Emotionally arousing pictures increase blood glucose levels and enhance recall

Arousal enhances memory in human participants and this enhancing effect is likely due to the release of peripheral epinephrine. As epinephrine does not readily enter the brain, one way that peripheral epinephrine may enhance memory is by increasing circulating blood glucose levels. The present study investigated the possibility that emotionally arousing color pictures would improve memory and elevate blood glucose levels in human participants. Blood glucose levels were measured before, 15 min, and 30 min after male university students viewed 60 emotionally arousing or relatively neutral pictures. Participants viewed each picture for 6 s and then had 10 s to rate the arousal (emotional intensity) and valence (pleasantness) of each picture. A free-recall memory test was given 30 min after the last picture was viewed. Although the emotionally arousing and neutral picture sets were given comparable valence ratings, participants who viewed the emotionally arousing pictures rated the pictures as being more arousing, recalled more pictures, and had higher blood glucose levels after viewing the pictures than did participants who viewed the neutral pictures. These findings indicate that emotionally arousing pictures increase blood glucose levels and enhance memory, and that this effect is not due to differences in the degree of pleasantness of the stimuli. These findings support the possibility that increases in circulating blood glucose levels in response to emotional arousal may be part of the biological mechanism that allows emotional arousal to enhance memory.     

Bridging the gap between brain and behavior: cognitive and neural mechanisms of episodic memory

The notion that non-human animals are capable of episodic memory is highly controversial. Here, we review recent behavioral work from our laboratory showing that the fundamental features of episodic memory can be observed in rats and that, as in humans, this capacity relies on the hippocampus. We also discuss electrophysiological evidence, from our laboratory and that of others, pointing to associative and sequential coding in hippocampal cells as potential neural mechanisms underlying episodic memory.     

Differential interaction of platelet-activating factor and NMDA receptor function in hippocampal and dorsal striatal memory processes

The interaction between platelet activating factor (PAF) and NMDA receptor function in hippocampal and dorsal striatal memory processes was examined. In both a hidden and a visible platform water maze task, peripheral post-training injection of MK-801 (0.05 mg/kg) impaired memory. Post-training intrahippocampal infusions of PAF (1.0 microg/0.5 microl) enhanced memory in the hidden platform task, while intradorsal striatal infusion of PAF (1.0 microg/0.5 microl) enhanced memory in the visible platform task. The memory impairing effects of post-training injection of MK-801 was blocked by concurrent intrahippocampal infusion of PAF. In contrast, post-training injection of MK-801 blocked the memory enhancing effects of concurrent intradorsal striatal infusion of PAF. The results suggest that (1) the memory enhancing effects of intracerebral PAF infusion involve an interaction with NMDA receptor function, and (2) the nature of this interaction may represent a differential mechanism mediating the distinct roles of the hippocampus and dorsal striatum in cognitive memory and stimulus-response habit formation, respectively.     

Training the brain: fact and fad in cognitive and behavioral remediation

Putatively safe and effective for improving cognitive performance in both health and disease, products purported to train the brain appeal to consumers and healthcare practitioners. In an increasingly health-centered society, these applications constitute a burgeoning commercial market. Sparse evidence coupled with lack of scientific rigor, however, leaves claims concerning the impact and duration of such brain training largely unsubstantiated. On the other hand, at least some scientific findings seem to support the effectiveness and sustainability of training for higher brain functions such as attention and working memory. In the present paper we provide a tectonic integration and synthesis of cognitive training approaches. Specifically, we sketch the relative merits and shortcomings of these programs, which often appeal to parents who must choose between side-effect-laden medication and other less conventional options. Here we examine how neuroplasticity allows the healthy as well the impaired to benefit from cognitive training programs. We evaluate the evidence and consider whether brain training can be a stand-alone treatment or an adjunct to pharmacotherapy, outline promising future prospects, and highlight what training outcomes are plausible in line with available data. Future research would determine whether the field of brain training realizes its potential to revolutionize education and rehabilitation or withers away engulfed in controversy.     

