EEG evidence of gender differences in a motor related CNV study.

In the present study gender differences related to the contingent negative variation (CNV) were investigated. A series of two acoustic stimuli was presented to participants across a wide age range. The first stimulus was consistent throughout the experiment whereas the second one was either a high frequency or a low frequency tone. One of them had to be answered by a button press (go condition) the other did not require any response (nogo condition). Between the first and the second tone there was a time period of two seconds in which the CNV appeared as a slow negative potential shift. Within this episode data were analysed with respect to gender differences. Statistical analysis revealed topographical differences between men and women in go conditions for both left and right index finger movements. Differences were found over frontal regions where women showed higher brain activity than men and over temporo-parietal regions where men produced higher brain activity than women. In order to explain the fact that only in "go" conditions significant gender differences occurred we introduce the phenomenon of implicit learning. Due to implicit learning assumed predictions related to S2 might have occurred from time to time. This is so, because a 50% chance for one of two different stimuli to occur leads to reasonable assumed predictions after two or more stimuli of a kind occurring in a series. The present data now provide evidence that if such assumed prediction or expectancy is directed towards an upcoming demand to act then brain activity is subject to gender differences. Further studies providing controlled sequences of "go" conditions versus "nogo" conditions have to be done to prove this idea true.

Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office.

The goal of this study was to investigate the impact of the essential oils of orange and lavender on anxiety, mood, alertness and calmness in dental patients. Two hundred patients between the ages of 18 and 77 years (half women, half men) were assigned to one of four independent groups. While waiting for dental procedures patients were either stimulated with ambient odor of orange or ambient odor of lavender. These conditions were compared to a music condition and a control condition (no odor, no music). Anxiety, mood, alertness and calmness were assessed while patients waited for dental treatment. Statistical analyses revealed that compared to control condition both ambient odors of orange and lavender reduced anxiety and improved mood in patients waiting for dental treatment. These findings support the previous opinion that odors are capable of altering emotional states and may indicate that the use of odors is helpful in reducing anxiety in dental patients.

Preserved memory traces within diencephalic amnesia.

A male patient with bilateral thalamic lesions (medio-ventral nuclei) was investigated. Despite explicit memory impairments his lexical ability was normal. We recorded magnetic field changes (magnetoencephalography, MEG) during the performance of an animate/inanimate discrimination task in which some words where repeated after long delays. Normally, repeated items are classified significantly faster than their first presentations which is accomplished by an unconscious process called priming. The patient did not show any behavioural evidence of priming but the physiological data indicated preservation of this robust form of memory. Brain activation associated with repetitions was attenuated at early stages. The activity difference was posteriorly distributed which is consistent with previous reports about repetition priming. The present study indicated that the bilateral thalamic lesions of our patient disconnected the information processing stream between the primed information and the behavioural response.

Event-related changes in neuromagnetic activity associated with syncopation and synchronization timing tasks.

For low rhythmic rates (1.0 to approximately 2.0 Hz), subjects are able to successfully coordinate finger flexion with an external metronome in either a syncopated (between the beats) or synchronized (on each beat) fashion. Beyond this rate, however, syncopation becomes unstable and subjects spontaneously switch to synchronization to maintain a 1:1 stimulus/response relationship. We used a whole-head magnetometer to investigate the spatiotemporal dynamics of neuromagnetic activity (MEG) associated with both coordinative patterns at eight different rates spanning the range 1.0-2.75 Hz. Timing changes in the event-related fields accompanied transitions from syncopation to synchronization and followed the placement of the motor response within each stimulus/response cycle. Decomposition of event-related fields into component auditory and motor brain responses revealed that the amplitude of the former decreased with increasing coordination rate whereas the motor contribution remained approximately constant across all rates. Such an interaction may contribute to changes in auditory-motor integration that cause syncopation to become unstable. Examination of event-related changes in high frequency bands revealed that MEG signal power in the beta band (15-30 Hz) was significantly lower during syncopated coordination in sensors covering the contralateral sensorimotor area suggesting a dependence of beta rhythm amplitude on task difficulty. Suppression of beta rhythms was also stronger during synchronization preceded by syncopation, e.g., after subjects had switched, when compared with a control condition in which subjects synchronized throughout the entire range of rates.

Neuromagnetic activity in alpha and beta bands reflect learning-induced increases in coordinative stability.

