Institute of Neurocybernetics
Chidicon Medical Center,
International Institutes of Advanced Research and Training, Owerri, Imo State, Nigeria
Our Mission
Our interest is to study control mechanisms of brain function as it    
relates to:
  • Hemispheric functional asymmetry during processing of language,
    intelligence, objects, faces, colors, odors and pheromones.
  • Responses to extreme environmental conditions of hypothermia,
    zero microgravity, and hypergravity
  • Pathology in stroke, epilepsy, hypertension, Alzheimer's disease,
    vascular dementia, autism, traumatic brain injury
  • Pathology resulting from brain-cardiac dysregulation such as in

First in Literature Milestones of the Non-invasive Neurocybernetic
Flow Laboratory

1989 - Development of Phase-contrast Magnetic Resonance Imaging
of Cerebrospinal Fluid Dynamics and Cerebral Venous MR Angiography
American Journal of Neuroradiology. 1989; 10:77-80.

1991- Development of Transcranial Evaluation of Syncope During Head-
down Tilt Testing as a Clinical Method
Aviation Space and Environmental Medicine. 1991; 62:569-572.

1991- Development of Fourier Analysis of Cerebral Vascular System as
an Index of Cerebrovascular Resistance
Stroke. 1991; 22:721-726.

1991- Development of Non-invasive Ultrasound Detection of Language
Processing and Description of the Relationship between Hemispheric
Specialization for Language and Handedness
Brain and Language. 1991; 41:367-380.

1992 - Definition of the Critical limit of Cerebral Blood Flow Velocity for
Maintenance of Human Consciousness
Stroke. 1992 Dec;23(12):1743-7.

1992 - Description of Cerebrovasular Dysautoregulation Syndrome
in a heart-lung transplant recipient.
Journal of Cardiovascular Technology 1992; 10(4):227-232.

1993 - Description of Cerebrovascular Dysautoregulation Syndrome in
a heart transplant recipient.
Pacing and Cardiac Electrophysiology 1993; 16:491-495.

1993 -Description of Cerebral Circulatory Dysfunction in Cerebral
Syncope type I and II.
Canadian Journal of Cardiology 1993; 9(3):238-242.

1993 - Description of Cerebral Circulatory Changes in Pilots During
Pressure Breathing at High-G stress for Simulation of High
Performance Aircraft
Aviation Space and Environmental Medicine. 1993; 64:396-400.

1994 - Visual Cortex Blood Flow in Perceptual and Psychomotor tasks.
National Aeronautic and Space Administration (NASA) and the National
Institutes of Health (NIH).   

2002 - Description of Cerebral Lateralization and Psychomotor
Changes during Simulated Microgravity.  
Journal of Gravitational Physiology 2002 Jul;9(1):P33-4.

2004 - Description of Cerebral Lateralization and Facial Processing
during Simulated Microgravity
Aviation Space and Environmental Medicine 2004; 75:800-5.

2005 - Description of Gender Differences for Tasks of General
Brain and Language 2005 Mar; 92(3):234-9,

2007 - Description of Gender Differences for Facial Processing
Laterality 2007 Jan;12(1):31-49.  


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

Njemanze PC.

Laterality 2007 Jan;12(1):31-49.

Chidicon Medical Center, Owerri, Imo State, Nigeria. philip.

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.

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

Njemanze PC.

Brain and Language 2005 Mar;92(3):234-9.

Non-invasive Neurocybernetic Flow Laboratory, International Institutes
of Advanced Research and Training, Chidicon Medical Center, Owerri,
Imo State, Nigeria.

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.

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

Aviation Space and Environmental Medicine 2004; 75:800 –5.  

Introduction: Ability to interpret facial expression is crucial for nonverbal
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 24HHDR,
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

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

Njemanze PC.

Journal of Gravitational Physiology 2002 Jul;9(1):P33-4.

Non-invsive Neurocybernetic Flow Laboratory, International Institutes of
Advanced Research and Training, Chidicon Medical Center. Owerri,
Imo State, Nigeria.

