Bilateral eye movements enhance the retrieval of episodic memories.

Two experiments examining effects of eye movements on episodic memory retrieval are reported. Thirty seconds of horizontal saccadic eye movements (but not smooth pursuit or vertical eye movements) preceding testing resulted in selective enhancement of episodic memory retrieval for laboratory (Experiment 1) and everyday (Experiment 2) events. Eye movements had no effects on implicit memory. Eye movements were also associated with more conservative response biases relative to a no eye movement condition. Episodic memory improvement induced by bilateral eye movements is hypothesized to reflect enhanced interhemispheric interaction, which is associated with superior episodic memory (S. D. Christman & R. E. Propper. 2001). Implications for neuropsychological mechanisms underlying eye movement desensitization and reprocessing (F. Shapiro, 1989, 2001), a therapeutic technique for posttraumatic stress disorder, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Building memories: remembering and forgetting of verbal experiences as predicted by brain activity

A fundamental question about human memory is why some experiences are remembered whereas others are forgotten. Brain activation during word encoding was measured using blocked and event-related functional magnetic resonance imaging to examine how neural activation differs for subsequently remembered and subsequently forgotten experiences. Results revealed that the ability to later remember a verbal experience is predicted by the magnitude of activation in left prefrontal and temporal cortices during that experience. These findings provide direct evidence that left prefrontal and temporal regions jointly promote memory formation for verbalizable events.     

Involuntary movements and birth injuries to brain

OBJECTIVE: To evaluate the effect of using an optimally adjusted fixed ankle foot orthosis to control knee pain and promote improvement in gait parameters in a subject with hemiplegia following a traumatic brain injury 11 years previously. DESIGN: This is the report of a single case, using gait laboratory facilities to monitor force alignment relative to the knee and single leg balance time with the subject barefoot. SUBJECT: A 35-year-old woman with a right hemiplegia seen 11 years after onset. INTERVENTION: A polypropylene fixed ankle foot orthosis was supplied to the hemiplegic limb and shoe modifications were made to optimize the position of the ground reaction force relative to the knee during stance phase of gait. This orthosis was used on a daily basis for one year. RESULTS: Knee pain was controlled after three months use of the orthosis. Graphical results of force alignment during stance phase of gait are presented for initial assessment and at one and four years postorthotic supply. A large knee-extending effect was noted on the hemiplegic limb at initial assessment and this was reduced by 67% of its initial value at one year. A compensatory early heel lift was initially noted on the opposite limb and this was reduced by 42% of the initial height at one year. These results were maintained at four years. Right leg standing balance was not initially possible but was recorded as 5 s duration at three months and this was maintained at one and at four years. CONCLUSIONS: The use of an optimally adjusted ankle foot orthosis was effective in controlling knee pain and improving barefoot gait parameters with maintenance of the improvement after use of the orthosis was discontinued. Further research is required to fully establish the potential of this approach in subjects with traumatic brain injury.     

Recovered memories and false memories.

Review of book: Recovered Memories and False Memories by Martin A. Conway, New York: Oxford University Press, 1997, 301 pp. Reviewed by C. Brooks Brenneis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Making memories: brain activity that predicts how well visual experience will be remembered

Experiences are remembered or forgotten, but the neural determinants for the mnemonic fate of experience are unknown. Event-related functional magnetic resonance imaging was used to identify specific brain activations that differentiated between visual experiences that were later remembered well, remembered less well, or forgotten. During scanning of medial temporal lobe and frontal lobe regions, subjects viewed complex, color photographs. Subjects later received a test of memory for the photographs. The magnitudes of focal activations in right prefrontal cortex and in bilateral parahippocampal cortex predicted which photographs were later remembered well, remembered less well, or forgotten.     

Effects of p-chlorophenylalanine-induced depletion of brain serotonin on retrieval of appetitive and aversive memories

This study examined whether depletion of central serotonin produces an improved retrieval of aversive memories in the same way as pre-exposure to inescapable footshocks, in rats. Animals conditioned in a T-maze with appetitive (10% sucrose) and aversive (2.0 mA footshock) events were given i.c.v. 24 hr later a single dose of p-chlorophenylalanine (p-CPA). (100, 200, 400 micrograms/rat) or drug vehicle. The retention performance and activity were assessed 48 hr after treatment with this depletor. While lower doses of p-CPA selectively reduced serotonin levels in striatum and anterior cortex, higher doses reduced both serotonin and norepinephrine levels in hippocampus in a dose-dependent fashion. The depletor however, failed to produce a differential improvement of aversive memory retrieval. On the contrary, p-CPA reduced the latency to enter both, previously shocked and appetitively reinforced, goalboxes. The enhanced traversing behaviour in T-maze, together with an increased central entry in the open field that observed in depleted groups, might suggest an anxiolytic activity of p-CPA.     

