Existential Neuroscience

Is it reasonable to fear death? If you agree with Lucretius, you will say no. In what is known as the Symmetry Argument, Lucretius contends that that the time before our existence is similar to the time of our future non-existence. And since we do not fear the time before we existed, it is not reasonable to fear our future non-existence i.e. death. (See Rosenbaum, 1989 for a more detailed exposition)

However, even if you concede to Lucretius’s argument, the fact remains that the awareness of our mortality generates a significant threat to our psychological well-being. A large corpus of research on terror management theory details how mortality saliency affects our self-esteem, worldview, among others.

In a recent fMRI study, Quilin and colleagues (2011) extends our knowledge on terror management theory by exploring the neural correlates of mortality salience. They were interested in the activity of the amygdala, rostral anterior cingulated gyrus (ACC), ventral tegmental & caudate nucleus (CN).

In this within-subjects experiment, thoughts of death were induced in the participants by requiring them to agree or disagree with a statement such as I am afraid of a painful death. Statements about dental pain were used in the control condition.

Results

The authors found higher activations in:

• Right amygdala
• Left ACC
• Right CN

They suggested that the activations in the amygdala and ACC may indicate ‘non-conscious, latent markers of threat aroused by mortality salience’ and that further investigations may reveal the role of the CN in regards to the defensive mechanisms that we employ against mortality threat.

This area seems promising to me and more research needs to be done to help us better understand how we deal with threats of mortality. It would also be interesting to look at how religious affiliations affect the way the brain deal with existential fears. If indeed 'mortality threats functions as a potential for anxiety rather than as experienced anxiety', what can neuroimaging techniques tell us about whether believing in a higher being help us deal with the potential or experienced anxiety resulting from mortality threats?



Quirin M, Loktyushin A, Arndt J, Küstermann E, Lo YY, Kuhl J, & Eggert L (2011). Existential neuroscience: a functional magnetic resonance imaging investigation of neural responses to reminders of one's mortality. Social cognitive and affective neuroscience PMID: 21266462

Rosenbaum, S. (1989). The Symmetry Argument: Lucretius Against the Fear of Death Philosophy and Phenomenological Research, 50 (2) DOI: 10.2307/2107964

Beauty-is-Good Stereotype in the Brain

Leo Tolstoy once said, “It is amazing how complete is the delusion that beauty is goodness.” And how complete is this delusion? In a recent study, Tsukiura & Cabeza (2011) provides an insight into this question by investigating the neural mechanism underlying the Beauty-is-Good stereotype. They were interested in the activity of the medial orbito frontal cortex (associated with positive stimuli, reward processing etc); the insular cortex (associated with negative stimuli, punishment processing etc) and the interaction between these two regions.

This fMRI study required participants to engage in 3 different tasks:

1. Face attractiveness rating (beauty judgment task)
2. Action goodness rating (moral judgment task)
3. Brightness rating (control condition)

The 3 tasks. Click to enlarge

Conforming to their hypothesis, the authors found that activity in the mOFC increased linearly as a function of both attractiveness and goodness rating. Activity in the insular cortex also decreased linearly as a function of both types of ratings. In both regions, the strong correlation between the activations caused by both judgments also supports the idea that similar neural regions are engaged when we are processing attractiveness and moral goodness.

Furthermore, the negative correlation between right mOFC and right insular cortex provides support for the “dual process hypothesis” of the Beauty is Good stereotype in that we display both a positive bias of attractiveness as being good and a negative bias against unattractiveness as being bad.

That is to say, the stereotype is driven by two opposing mechanism whereby we tend to think that an attractive person is more moral and an unattractive person is less moral, rather than a singular bias towards attractiveness or unattractiveness.

Click to enlarge

Our delusion that beauty is goodness then appears to have been built into how our brain processes both type of judgments and the completeness of this delusion may surprise even the great Leo Tolstoy.

Tsukiura T, & Cabeza R (2011). Shared brain activity for aesthetic and moral judgments: implications for the Beauty-is-Good stereotype. Social cognitive and affective neuroscience, 6 (1), 138-48 PMID: 20231177

When it's moving, it's hard to see it changing.

Change blindness is a phenomenon whereby people fail to detect sizable changes in a visual scene. This can occur even when they are actively trying to locate the change (Simons & Ambinder, 2005). If you are unaware of this phenomenon, you can go to UBC's psychology department where they have some interesting video examples.

In a new study, Suchow & Alvarez (2011) demonstrates a novel visual illusion whereby motion induces failure to detect change - or what they call 'silencing'. Look at the video embedded below. Initially, the dots are visibly changing in colour but once the rotation begins, the dots appear to stop changing or at least appear to change at a slower rate. Additional video demonstrations looking at brightness, size and shape can be found here.

Motion silences awareness of color changes from Jordan Suchow on Vimeo.

They found that the faster the rotation, the slower the dots appear to change (i.e. stronger silencing).

Click to enlarge

In an additional set of experiments, they further determined that motion on the retina and not motion in space is responsible for silencing. Pretty nifty visual illusion huh.

*We are glad to have our first post based on a reader article submission and welcome additional submissions. Spread the word!

