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Neurobiology of Learning and Memory

T Lee Gilman, Sohini Dutta, Jordan M Adkins, Cassandra A Cecil, Aaron M Jasnow
Disrupted fear inhibition is a characteristic of many anxiety disorders. Investigations into the neural mechanisms responsible for inhibiting fear will improve understanding of the essential circuits involved, and facilitate development of treatments that promote their activity. Within the basolateral amygdala (BLA), Thy1-expressing neuron activity has been characterized by us and others as promoting fear inhibition to discrete fear cues by influencing consolidation of cued fear learning or cued fear extinction...
October 1, 2018: Neurobiology of Learning and Memory
Denis Drapeau
In animal behavioral experiments, extended training causes instrumental actions that deliver ingestible substances to lose sensitivity to outcome devaluation and contingency degradation, and to gain direct sensitivity to the current motivational state. These features of habitual control have been attributed to a process that relies on stimulus-response (S-R) associations linking the context to instrumental actions and Pavlovian associations linking the same context to orally-sensed properties of substances attained there...
September 27, 2018: Neurobiology of Learning and Memory
Da Song, Qinghu Yang, Yiran Lang, Zhaosen Wen, Zhen Xie, Da Zheng, Tianyi Yan, Yujun Deng, Hiroshi Nakanishi, Zhenzhen Quan, Hong Qing
The CA3 subregion of the hippocampus is important for rapid encoding, storage and retrieval of associative memories. Lesions and pharmacological inhibitions of hippocampal CA3 suggest that it is essential for different memories. However, how CA3 functions in spatial and episodic memory in different time scales (i.e. short-term versus long term) without permanent lesions has not been systematically investigated yet. Taking advantage of the chemogenetic access to opsins, this study used luminopsins, fusion proteins of luciferase and optogenetic elements, to manipulate neuronal activity in CA3 during memory tasks over a range of spatial and temporal scales...
September 19, 2018: Neurobiology of Learning and Memory
Ushma Patel, Leticia Perez, Steven Farrell, Derek Steck, Athira Jacob, Tania Rosiles, Everett Krause, Melissa Nguyen, Robert J Calin-Jageman, Irina E Calin-Jageman
Most long-term memories are forgotten, becoming progressively less likely to be recalled. Still, some memory fragments may persist, as savings memory (easier relearning) can be detected long after recall has become impossible. What happens to a memory trace during forgetting that makes it inaccessible for recall and yet still effective to spark easier re-learning? We are addressing this question by tracking the transcriptional changes that accompany learning and then forgetting of a long-term sensitization memory in the tail-elicited siphon withdrawal reflex of Aplysia californica...
September 19, 2018: Neurobiology of Learning and Memory
Laura A Bradfield, Genevra Hart, Bernard W Balleine
Although studies examining orbitofrontal cortex (OFC) often treat it as though it were functionally homogeneous, recent evidence has questioned this assumption. Not only are the various subregions of OFC (lateral, ventral, and medial) hetereogeneous, but there is further evidence of heterogeneity within those subregions. For example, several studies in both humans and monkeys have revealed a functional subdivision along the anterior-posterior gradient of the medial OFC (mOFC). Given our previous findings suggesting that, in rats, the mOFC is responsible for inferring the likelihood of unobservable action outcomes (Bradfield, Dezfouli, van Holstein, Chieng, & Balleine, 2015), and given the anterior nature of the placements of our prior manipulations, we decided to assess whether the rat mOFC also differs in connection and function along its anteroposterior axis...
September 19, 2018: Neurobiology of Learning and Memory
Zhixiong He, Qianqian Guo, Yang Yang, Limin Wang, Siyi Zhang, Wei Yuan, Laifu Li, Jing Zhang, Wenjuan Hou, Jinfeng Yang, Rui Jia, Fadao Tai
Disruption of the early social environment, such as maternal separation or early deprivation, can impair cognitive function, alter offspring neurogenesis and restrict dendritic architecture in the hippocampus. However, whether paternal deprivation during the pre-weaning period affects adult neurogenesis, synaptogenesis and social recognition remains unclear in monogamous species. In the present study, mandarin vole (Microtus mandarinus) pups were deprived of fathers during postnatal day 14-21. Then social recognition, hippocampal neurogenesis and spine density, basal levels of corticosterone (CORT) and oxytocin (OT) were examined at adulthood...
