Declarative memories

Sleep transforms the cerebral trace of declarative memories
Steffen Gais, Geneviève Albouy, Mélanie Boly, Thien Thanh Dang-Vu, Annabelle Darsaud, Martin Desseilles, Géraldine Rauchs, Manuel Schabus, Virginie Sterpenich, Gilles Vandewalle, Pierre Maquet, and Philippe Peigneux
PNAS, November 20, 2007, vol. 104, no. 47, 18778-18783.

After encoding, memory traces are initially fragile and have to be reinforced to become permanent. The initial steps of this process occur at a cellular level within minutes or hours. Besides this rapid synaptic consolidation, systems consolidation occurs within a time frame of days to years. For declarative memory, the latter is presumed to rely on an interaction between different brain regions, in particular the hippocampus and the medial prefrontal cortex (mPFC). Specifically, sleep has been proposed to provide a setting that supports such systems consolidation processes, leading to a transfer and perhaps transformation of memories. Using functional MRI, we show that postlearning sleep enhances hippocampal responses during recall of word pairs 48 h after learning, indicating intrahippocampal memory processing during sleep. At the same time, sleep induces a memory-related functional connectivity between the hippocampus and the mPFC. Six months after learning, memories activated the mPFC more strongly when they were encoded before sleep, showing that sleep leads to long-lasting changes in the representation of memories on a systems level.

Remembering the good times

Remembering the good times: neural correlates of affect regulation.
Cooney Rebecca E., Joormann Jutta, Atlas Lauren Y,Eugene Fanny, Gotlib, Ian H.
Neuroreport. 18(17):1771-1774, November 19, 2007.

Background:The ability to regulate one's mood state effectively is critical to emotional and physical health. Recent investigations have sought to delineate the neural mechanisms by which individuals regulate mood states and emotions, positing a critical role of a dorsal system that includes the dorsolateral prefrontal cortex and anterior cingulate.

Methods: This study extended these efforts by examining the neural correlates of retrieving positive autobiographical memories while experiencing a negative mood state in a sample of healthy female adults.

Results: We demonstrated that mood-incongruent recall is associated with activation in ventrolateral and ventromedial prefrontal cortices (including orbitofrontal cortex and subgenual cingulate).

Conclusions:These findings suggest that mood-incongruent recall differs from other affect regulation strategies by influencing mood through a ventral regulatory network.

Vilayanur Ramachandran: A journey to the center of your mind

(from TED) In a wide-ranging talk, Vilayanur Ramachandran explores how brain damage can reveal the connection between the internal structures of the brain and the corresponding functions of the mind. He talks about phantom limb pain, synesthesia (when people hear color or smell sounds), and the Capgras delusion, when brain-damaged people believe their closest friends and family have been replaced with imposters.

Think positive

Neural mechanisms mediating optimism bias.
Sharot T, Riccardi AM, Raio CM, Phelps EA.
Nature. 2007 Nov 1;450(7166):102-5

Background: Humans expect positive events in the future even when there is no evidence to support such expectations. For example, people expect to live longer and be healthier than average, they underestimate their likelihood of getting a divorce, and overestimate their prospects for success on the job market.

Methods: We examined how the brain generates this pervasive optimism bias. Here we report that this tendency was related specifically to enhanced activation in the amygdala and in the rostral anterior cingulate cortex when imagining positive future events relative to negative ones, suggesting a key role for areas involved in monitoring emotional salience in mediating the optimism bias.

Results: These are the same regions that show irregularities in depression, which has been related to pessimism. Across individuals, activity in the rostral anterior cingulate cortex was correlated with trait optimism.

Conclusion: The current study highlights how the brain may generate the tendency to engage in the projection of positive future events, suggesting that the effective integration and regulation of emotional and autobiographical information supports the projection of positive future events in healthy individuals, and is related to optimism.

Resolving emotional conflict

Dissociated responses in the amygdala and orbitofrontal cortex to bottom-up and top-down components of emotional evaluation.
Wright P, Albarracin D, Brown RD, Li H, He G, Liu Y.
Neuroimage. 2007 Sep 19

Background: Although emotional responses to stimuli may be automatic, explicit evaluation of emotion is a voluntary act. These bottom-up and top-down processes may be supported by distinct neural systems. Previous studies reported bottom-up responses in the amygdala, top-down responses in the orbital and ventromedial prefrontal cortices, and top-down modulation of the amygdalar response.

