Planum Temporale Volume Research Articles

Neuromagnetic evidence for hippocampal modulation of auditory processing

The hippocampus is well known to be involved in memory, as well as in perceptual processing. To date, the electrophysiological process by which unilateral hippocampal lesions, such as hippocampal sclerosis (HS), modulate the auditory processing remains unknown. Auditory-evoked magnetic fields (AEFs) are valuable for evaluating auditory functions, because M100, a major component of AEFs, originates from auditory areas. Therefore, AEFs of mesial temporal lobe epilepsy (mTLE, n=17) with unilateral HS were compared with those of healthy (HC, n=17) and disease controls (n=9), thereby determining whether AEFs were indicative of hippocampal influences on the auditory processing. Monaural tone-burst stimuli were presented for each side, followed by analysis of M100 and a previously less characterized exogenous component (M400: 300–500ms). The frequency of acceptable M100 dipoles was significantly decreased in the HS side. Beam-forming-based source localization analysis also showed decreased activity of the auditory area, which corresponded to the inadequately estimated dipoles. M400 was found to be related to the medial temporal structure on the HS side. Volumetric analysis was also performed, focusing on the auditory-related areas (planum temporale, Heschl's gyrus, and superior temporal gyrus), as well as the hippocampus. M100 amplitudes positively correlated with hippocampal and planum temporale volumes in the HC group, whereas they negatively correlated with Heschl's gyrus volume in the mTLE group. Interestingly, significantly enhanced M400 component was observed in the HS side of the mTLE patients. In addition, the M400 component positively correlated with Heschl's gyrus volume and tended to positively correlate with disease duration. M400 was markedly diminished after hippocampal resection. Although volumetric analysis showed decreased hippocampal volume in the HS side, the planum temporale and Heschl's gyrus, the two major sources of M100, were preserved. These results suggested that HS significantly influenced AEFs. Therefore, we concluded that the hippocampus modulates auditory processing differently under normal conditions and in HS.

Putting Research into Practice for Autism Spectrum Disorder

Putting Research into Practice for Autism Spectrum Disorder

Planum temporale asymmetry to the right hemisphere in first-episode schizophrenia

In schizophrenia patients reduced cerebral asymmetry is an important finding and this may reflect a disturbance in cortical development. We investigated planum temporale (PT) volume and asymmetry in 23 first-episode schizophrenia patients compared to healthy controls and found for the first time an in vivo volume asymmetry of PT to the right hemisphere.

Auditory cortical volumes and musical ability in Williams syndrome

Individuals with Williams syndrome (WS) have been shown to have atypical morphology in the auditory cortex, an area associated with aspects of musicality. Some individuals with WS have demonstrated specific musical abilities, despite intellectual delays. Primary auditory cortex and planum temporale volumes were manually segmented in 25 individuals with WS and 25 control participants, and the participants also underwent testing of musical abilities. Left and right planum temporale volumes were significantly larger in the participants with WS than in controls, with no significant difference noted between groups in planum temporale asymmetry or primary auditory cortical volumes. Left planum temporale volume was significantly increased in a subgroup of the participants with WS who demonstrated specific musical strengths, as compared to the remaining WS participants, and was highly correlated with scores on a musical task. These findings suggest that differences in musical ability within WS may be in part associated with variability in the left auditory cortical region, providing further evidence of cognitive and neuroanatomical heterogeneity within this syndrome.

Reduced Laterality as a Trait Marker ofSchizophrenia—Evidence from Structural and Functional Neuroimaging

Laterality is a characteristic principle of the organization of the brain systems for language, and reduced hemispheric asymmetry has been considered a risk factor for schizophrenia. Here we sought support for the risk factor hypothesis by investigating whether reduced asymmetry of temporal lobe structure and function is also present in unaffected relatives. Sixteen schizophrenia patients, 16 age-matched first-degree relatives, and 15 healthy controls underwent high-resolution three-dimensional anatomical imaging and functional magnetic resonance imaging during auditory stimulation. Both the overall auditory cortex and planum temporale volumes and the lateralization to the left hemisphere were markedly reduced in patients. The decrease of lateralization correlated with increased severity of symptoms. In addition, both the overall functional activation in response to auditory stimulation and its asymmetry were reduced in the patients. Relatives had intermediate values between patients and controls on both structural and functional measures. This study provides added support for the idea that reduced hemispheric asymmetry is a biological risk factor for schizophrenia.

