**** NEUROIMAGING/ ELECROPHYSIOLOGY in PSYCHOPATHOLOGY, NEUROBEHAVIORAL DYSF.
Neurocase. 2003 Aug;9(4):340-9.
Enhancing the sensitivity of a sustained attention task to frontal damage: convergent clinical and functional imaging evidence.
Manly T, Owen AM, McAvinue L, Datta A, Lewis GH, Scott SK,
Rorden C, Pickard J,
Despite frequent reports of poor concentration following traumatic brain injury, studies have generally failed to find disproportionate time-on-task decrements using vigilance measures in this patient group. Using a rather different definition, neuropsychological and functional imaging research has however linked sustained attention performance to right prefrontal function--a region likely to be compromised by such injuries. These studies have emphasised more transitory lapses of attention during dull and ostensibly unchallenging activities. Here, an existing attention measure was modified to reduce its apparent difficulty or 'challenge'. Compared with the standard task, its capacity to discriminate traumatically head-injured participants from a control group was significantly enhanced. Unlike existing functional imaging studies, that have compared a sustained attention task with a no-task control, in study 2 we used positron emission tomography to contrast the two levels of the same task. Significantly increased blood flow in the dorsolateral region of the right prefrontal cortex was associated with the low challenge condition. While the results are discussed in terms of a frontal system involved in the voluntary maintenance of performance under conditions of low stimulation, alternative accounts in terms of strategy application are considered.
Psychiatry Res. 2003 Jul 30;123(3):153-63.
Impulsivity and prefrontal hypometabolism in borderline personality disorder, Pages 153-163
Paul H. Soloff, Carolyn Cidis Meltzer, Carl Becker, Phil J. Greer, Thomas M. Kelly and Doreen Constantine
hypoperfusion and decreased glucose uptake in the prefrontal cortex (PFC) are
found in violent criminal offenders, murderers and aggressive psychiatric
patients. These abnormalities may be independent of diagnosis and associated
with impulsive-aggression as a personality trait. Impulsive-aggression is a
clinical characteristic of borderline personality disorder (BPD) where it is
associated with assaultive and suicidal behaviors. We conducted FDG-PET studies
in 13 non-depressed, impulsive female subjects with BPD and 9 healthy controls
to look for abnormalities in glucose metabolism in areas of the PFC associated
with regulation of impulsive behavior. Statistical Parametric Mapping-99 ( was
used to analyze the PET data with
Article in Press, Corrected Proof - Note to users
A voxel-based morphometric MRI study in female patients with borderline personality disorder
N. Rüscha, L. Tebartz van Elst, , a, P. Ludaeschera, M. Wilkeb, H. -J. Huppertzc, T. Thield, C. Schmahla, M. Bohusa, K. Lieba, B. Heßlingera, J. Hennigd and D. Eberta
Subtle prefrontal and limbic structural abnormalities have been reported in borderline personality disorder (BPD). In order to further validate the previously reported findings and to more precisely describe the nature of the structural change we performed a voxel-based morphometric (VBM) study in patients with BPD. Twenty female patients with BPD and 21 female healthy controls were investigated. High-resolution 3-D datasets were acquired and analyzed following an optimized protocol of VBM in the framework of statistical parametric mapping (SPM99). Gray matter volume loss was found in the left amygdala. No other differences in gray or white matter volume or density were found anywhere else in the brain. Our findings support the hypothesis that temporolimbic abnormalities play a role in the pathophysiology of BPD. Prefrontal structural alterations in BPD were not observed in this study.
Article in Press, Corrected Proof - Note to users
A disturbance of nonlinear interdependence in scalp EEG of subjects with first episode schizophrenia
M. Breakspear, , a, b, c, J. R. Terryd, K. J. Fristone, A. W. F. Harrisa, c, L. M. Williamsa, f, K. Browna, J. Brennang and E. Gordona, c
been proposed that schizophrenia arises through a disturbance of coupling
between large-scale cortical systems. This "disconnection hypothesis"
is tested by applying a measure of dynamical interdependence to scalp EEG data.
EEG data were collected from 40 subjects with a first episode of schizophrenia
and 40 matched healthy controls. An algorithm for the detection of dynamical
interdependence was applied to six pairs of bipolar electrodes in each subject.
