Declarative Memory

Memory can be declarative or procedural. A declarative memory would be concerned with the experiences and facts, while a procedural memory is related to skills. A declarative memory is further classified into episodic memory and semantic memory. An episodic memory is based on awareness of a previous experience in a particular situation at a particular time. It develops throughout childhood. A semantic memory is concerned with the factual knowledge about the world (Tulving 1983,1993,2002). The article initially explains the cognitive neuroscience of the development of the episodic memory formation. Behavioral evidence indicates an episodic memory emerges from childhood through adulthood. Developments in cognitive functions such as speed of

The DMN may be activated in internal- and self-oriented processing. Repression of the DMN, suggests fortunate operation of cognitive processes that requires attention to the environment. A task induced deactivation of the DMN might indicate repression of attention to one's own thought and feelings and encourage the allocation of mental and neural resources to tasks involving external stimuli. With episodic memory development, deactivation of DMN could be experiences that would magnify the resources to memory encoding of external stimuli. The study encompasses 52 volunteers ages 8 to 24 years. All the subjects were right-handed, and had normal or corrected-to-normal vision, with no history of psychiatric or neurological disorder. A total of 4 subjects was excluded, two on the basis of incomplete data while, another two on the basis of the motion. The next step was memory task, wherein participants were asked to observe 125 indoor and 125 outdoor scenes, that was followed by a recognition memory test. Further, following the scan, the participants were provided 250 new scenes. Furthermore, if the subjects selected old to a scene, they were questioned to specify if they actually remembered (R) or if the scene just looks familiar (F).

Additionally, in adults the greater degree of anti-correlation between DMN and task-positive networks exhibit better cognitive control and working memory task performance. Research hypothesizes, an anti-correlation between DMN and task-positive network strengthens during development. Moreover, anti-correlation increases with age. To prove the hypotheses, 82 participants with ages of 8-24 years were included. All the subjects were right-handed, and had normal or corrected-to-normal vision, with no history of psychiatric or neurological disorder. A fMRI scan was acquired and processed using SPM8. Further, functional connectivity was initiated using seed based connectivity technique in fConn toolbox. A CompCor method was utilized for noise reduction. A partial volume effect in gray matter (GM), the white matter (WM) and CSF masks was minimized by eroding one voxel. Later, the eroded WM and CSF masks were employed as noise region-of interests (ROIs). A first level connectivity map was produced from each seed for each participant, which helped in evaluating age-related changes in connectivity. The connectivity map was a group level whole-brain regression analysis with age as a covariate. Furthermore, a two-sample t-test was performed to compare the connectivity maps between children and adults for movement and artifact. Analysis showed developmental changes in the DMN of all the four seeds in a whole brain correlation