Journal Pre-proof Neuroanatomy of creative achievement Christopher J. Wertz, Muhammad O. Chohan, Ranee A. Flores, Rex, E. Jung PII:
S1053-8119(19)31078-X
DOI:
https://doi.org/10.1016/j.neuroimage.2019.116487
Reference:
YNIMG 116487
To appear in:
NeuroImage
Received Date: 1 August 2019 Revised Date:
12 December 2019
Accepted Date: 20 December 2019
Please cite this article as: Wertz, C.J., Chohan, M.O., Flores, R.A., Jung, R.,.E., Neuroanatomy of creative achievement, NeuroImage (2020), doi: https://doi.org/10.1016/j.neuroimage.2019.116487. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2019 Published by Elsevier Inc.
Neuroanatomy of Creative Achievement
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Christopher J. Wertz1, Muhammad O. Chohan1, Ranee A. Flores1, Rex, E. Jung1
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1
University of New Mexico Department of Neurosurgery. Albuquerque, NM USA
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Abstract Very few studies have investigated neuroanatomical correlates of “everyday” creative
9
achievement in cohorts of normal subjects. In previous research, we first showed that scores on
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the Creative Achievement Questionnaire (CAQ) were associated with lower cortical thickness
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within the left lateral orbitofrontal gyrus (LOFG), and increased thickness of the right angular
12
gyrus (AG) (Jung et al., 2010). Newer studies found the CAQ to be associated with decreased
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volume of the rostral anterior cingulate cortex (ACC) (Chen, et al., 2014), and that artistic and
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scientific creativity was associated with increased and decreased volumes within the executive
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control network and salience network (Shi et al., 2017). We desired to replicate and extend our
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previous study in a larger cohort (N=248), comprised of subjects studying and working in
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science, technology, engineering, and math (STEM). Subjects were youn (Range = 16-32; Mean
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age = 21.8; s.d. = 3.5) all of whom were administered the CAQ from which we derived artistic
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and scientific creativity factors. All subjects underwent structural MRI on a 3 Tesla scanner from
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which cortical thickness, area, and volume measures were obtained using FreeSurfer. Our results
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showed mostly cortical thinning in relation to total, scientific, and artistic creative achievement
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encompassing many regions involved in the cognitive control network (CCN) and default mode
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network (DMN).
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Introduction
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The science of creative cognition has branched off from broad, behaviorally directed
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studies initially investigating convergent and divergent thinking, (Sternberg & Lubart, 1999;
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Torrance, 1976), to more specific studies designed to measure the construct of creativity and how
29
it is manifested in the structure and function of the brain. Currently, creative cognition is broadly
30
measured through three domains, creative potential (an individual’s cognitive ability to create
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something that is both novel and useful (Jauk, Benedek, & Neubauer, 2014; Stein, 1953),
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everyday creativity (a regular individual’s ability to create something original in everyday life,
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(Richards, 2010) and creative achievement (an individual’s real-life creative contribution, such
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as writing a screenplay for a film (Carson, Peterson, & Higgins, 2005). The creativity field
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further dissects these constructs, with several domains of assessing creative novelty such as
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divergent thinking, fluency, imagery, reasoning, and insight. Research consistencies regarding
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neural correlates within these creative fields remains sparse and inconclusive, largely lacking
38
consensus or replication (Arden, Chavez, Grazioplene, & Jung, 2010; Beaty, Nusbaum, & Silvia,
39
2014). The question remains: what best measures certain people’s proficiency to produce work
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that is both novel and useful, and how is this manifested in their brain structure and function?
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Creative achievement driven tasks are a construct of creative cognition that objectively
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measures individuals’ ability to produce work that is both novel and useful (Simonton, 2012).
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The Creative Achievement Questionnaire (CAQ; Carson et al., 2005) offers a reliable (0.81) and
44
valid measure of real-life creative productivity across ten specific domains ranging from culinary
45
prowess to scientific innovations. The CAQ is well correlated with measures of divergent
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thinking such as originality and fluency and, while divergent thinking tests predict creative
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success (Torrance, 1988), they are limited in their ability to predict real-life applications. While
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the objective consensus of the CAQ is a considerable strength, one major problem in using the
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CAQ is that scores are always highly skewed. For example, few people in a normal, non-
50
eminent, sample will have higher scores than the average (of zero). Those few people, however,
51
have accomplished real-life creative contributions of novelty or usefulness as evidenced by
52
patents, published works, and awards. Higher scores on CAQ are therefore eliciting the desired
53
effect in researching creative cognition manifested in creative products in the world recognized
54
by others in terms of their novelty and utility.