Does the brain use sliding variables for the control of movements?

Delays in the transmission of sensory and motor information prevent errors from being instantaneously available to the central nervous system (CNS) and can reduce the stability of a closed-loop control strategy. On the other hand, the use of a pure feedforward control (inverse dynamics) requires a perfect knowledge of the dynamic behavior of the body and of manipulated objects. Sensory feedback is essential both to accommodate unexpected errors and events and to compensate for uncertainties about the dynamics of the body. Experimental observations concerning the control of posture, gaze and limbs have shown that the CNS certainly uses a combination of closed-loop and open-loop control. Feedforward components of movement, such as eye saccades, occur intermittently and present a stereotyped kinematic profile. In visuo-manual tracking tasks, hand movements exhibit velocity peaks that occur intermittently. When a delay or a slow dynamics are inserted in the visuo-manual control loop, intermittent step-and-hold movements appear clearly in the hand trajectory. In this study, we investigated strategies used by human subjects involved in the control of a particular dynamic system. We found strong evidence for substantial nonlinearities in the commands produced. The presence of step-and-hold movements seemed to be the major source of nonlinearities in the control loop. Furthermore, the stereotyped ballistic-like kinematics of these rapid and corrective movements suggests that they were produced in an open-loop way by the CNS. We analyzed the generation of ballistic movements in the light of sliding control theory assuming that they occurred when a sliding variable exceeded a constant threshold. In this framework, a sliding variable is defined as a composite variable (a combination of the instantaneous tracking error and its temporal derivatives) that fulfills a specific stability criterion. Based on this hypothesis and on the assumption of a constant reaction time, the tracking error and its derivatives should be correlated at a particular time lag before movement onset. A peak of correlation was found for a physiologically plausible reaction time, corresponding to a stable composite variable. The direction and amplitude of the ongoing stereotyped movements seemed also be adjusted in order to minimize this variable. These findings suggest that, during visually guided movements, human subjects attempt to minimize such a composite variable and not the instantaneous error. This minimization seems to be obtained by the execution of stereotyped corrective movements.     

Repressed memories: Avoiding the obvious.

Sorting out the distinctions between reality and fantasy in terms of apparently recovered memories and reconstructions is at least as puzzling as sorting out current realities. In responding to C. B. Brenneis's (see records 2007-10660-001 and 2001-07368-001) challenge to the existence of the phenomena of repression and of recovered or reconstructed memories, the authors point out the data from the Recovered Memory Archive web site, the data from World War I and World War II battlefield neuroses, as well as the clinical observations of psychoanalysts. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repressed memories: Just the facts.

Responding to comments by S. O. Lilienfeld and E. F. Loftus (see record 1999-01568-013) and M. Pendergrast (see record 1999-01568-014), the authors discuss the evidence supporting the existence of repressed–recovered memories rather than specifically addressing what they see as distortions of their past research. Karon and Widener state that repression is one of the coping mechanisms people use to survive that must be included in the clinical understanding of the dynamics of repression and recovered memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Desperately seeking memories of the first few years of childhood: The reality of early memories.

How far back into their childhoods can people remember? Previous research suggests that people's earliest memories date back to the ages of 3 or 4 yrs. J. A. Usher and U. Neisser (see record 1993-36251-001) reported that some events, like the birth of a sibling and a planned hospitalization, can be readily remembered if they occurred at age 2 yrs. However, the bits and pieces of such memories that were obtained in their research may not be indicative of genuine episodic memory. An alternative hypothesis is that these apparent memories are the result of educated guesses, general knowledge of what must have been, or external information acquired after the age of 2 yrs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovered memories of trauma: phenomenology and cognitive mechanisms

We outline four current explanations for the reported forgetting of traumatic events, namely repression, dissociation, ordinary forgetting, and false memory. We then review the clinical and survey evidence on recovered memories, and consider experimental evidence that a variety of inhibitory processes are involved in everyday cognitive activity including forgetting. The data currently available do not allow any of the four explanations to be rejected, and strongly support the likelihood that some recovered memories correspond to actual experiences. We propose replacing the terms repression and dissociation as explanations of forgetting with an account based on cognitive science.     