September 19, 2018: Neurobiology of Learning and Memory
Alex Hanson, Brian D Burrell
Repetitive activation of non-nociceptive afferents is known to attenuate nociceptive signaling. However, the functional details of how this modulatory process operates are not understood and this has been a barrier in using such stimuli to effectively treat chronic pain. The present study tests the hypothesis that the ability of repeated non-nociceptive stimuli to reduce nociception is a form of generalized habituation from the non-nociceptive stimulus-response pathway to the nociceptive pathway. Habituation training, using non-nociceptive mechanosensory stimuli, did reduce responses to nociceptive thermal stimulation...
September 6, 2018: Neurobiology of Learning and Memory
Meghraj Singh Baghel, Brijendra Singh, Yogesh Kumar Dhuriya, Rajendra Kumar Shukla, Nisha Patro, Vinay Kumar Khanna, Ishan Kumar Patro, Mahendra Kumar Thakur
Viral infection during early stage of life influences brain development and results in several neurodevelopmental disorders such as schizophrenia, autism and behavioral abnormalities. However, the mechanism through which infection causes long-term behavioral defects is not well known. To elucidate this, we have used synthetic polyinosinic-polycytidylic acid [poly (I:C)] which acts as a dsRNA molecule and interacts with toll-like receptor-3 (TLR-3) of microglia cells to evoke the immune system, thus mimicking the viral infection...
September 6, 2018: Neurobiology of Learning and Memory
Crhistian Luis Bender, Marcelo Giachero, Ramiro Comas-Mutis, Victor Alejandro Molina, Gastón Diego Calfa
Fear extinction is defined as a decline in fear-conditioned responses following non-reinforced exposure to a fear conditioned stimulus, therefore the conditioned stimulus gains new predictive properties. Patients with anxiety related disorders (e.g.: PTSD) subjected to extinction-like exposure treatments often experience a relapse of symptoms. Stress is a risk factor for those psychiatric disorders and a critical modulator of fear learning that turns the memory resistant to the extinction process. Dendritic spines are the anatomical sites where neuronal activity reshapes brain networks during learning and memory processes...
September 6, 2018: Neurobiology of Learning and Memory
Saida Haider, Saiqa Tabassum
Among multiple behavioral tasks used to assess memory performance, Morris water maze (MWM) is a well-known and reliable conventional behavioral task to monitor spatial memory performance in rodents. Although multiple procedures are employed by researchers for spatial learning training in MWM, but less is known about impact of these training protocol variations on oxidative and neurochemical systems. Therefore, this study aimed to examine whether variations in training protocol will influence spatial memory performance and induce changes in oxidative status and cholinergic and aminergic neurotransmission in rat brain...
September 5, 2018: Neurobiology of Learning and Memory
Bronwyn M Graham, Vanessa Dong, Rick Richardson
Phenotypic differences in conditioned fear expression may be a marker of vulnerability to the development of anxiety disorders. Hippocampal FGF2 correlates negatively with conditioned fear expression, and antidepressants, the first-line pharmacological treatment for anxiety, increase hippocampal FGF2. In the present study, we assessed whether treatment with the selective serotonin reuptake inhibitor fluoxetine reduces conditioned fear expression in rats that naturally express lower (Low fear) or higher (High fear) levels of fear following a single-trial conditioning session...
September 5, 2018: Neurobiology of Learning and Memory
Dennis M Maharjan, Yu Y Dai, Ethan H Glantz, Shantanu P Jadhav
The hippocampus (HPC) and prefrontal cortex (PFC) are both necessary for learning and memory-guided behavior. Multiple direct and indirect anatomical projections connect the two regions, and HPC - PFC functional interactions are mediated by diverse physiological network patterns, thought to sub serve various memory processes. Disconnection experiments using contralateral inactivation approaches have established the role of direct, ipsilateral projections from ventral and intermediate HPC (vHPC and iHPC) to PFC in spatial memory...
September 1, 2018: Neurobiology of Learning and Memory
Rajat Thapa, Aaron J Gruber
Animals tend to repeat actions that are associated with reward delivery, whereas they tend to shift responses to alternate choices following reward omission. These so-called win-stay and lose-shift responses are employed by a wide range of animals in a variety of decision-making scenarios, and depend on dissociated regions of the striatum. Specifically, lose-shift responding is impaired by extensive excitotoxic lesions of the lateral striatum. Here we used focal lesions to assess whether dorsal and ventral regions of the lateral striatum contribute differently to this effect...
