Intracranial Cerebrovascular Ultrasound Examination Techniques

Alexandrov, Andrei V.; Neumyer, Marsha M.

doi:10.1002/9780470752883.ch2

Cited by 14 publications

(13 citation statements)

References 24 publications

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“…Other transmit parameters are not reported by this commercial machine. The depth was initially set to expected depths for the MCA, based on published values [28], and the strongest signal was found by manual adjustment of the depth and transducer position. (The resulting depth ranged from 43 to 55 mm and gate size from 8 to 10 mm, with power set at 420 mW/cm 2 .)…”

Section: Methodsmentioning

confidence: 99%

Functional Transcranial Doppler Ultrasound for Measurement of Hemispheric Lateralization During Visual Memory and Visual Search Cognitive Tasks

Hage

Alwatban

Barney

et al. 2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Functional transcranial Doppler ultrasound (fTCD) is a noninvasive sensing modality that measures cerebral blood flow velocity (CBFV) with high temporal resolution. CBFV change is correlated to changes in cerebral oxygen uptake, enabling fTCD to measure brain activity and lateralization with high accuracy. However, few studies have examined the relationship of CBFV change during visual search and visual memory tasks. Here a protocol to compare lateralization between these two similar cognitive tasks using fTCD is demonstrated. Ten healthy volunteers (age 21±2 years) were shown visual scenes on a computer and performed visual search and visual memory tasks while CBFV in the bilateral middle cerebral arteries was monitored with fTCD. Each subject completed 40 trials, consisting of baseline (25 s), calibration (variable), instruction (2.5 s), and task (20 s) epochs. Lateralization was computed for each task by calculating the bilateral CBFV envelope percent change from baseline and subtracting the right side from the left side. The results showed significant lateralization (p < 0.001) of the visual memory and visual search tasks, with memory reaching lateralization of 1.6% and search reaching lateralization of 0.5%, suggesting that search is more right lateralized (and therefore may be related to “holistic” or global perception) and memory is more left lateralized (and therefore may be related to local perception). This method could be used to compare cerebral activity for any related cognitive tasks as long as the same stimulus is used in all tasks. The protocol is straightforward and the equipment is inexpensive, introducing a low-cost high temporal resolution technique to further study lateralization of the brain.

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Section: Methodsmentioning

confidence: 99%

Functional Transcranial Doppler Ultrasound for Measurement of Hemispheric Lateralization During Visual Memory and Visual Search Cognitive Tasks

Hage

Alwatban

Barney

et al. 2016

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…In our study we failed to eliminate a mathematical error associated with the measurement of the MCA diameters [8, 15].…”

Section: Discussionmentioning

confidence: 99%

“…DHCTA was performed of 16 volume of the data, 160 mm in thickness, within 60 s with a contrast agent (Ultravist 370, Schering, Germany) administered [7], During or immediately after DHCTA the monitoring of the transcranial Doppler (TCD) of the MCA was recorded bilaterally with 2-MHz probes within 10 minutes [8],…”

Section: Methodsmentioning

confidence: 99%

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Cerebral Arterial Compliance in Traumatic Brain Injury

Dobrzeniecki

Trofimov

Bragin

2017

Acta Neurochirurgica Supplement

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“…The depth setting on the TCD was initially set to expected depths for the MCA based on published values (Alexandrov & Neumyer, 2004), and the strongest signal was found by manual adjustment of the depth and transducer position. Accordingly, the MCAs were insonated at depths between 43 and 55 mm, with Doppler gate size between 8 and 10 mm.…”

Section: Methodsmentioning

confidence: 99%

Cerebral hemodynamics during scene viewing: Hemispheric lateralization predicts temporal gaze behavior associated with distinct modes of visual processing.

Mills

Alwatban

Hage

et al. 2017

Journal of Experimental Psychology: Human Perception and Perfor

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Systematic patterns of eye movements during scene perception suggest a functional distinction between two viewing modes: an ambient mode (characterized by short fixations and large saccades) thought to reflect dorsal activity involved with spatial analysis, and a focal mode (characterized by long fixations and small saccades) thought to reflect ventral activity involved with object analysis. Little neuroscientific evidence exists supporting this claim. Here, functional transcranial Doppler ultrasound was used to investigate whether these modes show hemispheric specialization. Participants viewed scenes for 20 seconds under instructions to search or memorize. Overall, early viewing was right lateralized, whereas later viewing was left lateralized. This right-to-left shift interacted with viewing task (more pronounced in the memory task). Importantly, changes in lateralization correlated with changes in eye movements. This is the first demonstration of right hemisphere bias for eye movements servicing spatial analysis and left hemisphere bias for eye movements servicing object analysis.

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Intracranial Cerebrovascular Ultrasound Examination Techniques

Cited by 14 publications

References 24 publications

Functional Transcranial Doppler Ultrasound for Measurement of Hemispheric Lateralization During Visual Memory and Visual Search Cognitive Tasks

Functional Transcranial Doppler Ultrasound for Measurement of Hemispheric Lateralization During Visual Memory and Visual Search Cognitive Tasks

Cerebral Arterial Compliance in Traumatic Brain Injury

Cerebral hemodynamics during scene viewing: Hemispheric lateralization predicts temporal gaze behavior associated with distinct modes of visual processing.

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