These mechanisms act like a dimmer and alter neuronal responsiveness by adjusting response amplitudes and spike thresholds. Here, I argue that classical conditioning of cerebellar Purkinje cell responses reveals yet another cell-intrinsic learning mechanism which significantly differs from both changes in synaptic strength and changes in membrane excitability. When the conditional (CS) and unconditional stimuli (US) are delivered directly to the Purkinje cell's immediate pre-synaptic afferents, the parallel fibres and the climbing fibre, the cell learns to respond to the CS with a pause in its spontaneous firing that reflects the interval between the two stimuli. The pause response has a delayed onset and adaptively timed maximum, offset and duration, determined by the previously experienced CS-US interval. The timing is not dependent on any network-generated time-varying input. This implies the existence of a timing mechanism and a memory substrate that encodes the duration of the CS-US interval inside the Purkinje cell. Such temporal interval learning is not simply a change that causes more or less firing in response to an input. Here, I review these findings in relation to the standard theory of synaptic strength changes and the network interactions believed to be necessary for generating time codes.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
- Persson, Ninni, et al.
(författare)
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Synergy effects of HbA(1c) and variants of APOE and BDNFVal(66)Met explains individual differences in memory performance
- 2013
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 106, s. 274-282
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Tidskriftsartikel (refereegranskat)abstract
- We aimed at exploring if synergy effects of Brain-Derived Neurotrophic Factor (BDNF) Val66Met, Apolipoprotein E (APOE) and HbA1c (glycated haemoglobin) could explain individual differences in memory performance over 10 years in a population based sample of nondemented adults (N = 888, 35–85 years at baseline). Episodic memory was affected by such agents, wheras semantic memory was spared. Both age and HbA1c were associated with episodic memory decline. BDNF66Met carriers with higher HbA1c levels evidenced slope decline in episodic recall. We found support for joint effects ofBDNFVal66Met × APOE × HbA1c and BDNFVal66Met × APOE × age on rates of episodic memory change over ten years, after controlling for age, sex, education and cardiovascular diseases. We conclude that variants of genetic polymorphisms act in synergy with long-term blood glucose control in shaping patterns of cognitive aging.
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| 19. |
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| 20. |
- Pickering, Chris, et al.
(författare)
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To press or not to press? Differential receptor expression and response to novelty in rats learning an operant response for reward
- 2007
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 87:2, s. 181-191
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Tidskriftsartikel (refereegranskat)abstract
- Learning to perform instrumental tasks is an ability of all animals. In a population of rats, not all individuals will acquire an operant response for reward. We hypothesized that there could be a genetic explanation for differences between High Consumers (those that acquired the lever press response) and Low Consumers (lever press response is low). Additionally, we proposed that this genetic difference could produce measurable changes in response to novelty. Wistar rats were trained to lever press for a 0.2% saccharin reward and on the 10th day they were placed in a novel open field for 30 min to record locomotor activity. The prefrontal cortex and hippocampus were dissected and qPCR was used to measure mRNA expression. A significant difference (p=.048; 2-way ANOVA) in gene expression was observed between Low and High Consumers. A principal component analysis (PCA), to cluster which genes represent this difference, identified 4 genes; 5-HT2A and mGlu1 in the hippocampus and AMPA GluR1 and adrenergic alpha2A in the prefrontal cortex. Response to a novel open field also differed since Low Consumers displayed a higher Total Distance in comparison to High Consumers. Additionally, Low Consumers could be subdivided into Low-Lever (with lever press response only when water deprived) and Low-Non-Lever (lever press response is low throughout training). PCA with this subdivision identified an additional nine genes differing within the divisions; NMDA NR2B and GABAAalpha3 in the prefrontal cortex and adrenergic alpha2B and alpha2A, AMPA GluR1, GluR2 and GluR3, 5-HT1B and GABAAalpha5 in the hippocampus.
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| 21. |
- Purple, R. J., et al.