The topographic organization of the interdependence was calculated and served
as the principle measure of cortical integration. The rate of occurrence of
dynamical interdependence did not statistically differ between subject groups at
any of the sites. However, the topography across the scalp was significantly
different between the two groups. Specifically, nonlinear interdependence
tended to occur in larger concurrent "clusters" across the scalp in
schizophrenia than in the healthy subjects. This disturbance was reflected most
strongly in left intrahemispheric coupling and did not differ significantly
according to symptoma
Article in Press, Corrected Proof - Note to users
Neuroanatomical correlates of selected executive functions in middle-aged and older adults: a prospective MRI study
Faith M. Gunning-
Neuroanatomical substrates of age-related differences in working memory and perseverative behavior were examined in a sample of healthy adults (50–81 years old). The participants, who were screened for history of neurological, psychiatric, and medical conditions known to be linked to poor cognitive performance, underwent magnetic resonance imaging (MRI) and were administered tests of working memory and perseveration. Regional brain volumes and the volume of white matter hyperintensities (WMH) were measured on magnetic resonance images. The analyses indicate that the volume of the prefrontal cortex (PFC) and the volume of white matter hyperintensities in the prefrontal region are independently associated with age-related increases in perseverative errors on the Wisconsin Card Sorting Test (WCST). When participants taking antihypertensive medication were excluded from the analysis, both the volume of the prefrontal cortex and the frontal white matter hyperintensities (FWMH) still predicted increases in perseveration. Neither reduced volume of the prefrontal cortex nor the FWMH volume was linked to age-associated declines in working memory. The volumes of the fusiform gyrus (FG) and the temporal white matter hyperintensities (TWMH) were unrelated to cognitive performanc
Volume 19, Issue 2 , June 2003, Pages 376-390
Attention as a characteristic of nonclinical dissociation: an event-related potential study
Michiel B. de Ruiter, , a, R. Hans Phafa, Dick J. Veltmanb, Albert Koka and Richard van Dyckb
Individual differences in dissociative style (which is generally considered a risk factor for dissociative pathology) were studied in a nonclinical sample. It was hypothesized that high-dissociative participants would show enhanced attentional abilities toward both relevant and irrelevant stimulus features. In the experiment, threatening and affectively neutral words were classified on their affective valence and the presence of the letter A. To facilitate the full deployment of dissociative abilities, a feature (i.e., negative valence) was included that would automatically attract attention but not interfere with the processing of the central feature. Both the behavioral measures (i.e., reaction time) and the central neural measures (i.e., event-related potentials) showed that the ability to direct attention to the central feature was enhanced in the high dissociators. The high dissociators, moreover, showed evidence of directing attention to both affective valence and the letter A in the letter detection task. It is concluded that dissociative style does not correspond to a damaged or disturbed function but to an enhanced ability to direct and divide attention.
Vol. 60 No. 8, August 2003
Gambling Urges in Pathological Gambling
A Functional Magnetic Resonance Imaging Study
Marc N. Potenza, MD, PhD; Marvin A. Steinberg, PhD; Pawel
Arch Gen Psychiatry. 2003;60:828-836.
Background Gambling urges in pathological gambling (PG) often immediately precede engagement in self-destructive gambling behavior. An improved understanding of the neural correlates of gambling urges in PG would advance our understanding of the brain mechanisms underlying PG and would help direct research into effective treatments. Methods Echoplanar functional magnetic resonance imaging was used to assess brain function during viewing of videotaped scenarios with gambling, happy, or sad content. Participants rated the quality and magnitude of their emotional and motivational responses. Results Men with PG (n = 10) reported mean ± SD greater gambling urges after viewing gambling scenarios vs control subjects (n = 11) (5.20 ± 3.43 vs 0.32 ± 0.60; 21,19 = 21.71; P<.001). The groups did not differ significantly in their subjective responses to the happy (P = .56) or sad (P = .81) videotapes. The most pronounced between-group differences in neural activities were observed during the initial period of viewing of the gambling scenarios: PG subjects displayed relatively decreased activity in frontal and orbitofrontal cortex, caudate/basal ganglia, and thalamus compared with controls. Distinct patterns of regional brain activity were observed in specific temporal epochs of videotape viewing. For example, differences localized to the ventral anterior cingulate during the final period of gambling videotape viewing, corresponding to the presentation of the most provocative gambling stimuli. Although group differences in brain activity were observed during viewing of the sad and happy scenarios, they were distinct from those corresponding to the gambling scenarios. Conclusions In men with PG, gambling cue presentation elicits gambling urges and leads to a temporally dynamic pattern of brain activity changes in frontal, paralimbic, and limbic brain structures. When viewing gambling cues, PG subjects demonstrate relatively decreased activity in brain regions implicated in impulse regulation compared with controls.