Methods: The current study used event-related fMRI on fifteen healthy males to examine these responses in the absence of stimulus anticipation or task repetition. Factorial analysis distinguished bottom-up responses in the amygdala from top-down responses in the orbitofrontal cortex.

Results: Activation of ventromedial prefrontal cortex and modulation of amygdalar response were not observed, and future studies may investigate whether these effects are contingent upon anticipation or cognitive set.

Sleep loss linked to psychiatric disorders

The human emotional brain without sleep — a prefrontal amygdala disconnect
Yoo SS, Gujar N, Hu P, Jolesz FA & Walker MP.
Current Biology 2007; 17(20): 877-878.

It has long been assumed that sleep deprivation can play havoc with our emotions.

Sleep deprivation is known to impair a range of functions, including immune regulation and metabolic control, as well as neurocognitive processes, such as learning and memory. But evidence for the role of sleep in regulating our emotional brain-state is surprisingly scarce, and while the dysregulation of affective stability following sleep loss has received subjective documentation, any neural examination remains absent. Clinical evidence suggests that sleep and emotion interact; nearly all psychiatric and neurological disorders expressing sleep disruption display corresponding symptoms of affective imbalance. Independent of sleep, knowledge of the basic neural and cognitive mechanisms regulating emotion is remarkably advanced. The amygdala has a well-documented role in the processing of emotionally salient information, particularly aversive stimuli. The extent of amygdala engagement can also be influenced by a variety of connected systems, particularly the medial-prefrontal cortex (MPFC); the MPFC is proposed to exert an inhibitory, top-down control of amygdala function, resulting in contextually appropriate emotional responses [5, 6]. We have focused on this network and using functional magnetic resonance image (fMRI) have obtained evidence, reported here, that a lack of sleep inappropriately modulates the human emotional brain response to negative aversive stimuli.

Negative emotion

How Negative Emotion Enhances the Visual Specificity of a Memory
Elizabeth A. Kensinger, Rachel J. Garoff-Eaton and Daniel L. Schacter
Journal of Cognitive Neuroscience, 19, 1872-1887

Background: Some studies have suggested that emotion primarily increases memory for "gist," and does not enhance memory for detail. There are, however, some instances in which negative objects (e.g., snake, grenade) are remembered with more visual detail than neutral objects (e.g., barometer, blender).

Methods: In the present functional magnetic resonance imaging (fMRI) study, we examined the encoding processes that lead a person to remember the exact visual details of negative and neutral objects, and to remember which of two decisions were made about the objects (a size decision or an animacy decision).

Results: The enhancement in memory for a negative item's visual details appeared to result from enhanced visual processing: The right fusiform gyrus, a region known to be critical for processing exemplar-specific details, showed a greater extent and magnitude of activity during the successful encoding of negative objects. Activity in the right amygdala also corresponded with memory for visual detail, although it did not relate to memory for the task performed with the item.

Conclusions: These data provide strong evidence that engagement of some amygdalar regions can correspond with enhanced memory for certain types of details, but does not ensure successful encoding of all contextual details.

The Power of Birth Order

Excellent article in the latest TIME magazine by Dan Cray.

"Of all the things that shape who we are, few seem more arbitrary than the sequence in which we and our siblings pop out of the womb. Maybe it's your genes that make you a gifted athlete, your training that makes you an accomplished actress, an accident of brain chemistry that makes you a drunk instead of a President. But in family after family, case study after case study, the simple roll of the birth-date dice has an odd and arbitrary power all its own.

The importance of birth order has been known—or at least suspected—for years. But increasingly, there's hard evidence of its impact."

Link to Time article 'The Power of Birth Order'.

10 Unsolved Mysteries Of The Brain

The Mind & Brain section of Discover magazine had a fantastic article on the mysteries of brain by David Eagleman.

"What we know—and don’t know—about how we think."

1. How is information coded in neural activity?
Neurons, the specialized cells of the brain, can produce brief spikes of voltage in their outer membranes. These electrical pulses travel along specialized extensions called axons to cause the release of chemical signals elsewhere in the brain.

