Obesity: Reviving the Promise of Leptin

Hi everyone,

Here's the link to my article: Obesity: Reviving the Promise of Leptin

Musical Behavior in a Neurogenetic Developmental Disorder

Here is the link to the article by Daniel J. Levitin:

http://ego.psych.mcgill.ca/labs/levitin/research/MusicalBehaviorNeuro.pdf

And here is a link to a NYtimes article which explains Williams syndrome:

http://www.nytimes.com/2007/07/08/magazine/08sociability-t.html

Medial Prefrontal Cortex Links Music, Memory, and Emotion

In a study at UC Davis, Petr Janata mapped the areas of the brain that responded to clips of familiar music, to explore the locations that play a role in the integration of music and autobiographical memories. The area he established as the “hub” that links familiar music, memories, and emotions is the medial prefrontal cortex (MPFC), already understood to be where memories are “supported and retrieved.”

Janata based his hypothesis that the MPFC would be at the center of activity on several previous studies that showed it to be involved in autobiographical memory retrieval. In several of his own earlier studies, Janata had observed that the MPFC is used to track music through tonal space, and that music serves as a powerful retrieval cue for autobiographical memories. Another compelling study showed that the MPFC atrophies more slowly than other brain areas in patients with Alzheimer’s disease, and that memory for familiar music is something that these patients retain longer than many other memories.



There were two hypotheses being tested in this experiment: the first is that activity in the MPFC would show positive correlation to the familiarity, autobiographical salience, and positive affect brought about by the music. The second was that overlapping areas, of those in close proximity to those demonstrating positive correlation, would track the musical excerpts through tonal space. For the sake of time, I will address the first hypothesis.

Method:
Janata’s study involved 13 students at UC Davis. Using songs from the Top 100 charts from when the subjects were between 7 and 19 (to ensure there would be some familiarity with the songs), Janata used fMRI scans to monitor their brains while they listened to 30 second excerpts from 30 different songs.

Following each excerpt, subjects pressed buttons on a keypad to respond to questions about the valence (how pleasant the music was) and arousal while listening to the clip, their familiarity with the song, whether it held any particular autobiographical associations for them, the orientation of their attention to those associations/memories, and the orientation of their attention to the music itself. After the fMRI monitoring, subjects completed a survey about the memories they had experienced while listening to the song excerpts.

Results:
From the 17 songs that the subjects remembered on average, 13 had moderate to strong associations to autobiographical memories. Songs that had the strongest associations also evoked the most emotional, vivid responses. In the fMRI images, these memories corresponded to activity in the upper part of the MPFC.


This shows the results of the ratings the subjects assigned to each song excerpt. Black represents the most negative value for each scale, and white represents the most positive.




Abbreviations: STG, superior temporal gyrus; DLPFC, dorsolateral prefrontal cortex; DMPFC, dorsomedial prefrontal cortex; VLPFC, ventrolateral prefrontal cortex; VMPFC, ventromedial prefrontal cortex; IFG, inferior frontal gyrus; FO, frontal operculum; IPS, intraparietal sulcus; AG, angular gyrus; pSMA, presupplementary motor area; ACC, anterior cingulate cortex; PCC, posterior cingulate cortex; IFS, inferior frontal sulcus; MFG, middle frontal gyrus; Ins, insula; SPL, superior parietal lobule; Cb, cerebellum; PT, planum temporale; vltn, ventral lateral thalamic nucleus; and MTG, middle temporal gyrus.

In these images, you can see brain activity during different phases of the experiment: music playing, question-answer period, and the effects of familiarity, autobiographical salience, and valence. FAV represents “the combined effects of hearing pleasing, familiar, and autobiographically salient songs relative to unfamiliar, emotionally neutral, or displeasing songs that elicited no autobiographical association.” These images show the concentration of activity related to associations in the prefrontal cortex, as well as the left-hemispheric bias (the negative numbers refer to the left hemisphere).




In this second set of images, you can see the individual effects of familiarity, autobiographical salience, and valence, showing the same trends as the first set of images.


Implications:
Janata’s results show that the MPFC is key in associating familiar music with autobiographical memories. Importantly, it links structural characteristics of a retrieval cue with episodic memories (in spontaneous, rather than effortful, retrieval). This builds on existing knowledge of autobiographical memory by demonstrating the “spontaneous activation of an autobiographical memory network in a naturalistic task with low retrieval demands.”

Although Janata’s study itself did not suggest the uses or applications of this discovery, he is quoted in the ScienceDaily article as saying that a long-term goal for this new knowledge was to use music to improve Alzheimer’s patients’ quality of life.