J Neurosci. 2003 Oct 22;23(29):9632-8.
Dissociable contributions of the human amygdala and orbitofrontal cortex to incentive motivation and goal selection.
Arana FS, Parkinson JA, Hinton E,
Theories of incentive motivation attempt to capture the way in which objects and events in the world can acquire high motivational value and drive behavior, even in the absence of a clear biological need. In addition, for an individual to select the most appropriate goal, the incentive values of competing desirable objects need to be defined and compared. The present study examined the neural substrates by which appetitive incentive value influences prospective goal selection, using positron emission tomographic neuroimaging in humans. Sated subjects were shown a series of restaurant menus that varied in incentive value, specifically tailored for each individual, and in half the trials, were asked to make a selection from the menu. The amygdala was activated by high-incentive menus regardless of whether a choice was required. Indeed, activity in this region varied as a function of individual subjective ratings of incentive value. In contrast, distinct regions of the orbitofrontal cortex were recruited both during incentive judgments and goal selection. Activity in the medial orbital cortex showed a greater response to high-incentive menus and when making a choice, with the latter activity also correlating with subjective ratings of difficulty. Lateral orbitofrontal activity was observed selectively when participants had to suppress responses to alternative desirable items to select their most preferred. Taken together, these data highlight the differential contribution of the amygdala and regions within the orbitofrontal cortex in a neural system underlying the selection of goals based on the prospective incentive value of stimuli, over and above homeostatic influences.
Quantitative spectral analysis of EEG in psychiatry
revisited: drawing signs out of numbers in a clinical setting, In Press,
Corrected Proof, Available online
P. Coutin-Churchman, Y. Añez, M. Uzcátegui, L. Alvarez, F. Vergara, L. Mendez and R. Fleitas
Objective: To evaluate the incidence, sensitivity and specificity of abnormal quantitative EEG (QEEG) measures in normal subjects and patients with mental disorders.
Methods: Normalized QEEG measures were blindly assessed in 67 normal human beings and 340 psychiatric patients. QEEG results were correlated to subject condition or diagnosis and magnetic resonance imaging (MRI) findings.
Results: QEEG was abnormal in 83% of patients, and 12% of normal subjects. The most frequent abnormality was a decrease in slow (delta and/or theta) bands, either alone, with beta increase, or with alpha decrease, followed by increase in beta band. No normal subject showed delta and/or theta decrease. Slow band decrease was more frequent in depression and mental disorders due to general medical condition, alcohol and drug dependence. However, no pattern was specific of any entity, and patients within the same diagnostic may present different patterns. Delta-theta decrease was correlated with cortical atrophy as seen in MRI. Beta increase was correlated with psychoactive medication. No association was found between any other QEEG pattern and MRI abnormalities, or medication. Conclusions: Decrease in the delta and theta bands of the QEEG can be regarded as a specific sign of brain dysfunction, and is correlated with cortical atrophy. However, this sign, as other QEEG abnormal patterns, can be found in many different disorders and none of them can be considered as pathognomonic of any specific disorder.
Significance: This work attempted to circumvent the alleged lack of Class I evidence of QEEG utility in the study of psychiatric patients by means of a prospective, blinded study, searching for specific signs of physiopathology in individual patients.