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.

Crossed aphasia in a dextral with right hemispheric lesion: a functional
transcranial Doppler study.

Njemanze PC.

Stroke 2003 Nov;34(11):e213-4; author reply e213-4.


3D vector component analysis of the modified National Institutes of
Health Neurological Stroke scale.

Njemanze PC, Anozie J, Okadike I.

Stroke. 2001 Dec 1;32(12):2958-60.


Carotid stenosis determines impairment of ipsilateral dexterity in
stroke.  Njemanze PC, Sunderland A.

Stroke. 2000 Feb;31(2):545-6.

Three-dimensional vector component analysis of neurological stroke

Njemanze PC, Chidi-Ebere A.

Stroke. 1999 Aug;30(8):1731-3.

Cerebral lateralization in random letter task in the visual modality: a
transcranial Doppler study.

Njemanze PC.

Brain and Language 1996 Jun;53(3):315-25.

Non-Invasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Imo State, Nigeria.

Seven right handed volunteers were studied to determine cerebral
lateralization patterns for a visually presented random letter task. The
subjects participated in three conditions, which included resting
baseline, passive fixation (nonlinguistic), and random letter (linguistic)
tasks. Mean blood flow velocity (MBFV) was recorded using bilateral
simultaneous transcranial Doppler measurements in the posterior
cerebral arteries in these conditions. The experimental conditions
produced an increase in MBFV during both tasks but the linguistic task
showed a greater change. There was a tendency toward right
lateralization with the linguistic compared to the nonlinguistic tasks.
There is a physiological correlate of right hemisphere participation in
the processing of the random letter task.

Cerebrovascular dysautoregulation syndrome complex--brain
hypoperfusion precedes hypotension and cardiac asystole.

Njemanze PC.

Japanese Circulation Journal. 1994 Apr;58(4):293-7

Noninvasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Owerri Imo State, Nigeria.

A 43-year-old male with history of recurrent episodes of syncope, non-
sustained wide complex tachycardia and structurally normal heart was
studied. Syncope was induced with upright tilt provocation, while
monitoring cerebral blood flow velocity with Doppler ultrasound,
concurrently with invasive blood pressure, heart rate and rhythm
determination. Postural induced cerebral hypoperfusion preceded
hypotension and cardiac asystole. Treatment with ephedrine and
transdermal scopolamine was effective in preventing symptoms.

Perfusion of the visual cortex during pressure breathing at different high-
G stress profiles.

Njemanze PC, Antol PJ, Lundgren CE.

Aviat Space Environ Med. 1993 May;64(5):396-400.

Noninvasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Owerri, Imo State Nigeria.

The effects of pressure breathing for G protection (PBG) on perfusion of
the visual cortex were studied in a subject during various high-G stress
profiles. Blood flow velocity was measured in the posterior cerebral
artery using a transcranial Doppler (TCD) ultrasound instrument. The G
profiles examined included gradual and rapid onset rates. Mean
cerebral blood flow velocity (MCBFV) declined with increasing +Gz with
G-suit protection alone. The MCBFV increased in direct proportion with
increase in +Gz acceleration with PBG. The mediating mechanisms for
the effects of PBG may include improved gaseous exchange, the
diminished sympathicoadrenal discharges, and cardiopulmonary
reflexes. A role for TCD in further research is indicated.

Cerebral circulation dysfunction and hemodynamic abnormalities in
syncope during upright tilt test.

Njemanze PC.

Canadian  Journal of Cardiology. 1993 Apr;9(3):238-42.

Noninvasive Neurocybernetic Flow Laboratory, Chidicon Medical
Centre, Owerri, Imo State, Nigeria.