Age-Related Changes in the Anatomy of Language Regions in Autism Spectrum Disorder

Impairments in language and communication are core features of autism spectrum disorder (ASD). The anatomy of critical language areas has been studied in ASD with inconsistent findings. We used MRI to measure gray matter volume and asymmetry of Heschl's gyrus, planum temporale, pars triangularis, and pars opercularis in 40 children and adolescents with ASD and 40 typically developing individuals, each divided into younger (7-11 years) and older (12-19 years) cohorts. The older group had larger left planum temporale volume and stronger leftward asymmetry than the younger group, regardless of diagnosis. The pars triangularis and opercularis together were larger in ASD than controls. Correlations between frontal language areas with language and symptom severity scores were significant in younger ASD children. Results suggest similar developmental changes in planum temporale anatomy in both groups, but group differences in pars triangularis and opercularis that may be related to language abilities and autism symptom severity.

Reduced planum temporale volume and delusional behaviour in patients with schizophrenia

The structural abnormality of planum temporale (PT), a part of the superior temporal heteromodal association cortex involved in auditory and language processing, has been implicated in the pathophysiology of schizophrenia. However, its relationship to clinical manifestations remains unclear. Magnetic resonance images were obtained from 17 right-handed Japanese men with schizophrenia and from 22 age-, handedness-, and parental socioeconomic-status-matched healthy Japanese men in order to manually evaluate grey matter volumes of Heschl's gyrus (HG) and PT. Psychiatric symptoms were assessed using positive and negative syndrome scale among the patients. Compared with healthy participants, patients with schizophrenia were associated with a statistically significant PT grey matter volume reduction without left or right lateralization, whereas HG volume was preserved. Smaller right PT volume was significantly correlated with more severe delusional behaviour in the patients. Previous investigations have focused on smaller-than-normal left PT in the pathophysiology of schizophrenia; however, the present results suggest a possible role of the right PT, which is involved in social cognition such as understanding the intentions of others, in the production of psychotic experiences in patients with schizophrenia.

Volumetric analysis of a specific language region – the planum temporale

Planum temporale volumes were determined for 42 control children (ages 4.2–15.7 years) using magnetic resonance imaging. The mean left planum temporale volume was 2729 mm 3 (SD = 567) and the mean right planum temporale volume was 2758 mm 3 (SD = 546). No significant hemispheric asymmetry was demonstrated. Analysis of co-variance (ANCOVA) showed that the absolute and proportional planum temporale volumes were not significantly associated with age or gender. We also demonstrated a reproducible method for planum temporale volume measurement by acquiring images in the coronal plane and then visualising the sagittal plane to improve accuracy for the posterior border.

Planum Temporale Volume in Children and Adolescents with Autism

Previous research has revealed a lack of planum temporale (PT) asymmetry in adults with autism. This finding is now extended to children and adolescents with the disorder. MRI scans were obtained from 12 children with autism and 12 gender, handedness and age-matched comparison participants. The volume of gray matter in the PT and Heschl's gyrus (HG) in both hemispheres was measured. PT volume was larger in the left hemisphere than in the right in the comparison, but not the autism group. This specifically reflected reduced volume of the left PT in the autism group. There were noted differences in the overall morphological appearance of the right Sylvian fissure in the autism group, but no volumetric difference in the right PT. No differences in HG volumes were observed between the two groups. Lack of PT asymmetry may suggest an early neurodevelopmental disturbance in autism.

