The brain dictionary

Natural speech reveals the semantic maps that tile human cerebral cortex
Alexander G. Huth, Wendy A. de Heer, Thomas L. Griffiths, Frédéric E. Theunissen & Jack L. Gallant.
Nature 532, 453–458 (28 April 2016)

The meaning of language is represented in regions of the cerebral cortex collectively known as the ‘semantic system’. However, little of the semantic system has been mapped comprehensively, and the semantic selectivity of most regions is unknown. Here we systematically map semantic selectivity across the cortex using voxel-wise modelling of functional MRI (fMRI) data collected while subjects listened to hours of narrative stories. We show that the semantic system is organized into intricate patterns that seem to be consistent across individuals. We then use a novel generative model to create a detailed semantic atlas. Our results suggest that most areas within the semantic system represent information about specific semantic domains, or groups of related concepts, and our atlas shows which domains are represented in each area. This study demonstrates that data-driven methods—commonplace in studies of human neuroanatomy and functional connectivity—provide a powerful and efficient means for mapping functional representations in the brain.

Explore the brain model for yourself here: http://gallantlab.org/huth2016

 

Curiosity changes brain to enhance learning and memory

States of Curiosity Modulate Hippocampus-Dependent Learning via the Dopaminergic Circuit
Matthias J. Gruber, Bernard D. Gelman, Charan Ranganath
Neuron , Volume 84 , Issue 2 , 486 - 496 

People find it easier to learn about topics that interest them, but little is known about the mechanisms by which intrinsic motivational states affect learning. We used functional magnetic resonance imaging to investigate how curiosity (intrinsic motivation to learn) influences memory. In both immediate and one-day-delayed memory tests, participants showed improved memory for information that they were curious about and for incidental material learned during states of high curiosity. Functional magnetic resonance imaging results revealed that activity in the midbrain and the nucleus accumbens was enhanced during states of high curiosity. Importantly, individual variability in curiosity-driven memory benefits for incidental material was supported by anticipatory activity in the midbrain and hippocampus and by functional connectivity between these regions. These findings suggest a link between the mechanisms supporting extrinsic reward motivation and intrinsic curiosity and highlight the importance of stimulating curiosity to create more effective learning experiences.

Sleep deprivation dynamically alters brain connectivity

The brain functional connectome is robustly altered by lack of sleep.
Kaufmann T, Elvsåshagen T, Alnæs D, Zak N, Pedersen P, Norbom LB, Quraishi SH, Tagliazucchi E, Laufs H, Bjørnerud A, Malt UF, Andreassen OA, Roussos E, Duff EP, Smith SM, Groote IR, Westlye LT.
Neuroimage. 2015 Dec 19

Sleep is a universal phenomenon necessary for maintaining homeostasis and function across a range of organs. Lack of sleep has severe health-related consequences affecting whole-body functioning, yet no other organ is as severely affected as the brain. The neurophysiological mechanisms underlying these deficits are poorly understood. Here, we characterize the dynamic changes in brain connectivity profiles inflicted by sleep deprivation and how they deviate from regular daily variability. To this end, we obtained functional magnetic resonance imaging data from 60 young, adult male participants, scanned in the morning and evening of the same day and again the following morning. 41 participants underwent total sleep deprivation before the third scan, whereas the remainder had another night of regular sleep. Sleep deprivation strongly altered the connectivity of several resting-state networks, including dorsal attention, default mode, and hippocampal networks. Multivariate classification based on connectivity profiles predicted deprivation state with high accuracy, corroborating the robustness of the findings on an individual level. Finally, correlation analysis suggested that morning-to-evening connectivity changes were reverted by sleep (control group) - a pattern which did not occur after deprivation. We conclude that both, a day of waking and a night of sleep deprivation dynamically alter the brain functional connectome.

The reason sleep deprivation alters emotional reactivity

Losing Neutrality: The Neural Basis of Impaired Emotional Control without Sleep.
Simon EB, Oren N, Sharon H, Kirschner A, Goldway N, Okon-Singer H, Tauman R, Deweese MM, Keil A, Hendler T.
Journal of Neurosci. 2015 Sep 23;35(38):13194-205. 