OBJECTIVE: To assess the hemodynamic features, including
monitoring of cerebral circulation, blood pressure and heart rate, in
syncope patients during upright tilt test. DESIGN: Nonrandomized
sequential patients with history of syncope of uncertain etiology
compared with healthy subjects. SETTING: Noninvasive hemodynamic
laboratory of a tertiary referral centre. PATIENTS: Twenty patients with
history of syncope and 10 controls without syncope. PROCEDURES:
Transcranial Doppler measurement or middle cerebral artery flow
velocity, noninvasive and invasive blood pressure monitoring,
electrocardiography and pulse oximetry monitoring during upright tilt
testing. Measurements were taken in patients at the height of
symptoms in supine and upright posture. MAIN RESULTS: Ten
patients, while still normotensive, had a drop of 53 +/- 10% (mean +/-
SD) in cerebral bloodflow velocity (P = 0.0001) and an increase in heart
rate by 58 +/- 35%. The remaining 10 patients had a 58 +/- 15%
reduction in cerebral bloodflow velocity (P = 0.0001), a drop in blood
pressure of 33 +/- 8% (P = 0.0001) and no change in heart rate. The
controls showed no significant changes in cerebral bloodflow velocity
and a 25 +/- 12% increase in heart rate (P = 0.0002). CONCLUSIONS:
Transcranial Doppler monitoring of cerebral bloodflow velocity during
upright tilt testing may improve insight into the complex physiology of

Isoproterenol induced cerebral hypoperfusion in a heart transplant

Njemanze PC.

Pacing Clinical Electrophysiology. 1993 Mar;16(3 Pt 1):491-5.  

Noninvasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Owerri Imo State, Nigeria.

To determine the effect of tilt isoproterenol provocation on cerebral
perfusion in a patient with denervated heart, transcranial Doppler
sonography was used to assess changes in cerebral blood flow
velocity during upright tilt test. A 51-year-old man with history of
syncopal spells after heart transplantation was evaluated by using
upright tilt test with and without isoproterenol for 30 minutes,
respectively, at 80 degrees inclined. Mean cerebral blood flow was
measured in the main stem of the right middle cerebral artery. Blood
pressure and heart rate were noninvasively monitored. Tilt
isoproterenol provocation but not tilt alone induced a significant
reduction in cerebral blood flow velocity, without remarkable
hypotension. There was no change in respiratory activity. This may
indicate that vagal reflexes are not implicated in the mechanism of
isoproterenol to induce cerebral hypoperfusion and hence neurally
mediated syncope.

Critical limits of pressure-flow relation in the human brain.

Njemanze PC.

Stroke. 1992 Dec;23(12):1743-7.

Noninvasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Owerri, Nigeria.

BACKGROUND: This study was designed to determine the minimal
mean flow velocity and pressure-flow relation necessary to preserve
human consciousness. METHODS: Passive upright tilt provocation was
used in conjunction with transcranial Doppler in 80 patients with a
history of syncope of unknown etiology. Cerebral blood flow velocity,
blood pressure, and heart rate were monitored noninvasively.
RESULTS: Forty patients remained asymptomatic, and the rest had
clinically induced true syncope or premonitory symptoms. In the
asymptomatic group, there was a 23 +/- 16% (p = 0.000) drop in mean
flow velocity, but no significant changes in systolic and diastolic blood
pressures. In the symptomatic patients, there was a 58 +/- 14% (p =
0.000) drop in mean flow velocity, 37 +/- 23% (p = 0.000) fall in systolic
pressure, and 31 +/- 20% (p = 0.000) fall in diastolic pressure. In 80%
of symptomatic patients, the critical lower limit of mean flow velocity
was at -50% of resting baseline while patients were lying supine. The
symptomatic group had lower mean flow velocity and blood pressure
responses as compared with the asymptomatic group. The slope and
intercept values of the pressure (y axis) to flow velocity (x axis)
regression curves indicate a greater degree of impaired autoregulation
in the symptomatic group (y = 0.529 x-6.11, r2 = 0.108, p = 0.038) as
compared with the asymptomatic (y = 0.317 x + 0.966, r2 = 0.14, p =
0.017). CONCLUSIONS: The critical lower limit of cerebral perfusion
lies at 50% below baseline supine mean flow velocity.

