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This study was to examine cortical thickness in drug naive, first episode schizophrenia patients, and to explore its relationship with serum levels of brain-derived neurotrophic factor (BDNF). Forty-five drug naive schizophrenia patients and 28 healthy controls were enrolled in the study. Freesurfer was used to parcellate cortical regions, and vertex-wise group analysis was used for whole brain cortical thickness. The clusters for the brain regions that demonstrated group differences were extracted, and the mean values of thickness were calculated. Serum levels of BDNF were measured using enzyme-linked immunosorbent assay (ELISA). After controlling for age and gender, significantly thinner cortical thickness was found in left insula and superior temporal gyrus in the patient group compared with the healthy control group (HC group) (p's < 0.001). Lower serum levels of BDNF were also found in the patient group compared with the HC group (p = 0.001). Correlation analysis showed a significant positive relationship between thickness of left insula and serum levels of BDNF within the HC group (r = 0.396, p = 0.037) but there was no such relationship within the patient group (r = 0.035, p = 0.819). Cortical thinning is present in drug naive, first episode schizophrenia patients, indicating neurodevelopmental abnormalities at the onset of schizophrenia. Left insula might be an imaging biomarker in detecting the impaired protective role of neurotrophic factor for the brain development in schizophrenia.

Every month, numerous publications appear that include neuroanatomic volumetric observations. The current and past literature that includes volumetric measurements is vast, but variable with respect to specific species, structures, and subject characteristics (such as gender, age, pathology, etc.). In this report we introduce the Internet Brain Volume Database (IBVD), www.nitrc.org/projects/ibvd , a site devoted to facilitating access to and utilization of neuroanatomic volumetric observations as published in the literature. We review the design and functionality of the site. The IBVD is the first database dedicated to integrating, exposing and sharing brain volumetric observations across species and disease. It offers valuable functionality for quality assurance assessment of results as well as support for meta-analysis across large segments of the published literature that are obscured from traditional text-based search engines.

Background: Regional prefrontal cortex gray matter reductions have been identified in schizophrenia, likely reflecting a combination of genetic vulnerability and disease effects. Few morphometric studies to date have examined regional prefrontal abnormalities in non-psychotic biological relatives who have not passed through the age range of peak risk for onset of psychosis. We conducted a region-of-interest morphometric study of prefrontal subregions in adolescent and young adult relatives of schizophrenia patients. Methods: Twenty-seven familial high-risk (FHR) first-degree relatives of schizophrenia patients and forty-eight control subjects without a family history of psychosis (ages 13–28) underwent high-resolution magnetic resonance imaging at 1.5 Tesla. The prefrontal cortex was parcellated into polar, dorsolateral, ventrolateral, ventromedial and orbital subregions. The Chapman scales measured subpsychotic symptoms. General linear models examined associations of prefrontal subregion volumes with familial risk and subpsychotic symptoms. Results: FHR subjects had significantly reduced bilateral ventromedial prefrontal and frontal pole gray matter volumes compared with controls. Ventromedial volume was significantly negatively correlated with magical ideation and anhedonia scores in FHR subjects. Conclusions: Selective, regional prefrontal gray matter reductions may differentially mark genetic vulnerability and early symptom processes among non-psychotic young adults at familial risk for schizophrenia.

Corpus callosum (CC) area abnormalities have been reported in magnetic resonance imaging (MRI) studies of adults and youths with bipolar disorder (BPD), suggesting interhemispheric communication may be abnormal in BPD and may be present early in the course of illness and affect normal neuromaturation of this structure throughout the lifecycle. Neuroimaging scans from 44 youths with DSM-IV BPD and 22 healthy controls (HC) were analyzed using cross-sectional area measurements and a novel method of volumetric parcellation. Univariate analyses of variance were conducted on CC subregions using both volume and traditional area measurements. Youths with BPD had smaller middle and posterior callosal regions, and reduced typical age-related increases in CC size. The cross-sectional area and novel volumetric methodologies resulted in similar findings. Future longitudinal assessments of CC development would track the evolution of callosal abnormalities in youths with BPD and allow exploration of the functional significance of these findings.

