| 1. |
- Akgül, Özge, et al.
(author)
-
Reduced Reward Processing in Schizophrenia : A Comprehensive EEG Event-Related Oscillation Study
- 2024
-
In: Brain Topography. - : Springer. - 0896-0267 .- 1573-6792. ; 37:1, s. 126-137
-
Journal article (peer-reviewed)abstract
- It is well known that abnormal reward processing is a characteristic feature of various psychopathologies including schizophrenia (SZ). Reduced reward anticipation has been suggested as a core symptom of SZ. The present study aims to evaluate the event-related oscillations (EROs) delta, theta, alpha, beta, and gamma in patients with SZ during the Monetary Incentive Delay (MID) task, which elicits the neural activity of reward processing. Twenty-one patients with SZ and twenty-two demographically matched healthy controls were included in the study. EROs were compared between groups and correlation analyses were conducted to determine a possible relationship between clinical scores and ERO values. Compared with healthy controls, the SZ group had reduced (1) delta and theta amplitudes in the reward condition (2) total beta and non-incentive cue-related beta amplitudes, and (3) incentive cue-related frontal gamma amplitudes. These reductions can be interpreted as impaired dopaminergic neurotransmission and disrupted cognitive functioning in the reward processing of SZ. In contrast, SZ patients showed higher incentive cue-related theta and occipital gamma amplitudes compared to controls. These increments may reflect negative symptoms in SZ. Moreover, theta amplitudes showed a negative correlation with Calgary Depression Scale for Schizophrenia scores and a positive correlation with attentional impulsivity. This is the first study showing the impairments of SZ patients in EROs from delta to gamma frequency bands compared with healthy controls during reward anticipation. Being the first comprehensive study, our results can be interpreted as providing evidence for disrupted brain dynamics in the reward processing of SZ studied by EROs. It may become possible to help patients' wellness by improving our understanding of reward processing in schizophrenia and developing innovative rehabilitation treatments based on these findings.
|
|
| 2. |
- Egorova, Natalia, et al.
(author)
-
Neural Dynamics of Speech Act Comprehension: An MEG Study of Naming and Requesting
- 2014
-
In: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 27:3, s. 375-392
-
Journal article (peer-reviewed)abstract
- The neurobiological basis and temporal dynamics of communicative language processing pose important yet unresolved questions. It has previously been suggested that comprehension of the communicative function of an utterance, i.e. the so-called speech act, is supported by an ensemble of neural networks, comprising lexico-semantic, action and mirror neuron as well as theory of mind circuits, all activated in concert. It has also been demonstrated that recognition of the speech act type occurs extremely rapidly. These findings however, were obtained in experiments with insufficient spatio-temporal resolution, thus possibly concealing important facets of the neural dynamics of the speech act comprehension process. Here, we used magnetoencephalography to investigate the comprehension of Naming and Request actions performed with utterances controlled for physical features, psycholinguistic properties and the probability of occurrence in variable contexts. The results show that different communicative actions are underpinned by a dynamic neural network, which differentiates between speech act types very early after the speech act onset. Within 50-90 ms, Requests engaged mirror-neuron action-comprehension systems in sensorimotor cortex, possibly for processing action knowledge and intentions. Still, within the first 200 ms of stimulus onset (100-150 ms), Naming activated brain areas involved in referential semantic retrieval. Subsequently (200-300 ms), theory of mind and mentalising circuits were activated in medial prefrontal and temporo-parietal areas, possibly indexing processing of intentions and assumptions of both communication partners. This cascade of stages of processing information about actions and intentions, referential semantics, and theory of mind may underlie dynamic and interactive speech act comprehension.
|
|
| 3. |
|
|
| 4. |
- Genna, Clara, et al.
(author)
-
Spatiotemporal Dynamics of the Cortical Responses Induced by a Prolonged Tactile Stimulation of the Human Fingertips
- 2017
-
In: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 30:4, s. 473-485
-
Journal article (peer-reviewed)abstract
- The sense of touch is fundamental for daily behavior. The aim of this work is to understand the neural network responsible for touch processing during a prolonged tactile stimulation, delivered by means of a mechatronic platform by passively sliding a ridged surface under the subject’s fingertip while recording the electroencephalogram (EEG). We then analyzed: (i) the temporal features of the Somatosensory Evoked Potentials and their topographical distribution bilaterally across the cortex; (ii) the associated temporal modulation of the EEG frequency bands. Long-latency SEP were identified with the following physiological sequence P100—N140—P240. P100 and N140 were bilateral potentials with higher amplitude in the contralateral hemisphere and with delayed latency in the ipsilateral side. Moreover, we found a late potential elicited around 200 ms after the stimulation was stopped, which likely encoded the end of tactile input. The analysis of cortical oscillations indicated an initial increase in the power of theta band (4–7 Hz) for 500 ms after the stimulus onset followed a decrease in the power of the alpha band (8–15 Hz) that lasted for the remainder of stimulation. This decrease was prominent in the somatosensory cortex and equally distributed in both contralateral and ipsilateral hemispheres. This study shows that prolonged stimulation of the human fingertip engages the cortex in widespread bilateral processing of tactile information, with different modulations of the theta and alpha bands across time.
|
|
| 5. |
|
|
| 6. |
- Larsson, Pål G., et al.
