Organization Of Memory Functions Research Articles

Introduction to the Special Issue

Suzanne Hammond grew up in the Hartford, Connecticut area, a childhood friend, as circumstance would have it, of the daughter of the surgeon William Beecher Scoville. From this, many readers will have already deduced that she also spent her youth in the same region as did the patient with whom she will always be associated: H.M. Indeed, as her soon-to-be-published book (Corkin, 2012) will no doubt relate, during laboratory interviews that were to take place over ensuing decades, Henry would sometimes opine (incorrectly) that she and he “might have gone to high school together.” Her scientific career began at McGill University, where she learned from and worked with some of the giants of neuroscience, including D. O. Hebb, Wilder Penfield, Herbert Jasper, Theodore Rasmussen, Robert Malmo, and of course, her mentor Brenda Milner. The importance of Corkin and Milner's pioneering investigations of domains of intact nondeclarative memory, despite impaired declarative memory in the anterograde amnesic syndrome, is placed in context by the contributions of Eichenbaum (2012) and of Nadel, Hoscheidt, and Ryan (2012) to this special issue.Dr. Milner's Foreword to this special issue offers a personal perspective on these early years in science (Milner, 2012) as well as on the legacy of Sue Corkin's career-long association with H.M. Serving as the other bookend of this special issue is Cronin-Golomb's (2012) collection of reminiscences from some of the many women who had the good fortune to have been mentored by Sue at various stages of their careers. From this piece, from sifting through the historical record, and from conversations with her contemporaries, one sees that throughout her career—and particularly in the 1960s and 1970s—Suzanne Corkin defined, through her daily comportment and accomplishments, a new model for how to be a successful woman in science. Certainly, many of her mentees and associates, including this writer, admire the aplomb with which she has balanced a productive career with the raising of a warm, loving family.Returning to her science and picking up where Milner (2012) leaves off, as Suzanne Corkin established her Behavioral Neuroscience Laboratory in the late 1970s, she began to pursue leading-edge research that defined the perceptual and cognitive profiles characteristic of neurodegenerative disorders, particularly Parkinson disease and Alzheimer disease. In parallel, she continued with her studies of H.M. and of other patients to advance our theoretical understanding of human memory functions. In the 1990s, she embraced emerging neuroimaging methods, publishing, for example, among the first fMRI studies characterizing the role of the hippocampal formation and medial-temporal lobe (MTL) in long-term memory encoding (Stern et al., 1996) and the definitive (in vivo) anatomical characterization of H.M.'s lesions (Corkin, Amaral, Gonzalez, Johnson, & Hyman, 1997). Both of these studies were influential in expanding the focus of human long-term memory research from the hippocampus proper to the broader MTL system. Throughout, she has also continued to contribute to the understanding of her first scientific passion, somatosensation. More recently, in the new millennium, she has made important contributions to the study of emotional memory and, with sophisticated imaging techniques, of age-related changes in the structure and function of the brain.Many of the articles assembled in this special issue address domains of cognitive neuroscience to which Suzanne Corkin has made important contributions: the functions of the hippocampus and MTL, the neural bases of perception and working memory, the organization of memory functions, the interaction of emotion and memory, and the effects of aging and of age-related neurodegenerative disease on cognition. All are contributed by individuals who have valued her as a mentor, collaborator, and/or colleague. Of necessity, only a sparse sampling of individuals from each group can be represented here.As she transitions into the next phase of her rich, passionate life, Dr. Suzanne Corkin's scientific career will be crowned with the early 2013 publication of her much-awaited book, Permanent Present Tense: The Unforgettable Life of the Amnesic Patient, H.M. How fitting a title from a scientist who has, herself, made so many unforgettable contributions to her field and to the scientists fortunate enough to have known her.Reprint requests should be sent to Bradley R. Postle, Department of Psychology, University of Wisconsin-Madison, 1202 W. Johnson St., Madison, WI 53706, or via e-mail: postle@wisc.edu.

Functional asymmetry of human prefrontal cortex: encoding and retrieval of verbally and nonverbally coded information.

There are several views about the organization of memory functions in the human prefrontal cortex. One view assumes a process-specific brain lateralization according to different memory subprocesses, that is, encoding and retrieval. An alternative view emphasizes content-specific lateralization of brain systems involved in memory processes. This study addresses this apparent inconsistency between process- and content-specific lateralization of brain activity by investigating the effects of verbal and nonverbal encoding on prefrontal activations during encoding and retrieval of environmental novel sounds using fMRI. An intentional memory task was applied in which subjects were required either to judge the sounds' loudness (nonverbal encoding task) or to indicate whether or not a sound can be verbally described (verbal encoding task). Retrieval processes were examined in a subsequent yes/no recognition test. In the study phase the right posterior dorsolateral prefrontal cortex (PFC) was activated in both tasks. During verbal encoding additional activation of the left dorsolateral PFC was obtained. Retrieval-related fMRI activity varied as a function of encoding task: For the nonverbal task we detected an activation focus in the right posterior dorsolateral PFC whereas an activation in the left dorsolateral PFC was observed for the verbal task. These findings indicate that the right dorsolateral PFC is engaged in encoding of auditory information irrespective of encoding task. The lateralization of PFC activity during retrieval was shown to depend on the availability of verbal codes, with left hemispheric involvement for verbally and right hemispheric activation for nonverbally coded information.

Episodic memory, semantic memory, and amnesia.

Episodic memory and semantic memory are two types of declarative memory. There have been two principal views about how this distinction might be reflected in the organization of memory functions in the brain. One view, that episodic memory and semantic memory are both dependent on the integrity of medial temporal lobe and midline diencephalic structures, predicts that amnesic patients with medial temporal lobe/diencephalic damage should be proportionately impaired in both episodic and semantic memory. An alternative view is that the capacity for semantic memory is spared, or partially spared, in amnesia relative to episodic memory ability. This article reviews two kinds of relevant data: 1) case studies where amnesia has occurred early in childhood, before much of an individual's semantic knowledge has been acquired, and 2) experimental studies with amnesic patients of fact and event learning, remembering and knowing, and remote memory. The data provide no compelling support for the view that episodic and semantic memory are affected differently in medial temporal lobe/diencephalic amnesia. However, episodic and semantic memory may be dissociable in those amnesic patients who additionally have severe frontal lobe damage.