Sources:
Janata, P. (2009). The Neural Architecture of Music-Evoked Autobiographical Memories. Retrieved February 24, 2009, from Cerebral Cortex Website: http://cercor.oxfordjournals.org/cgi/content/full/bhp008v1#ABS

Nervous System. Retreived March 1, 2009, from A Review of the Universe Web site: http://universe-review.ca/R10-16-ANS.htm

University of California - Davis (2009, February 24). Brain Hub That Links Music, Memory And Emotion Discovered. Retrieved February 24, 2009, from Science Daily Web site: http://www.sciencedaily.com/releases/2009/02/090223221230.htm

Imaging Study on Women with Anorexia Nervosa

"Sense of Taste Different
in Women with Anorexia Nervosa" 
Imaging Study Finds Brain Changes Associated with the Regulation of Appetite .
September 25, 2007
By Debra Kain

Although anorexia nervosa is categorized as an eating disorder, it is not known whether there are alterations of the portions of the brain that regulate appetite. Now, a new study finds that women with anorexia have distinct differences in the insula – the specific part of the brain that is important for recognizing taste – according to a new study by University of Pittsburgh and University of California, San Diego researchers currently on line in advance of publication in the journal Neuropsychopharmacology. The study also implies that there may be differences in the processing of information related to self-awareness in recovering anorexics compared to those without the illness – findings that may lead to a better understanding of the cause of this serious and sometimes fatal mental disorder. In the study led by Angela Wagner, M.D., University of Pittsburgh School of Medicine, and Walter H. Kaye, M.D., of the University of Pittsburgh and the University of California, San Diego (UCSD) Schools of Medicine, the brain activity of 32 women was measured using functional magnetic resonance imaging (fMRI.) The research team looked at images of the brains of 16 women who had recovered from anorexia nervosa – some of whom had been treated at the Center for Overcoming Problem Eating at Western Psychiatric Institute and Clinic of the University of Pittsburgh Medical Center –and 16 control subjects. They measured their brains’ reactions to pleasant taste (sucrose) and neutral taste (distilled water.)
The results of the fMRI study are the first evidence that individuals with anorexia process taste in a different way than those without the eating disorder. In response to both the sucrose and water, imaging results showed that women who had recovered from anorexia had significantly reduced response in the insula and related brain regions when compared to the control group. These areas of the brain recognize taste and judge how rewarding that taste is to the person. In addition, while the controls showed a strong relationship between how they judged the pleasantness of the taste and the activity of the insula, this relationship was not seen in those who had recovered from anorexia. According to Kaye, it is possible that individuals with anorexia have difficulty recognizing taste, or responding to the pleasure associated with food. Because this region of the brain also contributes to emotional regulation, it may be that food is aversive, rather than rewarding. This could shed light on why individuals with anorexia avoid normally “pleasurable” foods, fail to appropriately respond to hunger and are able to lose so much weight. “We know that the insula and the connected regions are thought to play an important role in interoceptive information, which determines how the individual senses the physiological condition of the entire body,” said Kaye. “Interoception has long been thought to be critical for self-awareness because it provides the link between thinking and mood, and the current body state.” This lack of interoceptive awareness may contribute to other symptoms of anorexia nervosa such as distorted body image, lack of recognition of the symptoms of malnutrition and diminished motivation to change, according to Kaye. Anorexia nervosa is a serious and potentially lethal illness, which may result in death in ten percent of cases. Anorexia commonly begins during adolescence, but strikes throughout the lifespan, and is nine times more common in females than in males. These characteristics support the possibility that biological processes contribute to developing this disorder.


Why does this study hold significance?

Anorexia Nervosa is a disorder of unknown etiology. The stigma that has lastingly attached itself to the disease supports that psychological reasons are responsible for the birth of the disorder. Despite this, it is being questioned whether individuals afflicted with anorexia, have a primary disturbance of pathways that modulate feeding, or if disturbed appetite is secondary to psychological elements of the disease such as anxiety, and an obsession with weight gain. Through this case study, we are able to see that the controlled women acknowledged a pleasant relationship with the ingestion of sucrose and their signal activity supported that as well. Conversely, the recovered anorexics of this study possessed no relationship between the pleasantness of sugar’s taste and any brain region. Both groups showed no anxiety or pleasantness of the taste of water in relation to any brain region. These results support the hypothesis that recovered anorexics have disturbances in their taste processing via the central nervous system. We see that the insula can assert the value of taste stimuli and consequently influence how that stimuli affect’s the state of the human body. If an anorexic cannot distinguish her feelings towards particular foods—if she experiences no neurological reward or taste value—it is easier for her to fall into disordered eating habits, especially if she has psychological instabilities that would only strengthen her resistance to food. Essentially, this study was the first of its kind in showing that there is a disturbance in the insula and other primary taste regions of the brain in anorexics, which in turn can help professionals potentially treat Anorexia Nervosa in a more inclusive way.

http://www.nytimes.com/2007/02/06/health/psychology/06brain.html

The link above has a more specified article on the insula, and an interesting diagram to match, if anyone wants more background information on the insula.

