Planum Polare Research Articles

Structural alterations of the superior temporal gyrus in schizophrenia: Detailed subregional differences

BackgroundReduced gray matter volumes in the superior temporal gyrus (STG) have been reported in patients with schizophrenia. Such volumetric abnormalities might denote alterations in cortical thickness, surface area, local gyrification or all of these factors. The STG can be anatomically divided into five subregions using automatic parcellation in FreeSurfer: lateral aspect of the STG, anterior transverse temporal gyrus of Heschl gyrus (HG), planum polare (PP) of the STG, planum temporale (PT) of the STG and transverse temporal sulcus. MethodsWe acquired magnetic resonance imaging (MRI) 3T scans from 40 age- and sex-matched patients with schizophrenia and 40 healthy subjects, and the scans were automatically processed using FreeSurfer. General linear models were used to assess group differences in regional volumes and detailed thickness, surface area and local gyrification. ResultsAs expected, patients with schizophrenia had significantly smaller bilateral STG volumes than healthy subjects. Of the five subregions in the STG, patients with schizophrenia showed significantly and marginally reduced volumes in the lateral aspect of the STG and PT of the STG bilaterally compared with healthy subjects. The volumetric alteration in bilateral lateral STG was derived from both the cortical thickness and surface area but not local gyrification. There was no significant laterality of the alteration in the lateral STG between patients and controls and no correlation among the structures and clinical characteristics. ConclusionsThese findings suggest that of five anatomical subregions in the STG, the lateral STG is one of the most meaningful regions for brain pathophysiology in schizophrenia.

Altered Fronto-Temporal Functional Connectivity in Individuals at Ultra-High-Risk of Developing Psychosis.

BackgroundThe superior temporal gyrus (STG) is one of the key regions implicated in psychosis, given that abnormalities in this region are associated with an increased risk of conversion from an at-risk mental state to psychosis. However, inconsistent results regarding the functional connectivity strength of the STG have been reported, and the regional heterogeneous characteristics of the STG should be considered.MethodsTo investigate the distinctive functional connection of each subregion in the STG, we parcellated the STG of each hemisphere into three regions: the planum temporale, Heschl’s gyrus, and planum polare. Resting-state functional magnetic resonance imaging was obtained from 22 first-episode psychosis (FEP) patients, 41 individuals at ultra-high-risk for psychosis (UHR), and 47 demographically matched healthy controls.ResultsSignificant group differences (in seed-based connectivity) were demonstrated in the left planum temporale and from both the right and left Heschl’s gyrus seeds. From the left planum temporale seed, the FEP and UHR groups exhibited increased connectivity to the bilateral dorsolateral prefrontal cortex. In contrast, the FEP and UHR groups demonstrated decreased connectivity from the bilateral Heschl’s gyrus seeds to the dorsal anterior cingulate cortex. The enhanced connectivity between the left planum temporale and right dorsolateral prefrontal cortex was positively correlated with positive symptom severity in individuals at UHR (r = .34, p = .03).ConclusionsThese findings corroborate the fronto-temporal connectivity disruption hypothesis in schizophrenia by providing evidence supporting the altered fronto-temporal intrinsic functional connection at earlier stages of psychosis. Our data indicate that subregion-specific aberrant fronto-temporal interactions exist in the STG at the early stage of psychosis, thus suggesting that these aberrancies are the neural underpinning of proneness to psychosis.