Psychiatry Res. 2003 Jul 30;123(3):165-70
Targeted prefrontal cortical activation with bifrontal ECT
Hal Blumenfeld, Kelly A. McNally,
The anatomical brain regions involved in the therapeutic and adverse actions of electroconvulsive therapy (ECT) are unknown. Previous studies suggest that bifrontal vs. bitemporal ECT differ in therapeutic efficacy and cognitive side effects. We therefore performed cerebral blood flow (CBF) imaging during bitemporal vs. bifrontal ECT-induced seizures to identify regions crucial for the differences between these treatments. Patients with major depression, undergoing bitemporal or bifrontal ECT, were studied. Ictal–interictal SPECT images were analyzed with statistical parametric mapping for bitemporal (n=11 image pairs in 8 patients) and bifrontal (n=4 image pairs in 2 patients) ECT-induced seizures to identify regions of ictal CBF changes. Bifrontal ECT was found to cause increases in CBF in prefrontal and anterior cingulate regions. Bitemporal ECT, however, caused CBF increases in the lateral frontal cortex and in the anterior temporal lobes. In bifrontal ECT, a greater increase in prefrontal activation, while sparing the temporal lobes, may result in a better therapeutic response and fewer adverse effects on memory than bitemporal ECT.
Brain. 2003 Aug 22 [Epub ahead of print].
Conventional and magnetization transfer MRI predictors of clinical multiple sclerosis evolution: a medium-term follow-up study.
Rovaris M, Agosta F, Sormani MP, Inglese M, Martinelli V, Comi G, Filippi M.
Neuroimaging Research Unit, Department of Neuroscience, Scientific Institute and University Ospedale San Raffaele, via Olgettina, 60, 20132 Milan, Italy.
The correlation between conventional MRI lesion load accumulation and multiple sclerosis clinical evolution is only modest. The assessment of brain parenchymal volume and of its changes over time may provide adjunctive MRI markers reflecting the more disabling aspects of multiple sclerosis pathology. Magnetization transfer (MT) MRI is sensitive to 'occult' multiple sclerosis-related brain damage and might also contribute to overcome the clinical/MRI paradox. In this study, we assessed the value of conventional and MT MRI-derived metrics in predicting the medium-term clinical evolution of patients with different multiple sclerosis phenotypes. We studied 73 patients, with relapsing-remitting multiple sclerosis (n = 34), secondary progressive multiple sclerosis (n = 19) and clinically isolated syndromes suggestive of multiple sclerosis (n = 20), and 16 healthy subjects. Brain dual-echo, T1-weighted (only in patients) and MT MRI scans were obtained at baseline and after 12 months. T2-hyperintense and T1-hypointense lesion volumes, normalized brain volume and average lesion MT ratio (MTR) were measured. MTR histograms from the whole brain tissue were also obtained. Clinical multiple sclerosis evolution and neurological disability were re-assessed in all patients after a median follow-up of 4.5 years. A multivariate analysis was performed to establish which clinical and MRI-derived variables were significant predictors of neurological deterioration at the end of the study period. At the end of follow-up, 34 patients showed significant neurological deterioration. The final multivariable model included average brain MTR percentage change after one year [P = 0.02, odds ratio (OR) = 0.86] and baseline T2-hyperintense lesion volume (P = 0.04, OR=1.04) as independent predictors of medium-term disability accumulation (r(2) = 0.23). In this cohort of patients, abnormal values of average brain MTR changes showed a relatively high specificity (76.9%) and positive predictive value (59.1%) for Expanded Disability Status Scale score deterioration in individual cases. In patients with multiple sclerosis, a comprehensive estimation of the short-term changes of both conventional and MT MRI-detectable lesion burden might provide useful prognostic information for the medium-term clinical disease evolution.