A significant number of children with bipolar disorder (BP) have co-morbid attention-deficit/hyperactivity disorder (ADHD). It is unknown if these children have neuroimaging findings unique to their co-morbid presentation, or if their brain findings are similar to children diagnosed with BP alone.Fifty three children with Diagnostic and Statistical Manual of Mental Disorders, 4(th) edition (DSM-IV) BP (23 with ADHD, 30 without), 29 healthy controls (HC), and 23 children with ADHD, similar in sex and age, had magnetic resonance imaging (MRI) scans on a 1.5T GE scanner. Volumetric assessments were performed for basal ganglia and limbic subcortical structures.Youths with ADHD had smaller caudate and putamen volumes compared to both BP groups and they had moderately smaller total amygdala volumes compared to the other three groups. Youths with BP + ADHD had moderately larger nucleus accumbens volumes than HC, and females in both BP groups had smaller hippocampal volumes compared to ADHD and HC. No differences were found between the BP and BP + ADHD groups.These data suggest that morphometric subcortical volumes in youths with BP + ADHD are more similar to those in youths with BP. They do not share subcortical neuroanatomic correlates with the ADHD group. These findings suggest that BP + ADHD is a subtype of pediatric BP rather than severe ADHD.

SummaryThe structural effects of cocaine on neural systems mediating cognition and motivation are not well known. By comparing the thickness of neocortical and paralimbic brain regions between cocaine-dependent and matched control subjects, we found that four of 18 a priori regions involved with executive regulation of reward and attention were significantly thinner in addicts. Correlations were significant between thinner prefrontal cortex and reduced keypresses during judgment and decision making of relative preference in addicts, suggesting one basis for restricted behavioral repertoires in drug dependence. Reduced effortful attention performance in addicts also correlated with thinner paralimbic cortices. Some thickness differences in addicts were correlated with cocaine use independent of nicotine and alcohol, but addicts also showed diminished thickness heterogeneity and altered hemispheric thickness asymmetry. These observations suggest that brain structure abnormalities in addicts are related in part to drug use and in part to predisposition toward addiction.

Amygdala volume has been associated with drug craving in cocaine addicts, and amygdala volume reduction is observed in some alcohol-dependent subjects. This study sought an association in alcohol-dependent subjects between volumes of reward-related brain regions, alcohol craving, and the risk of relapse.Besides alcohol craving, the authors assessed amygdala, hippocampus, and ventral striatum volumes in 51 alcohol-dependent subjects and 52 age- and education-matched healthy comparison subjects after detoxification. After imaging and clinical assessment, patients were followed for 6 months and alcohol intake was recorded.Alcohol-dependent subjects showed reduced amygdala, hippocampus, and ventral striatum volumes and reported stronger craving in relation to healthy comparison subjects. However, only amygdala volume and craving differentiated between subsequent relapsers and abstainers. A significant decrease of amygdala volume in alcohol-dependent subjects was associated with increased alcohol craving before imaging and an increased alcohol intake during the 6-month follow-up period.These findings suggest a relationship between amygdala volume reduction, alcohol craving, and prospective relapse into alcohol consumption.

Recent anatomical studies have found that cortical neurons are mainly preserved during the aging process while myelin damage and even axonal loss is prominent throughout the forebrain. We used diffusion tensor imaging (DT-MRI) to evaluate the hypothesis that during the process of normal aging, white matter changes preferentially affect the integrity of long corticocortical association fiber tracts, specifically the superior longitudinal fasciculus II and the cingulum bundle. This would disrupt communication between the frontal lobes and other forebrain regions leading to cognitive impairments. We analyzed DT-MRI datasets from seven young and seven elderly behaviorally characterized rhesus monkeys, creating fractional anisotropy (FA) maps of the brain. Significant age-related reductions in mean FA values were found for the superior longitudinal fasciculus II and the cingulum bundle, as well as the anterior corpus callosum. Comparison of these FA reductions with behavioral measures demonstrated a statistically significant linear relationship between regional FA and performance on a test of executive function. These findings support the hypothesis that alterations to the integrity of these long association pathways connecting the frontal lobe with other forebrain regions contribute to cognitive impairments in normal aging. To our knowledge this is the first investigation reporting such alterations in the aging monkey.