Abnormal association between reduced magnetic mismatch field to speech sounds and smaller left planum temporale volume in schizophrenia

Schizophrenia is associated with language-related dysfunction. A previous study [Schizophr. Res. 59 (2003c) 159] has shown that this abnormality is present at the level of automatic discrimination of change in speech sounds, as revealed by magnetoencephalographic recording of auditory mismatch field in response to across-category change in vowels. Here, we investigated the neuroanatomical substrate for this physiological abnormality. Thirteen patients with schizophrenia and 19 matched control subjects were examined using magnetoencephalography (MEG) and high-resolution magnetic resonance imaging (MRI) to evaluate both mismatch field strengths in response to change between vowel /a/ and /o/, and gray matter volumes of Heschl's gyrus (HG) and planum temporale (PT). The magnetic global field power of mismatch response to change in phonemes showed a bilateral reduction in patients with schizophrenia. The gray matter volume of left planum temporale, but not right planum temporale or bilateral Heschl's gyrus, was significantly smaller in patients with schizophrenia compared with that in control subjects. Furthermore, the phonetic mismatch strength in the left hemisphere was significantly correlated with left planum temporale gray matter volume in patients with schizophrenia only. These results suggest that structural abnormalities of the planum temporale may underlie the functional abnormalities of fundamental language-related processing in schizophrenia.

Smaller left hemisphere planum temporale in adults with autistic disorder

The structure of the planum temporale is often disturbed in disorders with associated communication problems, particularly in auditory and language processing areas in the brain. We hypothesized that people with autism would have reduced left hemisphere volumes in the planum temporale, a language related brain structure. We performed magnetic resonance imaging scans of 15 adults with autistic disorder and 15 comparison subjects, and measured the volume of gray matter in the planum temporale and Heschl's gyrus (HG) in both hemispheres. Planum temporale volume reduced in the left hemisphere of the autism group ( P<0.003). No differences in HG volumes were observed between the two groups. The volume reduction seen in the left hemisphere of the autism group may suggest an early neurodevelopmental disturbance in autism that impacts language development.

Are auditory hallucinations the consequence of abnormal cerebral lateralization? A morphometric MRI study of the sylvian fissure and planum temporale

Background: Auditory verbal hallucinations (AVHs) are a characteristic feature of schizophrenia. Patients with schizophrenia have been found to have reduced volumes of a variety of brain structures as well as a reduction in right–left asymmetries, using postmortem and magnetic resonance imaging (MRI) measures. There is also evidence that patients with AVHs differ in these structural asymmetries, relative to those patients who do not hallucinate. The aim of this study was to examine whether patients with and without a prominent history of AVHs differ, both from each other and in comparison with normal subjects, in the asymmetry of the sylvian fissure (SF) and planum temporale (PT). Methods: We recruited 74 DSM-IV male patients with schizophrenia (on the basis of their AVH history) and 32 matched normal control subjects. Thirty patients had no history of AVHs and 44 had a strong definitive history of AVHs. The SF length and PT area and volume were measured on a three-dimensional MRI spoiled GRASS volume sequence. Absolute measures and laterality coefficients were calculated. Results: All groups had the normal leftward asymmetry in both the SF and PT. Planum temporale volume and surface area and SF length were all larger in the left hemisphere. There were no significant differences in any measures between the two patient groups or between schizophrenic patients and control subjects. Greater leftward asymmetry of the SF correlated with hallucinations and thought disorder within the prominent hallucinator group. An association was found between handedness and brain size, but this did not interact with diagnosis. Conclusions: The results of this study do not confirm reports, based on smaller samples, of reduced structural asymmetries of either the SF or PT in schizophrenia, nor do they indicate a specific relationship to a propensity to experience AVHs. A modest correlation between leftward asymmetry of the SF and some positive symptomatology was found.