Volume 34, 2003, 39-53
Quantitative EEG and the Frye and Daubert Standards of Admissibility
The 70-year-old Frye standards of “general acceptance” were replaced by the Supreme Court’s 1993 Daubert criteria of the scientific method, which established the standards for admissibility of evidence in Federal Court. The four Daubert criteria were: 1- Hypothesis testing, 2- Estimates of error rates, 3- Peer reviewed publication and 4- General acceptance (Daubert v. Merrell Dow Pharmaceuticals, 61 U.S.L.W 4805 (U.S. June 29, 1993)). The present paper starts with the Daubert four factors and then matches them, step by step, to the scientific peer reviewed literature of quantitative EEG (QEEG) in relation to different clinical evaluations. This process shows how the peer reviewed science of the Digital EEG and the Quantitative EEG (QEEG) meet all of the Daubert standards of scientific knowledge. Furthermore, the science and technical aspects of QEEG in measuring the effects of neurological and psychiatric dysfunction also match the recent Supreme Court standards of “technical” and “other specialized” knowledge (General Electric Co v. Joiner, 1997; Kumho Tire Company, Ltd. v. Carmichael, 1999) . Finally, it is shown that QEEG scientific knowledge and QEEG “technical” and “other specialized” knowledge meet the trilogy standards of the Supreme Court rulings in support of QEEG’s admissibility as a clinically valid method in the evaluation of the nature and extent of neurological and psychiatric disorders.
Journal of the Neurological Sciences
Volume 211, Issues 1-2 , 15 July 2003, Pages 1-3
Editorial: MRI cytoarchitectonics: the next level?
One expects that with technological advances in image acquisition and processing, continued refinement of functional MRI methodology, and other new modalities such as pathway imaging with diffusion tensor imaging, we will soon be able to produce beautiful and detailed in vivo images of the structure, function, and connectivity of the human brain.
Volume 184, Supplement 1 , November 2003, Pages 80-88
Insights into the pathophysiology of neuropathic pain through functional brain imaging
Kenneth L. Casey, , a, Jürgen Lorenzb and Satoshi Minoshimac
We present here an example case of neuropathic pain with heat allodynia as a major symptom to illustrate how the functional imaging of pain may provide new insights into the pathophysiology of painful sensory disorders. Tissue injury of almost any kind, but especially peripheral or central neural tissue injury, can lead to long-lasting spinal and supraspinal re-organization that includes the forebrain. These forebrain changes may be adaptive and facilitate functional recovery, or they may be maladaptive, preventing or prolonging the painful condition, and interfering with treatment. In an experimental model of heat allodynia, we used functional brain imaging to show that: (1) the forebrain activity during heat allodynia is different from that during normal heat pain, and (2) during heat allodynia, specific cortical areas, specifically the dorsolateral prefrontal cortex, can attenuate specific components of the pain experience, such as affect, by reducing the functional connectivity of subcortical pathways. The forebrain of patients with chronic neuropathic pain may undergo pathologically induced changes that can impair the clinical response to all forms of treatment. Functional imaging, including PET, fMRI, and neurophysiological techniques, should help identify brain mechanisms that are critical targets for more effective and more specific treatments for chronic, neuropathic pain.
Volume 20, Supplement 1 , November 2003, Pages S107-S111
Convergence and Divergence of Lesion Studies and Functional Imaging of Cognition
Illusory movements of the paralyzed limb restore motor cortex activity
In humans, limb amputation or brachial plexus avulsion (BPA) often results in phantom pain sensation. Actively observing movements made by a substitute of the injured limb can reduce phantom pain [Ramachandran and Rogers-Ramachandran, 1996], Proc. R. Soc. London B Biol. Sci. 263, 377–386). The neural basis of phantom limb sensation and its amelioration remains unclear. Here, we studied the effects of visuomotor training on motor cortex (M1) activity in three patients with BPA. Functional magnetic resonance imaging scans were obtained before and after an 8-week training program during which patients learned to match voluntary "movements" of the phantom limb with prerecorded movements of a virtual hand. Before training, phantom limb movements activated the contralateral premotor cortex. After training, two subjects showed increased activity in the contralateral primary motor area. This change was paralleled by a significant reduction in phantom pain. The third subject showed no increase in motor cortex activity and no improvement in phantom pain. We suggest that successful visuomotor training restores a coherent body image in the M1 region and, as a result, directly affects the experience of phantom pain sensation. Artificial visual feedback on the movements of the phantom limb may thus "fool" the brain and reestablish the original hand/arm cortical representation.