Other Sources:

www.neuropyschopharmacology.org
"The Mind Has a Body of its Own," by Sandra and Matthew Blakeslee.

Oxytocin and Generosity

The Study:

The study attempted to connect the neuromodulator oxytocin with increased generosity by showing that it increases perspective-taking or empathy.

To isolate oxytocin’s impact on perspective-taking, the researchers used two money transfer tasks, the Ultimatum Game and the Dictator Game

In both tasks, participants were randomly assigned to pairs, but did not have the opportunity to see or converse with their partners. One member of the pair (referred to as Decision Maker 1, in the study, but referred to here as the Giver) was given $10. The other member of the pair (referred to in the study as Decision Maker 2, but referred to here as the Receiver) received no money at the start of the game.

Ultimatum Game: In the Ultimatum Game, the Giver was asked to choose an amount of money to transfer to the Receiver. If the Receiver accepted the transfer, both partners got the agreed-upon amounts of money. If, on the other hand, the Receiver rejected the offer as too stingy, neither partner kept any money. The Giver only had the opportunity to make one offer and could not renegotiate.

Dictator Game: In the Dictator Game, the Receiver had to accept whatever amount of money was given to him by the Giver.

The Ultimatum Game differs from the Dictator Game in that, in order to succeed at the task, the Giver must think about what the Receiver will do. The researchers encouraged this by asking all participants, before they were assigned to particular roles, to think about both the amount they would transfer as a Giver and the minimum amount they would accept as a Receiver. In the Dictator Game, the Giver does not need to explicitly think about the Receiver, but instead “simply decides how much one would like to give up.”

Before completing these tasks, half of the participants were infused intranasally with oxytocin and the other half were given an intranasal placebo to see what effect oxytocin would have on decision-making in the two games.

The Results:

As the researchers predicted, oxytocin increased the magnitude of transfers in the Ultimatum Game, but not in the Dictator Game. Only when participants had to think about another person did oxytocin affect they amount they were willing to give. Participants who had received oxytocin gave 21% more as Givers in the Ultimatum Game than those who had received the placebo.

The average transfers in the Ultimatum Game were $4.86 for the oxytocin group and $4.03 for the control group.

The researchers distinguished between generosity and altruism.

Generosity: Liberality in giving. Offering more to another than he or she expects.
Altruism: Helping another at a cost to oneself.

The Ultimatum Game most nearly tests generosity, since it compares the amounts a person is willing to give to an amount that is expected, while the Dictator Game most nearly tests altruism, since it measures how much of a cost to oneself one is willing to endure, without any particular mark of comparison.

In the Ultimatum Game, significant generosity is shown by participants who have taken oxytocin, meaning that these participants gave more than the average amount that people would be willing to accept as a Receiver. Those who had taken oxytocin were 80% more generous.


From this, the researchers concluded that oxcytocin increases generosity, but not altruism, by increasing participants’ ability to take on the perspective of another person. The researchers hypothesized that when participants in the oxytocin group thought about the Receiver while acting as Giver in the Ultimatum Game, they identified more strongly with the disappointment and negative emotions that the Reciever would feel if the transfer was small, and so they gave larger amounts. The paper states, “OT [oxytocin] appeared to have selectively affected the understanding of how another would experience a negative emotion, and seemed to have motivated a desire to reduce DM2s’ [Receivers’] experienced negativity. This could be called empathy.”

An Alternative Reading of the Data:

Another explanation for the effects of oxytocin in the Ultimatum Game could be that oxytocin decreases risk-taking behavior. Givers who have received oxytocin might give more because they prefer to secure a smaller amount for themselves than to risk having their offer rejected and getting nothing. This explanation is not likely, however, because oxytocin did not have any effect on the minimum offer that participants were willing to accept as Receiver. If oxytocin led to risk-aversion, Receivers would also be willing to accept smaller, secure amounts, rather than sticking to a higher acceptance threshold. Also, another experiment, primarily designed to study the effects of oxytocin on trust levels, showed that oxytocin does not affect risk-taking.