Aberrant functional connectivity of resting state networks associated with trait anxiety

Trait anxiety, a personality dimension, has been characterized by functional consequences such as increased distractibility, attentional bias in favor of threat-related information and hyper-responsive amygdala. However, literature on the association between resting state brain functional connectivity, as studied using resting state functional magnetic resonance imaging (rs-fMRI), and reported anxiety levels in the sub-clinical population is limited. In the present study, we employed rs-fMRI to investigate the possible alterations in the functional integrity of Resting State Networks (RSNs) associated with trait anxiety of the healthy subjects (15 high anxious and 14 low anxious). The rs-fMRI data was analyzed using independent component analysis and a dual regression approach that was applied on 12 RSNs that were identified using FSL. High anxious subjects showed significantly reduced functional connectivity in regions of the default mode network (posterior cingulate gyrus, middle and superior temporal gyrus, planum polare, supramarginal gyrus, temporal pole, angular gyrus and lateral occipital gyrus) which has been suggested to be involved in episodic memory, theory of mind, self-evaluation, and introspection, and perceptual systems including medial visual network, auditory network and another network involving temporal, parieto-occipital and frontal regions. Reduction in resting state connectivity in regions of the perceptual networks might underlie the perceptual, attentional and working memory deficits associated with trait anxiety. To our knowledge, this is the first study to relate trait anxiety to resting state connectivity using independent component analysis.

Structural alterations of brain grey and white matter in early deaf adults

Functional and structural brain alterations in the absence of the auditory input have been described, but the observed structural brain changes in the deaf are not uniform. Some of the previous researchers focused only on the auditory areas, while others investigated the whole brain or other selected regions of interest. Majority of studies revealed decreased white matter (WM) volume or altered WM microstructure and preserved grey matter (GM) structure of the auditory areas in the deaf. However, preserved WM and increased or decreased GM volume of the auditory areas in the deaf have also been reported. Several structural alterations in the deaf were found also outside the auditory areas, but these regions differ between the studies. The observed differences between the studies could be due to the use of different single-analysis techniques, or the diverse population sample and its size, or possibly due to the usage of hearing aids by some participating deaf subjects. To overcome the aforementioned limitations four different image-processing techniques were used to investigate changes in the brain morphology of prelingually deaf adults who have never used hearing aids. GM and WM volume of the Heschl's gyrus (HG) were measured using manual volumetry, while whole brain GM volume, thickness and surface area were assessed by voxel-based morphometry (VBM) and surface-based analysis. The microstructural properties of the WM were evaluated by diffusion tensor imaging (DTI). The data were compared between 14 congenitally deaf adults and 14 sex- and age-matched normal hearing controls. Manual volumetry revealed preserved GM volume of the bilateral HG and significantly decreased WM volume of the left HG in the deaf. VBM showed increased cerebellar GM volume in the deaf, while no statistically significant differences were observed in the GM thickness or surface area between the groups. The results of the DTI analysis showed WM microstructural alterations between the groups in the bilateral auditory areas, including the superior temporal gyrus, the HG, the planum temporale and the planum polare, which were more extensive in the right hemisphere. Fractional anisotropy (FA) was significantly reduced in the right and axial diffusivity (AD) in the left auditory areas in the deaf. FA and AD were significantly reduced also in several other brain areas outside the auditory cortex in the deaf.The use of four different methods used in our study, although showing changes that are not directly related, provides additional information and supports the conclusion that in prelingually deaf subjects structural alterations are present both in the auditory areas and elsewhere. Our results support the findings of those studies showing that early deafness results in decreased WM volume and microstructural WM alterations in the auditory areas. As we observed WM microstructural alteration also in several other areas and increased GM volume in the cerebellum in the deaf, we can conclude that early deafness results in widespread structural brain changes. These probably reflect atrophy or degradation as well as compensatory cross-modal reorganisation in the absence of the auditory input and the use of the sign language.

Music listening engages specific cortical regions within the temporal lobes: Differences between musicians and non-musicians