55
Recent behavioral research on creative achievement has found it to be moderately
56
correlated with intelligence – as measured by the intelligence quotient (IQ) – and openness
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(Jauk et al., 2014), as well as artistic and scientific achievement (Kaufman et al., 2016). Another
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study, found that intentional mind wandering was predictive of greater creative achievement
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(Agnoli, Vanucci, Pelagatti, & Corazza, 2018). Relatively few studies have been conducted
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regarding neuroanatomical correlates of creative achievement. Jung et al., first showed that
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individuals with higher scores on the CAQ had lower cortical thickness within the left lateral
62
orbitofrontal gyrus (LOFG), and increased thickness of the right angular gyrus, (Jung et al.,
63
2010). Subsequent studies demonstrated that the CAQ was associated with increased cortical
64
volume of the superior frontal gyrus, ventromedial prefrontal cortex and decreased volume in the
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dorsal and rostral anterior cingulate cortex (ACC), (Chen et al., 2014). Shi et al., further parsed
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two major domains of the CAQ by extracting artistic and scientific factors (Carson et al., 2005;
67
Kaufman et al., 2016). They found that decreased volume in the supplementary motor area and
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ACC was associated with artistic creativity, while increased volume in the middle frontal gyrus
69
and inferior occipital gyrus was associated with scientific creativity, (Shi, Cao, Chen, Zhuang, &
70
Qiu, 2017). Functional connectivity studies using CAQ have found networks negatively
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correlated with medial superior frontal gyrus, middle frontal gyrus, orbitofrontal insula, thalamus
72
(Chen et al., 2014). There is no commonality of findings to report across studies, and differences
73
could be attributed to methodological differences between studies (the last two of which are from
74
the same experimental cohort), including: restriction of creative range, use of different
75
covariates, and unbalanced sex distributions.
76
Our current study was designed to replicate and extend our previous research by looking
77
at CAQ scores in a larger independent healthy young sample across cortical thickness, surface
78
area and volume. We also investigated the artistic creativity and scientific two factor model
79
suggested by (Carson et al., 2005) and explored by (Shi et al., 2017). Previous research has
80
shown both increased and decreased volumes across the salience, executive, default mode
81
network (DMN), and cognitive control network (CCN) in relation to high creativity scores
82
(Beaty, Christensen, Benedek, Silvia, & Schacter, 2017; Jung, Mead, Carrasco, & Flores, 2013).
83
We, therefore, predict findings to be associated with the CCN and DMN, specifically, increased
84
gray matter in areas of the superior parietal cortex and decreased prefrontal frontal areas with
85
CAQ total. Based on previous work using the CAQ two factor model, we predict similarly
86
decreased gray matter in the ACC with artistic creativity and increased gray matter in the parietal
87
cortex as well as the caudal middle frontal gyrus.
88 89
Methods
90
Two hundred and sixty science, technology, engineering and mathematics (STEM)
91
subjects either working in the field or studying within STEM fields were recruited for the current
92
study. Six subjects were excluded based on missing behavioral data and six subjects were
93
excluded due to incidental MRI findings (e.g., arachnoid cyst), leaving a sample of two hundred
94
and forty-eight.
95
Subjects ranged from (16-32) years of age (21.8 ± 3.5 years), and were well matched by sex (127
96
males, 121 females). They were recruited by postings in various departments and classrooms,
97
around the University of New Mexico, local high schools and various professional STEM related
98
businesses. All subjects signed a consent form approved by the institutional review board of the
99
University of New Mexico prior to participation. Prior to entry into the study, subjects were
100
screened and met no criteria for neurological and psychological disorders that would impact
101
experimental hypotheses (e.g., learning disorders, traumatic brain injury, major depressive
102
disorder). Subjects were also screened for conditions that would prohibit undergoing an MRI
103
scan (e.g., orthodontic braces, claustrophobia). Subjects were compensated $100 for undergoing
104
four hours of cognitive testing, encompassing measures of intelligence, creativity, problem
105
solving, personality, and aptitude, as well as a 30-minute MRI.
