Psychopathic traits in Finnish homicide offenders with schizophrenia.

There is a paucity of studies examining psychopathy in comparable samples of violent individuals with and without psychotic illness. The main goal of the study was to assess the prevalence and nature of psychopathic traits as measured by PCL-R among Finnish homicide offenders with schizophrenia. Further, the impact of co-morbid psychopathy on the homicidal incidents, as well as the associations of psychopathy and offender background factors, among offenders with schizophrenia was investigated.

Homicides with mutilation of the victim's body.

Information on homicide offenders guilty of mutilation is sparse. The current study estimates the rate of mutilation of the victim's body in Finnish homicides and compares sociodemographic characteristics, crime history, life course development, psychopathy, and psychopathology of these and other homicide offenders. Crime reports and forensic examination reports of all offenders subjected to forensic examination and convicted for a homicide in 1995-2004 (n = 676) were retrospectively analyzed for offense and offender variables and scored with the Psychopathy Check List Revised.

Finnish sexual homicides: offence and offender characteristics.

Information on sexual homicide offenders is limited. The current study estimates the rate of sexual homicides in Finland and analyses sociodemographic characteristics, crime history, life course development, psychopathy, and psychopathology in sexual homicide and nonsexual homicide offenders. Crime reports and forensic examination reports of all offenders subjected to forensic examination and convicted for homicide in 1995-2004 (n=676) were retrospectively analyzed for offence and offender variables and scored with the Psychopathy Checklist-Revised.

Reproducibility of cortex-muscle coherence.

Cortex-muscle coherence is a frequency-analysis technique that has been increasingly applied in the investigation of movement disorders. To study the intra- and inter-session stability of the cortex-muscle coherence, we recorded from 12 healthy subjects magnetoencephalographic (MEG) and surface electromyographic (EMG) signals during unilateral isometric contractions of the left- and right-hand muscles. Two identical measurements were performed during one session, and the session was repeated once after about 1 year.

Short-term (approximately 600 ms) prediction of perturbation dynamics for 10- and 20-Hz MEG rhythms in human primary sensorimotor hand cortices.

The pericentral primary sensorimotor cortices generate the "mu rhythm" with a distinct spectral signature exhibiting two peaks, generated predominantly anterior (20 Hz) or posterior (10 Hz) to the central sulcus; it defines a "background" network state upon which somatosensory inputs will impinge. We used the high spatiotemporal resolution of magnetoencephalography to analyze the perturbation dynamics of these cortical rhythms in response to a series of paired electric median nerve stimuli: single trials were sorted off-line according to increasing power of the 10- or 20-Hz rebounds which occurred 300-600 ms after the first stimulus; using subaverages formed from the upper and lower 20% of this distribution, we analyzed somatosensory evoked fields (SEF) and power modifications caused by the second stimulus in the pair. We report three key findings: (1) the power level of rhythm rebounds triggered by the first stimulus predicted the rebound strength after the second stimulus applied 600 ms later; yet, it was uncorrelated across the 2.

Synchronous cortical oscillatory activity during motor action.

Oscillations of the motor cortex interact with similar activity of the spinal motoneuron pool in the 15-30 Hertz frequency range. Recent observations have demonstrated how this interaction affects the firing of single corticospinal neurons. The interaction, reflected as corticomuscular coherence, occurs for both distal and proximal muscles and it constitutes one connection in a larger web of oscillatory interactions, including several other motor areas in the cortex, thalamus, and cerebellum.

Modulation of cortex-muscle oscillatory interaction by ischaemia-induced deafferentation.

We studied the effect of sensory feedback on the oscillatory interaction between activity of the motor cortex and the spinal motoneuron pool during isometric contraction. After inducing ischaemic sensory deafferentation in the upper limb in six subjects, we calculated coherences between simultaneously recorded whole-scalp magnetoencephalographic (MEG) signals and electromyographic (EMG) signals from the first dorsal interosseus muscles. We expected that the dominant frequency of coherence would change if there were interaction through a sensory feedback loop.

Cortico-muscular coupling in a human subject with mirror movements--a magnetoencephalographic study.

We studied cortico-muscular coupling in a 15-year-old male suffering from congenital mirror movements (MMs) of hands. Cortex-muscle coherence was analyzed between magnetoencephalographic signals and the electromyograms (EMGs) recorded from both hands and feet during uni- and bilateral isometric contractions. Regardless of the side of the intended contraction, the motor cortex contralateral to the contraction was coupled to the muscles of both hands at 20-25 Hz.

Defective cortical drive to muscle in Parkinson's disease and its improvement with levodopa.

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.