OBJECTIVE: To investigate how learning induced increases in stability on a syncopation task are manifest in the dynamics of cortical activity. METHOD: Magnetoencephalography was recorded from 143 sensors (CTF Systems, Inc). A pre-training procedure determined the critical frequency (F(c)) for each subject (n=4). Subjects either syncopated or synchronized to a metronome that increased in frequency from 1.2 to 3.0 Hz in 0.2 Hz steps. The F(c) was the point at which subjects spontaneously switched from syncopation to synchronization. Subjects then underwent 100 training trials (with feedback) at F(c). Following the learning phase the pre-training procedure was repeated. RESULTS: An increase in the F(c) occurred indicating that practice improved the stability of syncopation. The transition delay was also observed in the phase of the time-averaged signal in sensors over the contralateral sensorimotor area and in power analysis in the 8-12 Hz and 18-24 Hz frequency bands. Initially, reduced power was observed bilaterally during syncopation compared to synchronization. Following training, these differences were reduced or eliminated. CONCLUSION: Pre-training power differences can be explained by the greater difficulty of the syncopation task. The reduction in power differences following training suggests that at the cortical level, syncopation became more similar to synchronization possibly reflecting a decrease in task and/or attention demands.

Bilateral subthalamic nucleus stimulation does not improve prolonged P300 latencies in Parkinson's disease.

Bilateral deep brain stimulation is an effective treatment for most motor signs of Parkinson's disease (PD), but the effects on cognitive functions are less clear. We therefore examined the effects of bilateral deep brain stimulation on central information processing, using the event-related auditory P300 potential as an electrophysiological index of mental chronometry. Eight PD patients with bilateral stimulators within the subthalamic nuclei (STN) and eight age-matched controls participated. Patients were examined after overnight withdrawal of antiparkinson medication, both "on" and "off" stimulation (in random sequence). The P300 and reaction times were recorded using an auditory oddball paradigm. P300 latencies were prolonged in PD patients off stimulation (440 +/- 45 ms) compared to controls (397 +/- 16 ms; P < 0.05). STN stimulation significantly reduced clinical disease severity (as indexed by the Unified Parkinson's Disease Rating Scale) and markedly improved reaction times, but did not improve the prolonged P300 latencies in PD patients (429 +/- 36 ms). These results confirm that P300 latencies are prolonged in PD. Significantly, bilateral STN stimulation did not improve this electrophysiological measure of cognitive impairment, even though motor disability was markedly reduced. This suggests that some dopa-responsive features are resistant to STN stimulation, possibly due to involvement of dopaminergic deficits outside the nigrostriatal pathway, which are not influenced by outflow from the STN.

Modulation of spatial orientation processing by mental imagery instructions: a MEG study of representational momentum.

Under appropriate conditions, an observer's memory for the final position of an abruptly halted moving object is distorted in the direction of the represented motion. This phenomenon is called "representational momentum" (RM). We examined the effect of mental imagery instructions on the modulation of spatial orientation processing by testing for RM under conditions of picture versus body rotation perception and imagination. Behavioral data were gathered via classical reaction time and error measurements, whereas brain activity was recorded with the help of magnetoencephalography (MEG). Due to the so-called inverse problem and to signal complexity, results were described at the signal level rather than with the source location modeling. Brain magnetic field strength and spatial distribution, as well as latency of P200m evoked fields were used as neurocognitive markers. A task was devised where a subject examined a rotating sea horizon as seen from a virtual boat in order to extrapolate either the picture motion or the body motion relative to the picture while the latter disappeared temporarily until a test-view was displayed as a final orientation candidate. Results suggest that perceptual interpretation and extrapolation of visual motion in the roll plane capitalize on the fronto-parietal cortical networks involving working memory processes. Extrapolation of the rotational dynamics of sea horizon revealed a RM effect simulating the role of gravity in rotational equilibrium. Modulation of the P200m component reflected spatial orientation processing and a non-voluntary detection of an incongruity between displayed and expected final orientations given the implied motion. Neuromagnetic properties of anticipatory (Contingent Magnetic Variation) and evoked (P200m) brain magnetic fields suggest, respectively, differential allocation of attentional resources by mental imagery instructions (picture vs. body tilt), and a communality of neural structures (in the right centro-parietal region) for the control of both RM and mental rotation processes. Finally, the RM of the body motion is less prone to forward shifts than that of picture motion evidencing an internalization of the implied mass of the virtual body of the observer.

