View clinical trials related to Consolidation.
Filter by:Acting adaptively requires quickly picking up on structure in the environment and storing the acquired knowledge for effective future use. Dominant theories of the hippocampus have focused on its ability to encode individual snapshots of experience, but the investigators and others have found evidence that it is also crucial for finding structure across experiences. The mechanisms of this essential form of learning have not been established. The investigators have developed a neural network model of the hippocampus instantiating the theory that one of its subfields can quickly encode structure using distributed representations, a powerful form of representation in which populations of neurons become responsive to multiple related features of the environment. The first aim of this project is to test predictions of this model using high resolution functional magnetic resonance imaging (fMRI) in paradigms requiring integration of information across experiences. The results will clarify fundamental mechanisms of how humans learn novel structure, adjudicating between existing models of this process, and informing further model development. There are also competing theories as to the eventual fate of new hippocampal representations. One view posits that during sleep, the hippocampus replays recent information to build longer-term distributed representations in neocortex. Another view claims that memories are directly and independently formed and consolidated within the hippocampus and neocortex. The second aim of this project is to test between these theories. The investigators will assess changes in hippocampal and cortical representations over time by re-scanning participants and tracking changes in memory at a one-week delay. Any observed changes in the brain and behavior across time, however, may be due to generic effects of time or to active processing during sleep. The third aim is thus to assess the specific causal contributions of sleep to the consolidation of structured information. The investigators will use real-time sleep electroencephalography to play sound cues to bias memory reactivation. The investigators expect that this work will clarify the anatomical substrates and, critically, the nature of the representations that support encoding and consolidation of novel structure in the environment.
Background: Neoadjuvant chemoradiation (nCRT) has been considered the preferred initial treatment strategy for distal rectal cancer. Advantages of this approach include improved local control after radical surgery but also the opportunity for organ preserving strategies (Watch and Wait - WW). Consolidation chemotherapy (cCT) regimens using fluoropyrimidine-based with or without oxaliplatin following nCRT have demonstrated to increase complete response and organ preservation rates among these patients. However, the benefit of adding oxaliplatin to cCt compared to fluoropyrimidine alone regimens in terms of primary tumor response remains unclear. Since oxaliplatin-treatment may be associated with considerable toxicity, it becomes imperative to understand the benefit of its incorporation into standard cCT regimens in terms of primary tumor response. The aim of the present trial is to compare the outcomes of 2 different cCT regimens following nCRT (fluoropyrimidine-alone versus fluoropyrimidine+oxaliplatin) for patients with distal rectal cancer. Methods: In this multi-centre study, patients with magnetic resonance-defined distal rectal tumors will be randomized on a 1:1 ratio to receive long-course chemoradiation (54Gy) followed by cCT with fluoropyrimidine alone versus fluoropyrimidine+oxaliplatin. Magnetic resonance (MR) will be analyzed centrally prior to patient inclusion and randomization. mrT2-3N0-1 tumor located no more than 1cm above the anorectal ring determined by sagittal views on MR will be eligible for the study. Tumor response will be assessed after 12 weeks from radiotherapy (RT) completion. Patients with clinical complete response (clinical, endoscopic and radiological) will be enrolled in an organ-preservation program (WW). The primary endpoint of this trial is decision to organ-preservation surveillance (WW) at 18 weeks from RT completion. Discussion: Long-course nCRT with cCT is associated with improved complete response rates and may be a very attractive alternative to increase the chances for organ-preservation strategies. Fluoropyrimidine-based cCT with or without oxaliplatin has never been investigated in the setting of a randomized trial to compare clinical response rates and the possibility of organ-preservation. The outcomes of this study may significantly impact clinical practice of patients with distal rectal cancer interested in organ-preservation.
The proposed studies focus on memory for speech movements and sounds and its relation to learning. Continuous theta-burst transcranial magnetic stimulation (cTBS) will be used to suppress activity in a region of pre-frontal cortex associated with somatic and auditory working memory (Brodmann area 46v) to test its involvement in learning.
These studies test the hypothesis that the repeated pairing of somatosensory inputs with speech sounds, such as occurs during speech motor learning, results in changes to the perceptual classification of speech sounds.
Forgetting is often perceived as the inability to retain information, but in fact at least some memory deterioration is due to active suppression processes, that are behaviorally adaptive. These active processes are thought to involve new, inhibitory learning, suggesting that sleep may serve to enhance them as it does other forms of learning. If this were the case, sleep may be harnessed to weaken non-adaptive memories in a manner that may be beneficial for healthy and clinical populations suffering from memory-related symptoms of disorders such as post-traumatic stress disorder (PTSD). To test this idea, this suggested nap study will incorporate specific memories in a suppression context during sleep monitored by encephalography (EEG). First, participants will take part in an item-based directed forgetting task, in which they will be exposed to different words, immediately followed by instructions to either remember the preceding word or not. The instructions will be conveyed using two distinct odors. In fact, the purpose of this first part would be to cement the associations of these odors with the instructions. Next, in an unrelated task, participants will learn the spatial locations of images on a screen. These images will be presented along with congruent sounds (e.g., cat - meow). During a subsequent nap, some of these sounds will be unobtrusively presented along with one of the two previously learned odors or along with a novel odor. In a final spatial-location test, memory for the images whose sounds were presented along with the "forget" odor during sleep is expected to be worse than for the images that were not cued. Memory for the locations of the images whose sounds were presented with one of the two other odors during sleep are expected to improve, possibly more so for the sounds presented with the "remember" odor relative to those presented with the novel odor. If successful, these results would be a first step towards interventions that may serve to selectively weaken memory during sleep.
These studies test the hypothesis that sensory areas of the brain participate in the consolidation of speech motor memory by using transcranial magnetic stimulation to suppress activity in somatosensory and auditory cortex following adaptation in order to block retention of learning.