The insula is anatomically situated to be critically involved in many bio-behavioral functions impaired in schizophrenia. Furthermore, its total volume has been shown to be reduced in schizophrenia. In the present study, we tested the hypothesis that in schizophrenia it is the anterior insular lobule (aINS(lbl)) rather than the posterior insular lobule (pINS(lbl)) that is smaller, given that limbic system abnormalities are central in schizophrenia and that the affiliations of the limbic system are principally with the anterior insular lobule. We used T1-weighted high resolution magnetic resonance imaging (MRI) to measure the cortical volume of the left and right anterior and posterior insular subdivisions. The subjects included a sample of healthy community controls (N=40) and chronic patients with DSM-III-R schizophrenia (N=41). We correlated insula volumes with positive and negative symptoms. We found that the total aINS(lbl), and the left aINS(lbl) in particular, were significantly volumetrically smaller in schizophrenia compared to controls, and significantly correlated with bizarre behavior. Given that the anterior insular lobule offers anatomic features that allow for MRI-based morphometric analysis, namely its central and circular sulci, this brain structure provides a useful model to test hypotheses regarding genotype-phenotype relationships in schizophrenia using the anterior insular lobule as a candidate endophenotype.

Pediatric bipolar disorder (BPD) is a severe psychiatric illness with significant morbidity whose pathophysiology is largely still unknown. The morbidity associated with this disorder is driven, in part, by the child’s inability to modulate affect and cognition; those affected by the disorder have a diminished ability to control the intensity of a response to the environment and the ease of recovery from the response. For example, even in euthymic individuals with BPD, there are enduring impairments in attention, executive functioning, processing speed, and in working and verbal declarative memory that lead to difficulties in daily life (1). In addition, individuals who are genetically at risk for developing BPD have deficits in verbal declarative memory, selective and sustained attention, and in working memory, suggesting that these domains may serve as cognitive endophenotypic markers of the disorder that in turn could implicate areas of pathophysiology in the brain (1). For example, these domains of cognitive functioning are largely under the control of the cerebral cortex and are highly heritable (2–4). Therefore, in order to contribute to a deeper understanding of the neurobiological correlates that underlie the dysfunction associated with the disorder (5), it is critical to study the cerebral cortex, where brain operations occur that govern cognitive abilities (6). Taken collectively, published neuroimaging (functional, biochemical, and structural) studies indicate that there may be cortical abnormalities in adults and children with BPD (7–12). To understand more fully the differences in the cortex seen in children with BPD, it is critical to assess the lobes of cortical gray matter (GM) and the gyri of each lobe, as different regions of the cortex subserve different cognitive functions. For example, the frontal lobe (FL) is involved in cognition, memory, sensory processing, planning and initiation of voluntary movements, language production, and integration of cognition and affect. The temporal lobe (TL) is integral for auditory processing, language comprehension, semantic memory processing, visual perception, and sensory integration (13). The parietal lobe (PL) is involved in processing tactile and proprioceptive information, language comprehension, speech, writing, and aspects of spatial orientation and perception. The occipital lobe (OL) is involved in visual functions (13). To our knowledge a detailed anatomical assessment of the entire cerebral cortex, using structural magnetic resonance imaging (MRI), has not been carried out in studies in adults with BPD, nor has it been carried out in child studies. Of particular importance is the need to assess the cortex in children with BPD, given that their brains are relatively free from factors known to affect the brain, such as lengthy medication exposure, substance abuse, and electroconvulsive therapies (14). To our knowledge, this is the first structural neuroimaging study to fully assess the entire cortical GM and subsequently the gyri of the lobes of the cortex in pediatric BPD. Based on prior studies (neuroimaging and neuropsychological), we set out to assess expected alterations in cortical volumes, in pediatric BPD, to determine if these youth might show a specific pattern of cortical GM deficits. Given the data from the prior neuroimaging studies (in both children and adults), we hypothesized that children with BPD would show cortical GM deficits, particularly in sections of the FL, similar to adults with the disorder.