Reduced activation of midline frontal areas in human elderly subjects: a contingent negative variation study.

Contingent negative variation (CNV) was recorded from electrodes F7, F3, Fz, F4, F8, T7, C3, Cz, C4, T8, P7, P3, Pz, P4 and P8 in 19 young (mean age: 23 years) and 15 elderly (mean age: 66 years) healthy right-handed subjects, using a S2-choice paradigm. Young subjects showed early peak negativity shortly after the warning stimulus over mid-frontal areas, whereas for the remaining electrodes the negativity increased continuously. The amplitude of the early CNV was selectively reduced in elderly subjects over midline but not lateral frontal areas. We conclude that the activation of frontal midline areas as pre-supplementary motor area or anterior cingulate might be impaired in higher age.

[Hyperhomocyst(e)inemia--an independent risk factor of stroke]. / Hyperhomocyst(e)inämie--ein unabhängiger Risikofaktor des Schlaganfalls.

The total of free and protein-bound homocysteine including its derivatives is usually summarised as "homocyst(e)ine [H(e)]". Several congenital enzyme deficiencies may cause markedly elevated H(e) plasma levels, leading to the well-known clinical syndromes of homocystinuria. Recently, mild hyperhomocyst(e)inemia has been recognised as an independent risk factor for ischaemic cerebrovascular disease, coronary heart disease, and peripheral artery disease. H(e) levels are also related to the extent of atherosclerotic vessel wall alterations. The role of mild hyperhomocyst(e)inemia in venous thromboembolic disease, however, is not yet clear. A considerable proportion of patients with mild hyperhomocyst(e)inemia suffers from a deficiency of folate, vitamin B12, and/or vitamin B6. Supplementation of these agents--alone or combined with betain--leads to a decrease or even to a normalisation of elevated H(e) levels in the majority of such patients. Hitherto, no prospective randomised studies dealing with the clinical efficacy of such a--probably innocuous--supplementation have been performed. In the meantime, adequate alimentary intake of folate should be ensured.

Planning, preparation, execution, and imagery of volitional action.

There are different motor sets, which a human subject can be in or act from: he or she can be in a self-initiated voluntary movement set (action) or in a response set (re-action). Also, imagery sets are available that are necessary for the acquisition and practice of skill. Most important are such imagery sets for rehearsal in theatre, dance, music, sports, combat, etc.

beta-CIT SPECT demonstrates blockade of 5HT-uptake sites by citalopram in the human brain in vivo.

The cocaine analogue 2-beta-carbomethoxy-3-beta-(4-iodophenyl)-tropane (beta-CIT) is a potent ligand for both dopamine- and serotonin uptake sites which in its 123I labeled form can be used for single photon emission computerized tomography (SPECT). It was demonstrated previously by SPECT-studies in non-human primates that 123I-beta-CIT binds to dopamine transporters in the striatum and to serotonin transporters in hypothalamus and midbrain. The aim of the present study was to compare 123I-beta-CIT binding in the brain stem of normal controls and a group of subjects under treatment with the selective serotonin reuptake inhibitor (SSRI) citalopram. 123I-beta-CIT-SPECT was performed in 12 depressed patients under 20 mg (n = 5), 40 mg (n = 6) and 60 mg (n = 1) citalopram daily, in one untreated depressed patient and in 11 controls at regular time intervals up till 24 hours p.inj. A highly significant reduction of beta-CIT binding was found in an area including mesial thalamus, hypothalamus, midbrain and pons in patients under citalopram compared to controls (44.1 +/- 14.4 vs. 82.3 +/- 18.6cpm's/mCi x kg body weight; specific binding 4 hrs p.inj.; p = 0.0001). No differences were seen between the high and low dose group and no changes were found in the striatum. 123I-beta-CIT binding in the brain stem and striatum in one untreated depressed patient fell within the range of control values. To our knowledge this is the first report directly demonstrating the effect of a selective serotonin uptake inhibitor in the brain in humans in vivo. SPECT measurements of serotonin uptake sites in patients with depression and other psychiatric disorders might provide better insights into the pathophysiology of these disorders and into mechanisms of drug action.

Tactile mental imagery in sighted persons and in patients suffering from peripheral blindness early in life.

