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Posts Tagged ‘cognitive neuroscience’

What makes things funny?

I’m planning to write a blog post about comedy in the near future. For now, you can enjoy this interesting TED talk by Peter McGraw, one of the researchers that developed the Benign Violation Theory. You can read more about it here.

Do older adults benefit from videogames?

Brain training games claim to boost your mental skills. But while practicing a game might make you better at it, research in young people has shown it doesn’t improve how well you perform other cognitive tasks in everyday life. Now a new study suggests the case may be different for adults above the age of 60. Researchers at the University of California have designed a driving game called NeuroRacer. In this Nature Video, we see how the game can improve an older player’s short-term memory and attention, skills which decline with age.

Read the original research paper here:http://dx.doi.org/10.1038/nature12486 (from Nature)

Eye Movements and Lie Detection – Another Myth?

19/07/2012 1 comment

This is not a proper post. It is more like a long tweet. Having done a similar study last year and finding no significant results I felt I had to share this with you.

You have probably heard that right-handed people look up to their right when they are telling a lie, while they look up to their left when they are telling the truth. Surprisingly, even though many people believe this is to be scientifically established, a quick google search comes up with no relevant peer-reviewed papers. Richard Wiseman and colleagues investigated this notion with three different studies. All three studies provided no evidence to support the notion. So it seems that the patterns of eye-movements do not aid lie detection.

Why did this myth survive for such a long time? Probably thanks to psychologists’ reluctance to publish negative results…

Here is the abstract:

Proponents of Neuro-Linguistic Programming (NLP) claim that certain eye-movements are reliable indicators of lying. According to this notion, a person looking up to their right suggests a lie whereas looking up to their left is indicative of truth telling. Despite widespread belief in this claim, no previous research has examined its validity. In Study 1 the eye movements of participants who were lying or telling the truth were coded, but did not match the NLP patterning. In Study 2 one group of participants were told about the NLP eye-movement hypothesis whilst a second control group were not. Both groups then undertook a lie detection test. No significant differences emerged between the two groups. Study 3 involved coding the eye movements of both liars and truth tellers taking part in high profile press conferences. Once again, no significant differences were discovered. Taken together the results of the three studies fail to support the claims of NLP. The theoretical and practical implications of these findings are discussed.

The rest of the article can be found on PLoS ONE.

Female-To-Male Transsexual People and Autistic Traits

27/05/2012 1 comment

The ‘extreme male brain’ theory suggests females with Autism Spectrum Conditions are hyper-masculinized in certain aspects of behaviour.  Jones and colleagues (2007) predicted that females with Gender Identity Disorder would have elevated  Autism Spectrum Quotient (AQ) scores.

AQ scores from five groups were compared: the first group consisted of 61 transmen (female-to-male transsexual people, the second of 198 transwomen (male-to-female transsexual people), the third one of 76 typical males, the fourth of 98 typical females, and the fifth of 125 individuals with Asperger Syndrome (AS).

Autism Spectrum Conditions (ASC) are characterized by difficulties in social interaction and communication, alongside restricted interests and repetitive behavior (APA 1994). The diagnosis of ASC is more common in males. The Extreme Male Brain (EMB) theory of autism proposed by Baron-Cohen and Hammer in 1997 attempted to explain this . According to the EMB individuals with an ASC display an extreme of the typical male pattern of cognition and behaviour.

Studies on females with ASC have found that they are hyper-masculinized in specific aspects of behaviour and cognition. Also, women with ASC report higher rates of tomboyism in childhood (Ingudomnukul et al., 2007).  Also, female-to-male (FM) transsexuals (referred to as ‘transmen’) follow a handedness pattern more similar to genetic males (less exclusively right-handed) (Green & Young, 2001) and the same has been found among women with ASC (Soper et al., 1986).

Jones et al. used the AQ to test the specific prediction from the EMB theory that transmen will have more autistic traits than typical women, and that a higher proportion will score in the ASC range for autistic traits. Their scores were compared to maleto-female transsexual people (‘transwomen’).

The AQ is a self-report questionnaire published by Baron-Cohen and colleagues in 2001 and consists of 50 item. It assesses social skills, communication skills, imagination abilities, attention switching, and attention to details.

Scores on the AQ can be used to categorise individuals as having the ‘broader autism phenotype’ (BAP: defined as AQ 23-28), ‘medium autism phenotype’ (MAP: defined as AQ 29-34) or ‘narrow autism phenotype’ (NAP: defined  as AQ 35+) (Wheelwright et al. 2010).  The transmen had significantly more autistic traits than control men and their mean AQ score lied in the BAP range. Approximately 30% of the transmen group had an AQ in the MAP or NAP range. Transmen had a 11-fold increase in the rate of NAP relative to typical males.