Music and speech are two of the most relevant and common sounds in the human environment. Perceiving and processing these two complex acoustical signals rely on a hierarchical functional network distributed throughout several brain regions within and beyond the auditory cortices. Given their similarities, the neural bases for processing these two complex sounds overlap to a certain degree, but particular brain regions may show selectivity for one or the other acoustic category, which we aimed to identify. We examined 53 subjects (28 of them professional musicians) by functional magnetic resonance imaging (fMRI), using a paradigm designed to identify regions showing increased activity in response to different types of musical stimuli, compared to different types of complex sounds, such as speech and non-linguistic vocalizations. We found a region in the anterior portion of the superior temporal gyrus (aSTG) (planum polare) that showed preferential activity in response to musical stimuli and was present in all our subjects, regardless of musical training, and invariant across different musical instruments (violin, piano or synthetic piano). Our data show that this cortical region is preferentially involved in processing musical, as compared to other complex sounds, suggesting a functional role as a second-order relay, possibly integrating acoustic characteristics intrinsic to music (e.g., melody extraction). Moreover, we assessed whether musical experience modulates the response of cortical regions involved in music processing and found evidence of functional differences between musicians and non-musicians during music listening. In particular, bilateral activation of the planum polare was more prevalent, but not exclusive, in musicians than non-musicians, and activation of the right posterior portion of the superior temporal gyrus (planum temporale) differed between groups. Our results provide evidence of functional specialization for music processing in specific regions of the auditory cortex and show domain-specific functional differences possibly correlated with musicianship.

Brain imaging the activity associated with pitch intervals in a melody

Early attempts to locate brain regions involved in pitch processing employed sequences of notes with no pitch, fixed pitch, and melodic pitch. They revealed a region of Heschl’s gyrus lateral to primary auditory cortex where sequences with pitch produced more activity than noise, and regions where melody produced more activation than fixed pitch (in planum polare and the superior temporal sulcus). Subsequent research has focused on the fixed pitch region in Heschl’s gyrus and the degree to which the activity is pitch specific. Recently, MEG techniques have been developed to compare the responses to sequences of notes as they occur within bars of music, and to separate current sources associated with attention to melody. This paper illustrates how the techniques can be used to investigate the hierarchy of pitch and melody processing as it occurs in four bar phrases with brass instruments. The experiments show that a given note elicits a larger response when it is part of a melody and the increment is associated with a source beyond auditory cortex. The paper shows how we might track the responses to orchestral instrument sounds presented in a musical context as they proceed through auditory cortex and beyond the temporal lobes.

Cortical Grey Matter and Subcortical White Matter Brain Microstructural Changes in Schizophrenia Are Localised and Age Independent: A Case-Control Diffusion Tensor Imaging Study

It is still unknown whether the structural brain impairments that characterize schizophrenia (SZ) worsen during the lifetime. Here, we aimed to describe age-related microstructural brain changes in cortical grey matter and subcortical white matter of patients affected by SZ. In this diffusion tensor imaging study, we included 69 patients diagnosed with SZ and 69 healthy control (HC) subjects, age and gender matched. We carried out analyses of covariance, with diagnosis as fixed factor and brain diffusion-related parameters as dependent variables, and controlled for the effect of education. White matter fractional anisotropy decreased in the entire age range spanned (18–65 years) in both SZ and HC and was significantly lower in younger patients with SZ, with no interaction (age by diagnosis) effect in fiber tracts including corpus callosum, corona radiata, thalamic radiations and external capsule. Also, grey matter mean diffusivity increased in the entire age range in both SZ and HC and was significantly higher in younger patients, with no age by diagnosis interaction in the left frontal operculum cortex, left insula and left planum polare and in the right temporal pole and right intracalcarine cortex. In individuals with SZ we found that localized brain cortical and white matter subcortical microstructural impairments appear early in life but do not worsen in the 18–65 year age range.

From Vivaldi to Beatles and back: Predicting lateralized brain responses to music

