Dennis J. Beckley

Abnormal premovement brain potentials in schizophrenia

Authors:

  • Jaswinder Singh

  • Robert T. Knight

  • Nicholas Rosenlicht

  • Joan M. Kotun

  • Dennis J. Beckley

  • David L. Woods

Date: 1992

PubMed: 1358184

View PDF

Abstract:

We assessed scalp-recorded movement related potentials (MRPs) generated prior to voluntary movements in chronic, medicated schizophrenics (n = 9) and age matched normal controls (n = 9). MRPs were recorded in a self-paced button press task in which subjects pressed a button with either their right, left or both thumbs (experimental condition I, II and III respectively). Controls generated a slowly rising readiness potential (RP) at about 1000 ms, a negative shift (NS') at about 450 ms and a motor potential (MP) at about 100 ms prior to movement. The initial MRP components (RP and NS') were reduced in schizophrenics indicating an impairment of the voluntary preparatory process in schizophrenia. Results of the present study indicate a similarity of MRP findings in schizophrenics and reported MRPs (Singh and Knight, 1990) in patients with unilateral lesions of the dorsolateral prefrontal cortex. These findings provide further support for frontal lobe dysfunction in schizophrenia.

Lack of age effects on human brain potentials preceding voluntary movements

Authors:

  • Jaswinder Singh

  • Robert T. Knight

  • David L. Woods

  • Dennis J. Beckley

  • Clay Clayworth

Date: 1990

PubMed: 2097580

View PDF

Abstract:

We examined age effects on Movement related potentials (MRPs) in 13 young (mean age = 29.3 years) and 13 old (mean age = 67.2 years) normal adults in right, left and bimanual self-paced button press conditions. Both the groups generated a slowly rising readiness potential (RP) at about 1000 ms, a negative shift (NS') at about 450 ms and a motor potential (MP) at about 100 ms prior to movement. The RP was symmetrical, bilaterally distributed and maximal at the vertex in all conditions in both the groups. Both the groups produced contralateraUy enhanced NS' and MP compo- nents in unimanual conditions. In contrast to prior reports, topographical distribution, onset latency and mean amplitude were comparable between young and old subjects for the RP, NS' and MP components of the MRP. The results indicate that motor programming as indexed by MRPs is unaffected by normal aging.

Movement related potentials in patients with MPTP-induced Parkinsonism and early and late Parkinsonism

Authors:

  • Jaswinder Singh

  • B. R. Bloem

  • Robert T. Knight

  • William Jagust

  • David L. Woods

  • Dennis J. Beckley

  • J. Tetrud

  • J. W. Langston

Date: 1990