This study confirms clinical case studies and reports in adolescents and children that genetic females with Gender Identity Disorder (GID) have an increased number of autistic traits. The results of this study show that transmen relative to control women exhibit more autistic traits.  In addition to that, transmen had more autistic traits than control men, and their mean AQ score lies in the Broader Autism Phenotype (BAP) range.

The authors speculated:

that this increased number of autistic traits is likely to have made the transmen (in their childhood and adolescence) less able to assimilate in a female peer group, instead gravitating towards males. This may also have led to difficulties socializing in a female peer group, and a feeling of belonging more in a male group, thus increasing the probability of GID.

Very interesting findings but what I’ve been thinking while reading the paper was the possible effects of hormone treatment on the AQ scores. Jones et al. had an answer to that:

…a proportion of the transsexual groups were taking hormone treatments and for obvious ethical reasons it was not possible to control for this factor but it is of interest that analysis comparing those on or off testosterone treatment did not lead to significantly different AQ scores.

They go on suggesting that current sex steroid levels do not seem to affect AQ, which seem to depend mostly on foetal levels of sex steroids.

ResearchBlogging.orgJones RM, Wheelwright S, Farrell K, Martin E, Green R, Di Ceglie D, & Baron-Cohen S (2011). Brief report: female-to-male transsexual people and autistic traits. Journal of autism and developmental disorders, 42 (2), 301-6 PMID: 21448752

Eye Movements as an Objective Measurement of Mind Wandering

26/03/2012 3 comments

We spent a lot of time mind wandering. Cognitive neuroscience has recently started investigating this phenomenon. However, the subjective nature of mind wandering makes capturing and measuring it exceptionally difficult. As a result, there is still no way to objectively measure mind wandering. In the majority of published studies researchers ask participants at random intervals how focused they are on a given task. Uzzaman and Joordens in a recently published paper explored the use of eye movements as an objective measure of mind wandering while participants performed a reading task.

Eye movements are thought to reflect (to some degree) cognitive processes (for a brief overview of eye movement research, see the Scholarpedia entry). Uzzaman et al. study was based on an earlier paper by Reichle, Reineberg, and Schooler (2010) who suggested that eye movements may provide an objective measure of mind wandering. Reichle et al. investigated this hypothesis by comparing the fixation-duration during mind wandering and normal reading episodes. The results were very encouraging and suggested that the participants’ eye movements became progressively decoupled from the ongoing task (i.e., text processing) during mind wandering episodes.

Uzzaman et al. used a reading task coupled with a self-classified probe-caught mind wandering paradigm to obtain a subjective account of mind wandering episodes. They recruited 30 participants who were explicitly informed of the definition of mind wandering episodes prior to the start of the experiment and were instructed that they would be asked to report their mind state at random intervals. The authors defined explicitly mind wandering “as reading without text comprehension, or thinking about anything other than the text on hand”. They also provided several examples to make sure the participants fully understood the concept.

The participants read sixteen pages of “War and Peace” by Tolstoy on a computer screen while their eye movements were tracked and recorded. Randomly every 2–3 min, a probe would appear on top of the text asking what was the mind state of the participants at this specific point. Participants would have to answer to continue the experiment. On average participants received 10 probes in total, in which mind wandering was reported on 49% of them.

The eye movement behaviours of the participants were categorised into mind wandering or reading conditions, based on their self-reports. This analysis was conducted for the 5 s time interval preceding the probe for reading and wandering conditions within each participant. Nine pairs of eye movement variables were analysed (e.g., count of blinks, fixations, saccades, fixation duration, within-word regression count), which displayed different degrees of sensitivity to mind wandering.

Statistical differences were found in two of the eye movement variables, run count and  within-word regression count. Run count was defined as the “the total number of runs, where a run is two consecutive fixations within the same interest-area” and  within-word regression count as “the sum of all fixation durations from when the word was first fixated upon, till the last fixation”.  

Specifically, there were fewer within-word regressions for periods before mind wandering episodes compared to periods before reading reports (z = −2.305, p = 0.021). Also, the total run count was also lower during mind wandering episodes (z = −1.997, p = 0.046). In addition, fixation count, saccade count and total number of saccades within the interest-area were lower during mind wandering reports, although these variables fell slightly short of the conventional significance criterion (all z < −1.755,p > 0.079).