Sleep deprivation has been shown recently to alter emotional processing possibly associated with reduced frontal regulation. Such impairments can ultimately fail adaptive attempts to regulate emotional processing (also known as cognitive control of emotion), although this hypothesis has not been examined directly. Therefore, we explored the influence of sleep deprivation on the human brain using two different cognitive-emotional tasks, recorded using fMRI and EEG. Both tasks involved irrelevant emotional and neutral distractors presented during a competing cognitive challenge, thus creating a continuous demand for regulating emotional processing. Results reveal that, although participants showed enhanced limbic and electrophysiological reactions to emotional distractors regardless of their sleep state, they were specifically unable to ignore neutral distracting information after sleep deprivation. As a consequence, sleep deprivation resulted in similar processing of neutral and negative distractors, thus disabling accurate emotional discrimination. As expected, these findings were further associated with a decrease in prefrontal connectivity patterns in both EEG and fMRI signals, reflecting a profound decline in cognitive control of emotion. Notably, such a decline was associated with lower REM sleep amounts, supporting a role for REM sleep in overnight emotional processing. Altogether, our findings suggest that losing sleep alters emotional reactivity by lowering the threshold for emotional activation, leading to a maladaptive loss of emotional neutrality.

Long-term fear memory

Neural pattern similarity predicts long-term fear memory
Renée M Visser, H Steven Scholte, Tinka Beemsterboer & Merel Kindt
Nature Neuroscience (2013) 

Although certain changes in the brain may reflect fear learning, there are no known markers that indicate whether an aversive experience will develop into fear memory. We examined the moment-to-moment dynamics of human fear learning by applying multi-voxel pattern analysis to single-trial blood oxygen level–dependent magnetic resonance imaging data. We found that the long-term behavioral expression of fear memory could be predicted from neural patterns at the time of learning.

Functional Brain Networks Organization

Functional Brain Networks Develop from a "Local to Distributed" Organization
Damien A. Fair, Alexander L. Cohen, Jonathan D. Power, Nico U. F. Dosenbach, Jessica A. Church,Francis M. Miezin, Bradley L. Schlaggar, Steven E. Petersen
PLoS Computational Biology | 1 May 2009 | Volume 5 | Issue 5 | e1000381

The mature human brain is organized into a collection of specialized functional networks that flexibly interact to support various cognitive functions. Studies of development often attempt to identify the organizing principles that guide the maturation of these functional networks. In this report, we combine resting state functional connectivity MRI (rs-fcMRI), graph analysis, community detection, and spring-embedding visualization techniques to analyze four separate networks defined in earlier studies. As we have previously reported, we find, across development, a trend toward ‘segregation’ (a general decrease in correlation strength) between regions close in anatomical space and ‘integration’ (an increased correlation strength) between selected regions distant in space. The generalization of these earlier trends across multiple networks suggests that this is a general developmental principle for changes in functional connectivity that would extend to large-scale graph theoretic analyses of large-scale brain networks. Communities in children are predominantly arranged by anatomical proximity, while communities in adults predominantly reflect functional relationships, as defined from adult fMRI studies. In sum, over development, the organization of multiple functional networks shifts from a local anatomical emphasis in children to a more "distributed" architecture in young adults. We argue that this "local to distributed" developmental characterization has important implications for understanding the development of neural systems underlying cognition. Further, graph metrics (e.g., clustering coefficients and average path lengths) are similar in child and adult graphs, with both showing "small-world"-like properties, while community detection by modularity optimization reveals stable communities within the graphs that are clearly different between young children and young adults. These observations suggest that early school age children and adults both have relatively efficient systems that may solve similar information processing problems in divergent ways.

How Technology May Soon "Read" Your Mind

Neuroscience has learned so much about how we think and the brain activity linked to certain thoughts that it is now possible - on a very basic scale - to read a person's mind.

Watch this CBS 60 Minutes video to learn more about how this incredible research lets scientists get a glimpse at your thoughts.

Lessons from fMRI Studies of Emotion, Personality, and Social Cognition

Perspectives on Psychological Science a Journal of the Association for Psychological Science had these recent articles. Posted below are the links to the excellent debate/discussions about fMRI statistical analyses and interesting issues for scientific psychology.