2. How are memories stored and retrieved?
When you learn a new fact, like someone’s name, there are physical changes in the structure of your brain. But we don’t yet comprehend exactly what those changes are, how they are orchestrated across vast seas of synapses and neurons, how they embody knowledge, or how they are read out decades later for retrieval.

3. What does the baseline activity in the brain represent?
Neuroscientists have mostly studied changes in brain activity that correlate with stimuli we can present in the laboratory, such as a picture, a touch, or a sound. But the activity of the brain at rest—its “baseline” activity—may prove to be the most important aspect of our mental lives. The awake, resting brain uses 20 percent of the body’s total oxygen, even though it makes up only 2 percent of the body’s mass.

4. How do brains simulate the future?
The awake state may be essentially the same as the dreaming state. In this view, your conscious life is an awake dream.

5. What are emotions?
We often talk about brains as information-processing systems, but any account of the brain that lacks an account of emotions, motivations, fears, and hopes is incomplete.

6. What is intelligence?
Intelligence comes in many forms, but it is not known what intelligence—in any of its guises—means biologically. How do billions of neurons work together to manipulate knowledge, simulate novel situations, and erase inconsequential information? What happens when two concepts “fit” together and you suddenly see a solution to a problem? What happens in your brain when it suddenly dawns on you that the killer in the movie is actually the unsuspected wife? Do intelligent people store knowledge in a way that is more distilled, more varied, or more easily retrievable?

7. How is time represented in the brain?
When it comes to awareness, the brain goes through a good deal of trouble to synchronize incoming signals that are processed at very different speeds.

8. Why do brains sleep and dream?
One of the most astonishing aspects of our lives is that we spend a third of our time in the strange world of sleep. Newborn babies spend about twice that. It is inordinately difficult to remain awake for more than a full day-night cycle. In humans, continuous wakefulness of the nervous system results in mental derangement; rats deprived of sleep for 10 days die. All mammals sleep, reptiles and birds sleep, and voluntary breathers like dolphins sleep with one brain hemisphere dormant at a time. The evolutionary trend is clear, but the function of sleep is not.

9. How do the specialized systems of the brain integrate with one another?
To the naked eye, no part of the brain’s surface looks terribly different from any other part. But when we measure activity, we find that different types of information lurk in each region of the neural territory. There is no special anatomical location in the brain where information from all the different systems converges; rather, the specialized areas all interconnect with one another, forming a network of parallel and recurring links.

10. What is consciousness?
Think back to your first kiss. The experience of it may pop into your head instantly. Where was that memory before you became conscious of it? How was it stored in your brain before and after it came into consciousness? What is the difference between those states. The mechanisms underlying consciousness could reside at any of a variety of physical levels: molecular, cellular, circuit, pathway, or some organizational level not yet described.

Click here to read the entire story.

Brain Gardening

Blocking a brain chemical in some people with mental retardation makes their neurons grow like health plants. Watch the video about MIT research work on this from Discover magazine.


NeuroPod is the neuroscience podcast from Nature, produced in association with the Dana Foundation. Each month, Kerri Smith will be delving into the latest research on the brain, from its molecular makings to the mysteries of the mind.

In the first show, Kerri Smith explores the latest neuroscience research from Nature: untangling autism, slimming down obesity, getting emotional about memories, multipurpose ion channels, and neuroeconomics. Link

Alternatively, to ensure you do not miss any further issues of NeuroPod, you can subscribe to their free RSS feed. This way it will be delivered straight to your desktop! To do this, copy and paste the following URL into a media player such as iTunes:

Caring for children with sleep problems

Ward TM, Rankin S, Lee KA.
J Pediatr Nurs 2007;22(4):283-96.

Sleep disturbances are common in infants and children. Sleep disturbances in children not only disrupt the child and family but also impact parental and child well-being, daytime functioning, and behavior. Pediatric nurses care for the individual child as well as their family members. Understanding the importance of healthy sleep habits and the implications of inadequate sleep on child behavior and family-peer interactions provides nurses an opportunity to decrease family stress and increase positive coping, adaptation, and family function. Common types of sleep problems are presented, and recommendations for screening tools are included to help nurses better assess sleep problems in children and make appropriate referrals.

