9 research outputs found
Processing of spatial-frequency altered faces in schizophrenia: Effects of illness phase and duration
Low spatial frequency (SF) processing has been shown to be impaired in people with schizophrenia, but it is not clear how this varies with clinical state or illness chronicity. We compared schizophrenia patients (SCZ, n534), first episode psychosis patients (FEP, n522), and healthy controls (CON, n535) on a gender/facial discrimination task. Images were either unaltered (broadband spatial frequency, BSF), or had high or low SF information removed (LSF and HSF conditions, respectively). The task was performed at hospital admission and discharge for patients, and at corresponding time points for controls. Groups were matched on visual acuity. At admission, compared to their BSF performance, each group was significantly worse with low SF stimuli, and most impaired with high SF stimuli. The level of impairment at each SF did not depend on group. At discharge, the SCZ group performed more poorly in the LSF condition than the other groups, and showed the greatest degree of performance decline collapsed over HSF and LSF conditions, although the latter finding was not significant when controlling for visual acuity. Performance did not change significantly over time for any group. HSF processing was strongly related to visual acuity at both time points for all groups. We conclude the following: 1) SF processing abilities in schizophrenia are relatively stable across clinical state; 2) face processing abnormalities in SCZ are not secondary to problems processing specific SFs, but are due to other known difficulties constructing visual representations from degraded information; and 3) the relationship between HSF processing and visual acuity, along with known SCZ- and medication-related acuity reductions, and the elimination of a SCZ-related impairment after controlling for visual acuity in this study, all raise the possibility that some prior findings of impaired perception in SCZ may be secondary to acuity reductions
Are there differences in performance, metabolism, and quadriceps muscle activity in black African and Caucasian athletes during brief intermittent and intense exercise?
The purpose of the present study was to determine
whether there are any differences in power output (PO) and/or
quadriceps muscle (Quad) activity between black African and
Caucasian football players during a force-velocity (fv) exercise
test, which consisted of performing maximal 6-s sprints against
an increasing load. Each subject started the test with a load of 2
kg and then recovered for 5 min before repeating the same test
with a load increased by 2 kg. When the pedal frequency did not
exceed 130 rev·min–1, the load was increased by only 1 kg.
Each subject attained the load corresponding to his maximal
power if an additional increase in load (+1 kg) induced a power
decrease. Nine black Africans (mean age 24.2 ± 3.3 years) and
nine Caucasians (24.7 ± 4.2 years) (matched for stature and
aerobic fitness) participated in the fv exercise test. During the
test, PO, blood lactate, and the quadriceps electromyography
(EMG) root mean square (Quad RMS) were assessed. Higher
blood lactate was observed in Caucasians than in black Africans
for POs over the load range from 4 kg up to the maximal power.
However, PO and Quad RMS values were similar in Caucasians
and black Africans. They also had similar lean leg volume (LLV)
and consequently produced similar PO/LLV and Quad RMS/LLV
values. Overall, our results suggest that Caucasians and black
Africans matched for stature, max, and training background
have similar PO and Quad RMS values, but different blood lactate
concentrations during brief, intermittent, intense exercise
performed on a cycloergometer