Handedness and carotid plaque lesion.

Njemanze PC.

Stroke. 1992 Nov;23(11):1679-80.

Effect of cardiac dysfunction upon diastolic cerebral blood flow.

Gomez CR, McLaughlin JR, Njemanze PC, Nashed A.

Angiology. 1992 Aug;43(8):625-30.

Souers Stroke Institute, Department of Neurology, St. Louis University
Medical Center, Missouri.

The transcranial Doppler (TCD) studies performed in 54 patients with
various forms of cardiac dysfunction were reviewed and the results
compared with those of normal individuals. There were 4 patients with
aortic insufficiency, 5 being treated by intra-aortic balloon pumps, 12
patients with atrial fibrillation, 11 with syncope, and 22 undergoing
cardiopulmonary resuscitation. In all instances, significantly low or even
absent diastolic cerebral perfusion was found. The importance of this
parameter, in the future evaluation and management of similar
patients, is discussed.

Cerebral lateralization and color perception: a transcranial Doppler

Njemanze PC, Gomez CR, Horenstein S.

Cortex. 1992 Mar;28(1):69-75.  

Non-invasive Neurocybernetic Flow Laboratory, Chidicon Medical
Center, Owerri, Imo State, Nigeria.

Eight normal subjects were examined in dark, light and color
conditions. Mean cerebral blood flow velocity (MBFV) were recorded
almost simultaneously from their posterior cerebral arteries (PCA)
using transcranial Doppler (TCD) ultrasound. The side-to-side
difference was significant during the dark (p = 0.0159) and color
stimulation (p = 0.0001) but not in light condition. This side-to-side
difference in MBFV was used to characterize lateralization of color
perception. This showed that the right PCA was always greater than the
left during the presentation of color stimuli. Primary psychological
colors (blue, yellow, red and green) induced greater lateralization as
compared with color resulting from a mixed blue-green wavelength.
This suggests that the right visual cortex is selectively sensitive to

MR-gated intracranial CSF dynamics: evaluation of CSF pulsatile flow.

Njemanze PC, Beck OJ.

AJNR American Journal of Neuroradiology. 1989 Jan-Feb;10(1):77-80.  

Department of Neurosurgery, Clinicum Grosshadern, Ludwig
Maximillians-University, Munich, F.R.G.

This article describes a new imaging method, called MR-gated
intracranial CSF (liquor) dynamics, or MR-GILD. Pulsatile flow in CSF
pathways is revealed by the difference between diastolic- and systolic-
gated images. The images clearly demonstrate the ventricles, cisterns,
and vascular structures. The dependence of CSF movement on arterial
pulse transformation is analyzed, illustrative cases are given to show
some pathologic variations, and the use of MR-GILD for neurosurgical
patients is discussed

Effect of intra-aortic balloon pumps on cerebral circulation.

Gomez CR, McLaughlin JR,
Njemanze PC.

Stroke. 1990 Oct;21(10):1512-3.
Comment on:
Stroke. 1990 Mar;21(3):484-7.

Transcranial Doppler evaluation of syncope: an application in
aerospace physiology.

Njemanze PC.

Aviat Space Environ Med. 1991 Jun;62(6):569-72.  

Non-invasive Flow Neurocybernetic Laboratory, Chidicon Medical
Center, Owerri, Imo State, Nigeria.

A non-invasive method which combines the simultaneous
measurement of mean arterial blood pressure (MBP), heart rate (HR)
and mean cerebral blood flow velocity (MFV) was used to monitor
patients with history of syncope, in horizontal and vertical posture tilt at
80 degrees. MFV in the right middle cerebral artery was measured
using a transcranial Doppler instrument (TCD). MFV decreased
concurrently with the onset of symptoms, and at the time of syncope
reached an average of 68% below pre-tilt values. At the same time MBP
showed an average decline of 25%, and HR increased by 38%. There
was no correlation between MBP and MFV, at the onset of tilt,
presyncope and syncope. MFV, but not HR or MBP, showed significant
transition from one condition to the other. These data suggest that there
may be a useful application of TCD measurements of MFV in
aeromedical evaluation of syncope or syncopal tendency. These
measurements would necessarily be used in conjunction with a tilt-
table procedure. The possibility exists that MFV might be useful to
preclude the actual occurrence of syncope in test subjects, or to show
an abnormal tendency toward syncope, but will require more extensive
testing than that carried out in the present study.