44. Reduced left Heschl’s gyrus volume in schizotypal personality disorder

Schizotypal personality disorder (SPD) shares the same genetic diathesis as the schizophrenia spectrum disorders, yet persons with SPD are not psychotic and generally have not been prescribed neuroleptics. Therefore, they may represent an ideal group to study the underlying structural abnormalities in the spectrum disorders. Previously we showed SPD subjects to have enlarged CSF volumes, parahippocampal aysmmetry, and reduced left superior temporal gyrus (STG) gray matter volumes compared with normal control subjects. The STG consists anatomically of the anterior pole, Heschl’s gyrus (primary auditory sensory cortex) and planum temporale (auditory unimodal association cortex). In order to better define this STG abnormality, we examined Heschl’s gyrus and planum temporale in an extended group of subjects. Subjects: SPD subjects were all right-handed males (N = 24) and age-matched within 3 years to the comparison subjects (N = 23)), with no difference in IQ, years of education or parental socio-economic status. SPD subjects did have lower socioeconomic status. Image processing: The STG was manually drawn on the acquired coronal images consisting of 124 slices. To correct for the effects of head tilt, the images were realigned and resegmented to form a new set of images with over 200 slices and isotropic voxels. The drawings were edited as necessary and the boundaries were extended to their anterior and posterior most extent with high interrator reliability (intraclass r > 0.99). The effect of brain volume on region size was accounted for using a regression procedure. The resultant residual volume for left Heschl’s gyrus was not normally distributed and Mann-Whitney U statistics were used. There was no difference in volume of the total intracranial contents. The SPD subjects showed a 21% reduction in left Heschl’s gyrus volume, but no difference in right Heschl or planum temporale volume or Heschl or planum asymmetry. These findings suggest that the reduced left STG finding may be, in part, due to the volume reduction of Heschl’s gyrus. This is intriguing as Heschl’s gyrus participates in early processing of auditory stimuli (tones) and is consistent with the finding of abnormal P300 amplitude in a similar group of SPD subjects.

45. Gender differences in aging effect on the 5-HTlA receptor with [11C-carbonyl]way100635 PET

difference in volume of the total intracranial contents. The SPD subjects showed a 21% reduction in left Heschl’s gyrus volume, but no difference in right Heschl or planum temporale volume or Heschl or planum asymmetry. These findings suggest that the reduced left STG finding may be, in part, due to the volume reduction of Heschl’s gyrus. This is intriguing as Heschl’s gyrus participates in early processing of auditory stimuli (tones) and is consistent with the finding of abnormal P300 amplitude in a similar group of SPD subjects.

Left planum temporale volume reduction in schizophrenia.

The planum temporale, located on the posterior and superior surface of the temporal lobe, is a brain region thought to be a biological substrate of language and possibly implicated in the pathophysiology of schizophrenia. To investigate further the role of planum temporale abnormalities in schizophrenia, we measured gray matter volume underlying the planum temporale from high spatial resolution magnetic resonance imaging techniques. Sixteen male patients with chronic schizophrenia and 16 control subjects were matched for age, sex, handedness, and parental socioeconomic status. Magnetic resonance imaging images were obtained from a 1.5-T magnet. Gray matter volume was significantly reduced in the left planum temporale (28.2%) in schizophrenic patients compared with normal controls. Schizophrenic patients showed a reversal of the left greater than right planum temporale asymmetry found in normal controls. Heschl's gyrus (primary auditory cortex) showed no differences between the left and right sides in either group. Of note, the Suspiciousness/Persecution subscale score of the Positive and Negative Syndrome Scale was associated with reduced left planum temporale volume in schizophrenic patients. Patients with schizophrenia have reduced left planum temporale gray matter and a reversal of planum temporale asymmetry, which may underlie an impairment in language processing and symptoms of suspiciousness or persecution characteristic of schizophrenia.

Small planum temporale volume in Down's syndrome: a volumetric MRI study.

Down's syndrome is associated with structural brain abnormalities and language deficits. The aim of this study was to investigate whether the superior temporal gyrus and the planum temporale, both parts of the anatomic substrate for language, are abnormal in Down's syndrome. The authors examined volumetric magnetic resonance imaging (MRI) measures of the superior temporal gyrus and the planum temporale for 17 community-dwelling patients with Down's syndrome and 17 matched healthy comparison subjects. For the subjects with Down's syndrome, the correlations of the superior temporal gyrus and planum temporale volumes with performance on tests of language function were examined. The planum temporale volume of the patients with Down's syndrome was smaller than that of the healthy subjects, even after differences in whole brain volume were controlled for. The volume of the superior temporal gyrus in the Down's syndrome patients was proportionally similar to that of the comparison group. For the subjects with Down's syndrome, neither superior temporal gyrus nor planum temporale volume was significantly correlated with performance on language tests after total brain volume was controlled for. In Down's syndrome, planum temporale volume may be selectively smaller than normal, although the effect of this volume deficit on language is not clear.