The monkey premotor cortex contains neurons that discharge during action execution and during observation of actions made by others. Transcranial magnetic stimulation experiments suggest that a similar observation͞ execution matching system also is present in humans. We recorded neuromagnetic oscillatory activity of the human precentral cortex from 10 healthy volunteers while (i) they had no task to perform, (ii) they were manipulating a small object, and (iii) they were observing another individual performing the same task. The left and right median nerves were stimulated alternately (interstimulus interval, 1.5 s) at intensities exceeding motor threshold, and the poststimulus rebound of the rolandic 15-to 25-Hz activity was quantified. In agreement with previous studies, the rebound was strongly suppressed bilaterally during object manipulation. Most interestingly, the rebound also was significantly diminished during action observation (31-46% of the suppression during object manipulation). Control experiments, in which subjects were instructed to observe stationary or moving stimuli, confirmed the specificity of the suppression effect. Because the recorded 15-to 25-Hz activity is known to originate mainly in the precentral motor cortex, we concluded that the human primary motor cortex is activated during observation as well as execution of motor tasks. These findings have implications for a better understanding of the machinery underlying action recognition in humans.

We recorded whole-scalp magnetoencephalographic (MEG) signals simultaneously with surface electromyographic (EMG) activity from eight patients with Parkinson's disease after withdrawal and reinstatement of treatment with levodopa. Variations were seen in the coherence between the forearm extensor EMG and the MEG signal originating near or in the hand region of the primary motor cortex. As a group, the parkinsonian patients withdrawn from levodopa showed a reduction in the coherence at 15-30 Hz and 35-60 Hz, and a further three untreated patients had abnormally strong MEG-EMG coherence at 5-12 Hz compared with when medicated or with eight healthy age-matched control subjects. We conclude that the basal ganglia have a specific effect on the temporal organization of motor cortical activity during voluntary tonic contraction. Abnormalities in this aspect of basal ganglia function may directly contribute to bradykinesia and weakness in Parkinson's disease.

Subjects with Asperger's syndrome (AS) are impaired in social interaction and imitation, but the underlying brain mechanisms are poorly understood. Because the mirror-neuron system (MNS) that matches observed and executed actions has been suggested to play an important role in imitation and in reading of other people's intentions, we assessed MNS functions in 8 adult AS subjects and in 10 healthy control subjects during imitation of still pictures of lip forms. In the control subjects, cortical activation progressed in 30 to 80-millisecond steps from the occipital cortex to the superior temporal sulcus, to the inferior parietal lobe, and to the inferior frontal lobe, and finally, 75 to 90 milliseconds later, to the primary motor cortex of both hemispheres. Similar activation sites were found in AS subjects but with slightly larger scatter. Activation of the inferior frontal lobe was delayed by 45 to 60 milliseconds and activations in the inferior frontal lobe and in the primary motor cortex were weaker than in control subjects. The observed abnormal premotor and motor processing could account for a part of imitation and social impairments in subjects with AS.

Objectives: To determine the long term survival and predictors of death in patients with primary intracerebral haemorrhage (ICH) in Central Finland. Methods: Data were collected retrospectively on all adult patients with first ever ICH in Central Finland county between September 1985 and December 1991. The survival of all patients at the end of December 2002 was investigated. Kaplan-Meier survival curves were constructed and factors associated with both early ((28 days) and late deaths determined. Long term survival was compared with the general Finnish population of the same age and sex distribution. The causes of death were compared with those of the population of Central Finland. Results: 411 patients with first ever ICH were identified, 199 men (mean age 64.9 years) and 212 women (mean age 69.5); 30 died before hospital admission, and 208 (50.6%) within the first 28 days. In KaplanMeier analysis, at 16 years the cumulative survival was 3.2% for men and 9.8% for women. The 28 day survivors had a 4.5-fold increased annual risk of dying during the first year after ICH, and 2.2-fold during years 2 to 6. On admission, significant independent predictors of death within the first four weeks were unconsciousness, lateral shift of cerebral midline structures, mean arterial pressure >134 mm Hg, hyperglycaemia, anticoagulant treatment, and ventricular extrasystoles. Predictors of late death for the 28 day survivors were old age, male sex, and heart failure. Conclusions: Primary intracerebral haemorrhage has a poor short and long term outcome. The results emphasise the importance of primary and secondary prevention for ICH.

We studied attentional modulation of cortical processing of faces and houses with functional MRI and magnetoencephalography (MEG). MEG detected an early, transient face-selective response. Directing attention to houses in ''double-exposure'' pictures of superimposed faces and houses strongly suppressed the characteristic, face-selective functional MRI response in the fusiform gyrus. By contrast, attention had no effect on the M170, the early, face-selective response detected with MEG. Late (>190 ms) category-related MEG responses elicited by faces and houses, however, were strongly modulated by attention. These results indicate that hemodynamic and electrophysiological measures of face-selective cortical processing complement each other. The hemodynamic signals reflect primarily late responses that can be modulated by feedback connections. By contrast, the early, face-specific M170 that was not modulated by attention likely reflects a rapid, feedforward phase of face-selective processing.functional MRI ͉ human ͉ magnetoencephalography ͉ visual V iewing faces evokes responses in ventral temporal cortex that have a distinctive spatial topography that can be observed with functional magnetic resonance imaging (1-8) and a distinctive temporal course that can be observed with magnetoencephalography (MEG) (1, 9-13) and electroencephalography (EEG) (10, 14-21). The spatial pattern of hemodynamic cortical response that is measured with fMRI has a maximum in the fusiform face area in the lateral fusiform gyrus, (3,4,7,8,22,23). The temporal electrophysiological response that is measured with MEG (or EEG) contains an early field (or potential) that peaks Ϸ170 ms after the appearance of a face, the M170 (or N170) response (1, 9-21). Both source modeling of MEG signals (9, 10, 12) and EEG recordings made directly from the cortical surface (14) suggest that the M170͞N170 response is generated by activity in ventral and lateral extrastriate regions, including the fusiform gyrus.MEG͞EEG and fMRI complement each other insofar as MEG and EEG signals generated by neural activity can resolve temporal events on a millisecond time scale but with limited spatial resolution, especially for multiple, distributed sources (24), whereas fMRI has relatively high spatial resolution but coarse temporal resolution because it measures slower hemodynamic changes elicited by neural activity (25). The fMRI hemodynamic measures reflect metabolic demand, whereas MEG͞EEG measures reflect electrophysiological activity and are influenced strongly by the synchrony of neuronal activity. Consequently, these measures may be dissociated when the activity is synchronous but brief, resulting in a small metabolic demand, or when it reflects a resetting of the phase of the spontaneous activity with no change in power. The faceselectivity and similar cortical locations of the fusiform face area and M170͞N170 responses suggest that they reflect the same neural activity. Here we show, however, that these responses can be dissociated by the effect of attention. Th...

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The most important predictor of the 28-day survival was the level of consciousness on admission, followed by first-day MAP. Hypertension was the most important predictor of the first-day MAP, followed by age, which had an inverse effect on the MAP level. At all levels of consciousness, high first-day MAP (especially if > 145 mm Hg) worsened the 28-day survival rate.