Is the Hippocampus responsible for Declarative Conscious Memory ?

Researchers have generally agreed the hippocampus is essential in developing memory. The skull envelopes the brain all of which has four lobes: frontal, occipital, partial, and temporal. Each lobe serves a function; Lobe 1-frontal: rationale and personality; Lobe 2-occipital: visual perception; Lobe 3-parietal: sensory perception and integration of the visual and sensory systems; and Lobe 4-temporal: hearing, memory acquisition, some visual perception, and categorization of objects. The hippocampus is part of the medial temporal lobe (MTL) or hippocampal system. The role of the hippocampus has been disputed. However, through serendipitous circumstances, the function of the hippocampus was discovered. In 1933 a young boy, H.M., experienced trauma to the head from a bicycle accident. Several years following the accident minor seizures ensued. As an adult, the seizures progressed to the point where he could not function normally on a day-today basis. The physicians of H.M.'s time realized that the MLT had epiletogenic qualities and strongly considered ablation to eliminate seizures. However, they did not understand the role of the MTL; by removing the MTL the ability to acquire new conscious memories is obliterated. Not being able to form new memories is known as anterograde amnesia. The hippocampal system enables explicit or declarative memory. Declarative memory encompasses the acquisition, retention, and retrieval of knowledge that can be consciously and intentionally recollected (Cohen and Squire 1980). Eichenbaum (1997) defines declarative memory as " the ability to bring facts and experiences to mind, that is, to consciously recall items in memory—and then to express the recalled memory in a variety of ways…by verbal reflection on a learned fact or past experience " (549). His research supports the theory of declarative memory being mediated by a brain circuit composed of distinct components in the cerebral cortex, parahippocampal region, and the hippocampus (568). H.M. could not form new memories and also had difficulties recalling items prior to his surgery. The loss of memory for events that occurred prior to brain damage is retrograde amnesia. Although, H.M.'s seizures were less frequent and severe, following the surgery he lost a significant amount of memory. He could not recognize the hospital staff or the hospital setting. " H.M.'s amnesia is characterized by several cardinal features: (a) intact perceptual, motor and cognition function; (b) intact immediate memory; (c) severe and global amnesia; (d) temporally graded retrograde amnesia; and (e) spared remote memory " (Eichenbaum & Cohen, 2001). Scientists discovered that …