Brain Gyrification and its Significance - Revision history

imported>Psych202 at 07:30, 8 June 2013

2013-06-08T07:30:57Z

imported>Psych202 at 07:15, 8 June 2013

2013-06-08T07:15:25Z

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	There are relativistic terms that describe the extent to which a brain is physically convoluted. These terms often have medical significance.		There are relativistic terms that describe the extent to which a brain is physically convoluted. These terms often have medical significance.
	'''Gyrencephaly''' refers to the condition in which the brain is highly convoluted. This term ~~is really~~ implies a loss function but rather a characterization of species with high gyrification compared to others.		'''Gyrencephaly''' refers to the condition in which the brain is highly convoluted. This term implies a loss function but rather a characterization of species with high gyrification compared to others.
	'''Lissencephaly''', meaning smooth brain, can be described as the condition in which a brain is less gyrified than normal and has medical consequences. In most cases it is a result of a failure of neuronal migration in development		'''Lissencephaly''', meaning smooth brain, can be described as the condition in which a brain is less gyrified than normal and has medical consequences. In most cases it is a result of a failure of neuronal migration in development
	<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.		<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.

imported>Psych202 at 07:11, 8 June 2013

2013-06-08T07:11:28Z

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	Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence due to the gender differences, however, it at least appears to be implicated in females and in the temporo-occiptal lobe.		Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence due to the gender differences, however, it at least appears to be implicated in females and in the temporo-occiptal lobe.

	[[Image: Genderbrain.png\|thumb\|~~500px~~\|~~center~~\| '''Figure 5:''' Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]		[[Image: Genderbrain.png\|thumb\|700px\|right\| '''Figure 5:''' Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]

	==Gyrification in Meditation Practitioners==		==Gyrification in Meditation Practitioners==

imported>Psych202 at 07:10, 8 June 2013

2013-06-08T07:10:34Z

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	Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).		Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).

	[[Image:brainsizebodysize.png\|thumb\|~~300px~~\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|500px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

imported>Psych202 at 07:09, 8 June 2013

2013-06-08T07:09:46Z

← Older revision		Revision as of 07:09, 8 June 2013
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	Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).		Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).

	[[Image:brainsizebodysize.png\|thumb\|300px\|~~right~~ \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|300px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

	[[Image:Eqacrossspecies.png\|thumb\|300px\| ~~right~~\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]		[[Image:Eqacrossspecies.png\|thumb\|300px\| center\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]

	==Gyrification Across Species==		==Gyrification Across Species==

imported>Psych202 at 07:09, 8 June 2013

2013-06-08T07:09:07Z

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	However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.		However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.

	[[Image: clinicalbrain.png\|thumb\|300px\|~~right~~ \| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]		[[Image: clinicalbrain.png\|thumb\|300px\|left \| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]

imported>Psych202 at 07:08, 8 June 2013

2013-06-08T07:08:35Z

imported>Psych202 at 07:06, 8 June 2013

2013-06-08T07:06:47Z

← Older revision		Revision as of 07:06, 8 June 2013
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	<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.		<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.

	[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| ~~right~~\| Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]		[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| center\| Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]

	==Nuanced Convolutions==		==Nuanced Convolutions==
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	However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.		However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.

	[[Image: clinicalbrain.png\|thumb\|300px\|~~right~~\| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]		[[Image: clinicalbrain.png\|thumb\|300px\|center\| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]

imported>Psych202: /* Gyrification and Intelligence: Effects are Different Across Genders */

2013-06-08T07:06:21Z

Gyrification and Intelligence: Effects are Different Across Genders

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	Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence due to the gender differences, however, it at least appears to be implicated in females and in the temporo-occiptal lobe.		Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence due to the gender differences, however, it at least appears to be implicated in females and in the temporo-occiptal lobe.