Suchow JW, & Alvarez GA (2011). Motion Silences Awareness of Visual Change. Current biology : CB PMID: 21215632
Simons, D., & Ambinder, M. (2005). Change Blindness. Theory and Consequences Current Directions in Psychological Science, 14 (1), 44-48 DOI: 10.1111/j.0963-7214.2005.00332.x

Birth Order Influences the Formation of Long-Term Relationships

134 years since Francis Galton opened the birth order effects debate by observing that first-born sons and only sons were over-represented among English scientists, controversy has shrouded the issue such that we haven't quite gotten past whether birth order effects exist or not, let alone properly consider what they are or how they work.

Some scholars assert that the lack of conclusive evidence is due to methodological biases that may allow the researcher to find the result that he or she is looking for. So, in that sense, a researcher who seeks to confirm that the birth order effect exists may find it just as well as a researcher who seeks to disconfirm it might.

In Birth Order Effects in the Formation of Long-Term Relationships, Hartshorne, Salem-Hartshorne and Hartshorne seek to probe the birth effect in a manner that is as methodologically neutral as possible by simply determining if there are any correlations between the sharing of birth order and the likelihood of long-term relationship formation. Their results provide new research material that weighs in favour of the presence of birth order effects, though what drives this effect is still speculative.

By drawing on a sample of 900 US undergraduate students, the researchers found that people are more likely to form and be in long-term relationships, both friendly and romantic, if they share the same birth order than would be expected by chance. For instance, if I were a first-born child, the likelihood of me being close friends with another first-born child is higher than the likelihood of me being close friends with another second- or third-born child. This tendency was also found for romantic partners.

A second and similar web-based study was conducted which gathered responses from American participants (1,911) as well as participants from other parts of the world (713). Similar results were garnered. There was no significant difference detected between American and non-American respondents, suggesting that birth order effects on long-term relationships are not culturally variant.

The researchers also controlled for socioeconomic status and size of family, which is a progressive extension from other earlier studies. This eliminates the confounds of number of siblings one has and the socioeconomic class one belongs to, which can potentially influence one's development because it is a commonly known social phenomenon that wealthier and upper class families tend to have less offspring.

The authors surmise that birth order underlies personality traits and having the same birth order results in greater compatibility between personality types, leading to the formation of closer bonds in both friendships and romantic relationships.

Joshua K. Hartshorne, Nancy Salem-Hartshorne, and Timothy S. Hartshorne (2009). Birth Order Effects in the Formation of Long-Term Relationship Journal of Individual Psychology, 65 (2)

Detecting facial emotions: Women vs Men

Do women really recognize facial emotion better than men? Existing literature on the subject remains contradictory with some studies showing a female advantage (albeit with small effect sizes) and others failing to find any gender differences. Hoffman and colleagues (2010) suggest that expression intensity is an important factor mediating gender differences in recognizing emotions and that while women do recognize facial emotions better than men, this advantage only exists for subtle emotional facial expressions.

Using a facial expression morphing tool (FEMT), they manipulated the intensity of the emotional facial expression for their stimuli. Looking at the 40% intensity, I must say that it is in fact pretty hard for me to identify.

click to enlarge

Conforming to their hypothesis, they found that women indeed only recognize subtle emotional expression better than men but not when full-blown emotions are displayed. Decreased emotional intensity negatively affected the judgments of male participants more than that of female participants.  

But of course accurately detecting facial emotions is just the first part of the equation, whether you deal with it adequately is another thing altogether - especially when they are subtle. 

Hoffmann H, Kessler H, Eppel T, Rukavina S, & Traue HC (2010). Expression intensity, gender and facial emotion recognition: Women recognize only subtle facial emotions better than men. Acta psychologica, 135 (3), 278-83 PMID: 20728864

Early Life Experience and Neurodegeneration

Although some studies have found that early life environmental factors can affect our vulnerability to neurodegenerative diseases such as Alzheimer’s disease in later life, the underlying neuronal mechanisms of such vulnerability are not well understood. By looking at post mortem rhesus monkey brains, Merrill et al. (2011) finds an association between early life experience and subsequent risk of exhibiting neurodegeneration in later life.

In the study, β-amyloid plaque density and synaptophysin immunoreactivity in the brains of the rhesus monkeys that had lived in standard sized cages VS small cages (29% smaller than standard cages) for the first 15 years were compared. Young monkeys were also used as a basis for comparison.

β-amyloid plaque density

β-amyloid deposition has been established as the central cause of Alzheimer’s disease (Hardy & Allsop, 1991). The researchers found that monkeys that were housed in small cages had higher β-amyloid plaque density and amyloid load in the superior temporal gyrus compared to monkeys that were housed in standard sized cages. Young monkeys had no detectable amyloid deposition and were not graphed.

click to enlarge

However, I think the β-amyloid density results should be taken with a pinch of salt. Although the authors did mention that there is considerable individual variation - which parallels data in human studies, the effects seemed to be heavily driven by the monkey which had almost 140 plaques per mm square. Also, there were only 5 monkeys in the small cage condition and 3 of them appear to have comparable β-amyloid density levels. The authors also did not include individual data for the superior temporal gyrus amyloid load graph but the large error bar again suggests significant individual variations.