106 107
Behavioral Measures
108
All subjects completed the CAQ, a reliable and valid measure of creative achievement across 10
109
domains including visual arts, music, creative writing, dance, drama, architecture, humor,
110
scientific discovery, invention, and culinary arts. In each domain the subject places a checkmark
111
next to a concrete achievement. Each domain has a potential point range of 0-7. Several items if
112
checked were denoted with an asterisk where the subject was required to indicate how many
113
times each achievement occurred (e.g., “I have been published in scientific journals”) and then
114
multiplied by item number. The CAQ total score is tallied by summing across the ten domains. A
115
two-factor model was created based on Carson et al., dividing the ten domains into a science and
116
art total score, (Carson et al., 2005). Creative achievement in the arts represented the sum of
117
scores for drama, humor, music, dance, visual arts, creative writing, and theater/film. Creative
118
achievement in the sciences represented the sum of inventions and scientific discovery.
119
To assess general intelligence, subjects were administered the Wechsler Abbreviated
120
Scale of Intelligence (WASI-II). The WASI battery consists of subtests that measure verbal and
121
non-verbal mental abilities that contribute to general intelligence. We derived a Full-Scale
122
Intelligence Quotient (FSIQ) score from performance on the subtests of similarities, matrix
123
reasoning and block design.
124 125
Neuroimaging
126
Structural imaging was obtained at a 3 Tesla Siemens scanner using a 32-channel head coil to
127
obtain a T1 5 echo sagittal MPRAGE sequence [TE = 1.64 ms; 3.5 ms; 5.36 ms; 7.22 ms; 9.08
128
ms; TR = 2530 ms; voxel size = 1.0×1.0×1.0 mm3; FOV = 256 mm; slices = 192; acquisition
129
time = 6:03]. For all scans, each T1 was reviewed for image quality. Cortical reconstruction and
130
volumetric segmentation were performed with the FreeSurfer-v5.3.0 image analysis suite. The
131
methodology for FreeSurfer is described in full in several papers (Fischl et al., 2002, 2004;
132
Ségonne, Pacheco, & Fischl, 2007). Briefly, this process includes automated Talairach
133
transformation, segmentation of the subcortical white matter and deep gray matter volumetric
134
structures, (Fischl et al., 2002, 2004). Segmented data were then parceled into units based on
135
gyral and sulcal structure, resulting in values for cortical thickness, surface area, and volume
136
(Desikan et al., 2006; Fischl et al., 2004). The results of the automatic segmentations were
137
quality controlled, and any errors were manually corrected. Volume measures are a combination
138
of thickness (a one-dimensional measure) and area (a two dimensional measure) across 33
139
measures per hemisphere (i.e., 66 across the surface of the brain) as well as seven subcortical
140
volumes per hemisphere (i.e., 14 across the brain) including bilateral caudate, putamen, globus
141
pallidus, nucleus accumbens, thalamus, amygdala, and hippocampus (Fischl et al., 2002).
142 143
Statistical Analysis
144
General linear models were used to assess correlations with CAQ total, art total, and science total
145
scores with cortical volume, area, and thickness. This type of analysis was performed by the
146
Query, Design, Estimate, Contrast (QDEC) interface within FreeSurfer. First, each subject’s
147
surface was smoothed using a full-width/half-maximum gaussian kernel of 10 mm. This
148
smoothing was done so that all subjects in this study could be displayed on a common template,
149
which is an average brain in Talairach space. Each design matrix consisted of either CAQ total,
150
art total, or science total raw scores as the independent variable and sex, age, FSIQ and the
151
FreeSurfer calculation of total brain volume categorized as BrainSegVolNotVent as covariates
152
and the slope used was different offset/intercept, different slope (DODS).Correction for multiple
153
comparisons was performed using a Monte Carlo Null-Z simulation method. For these analyses,
154
a total of 10,000 simulations were performed for each comparison, using a threshold of p = 0.05.
