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Biomedical subjects

Philip C Njemanze

Publications and source records attributed to Philip C Njemanze.

5 recordsLinked to original sources
PubMed2007

Cerebral lateralisation for facial processing: gender-related cognitive styles determined using Fourier analysis of mean cerebral blood flow velocity in the middle cerebral arteries.

Facial processing was studied in 16 (eight men and eight women) right-handed healthy participants using a new functional transcranial Doppler technique called functional transcranial Doppler spectroscopy (fTCDS). MFV was recorded simultaneously in both right and left middle cerebral arteries in dark condition and during visual processing of object and facial tasks. fTCDS used Fourier analysis of mean flow velocity (MFV) time series to derive spectral density estimates that correlate with expected mental activity. Men were right lateralised for object and facial perception, while women were left lateralised for facial tasks but showed a right tendency or no lateralisation for object perception. For facial perception, men used a category-specific process-mapping system for right cognitive style, but women used same for the left.

Adult↗
PubMed2005

Cerebral lateralization and general intelligence: gender differences in a transcranial Doppler study.

The present study evaluated cerebral lateralization during Raven's progressive matrices (RPM) paradigm in female and male subjects. Bilateral simultaneous transcranial Doppler (TCD) ultrasound was used to measure mean blood flow velocities (MBFV) in the right and left middle cerebral arteries (MCAs) in 24 (15 females and 9 males) right-handed normal subjects. The female subjects used a left hemisphere strategy, while males used a right hemisphere strategy to successfully solve RPM tasks. This implies that general intelligence is associated with neural systems within one hemisphere that are accessible to a variety of cognitive processes.

Adult↗
PubMed2004

Asymmetry in cerebral blood flow velocity with processing of facial images during head-down rest.

INTRODUCTION: Ability to interpret facial expression is crucial for non-verbal communication among humans, and could be affected by changes in cerebral circulation during exposure to microgravity or its simulation. METHODS: There were 16 subjects (8 men and 8 women) who were exposed to 24 h of -6 degrees head-down rest (HDR). Transcranial Doppler ultrasonography was used to monitor mean blood flow velocity (MBFV) in the middle cerebral arteries bilaterally during processing of facial images before, at 6 and 24 h of HDR, and after HDR (Pre-, 6H-, 24H-, and Post-HDR, respectively). The laterality index was assessed as side-to-side differences in MBFV relative to Pre-HDR for each condition. RESULTS: For Pre-HDR, both objects and faces were right lateralized in men (p < 0.001) and showed a left lateralization tendency in women (p > 0.05). At 6H-HDR, both object and faces were left lateralized in men (p < 0.05), but right lateralized in women (p < 0.001). At 24H-HDR, both men and women were left lateralized (p < 0.05). For Post-HDR, both remained left lateralized for all tasks (p < 0.05). DISCUSSION: HDR alters cerebral lateralization for object and facial stimuli, with opposing tendencies in men and women. The gender differences may reflect peculiarities in processing strategy for object and faces between men and women. Men use a right hemisphere processing strategy for faces and women a left hemisphere strategy. The superiority of processing of faces by women compared with men has been attributed to left hemisphere based strategy. HDR alters lateralization patterns and may thus alter processing strategies for faces.

Adult↗
PubMed2002

Cerebral lateralization for motor tasks in simulated microgravity a transcranial Doppler technique for astronauts.

In Space, central cognitive operations are unaffected but humans are slower in perceptual-motor performance. Transcranial Doppler ultrasonography was used to monitor blood flow velocity in both middle cerebral arteries during unilateral and bilateral fingers' movements before, during and after -6 degrees 24 hours of head-down tilt (HDT) in 14 (8 males and 6 females) subjects. Physiologic hemisphere dominance was assessed by breath-holding test. There was a significant main effect of motor task, F(4, 328) = 16.05, p<0.00000001, MSe = 48.2. There was a gender vs head-position interaction F(3,246) = 4.90 p<0.002) MSe = 120. At pre-HDT females were right lateralized and males were left lateralized. A left shift in lateralization pattern was seen during 24hrs-HDT for both genders. There was a significant main effect of breath-holding test and a breath-holding test vs head position vs motor task interaction. HDT alters cerebral lateralization for motor control and this may be responsible for slowing in perceptual-motor performance in Space. TCD monitoring may be required for motor performance tasks in Space.

Journal Article↗