Curry your Brain

A chemical in the spice turmeric, used widely in Indian food, could help ward off Alzheimer's.

SWS and recollection in recognition memory

Daurat A, Terrier P, Foret J, Tiberge M.
Conscious Cogn 2007;16(2):445-55.

Recognition memory performance reflects two distinct memory processes: a conscious process of recollection, which allows remembering specific details of a previous event, and familiarity, which emerges in the absence of any conscious information about the context in which the event occurred. Slow wave sleep (SWS) and rapid eye movement (REM) sleep are differentially involved in the consolidation of different types of memory. The study assessed the effects of SWS and REM sleep on recollection, by means of the "remember"/"know" paradigm. Subjects studied three blocks of 12 words before a 3-h retention interval filled with SWS, REM sleep or wakefulness, placed between 3 a.m. and 6 a.m. Afterwards, recognition and recollection were tested. Recollection was higher after a retention interval rich in SWS than after a retention interval rich in REM sleep or filled with wakefulness. The results suggest that SWS facilitates the process of recollection in recognition memory.

Do you think you sleep?

Graciela E. Silva,James L. Goodwin,Duane L. Sherrill,Jean L. Arnold,Richard R. Bootzin, Terry Smith, Joyce A. Walsleben,Carol M. Baldwin,Stuart F. Quan
Journal of Clinical Sleep Medicine 2007;3(6):622-630.

Background: Subjective and objective assessments of sleep may be discrepant due to sleep misperception and measurement effects, the latter of which may change the quality and quantity of a person’s usual sleep. This study compared sleep times from polysomnography (PSG) with self-reports of habitual sleep and sleep estimated on the morning after a PSG in adults.

Methods: Total sleep time and sleep onset latency obtained from unattended home PSGs were compared to sleep times obtained from a questionnaire completed before the PSG and a Morning Survey completed the morning after the PSG.

Results: A total of 2,113 subjects who were ≥ 40 years of age were included in this analysis. Subjects were 53% female, 75% Caucasian, and 38% obese. The mean habitual sleep time (HABTST), morning estimated sleep time (AMTST), and PSG total sleep times (PSGTST) were 422 min, 379 min, and 363 min, respectively. The mean habitual sleep onset latency, morning estimated sleep onset latency, and PSG sleep onset latency were 17.0 min, 21.8 min, and 16.9 min, respectively. Models adjusting for related demographic factors showed that HABTST and AMTST differ significantly from PSGTST by 61 and 18 minutes, respectively. Obese and higher educated people reported less sleep time than their counterparts. Similarly, small but significant differences were seen for sleep latency.

Conclusions: In a community population, self-reported total sleep times and sleep latencies are overestimated even on the morning following overnight PSG.

Early phase in human brain development

Resting-state networks in the infant brain.
Peter Fransson, Beatrice Skiold, Sandra Horsch, Anders Nordell, Mats Blennow, Hugo Lagercrant and Ulrika Åden.
PNAS, September 25,2007,vol.104, no.39, 15531–15536

Background: In the absence of any overt task performance, it has been shown that spontaneous, intrinsic brain activity is expressed as systemwide, resting-state networks in the adult brain. However, the route to adult patterns of resting-state activity through neuronal development in the human brain is currently unknown.

Methods: 12 infants were scanned at term-equivalent age during sleep for 10 min. The total scanning time was 45–50 min. Functional MRI was used to map patterns of resting-state activity in infants during sleep. Physiologically relevant resting-state networks across subjects were extracted by using ICA.

Results: They found five unique resting-states networks in the infant brain that encompassed the primary visual cortex, bilateral sensorimotor areas, bilateral auditory cortex, a network including the precuneus area, lateral parietal cortex, and the cerebellum as well as an anterior network that incorporated the medial and dorsolateral prefrontal cortex.

Conclusions: The results suggest that resting-state networks driven by spontaneous signal fluctuations are present already in the infant brain. The potential link
between the emergence of behavior and patterns of resting-state activity in the infant brain is discussed.

Authorship Dilemma - Scientific Misconduct

Physicists do it by the hundred; scientists do it in groups; fiction writers mostly alone. And researchers? Rarely now do they write papers alone, and the number of authors on papers is ever increasing. However, the puzzling question here is who is the first author ?