155
This is the probability of forming a maximum cluster of that size or larger during the simulation
156
under the null hypothesis and presents the likelihood that the cluster of vertices would have
157
arisen by chance. Multiple regressions were performed on subcortical volume measures, against
158
each factor (CAQ, art, science total scores), controlling for total brain volume, age, sex and
159
FSIQ. We used R version 3.5.3 for Windows for all behavioral statistical analysis.
160 161
162 163
Results CAQ total score, art total, and science total were all highly skewed and therefore any
164
outliers greater than three standard deviations from the mean were excluded by variable.
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Behavioral characteristics are presented in Table1). Previous studies on creative achievement
166
have specifically found it to be moderately correlated with intelligence. In our sample,
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CAQ total was weakly correlated with FSIQ (r = 0.06, p = 0.35). As expected, the art factor
168
score was weakly correlated with FSIQ (r = 0.004, p = 0.95) and the science factor was
169
significantly correlated with FSIQ (r = 0.13, p = 0.05). Our sample was selected to sample
170
STEM populations, among whom CAQ-IQ scores are known to be more highly correlated;
171
therefore, controlling for IQ was deemed necessary for accurate interpretation of results. It
172
should be noted, when we ran the same analyses without controlling for IQ, CAQ total did
173
not have any significant associations with cortical structures, artistic creativity findings
174
remained the same, and scientific creativity retained largely the same findings except for
175
right hemisphere postcentral, and precentral regions. The significant associations remained
176
negative, which is consistent with findings when controlling for IQ.
177
Subcortical Analysis
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A series of multiple regression analyses investigated subcortical volume correlates with CAQ
179
total, art total and sci total. We regressed all subcortical volume measures, against each measure
180
controlling for total brain volume, age, sex and FSIQ. CAQ total score was predicted by a model
181
that included increased left hippocampus and increased posterior corpus callosum volumes (F =
182
3.1, p = 0.006; r2 = 0.07). A model including decreased left amygdala and increased left caudate
183
volume predicted artistic creativity total score (F = 2.24, p = 0.040; r2 = 0.05). Scores on
184
scientific creativity factor were predicted by a model including increased mid-anterior corpus
185
callosum and decreased left thalamus volumes (F = 8.41, p <0.001; r2 = 0.18).
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Behavioral Demographics
Mean
Std. Dev.
Range
FSIQ
111.6
11.9
80-153
CAQ Total
16.7
14.9
0-74
CAQ Art
9.6
9.8
0-66
CAQ Science
4.3
5.1
0-24
187 188
Table 1. Descriptive statistics of participant’s demographics and behavioral measures.
189
Cortical Analysis
190
CAQ Cortical Analysis
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The results of whole brain cortical analysis with CAQ total score showed significantly decreased volume
192
in the left insula extending into the superior temporal gyrus after multiple comparisons correction (p <
193
0.05). Table 2 and Fig.1 present the results of the statistical maps and linearity. r = -0.114
194
L L Insula Volume
195 196 197
CAQ Volume
198 199 200
-5.00 -2.50 0.00
2.50
5.00
CAQ_Total
201 202 203
Figure 1. Statistical map showing significantly decreased cortical volume with CAQ total scores overlaying the Desikan-Killianey atlas.
Cortical Surface
Max
Size(mm2)
TalX
TalY
TalZ
CWP
Vtxs
Gyrus
Volume
-2.704
1137.90
-36.6
-5.6
-10.3
0.03960
2250
insula
204 205 206 207 208
Table 2. Creative Achievement Questionnaire: Regions surviving Monte Carlo simulation (p < 0.05). Size (mm2) = size of region in square millimeters; TalX = Talairach region X plane; TalY = Talairach region Y plane; TalZ = Talairach region Z plane; CWP cluster-wise probability; Vtxs = number of contiguous vertices.
209
Artistic Creativity Cortical Analysis
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The results of whole brain cortical analysis with CAQ artistic creativity total score showed significantly
211
decreased thickness in the left superior temporal gyrus extending into the middle temporal gyrus and right
212
superior parietal gyrus, after multiple comparisons correction (p < 0.05). Table 3 and Fig.2 present the
213
results of the statistical maps and linearity.