We aimed at predicting the temporal evolution of brain activity in naturalistic music listening conditions using a combination of neuroimaging and acoustic feature extraction. Participants were scanned using functional Magnetic Resonance Imaging (fMRI) while listening to two musical medleys, including pieces from various genres with and without lyrics. Regression models were built to predict voxel-wise brain activations which were then tested in a cross-validation setting in order to evaluate the robustness of the hence created models across stimuli. To further assess the generalizability of the models we extended the cross-validation procedure by including another dataset, which comprised continuous fMRI responses of musically trained participants to an Argentinean tango. Individual models for the two musical medleys revealed that activations in several areas in the brain belonging to the auditory, limbic, and motor regions could be predicted. Notably, activations in the medial orbitofrontal region and the anterior cingulate cortex, relevant for self-referential appraisal and aesthetic judgments, could be predicted successfully. Cross-validation across musical stimuli and participant pools helped identify a region of the right superior temporal gyrus, encompassing the planum polare and the Heschl's gyrus, as the core structure that processed complex acoustic features of musical pieces from various genres, with or without lyrics. Models based on purely instrumental music were able to predict activation in the bilateral auditory cortices, parietal, somatosensory, and left hemispheric primary and supplementary motor areas. The presence of lyrics on the other hand weakened the prediction of activations in the left superior temporal gyrus. Our results suggest spontaneous emotion-related processing during naturalistic listening to music and provide supportive evidence for the hemispheric specialization for categorical sounds with realistic stimuli. We herewith introduce a powerful means to predict brain responses to music, speech, or soundscapes across a large variety of contexts.

Cortical Surface Area and Cortical Thickness Demonstrate Differential Structural Asymmetry in Auditory-Related Areas of the Human Cortex

This investigation provides an analysis of structural asymmetries in 5 anatomically defined regions (Heschl's gyrus, HG; Heschl's sulcus, HS; planum temporale, PT; planum polare, PP; superior temporal gyrus, STG) within the human auditory-related cortex. Volumetric 3-dimensional T1-weighted magnetic resonance imaging scans were collected from 104 participants (52 males). Cortical volume (CV), cortical thickness (CT), and cortical surface area (CSA) were calculated based on individual scans of these anatomical traits. This investigation demonstrates a leftward asymmetry for CV and CSA that is observed in the HG, STG, and PT regions. As regards CT, we note a rightward asymmetry in the HG and HS. A correlation analysis of asymmetry indices between measurements for distinct regions of interest (ROIs) yields significant correlations between CT and CV in 4 of 5 ROIs (HG, HS, PT, and STG). Significant correlation values between CSA and CV are observed for all 5 ROIs. The findings suggest that auditory-related cortical areas demonstrate larger leftward asymmetry with respect to the CSA, while a clear rightward asymmetry with respect to CT is salient in both the primary and the secondary auditory cortex only. In addition, we propose that CV is not an ideal neuromarker for anatomical measurements. CT and CSA should be considered independent traits of anatomical asymmetries in the auditory-related cortex.

Diminished Whole-brain but Enhanced Peri-sylvian Connectivity in Absolute Pitch Musicians

Several anatomical studies have identified specific anatomical features within the peri-sylvian brain system of absolute pitch (AP) musicians. In this study we used graph theoretical analysis of cortical thickness covariations (as indirect indicator of connectivity) to examine whether AP musicians differ from relative pitch musicians and nonmusicians in small-world network characteristics. We measured "local connectedness" (local clustering = γ), "global efficiency of information transfer" (path length = λ), "small-worldness" (σ = γ/λ), and "degree" centrality as measures of connectivity. Although all groups demonstrated typical small-world features, AP musicians showed significant small-world alterations. "Degree" as a measure of interconnectedness was globally significantly decreased in AP musicians. These differences let us suggest that AP musicians demonstrate diminished neural integration (less connections) among distant brain regions. In addition, AP musicians demonstrated significantly increased local connectivity in peri-sylvian language areas of which the planum temporale, planum polare, Heschl's gyrus, lateral aspect of the superior temporal gyrus, STS, pars triangularis, and pars opercularis were hub regions. All of these brain areas are known to be involved in higher-order auditory processing, working or semantic memory processes. Taken together, whereas AP musicians demonstrate decreased global interconnectedness, the local connectedness in peri-sylvian brain areas is significantly higher than for relative pitch musicians and nonmusicians.

