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This volume deals with some of the association areas of the
cerebral cortex and with the auditory cortex. In the first chapter,
by Deepak Pandya and Edward Yeterian, the general architectural
features and connections of cortical associ ation areas are
considered; as these authors point out, in primates the association
areas take up a considerable portion of the total cortical surface.
Indeed, it is the development of the association areas that
accounts for the greatest differ ences between the brains of
primate and non primate species, and these areas have long been
viewed as crucial in the formation of higher cognitive and be
havioral functions. In the following chapter, Irving Diamond, David
Fitzpatrick, and James Sprague consider the question of whether the
functions of the as sociation areas depend on projections from the
sensory areas of the cortex. They use the visual cortex to examine
this question and show that there is a great deal of difference
between species in the amount of dependence, the differences being
paralleled by variations in the manner in which the geniculate and
pulvinar nuclei of the thalamus project to the striate and extra
striate cortical areas. One of the more interesting and perhaps
least understood of the association areas is the cingulate cortex,
discussed by Brent Vogt. Cingulate cortex has been linked with
emotion and with affective responses to pain, and in his chapter
Vogt gives an account of its cytoarchitecture, connections, and
functions."
The barrel area is a unique specialization of the cerebral cortex,
shared by many species of rodents and some marsupials, in which the
somatotopic map of the body surface receives direct morphological
expression. Here, the homogeneous sheet of layer IV granule cells
seen in most mammals is fractured into large archipelagos, each
representing one of the larger subdivisions of the contra lateral
half-body. Within these larger domains are smaller aggregates of
granule cells that contain the concentrated terminations of
thalamocortical fibers bear ing messages emanating from
constellations of receptors located in finer subdi visions of a
body part. These smaller aggregates are particularly well-defined
in the representation of the face, where they form a one-to-one
representation of the sinus hairs or vibrissae and where they have
been given the name barrels. The first inklings of the unique
structure of the parietal cortex of rodents came in the study of
Droogleever-Fortuyn (1914), who remarked on the pres ence in it of
clouds of granule cells 0. 5-1 mm in diameter, which he thought
were in some way associated with concentrations of nerve fibers.
Little attention, however, was paid to his observations. Lorente de
N 6 (1922) later observed dense focal concentrations of afferent
fiber ramifications in Golgi preparations of the mouse cortex,
calling them glomeruli, and these can now be seen as the structures
that form the hearts of the barrels and around which the granule
cells concentrate.
The cerebral cortex, especially that part customarily designated
"neocortex," is one of the hallmarks of mammalian evolution and
reaches its greatest size, relatively speaking, and its widest
structural diversity in the human brain. The evolution of this
structure, as remarkable for the huge numbers of neurons that it
contains as for the range of behaviors that it controls, has been
of abiding interest to many generations of neuroscientists. Yet few
theories of cortical evo lution have been proposed and none has
stood the test of time. In particular, no theory has been
successful in bridging the evolutionary gap that appears to exist
between the pallium of nonmammalian vertebrates and the neocortex
of mam mals. Undoubtedly this stems in large part from the rapid
divergence of non mammalian and mammalian forms and the lack of
contemporary species whose telencephalic wall can be seen as having
transitional characteristics. The mono treme cortex, for example,
is unquestionably mammalian in organization and that of no living
reptile comes close to resembling it. Yet anatomists such as Ramon
y Cajal, on examining the finer details of cortical structure, were
struck by the similarities in neuronal form, particularly of the
pyramidal cells, and their predisposition to laminar alignment
shared by representatives of all vertebrate classes."
Volume 2 of Cerebral Cortex continues our policy of dealing with
the individual elements of the cerebral cortex before moving on in
subsequent volumes to a consideration of the details of the various
functional areas. Volume 1 of the treatise dealt with the
morphology of cortical neurons, and Volume 2 continues this theme
to some extent by including chapters devoted to the morphology of
cortical neuroglial cells, of immunocytochemically labeled neurons,
and of in tracellularly i ected neurons. However, the major
emphasis of this volume and of Volume 3, which will follow it, is
on the functional characteristics of cortical neurons and
neuroglial cells, particularly those of transmitter and receptor
iden tity and of electrophysiological uniqueness. Volume 2
emphasizes these char acteristics in relation to the intrinsic
cortical elements; Volume 3 will continue this and add chapters on
the afferent and efferent systems of the cortex. Together, Volumes
2 and 3 will cover all of the transmitters, receptors, and related
compounds that have so far been discovered in the cerebral cortex.
It is the interrelations among the neuronal elements expressing
these materials that determine the functional operations of the
cerebral cortex, and the necessity for understanding how the
appropriate cooperation between the neuronal ele ments is achieved
is highlighted by Sir John C. Eccles's introductory chapter on "The
Cerebral Neocortex: A Theory of Its Operation."