214 215 216
219 220 221
-5.00 -2.50 0.00
2.50
R Superior Parietal
218
5.00
CAQ Artistic Creativity
222 223 224
r = -0.153
r = -0.102
L Superior Temporal
217
R Thickness
L Thickness
Figure 2. Statistical maps showing significantly decreased cortical thickness with artistic creativity overlaying the Desikan-Killianey atlas.
225 Cortical Surface
Max
Size(mm2)
TalX
TalY
TalZ
CWP
Vtxs
Gyrus
Thickness
-2.871
1583.53
-44.7
5.9
-19.8
0.00580
3233
LH superior temporal
Thickness
-2.883
536.50
24.1
-73.3
32.2
0.02050
769
RH superior parietal
226 227 228 229 230
Table 3. Creative Achievement Factor Artistic Creativity: Regions surviving Monte Carlo simulation (p < 0.05). Size (mm2) = size of region in square millimeters; TalX = Talairach region X plane; TalY = Talairach region Y plane; TalZ = Talairach region Z plane; CWP cluster-wise probability; Vtxs = number of contiguous vertices.
231
Scientific Creativity Cortical Analysis
232
The results of whole brain cortical analysis with CAQ scientific creativity total score showed significantly
233
decreased surface area in the left insula gyrus extending into regions of the superior temporal gyrus,
234
transverse temporal gyrus, and another significant region in the precentral and postcentral gyrus. In the
235
right hemisphere we found significantly decreased area in numerous regions of the brain including left
236
superior frontal gyrus extending into the caudal middle frontal gyrus, middle temporal gyrus extending
237
into the superior temporal gyrus, cingulate gyrus, and pars-opecularis gyrus extending into the insula and
238
precentral gyrus. We also found a sole positive significant correlation in the right hemisphere postcentral
239
gyrus extending into the superior parietal gyrus with volume, after multiple comparisons correction (p <
240
0.05). Table 4 and Fig. 3 and 4, present the results of the statistical maps and linearity.
R Are L Insula area
242 243 244 245
r = -0.149
r = -0.122 R Superior Frontal area
L 241
246 -5.00 -2.50 0.00
247 248 249
2.50 5.00
CAQ Scientific Creativity
Figure 3. Statistical maps showing significantly decreased cortical surface area with scientific creativity overlaying the Desikan-Killianey atlas.
L
R Postcental Volume
r = 0.196
-5.00 -2.50 0.00 2.50 5.00
CAQ Scientific Creativity 250 251 252
Figure 4. Statistical maps showing significantly increased cortical volume with scientific creativity overlaying the Desikan-Killianey atlas.
Cortical Surface
Max
Size(mm2)
TalX
TalY
TalZ
CWP
Area
-3.871
3138.68
-33.7
-8.8
9
0.00010
7748
LH insula
Area
-3.131
1178.73
-19.3
-21.2
55.6
0.01860
2851
LH precentral
Area
-3.617
1756.45
19.8
25.3
41.1
0.00110
3149
RH superior frontal
Area
-3.228
1583.37
44
-26.7
-3.5
0.00280
3214
RH superior temporal
Area
-3.169
1118.04
48.1
-0.6
9.4
0.03150
2786
RH precentral
Area
-2.624
1225.18
9.1
-31.5
27.8
0.01810
3009
RH isthmus cingulate
Volume
4.248
639.44
16.4
-28.8
69.1
0.00770
1595
RH postcentral
Vtxs
Gyrus
253 254 255 256
Table 4. Creative Achievement Factor Scientific Creativity: Regions surviving Monte Carlo simulation (p < 0.05). Size (mm2) = size of region in square millimeters; TalX = Talairach region X plane; TalY =
257 258
Talairach region Y plane; TalZ = Talairach region Z plane; CWP cluster-wise probability; Vtxs = number of contiguous vertices.
