Cohen et al. (1997) - Revision history

Rkimchi@rollins.edu at 03:20, 29 April 2008

Rkimchi@rollins.edu — Tue, 29 Apr 2008 03:20:36 GMT

←Older revision		Revision as of 03:20, 29 April 2008
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	'''Functional Relevance of Cross-Modal Plasticity in Blind Humans'''		'''Functional Relevance of Cross-Modal Plasticity in Blind Humans'''
	===Previous Research===		===Previous Research===
-	Imaging studies have shown that the visual cortex can be activated by reading Braille and other tactile tasks, in people who have been blind from an early age.	+	Imaging studies have shown that the [[Primary visual cortex (V1)\|visual cortex]] can be activated by reading Braille and other tactile tasks, in people who have been blind from an early age.

	When applied to the occipital cortex, [[Transcranial magnetic stimulation]] interferes with sight of letters in normal seeing participants		When applied to the occipital cortex, [[Transcranial magnetic stimulation]] interferes with sight of letters in normal seeing participants
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	==Methods==		==Methods==
-	Five experienced Braille readers who had suffered from blindness early in life were asked to read lines of non-word Braille letters (EBB). Five normal sighted participants (SVR) and four early-blind participants (EBR) were asked to identify and read aloud, embossed Roman letters. Their voice was recorded, along with the muscle movements in their hand.	+	Five experienced Braille readers who had suffered from blindness early in life were asked to read lines of non-word Braille letters (EBB). Five normal sighted participants (SVR) and four early-blind participants (EBR) were asked to identify and read aloud, embossed Roman letters. Their voice was recorded, along with the muscle movements in their hand. These were recorded to determine the latency period between feeling the letter and reading it aloud.

	The tasks were performed in the absence of TMS, with the TMS in the air and with the TMS on different areas of the scalp.		The tasks were performed in the absence of TMS, with the TMS in the air and with the TMS on different areas of the scalp.
		+	[[Image:Braille.jpg]]

-	===Results===	+	==Results==
	In the EBB group, occipital stimulation sometimes caused distorted somatosensory perceptions. The participants reported that some dots felt like they were missing, sometimes they felt extra dots, or that the dots did not make sense. Stimulation to the mid-occipital region also caused more errors in both the EBB and EBR group, than when the TMS was in the air. This implies that the occipital cortex is functioning during somatosenosry perception, (not only during Braille reading) of those who have been blind from an early age.		In the EBB group, occipital stimulation sometimes caused distorted somatosensory perceptions. The participants reported that some dots felt like they were missing, sometimes they felt extra dots, or that the dots did not make sense. Stimulation to the mid-occipital region also caused more errors in both the EBB and EBR group, than when the TMS was in the air. This implies that the occipital cortex is functioning during somatosenosry perception, (not only during Braille reading) of those who have been blind from an early age.

	Speech was not affected by any site of TMS, and errors in the speech recordings were attributed to disruption of letter discrimination. Unlike the EBB group, the SVR group did not report distorted perceptions of letters when their occipital cortex was stimulated. This finding indicates that the occipital cortex is not activated when normal sighted people are reading tactile information. When TMS stimulation of the contralateral sensorimotor cortex caused the participants hands to move, the SVR group showed significantly more errors than either EB group. Cohen et al (2007) attributed this finding to their inexperience, suggesting that they may have spent more feeling the letters, making them more vulnerable for the stimulation to affect their reading.		Speech was not affected by any site of TMS, and errors in the speech recordings were attributed to disruption of letter discrimination. Unlike the EBB group, the SVR group did not report distorted perceptions of letters when their occipital cortex was stimulated. This finding indicates that the occipital cortex is not activated when normal sighted people are reading tactile information. When TMS stimulation of the contralateral sensorimotor cortex caused the participants hands to move, the SVR group showed significantly more errors than either EB group. Cohen et al (2007) attributed this finding to their inexperience, suggesting that they may have spent more feeling the letters, making them more vulnerable for the stimulation to affect their reading.

-	===Conclusion===	+	==Conclusion==
	Those who are blind from an early age have plastic changes in their occipital cortex, which allows it to become activated during a tactile task, such as reading Braille or Roman letters.		Those who are blind from an early age have plastic changes in their occipital cortex, which allows it to become activated during a tactile task, such as reading Braille or Roman letters.

Rkimchi@rollins.edu at 03:08, 29 April 2008

Rkimchi@rollins.edu — Tue, 29 Apr 2008 03:08:38 GMT

←Older revision		Revision as of 03:08, 29 April 2008
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	[[Category:Plasticity Symposium]]		[[Category:Plasticity Symposium]]
		+
		+	'''Functional Relevance of Cross-Modal Plasticity in Blind Humans'''
		+	===Previous Research===
		+	Imaging studies have shown that the visual cortex can be activated by reading Braille and other tactile tasks, in people who have been blind from an early age.
		+
		+	When applied to the occipital cortex, [[Transcranial magnetic stimulation]] interferes with sight of letters in normal seeing participants
		+
		+	===Goal of the Current Study===
		+	To examine if the visual cortex can process somatosensory information in a functionally relevant manner.
		+
		+	==Methods==
		+	Five experienced Braille readers who had suffered from blindness early in life were asked to read lines of non-word Braille letters (EBB). Five normal sighted participants (SVR) and four early-blind participants (EBR) were asked to identify and read aloud, embossed Roman letters. Their voice was recorded, along with the muscle movements in their hand.
		+
		+	The tasks were performed in the absence of TMS, with the TMS in the air and with the TMS on different areas of the scalp.
		+
		+	===Results===
		+	In the EBB group, occipital stimulation sometimes caused distorted somatosensory perceptions. The participants reported that some dots felt like they were missing, sometimes they felt extra dots, or that the dots did not make sense. Stimulation to the mid-occipital region also caused more errors in both the EBB and EBR group, than when the TMS was in the air. This implies that the occipital cortex is functioning during somatosenosry perception, (not only during Braille reading) of those who have been blind from an early age.
		+
		+	Speech was not affected by any site of TMS, and errors in the speech recordings were attributed to disruption of letter discrimination. Unlike the EBB group, the SVR group did not report distorted perceptions of letters when their occipital cortex was stimulated. This finding indicates that the occipital cortex is not activated when normal sighted people are reading tactile information. When TMS stimulation of the contralateral sensorimotor cortex caused the participants hands to move, the SVR group showed significantly more errors than either EB group. Cohen et al (2007) attributed this finding to their inexperience, suggesting that they may have spent more feeling the letters, making them more vulnerable for the stimulation to affect their reading.
		+
		+	===Conclusion===
		+	Those who are blind from an early age have plastic changes in their occipital cortex, which allows it to become activated during a tactile task, such as reading Braille or Roman letters.

Admin at 17:45, 20 February 2008

Admin — Wed, 20 Feb 2008 17:45:45 GMT

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