Youths with bipolar disorder are ideal for studying illness pathophysiology given their early presentation, lack of extended treatment, and high genetic loading. Adult bipolar disorder MRI studies have focused increasingly on limbic structures and the thalamus because of their role in mood and cognition. On the basis of adult studies, the authors hypothesized a priori that youths with bipolar disorder would have amygdalar, hippocampal, and thalamic volume abnormalities.Forty-three youths 6-16 years of age with DSM-IV bipolar disorder (23 male, 20 female) and 20 healthy comparison subjects (12 male, eight female) similar in age and sex underwent structured and clinical interviews, neurological examination, and cognitive testing. Differences in limbic and thalamic brain volumes, on the logarithmic scale, were tested using a two-way (diagnosis and sex) univariate analysis of variance, with total cerebral volume and age controlled.The subjects with bipolar disorder had smaller hippocampal volumes. Further analysis revealed that this effect was driven predominantly by the female bipolar disorder subjects. In addition, both male and female youths with bipolar disorder had significantly smaller cerebral volumes. No significant hemispheric effects were seen.These findings support the hypothesis that the limbic system, in particular the hippocampus, may be involved in the pathophysiology of pediatric bipolar disorder. While this report may represent the largest MRI study of pediatric bipolar disorder to date, more work is needed to confirm these findings and to determine if they are unique to pediatric bipolar disorder.

This study examined activation levels in the left (L) supplementary motor area (SMA) and the right (R) SMA (separately), and activation in nine R perisylvian language homologues during overt, propositional speech in chronic nonfluent aphasia patients. Previous functional imaging studies with a variety of chronic aphasia patients have reported activation in these regions during different language tasks, however, overt propositional speech has not been examined. In the present research, four nonfluent aphasia patients were studied during overt elicited propositional speech at 4-9 years post-single L hemisphere stroke, which spared the SMA. The dynamic susceptibility contrast (DSC) method of functional MRI was used to calculate relative cerebral blood volume (relCBV) for cortical regions of interest (ROIs) during the first-pass bolus of gadolinium during two conditions: (1) pattern (silent viewing of checkerboard patterns) and (2) story (overt, elicited propositional speech describing sequential pictures, which formed a story). During the story condition, controls had significantly higher relCBV in L SMA than in R SMA; aphasics, however, had significantly higher relCBV in R SMA than in L SMA. During the pattern condition, no significant differences were observed between the L SMA and the R SMA for either controls or aphasics. In addition, aphasics had significantly higher relCBV in the R sensorimotor mouth during story than pattern. This R sensorimotor mouth relCBV was also significantly higher in aphasics than controls during story, and the two groups did not differ during pattern. The overall mean relCBV for the nine R perisylvian ROIs was significantly higher for aphasics than controls during both story and pattern. These results suggest that poor modulation, including possible over-activation of R sensorimotor mouth and other R perisylvian language homologues may underlie in part, the hesitant, poorly articulated, agrammatic speech associated with nonfluent aphasia.

Diffusion tensor magnetic resonance imaging (DT-MRI) assesses the integrity of white matter (WM) tracts in the brain. Children with bipolar disorder (BPD) may have WM abnormalities that precede illness onset. To more fully examine this possibility, we scanned children with DSM-IV BPD and compared them to healthy peers and children at risk for BPD (AR-BPD), defined as having a first-degree relative with the disorder.Ten children with BPD, eight healthy controls (HC), and seven AR-BPD, similar in age, had MRI scans on a 1.5 Tesla GE scanner, including a standard DT-MRI sequence (T2-EPI) with 25 axial slices. Fractional anisotropy (FA) values were compared between groups to determine regions of significant difference (p0.05).Compared to HC, children with BPD had decreased FA in right and left superior frontal tracts, including the superior longitudinal fasciculus I (SLF I) and the cingulate-paracingulate WM (CG-PAC(WM)). In addition, the BPD group had reduced FA in left orbital frontal WM and the right corpus callosum body. Compared to AR-BPD, children with BPD showed reduced FA in the right and left CG-PAC(WM). Both the BPD and AR-BPD groups showed reduced FA relative to HC in bilateral SLF I.The bilateral SLF I finding in both the BPD and AR-BPD groups may represent a trait-based marker or endophenotype of the disorder. The finding of decreased FA in the right and left CG-PAC(WM) in children with BPD compared to the other two groups may represent a disease-state related finding.