259
Discussion
260
The current study sought to replicate and extend our previous cortical structural findings
261
by exploring the relationship with creative achievement in a normal non-eminent sample. Our
262
results failed to replicate our previous findings of decreased cortical thickness in the left
263
orbitofrontal cortex or increased thickness in the right angular gyrus. We adopted a more
264
complex analysis strategy involving thickness, area, and volume, and instead discovered several
265
new brain regions, where highly creative individuals exhibited cortical structural differences,
266
across a wide network previously implicated in creativity research. Indeed, we found numerous
267
regions to overlap both the DMN (bilateral superior temporal gyri and isthmus cingulate gyrus)
268
and CCN (insula, superior parietal and preSMA). Perhaps more surprisingly, we only found
269
increased volume in relation to scientific creativity in the right postcentral gyrus.
270
The general pattern across morphological studies within the creative achievement
271
tends to show decreased volume (particularly within the DMN) more than increased
272
volumes (Jung et al., 2013). It has been hypothesized that cortical thinning represents greater
273
efficiency and lower levels of plasticity the more proficiently one acquires a particular skill (Jung
274
et al., 2010). However, studies looking at creative potential prominently find increased
275
volume in several areas including the bilateral precuneus, posterior cingulate cortex and
276
the bilateral caudate (Fink et al., 2014; Jauk, Neubauer, Dunst, Fink, & Benedek, 2015).
277
Our results showed decreased volume to be associated with higher CAQ total scores in the left
278
insula extending into the superior temporal gyrus, and increased volume in the left hippocampus
279
and posterior corpus callosum. The left hemisphere regions associated with CAQ, including the
280
insula and superior temporal gyrus have been shown to overlap with the DMN and salience
281
networks respectively (Beaty et al., 2017), and are implicated in fMRI studies looking at verbal
282
creativity (Boccia, Piccardi, Palermo, Nori, & Palmiero, 2015). Left insular activation was found
283
during a brainstorming task in a study looking at neuro-correlates of creative writing (Shah et al.,
284
2013). The left superior temporal lobe has been found to be active during imagination type tasks
285
(Huang et al., 2013), and decreased volume has been correlated with high imagination ability,
286
(Jung, Flores, & Hunter, 2016). Finally, research has demonstrated a role for the hippocampus in
287
creativity, as patients with lesions to the hippocampus are found to have lower scores on
288
measures of divergent thinking (Duff, Kurczek, Rubin, Cohen, & Tranel, 2013). Our finding of
289
increased volume in relation to creative achievement in the posterior corpus callosum is in
290
contrast to other studies finding an inverse relationship in size with higher divergent thinking
291
scores (Gansler et al., 2011).
292
Within the artistic creativity measure we found an inverse relationship with thickness in
293
the left superior temporal gyrus extending into the middle temporal gyrus and right superior
294
parietal gyrus. As previously noted, the left superior-middle temporal gyrus is involved in verbal
295
creativity and imagination. The right superior parietal lobule is involved in mentally re-ordering
296
the sequence of visual stimuli, (Gansler et al., 2011). Zhu et al., found the bilateral superior
297
parietal cortex to be inversely associated with verbal and visual creativity (Zhu et al., 2017). We
298
also observed higher artistic creativity in relation to decreased left amygdala volume and
299
increased volume in the left caudate. The amygdala has been implicated in artistic creativity, is
300
associated with spontaneous and emotional functioning, and has been implicated in numerous
301
musical creativity studies (Bashwiner, Wertz, Flores, & Jung, 2016; McPherson, Barrett, Lopez-
302
Gonzalez, Jiradejvong, & Limb, 2016). Finally, increased left hemispheric activation in the left
303
caudate nucleus was observed in expert creative writers in contrast to non-experts (Erhard,
304
Kessler, Neumann, Ortheil, & Lotze, 2014). Within scientific creativity, we found several inverse relationships with surface area and
305 306
high scientific creative scores. We found significantly decreased surface area in the left insula
307
and precentral gyrus. Left precentral gyrus is activated during visuo-spatial creativity tasks
308
(Boccia et al., 2015). The insula is involved in general and fluid intelligence (Haier, Jung, Yeo,
309
Head, & Alkire, 2004; Woolgar et al., 2010). The right hemisphere findings revealed several
310
negative correlations in the superior frontal gyrus, which has also been found with higher
311
divergent thinking performance anticorrelated within the superior frontal regions. However,
312
other studies have found increased volume in right superior frontal gyrus to be correlated with
313
creativity and cognitive flexibility (Kühn et al., 2014). Scientific creative achievement is
314
hypothesized to rely more heavily on convergent thinking processes in the pursuit of solving one
315
specific goal. Indeed, many of our findings overlap with previous work with convergent
316
thinking. For example, Jung-Beeman et al., 2004 found that solving problems through a modified
317
form of Mednick’s test activated the right anterior superior temporal gyrus (Jung-Beeman et al.,
318
2004).
