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.
Caci 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
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
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.
Song 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
Why do some people like popular music while others prefer less popular genres? A new study published on the journal Psychology of Music proposes a possible explanation for this, handedness. After examining the musical preferences and the handedness scores of 92 undergraduate students, S.D. Christman identified that the strength of handedness is an important factor in individual differences in musical preferences.
More specifically, strong right-handers compared to mixed-handers reported significantly decreased liking of unpopular music genres and marginally increased liking of popular genres. These differences do not appear to reflect differences in musical training or experience. According to the author of the study handedness is associated with differences in cognitive flexibility. Previous studies suggest that strong right-handedness is associated with decreased interaction between the left and right cerebral hemispheres, which in turn is associated with decreased cognitive flexibility across various domains. The author concludes:
A number of studies report differences between conservatives and liberals in musical preferences (e.g., Glasgow & Cartier, 1985; North & Hargreaves, 2007). For example, Glashow and Cartier (1985) reported that conservatives prefer music that is safe and familiar, presumably reflecting preference for popular, not unpopular, genres. Given evidence that strong right-handedness is associated with increased conservative attitudes (Christman, 2008), this suggests a possible three-way connection between strong right-handedness, conservative views, and a lack of open-earedness. Accordingly, future research on individual differences in musical preferences would be well advised to include strength of handedness as a variable.
Finally, in case you’re curious, here are some of the genres included in each category: (a) popular: modern rock, classic rock, heavy metal, alternative rock, modern pop, 80s pop, R&B, Rap, Hip-hop, country, (b) unpopular: soul, funk, jazz, blues, folk, avant-garde, world, electronica, reggae, ambient, house. The categorisation of popular and unpopular genres was based on record sales (conventional music was defined as popular genres with high numbers of sales, while unconventional music was defined as less popular genres with lower numbers of sales). Even though the proposed idea is interesting, handedness is probably only one of the factors that might explain individual differences in musical preference. For a different approach see a recently published study by Chamorro-Premuzic et al. (2011) who found that individual differences in music consumption are predicted by uses of music and age rather than emotional intelligence, neuroticism, extraversion or openness.
Christman, S. D. (2011). Handedness and ‘open-earedness’: Strong right-handers are less likely to prefer less popular musical genres Psychology of Music : 10.1177/0305735611415751
Chamorro-Premuzic, T., Swami, V., & Cermakova, B. (2011). Individual differences in music consumption are predicted by uses of music and age rather than emotional intelligence, neuroticism, extraversion or openness Psychology of Music : 10.1177/0305735610381591
Music is a powerful tool of expressing and inducing emotions. Lima and colleagues aimed at investigating whether and how emotion recognition in music changes as a function of ageing. Their study revealed that older participants showed decreased responses to music expressing negative emotions, while their perception of happy emotions remained stable.
Emotion plays an important role in music. Even infants have been found to be capable of identifying emotions in musical excerpts (Nawrot, 2003). However, recognition of emotion in music has received little attention so far. A new study by Lima and Castro published in Cognition and Emotion examined the effects of ageing on the recognition of emotions in music. Previous studies looking at emotion recognition in other modalities have revealed that increasing age is associated with a decline in the recognition of some emotions but not others (for more information see meta-analysis by Ruffman et al. (2008)). Laukka and Juslin (2007) examined the effects of ageing on emotion recognition in music comparing young adults (around 24) and older adults (older than 65). Their results identified that older adults had more difficulty recognizing fear and sadness in both music and speech prosody, whereas no differences were observed for anger, happiness and neutrality.
The sample used by Lima et al. was of 114 healthy adults (67 female). They were aged between 17 and 84 years, and were divided into three groups with 38 participants each: younger(mean age=21.8 years), middle-aged (mean age=44.5 years) and older adults (mean age=67.2 years). Each group listened to 56 short musical excerpts that expressed happiness, sadness, fear/threat and peacefulness. Each category was consisted of 14 stimuli.
The results revealed significant age-related changes associated with specific emotions. More specifically, the authors identified a progressive decline in responsiveness to sad and scary music. No difference was found in happy music. Differences between age groups were also observed in the pattern of misclassifications for sad and peaceful music. Younger participants perceived more sadness in peaceful music, older participants perceived more peacefulness. This could be due to the structural features of peaceful and sad songs, which are both characterised by slow tempo. Future studies could further investigate this. In addition to that, Lima et al. took into account the years of musical training that the participants had. This analysis revealed a positive association between music training and the categorisation of musical emotions.
One possible explanation for the main findings of this study suggests that the decline in the recognition of particular emotions might reflect the age-related neuropsychological decline in brain regions (such as the amygdala) involved in emotion processing. Previous studies have showed that distinct brain regions are involved in the perception of different emotions (Mitterschiffthaler et al., 2007). Another possible explanation is the age-related positivity bias (Mather & Carstensen, 2005; Carstensen & Mikels, 2005). Age-related positivity bias suggests that people get older, they experience fewer negative emotions.
Future studies could attempt to identify particular brain regions involved in emotion recognition at different ages. Furthermore, since the age-related positivity bias might not be universal (older Chinese participants looked away from happy facial expressions and not from negative ones, see Fung et al., 2008), it’d be very interesting to investigate the effects of ageing on emotion recognition in music in participants from different cultures.