Patterns of cortical activity as measured by scalp-recorded event-related slow negative DC potential shifts were recorded in 9 early blind and 23 sighted normals while they imagined the feel of textures with the fingertips of one hand. All sighted subjects reported to have concomitant visual imagery as well. Hence, it was not surprising to observe occipital negative shifts, previously described as a sign of occipital visual cortex involvement in visual mental imagery. Though having never had visual perception, the blind, too, had occipital negativities. Their absolute amplitudes were smaller than in the sighted, not only occipitally but also and more pronounced at other areas, particularly frontally where amplitudes were even positive. On the hypothesis that the smaller overall amplitudes in the blind could obscure topographical differences between groups, the relative distribution of negativity across the scalp was assessed, using normalized data. Such normalized parameters significantly differed between groups, indicating that the occipital potentials of the blind were relatively more negative as related to the other scalp areas, than were the occipital potentials of the sighted as related to the other scalp areas. This occipital finding might indicate a participation of the blind's visually deprived occipital cortex in tactile imagery. Second, parietal DC potentials were maximal over the hemisphere contralateral to the imaging hand, possibly indicating involvement of the contralateral parietal association cortex in tactile imagery. Reasons why this was true only for the sighted, are discussed.

Cortical DC potential shifts accompanying auditory and visual short-term memory.

Negative DC potential shifts appeared over the scalp during the performance of verbal and non-verbal short-term memory tasks. Three items were successively presented (presentation of memory items) and then had to be retained in memory for 3 sec (memory retention) before being compared to a probe which was either a member (in set) or not a member (out of set) of the memory set. Verbal items (the digits "1" through "9") were tested in the auditory and visual modality and non-verbal items (musical notes) were tested in the auditory modality. Stimulus modality had a significant effect on DC potential shifts during both presentation of memory items and memory retention. There was a sustained negative shift during these periods which was larger over frontal regions with auditory than with visual material whereas the negative shift was larger over posterior temporal regions with visual than with auditory material. Out of 21 subjects who participated in the study, 9 reported the use of visual images in the auditory task, 5 used subvocal auditory rehearsal in the visual task and 7 used imagery concordant with the stimulus modality being memorized. These different strategies had a significant effect on the amplitudes and distribution of the DC potential shifts. The speed of response affected the amplitude of the DC potential shifts in the frontal regions, being larger with fast RTs than with slow RTs but only when verbal items were being processed. These results indicate that stimulus modality, modality of mental imagery, and speed of scanning of the memory store affect DC potential shifts during a 3 sec period of memory retention.

Thalamic ischemia in transient global amnesia: a SPECT study.

We performed 99mTc-HMPAO SPECT in a patient during transient global amnesia and twice thereafter. SPECT during the attack showed a significant diminution of regional blood flow in the left thalamus and a less marked diminution in the right thalamus. Quantitative evaluation of global 99mTc-HMPAO uptake indicated a diffuse depression of cerebral blood flow. At follow-up to 40 days after the attack, global uptake and thalamic flow indices normalized, but there was a persistent reduction of left frontal flow values.

Dopamine D2 receptor imaging with SPECT: studies in different neuropsychiatric disorders.

The purpose of the present study is to visualize and quantify dopamine D2 receptors in the living human brain using an 123I-labeled ligand and the single photon emission computerized tomography (SPECT) technique. S-(-)-Iodobenzamide [S-(-)-IBZM] has been shown to be a highly selective ligand with high affinity for D2 receptors in experimental studies. Five millicuries (185 MBq) of 123I-labeled S-(-)-IBZM was administered intravenously to 12 control subjects, 22 parkinsonian patients under L-Dopa therapy, 12 parkinsonian patients without L-Dopa, 10 unmedicated patients with Huntington's disease, and 12 patients under different neuroleptics. Data collection with a rotating double-head scintillation camera started 1 h after injection and lasted for 50 min. In a semiquantitative approach, a ratio was calculated between mean counts per pixel in the striatum and a region in the lateral frontal cortex, which was 1.74 +/- 0.10 in the control group. A marked reduction of this ratio was found in patients with Huntington's disease (1.38 +/- 0.12; p = 0.0001), no significant changes in untreated parkinsonian patients (1.67 +/- 0.14), but a reduction in L-Dopa-treated cases (1.59 +/- 0.13; p = 0.0014). A curvilinear relationship was found between total daily dose of neuroleptics and the reduction of this ratio. Estimated receptor blockade under full neuroleptic treatment was 75-80%. S-(-)-IBZM binding was reduced with increasing age (p less than 0.01). Specific binding was reduced markedly when the racemic mixture of IBZM was used, and no specific binding was seen with the R-(+)-isomer, demonstrating the stereoselectivity of IBZM binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Contributions of occipital and temporal brain regions to visual and acoustic imagery--a spect study.