A Corticostriatal Neural System Enhances Auditory Perception through Temporal Context Processing

The temporal context of an acoustic signal can greatly influence its perception. The present study investigated the neural correlates underlying perceptual facilitation by regular temporal contexts in humans. Participants listened to temporally regular (periodic) or temporally irregular (nonperiodic) sequences of tones while performing an intensity discrimination task. Participants performed significantly better on intensity discrimination during periodic than nonperiodic tone sequences. There was greater activation in the putamen for periodic than nonperiodic sequences. Conversely, there was greater activation in bilateral primary and secondary auditory cortices (planum polare and planum temporale) for nonperiodic than periodic sequences. Across individuals, greater putamen activation correlated with lesser auditory cortical activation in both right and left hemispheres. These findings suggest that temporal regularity is detected in the putamen, and that such detection facilitates temporal-lobe cortical processing associated with superior auditory perception. Thus, this study reveals a corticostriatal system associated with contextual facilitation for auditory perception through temporal regularity processing.

Reducing the Effects of Background Noise During Auditory Functional Magnetic Resonance Imaging of Speech Processing: Qualitative and Quantitative Comparisons Between Two Image Acquisition Schemes and Noise Cancellation

The intense sound generated during functional magnetic resonance imaging (fMRI) complicates studies of speech and hearing. This experiment evaluated the benefits of using active noise cancellation (ANC), which attenuates the level of the scanner sound at the participant's ear by up to 35 dB around the peak at 600 Hz. Speech and narrowband noise were presented at a low sound level to 8 listeners during fMRI using 2 common scanning protocols: short ("continuous") and long ("sparse") temporal schemes. Three outcome measures were acquired simultaneously during fMRI: ratings of listening quality, discrimination performance, and brain activity. Subjective ratings and discrimination performance were significantly improved by ANC and sparse acquisition. Sparse acquisition was the more robust method for detecting auditory cortical activity. ANC reduced some of the "extra-auditory" activity that might be associated with the effort required for perceptual discrimination in a noisy environment and also offered small improvements for detecting activity within Heschl's gyrus and planum polare. For the scanning protocols evaluated here, the sparse temporal scheme was the more preferable for detecting sound-evoked activity. In addition, ANC ensures that listening difficulty is determined more by the chosen stimulus parameters and less by the adverse testing environment.

Evidence for early specialized processing of speech formant information in anterior and posterior human auditory cortex

Many speech sounds, such as vowels, exhibit a characteristic pattern of spectral peaks, referred to as formants, the frequency positions of which depend both on the phonological identity of the sound (e.g. vowel type) and on the vocal-tract length of the speaker. This study investigates the processing of formant information relating to vowel type and vocal-tract length in human auditory cortex by measuring electroencephalographic (EEG) responses to synthetic unvoiced vowels and spectrally matched noises. The results revealed specific sensitivity to vowel formant information in both anterior (planum polare) and posterior (planum temporale) regions of auditory cortex. The vowel-specific responses in these two areas appeared to have different temporal dynamics; the anterior source produced a sustained response for as long as the incoming sound was a vowel, whereas the posterior source responded transiently when the sound changed from a noise to a vowel, or when there was a change in vowel type. Moreover, the posterior source appeared to be largely invariant to changes in vocal-tract length. The current findings indicate that the initial extraction of vowel type from formant information is complete by the level of non-primary auditory cortex, suggesting that speech-specific processing may involve primary auditory cortex, or even subcortical structures. This challenges the view that specific sensitivity to speech emerges only beyond unimodal auditory cortex.