	[[Image: Genderbrain.png\|thumb\|500px\|center\| ""Figure 5:"" Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]		[[Image: Genderbrain.png\|thumb\|500px\|center\| '''Figure 5:''' Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]

	==Gyrification in Meditation Practitioners==		==Gyrification in Meditation Practitioners==

imported>Psych202: /* Gyrification Across Species */

2013-06-08T07:05:42Z

Gyrification Across Species

← Older revision		Revision as of 07:05, 8 June 2013
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	[[Image: ~~Eqacrossspecies~~.png\|thumb\|500px\|center\| ""Figure 4:"" Gyrification to Brain Mass Comparison. Credit: Manger, 2012.]]		[[Image: oops.png\|thumb\|500px\|center\| '''Figure 4:''' Gyrification to Brain Mass Comparison. Credit: Manger, 2012.]]

	=Mechanism of Folding=		=Mechanism of Folding=

← Older revision		Revision as of 07:10, 8 June 2013
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	Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).		Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).

	[[Image:brainsizebodysize.png\|thumb\|~~300px~~\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|500px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

← Older revision		Revision as of 07:09, 8 June 2013
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	Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).		Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).

	[[Image:brainsizebodysize.png\|thumb\|300px\|~~right~~ \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|300px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

	[[Image:Eqacrossspecies.png\|thumb\|300px\| ~~right~~\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]		[[Image:Eqacrossspecies.png\|thumb\|300px\| center\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]

	==Gyrification Across Species==		==Gyrification Across Species==

← Older revision		Revision as of 07:30, 8 June 2013
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	Gyrification in the brain, also known as convolution, is process of cortical folding that leads to the wrinkle like appearance of mammal brains. It is the basis for the presence of gyri and sulci (hills and valleys) in cerebral cortex. The extent of gyrification of brains is highly implicated as being positively related to species intelligence. The basic idea is that gyrification allows for (or is a result of) greater surface area of cortical neurons within the same skull volume. However the exact mechanism by which this occurs, its true significance, and the implications of differences within species is not conclusively known or explored. With this in mind, this wiki seeks to explore the literature on the chemical or physical cause/mechanism of gyrification, differences in anatomy across species and within species, and possible theories of significance that could be derived based on previous findings.		Gyrification in the brain, also known as convolution, is a process of cortical folding that leads to the wrinkle like appearance of mammal brains. It is the basis for the presence of gyri and sulci (hills and valleys) in cerebral cortex. The extent of gyrification of brains is highly implicated as being positively related to species intelligence. The basic idea is that gyrification allows for (or is a result of) greater surface area of cortical neurons within the same skull volume. However the exact mechanism by which this occurs, its true significance, and the implications of differences within species is not conclusively known or explored. With this in mind, this wiki seeks to explore the literature on the chemical or physical cause/mechanism of gyrification, differences in anatomy across species and within species, and possible theories of significance that could be derived based on previous findings.

	=Classification and Medical Terminology=		=Classification and Medical Terminology=
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	There are relativistic terms that describe the extent to which a brain is physically convoluted. These terms often have medical significance.		There are relativistic terms that describe the extent to which a brain is physically convoluted. These terms often have medical significance.
	'''Gyrencephaly''' refers to the condition in which the brain is highly convoluted. This term ~~implies~~ a loss function but rather a characterization of species with high gyrification compared to others.		'''Gyrencephaly''' refers to the condition in which the brain is highly convoluted. This term does not imply a loss of function, but rather a characterization of species with high levels of gyrification compared to others.
	'''Lissencephaly''', meaning smooth brain, can be described as the condition in which a brain is less gyrified than normal and has medical consequences. In most cases it is a result of a failure of neuronal migration in development		'''Lissencephaly''', meaning smooth brain, can be described as the condition in which a brain is less gyrified than normal and this has medical consequences. In most cases, it is a result of a failure of neuronal migration in development
	<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.		<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays <sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''', meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.

	[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| right Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]		[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| right Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]
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	==Nuanced Convolutions==		==Nuanced Convolutions==

	However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.		However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''', for example, is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.

	[[Image: clinicalbrain.png\|thumb\|300px\|left \| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]		[[Image: clinicalbrain.png\|thumb\|300px\|left \| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]
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	==Brain Size to Body Weight Ratios Across Species==		==Brain Size to Body Weight Ratios Across Species==

	Before ~~doing~~ analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size ~~increases~~ absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (~~dumb~~ for body size).		Before analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains increase in size absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (unintelligent for body size).