Lima CF, & Castro SL (2011). Emotion recognition in music changes across the adult life span. Cognition & emotion, 25 (4), 585-98 PMID: 21547762
Carstensen, L., & Mikels, J. (2005). At the Intersection of Emotion and Cognition. Aging and the Positivity Effect Current Directions in Psychological Science, 14 (3), 117-121 DOI: 10.1111/j.0963-7214.2005.00348.x
Ruffman T, Henry JD, Livingstone V, & Phillips LH (2008). A meta-analytic review of emotion recognition and aging: implications for neuropsychological models of aging. Neuroscience and biobehavioral reviews, 32 (4), 863-81 PMID: 18276008
Laukka, P., & Juslin, P. (2007). Similar patterns of age-related differences in emotion recognition from speech and music Motivation and Emotion, 31 (3), 182-191 DOI: 10.1007/s11031-007-9063-z
Mather M, & Carstensen LL (2005). Aging and motivated cognition: the positivity effect in attention and memory. Trends in cognitive sciences, 9 (10), 496-502 PMID: 16154382
Mitterschiffthaler, M., Fu, C., Dalton, J., Andrew, C., & Williams, S. (2007). A functional MRI study of happy and sad affective states induced by classical music Human Brain Mapping, 28 (11), 1150-1162 DOI: 10.1002/hbm.20337
Nawrot, E. (2003). The Perception of Emotional Expression in Music: Evidence from Infants, Children and Adults Psychology of Music, 31 (1), 75-92 DOI: 10.1177/0305735603031001325
Fung HH, Lu AY, Goren D, Isaacowitz DM, Wadlinger HA, & Wilson HR (2008). Age-related positivity enhancement is not universal: older Chinese look away from positive stimuli. Psychology and aging, 23 (2), 440-6 PMID: 18573017
Sustaining attention and blocking goal-irrelevant information is a crucial function in everyday life. Kanai and colleagues combining neuroimaging, self-report judgements and TMS found evidence that indicates that a region of the left superior parietal cortex mediates this function.
The ability to avoid distractibility varies across individuals as measured by the Cognitive Failures Questionnaire (CFQ) (Broadbent et al., 1982). Studies on twins and families have showed that the ability to maintain attention in the presence of distractors is highly heritable (Boomsma, 1998). High degree of heritability suggests that the variability might be mediated by genetic influences on the brain, which may be expressed via variability in brain structure.
This hypothesis was tested by Kanai et al. by scanning 145 healthy adult individuals and obtaining their CFQ scores. They used voxel-based morphometry (VBM) to examine whether distractibility scores predicted brain structure. Their results revealed that the level of an individual’s distractibility in everyday life was predicted by variability in regional grey matter density of the left superior parietal lobe (SPL). Highly distractable individuals had larger grey matter density at the left SPL. This particular region has been implicated in top-down attentional control in previous studies (Mevorach et al., 2009). To examine whether there is a causal relationship between this region and distractibility, Kanai et al. applied transcranial magnetic stimulation (TMS) over the left SPL of the participants while they were performing an attentional capture paradigm. The results of the experiment suggest that the left SPL plays a role in suppressing distraction from task-irrelevant salient distractors in both visual fields.
Kanai R, Dong MY, Bahrami B, & Rees G (2011). Distractibility in daily life is reflected in the structure and function of human parietal cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience, 31 (18), 6620-6 PMID: 21543590
Boomsma, D. I. (1998). Genetic analysis of cognitive failures (CFQ): a study of dutch adolescent twins and their parents. Eur. J. Pers., 12(5):321-330.
Broadbent, D. E., Cooper, P. F., FitzGerald, P., and Parkes, K. R. (1982). The cognitive failures questionnaire (CFQ) and its correlates. The British journal of clinical psychology / the British Psychological Society, 21 (Pt 1):1-16.
Mevorach, C., Shalev, L., Allen, H. A., and Humphreys, G. W. (2009). The left intraparietal sulcus modulates the selection of low salient stimuli. Journal of cognitive neuroscience, 21(2):303-315.
Does monocular viewing affect judgement of art? According to a 2008 paper by Finney and Heilman it does. The two researchers from the University of Florida inspired by previous studies investigating the effect of monocular viewing on performance on visual-spatial and verbal memory tasks, attempted to see what the results would be in the case of Art.
In particular, they recruited 8 right-eye dominant subjects (6 men and 2 women) with college education and asked them to view monocularly on a colour computer screen 10 painting with the right eye and another 10 with the left. None of the subjects was familiar with the presented paintings. Overall, each subject viewed 5 abstract expressionist and 5 impressionist paintings with each eye. Then they rated on a 1 to 10 scale four qualities of the paintings: representation (=how well the subject of the painting was rendered), aesthetics (how beautiful the painting appeared), novelty (=newness and originality of the painting), and closure (=completeness of the composition). Each quality was defined for each subject.
Monocular viewing had significant effects only in paintings in the abstract expressionist style. Impressionist paintings yielded no differences. The authors attributed this to the more concrete nature of impressionist works. Abstract expressionist paintings were rated more novel when viewed with the left eye. Moreover, the researchers found a trend for rating paintings as having more closure when they were viewed with the right eye than with the left.
The left eye primarily projects to the right superior colliculus and activation of this colliculus activates the right hemisphere’s attentional systems. The authors suggest that the results of the study provide evidence for the role of the right hemisphere in creativity and novelty processing. This seems consistent with previous research on patients with brain lesions and neuroimaging studies that have associated global processing and creativity with the right hemisphere*.
The small number of participants, however, means that the effects observed in this study must be seen with caution. Hopefully, someone will try to replicate these results involving a bigger sample in the near future.
*but also see Lindell (2010)
Finney, G., & Heilman, K. (2008). Art in the Eye of the Beholder: The Perception of Art During Monocular Viewing Cognitive and Behavioral Neurology, 21 (1), 5-7 DOI: 10.1097/WNN.0b013e3181684fe0