Up till now, it was well known
that bats, whales and many other praying mantises make use of ultrasound to
guide them and sense the movement and presence of their prey. However, William "Jamie" Tyler, an
assistant professor at the Virginia Tech Carilion Research Institute and his
colleagues, have presented a new study that shows that ultrasound can even modulate brain activity and heighten sensory perception in humans. When directed to a specific region of a brain: Transcranial region in low intensity, ultrasound can enhance performance in sensory discrimination. This study has been published online in Nature Neuroscience.
Scientists of Virginia Tech
Carilion Research Institute analysed the effects of ultrasound on that region
of brain which is responsible for dealing with tactile sensory inputs since Ultrasound has great
potential for bringing resolution to the mapping of human brain's connectivity
A focused ultrasound was delivered to an area of the cerebral
cortex that processes sensory information received from the hand. A median
nerve is a major nerve that runs down the arm as it is the only one that passes
through the carpal tunnel. A small electrode was placed on the wrist of human
volunteers and their brain responses were recorded using
electroencephalography, or EEG. Before stimulating median nerve, ultrasound was
directed to target region of brain.
It was observed that EEG signal decreased and brain waves
responsible for encoding tactile stimulation were also weakened due to
ultrasound.
The scientists then administered two classic neurological tests:
1) The two-point
discrimination test, which analyses a subject's ability to distinguish whether
two close by objects touching the skin are two distinct points, rather than
one;
2) The frequency
discrimination task, a test that measures sensitivity to the frequency of a
chain of air puffs.
Results were unexpected.
The subjects that received
ultrasound showed improvements in their ability to distinguish pins at nearer
distances and also discriminated small frequency differences between successive
air puffs.
Suppression of brain responses to sensory stimulation heightens
perception. Thus, ultrasound affected an important neurological balance. Tyler
explained that this is due to the fact that the particular ultrasound waveform used
in the study alters the balance of synaptic inhibition and excitation between
neighboring neurons within the cerebral cortex. Focused ultrasound changed the
balance of ongoing excitation and inhibition processing sensory stimuli in the
brain region targeted and this shift prevented the spatial spread of excitation
in response to stimuli resulting in a functional improvement in perception.
When the acoustic beam was moved one centimeter in either directions of the
original site of brain stimulation, it was seen that effect disappeared.
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This discovery represents a new way of
noninvasively modulating human brain activity with a better spatial resolution
than anything currently existing: Transcranial magnetic stimulation, which uses
magnets to activate the brain, and Transcranial direct current stimulation,
which uses weak electrical currents delivered directly to the brain through
electrodes placed on the head.This will further enhance mapping of the richly interconnected synaptic circuits in human brain. Moreover, work is going on to extend the capabilities of ultrasound for non-invasively tweaking brain circuits to help us understand how human brain works.
Up till now, it was well known
that bats, whales and many other praying mantises make use of ultrasound to
guide them and sense the movement and presence of their prey. However, William "Jamie" Tyler, an
assistant professor at the Virginia Tech Carilion Research Institute and his
colleagues, have presented a new study that shows that ultrasound can even modulate brain activity and heighten sensory perception in humans. When directed to a specific region of a brain: Transcranial region in low intensity, ultrasound can enhance performance in sensory discrimination. This study has been published online in Nature Neuroscience.
Scientists of Virginia Tech
Carilion Research Institute analysed the effects of ultrasound on that region
of brain which is responsible for dealing with tactile sensory inputs since Ultrasound has great
potential for bringing resolution to the mapping of human brain's connectivity
A focused ultrasound was delivered to an area of the cerebral
cortex that processes sensory information received from the hand. A median
nerve is a major nerve that runs down the arm as it is the only one that passes
through the carpal tunnel. A small electrode was placed on the wrist of human
volunteers and their brain responses were recorded using
electroencephalography, or EEG. Before stimulating median nerve, ultrasound was
directed to target region of brain.
It was observed that EEG signal decreased and brain waves
responsible for encoding tactile stimulation were also weakened due to
ultrasound.
The scientists then administered two classic neurological tests:
1) The two-point
discrimination test, which analyses a subject's ability to distinguish whether
two close by objects touching the skin are two distinct points, rather than
one;
2) The frequency
discrimination task, a test that measures sensitivity to the frequency of a
chain of air puffs.
Results were unexpected.
The subjects that received
ultrasound showed improvements in their ability to distinguish pins at nearer
distances and also discriminated small frequency differences between successive
air puffs.
Suppression of brain responses to sensory stimulation heightens
perception. Thus, ultrasound affected an important neurological balance. Tyler
explained that this is due to the fact that the particular ultrasound waveform used
in the study alters the balance of synaptic inhibition and excitation between
neighboring neurons within the cerebral cortex. Focused ultrasound changed the
balance of ongoing excitation and inhibition processing sensory stimuli in the
brain region targeted and this shift prevented the spatial spread of excitation
in response to stimuli resulting in a functional improvement in perception.
When the acoustic beam was moved one centimeter in either directions of the
original site of brain stimulation, it was seen that effect disappeared.
This discovery represents a new way of
noninvasively modulating human brain activity with a better spatial resolution
than anything currently existing: Transcranial magnetic stimulation, which uses
magnets to activate the brain, and Transcranial direct current stimulation,
which uses weak electrical currents delivered directly to the brain through
electrodes placed on the head.This will further enhance mapping of the richly interconnected synaptic circuits in human brain. Moreover, work is going on to extend the capabilities of ultrasound for non-invasively tweaking brain circuits to help us understand how human brain works.