	[[Image:brainsizebodysize.png\|thumb\|500px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|500px\|center \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass ~~vs.~~ the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which is a quantitative measure of the relative brain size based on actual brain mass versus the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

	[[Image:Eqacrossspecies.png\|thumb\|300px\| center\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]		[[Image:Eqacrossspecies.png\|thumb\|300px\| center\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]
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	=Differences in Gyrification across Humans=		=Differences in Gyrification across Humans=

	Gyrification is a process that has predictable benchmarks in human fetal development. ~~Often~~ a phenotype of several mental disorders ~~are abnormal phenotypes of cerebral convolution development~~ <sup>[[Brain_Gyrification_and_its_Significance#References\|[10]]]</sup>. Differences in gyrification across humans is often associated with such disorders, but there is also some literature on gyrification differences across age, gender, and other groups in normal and healthy humans.		Gyrification is a process that has predictable benchmarks in human fetal development. Abnormal cerebral convolution development is often a phenotype of several mental disorders <sup>[[Brain_Gyrification_and_its_Significance#References\|[10]]]</sup>. Differences in gyrification across humans is often associated with such disorders, but there is also some literature on gyrification differences across age, gender, and other groups in normal and healthy humans.

	==Gyrification and Aging==		==Gyrification and Aging==

	It has been shown that as humans age, the cortex becomes progressively thinner, and the degree of gyri and sulci curvature changes such that cortex appears to become more atrophic <sup>[[Brain_Gyrification_and_its_Significance#References\|[10]]]</sup>.These features are associated with less cortical neurons which we may associate with a reduction in cognitive function or less ambitiously, the pruning of neurons.		It has been shown that as humans age, the cortex becomes progressively thinner, and the degree of gyri and sulci curvature changes such that the cortex appears to become more atrophic <sup>[[Brain_Gyrification_and_its_Significance#References\|[10]]]</sup>.These features are associated with less cortical neurons which we may associate with a reduction in cognitive function or less ambitiously, the pruning of neurons.

	==Gyrification and Intelligence: Effects are Different Across Genders==		==Gyrification and Intelligence: Effects are Different Across Genders==

	Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence due to the gender differences~~, however~~, it at least appears to be implicated in females and in the temporo-occiptal lobe.		Luders (2007) showed that intelligence scores were positively associated with the degree of folding in the temporo-occiptal lobe. Furthermore, greater gyrification in the frontal cortex of females was correlated with higher IQ, while less convolution in frontal cortex of males was associated with lower IQ <sup>[[Brain_Gyrification_and_its_Significance#References\|[11]]]</sup>. '''See Figure 5'''. These mixed results might make any official statement about whether greater gyrification in normal humans can be positively correlated to intelligence invalid due to the gender differences. However, it at least appears to be implicated in females and in the temporo-occiptal lobe for both genders.

	[[Image: Genderbrain.png\|thumb\|700px\|right\| '''Figure 5:''' Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]		[[Image: Genderbrain.png\|thumb\|700px\|right\| '''Figure 5:''' Correlations between Cortical Convolution and IQ. Credit: Luders, 2007]]
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	==Gyrification and Disorder==		==Gyrification and Disorder==

	Abnormalities in gyrification have been implicated in autism spectrum disorders, schizophrenia, Williams syndrome, and severe disorders of neuronal migration (e.g. Reelin gene mutation) <sup>[[Brain_Gyrification_and_its_Significance#References\|[13, 14]]]</sup>. Uniquely though, the findings in autism spectrum disorder involve comparable surface area yet increased gyrification <sup>[[Brain_Gyrification_and_its_Significance#References\|[15]]]</sup>. One theory of autism argues that it involves atypical excessively early brain development, which negatively affects normal learning but sometimes involves savant like abilities in very specific cognitive tasks. Perhaps greater gyrification in specific regions of the brain account of savant like abilities.		Abnormalities in gyrification have been implicated in autism spectrum disorders, schizophrenia, Williams syndrome, and severe disorders of neuronal migration (e.g. Reelin gene mutation) <sup>[[Brain_Gyrification_and_its_Significance#References\|[13, 14]]]</sup>. Uniquely though, the findings in autism spectrum disorder involve comparable surface area yet increased gyrification <sup>[[Brain_Gyrification_and_its_Significance#References\|[15]]]</sup>. One theory of autism argues that it involves atypical excessively early brain development, which negatively affects normal learning and development but sometimes involves savant like abilities in very specific cognitive tasks. Perhaps greater gyrification in specific regions of the brain account for savant like abilities.