The cerebral cortex, especially that part customarily designated
"neocortex," is one of the hallmarks of mammalian evolution and
reaches its greatest size, relatively speaking, and its widest
structural diversity in the human brain. The evolution of this
structure, as remarkable for the huge numbers of neurons that it
contains as for the range of behaviors that it controls, has been
of abiding interest to many generations of neuroscientists. Yet few
theories of cortical evo lution have been proposed and none has
stood the test of time. In particular, no theory has been
successful in bridging the evolutionary gap that appears to exist
between the pallium of non mammalian vertebrates and the neocortex
of mam mals. Undoubtedly this stems in large part from the rapid
divergence of non mammalian and mammalian forms and the lack of
contemporary species whose telencephalic wall can be seen as having
transitional characteristics. The mono treme cortex, for example,
is unquestionably mammalian in organization and that of no living
reptile comes close to resembling it. Yet anatomists such as Ramon
y Cajal, on examining the finer details of cortical structure, were
struck by the similarities in neuronal form, particularly of the
pyramidal cells, and their predisposition to laminar alignment
shared by representatives of all vertebrate classes.
The previous volumes in this series have dealt with the mature
cerebral cortex. In those volumes many of the structurally and
physiologically distinct areas of the cerebral cortex, their
connections, the various types of neurons and neuroglial cells they
contain, and the functions of those cells have been considered. In
the present volume the contributions focus on the development of
the neocortex and hippocampus. Chapters in this volume describe how
the neurons migrate in the cortex to attain their ultimate
positions, and emphasize the role played by the preexisting pallium
or primordial plexiform layer of the cerebral vesicle in the
development of the cerebral cortex. The primordial plexiform layer
becomes split by the invasion of neurons that will form the
cortical plate, and mutants in which the neuronal migration is
abnormal provide valuable information about the role of the radial
glial cells in this migration. It is also made clear that although
the mechanics of development in the hippocampus are similar to
those in the neocortex, the development of the hippocampus involves
some unique features. For example, neuronal proliferation in the
dentate gyrus continues well into postnatal life.
Volume 6 of Cerebral Cortex is in some respects a continuation of
Volume 2, which dealt with the functional aspects of cortical
neurons from the physiological and pharmacological points of view.
In the current volume, chapters are devoted to the catecholamines,
which for a number of reasons were not represented in the earlier
volume, and to acetylcholine and the neuropeptides, about which
much new information has recently appeared. Volume 6 deals in part
with the structure and function of cholinergic and
catecholaminergic neuronal systems in the cerebral cortex and with
new aspects of the cortical peptidergic neurons, notably the almost
universal propensity of the known cortical peptides for being
colocalized with classical transmitters and with one another. It
thus completes our coverage of the major cortical neuro transmitter
and neuromodulatory systems. Other chapters in this volume deal
with data pertaining to the proportions of different types of cells
and synapses in the neocortex and the physiology of the cortical
neuroglial cells. These latter are topics that rarely receive
separate treatment and the current chapters serve again to continue
discussions of subjects that were introduced in Volume 2. The
previous volumes have all been devoted to the neocortex but the
present one introduces the subject of the archicortex. To this end,
separate chapters are devoted to the physiology and anatomy of the
hippocampal formation."
This volume of the series on "Cerebral Cortex" deals with a variety
of topics that need to be considered in our overall understanding
of the functions of the cerebral hemispheres. Chapters in the first
part of this volume deal with normal functions that were not
covered in earlier volumes, while chapters in the latter part deal
with the functioning of the cortex in various altered states. The
first chapter is by Eberhard Fetz, Keisuke Toyama, and Wade Smith,
and it considers the interactions that can be demonstrated to exist
between cortical neurons by using the technique of
cross-correlation. The second chapter is by Brent Vogt who examines
the connections and functions of layer I of the cerebral cortex, a
layer that has been largely ignored in the past, and he proposes
that this layer probably plays an important role in learning and
memory acquisi tion. This is followed by a chapter in which Oswald
Steward presents a review of what is currently known about synaptic
replacement following denervation of cortical neurons, and
especially those in the hippocampus.
Volume 5 of Cerebral Cortex completes the sequence of three volumes
on the individual functional areas of the cerebral cortex by
covering the somatosensory and motor areas. However, the chapters
on these areas lead naturally to a series of others on patterns of
connectivity in the cortex, intracortical and subcortical, so that
the volume as a whole achieves a much broader viewpoint. The
individual chapters on the sensory-motor areas reflect the
considerable diversity of interest within the field, for each of
the authors has given his or her chapter a different emphasis,
reflecting in part topical interest and in part the body of data
resulting from work in a particular species. In considering the
functional organization of the somatosensory cortex, Robert Dykes
and Andre Ruest have chosen to concentrate on the nature of the
mapping process and its significance. Harold Burton, in his chapter
on the somatosensory fields buried in the sylvian fissure, shows
how critical is an understanding of this mapping process in the
functional subdivision of the cortex. A frequently overlooked
subdivision of the cortex, the vestibular region, is given the
emphasis it deserves in a chapter by John Fredrickson and Allan
Rubin. The further functional subdivisions that occur within the
first somatosensory area are given an anatom ical basis in the
review by Edward Jones of connectivity in the primate sensory motor
cortex."