The operative word here is "boss". It's his/her final decision. People get "cheated" out of first authorship all the time.

I agree to some extent when others that say it should be your boss's decision, although I think it is pretty lousy and unfortunately, we don't have any guidelines to go by. The lab politics and professional courtesy should not affect rewarding hard or tedious work which essentially should be looked at in the authorship decision. I don't think it's fine as long as your boss/PI spells out the exact contributions of each author in his/her letter of recommendation when it comes time for you to apply for jobs. Since according to me that seems like a small consolation although atleast it ensures you get appropriate credit with the people who matter most (especially potential future employers).

In most cases first authorship should be given to the person who did the most work, with the various types of work weighted by their values. Some work is more valuable than other. Generally, designing the research and writing the manuscript are considered more valuable than doing the statistical analysis, which is considered more valuable than collecting the data.

In this era of team-driven science I think the whole importance to the concept of first author is absurd. In fact, some journals require a final statement about the contribution of each author. I guess the tentative fix is that each author's contributions should be listed or acknowledged upon submission in every journal.

Whether or not scientific societies develop authorship policies of their own, they should undertake vigorous educational efforts to keep their new members adequately informed about the importance of authorship practices in ethical scientific research and publication. Since, it's all about research integrity.

References to articles on this topic
- APA Monitor Article, "The Authorship Dilemma," Dec., 1998
- Fine and Kurdek, American Psychologist, 48:1141-1147
- Costa and Gatz, Psychological Science, 3:354-357.
- Louw and Fouché, South African Journal of Psychology, 29:145-148.

Americans are Trading Sleep for Work and Gridlock

For many people, the American dream means owning a big house with an even bigger yard and a couple of attractive cars in the driveway. But what sacrifices are we willing to make in order to realize these super-sized dreams? A new study finds that sleep may be one of them: working long hours and being stuck in traffic appears to be keeping many Americans from their sleep. The study was based on the results of a federal telephone time-use survey of more than 47,000 Americans conducted from 2003 to 2005. The results showed that the amount of time spent working is the most important factor in determining how much Americans sleep. Time spent traveling, including those frustrating hours in gridlock, comes in second place.

American Time Use Survey: Sleep Time and Its Relationship to Waking Activities
Mathias Basner, MD, MSc; Kenneth M. Fomberstein; Farid M. Razavi; Siobhan Banks,PhD; Jeffrey H. William; Roger R. Rosa, PhD; David F. Dinges, PhD

To gain some insight into how various behavioral (lifestyle) factors influence sleep duration, by investigation of the relationship of sleep time to waking activities using the American Time Use Survey (ATUS).

Methods: Cross-sectional data from ATUS, an annual telephone survey of a population sample of US citizens who are interviewed regarding how they spent their time during a 24-hour period between 04:00 on the previous day and 04:00 on the interview day.

Results: Adjusted multiple linear regression models showed that the largest reciprocal relationship to sleep was found for work time, followed by travel time, which included commute time. Only shorter than average sleepers (<7.5 h) spent more time socializing, relaxing, and engaging in leisure activities, while both short (<5.5 h) and long sleepers (≥8.5 h) watched more TV than the average sleeper. The extent to which sleep time was exchanged for waking activities was also shown to depend on age and gender. Sleep time was minimal while work time was maximal in the age group 45-54 yr, and sleep time increased both with lower and higher age.

Conclusions: Work time, travel time, and time for socializing, relaxing, and leisure are the primary activities reciprocally related to sleep time among Americans. These activities may be confounding the frequently observed association between short and long sleep on one hand and morbidity and mortality on the other hand and should be controlled for in future studies.

Influence of Emotional Expression on Memory Recognition Bias

Influence of Emotional Expression on Memory Recognition Bias: A Functional Magnetic
Resonance Imaging Study
Karine Sergerie, Martin Lepage, and Jorge L. Armony
Biol Psychiatry. 2007 May 31

Background: Most studies of the influence of emotion on memory performance have focused on accuracy. However, there is evidence that emotion can influence other aspects of memory, in particular response bias (overall tendency to classify items as new or old regardless of the accuracy of the response). Here, they investigate the behavioral and neural-related modulation of response bias by emotion.

