age related changes in regional cerebral blood volume

8/2/2019 Age Related Changes in Regional Cerebral Blood Volume

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Click to edit Master subtitle style

3/22/12

Age RelatedChanges in Regional

Cerebral Blood

Volume

Dr.Rajath


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What they mean..


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Dentulous PatientsRecent studies have shown that chewing is associated withactivation of various brain regions including the prefrontal

cortex.

Wilkinson et al. showed that gum chewing could lead to

improved performance. In addition, gum chewing appeared to

improve both spatial and numeric working memory. Baker et al.

reported that gum chewing during encoding a word list

improved their recall performance. It was also noted that gum

chewing appeared to be of benefit to verbal working memory,

immediate episodic long term memory, language-based

attention and probing speed.

However, the processes underlying these chewing effects


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Stephens and Tunney reported that gum chewing leads

to cognitive benefits through improved delivery of

glucose to the brain, but

that some other mechanism is more likely to underlie

the facilitatory

effect of gum chewing on delayed episodic long-term

memory.

Recently, fMRI has become a useful tool for the

estimation of chewing effects, whereby it has been

reported that chewing activates various regions


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Yoshiyuki Hirano- Neuroscience Letters

v38 right handed healthy volunteers(aged 20-39)

vTwo- and three- back(n-back) tasks with different

loads for the working memory task used.

vN-back test- continuous stream of 15 single letters

chosen at randoms.

v

fMRI task paradigm- four trials; [practice] [Before 1st][Before 2nd] [After]


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Onozuka, et al-2002

v17 subjects aged 20-31yrs.

vResults suggest that chewing causes regional

increases in brain neuronal activities which are related

to biting force.

vTwo types of gum-hard(G type) and moderately hard(X

type) were used.

vTask paradigm-rhythmic chewing @ 1Hz, 4cycles of

32sec of rhythmic chewing and 32 sec without

chewing.

vfMRI done.


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In all subjects, gum-chewing was associated with

significant increases in the BOLD signal in various

regions of the brain. The primary sensorimotor cortex

was strongly activated by chewing. Also, mastication

of moderately hard food leads to a greater increase in

cerebral blood flow than that of soft and/or hard food.

This suggests that chewing with a moderate biting

force may be most effective in maintaining neuronal

activity within the brain.


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Momose, et al 1996

vMultidisciplinary study

v12 volunteers(18-40yrs)

vTask paradigm-4 brain scans every 15 min during four

tasks-rest, whilst chewing gum base, at rest 15 min

after stopping chewing, at rest 30 min after stopping

chewing. Chewing task began 60 sec before tracer

injection and contd throughout the scanning period.

vWater labelled with oxygen-15 (H215O) injected to

median cubital vein as bolus in 2ml saline with total

dose of 1850 MBq


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age related changes in regional cerebral blood volume

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