319
The literature regarding the neuroscience of creativity is in a nascent stage, characterized
320
by disparate and divergent findings across laboratories. Previous research within the
321
neuroscience of intelligence has found similar dissimilarities to be associated with such
322
seemingly subtle effects as those associated with analysis techniques and covariates chosen
323
(Martínez et al., 2017). Thus, it is not surprising that we have found results different from those
324
found previously, as such differences can be caused by different analysis packages, sample
325
characteristics, and covariates applied. Similarly, our sample focused on STEM subjects, while
326
previous samples looked at more broadly distributed subject cohorts. Finally, the interplay
327
between intelligence (or IQ) and creativity, is an important one, with the potential interaction
328
providing potential differences between studies that either use IQ as a covariate and those that do
329
not. A special issue has recently been published in Neuropsychologia with several perspectives
330
regarding the “common ground and differences” between these two cognitive constructs
331
(Benedek, Jung, & Vartanian, 2018). There are only a handful of studies in existence regarding
332
structural correlates regarding the CAQ, and further research in this area will be critical to
333
establish convergence over time, as has been evident in creative neuroscience more broadly
334
(Jung et al., 2013). However, as currently comprised, the literature regarding structural correlates
335
of the CAQ now shows both increased and decreased volume in relation to higher creative
336
achievement (Chen et al., 2014; Jung et al., 2010; Shi et al., 2017).
337
Previous studies in creativity neuroscience have implicated broad regions overlapping
338
significantly with the DMN (Bashwiner et al., 2016; Beaty, Benedek, Kaufman, & Silvia, 2015;
339
Kühn et al., 2014) and the CCN (Chrysikou, Weber, & Thompson-Schill, 2014; Li, Yang, Zhang,
340
Li, & Qiu, 2016). The current findings appear to conform with the hypothesis regarding dynamic
341
interplay between DMN and CCN (mediated by the SN) as our results implicated several areas
342
across these broad networks. Thus, these two specific subdomains of creativity require a
343
dynamic interconnection of the DMN and CCN in order to achieve success in the creative arts
344
and sciences.
345
There are several limitations to the current study. Our sample was restricted to a healthy
346
normal population and was focused on individuals expressing interest in scientifically inclined
347
students and professionals. While the CAQ is a valid and reliable measure of creative
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achievement, our sample, comprised of mostly college students, have had fewer opportunities to
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express their potential due to their relatively young age and low professional status. The CAQ is
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always skewed in its distribution, with occasional extreme outliers. We chose to remove such
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outliers (+3 s.d.) although these individuals could represent true creative accomplishment.
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Removing high achievers therefore could have impacted our results. We re-ran the analysis
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with those 6 outliers included in the sample and found significantly decreased surface area
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in the posterior cingulate gyrus. However, to have 6 subjects drive the overall relationship
355
would not, in our opinion, represent the balance of the findings across the remaining 248
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subjects; therefore, we ultimately decided to remove them from the analysis. Future studies
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focused on such extreme outliers could be helpful in understanding brain organization in
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extremely high creative achievement. Finally, we failed to replicate the findings of both our
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previous study and that of another group, although we have provided several methodological
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reasons why the current results might differ. Future research will be necessary to support the
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relationships observed between brain structure and creative achievement. We would encourage
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researchers to use methods designed to parse cortical thickness, area, and volume (e.g.,
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FreeSurfer) as opposed to voxel intensities, the former of which, arguably, gets closer to
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biological variables of interest. We would further encourage researchers to include age, sex, total
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brain volume, and intellectual functioning (e.g., IQ). This last variable is particularly important
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to include as a covariate, given its significant relationship to variables of interest to creativity
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research (e.g., divergent thinking, CAQ), as well as established brain-IQ relationships which
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could potentially confound the variable of interest (R.E. Jung & Haier, 2007).
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