Fourier analysis of the cerebrovascular system.

Njemanze PC, Beck OJ, Gomez CR, Horenstein S.

Stroke. 1991 Jun;22(6):721-6.

Non-invasive Neurocybernetics Flow Laboratory, Chidicon Medical
Center, Owerri, Nigeria.

We performed Fourier analysis of the middle cerebral artery blood flow
velocity waveform envelope in 14 normal subjects (group A) and 15
patients, of whom five had arteriovenous malformations (group B), five
had cerebral vasospasm (group C), and five had arterial hypertension
(group D). Measurements were obtained under conditions of
normocapnia, hypercapnia, and hypocapnia. The Fourier coefficients
measured in the first five harmonics of the Doppler waveforms of group
A were used as the reference baseline and were compared with the
coefficients found in the other three groups. Group B showed
significantly lower Fourier coefficients, while groups C and D showed
higher coefficients (p less than 0.05). The elevation of the Fourier
coefficients occurred in an alternating pattern in group C and a
decremental pattern in group D. This distinction was attributed to
possible differences in the underlying pathophysiological processes.
The degree of vascular distensibility of the cerebral arterioles, inferred
from the shape of the Fourier analysis curves, was compared in all four
groups. Vascular distensibility was characterized as abnormal in
arteriovenous malformations, vasospasm, and arterial hypertension.
Fourier coefficients may be better indicators of cerebrovascular
abnormalities than mean blood flow velocity in hypertension and
pulsatility index in arteriovenous malformations, vasospasm, and

Cerebral lateralization in linguistic and nonlinguistic perception:
analysis of cognitive styles in the auditory modality.

Njemanze PC.

Brain Lang. 1991 Oct;41(3):367-80.  

Non-Invasive Neurocybernetic Flow Laboratory, Chidicon Medical
Center, Owerri, Imo State, Nigeria.

Twenty-two normal subjects (9 left-handers, 13 right-handers) and five
dyslexic patients (3 right-handers, and 2 left-handers) were
characterized by physiologic hemisphere dominance. The latter was
determined by the response of the middle cerebral artery (MCA) blood
flow velocity, measured using the transcranial Doppler (TCD)
technique, to hypoventilation (hypercapnia). Using bilateral almost
simultaneous TCD measurements of mean blood flow velocity in the
MCA, lateralization was determined in response to linguistic and
nonlinguistic paradigms. In relation to the linguistic paradigm, left-
handers, showed lateralization to the physiologic nondominant
hemisphere, while right-handers showed lateralization to the
physiologic dominant hemisphere; dyslexic patients show trends
opposite to those in normals.
Prince Dr Philip C.
Late Prof. William
Bowman Gray
School of Medicine,
Winston Salem
Erwin Koelbl
Mr and Mrs
Andreas Szeibert
St Andrew's Lab
Laboratories and Affiliate Institutes
  • Non-invasive neurocybernetic flow laboratory
  • William McKinney neurosonology laboratory - named to
    honour the memory of Prof. W. McKinney of Bowman Gray
    School of Medicine North Carolina USA.
  • Erwin Koelbl  echocardiography laboratory named after Mr
    Erwin Koelbl of Klinikum Grosshardern, University of
  • St Andrew Biochemistry laboratory
  • Khanna Institute of Advanced Chemistry - named after
    Prof. Raj Khanna of University of Maryland USA.
  • Stroke and hypertension center
  • Institute of Radiological Sciences