Editor's Introduction to Vul et al. (2009) and Comments
Ed Diener

Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social CognitionEdward Vul, Christine Harris, Piotr Winkielman, and Harold Pashler

Commentary on Vul et al.'s (2009) "Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social Cognition"Thomas E. Nichols and Jean-Baptist Poline

Big Correlations in Little Studies: Inflated fMRI Correlations Reflect Low Statistical Power--Commentary on Vul et al. (2009)
Tal Yarkoni

Correlations in Social Neuroscience Aren't Voodoo: Commentary on Vul et al. (2009)
Matthew D. Lieberman, Elliot T. Berkman, and Tor D. Wager

Discussion of "Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social Cognition" by Vul et al. (2009)
Nicole A. Lazar

Correlations and Multiple Comparisons in Functional Imaging: A Statistical Perspective (Commentary on Vul et al., 2009Martin A. Lindquist and Andrew Gelman

Understanding the Mind by Measuring the Brain: Lessons From Measuring Behavior (Commentary on Vul et al., 2009)
Lisa Feldman Barrett

Reply to Comments on "Puzzlingly High Correlations in fMRI Studies of Emotion, Personality, and Social Cognition"
Edward Vul, Christine Harris, Piotr Winkielman, and Harold Pashler

Early Birds and Night Owls

Homeostatic Sleep Pressure and Responses to Sustained Attention in the Suprachiasmatic Area
Christina Schmidt, Fabienne Collette, Yves Leclercq, Virginie Sterpenich, Gilles Vandewalle, Pierre Berthomier, Christian Berthomier, Christophe Phillips, Gilberte Tinguely, Annabelle Darsaud, Steffen Gais, Manuel Schabus, Martin Desseilles, Thien Thanh Dang-Vu, Eric Salmon, Evelyne Balteau, Christian Degueldre, André Luxen, Pierre Maquet, Christian Cajochen, and Philippe Peigneux

Science 24 April 2009 324: 516-519 [DOI: 10.1126/science.1167337] (in Reports)

Throughout the day, cognitive performance is under the combined influence of circadian processes and homeostatic sleep pressure. Some people perform best in the morning, whereas others are more alert in the evening. These chronotypes provide a unique way to study the effects of sleep wake regulation on the cerebral mechanisms supporting cognition. Using functional magnetic resonance imaging in extreme chronotypes, we found that maintaining attention in the evening was associated with higher activity in evening than morning chronotypes in a region of the locus coeruleus and in a suprachiasmatic area (SCA) including the circadian master clock. Activity in the SCA decreased with increasing homeostatic sleep pressure. This result shows the direct influence of the homeostatic and circadian interaction on the neural activity underpinning human behavior.

Spatial and contextual memories

Sleep modulates the neural substrates of both spatial and contextual memory consolidation.
Geraldine Rauchs, Pierre Orban, Christina Schmidt, Genevieve Albouy, Evelyne Balteau, Christian Degueldre, Caroline Schnackers, Virginie Sterpenich, Gilberte Tinguely, Andre Luxen, Pierre Maquet, Philippe Peigneux
PLoS ONE 2008;3(8):e2949.

Background: It is known that sleep reshapes the neural representations that subtend the memories acquired while navigating in a virtual environment. However, navigation is not process-pure, as manifold learning components contribute to performance, notably the spatial and contextual memory constituents. In this context, it remains unclear whether post-training sleep globally promotes consolidation of all of the memory components embedded in virtual navigation, or rather favors the development of specific representations.

Methods: Here, we investigated the effect of post-training sleep on the neural substrates of the consolidation of spatial and contextual memories acquired while navigating in a complex 3D, naturalistic virtual town. Using fMRI, we mapped regional cerebral activity during various tasks designed to tap either the spatial or the contextual memory component, or both, 72 h after encoding with or without sleep deprivation during the first post-training night.

Results: Behavioral performance was not dependent upon post-training sleep deprivation, neither in a natural setting that engages both spatial and contextual memory processes nor when looking more specifically at each of these memory
representations. At the neuronal level however, analyses that focused on contextual memory revealed distinct correlations between performance and neuronal activity in frontal areas associated with recollection processes after post-training sleep,
and in the parahippocampal gyrus associated with familiarity processes in sleep-deprived participants. Likewise, efficient spatial memory was associated with posterior cortical activity after sleep whereas it correlated with parahippocampal/
medial temporal activity after sleep deprivation. Finally, variations in place-finding efficiency in a natural setting encompassing spatial and contextual elements were associated with caudate activity after post-training sleep, suggesting
the automation of navigation.