During comprehensive reading all the words were being cognitively processed deeply and effort was put forth. On the contrary, a different pattern was observed during mind wandering episodes, as it was suggested by the lower number and duration of within-word regressions that shows that the  text was not being processed deeply, and as a result limited lexical information was being extracted. As a result, reading became less effortful and more automatic.

The current study revealed a correlation between subjective reports of mind wandering, and objective ocular behaviour. These findings could be further exploited in future studies and lead to the development of algorithms that would mathematically predict the likelihood of mind wandering based on eye movements. Such a development might provide valuable insights into the neural correlates of mind wandering.
ResearchBlogging.orgUzzaman, S., & Joordens, S. (2011). The eyes know what you are thinking: Eye movements as an objective measure of mind wandering Consciousness and Cognition, 20 (4), 1882-1886 DOI: 10.1016/j.concog.2011.09.010

Reichle ED, Reineberg AE, & Schooler JW (2010). Eye movements during mindless reading. Psychological science, 21 (9), 1300-10 PMID: 20679524

Effects of Individual Differences and Culture on Eye Movements

Can fixation durations and saccade lengths in one task predict eye movements in other tasks for a given viewer? This was one of the questions posed by a Rayner and colleagues in an interesting 2007 study.

Surprisingly, only a few studies to date have addressed this issue. The first one was by Andrews and Coppola (1999), who recorded eye movements of 15 viewers while they were performing five different tasks.: (1) natural occurring eye movements in darkness, (2) viewing simple textured patterns, (3) scene perception, (4) visual search, and (5) reading. The authors concluded that apart from the visual environment, idiosyncracies also have a significant effect on eye movements.

In addition to examining the stability of eye movements across different tasks, Rayner et al also examined the possibe cultural differences influence on eye movements across the different tasks. Previous studies have provided some preliminary evidence of cultural differences. More specifically, Chua, Boland, and Nisbett (2005) examined the eye movement patterns of Chinese and native English speaking participants when looking at scenes. Cua et al found that Chinese were more likely to look at the background information in a scene, while the Americans looked at the foreground objects longer and sooner than the Chinese.

Rayner et al recruited seventy-four participants, which were divided into three different groups based on their knowledge and fluency of English and Chinese. The first group, the American group, consisted of native English speakers, the second , the native Chinese group consisted of 3 native speaking Chinese participants (who learnt to speak english later in their life), and finally, the Bilingual group consisted of Chinese participants who were either born in the USA or moved there before the age of 5. The right eye movements of each participant were tracked. All participants performed the following six tasks: (1) English reading, (2) face processing, (3) scene perception, (4) visual search, (5) Chinese character count, and (6) Chinese character search. In the English reading task, 40 English sentences were read . In the face processing and scene perception tasks, participants were shown 16 pictures of female faces and 24 pictures of scenes and asked to remember them for a later memory test. In the visual search task, participants were asked to find a brown square that was part of an array of brown circles and pink squares. In the Chinese character count task, participants counted the occurrences of a Chinese character in a paragraph of Chinese text. Finally, the participants who could read Chinese read 36 Chinese sentences.

Fixation duration and saccade size were used as primary indices of temporal and spatial processing in the tasks.

It is generally assumed (see Rayner, 1998) that (1) fixation duration reflects the time needed to process the informa-tion around fixation and the time needed to plan the next saccade and (2) saccade size is related to how much information can be processed on a fixation and how the next saccade target is selected.

The results of the present study suggest that fixation durations for a given individual tend to be fairly stable across different tasks. For the American and Bilingual groups, fixation durations in English reading did not correlate especially well with fixation durations in the other tasks, while for the Chinese group fixation durations in English reading did tend to correlate highly with the other tasks. Fixation durations in scene perception and face processing were highly correlated across all three participant groups. Saccade length did not correlate as well across tasks as did fixation duration. The correlations, however, tended to be positive when the reading tasks were eliminated from the analysis.

No correlation was found between fixation duration and saccade length across all of the tasks. According to Rayner et al this could be evidence that the mechanism responsible for determining when to move the eyes is largely independent of the mechanism responsible for determining where to move the eyes next.

Reading visual tasks are in general more understood than other visual tasks. The correlations in fixation durations for these different tasks does, however, suggest that there might be common aspects of processing between them. The nature of these mechanisms is not very clear. Rayner et al. suggest that:

Perhaps in non-reading tasks, some kind of timing mechanism determines when the eyes move; such a common timing mechanism would be expected to lead to correlations across tasks, particularly in fixation durations (and to a lesser extend, saccade length). Another possibility is that something like visual saliency.