Volume 31, Issue 5 , September-October 2003, Pages 429-441
Individual differences in general intelligence correlate with brain function during nonreasoning tasks
Richard J. Haier, , Nathan S. White and Michael T. Alkire
Brain imaging can help identify the functional neuroanatomy of general intelligence (i.e., "g") and indicate how brain areas salient to g relate to information processing. An important question is whether individual differences in g among subjects are related to brain function even when nonreasoning tasks are studied. If so, this would imply that individuals with high g scores may process information differently even when no reasoning or problem solving is required. To further investigate this, we administered the Raven's Advanced Progressive Matrices (RAPM) test, a strong correlate of g, to 22 normal subjects and then measured cerebral glucose metabolic activity with PET while the subjects viewed videos on two occasions, tasks with no inherent reasoning or problem solving. Individual RAPM scores were correlated with regional brain activity using statistical parametric mapping (SPM99) conjunction analysis to combine both video conditions. Results showed greater activation in specific posterior brain areas (left BA37/19) in high RAPM scorers (P=.02, corrected for multiple comparisons). Subsequent analyses revealed a high/low RAPM group difference in functional connectivity between left BA37/19 activity and the left anterior cingulate/medial frontal gyrus. These data provide evidence that individual differences in intelligence correlate to brain function even when the brain is engaged in nonreasoning tasks and suggest that high and low g subjects may preferentially activate different neural circuits, especially nonfrontal areas involved in information processing.
Cingulate cortex hypoperfusion predicts Alzheimer's disease in mild cognitive impairment
Chaorui Huang , Lars-Olof Wahlund , Leif Svensson , Bengt Winblad and Per Julin
BMC Neurology 2002 2:9 (published 12 September 2002)
Mild cognitive impairment (MCI) was recently described as a heterogeneous group with a variety of clinical outcomes and high risk to develop Alzheimer's disease (AD). Regional cerebral blood flow (rCBF) as measured by single photon emission computed tomography (SPECT) was used to study the heterogeneity of MCI and to look for predictors of future development of AD. Methods: rCBF was investigated in 54 MCI subjects using Tc-99m hexamethylpropyleneamine oxime (HMPAO). An automated analysis software (BRASS) was applied to analyze the relative blood flow (cerebellar ratios) of 24 cortical regions. After the baseline examination, the subjects were followed clinically for an average of two years. 17 subjects progressed to Alzheimer's disease (PMCI) and 37 subjects remained stable (SMCI). The baseline SPECT ratio values were compared between PMCI and SMCI. Receiver operating characteristic (ROC) analysis was applied for the discrimination of the two subgroups at baseline. Results: The conversion rate of MCI to AD was 13.7% per year. PMCI had a significantly decreased rCBF in the left posterior cingulate cortex, as compared to SMCI. Left posterior cingulate rCBF ratios were entered into a logistic regression model for ROC curve calculation. The area under the ROC curve was 74%–76%, which indicates an acceptable discrimination between PMCI and SMCI at baseline. Conclusion: A reduced relative blood flow of the posterior cingulate gyrus could be found at least two years before the patients met the clinical diagnostic criteria of AD.
Mapping perception to action in piano practice: a longitudinal DC-EEG study
Marc Bangert and Eckart O Altenmüller
BMC Neuroscience 2003 4:26 (published 15 October 2003)
Performing music requires fast auditory and motor processing. Regarding professional musicians, recent brain imaging studies have demonstrated that auditory stimulation produces a co-activation of motor areas, whereas silent tapping of musical phrases evokes a co-activation in auditory regions. Whether this is obtained via a specific cerebral relay station is unclear. Furthermore, the time course of plasticity has not yet been addressed. Results: Changes in cortical activation patterns (DC-EEG potentials) induced by short (20 minute) and long term (5 week) piano learning were investigated during auditory and motoric tasks. Two beginner groups were trained. The 'map' group was allowed to learn the standard piano key-to-pitch map. For the 'no-map' group, random assignment of keys to tones prevented such a map. Auditory-sensorimotor EEG co-activity occurred within only 20 minutes. The effect was enhanced after 5-week training, contributing elements of both perception and action to the mental representation of the instrument. The 'map' group demonstrated significant additional activity of right anterior regions. Conclusion: We conclude that musical training triggers instant plasticity in the cortex, and that right-hemispheric anterior areas provide an audio-motor interface for the mental representation of the keyboard
Neuroimage. 2003 Nov;20 Suppl 1:S146-54.
Functional imaging and neuropsychology findings: how can they be linked?