Objective: The limbic structures in early-onset schizophrenia-spectrum illness (SZ) and bipolar disorder (BPD) were studied to discern patterns associated with diagnosis and sex. Methods: Thirty-five youths with DSM-IV BPD without psychosis, 19 with BPD with psychosis, 20 with SZ, and 29 healthy controls (HC), similar in age (6-17 years) and sex, underwent structured and clinical interviews, neurological examination, and cognitive testing. Structural magnetic resonance images (MRIs) were acquired on a 1.5 Tesla, General Electric Signa Scanner. Differences in subcortical brain volumes, including the amygdala and hippocampus, were evaluated using two-way (diagnosis, sex) univariate analyses covarying for total cerebral volume and age. Results: Youth with SZ and BPD showed no differences in amygdala and hippocampal volumes. However, boys with SZ had smallest left amygdala and girls with BPD had the smallest left hippocampal volumes. In exploratory analyses, SZ showed reduced thalamic volumes bilaterally and both BPD groups had larger right nucleus accumbens (NA) volumes relative to HC. Conclusion: There were no limbic volumetric differences between BPD and SZ. However, there were diagnosis-by-sex interactions in the amygdala and hippocampus, structures that are rich in sex hormone receptors. In addition, smaller thalamus was associated with SZ while larger right NA volumes were most related to BPD. This study underscores the importance of assessing diagnostic effects and sex effects on the brain in future studies and provides evidence that boys and girls with SZ and BPD may have differential patterns of neuropathology associated with disease expression.

Attention-deficit/hyperactivity disorder (ADHD) is hypothesized to be due, in part, to structural defects in brain networks influencing cognitive, affective, and motor behaviors. Although the current literature on fiber tracts is limited in ADHD, gray matter abnormalities suggest that white matter (WM) connections may be altered selectively in neural systems. A prior study (Ashtari et al. 2005), using diffusion tensor magnetic resonance imaging (DT-MRI), showed alterations within the frontal and cerebellar WM in children and adolescents with ADHD. In this study of adults with childhood ADHD, we hypothesized that fiber pathways subserving attention and executive functions (EFs) would be altered. To this end, the cingulum bundle (CB) and superior longitudinal fascicle II (SLF II) were investigated in vivo in 12 adults with childhood ADHD and 17 demographically comparable unaffected controls using DT-MRI. Relative to controls, the fractional anisotropy (FA) values were significantly smaller in both regions of interest in the right hemisphere, in contrast to a control region (the fornix), indicating an alteration of anatomical connections within the attention and EF cerebral systems in adults with childhood ADHD. The demonstration of FA abnormalities in the CB and SLF II in adults with childhood ADHD provides further support for persistent structural abnormalities into adulthood.

Our objective was to test for differences between subjects with obsessive-compulsive disorder (OCD) and healthy controls with respect to white matter architecture within the cingulum bundle (CB) and anterior limb of the internal capsule (ALIC). We studied eight subjects with active OCD and 10 matched healthy controls using diffusion tensor magnetic resonance imaging (DT-MRI) at 1.5 T (Tesla). Fractional anisotropy (FA) was evaluated in both CB and ALIC. Both voxelwise and region-of-interest methods of analysis were employed. Within both the left CB and the left ALIC, subjects with OCD exhibited significantly greater FA than healthy controls. In the right CB, subjects with OCD exhibited significantly decreased FA versus healthy control subjects. Additionally, the OCD group exhibited abnormal asymmetry (left > right) of FA in the CB. These results provide preliminary evidence for abnormal architecture within the CB and ALIC in OCD. FA differences in these areas are consistent with the presence of abnormal connections between the nodes linked by these tracts. This could explain why surgically severing these tracts is therapeutic. Additional studies are needed to replicate these findings and to clarify their pathological and clinical significance.

Background Basal ganglia (BG) enlargement has been found in studies of adults with bipolar disorder (BPD), while the few studies of BPD youths have had mixed findings. The BG (caudate, putamen, globus pallidus, nucleus accumbens) is interconnected with limbic and prefrontal cortical structures and therefore may be implicated in BPD. Methods Sixty-eight youths (46 with BPD, 22 healthy controls) received neurological and psychiatric assessment, semi-structured interviews, and neuropsychological testing, followed by anatomic magnetic resonance imaging on a 1.5 Tesla scanner. After image segmentation, log BG volumes and asymmetry indices were analyzed using MANOVAs controlling for the effects of cerebral volume, age, sex, and diagnosis. These omnibus tests were followed by univariate linear regression models of each BG structure. Results Youths with BPD had a trend for larger right nucleus accumbens (NA) volumes ( p = 0.089). There were no significant group asymmetry differences, nor volume differences in the caudate, putamen, and globus pallidus. When analyzed separately by pubertal status, the prepubertal group had significantly larger total NA ( p = 0.035) versus healthy controls, while the pubertal group did not show significant differences in the NA versus healthy controls. Limitations The size of the control group is relatively small, possibly limiting our power to detect significant group differences. The inter-rater reliability for the NA is not as strong as the other structures; the finding of volume differences in this structure is preliminary and warrants replication. Conclusions Youths with BPD had larger right NA volumes; this enlargement was most pronounced in the prepubertal group. The differences between these findings and those seen in adult BPD imply a neurodevelopmental phenomenon.

