Illustration-Brain Regions
There are many brain regions that are involved in memory recognition and retrieval. The sensory cortex is located in the rear of the brain in the posterior cortex. The prefrontal regions or anterior cortex are in the front. Lateral prefrontal regions (lPFC), those structures that run along the perimeter of the prefrontal cortex, are involved in anticipation, preparatory cognition, response inhibition, and cognitive processing. The anterior prefrontal cortex or frontal pole is specialized for long term memory retrieval. The areas of the cortex that are closest to the front (anterior) top (dorsal) surface but deep in the middle or medial of the brain are called dorsal medial prefrontal structures (mPFC). More anterior areas toward the bottom (ventral) of the mPFC are involved in stress inhibition and retrieving long term memory. More posterior regions of the medial surface are involved in sensory, intermediate memory processing, and recallable recognition. The cingulate cortex takes up most of the cortical medial surface. It has a posterior region, posterior cingulate cortex (PCC), middle region, midcingulate cortex (MCC), and anterior region, perigenual anterior cingulate cortex (pACC) which is divided into dorsal and ventral areas. The pACC is also part of the mPFC, whose regional delineations are wider than pACC. All cortical areas are independently involved in short-term memory processing and need an intact medial temporal lobe (MTL) to make memories long term and permanent. The next area is the MTL consisting of the hippocampus (HPC) and amygdala (AMY). The hippocampus is specialized for relational processing and the retrievability of long term memory. Its surrounding structures, e.g. the perirhinal (PRC), parahippocampal (PHC) and entorhinal (EC) cortices, are part of the hippocampal system or hippocampal formation. They are also referred to, in total, as being extra-hippocampal, hippocampal surrounding areas, or extra MTL region. They facilitate intermediate and long term memory processing by carrying neural information to the hippocampus. The AMY mediates the emotion of fear and attachment behaviors with its connections with deeper structures like the striatum. The striatal’s dorsal region is specialized for automatic motor behaviors and ventral region, for motivation. The thalamus is a major relay structure that in direct or indirect ways projects to most of the cortex. These regions are all reflected in Figure 2. Figure 2 is a medial view of the brain superimposed on a lateral view to allow for enhanced regional identification. Brain regions noted in the text are reflected on this diagram along with functions subsequently noted and cited in the text.