Repression and the inaccessibility of affective memories.

Examined 3 groups of Ss (repressors, low anxious, and high anxious) under 6 conditions of recall (general, happy, sad, anger, fear, and wonder). Ss were asked to recall personal experiences from childhood and to rate their current mood and the affective intensity of the memories. Repressors recalled significantly fewer negative memories than did low-anxious and high-anxious Ss and were substantially older at the time of the earliest negative memory recalled. Compared with low-anxious Ss, repressors also recalled fewer positive affective memories as well. This pattern of findings is consistent with the hypothesis that repression involves an inaccessibility to negative emotional memories and indicates further that repression is associated in some way with the suppression or inhibition of emotional experiences in general. The concept of repression as a process involving limited access to negative affective memories appears to be valid. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repression and the inaccessibility of affective memories.

Fundamental to the concept of repression is the proposition that repression serves to keep painful, unpleasant experiences out of consciousness or awareness. If this is indeed true, then individuals who characteristically use repression as a defensive strategy should have less access to emotional memories, especially those of negative, unpleasant events. The three studies presented here address this proposition. Repressors, operationally defined by a pattern of low anxiety and high defensiveness, displayed a limited accessibility to personal, real-life affective memories that was particularly pronounced for fear and self-consciousness experiences. Furthermore, recall of emotional experiences of self versus other revealed that the effects of repression were specific to emotional experiences of the self. The overall pattern of findings suggests that repression may be motivated, in particular, by affective experiences that focus attention on the self in a threatening or evaluative way. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term memory for the terrorist attack of September 11: Flashbulb memories, event memories, and the factors that influence their retention.

More than 3,000 individuals from 7 U.S. cities reported on their memories of learning of the terrorist attacks of September 11, as well as details about the attack, 1 week, 11 months, and/or 35 months after the assault. Some studies of flashbulb memories examining long-term retention show slowing in the rate of forgetting after a year, whereas others demonstrate accelerated forgetting. This article indicates that (a) the rate of forgetting for flashbulb memories and event memory (memory for details about the event itself) slows after a year, (b) the strong emotional reactions elicited by flashbulb events are remembered poorly, worse than nonemotional features such as where and from whom one learned of the attack, and (c) the content of flashbulb and event memories stabilizes after a year. The results are discussed in terms of community memory practices. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Misinformation and memory: The creation of new memories.

Misleading information presented after an event can lead people to erroneous reports of that misinformation. Different process histories can be responsible for the same erroneous report in different people. We argue that the relative proportion of times that the different process histories are responsible for erroneous reporting will depend on the conditions of acquisition, retention, and retrieval of information. Given the conditions typical of most misinformation experiments, it appears that misinformation acceptance plays a major role, memory impairment plays some role, and pure guessing plays a little or no role. Moreover, we argue that misinformation acceptance has not received the appreciation that it deserves as a phenomenon worthy of our sustained investigation. It may not tell us anything about impairment of memories, but it does tell us something about the creation of new memories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adults' memories of childhood: True and false reports.

In 3 experiments, the authors examined factors that, according to the source-monitoring framework, might influence false memory formation and true/false memory discernment. In Experiment 1, combined effects of warning and visualization on false childhood memory formation were examined, as were individual differences in true and false childhood memories. Combining warnings and visualization led to the lowest false memory and highest true memory. Several individual difference factors (e.g., parental fearful attachment style) predicted false recall. In addition, true and false childhood memories differed (e.g., in amount of information). Experiment 2 examined relations between Deese/Roediger-McDermott task performance and false childhood memories. Deese/Roediger-McDermott performance (e.g., intrusion of unrelated words in free recall) was associated with false childhood memory, suggesting liberal response criteria in source decisions as a common underlying mechanism. Experiment 3 investigated adults' abilities to discern true and false childhood memory reports (e.g., by detecting differences in amount of information as identified in Experiment 1). Adults who were particularly successful in discerning such reports indicated reliance on event plausibility. Overall, the source-monitoring framework provided a viable explanatory framework. Implications for theory and clinical and forensic interviews are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)