A follow-up MRI study of the superior temporal subregions in schizotypal disorder and first-episode schizophrenia

While longitudinal magnetic resonance imaging (MRI) studies have demonstrated progressive gray matter reduction of the superior temporal gyrus (STG) during the early phases of schizophrenia, it remains unknown whether patients with schizotypal features exhibit similar STG changes. In this study, longitudinal MRI data were obtained from 18 patients with first-episode schizophrenia, 13 patients with schizotypal disorder, and 20 healthy controls. The volumes of the STG and its subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), rostral STG, and caudal STG] were measured on baseline and follow-up (mean: 2.7 years) scans and were compared across groups. At the baseline, both the schizophrenia and schizotypal patients had smaller left PT and left caudal STG than the controls. In a longitudinal comparison, the schizophrenia patients showed significant gray matter reduction of the STG over time (left: − 2.8%/year; right: − 1.5%/year) compared with the schizotypal patients (left: − 0.6%/year; right: − 0.3%/year) and controls (left: 0.0%/year; right: − 0.1%/year) without a prominent effect of subregion or type of antipsychotic (typical/atypical). In the schizophrenia patients, greater annual volume reductions of the left PP and right PT were correlated with less improvement of positive psychotic symptoms. A higher cumulative dose of antipsychotics during follow-up in schizophrenia was significantly correlated with less severe gray matter reductions in the left PT and bilateral caudal STG. Our findings suggest that the left posterior STG subregions are commonly reduced in diseases of the schizophrenia spectrum; whereas, schizophrenia patients exhibit further progressive STG changes associated with overt psychosis in the early years of the illness.

Progressive structural brain changes in schizophrenia

Several important progressive brain changes occur in schizophrenia. Continuous progressive brain tissue decreases and lateral ventricular volume increases in chronically ill patients, up to at least 20 years after their first symptoms. The total duration of psychosis may be negatively associated with the grey matter volume change, and positively associated with the volume change of each of the lateral ventricles and the third ventricle. There are progressive frontal changes in males with adolescent-onset psychosis. Ultra high-risk patients who subsequently develop psychosis and first-episode psychosis patients develop significant grey matter reduction in the planum polare, planum temporale and caudal region; a progressive process in the superior temporal gyrus may precede the first expression of florid psychosis. The rate of decline in the sizes of the putamen and corpus callosum is greater in patients with a poor outcome compared to those with a good-outcome. In addition to describing these phenomena, their potential causes are discussed.

MICROSURGICAL ANATOMY OF THE TEMPORAL LOBE

We present observations of the anatomy of the sylvian fissure region and their clinical application in neuroimaging, microsurgery for middle cerebral artery aneurysms and insular lesions, frontobasal resections, and epilepsy surgery. Sixty adult cadaveric hemispheres and 12 adult cadaveric heads were studied after perfusion of the arteries and veins with colored latex. The anatomic information was applied in more than 200 microsurgeries in and around the sylvian fissure region in the past 15 years. The sylvian fissure extends from the basal to the lateral surface of the brain and presents 2 compartments on each surface, 1 superficial (temporal stem and its ramii) and 1 deep (anterior and lateral operculoinsular compartments). The temporal operculum is in opposition to the frontal and parietal opercula (planum polare versus inferior frontal and precentral gyri, Heschl's versus postcentral gyri, planum temporale versus supramarginal gyrus). The inferior frontal, precentral, and postcentral gyri cover the anterior, middle, and posterior thirds of the lateral surface of the insula, respectively. The pars triangularis covers the apex of the insula, located immediately distal to the genu of the middle cerebral artery. The clinical application of the anatomic information presented in this article is in angiography, middle cerebral artery aneurysm surgery, insular resection, frontobasal resection, and amygdalohippocampectomy, and hemispherotomy. The anatomic relationships of the sylvian fissure region can be helpful in preoperative planning and can serve as reliable intraoperative navigation landmarks in microsurgery involving that region.

An MRI study of the superior temporal subregions in patients with current and past major depression

The superior temporal gyrus (STG), especially its lateral portion, and temporal pole (TP) both play a central role in emotional processing, but it remains largely unknown whether patients with major depressive disorder (MDD) exhibit morphologic changes in these regions. We delineated the STG subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), rostral STG, and caudal STG] and TP using magnetic resonance imaging in 29 currently depressed patients (mean age=32.5 years, 7 males), 27 remitted depressed patients (mean age=35.1 years, 9 males), and 33 age- and gender-matched healthy control subjects (mean age=34.0 years, 12 males). Both current and remitted MDD patients showed a significant volume reduction of the left PT and bilateral caudal STG as compared with healthy controls. The TP volume did not differ between the groups. The right PT volume was negatively correlated with total score on the Beck Depression Inventory in the MDD patients as a whole. Medication, presence of melancholia, and comorbidity with anxiety disorders did not affect the TP and STG volumes. These findings suggest that the volume reduction of the STG, but not the TP, may represent enduring brain changes in MDD even after recovery from depression, but right STG volume may also be related to the severity of depressive symptoms.