Another interesting finding of this study was that the more experience participants had with either English or Chinese, the shorter the fixations and the longer the saccades they made. This effect did not depend on cultural characteristics of the participants. As far as the effect of culture on eye movements is concerned, only a few differences were identified. Chinese participants had systematically shorter fixations in the scene perception, face processing, and Chinese count tasks than the Americans. Their performance was similar on the two search tasks. The difference in the duration of fixation observed between Chinese and American participants is due to the Chinese trading off number of fixations with fixation duration. In other words, while they made somewhat shorter fixations, they also made slightly more fixations.

ResearchBlogging.orgRayner K, Li X, Williams CC, Cave KR, & Well AD (2007). Eye movements during information processing tasks: individual differences and cultural effects. Vision research, 47 (21), 2714-26 PMID: 17614113

“Owls” more likely to have ADHD?

07/12/2011 6 comments
Is there any relationship between chronotype and Attention-deficit hyperactivity disorder (ADHD) symptoms? Are evening oriented individuals more likely to have ADHD? This was the main question posed in a (relatively) recent article by Caci and colleagues.

ADHD is the most common neurodevelopmental disorder (Faraone et al., 2003) and affects about 3–6% of children (Tannock 1998). ADHD is defined by either an attentional dysfunction, hyperactive/impulsive behaviour or both (DSM-IV; American Psychiatric Association, 1994). Therefore, the diagnosis of ADHD has three subtypes: the Inattentive subtype (ADHD/IA), which is characterised by significant levels of inattention but subthreshold levels of hyperactive/ impulsive symptoms, the Hyperactive/Impulsive subtype (ADHD/HI), which is defined by hyperactivity/ impulsivity but not of inattention symptoms, and the Combined Inattentive-Hyperactive/Impulsive subtype (ADHD/C), which is characterised by maladaptive levels of both symptom clusters.

Morningness is a stable characteristic which reflects the phase of circadian system. It is a continuum with evening types at one end and morning types on the other. Previous studies have found that the evening orientation might be a risk factor for various disorders including depression and personality disorders. Morningness is also a heritable trait (Vink, Groot, Kerkhof, & Boomsma, 2001) and determined by genetic factors (Mishima, Tozawa, Satoh, Saitoh, & Mishima, 2005). Impulsivity and novelty seeking, two characteristics associated with particular ADHD subtypes are negatively related to morningness. Specifically, evening oriented individuals often score higher on tests assessing those traits. In addition to that, there is evidence that morningness is implicated in the variation of performance (Natale, Alzani, & Cicogna, 2003). Variability in various cognitive tasks is a common finding in many studies examining individuals with ADHD. Individuals with ADHD have also been found to experience a number of sleep related disorders such as sleep-onset difficulties, agitated sleep, and a higher number of nocturnal awakings.

Caci et al. examined the relationship between morningness and ADHD. Their hypothesis was that adults suspected of having ADHD are more evening oriented than are adults without ADHD. They recruited 354 participants and assessed their scores in the Composite Scale of Morningness (CSM), a measure of morningness, and the Adult Self-Report Scale v1.1 (ASRS), a self-reported questionnaire used for screening of ADHD in adults. ASRS includes two subscales for inattention and hyperactivity symptoms. This allowed Caci et al to examine the relationship between possible ADHD subtypes and morningness.

The results of the study confirmed the hypothesis; participants with higher scores on the ASRS reported having an evening orientation. The effect was stronger in participants with higher scores on the subscale of inattention. No correlation was found between hyperactivity and morningness. This provides evidence for the existence of different endophenotypes in ADHD. Since the sample used in this study consisted of healthy volunteers, it would be interesting to try to replicate this finding in diagnosed individuals with ADHD.

PS: After writing this post, I realised there’s a new study published in Nature by Baird et al. (2011) that examines endocrine and molecular levels of circadian rhythms in ADHD and seems to confirm the morningness hypothesis proposed by Caci et al. According to this paper, adult ADHD is accompanied by significant changes in the circadian system. I might write a post about it in the near future.

 

ResearchBlogging.orgCaci H, Bouchez J, & Baylé FJ (2009). Inattentive symptoms of ADHD are related to evening orientation. Journal of attention disorders, 13 (1), 36-41 PMID: 19387003

Ode To The Brain

03/12/2011 1 comment

The Symphony of Science is a musical project of John D Boswell, designed to deliver scientific knowledge and philosophy in musical form. The project owes its existence in large measure to the classic PBS Series Cosmos, by Carl Sagan, Ann Druyan, and Steve Soter, as well as all the other featured figures and visuals. Continuation of the videos relies on generous support from fans and followers.

