Thomas C Floyd

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Visual measurements of sleep spindles were carried out in 48 elderly and 20 young normal adults. Computed tomography brain scans and psychometric testing were also performed. Earlier findings of reduced spindle abundance, amplitude and duration in the elderly were confirmed. In addition, we demonstrated a linear increase in spindle density and duration(More)
The authors studied the scalp topography of P300 responses to novel auditory stimuli and its relationship to negative symptoms in medication-free hospitalized schizophrenic patients. Schizophrenics (n = 12), patients with major mood disorders (n = 13), and 17 non-ill controls (all men) responded to rare target tones while ignoring background tones and rare(More)
It has been hypothesized that visually scored stage 4 EEG (dense, high amplitude 0.5-3 Hz (delta) waves) is a correlate of a metabolic process that reverses some of the effects of waking on the brain. The results of nap studies appear inconsistent with this hypothesis since late naps produce a disproportionate loss of stage 4 during subsequent sleep. We(More)
One night's sleep loss in young adults increased delta (0.3-3 Hz) EEG only in the first non-REM period of recovery sleep. The delta increase was limited to frequencies 0.3-4 Hz; within this range, the effects on wave form periods and amplitudes differed by frequency band. These results illustrate the value of computer analysis applied to the physiological(More)
The relationship between frontal lobe phospholipid measures as measured by in vivo 31phosphorus magnetic resonance spectroscopic imaging and performance on the Wisconsin Card Sort Test was examined in 16 chronic schizophrenic patients and 13 normal controls. Lower left frontal phosphomonoester levels in the schizophrenics were associated with fewer(More)
Repeated administration of flurazepam reduced stage 4 sleep (high delta-wave concentration) but produced a greater increase in stage 2 duration so that total sleep time was increased. Computer analysis revealed that the increased amount of stage 2 (low delta-wave concentration) sleep provided a number and duration of delta waves sufficient to offset the(More)
Very low levels of visually scored stage 4 sleep are found in 40% to 50% of acute and chronic schizophrenics. Stage 4 is a visual estimate of high-amplitude delta (0.5 to 3 Hz) electroencephalographic waves; these waves can now be measured directly and reliably by computer. In this pilot study, we carried out such measurement in the successive(More)
The authors previously reported that negative symptoms were associated with reduced EEG alpha power and coherence in medication-free schizophrenic inpatients. These post-hoc findings were based on resting EEG data in an eyes open condition. This report describes the replication of these results in a new sample of 17 male veterans (aged 38 +/- 8) recently(More)