September 1, 2018: Neurobiology of Learning and Memory
Rodrigo S Maeda, Steven E McGee, Daniel S Marigold
Visuomotor adaptation is a form of motor learning that enables accurate limb movements in the presence of altered environmental or internal conditions. It requires updating the mapping between visual input and motor output, and can occur when learning a new device/tool or during rehabilitation after neurological injury. In either case, it is desirable to stabilize, or consolidate, this visuomotor memory for long-term usage. However, reactivation of a consolidated memory, whether it is motor-based or not, is thought to render it temporarily fragile again, and thus susceptible to interference or modification...
August 31, 2018: Neurobiology of Learning and Memory
Martin I Antov, Ursula Stockhorst
Stress is a potent modulator of learning and memory. Factors contributing to whether stress aids or impairs memory are timing of the stressor, memory stage, form of memory studied, and sex of the subjects. The female sex hormone 17-beta-estradiol (E2) has widespread effects in the brain and affects hippocampus-dependent memory in animals. In humans, the interaction between stress effects and E2 has not been widely studied. We report data from a healthy sample divided into 3 hormone-status groups: free-cycling women in the early follicular phase (EF: low E2, low progesterone [P4]), or during midcycle (MC: high E2, low P4), and men...
August 30, 2018: Neurobiology of Learning and Memory
Jian-You Lin, Joe Arthurs, Steve Reilly
The current study examined the effects of transient inactivation of the basolateral amygdala (BLA; Experiment 1) and gustatory cortex (GC; Experiment 2) on the expression of taste neophobia and its recovery. We found that inactivation (induced by infusions of baclofen/muscimol) of each structure before exposure to a novel saccharin (0.5%) solution elevated intake on Trial 1 (i.e., taste neophobia was attenuated) and, surprisingly, decreased intake on Trial 2. It seems unlikely that this intake reduction on Trial 2 can be attributed to taste aversion learning caused by drug infusions because in the subsequent experiments with the same set of the implanted animals, the rats did not decrease intake when baclofen/muscimol was infused after taste presentation on Trial 1...
August 30, 2018: Neurobiology of Learning and Memory
Magdalena Miranda, Brianne A Kent, Juan Facundo Morici, Francisco Gallo, Lisa M Saksida, Timothy J Bussey, Noelia Weisstaub, Pedro Bekinschtein
Successful memory involves not only remembering information over time but also keeping memories distinct and less confusable. Discrimination of overlapping representations has been investigated in the dentate gyrus (DG) of the hippocampus and largely in the perirhinal cortex (Prh). In particular, the DG was shown to be important for discrimination of overlapping spatial memories and Prh was shown to be important for discrimination of overlapping object memories. In the present study, we used both a DG-dependent and a Prh-dependent task and manipulated the load of similarity between either spatial or object stimuli during information encoding...
August 30, 2018: Neurobiology of Learning and Memory
R L Sumner, M J Spriggs, R L McMillan, F Sundram, I J Kirk, S D Muthukumaraswamy
In healthy women, fluctuations in hormones including progesterone and oestradiol lead to functional changes in the brain over the course of each menstrual cycle. Though considerable attention has been directed towards understanding changes in human cognition over the menstrual cycle, changes in underlying processes such as neural plasticity have largely only been studied in animals. In this study we explored predictive coding and repetition suppression via the roving mismatch negativity paradigm as a model of short-term plasticity (Garrido, Kilner, Kiebel, et al...
August 30, 2018: Neurobiology of Learning and Memory
Matthew A Tucker, Kathryn Taylor, Rozina Merchant, Sharon George, Caroline Stoddard, Kevin Kopera
It has been proposed that normal waking levels of acetylcholine (ACH) are important for initial memory acquisition, and that decreased ACH is critical for memory consolidation. Sleep is thought to benefit memory consolidation in part due to the predominance of low ACH levels observed during non-rapid eye movement sleep. Here we examined whether sleep and ACH suppression with the cholinergic antagonist scopolamine impact declarative and motor memory consolidation across a night of sleep or a day of wakefulness...
August 30, 2018: Neurobiology of Learning and Memory
Meera E Modi, Mustafa Sahin
Recent advances in circuit manipulation technologies have enabled the association of distinct neural circuits with complex social behaviors. The brain areas identified through historical anatomical characterizations as mediators of sexual and parental behaviors can now be functionally linked to adult social behaviors within a unified circuit. In vivo electrophysiology, optogenetics and chemogenetics have been used to follow the processing of social sensory stimuli from perception by the olfactory system to valence detection by the amygdala and mesolimbic dopamine system to integration by the cerebral and cerebellar cortices under modulation of hypothalamic neuropeptides...
August 24, 2018: Neurobiology of Learning and Memory
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