Calling Out Discover:

The end of the Discover article raises the spectre of casinos filling the air with oxytocin to make people gamble more. As I just stated, the actual study suggests no link between oxytocin and risk-taking. The increased payouts in the study occurred only when participants were induced to actively think about the person who would benefit from their giving. This would be helpful to casinos only if people pulling the slot machine considered how the casino owner would feel about receiving their money—an unlikely scenario. The Discover comment is purely sensationalist.

What is Oxytocin Anyhow?

Oxytocin is a neuromodulator which is primarily known for its involvement in female reproduction. It is critical to birth and breastfeeding. Recent research has discovered that it is also very important in regulating social interactions. One study showed that mice with a mutant gene that prevented them developing oxytocin receptors lacked social memory. The connection between oxytocin and sociality is supported by the fact that areas of the brain that deal with emotions and social behavior tend to have more oxytocin receptors. These areas include the amygdala, hypothalamus, and anterior cingulate.

fMRI Evidence:

In a recent study, participants decided whether or not to make donations to social causes while undergoing an fMRI. The study found that, when participants chose to make donations, the mesolimbic-striatal reward system was activated in the same way as when participants were given monetary rewards. This accounts in part for the positive feelings associated with giving. In addition, participants making donations showed activation in the subgenual area (including Brodmann’s area 25) which was not activated while receiving money. This area is important in social attachment and affiliation. It is also involved in the release of oxytocin, suggesting that oxytocin has an effect on making decisions about donations. This reinforces the link between oxytocin and generosity.


(a) Mesolimbic–striatal reward system, including the VTA and the dorsal and ventral sectors of the striatum (STR), activation for both pure monetary reward and noncostly donation (conjunction of pure reward vs. baseline and noncostly donation vs. baseline). (b) Subgenual area (SG) activation for decisions to donate (conjunction of costly and noncostly conditions) as compared with pure monetary reward. The subgenual area comprised the most posterior sector of the medial orbitofrontal cortex and the ventral cingulate cortex (BA 25) and the adjoining septal region structures. (Caption taken from Moll, J., et. al.)


Area 25 was activated during the donation task, and is involved in the release of oxytocin.

Another study examined the effects of oxytocin on the amygdala. Participants were given either oxytocin or a placebo intranasally. Then, while undergoing an fMRI scan, they viewed angry and fearful faces and threatening scenes. For those who had received the placebo, this caused a large amount of activation in the amygdala. Those who had received oxytocin showed significantly less activation in the amygdala, suggesting that oxytocin can interfere with fear responses. The authors of “Oxytocin Increases Generosity in Humans” suggest that interference with the amygdala by oxytocin may make people less anxious about resource scarcity, and therefore more likely to give larger amounts in the Ultimatum Game. Another study has shown that oxytocin increases people’s willingness to trust strangers. This effect could be attributed to decreased activity in the amygdala inhibiting normal fear of betrayal.

Significance:

As the role of oxytocin in regulating social behavior comes to be better understood, it could be involved in new treatments of social disorders. The connection between oxytocin and perspective-taking indicated by this study may be of particular importance to autism researchers.

Sources:

Barone, J (2008) Can the hormone oxytocin drive us to be more generous? Discover. Retreived February 21, 2009, from http://discovermagazine.com/2008/apr/04-a-dose-of-human-kindness-now-in-chemical-form

Ferguson JN, Young LJ, Hearn EF, Matzuk MM, Insel TR, Winslow JT (2000) Social amnesia in mice lacking the oxytocin gene. Nat Genet 25: 284–298.
Kosfeld M, Heinrichs M, Zak PJ, Fischbacher U, Fehr E (2005) Oxytocin increases trust in humans. Nature 435: 673–676.

Moll J, Krueger F, Zahn R, Pardini M, de Oliveira-Souza R, Grafman J (2006) Human fronto–mesolimbic networks guide decisions about charitable donation. Proc Nat Acad Sci 103: 15623–15628.

National Institute of Mental Health (2005) Trust-building hormone short-circuits fear in humans. Retrieved February 21, 2009, from http://www.nih.gov/news/pr/dec2005/nimh-07.htm

Zak PJ, Stanton AA, Ahmadi S (2007) Oxytocin Increases Generosity in Humans. PLoS ONE 2(11): e1128. doi:10.1371/journal.pone.0001128

Just a test post!

Music, Memory, and Emotion

Here is my article from ScienceDaily:

Brain Hub That Links Music, Memory And Emotion Discovered

Enjoy!