The barrel area is a unique specialization of the cerebral cortex,
shared by many species of rodents and some marsupials, in which the
somatotopic map of the body surface receives direct morphological
expression. Here, the homogeneous sheet of layer IV granule cells
seen in most mammals is fractured into large archipelagos, each
representing one of the larger subdivisions of the contra lateral
half-body. Within these larger domains are smaller aggregates of
granule cells that contain the concentrated terminations of
thalamocortical fibers bear ing messages emanating from
constellations of receptors located in finer subdi visions of a
body part. These smaller aggregates are particularly well-defined
in the representation of the face, where they form a one-to-one
representation of the sinus hairs or vibrissae and where they have
been given the name barrels. The first inklings of the unique
structure of the parietal cortex of rodents came in the study of
Droogleever-Fortuyn (1914), who remarked on the pres ence in it of
clouds of granule cells 0. 5-1 mm in diameter, which he thought
were in some way associated with concentrations of nerve fibers.
Little attention, however, was paid to his observations. Lorente de
N 6 (1922) later observed dense focal concentrations of afferent
fiber ramifications in Golgi preparations of the mouse cortex,
calling them glomeruli, and these can now be seen as the structures
that form the hearts of the barrels and around which the granule
cells concentrate."
The cerebral cortex, especially that part customarily designated
"neocortex," is one of the hallmarks of mammalian evolution and
reaches its greatest size, relatively speaking, and its widest
structural diversity in the human brain. The evolution of this
structure, as remarkable for the huge numbers of neurons that it
contains as for the range of behaviors that it controls, has been
of abiding interest to many generations of neuroscientists. Yet few
theories of cortical evo lution have been proposed and none has
stood the test of time. In particular, no theory has been
successful in bridging the evolutionary gap that appears to exist
between the pallium of nonmammalian vertebrates and the neocortex
of mam mals. Undoubtedly this stems in large part from the rapid
divergence of non mammalian and mammalian forms and the lack of
contemporary species whose telencephalic wall can be seen as having
transitional characteristics. The mono treme cortex, for example,
is unquestionably mammalian in organization and that of no living
reptile comes close to resembling it. Yet anatomists such as Ramon
y Cajal, on examining the finer details of cortical structure, were
struck by the similarities in neuronal form, particularly of the
pyramidal cells, and their predisposition to laminar alignment
shared by representatives of all vertebrate classes."
Volume 5 of Cerebral Cortex completes the sequence of three volumes
on the individual functional areas of the cerebral cortex by
covering the somatosensory and motor areas. However, the chapters
on these areas lead naturally to a series of others on patterns of
connectivity in the cortex, intracortical and subcortical, so that
the volume as a whole achieves a much broader viewpoint. The
individual chapters on the sensory-motor areas reflect the
considerable diversity of interest within the field, for each of
the authors has given his or her chapter a different emphasis,
reflecting in part topical interest and in part the body of data
resulting from work in a particular species. In considering the
functional organization of the somatosensory cortex, Robert Dykes
and Andre Ruest have chosen to concentrate on the nature of the
mapping process and its significance. Harold Burton, in his chapter
on the somatosensory fields buried in the sylvian fissure, shows
how critical is an understanding of this mapping process in the
functional subdivision of the cortex. A frequently overlooked
subdivision of the cortex, the vestibular region, is given the
emphasis it deserves in a chapter by John Fredrickson and Allan
Rubin. The further functional subdivisions that occur within the
first somatosensory area are given an anatom ical basis in the
review by Edward Jones of connectivity in the primate sensory motor
cortex.
This volume deals with some of the association areas of the
cerebral cortex and with the auditory cortex. In the first chapter,
by Deepak Pandya and Edward Yeterian, the general architectural
features and connections of cortical associ ation areas are
considered; as these authors point out, in primates the association
areas take up a considerable portion of the total cortical surface.
Indeed, it is the development of the association areas that
accounts for the greatest differ ences between the brains of
primate and non primate species, and these areas have long been
viewed as crucial in the formation of higher cognitive and be
havioral functions. In the following chapter, Irving Diamond, David
Fitzpatrick, and James Sprague consider the question of whether the
functions of the as sociation areas depend on projections from the
sensory areas of the cortex. They use the visual cortex to examine
this question and show that there is a great deal of difference
between species in the amount of dependence, the differences being
paralleled by variations in the manner in which the geniculate and
pulvinar nuclei of the thalamus project to the striate and extra
striate cortical areas. One of the more interesting and perhaps
least understood of the association areas is the cingulate cortex,
discussed by Brent Vogt. Cingulate cortex has been linked with
emotion and with affective responses to pain, and in his chapter
Vogt gives an account of its cytoarchitecture, connections, and
functions."
Volumes 8A (43477-6; reviewed in SciTech, March 1991) and 8B, taken
together, set out in some detail the range of telencephalic and
especially cortical structure and connectivity exhibited by the
five major classes of vertebrates. Volume 8A deals largely with
nonmammalian vertebrates. Volume 8B dea
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