Encoding, consolidation, and retrieval of contextual memory: differential involvement of dorsal CA3 and CA1 hippocampal subregions

Studies on human and animals shed light on the unique hippocampus contributions to relational memory. However, the particular role of each hippocampal subregion in memory processing is still not clear. Hippocampal computational models and theories have emphasized a unique function in memory for each hippocampal subregion, with the CA3 area acting as an autoassociative memory network and the CA1 area as a critical output structure. In order to understand the respective roles of the CA3- and CA1-hippocampal areas in the formation of contextual memory, we studied the effects of the reversible inactivation by lidocaine of the CA3 or CA1 areas of the dorsal hippocampus on acquisition, consolidation, and retrieval of a contextual fear conditioning. Whereas infusions of lidocaine never impaired elementary tone conditioning, their effects on contextual conditioning provided interesting clues about the role of these two hippocampal regions. They demonstrated first that the CA3 area is necessary for the rapid elaboration of a unified representation of the context. Secondly, they suggested that the CA1 area is rather involved in the consolidation process of contextual memory. Third, they showed that CA1 or CA3 inactivation during retention test has no effect on contextual fear retrieval when a recognition memory procedure is used. In conclusion, our findings point as evidence that CA1 and CA3 subregions of the dorsal hippocampus play important and different roles in the acquisition and consolidation of contextual fear memory, whereas they are not required for context recognition.     

Eye movements and the modulation of parafoveal processing by foveal processing difficulty: A reexamination

Henderson and Ferreira (1990) found that foveal load (manipulated via word frequency) modulates parafoveal processing, thereby affecting the amount of preview benefit obtained from the word to the right of fixation. The present experiment used the eye-contingent boundary paradigm and, consistent with Henderson and Ferreira, showed that foveal load modulated preview benefit for participants who were not aware of the display changes during reading. Also, for these participants, foveal load modulated preview benefit regardless of fixation durations on the foveal word. For participants who were aware of the display change, preview benefits occurred regardless of foveal processing difficulty. These results have important implications for understanding the way in which foveal load influences parafoveal processing during reading.     

Distinctiveness,typicality, and recollective experience in face recognition: A principal components analysis

In this study, participants rated previously unseen faces on six dimensions: familiarity, distinctiveness, attractiveness, memorability, typicality, and resemblance to a familiar person. The faces were then presented again in a recognition test in which participants assigned their positive recognition decisions to either remember (R), know (K), or guess categories. On all dimensions except typicality, faces that were categorized as R responses were associated with significantly higher ratings than were faces categorized as K responses. Study ratings for R and K responses were then subjected to a principal components analysis. The factor loadings suggested that R responses were influenced primarily by the distinctiveness of faces, but K responses were influenced by moderate ratings on all six dimensions. These findings indicate that the structural features of a face influence the subjective experience of recognition.     

Modulation of recognition and temporal order memory retrieval by dopamine D1 receptor in rats

The present study examines the effects of SKF 81297, a selective D1 agonist, on information retrieval in recognition and temporal order memory for objects, using three different tasks. Separate groups of rats were trained in each task and then given an intraperitoneal injection of saline or the D1 agonist (0.03, 0.3 mg/kg), before the memory testing trial in an object recognition, object location, and object temporal order memory tasks. We show that SKF 81297, at high dose (0.3 mg/kg), facilitates information retrieval after a long delay (4 h) in the three memory tasks whereas both high and low doses of D1 agonist impair recognition memory after a short delay (15 min). These results indicate a significant role of dopamine D1 receptors in recognition memory for both familiarity and place of objects in addition to object temporal order memory.     

Evidence that baroreflex feedback influences long-term incidental visual memory in men