It is argued that in poorly understood domains functional imaging and neuropsychology findings on cognitive processes can be related only through functional models of normal cognition. The psychological concept of "resource" can, however, be simply extrapolated to functional imaging. It is then argued that double dissociations can have analogous inferential power for extrapolation to models of normal cognition in functional imaging as in neuropsychology. The argument is illustrated by the example of the control processes involved in functional episodic memory imaging of experiments.
In Press, Corrected Proof , Available online 14 November 2003
One brain, two selves
A. A. T. S. Reinders, , a, E. R. S. Nijenhuisb, A. M. J. Paansc, J. Korfa, A. T. M. Willemsenc and J. A. den Boera
Having a sense of self is an explicit and high-level functional specialization of the human brain. The anatomical localization of self-awareness and the brain mechanisms involved in consciousness were investigated by functional neuroimaging different emotional mental states of core consciousness in patients with Multiple Personality Disorder (i.e., Dissociative Identity Disorder (DID)). We demonstrate specific changes in localized brain activity consistent with their ability to generate at least two distinct mental states of self-awareness, each with its own access to autobiographical trauma-related memory. Our findings reveal the existence of different regional cerebral blood flow patterns for different senses of self. We present evidence for the medial prefrontal cortex (MPFC) and the posterior associative cortices to have an integral role in conscious experience.
fMRI Evidence for Cortical Modification during Learning of Mandarin Lexical Tone.
Wang, Yue; Sereno, Joan; Jongman, Allard: Hirsch, Joy
Journal of Cognitive Neuroscience; 10/1/2003, Vol. 15 Issue 7, p1019-28
Functional magnetic resonance imaging was employed before and after six native English speakers completed lexical tone training as part Of a program to learn Mandarin as a second language. Language-related areas including Broca's area, Wernicke's area, auditory cortex, and supplementary motor regions were active in all subjects before and after training and did not vary in average location. Across all subjects, improvements in performance were associated with an increase in the spatial extent of activation in left superior temporal gyrus (Brodmann's area 22, putative Wernicke's area), the emergence of activity in adjacent Brodmann's area 42, and the emergence of activity in right inferior frontal gyrus (Brodmann's area 44), a homologue of putative Broca's area. These findings demonstrate a form of enrichment plasticity in which the early cortical effects of learning a tone-based second language involve both expansion of preexisting language-related areas and recruitment of additional cortical regions specialized for functions similar to the new language functions.
Journal of Clinical and Experimental
2003, Vol.25, No.8, pp. 1117-1127
A Controlled Quantitative MRI Volumetric Investigation of Hippocampal Contributions to Immediate and Delayed Memory Performance
H. Randall Griffith,
MRI volumetric TLE studies show inconsistent evidence of hippocampal involvement in memory. Prior studies have not dissociated hippocampal and temporal lobe contributions to memory. We measured hippocampal and temporal lobe volumes and immediate/delayed memory performances in 64 TLE patients. Regression was used to dissociate hippocampal from temporal lobe contributions to memory. Results revealed reliable evidence for dominant hippocampal involvement in delayed verbal recall across three separate measures and less consistent evidence for nondominant hippocampal involvement. The findings point to a consistent relationship of dominant hippocampal volumes to delayed verbal recall but no involvement of the temporal lobe or nondominant hippocampus in memory.
Neural Systems Underlying the Suppression of Unwanted Memories
Michael C. Anderson, Kevin N. Ochsner, Brice Kuhl, Jeffrey
Science, Volume 303, Number 5655, Issue of 9 Jan 2004, pp. 232-235.
Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.
The Where and When of Intention
Hakwan C. Lau,
Science 2004 303: 1208-1210
Intention is central to the concept of voluntary action. Using functional magnetic resonance imaging, we compared conditions in which participants made self-paced actions and attended either to their intention to move or to the actual movement. When they attended to their intention rather than their movement, there was an enhancement of activity in the pre-supplementary motor area (pre-SMA). We also found activations in the right dorsal prefrontal cortexand left intraparietal cortex. Prefrontal activity, but not parietal activity, was more strongly coupled with activity in the pre-SMA. We conclude that activity in the pre-SMA reflects the representation of intention.