	=Conclusion and Future Directions=		=Conclusion and Future Directions=
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	However whether somehow increasing the gyrification or surface area of a cortex within a species would be related to increased intelligence is still up for debate. Though higher IQ was correlated with greater convolution in females, an opposite effect was found in males. No genes have been associated with increasing gyrification; only loss of function in certain genes has been shown to exhibit negative and abnormal convulutions (Lissencephaly).		However whether somehow increasing the gyrification or surface area of a cortex within a species would be related to increased intelligence is still up for debate. Though higher IQ was correlated with greater convolution in females, an opposite effect was found in males. No genes have been associated with increasing gyrification; only loss of function in certain genes has been shown to exhibit negative and abnormal convulutions (Lissencephaly).
	The studies on meditation and autism could be further explored to more conclusively answer the question of whether positive modulation of gyrification within the human species could equate higher intelligence. Since insula gyrification increased in meditators, perhaps the same meditators could undergo paradigns of cognitive tasks previously shown to be associated with insula function; higher performance in these tasks would suggest that greater gyrification is associated with higher cognition. One could also look at autistic savants to see if areas of their brain associated with any unique abilities they may have are more convoluted (e.g. savant who visually sees every detail or hears every ~~sound~~ having increased convolutions in visual or audio cortex respectively) If ~~it would~~ it were one day possible to have some sort of pharmacological or gene therapy treatment that was shown to increase the number of cortical neurons, it would be interesting to see gyrification and IQ increased. This would conclusively show that the physical tension based model of gyrification is correct and that gyrification is a strong correlate of cognitive ability.		The studies on meditation and autism could be further explored to more conclusively answer the question of whether positive modulation of gyrification within the human species could equate higher intelligence. Since insula gyrification increased in meditators, perhaps the same meditators could undergo paradigns of cognitive tasks previously shown to be associated with insula function; higher performance in these tasks would suggest that greater gyrification is associated with higher cognition (at least insular cognition). One could also look at autistic savants to see if areas of their brain associated with any unique abilities they may have are more convoluted (e.g. savant who visually sees every detail or hears every frequency having increased convolutions in visual or audio cortex respectively). If it were one day possible to have some sort of pharmacological or gene therapy treatment that was shown to increase the number of cortical neurons, it would be interesting to see gyrification and IQ increased. This would conclusively show that the physical tension based model of gyrification is correct and that gyrification is a strong correlate of cognitive ability.

← Older revision		Revision as of 07:08, 8 June 2013
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	<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.		<sup>[[Brain_Gyrification_and_its_Significance#References\|[1]]]</sup> and results in mental retardation and severe developmental delays (<sup>[[Brain_Gyrification_and_its_Significance#References\|[2]]]</sup>. Causes may be viral or genetic <sup>[[Brain_Gyrification_and_its_Significance#References\|[3]]]</sup>. Its most extreme form is '''Argyria''' meaning no gyri. This condition may begin to hint at what the mechanism for the folding is and its role in intelligence.

	[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| ~~center\|~~ Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]		[[Image: Lissencephaly-Image.jpg\|thumb\|350px\| right Lissencephaly vs. Normal Brain. Source: http://www.hxbenefit.com/lissencephaly.html]]

	==Nuanced Convolutions==		==Nuanced Convolutions==
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	However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.		However, there are different types of gyrification phenotypes that seem to complicate the intuition that the magnitude of gyrification alone is related to intelligence; brains with reasonable amounts of gyrification but different gyri shapes have unfavorable consequences. '''Pachygyria''' for example is malformation involving unusually thick convolutions. '''Polymicrogyria''' is a malformation involving an excess number of smaller gyri. Both are associated with developmental delays.