Conclusion: These data indicate that post-training sleep modulates the neural substrates of the consolidation of both the spatial and contextual memories acquired during virtual navigation.

Emotional Context

Decoding of affective facial expressions in the context of emotional situations
Monika Sommera, Katrin Döhnela, Jörg Meinhardtb and Göran Hajaka
Neuropsychologia Volume 46, Issue 11, September 2008, Pages 2615-2621

Background: The ability to recognize other persons’ affective states and to link these with aspects of the current situation arises early in development and is precursor functions of a Theory of Mind (ToM). Until now, studies investigated either the processing of affective faces or affective pictures.

Methods: In the present study, we tried to realize a scenario more similar to every day situations. We employed fMRI and used a picture matching task to explore the neural correlates associated with the integration and decoding of facial affective expressions in the context of affective situations. In the emotion condition, the participants judged an emotional facial expression with respect to the content of an emotional picture. In the two other conditions, participants indicated colour matches on the background of either affective or scrambled pictures.

Results: In contrast to colour matching on scrambled pictures, colour matching on emotional pictures resulted in longer reaction times and increased activation of the bilateral fusiform and occipital gyrus. These results indicated that, although task irrelevant, participants may attend to the emotional background of the pictures. The emotion task was associated with higher reaction times and with activation of the bilateral fusiform and occipital gyrus. Additionally, emotion attribution induced left amygdala activity. Possibly, attention processes and amygdala projections modulated the activation found in the occipital and fusiform areas. Furthermore, the involvement of the amygdala in the ToM precursor ability to link facial expressions with an emotional situation may indicate that the amygdala is involved in the development of stable ToM abilities.

How Sleep affects Memory and Congition

Functional neuroimaging insights into how sleep and sleep deprivation affect memory and cognition.
Chee Michael WL and Chuah Lisa YM b
Current Opinion in Neurology. 24(4):417-423, August 2008.

Purpose of review: The review summarizes current knowledge about what fMRI has revealed regarding the neurobehavioral correlates of sleep deprivation and sleep-dependent memory consolidation.

Recent findings: Functional imaging studies of sleep deprivation have characterized its effects on a number of cognitive domains, the best studied of these being working memory. There is a growing appreciation that it is important to consider inter individual differences in vulnerability to sleep deprivation, task and task difficulty when interpreting imaging results. Our understanding of the role of sleep and the dynamic evolution of offline memory consolidation has benefited greatly from human imaging studies. Both hippocampal-dependent and hippocampal-independent memory systems have been studied.

Summary: Functional imaging studies contrasting sleep-deprived and well-rested brains provide substantial evidence that sleep is highly important for optimal cognitive function and learning. The experimental paradigms developed to date merit evaluation in clinical settings to determine the impact of sleep disruption in sleep disorders.

Persistence of Emotional Memories Over Time

Role of Amygdala Connectivity in the Persistence of Emotional Memories Over Time: An Event-Related fMRI Investigation
Maureen Ritchey, Florin Dolcos and Roberto Cabeza
Cerebral Cortex, 2008

Background: According to the consolidation hypothesis, enhanced memory for emotional information reflects the modulatory effect of the amygdala on the medial temporal lobe (MTL) memory system during consolidation. Although there is evidence that amygdala--MTL connectivity enhances memory for emotional stimuli, it remains unclear whether this enhancement increases over time, as consolidation processes
unfold.

Methods: They used functional magnetic resonance imaging to measure encoding activity predicting memory for emotionally negative and neutral pictures after short (20-min) versus long (1-week) delays.

Results: Memory measures distinguished between vivid remembering (recollection) and feelings of knowing (familiarity). Consistent with the consolidation hypothesis, the persistence of recollection over time (long divided by short) was greater for emotional than neutral pictures. Activity in the amygdala predicted subsequent memory to a greater extent for emotional than neutral pictures. Although this advantage did not vary with delay, the contribution of amygdala--MTL connectivity to subsequent memory for emotional items increased over time. Moreover, both this increase in connectivity and amygdala activity itself were correlated with individual differences in recollection persistence for emotional but not neutral pictures.

Conclusion: These results suggest that the amygdala and its connectivity with the MTL are critical to sustaining emotional memories over time, consistent with the consolidation hypothesis.

Looking inside the brain in real time

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.