Synaptophysin Immunoreactivity

Monkeys reared in small cages also showed a reduction in synaptophysin immunoreactivity - a presynaptic marker, in the superior temporal gyrus. This indicates a decrease in synaptic density and activity which has been linked with cognitive impairment in Alzheimer's disease.

All said, the value of the study lies in their finding “early life experience is associated with degenerative change in the non-diseased aged brain” (emphasis theirs). Therefore, even in normal aging, our early life experiences can affect the rate of neural degeneration. Remind me to get a bigger crib for my child in the future.


Merrill DA, Masliah E, Roberts JA, McKay H, Kordower JH, Mufson EJ, & Tuszynski MH (2011). Association of early experience with neurodegeneration in aged primates. Neurobiology of aging, 32 (1), 151-6 PMID: 19321231

Effects of sleep on Remembering to Remember

Prospective memory is a class of memory that is unique in that it involves the future rather than the present or the past. Various examples of prospective memory include remembering to buy a pet monkey, or remembering to break up with your girlfriend or remembering to do that blasted thesis that you have been putting off for the umpteenth time. Hence, some researchers have called it the act of "remembering to remember" (Winograd, 1988). Although prospective memory is quite important for daily functioning and goal fulfilment, research on it has been quite sparse in comparison to other forms of memory. One big question remains: how do we remember to remember? Do we devote some resources to maintain this intention? Or is it maintained without anything being devoted to it?

You know you want it.

One theory of prospective memory suggests that prospective memory can be both effortful and automatic. One way in which prospective memory can be automatic is when cues in our environment alert us to something we have to do. Kvavilashvili and Fisher (2007) has found that individuals often encounter cues related to a goal (eg, seeing a monkey in the magazine, receiving a text message from the girlfriend) and these cues spontaneously remind participants of their goal. Another way in which prospective memory is maintained is through conscious retrieval. Other researchers have also found that prospective memory surprisingly is better after 15 minutes than 3 minutes, one interpretation being that participants consciously retrieve and rehearse the goal prior to and up to the point when they are going to execute it (Hicks, Marsh & Cook, 2005).

One question that arises from these findings is that, what happens when we sleep on something? During sleep it appears that both automatic and effortful mechanisms are absent; we don't consciously retrieve and rehearse goals, and we aren't exposed to cues from the external environment. In such a case we might expect that prospective memory would weaken. However, given that a huge amount of literature has also shown that sleep improves memory, we might expect that sleep would improve prospective memory. These contradictory hypotheses form the basis for Scullin and McDaniel's study, "Remembering to execute a Goal: Sleep on it!" (2010)

The researchers had participants do a series of tasks (too lengthy to cover), while remembering to do a particular action at a particular time ("press the Q key when you see the word table or horse"). In one set of participants, this target came after a short delay (20 minutes) while in the long delay condition, participants were told to come back after 12 hours for another series of experiments and the target came there. The other crucial manipulation was time of day, the experiment for one set of participants was started in the morning, and the other set at night. The study was between groups, so participants were spread out across 4 conditions.

1. Short Morning Delay

2. Short Evening Delay

3. Wake Delay (from morning to night, during which time the participant was awake)

4. Sleep Delay (from night to morning, during which time the participant was sleeping)

What the researchers found was that sleeping improved the ability to remember to do something, as compared to being awake. In some of the tests, the performance was almost as good as if one was tested after 20 minutes. One important possible confound in this experiment was that the sleep and awake conditions also differed not just in amount of sleep but also when the experiment was conducted. The authors eliminated this confound by comparing performance for prospective memory during the day and night after a short delay and found that time of day had little effect.

So the results are inconsistent with the idea that sleep might undermine prospective memory by preventing conscious retrieval or exposure to environmental stimuli. It seems like prospective memory might not rely heavily on these 2 processes, as suggested by some proponents of the theory above. The implication being that if you need to remember to do something, you might as well sleep on it.

But how does sleep improve prospective memory? The authors suggest that sleep increases associative binding and that it amplifies weak goals or links. In this case, it seems like prospective memory might not be very much different from other types of memory. However the authors find that sleep improves prospective memory for only certain types of tasks, thus raising new avenues for research into different kinds of prospective memory and how they are affected by different variables.

One problem which I found in this paper was that the participants were engaging in quite an unnatural prospective memory task, in which case environmental cues present during the awake phase would not help the participant in remembering to do the task. On the other hand, in the real world, such environmental cues would be present and abundant (like seeing your thesis supervisor). So in that sense, the authors can't make the claim that sleeping improves prospective memory more than staying awake and being exposed to constant pictures of monkeys.

Another interesting idea that this paper raises is the implication of sleep on prospective memory in old people. It has been found that prospective memory is one memory that is especially impaired and gets worse with old age (they keep forgetting to get the groceries for instance). Old people also get less sleep, especially sleep of the slow wave kind. Coincidence? :)


Scullin MK, & McDaniel MA (2010). Remembering to execute a goal: sleep on it! Psychological science : a journal of the American Psychological Society / APS, 21 (7), 1028-35 PMID: 20519489