Moreover, reduced oxy-hemoglobin concentration change for the right PFC was significantly correlated with verbal communication deficits within the PDD group. The statistical results did not change when only IQ-matched high-functioning subjects ( N = 7) were included. While the number of words generated during the letter fluency task did not differ significantly between groups, the analysis of covariance including IQ as a confounding covariate showed that the PDD group was associated with bilateral reduction in oxy-hemoglobin concentration change as compared with the control group.
The difficulties with social reciprocity, communication, and restricted behaviors and interests that occur with PDD suggest that the syndrome affects a functionally diverse and widely distributed set of neural systems. It refers to individuals who do not meet the diagnostic criteria for any of the four other pervasive.Pervasive developmental disorder (PDD) is defined on the basis of a selected set of behavioral disturbances that more or less map onto specific functional systems of the brain. PDD-NOS can often be referred to as Atypical Autism. Serotonin reuptake inhibitors (SRIs), the primary drug treatment for patients with OCD, may reduce the repetitive. Results from recent studies suggest that the types of repetitive thoughts and behavior of adults with autism and those with obsessive-compulsive disorder (OCD) may be different. The present results may be also potentially useful for applying NIRS to clinical settings of child psychiatry.Signs and Symptoms of PDD-NOS Atypical or inappropriate social behavior Uneven skill development (motor, sensory, visual-spatial organizational, cognitive.Repetitive thoughts and behavior are considered integral and core components of autistic disorder.
In accordance with the latter investigation, a PET study reported reduced dopaminergic activity in the dorsomedial PFC of autistic children. Another line of studies have used “theory of mind” tasks to investigate medial PFC abnormalities in PDDs a pilot positron emission tomography (PET) study of adults with Asperger's disorder showed specific engagement of the medial PFC, except that the center of activation was displaced below and anterior in the patients compared with controls , while another PET study showed reduced dorsomedial PFC activation in adults with PDD. An fMRI study reported a variable and scattered representation along the lateral convexity of the frontal and parietal lobes during a visually cued motor sequencing task in adults with autism. An fMRI study showed that autistic adults had significantly less task-related activation in dorsolateral PFC in comparison with healthy adults during a spatial working memory task. A functional magnetic resonance imaging (fMRI) study using the embedded figure task showed reduced activation of PFC and greater activation of ventral occipitotemporal regions in adults with PDD.
To evaluate change in the prefrontal cortex using NIRS, the verbal fluency test has been often used for cognitive activation, since previous NIRS studies have used letter fluency test for cognitive activations, and showed displayable prefrontal activation during the verbal fluency task in healthy subjects . In addition the cost is much lower than other neuroimaging modalities and the set-up is very easy.Although NIRS enables the noninvasive clarification of brain functions in many psychiatric disorders, including schizophrenia, bipolar disorder, depression, dementia of Alzheimer type and post-traumatic stress disorder , , , , , , , NIRS has not yet been applied to examine subjects with PDD. The subject can be examined in a natural sitting position, without any surrounding noise or feeling of obstruction. Because NIRS is relatively insensitive to motion artifact, it can be applied to emotional activation that might cause some motion of the subjects. NIRS is a neuroimaging modality that is especially suitable for psychiatric patients, due to the following reasons. Recently, the development of near-infrared spectroscopy (NIRS) has enabled noninvasive and bedside measurement of regional cerebral blood volume (rCBV) in terms of the relative concentrations of oxyhemoglobin and deoxyhemoglobin.
We also predicted that decreased would be associated with severity of symptoms in the PDD group.The subjects were 10 adults with PDD (six men and four women 18–37 years old) and age- ( t = 0.543, p = 0.594) and gender- ( χ-square test: p = 0.121) matched healthy subjects (9 men and 1 woman 24–34 years old). Based on previous studies using other neuroimaging techniques that showed lateral prefrontal dysfunction during executive tasks in PDD, we predicted that the subjects with PDD would show lower prefrontal change than healthy subjects. Therefore we conducted an NIRS cognitive activation study, using letter fluency test, to verify PFC dysfunction in PDD.
In the control group, change showed a significant DiscussionTo our knowledge, this is the first NIRS study that evaluated prefrontal activation in individuals with PDD. PDD subjects were diagnosed according to DSM-IV criteria by two trained ResultsThe number of words generated during the letter fluency task showed no statistically significant differences between the groups (PDD group: mean 13.5, S.D.: 2.9 control group: mean 15.4, S.D.: 2.5 comparison: t = 1.56, p = 0.14).In the control group, rapidly increased immediately after the start of the task period, was maintained at the activated level during the task period, and decreased gradually after the task was finished. Healthy subjects were recruited from college students, hospital staff and their acquaintances.
Recently, near-infrared spectroscopy (NIRS) studies have investigated the association between frontotemporal functional abnormalities and suicidality in patients with mood disorders. MR was supported by a Postdoctoral fellowship from the Japan Society for the Promotion of Science (P 05234).Adults diagnosed with Autism spectrum disorder (ASD) are at high risk of experiencing suicidality compared with other clinical groups. However, this result is incongruent with an AcknowledgementsThis study was supported by Grants from the Ministry of Health, Labour and Welfare, Japan (to KK and NK), and in part by Grant-in-Aid for Scientific Research for Young Investigators (to YK) from the MEXT, Japan. Depressed prefrontal blood volume change in PDD during an executive task is congruent with fMRI studies which reported decreased activation in PFC during executive function tasks.
However, we found a significant positive correlation between the current suicide risk score and the time-course of prefrontal hemodynamic activation in the ASD group. We found no significant differences between the verbal fluency task-induced prefrontal hemodynamic responses in the ASD vs. In addition, we used Spearman's correlation analysis to identify the relationship between the time-course of prefrontal hemodynamic activation and the current suicide risk in patients with ASD. Here, we used 24-channel NIRS to examine the characteristics of prefrontal hemodynamic responses during a verbal fluency task in 20 adults with ASD and in age-, sex-, and intelligence quotient-matched healthy controls.
Some studies revealed altered functional connectivity, suggesting an inefficient information transfer between brain regions in ASD. The majority of these studies reported atypical brain activation in the prefrontal cortex, inferior frontal gyrus, middle and superior temporal gyrus. These studies investigated either brain activation using multiple tasks (e.g., face processing, joint attention and working memory) or functional organization under a resting-state condition in ASD. This article reviews thirty empirical studies, published in the past decade, that used fNIRS in individuals with ASD or in infants with a high risk of developing ASD. This method has several advantages over other functional neuroimaging techniques in studying brain functions in ASD, including portability, low cost, and availability in naturalistic settings. Functional near-infrared spectroscopy (fNIRS) is increasingly being used in this respect.
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