Egocentric metric representations in peripersonal space: A bridge between motor resources and spatial memory

Research on visuospatial memory has shown that egocentric (subject-to-object) and allocentric (object-to-object) reference frames are connected to categorical (non-metric) and coordinate (metric) spatial relations, and that motor resources are recruited especially when processing spatial information in peripersonal (within arm reaching) than extrapersonal (outside arm reaching) space. In order to perform our daily-life activities, these spatial components cooperate along a continuum from recognition-related (e.g., recognizing stimuli) to action-related (e.g., reaching stimuli) purposes. Therefore, it is possible that some types of spatial representations rely more on action/motor processes than others. Here, we explored the role of motor resources in the combinations of these visuospatial memory components. A motor interference paradigm was adopted in which participants had their arms bent behind their back or free during a spatial memory task. This task consisted in memorizing triads of objects and then verbally judging what was the object: (1) closest to/farthest from the participant (egocentric coordinate); (2) to the right/left of the participant (egocentric categorical); (3) closest to/farthest from a target object (allocentric coordinate); and (4) on the right/left of a target object (allocentric categorical). The triads appeared in participants' peripersonal (Experiment 1) or extrapersonal (Experiment 2) space. The results of Experiment 1 showed that motor interference selectively damaged egocentric-coordinate judgements but not the other spatial combinations. The results of Experiment 2 showed that the interference effect disappeared when the objects were in the extrapersonal space. A third follow-up study using a within-subject design confirmed the overall pattern of results. Our findings provide evidence that motor resources play an important role in the combination of coordinate spatial relations and egocentric representations in peripersonal space.     

Regional brain activity in dyslexic and control children during reading tasks: Visual probe event-related potentials

Event-related potentials (ERPs) elicited by task-irrelevant visual stimuli were recorded from 34 control and 32 dyslexic 10- to 12-year-old boys while they performed silent and oral reading at two levels of difficulty. All subjects were extensively screened for neurological problems, IQ, and sensory acuity. Specific features of the ERPs were affected in amplitude and latency by the experimental variables: group membership, oral vs. silent reading, difficulty level, and recording site (within and between hemispheres). A specific effect of difficulty on the central and parietal ERP was seen in the dyslexics but not the controls. Different patterns of asymmetry were found for the two groups in silent vs. oral reading at midtemporal placements. A marked asymmetry (R > L) was found at the midtemporal region for both groups.     

The memory is in the details: Relations between memory for the specific features of events and long-term recall during infancy

The second year of life is marked by pronounced changes in the length of time over which events are remembered. We tested whether the age-related differences are related to differences in memory for the specific features of events. In our study, 16- and 20-month-olds were tested for immediate and long-term recall of individual actions and temporal order of actions of three-step sequences in an elicited imitation paradigm as well as for forced-choice recognition of the specific feature of the props used to produce the sequences. Memory for the props was related to long-term recall of the events only for the 20-month-olds. It accounted for unique variance above and beyond the variance explained by immediate recall of the individual actions and the temporal order of actions of the sequences. The different pattern of relations in the older and younger infants seemingly reflects a developmental difference in the determinants of long-term recall over the second year of life.     

Stuttering and anxiety: The difference between stutterers and nonstutterers in verbal apprehension and physiologic arousal during the anticipation of speech and non-speech tasks

To test if stressful anticipation of speech situations is a factor in eliciting stuttering behavior, the difference between 24 stutterers and 24 nonstutterers in verbal apprehension and physiologic activity was studied before and during speech tasks (reading and conversation), and nonspeech tasks (motor and intelligence task).Results indicate that the difference between stutterers and nonstutterers mainly were restricted to anxiety ratings assessed after each task. Heart rate, vasomotor responses, and electrodermal activity recorded before and during speech tasks were higher compared with the physiologic activity before and during nonspeech tasks but, unexpectedly, this was also the case for nonstutterers. It is concluded that stuttering is not elicited by anxiety.