	[[Image: clinicalbrain.png\|thumb\|300px\|~~center~~\| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]		[[Image: clinicalbrain.png\|thumb\|300px\|right \| Left to Right: normal, polymicrogyria, lissencephaly. Credit: Lefèvre and Mangin, 2010l]]


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	Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).		Before doing analyzing cross species comparisons of gyrification, it is important to note that the ratio of brain size to body weight was one of the original and more salient topics regarding how physiological differences in brains may predict differences in intelligence across species. '''Figure 1''' shows a relationship between brain size and body size; as the weight/size of a species increases, brains size increases absolutely, but are relatively smaller <sup>[[Brain_Gyrification_and_its_Significance#References\|[4]]]</sup>. The relative intelligence of species is considered related to how high above or below the best fit line a species is. For example, man and dolphin in the graph are “above” the best fit line (smart species for given body size) while pigs and hippos are below (dumb for body size).

	[[Image:brainsizebodysize.png\|thumb\|300px\|~~center~~\|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]		[[Image:brainsizebodysize.png\|thumb\|300px\|right \|'''Figure 1:''' Relationship between brain size and body size in selected mammals. Credit: Roth & Dicke, 2005]]

	A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.		A better of way of looking at this data is with what is known as the '''Encephalization Quotient (EQ)''', which a quantitative measure of the relative brain size based on brain mass vs. the predicted brain mass of an animal of a given size. '''Figure 2''' features a table of species and their EQ values as shown by Macphail <sup>[[Brain_Gyrification_and_its_Significance#References\|[5]]]</sup>. In general, these values agree with well established findings that primates, cetaceans (the family dolphins are in), and elephants have notably high cognitive abilities in the animal world <sup>[[Brain_Gyrification_and_its_Significance#References\|[6]]]</sup>.

	[[Image:Eqacrossspecies.png\|thumb\|300px\|~~center~~\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]		[[Image:Eqacrossspecies.png\|thumb\|300px\| right\|'''Figure 2:''' EQ Values Across Species. Credit: Macphail]]

	==Gyrification Across Species==		==Gyrification Across Species==

	[[Image: species gyrification.jpg\|thumb\|500px\|~~center~~\| ""Figure 3:"" Gyrification Across Species. Credit to Patricia Anne Kinser (2000). Source: http://serendip.brynmawr.edu/exchange/brains]]		[[Image: species gyrification.jpg\|thumb\|500px\|right\| ""Figure 3:"" Gyrification Across Species. Credit to Patricia Anne Kinser (2000). Source: http://serendip.brynmawr.edu/exchange/brains]]

	The same species we intuitively consider more intelligent that already were shown to a greater relative brain size to body weight ratio also show similar trends in gyrification. Figure 3 shows clear anatomical distinctions in the extent of convolution across species in a manner we would expect. This can also be looked at quantitatively; Figure 4 feature a relationship of Gyrencephalic Index to Brain mass; Cetaceans feature significantly higher ratios <sup>[[Brain_Gyrification_and_its_Significance#References\|[7]]]</sup>. These findings suggest that gyrification has fair cause to be associated with intelligence.		The same species we intuitively consider more intelligent that already were shown to a greater relative brain size to body weight ratio also show similar trends in gyrification. Figure 3 shows clear anatomical distinctions in the extent of convolution across species in a manner we would expect. This can also be looked at quantitatively; Figure 4 feature a relationship of Gyrencephalic Index to Brain mass; Cetaceans feature significantly higher ratios <sup>[[Brain_Gyrification_and_its_Significance#References\|[7]]]</sup>. These findings suggest that gyrification has fair cause to be associated with intelligence.


	[[Image: oops.png\|thumb\|500px\|~~center~~\| '''Figure 4:''' Gyrification to Brain Mass Comparison. Credit: Manger, 2012.]]		[[Image: oops.png\|thumb\|500px\|right\| '''Figure 4:''' Gyrification to Brain Mass Comparison. Credit: Manger, 2012.]]

	=Mechanism of Folding=		=Mechanism of Folding=