Regional cerebral blood flow (rCBF) was assessed by means of HMPAO-SPECT in two experimental groups. In a control condition both groups listened to abstract words, in the experimental condition they heard five names of objects. One group was advised to form visual images of the objects, the other group was advised to form acoustic images of the sounds made by these objects. Post-experimental questionnaires revealed that most of the subjects in the acoustic imagery condition had had visual images in addition to the acoustic ones. Both imagery conditions lead to approximately equal increases of rCBF in the left inferior occipital region and in the left thalamus. Flow increases in both hippocampal regions and the right inferior and superior temporal regions were larger in the acoustic than in the visual imagery condition. It is concluded that only the activation of left inferior occipital and left thalamic regions can be interpreted as being related to modality-specific visual aspects of imagery.

[Therapeutic possibilities in spasmodic torticollis]. / Therapiemöglichkeiten beim Torticollis spasticus.

Spasmodic torticollis is classified as a focal dystonia. It is characterized by involuntary contractions of the muscles of the neck, with consequent deviation of the head from the correct posture. Psychological factors are recognized as important trigger and aggravating mechanisms. The various possibilities of therapeutic management (medical and surgical treatment, psychological methods and psychotherapy) are reviewed. Therapy of spasmodic torticollis should be started with methods such as biofeedback, behaviour therapy, and anticholinergic drugs. If these procedures not successful, local application of botulinum toxin offers a new and highly effective technique. Surgical treatment such as neurotomy, rhizotomy, or stereotaxic operations should be restricted to otherwise intractable cases.

Elaborative strategies in word pair learning--DC-potential correlates of differential frontal and temporal lobe involvement.

Cortical DC potentials were recorded while subjects were learning word pairs. The use of an elaborative mnemonic strategy resulted in a left frontal sustained negative shift. Its amplitude was independent of whether imagery mnemonics or semantic mnemonics were used. By contrast, posterior temporal potentials differed according to strategy: with imagery mnemonics, subjects had more symmetrical potentials over posterior temporal areas whereas with a semantic strategy, there was a left hemispheric preponderance of the DC potential. An interpretation within Stuss and Benson's theory on the frontal lobes is given.

Cerebral correlates of imagining colours, faces and a map--II. Negative cortical DC potentials.

Cortical activation patterns as measured by negative shifts of the scalp-recorded cortical steady potential ("DC shifts") were assessed in 28 normal subjects during imagining colours, faces, and a spatial map. Imaging resulted in sustained negative DC shifts at temporal, parietal and particularly at occipital sites. The topographic distributions of such DC shifts was modulated as a function of whether spatial or visual imagery was performed. During imaging the spatial map, a parietal maximum was observed, as opposed to a distribution in favour of temporal and occipital sites during imagining faces and colours. Results suggest a neuroanatomical dissociation between visual and spatial imagery. Since a similar visual-spatial dichotomy exists in perception, the finding is interpreted as further evidence of a shared cerebral substrate for images and percepts. The results are discussed in conjunction with the joint blood flow study.

Regional cerebral blood flow patterns in visual imagery.

Regional cerebral blood flow patterns were investigated by means of single photon emission computerized tomography in subjects who solved cognitive tasks which either did or did not require the use of visual imagery. In a first experiment judging the correctness of visual imagery sentences like "a grapefruit is bigger than an orange" led to increases of regional activity in inferior temporal and in the left inferior-occipital region when compared to blood flow patterns elicited by judgements about low imagery sentences or by responding differentially to "yes" and "no". Motor imagery sentences did not cause such an increase. In a second experiment a condition in which visual images were used for counting the corners of letters was compared to a condition in which subjects internally rehearsed the alphabet. The only difference concerned the inferior frontal regions which showed higher activity in rehearsing the alphabet. However, activity in inferior temporal and inferior occipital regions showed a positive correlation to the self-rated vividness of the visual images in the corner counting condition. The results of both experiments yield converging evidence that visual imagery is selectively related to activity of inferior-temporal and occipital regions. They thus support the hypothesis that the cerebral correlate of visual imagery is different from that of non-imaginal thinking.