Dichotic pitch activates pitch processing centre in Heschl's gyrus

Although several neuroimaging studies have reported pitch-evoked activations at the lateral end of Heschl's gyrus, it is still under debate whether these findings truly represent activity in relation to the perception of pitch or merely stimulus-related features of pitch-evoking sounds. We investigated this issue in a functional magnetic resonance imaging (fMRI) experiment using pure tones in noise and dichotic pitch sequences, which either contained a melody or a fixed pitch. Dichotic pitch evokes a sensation of pitch only in binaural listening conditions, while the monaural signal cannot be distinguished from random noise. Our data show similar neural activations for both tones in noise and dichotic pitch, which are perceptually similar, but physically different. Pitch-related activation was found at the lateral end of Heschl's gyrus in both hemispheres, providing new evidence for a general involvement of this region in pitch processing. In line with prior studies, we found melody-related activation in Planum temporale and Planum polare, but not in primary auditory areas. These results support the view of a general representation of pitch in auditory cortex, irrespective of the physical attributes of the pitch-evoking sound.

Gray matter reduction of the superior temporal gyrus in patients with established bipolar I disorder

BackgroundFunctional abnormalities of the superior temporal gyrus (STG) have been implicated in the pathophysiology of bipolar disorder, but magnetic resonance imaging (MRI) studies of this region have yielded inconsistent findings. MethodWe used MRI to examine the volumes of the STG and its gray matter subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), and lateral STG (rostral and caudal regions)] in 26 patients with established bipolar I disorder (8 males and 18 females, mean age=38.4years) and 24 age and gender-matched healthy controls (7 males and 17 females, mean age=38.7years). ResultsBipolar patients had significantly smaller volumes of the PT and caudal STG compared with controls in the left hemisphere. The STG white matter volume did not differ between the groups. There was no association between the STG volume and number of manic/depressive episodes, family history, or clinical subtype (i.e., psychotic and nonpsychotic), but daily dosage of lithium treatment at the time of scanning was positively correlated with right PP and right rostral STG volumes. LimitationsEntire clinical data (e.g., lifetime medication, symptomatology) were not available. ConclusionsThese findings implicate a role for the STG gray matter, especially its left posterior regions, in the neurobiology of bipolar disorder. Our findings may also support the notion of lithium-induced gray matter expansion.

An MRI study of the superior temporal subregions in first-episode patients with various psychotic disorders

Morphologic abnormalities of the superior temporal gyrus (STG) have been reported in schizophrenia, but have not been extensively studied in other psychotic disorders such as affective psychosis. In the present study, magnetic resonance imaging was used to examine the volumes of the STG and its subregions [planum polare (PP), Heschl gyrus (HG), planum temporale (PT), rostral STG, and caudal STG] in 162 first-episode patients with various psychotic disorders [46 schizophrenia (31 schizophrenia and 15 schizoaffective disorder), 57 schizophreniform disorder, 34 affective psychosis, and 25 other psychoses] and 62 age- and sex-matched healthy controls. The first-episode schizophrenia patients had significantly less gray matter in HG, PT, and caudal STG bilaterally compared with all other groups, but there was no difference between the controls and affective psychosis, schizophreniform disorder, or other psychoses for any STG subregion. The STG white matter volume did not differ between groups. Our findings indicate that morphologic abnormalities of the STG gray matter are specific to schizophrenia among various psychotic disorders, implicating its role in the underlying pathophysiology of schizophrenia.