Sympathetic nervous system (SNS) activity at the time of acquisition is associated with human memory. However, rather than SNS activity per se, it may be afferent baroreflex feedback that is responsible for this effect. A pharmacological design was employed to unload (SNP, sodium nitro-prusside) and load (norepinephrine) baroreceptors. In addition to two placebo periods, epinephrine and esmolol (a peripherally acting beta1-blocker) served as control conditions for altered cardiac perception. During drug infusion blood pressure, heart rate, and perception of heartbeat were tested. Twenty-four healthy men were participated. The participants viewed emotional slides while their electromyographic eye blink responses to random noise bursts were measured (affective startle modulation paradigm) to determine potential drug impact on emotional processing. Subjects were not informed that memory testing would take place after 4 weeks. Drugs did not impact startle, thus indicating unbiased emotional processing at the time of acquisition. Norepinephrine had no effect on heartbeat perception, but improved (p = .002) recognition memory. SNP (p = .0001) increased heartbeat perception but impaired (p = .038) recognition memory. Epinephrine, on the other hand, increased heartbeat perception (p = .0001) yet did not impair but partially improve memory (effect on high arousing pictures only: p = .05). Heartbeat perception in the placebo condition did not correlate with recognition memory (p's > .5). We suggest that baroreflex unloading, with subsequent feedback activation of the SNS, impairs long-term incidental visual recognition memory in humans while baroreflex loading enhances it. Further, we propose that these memory effects are neither secondary to cardiac sensations that accompany SNS activation nor to altered emotional picture processing at the time of acquisition.     

Body image ups and downs: prediction of intra-individual level and variability of women's daily body image experiences

This investigation assessed body image states in the context of everyday life among 108 college women. Participants initially completed measures of body image traits and eating attitudes and subsequently called an automated telephonic response system twice daily for 6 days to convey current body image experiences on the Body Image States Scale. The research examined the extent to which selected pretest variables predicted the level and variability of body image states. As hypothesized, less favorable body image state levels were associated with lower trait body image satisfaction, more body image dysphoria, more dysfunctional investment in appearance, more disturbed eating attitudes, and the use of less adaptive and more maladaptive body image coping strategies. Also as expected, body image variability was predicted by psychological investment in one's appearance, disturbed eating attitudes, and appearance-fixing coping strategies. Implications of the results and future research directions are discussed.     

The influence of writing practice on letter recognition in preschool children: a comparison between handwriting and typing

A large body of data supports the view that movement plays a crucial role in letter representation and suggests that handwriting contributes to the visual recognition of letters. If so, changing the motor conditions while children are learning to write by using a method based on typing instead of handwriting should affect their subsequent letter recognition performances. In order to test this hypothesis, we trained two groups of 38 children (aged 3-5 years) to copy letters of the alphabet either by hand or by typing them. After three weeks of learning, we ran two recognition tests, one week apart, to compare the letter recognition performances of the two groups. The results showed that in the older children, the handwriting training gave rise to a better letter recognition than the typing training.     

Temporal ventriloquism: sound modulates the flash-lag effect

A sound presented in close temporal proximity to a visual stimulus can alter the perceived temporal dimensions of the visual stimulus (temporal ventriloquism). In this article, the authors demonstrate temporal ventriloquism in the flash-lag effect (FLE), a visual illusion in which a flash appears to lag relative to a moving object. In Experiment 1, the magnitude and the variability of the FLE were reduced, relative to a silent condition, when a noise burst was synchronized with the flash. In Experiment 2, the sound was presented before, at, or after the flash (+/- approximately 100 ms), and the size of the FLE varied linearly with the delay of the sound. These findings demonstrate that an isolated sound can sharpen the temporal boundaries of a flash and attract its temporal occurrence.     

Time of day-dependent latent inhibition of conditioned taste aversions in rats

We have determined that the temporal context of drinking can modulate latent inhibition of learned saline aversions in Wistar rats by changing the time of day of drinking of the preexposure and conditioning phases. Latent inhibition was absent in the group preexposed and conditioned to saline at different times of the day, but not in the group that was preexposed and conditioned at the same time of day. The results confirm a previous report that the time of day can modulate taste aversion learning independently of other environmental cues. It is proposed that the features and duration of the habituation training to the temporal contexts used may be critical for time-dependent latent inhibition to appear.     

A revised methodology for research on metamemory: Pre-judgment Recall and Monitoring (PRAM)

A revised methodology is described for research on metacognitive monitoring, especially judgments of learning (JOLs), to investigate psychological processing that previously has been only hypothetical and unobservable. During data collection a new stage of recall occurs just prior to the JOL, so that during data analysis the items can be partitioned into subcategories to measure the degree of JOL accuracy in ways that are more analytic than was previously possible. A weighted-average combinatorial rule allows the component measures of JOL accuracy to be combined into the usual overall measure of metacognitive accuracy. An example using the revised methodology offers a new explanation for the delayed-JOL effect, in which delayed JOLs are more accurate than immediate JOLs for predicting recall.