(författare)
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Sleep-related memory consolidation in the psychosis spectrum phenotype
- 2020
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier. - 1074-7427 .- 1095-9564. ; 174
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Tidskriftsartikel (refereegranskat)abstract
- Sleep and memory processing impairments range from mild to severe in the psychosis spectrum. Relationships between memory processing and sleep characteristics have been described for schizophrenia, including unaffected first-degree relatives, but they are less clear across other high-risk groups within the psychosis spectrum. In this study, we investigated high-risk individuals with accumulated risk-factors for psychosis and subthreshold symptoms. Out of 1898 screened individuals, 44 age- and sex-matched participants were sub-grouped into those with substantial environmental risk factors for psychosis and subthreshold psychotic symptoms (high-risk group) and those without these phenotypes (low-risk controls). Four groups (high/low risk, morning/evening training) were trained and tested in the laboratory for sustained attention, motor skill memory (finger-tapping task) and declarative memory (word-pair learning task) immediately after training, again after a night of EEG-recorded sleep at home or a period of daytime wakefulness, and again after 24 h from training. No differences in sustained attention or in memory consolidation of declarative and motor skill memory were found between groups for any time period tested. However, a group difference was found for rapid-eye movement (REM) sleep in relation to motor skill memory: the longer the total sleep time, particularly longer REM sleep, the greater the performance gain, which occurred only in high-risk individuals. In conclusion, our results suggest a gain in motor skill performance with sufficient sleep opportunity for longer REM sleep in high-risk individuals with subthreshold psychotic symptoms. Declarative memory did not benefit from sleep consolidation above or beyond that of the control group.
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| 22. |
- Rasmussen, Anders
(författare)
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Graded error signals in eyeblink conditioning
- 2020
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427. ; 170
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Forskningsöversikt (refereegranskat)abstract
- Minimizing errors is an important aspect of learning. However, it is not enough merely to record if an error occurred. For efficient learning, information about the magnitude of errors is critical. Did my tennis swing completely miss the target or did I hit the ball, but not quite in the sweet spot? How can neurons – which have traditionally been thought of as binary units – signal the magnitude of an error? Here I review evidence that eyeblink conditioning – a basic form of motor learning – depends on graded signals from the inferior olive which guides plasticity in the cerebellum and ultimately tunes behavior. Specifically, evidence suggests that: (1)Error signals are conveyed to the cerebellum via the inferior olive; (2)Signals from the inferior olive are graded; (3)The strength of the olivary signal affects learning; (4)Cerebellar feedback influences the strength of the olivary signal. I end the review by exploring how graded error signals might explain some behavioral learning phenomena.
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| 23. |
- Rosén, Jörgen, et al.
(författare)
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Social, proximal and conditioned threat
- 2017
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Ingår i: Neurobiology of Learning and Memory. - : Elsevier BV. - 1074-7427 .- 1095-9564. ; 142, part B, s. 236-243
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Tidskriftsartikel (refereegranskat)abstract
- Responding to threats in the environment is crucial for survival. Certain types of threat produce defensive responses without necessitating previous experience and are considered innate, whereas other threats are learned by experiencing aversive consequences. Two important innate threats are whether an encountered stimulus is a member of the same species (social threat) and whether a stimulus suddenly appears proximal to the body (proximal threat). These threats are manifested early in human development and robustly elicit defensive responses. Learned threat, on the other hand, enables adaptation to threats in the environment throughout the life span. A well-studied form of learned threat is fear conditioning, during which a neutral stimulus acquires the ability to eliciting defensive responses through pairings with an aversive stimulus. If innate threats can facilitate fear conditioning, and whether different types of innate threats can enhance each other, is largely unknown. We developed an immersive virtual reality paradigm to test how innate social and proximal threats are related to each other and how they influence conditioned fear. Skin conductance responses were used to index the autonomic component of the defensive response. We found that social threat modulates proximal threat, but that neither proximal nor social threat modulates conditioned fear. Our results suggest that distinct processes regulate autonomic activity in response to proximal and social threat on the one hand, and conditioned fear on the other.
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| 24. |
- Shionoya, Kiseko, 1964-, et al.
(författare)
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Inactivation of the basolateral amygdala impairs the retrieval of recent and remote taste-potentiated odor aversion memory
- 2009
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Ingår i: Neurobiology of Learning and Memory. - : Academic Press. - 1074-7427 .- 1095-9564. ; 92:4, s. 590-596
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Tidskriftsartikel (refereegranskat)abstract
- Memory reorganization as a time-dependent process can be investigated using various learning tasks such as the taste-potentiated odor aversion (TPOA). In this paradigm rats acquire a strong aversion to an olfactory cue presented simultaneously with a gustatory cue. Together these cues are paired with a delayed visceral illness. The basolateral amygdaloid nucleus (BLA) plays a key role in TPOA acquisition but its involvement in retrieval remains unclear. We investigated the involvement of the BLA in either recent or remote retrieval of TPOA. In each case, the number of licks observed in response to the presentation of either the odor or the taste was used to assess retrieval. Before the retrieval test, rats received a bilateral infusion of lidocaine to inactivate the BLA. We observed that both recent and remote TPOA retrieval tests induced by the odor presentation were disrupted in the lidocaine-injected rats. By contrast, the BLA inactivation had no effect upon the aversion towards the taste cue regardless of the time of retrieval. The present study provides evidence that BLA functioning is necessary for retrieval of aversive odor memory, even with a long post-acquisition delay.
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