Read more about the project here.

Here’s one of my favourites, “Ode To The Brain”.

Investigating the Anatomical Relationship Between Primary Sensory and Prefrontal Cortices in the Human Brain

11/10/2011 1 comment

People experience the world in slightly different ways. Philosophers have been writing about this for years and, recently, studies using psychophysics and neuroimaging provide further support for this. A classic example is the way we perceive visual illusions; there is variability in the responses of people about the extent they experience various illusions. Schwarzkopf et al. (2010) showed that inter-individual differences in the surface area of V1 predict individual differences in conscious perception, such as how big something looks.

A study by Chen et al. that was published on the  JoN used a novel approach that combined non-invasive cortical functional mapping with whole-brain voxel-based morphometric analyses to investigate the anatomical relationship between the functionally mapped visual cortices and other cortical structures in healthy humans. Chen et al. found an interesting correlation between the size of V1 and primary auditory cortex. This relationship could be explained in terms of our everyday multisensory experience of the world. However, the size of those areas was anticorrelated with the size of the anterior prefrontal cortex (aPFC), the frontopolar part of the frontal cortex. In a few words, individuals with larger primary visual cortex had larger primary auditory cortex but smaller aPFC. This anticorrelation was only found for the primary sensory cortices and not for other visual cortices (e.g. V2, V3).

According to Chen et al.

…while one might expect a positive correlation between the whole-brain gray matter volume and the volume of its components, instead we found a striking anticorrelation for primary visual cortex: individuals with larger brains tended to have smaller primary visual cortices. In contrast, anterior prefrontal cortex was the single most enlarged region in a larger brain.

The aPFC is a particularly fascinating area. Apart from having many names (anterior PFC, the frontal pole, frontopolar cortex, rostral prefrontal cortex, BA 10…), aPFC is larger relative to the rest of the brain (Semendeferi et al., 2001) and is significantly different in humans compared to other primates (Semendeferi et al., 2001), suggesting that this region may contribute to the unique human behaviour. Furthermore, it is one of the last brain areas to mature in humans (Dumontheil et al., 2008) and has been recently identified as the region with the greatest relative prediction power about brain maturity over development (Dosenbach et al., 2011). Evidence from previous studies suggest that this particular area has a role in higher-order cognitive functions (including prospective memory)

The pairing between the expansion of anterior prefrontal cortex and the contraction of primary sensory cortices reflects a common ground for the formation of anatomically and phylogenetically remote cortical regions, and suggests the existence of a reciprocal link between high-order cognition and low-level sensation.

Future studies will attempt to further investigate this relationship and examine what the effects of these structural differences are on function and performance on various tests thought to tap on those areas.

ResearchBlogging.orgSong C, Schwarzkopf DS, Kanai R, & Rees G (2011). Reciprocal anatomical relationship between primary sensory and prefrontal cortices in the human brain. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31 (26), 9472-80 PMID: 21715612

Schwarzkopf DS, Song C, & Rees G (2011). The surface area of human V1 predicts the subjective experience of object size. Nature neuroscience, 14 (1), 28-30 PMID: 21131954

Coren S, & Porac C (1987). Individual differences in visual-geometric illusions: predictions from measures of spatial cognitive abilities. Perception & psychophysics, 41 (3), 211-9 PMID: 3575080

Dumontheil I, Burgess PW, & Blakemore SJ (2008). Development of rostral prefrontal cortex and cognitive and behavioural disorders. Developmental medicine and child neurology, 50 (3), 168-81 PMID: 18190537

Semendeferi, K., Armstrong, E., Schleicher, A., Zilles, K., & Van Hoesen, G. W. (2001). Prefrontal cortex in humans and apes: a comparative study of area 10 American journal of physical anthropology, 3 (114), 224-241

Dosenbach NU, Nardos B, Cohen AL, Fair DA, Power JD, Church JA, Nelson SM, Wig GS, Vogel AC, Lessov-Schlaggar CN, Barnes KA, Dubis JW, Feczko E, Coalson RS, Pruett JR Jr, Barch DM, Petersen SE, & Schlaggar BL (2010). Prediction of individual brain maturity using fMRI. Science (New York, N.Y.), 329 (5997), 1358-61 PMID: 20829489

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