(author)
-
A New Method for Quantification and Assessment of Epileptiform Activity in EEG with Special Reference to Focal Nocturnal Epileptiform Activity
- 2009
-
In: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 22:1, s. 52-59
-
Journal article (peer-reviewed)abstract
- Quantification of epileptiform activity in EEG has been applied for decades. This has mainly been done by visual inspection of the recorded EEG. There have been many attempts using computers to quantify the activity, usually with moderate success. In a row of contexts, including Landau-Kleffner syndrome and the syndrome of epilepsy with continuous spike wave during slow sleep, the spike index (SI) has been applied to quantify [Symbol: see text]interictal nocturnal focal epileptiform activity', which is suggested as a general term for the epileptiform activity enhanced by sleep. However, the SI has been implemented differently by different authors and has usually not been well described and never properly defined. This study suggests a definition of SI that gives a semiautomatic and relatively robust algorithm for assessment. The method employs spike detection by means of template matching of the current source density estimate. The percentage of time within an epoch with interspike interval (ISI) below a given limit, usually 3 s, is returned as the SI. This is calculated during daytime and in non-REM sleep. The standard epoch length is 10 min. The parameter selection is discussed in the context of the influence of spikes and bursts on cognition. The described method gives reproducible results in routine use, gives clinical valuable information, and is easily implemented in a clinical setting. There is only a minor added workload for the electroencephalographer.
|
|
| 7. |
- Larsson, Pål G., et al.
(author)
-
Decrease in Propagation of Interictal Epileptiform Activity After Introduction of Levetiracetam Visualized with Electric Source Imaging
- 2010
-
In: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 23:3, s. 269-278
-
Journal article (peer-reviewed)abstract
- Different neuroimaging techniques (fMRI, spectroscopy, PET) are being used to evaluate candidate drugs in pharmacological development. In patients with epilepsy fast propagation of the epileptiform activity between different brain areas occurs. Electric Source Imaging (ESI), in contrast to the aforementioned techniques, has a millisecond time resolution, allowing visualization of this fast propagation. The purpose of the current project was to use ESI to investigate whether introduction of an antiepileptic drug (levetiracetam, LEV) would change the propagation patterns of the interictal epileptiform activity. Thirty patients with epilepsy were subject to an EEG recording before (pre-LEV) and after (in-LEV) introduction of LEV. Interictal spikes with similar topographic distribution were averaged within each subject, and a distributed source model was used to localize the EEG sources of the epileptiform activity. The temporal development of the activity within 20 regions of interest (ROIs) was determined, and source propagation between different regions was compared between the pre-LEV and in-LEV recordings. Patients with epileptic seizures showed propagation in 22/24 identified spike types in the pre-LEV recordings. In the in-LEV recordings only 7/15 spike types showed propagation, and six of these seven propagating spikes were recorded in patients with poor effect of treatment. Also in patients without seizures LEV tended to suppress propagation. We conclude that the observed suppression of source propagation can be considered as an indicator of effective antiepileptic treatment. ESI might thus become a useful tool in the early clinical evaluation of new candidate drugs in pharmacological development.
|
|
| 8. |
- Orekhova, Elena V, 1967, et al.
(author)
-
Auditory Magnetic Response to Clicks in Children and Adults: Its Components, Hemispheric Lateralization and Repetition Suppression Effect
- 2013
-
In: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 26:3, s. 410-427
-
Journal article (peer-reviewed)abstract
- The auditory magnetic event-related fields (ERF) qualitatively change through the child development, reflecting maturation of auditory cortical areas. Clicks presented with long inter-stimulus interval produce distinct ERF components, and may appear useful to characterize immature EFR morphology in children. The present study is aimed to investigate morphology of the auditory ERFs in school-age children, as well as lateralization and repetition suppression of ERF components evoked by the clicks. School-age children and adults passively listened to pairs of click presented to the right ear, left ear or binaurally, with 8-11 s intervals between the pairs and a 1 s interval within a pair. Adults demonstrated a typical P50m/N100m response. Unlike adults, children had two distinct components preceding the N100m-P50m (at similar to 65 ms) and P100m (at similar to 100 ms). The P100m dominated the child ERF, and was most prominent in response to binaural stimulation. The N100m in children was less developed than in adults and partly overlapped in time with the P100m, especially in response to monaural clicks. Strong repetition suppression was observed for P50m both in children and adults, P100m in children and N100m in adults. Both children and adults demonstrated ERF amplitude and/or latency right hemispheric advantage effects that may reflect right hemisphere dominance for preattentive arousal processes. Our results contribute to the knowledge concerning development of auditory processing and its lateralization in children and have implications for investigation of the auditory evoked fields in developmental disorders.
|
|
| 9. |
|
|
| 10. |
- Rodriguez, G, et al.
(author)
-
Regional cerebral blood flow asymmetries in a group of 189 normal subjects at rest
- 1991
-
In: Brain Topography. - 0896-0267 .- 1573-6792. ; 4:1, s. 57-63
-
Journal article (peer-reviewed)abstract
- Regional cerebral blood flow (rCBF) asymmetries were studied in 189 subjects (96 males and 93 females) at rest with the 133Xenon inhalation method using a fixed detector system. rCBF asymmetries in the resting condition were very small, nevertheless a significant (p less than 0.001) effect for their topographical distribution was present, reflecting higher rCBF in the right fronto-temporal and left parieto-occipital regions. rCBF asymmetries were not correlated with age, and there were no significant differences between males and females. Asymmetries are therefore useful from a statistical point of view in detecting rCBF abnormalities in the resting condition: they are more stable than absolute values in normal subjects and no matching according to age or sex is required when statistical comparisons are performed.
|
|