Methods: Nineteen healthy individuals performed a recognition memory task on faces with happy, sad, and neutral expressions while undergoing functional magnetic resonance imaging (fMRI).

Results: A familiarity (tendency to say “old”) and novelty (tendency to say “new”) bias for sad and happy faces, respectively. Novelty response bias was associated with amygdala and prefrontal cortex activity, whereas familiarity bias correlated with superior temporal gyrus activation.

Conclusions: The results show that emotional expressions can have an influence on memory beyond simple accuracy and that this effect is in part mediated by the amygdala, a region previously implicated in emotional perception and memory. Important clinical relevance since it explains some of the inconsistencies in the literature regarding emotional memory deficits in psychiatric populations.

Unconscious Emotion

Unconscious Emotion
Piotr Winkielman and Kent C. Berridge
University of California, San Diego, and University of Michigan
Current Directions in Psych Science

Conscious feelings have traditionally been viewed as
a central and necessary ingredient of emotion. Here we argue
that emotion also can be genuinely unconscious. We describe
evidence that positive and negative reactions can be elicited
subliminally and remain inaccessible to introspection. Despite
the absence of subjective feelings in such cases, subliminally
induced affective reactions still influence people’s preference
judgments and even the amount of beverage they consume. This
evidence is consistent with evolutionary considerations suggesting
that systems underlying basic affective reactions originated
prior to systems for conscious awareness. The idea of
unconscious emotion is also supported by evidence from affective
neuroscience indicating that subcortical brain systems underlie
basic ‘‘liking’’ reactions. More research is needed to clarify the
relations and differences between conscious and unconscious
emotion, and their underlying mechanisms. However, even under
the current state of knowledge, it appears that processes
underlying conscious feelings can become decoupled from processes
underlying emotional reactions, resulting in genuinely
unconscious emotion.

Facial Expressions of Emotion Influence Memory

Facial Expressions of Emotion Influence Memory for Facial Identity in an Automatic Way
Arnaud D’Argembeau
University of Liege, Belgium
Martial Van der Linden
University of Geneva, Switzerland, and University of Liege, Belgium
Emotion. 2007 Aug;7(3):507-15.

Background: Previous studies indicate that the encoding of new facial identities in memory is influenced by the type of expression displayed by the faces. In the current study, the authors investigated whether or not this influence requires attention to be explicitly directed toward the affective meaning of facial expressions.

Methods: The experiment consisted of a 3 (encoding condition: expression, intelligence,nose size) x 2 (facial expression: happy, angry) mixed model design with encoding condition as a between-participants factor and expression as a within-participants factor.

Results: In a first experiment, the authors found that facial identity was better recognized when the faces were initially encountered with a happy rather than an angry expression, even when attention was oriented toward facial features other than expression. Using the Remember/Know/Guess paradigm in a second experiment, the authors found that the influence of facial expressions on the conscious recollection of facial identity was even more pronounced when participants' attention was not directed toward expressions.

Conclusions: It is suggested that the affective meaning of facial expressions automatically modulates the encoding of facial identity in memory.

Emotional faces predominate in binocular rivalry

Here Is Looking at You: Emotional Faces Predominate in Binocular Rivalry
Georg W. Alpers and Antje B. M. Gerdes
University of Wurzburg
Emotion. 2007 Aug;7(3):495-506.

Background: Two incompatible pictures compete for perceptual dominance when they are presented to one eye each. This so-called binocular rivalry results in an alternation of dominant and suppressed percepts. In accordance with current theories of emotion processing, the authors' previous research has suggested that emotionally arousing pictures predominate in this perceptual process.

Methods: Three experiments were run with pictures of emotional facial expressions that are known to induce emotions while being well controlled in terms of physical characteristics. In Experiment 1, photographs of emotional and neutral facial expressions were presented of the same actor to minimize physical differences. In Experiment 2, schematic emotional expressions were presented to further eliminate low-level differences. In Experiment 3, a probe-detection task was conducted to control for possible response-biases.

Results: These data clearly demonstrate that emotional facial expressions predominate over neutral expressions; they are more often the first percept and they are perceived for longer durations. This is not caused by physical stimulus properties or by response-biases.

Conclusions: This novel approach supports that emotionally significant visual stimuli are preferentially perceived.