Background Limited knowledge exists regarding the neurobiology of trichotillomania (TTM). Cerebellum (CBM) volumes were explored, given its role in complex, coordinated motor sequences. Methods Morphometric magnetic resonance imaging (MRI) scans were obtained for 14 female subjects with DSM-IV diagnoses of TTM and 12 age-, education-, and gender-matched normal control (NC) participants. Parcellation was performed utilizing a recently developed methodology to measure subterritory volumes of the CBM. Regions were defined based on knowledge of the structural and functional subunits of the CBM. Results As predicted, significant group differences were reported for CBM raw cortical volumes (p = .008) that survived correction for total brain volume (TBV; p = .037) and head circumference (HC; p = .011). A priori and post hoc group raw volume comparisons for CBM subterritories and functional clusters revealed many significant differences. However, most differences failed to withstand correction for total CBM volumes (TCV). Smaller volumes were consistently reported for the TTM versus NC cohorts. Total Massachusetts General Hospital Hair Pulling Scale (MGHHPS) scores were significantly inversely correlated with left primary sensorimotor cluster volumes (p = .008), with smaller volumes associated with more severe TTM symptoms. Conclusions These findings implicate the CBM in the neurobiology of TTM, with reduced subterritory volumes reported for the TTM versus NC groups.

Background Acupuncture stimulation elicits deqi, a composite of unique sensations that is essential for clinical efficacy according to traditional Chinese medicine (TCM). There is lack of adequate experimental data to indicate what sensations comprise deqi, their prevalence and intensity, their relationship to acupoints, how they compare with conventional somatosensory or noxious response. The objective of this study is to provide scientific evidence on these issues and to characterize the nature of the deqi phenomenon in terms of the prevalence of sensations as well as the uniqueness of the sensations underlying the deqi experience. Methods Manual acupuncture was performed at LI4, ST36 and LV3 on the extremities in randomized order during fMRI in 42 acupuncture naïve healthy adult volunteers. Non-invasive tactile stimulation was delivered to the acupoints by gentle tapping with a von Frey monofilament prior to acupuncture to serve as a sensory control. At the end of each procedure, the subject was asked if each of the sensations listed in a questionnaire or any other sensations occurred during stimulation, and if present to rate its intensity on a numerical scale of 1–10. Statistical analysis including paired t-test, analysis of variance, Spearman's correlation and Fisher's exact test were performed to compare responses between acupuncture and sensory stimulation. Results The deqi response was elicited in 71% of the acupuncture procedures compared with 24% for tactile stimulation when thresholded at a minimum total score of 3 for all the sensations. The frequency and intensity of individual sensations were significantly higher in acupuncture. Among the sensations typically associated with deqi, aching, soreness and pressure were most common, followed by tingling, numbness, dull pain, heaviness, warmth, fullness and coolness. Sharp pain of brief duration that occurred in occasional subjects was regarded as inadvertent noxious stimulation. The most significant differences in the deqi sensations between acupuncture and tactile stimulation control were observed with aching, soreness, pressure and dull pain. Consistent with its prominent role in TCM, LI4 showed the most prominent response, the largest number of sensations as well as the most marked difference in the frequency and intensity of aching, soreness and dull pain between acupuncture and tactile stimulation control. Interestingly, the dull pain generally preceded or occurred in the absence of sharp pain in contrast to reports in the pain literature. An approach to summarize a sensation profile, called the deqi composite, is proposed and applied to explain differences in deqi among acupoints. Conclusion The complex pattern of sensations in the deqi response suggests involvement of a wide spectrum of myelinated and unmyelinated nerve fibers, particularly the slower conducting fibers in the tendinomuscular layers. The study provides scientific data on the characteristics of the 'deqi' response in acupuncture and its association with distinct nerve fibers. The findings are clinically relevant and consistent with modern concepts in neurophysiology. They can provide a foundation for future studies on the deqi phenomenon.