Cristian Company Font - Academia.edu (original) (raw)

Papers by Cristian Company Font

Research paper thumbnail of Catecholaminergic interplexiform cells in the retina of lizards

Vision Research, 1996

An immunohistochemical study of the distribution of tyrosine hydroxylase has been performed in th... more An immunohistochemical study of the distribution of tyrosine hydroxylase has been performed in the retina of lizards of the genera Podarcis, Anolis and Tarentola. Immunoreactive cells extending their processes into the inner plexiform layer were observed in all three species. Reactive fibres in the outer plexiform layer were also seen in Podarcis and Anolis, and hence they possess not only amacrine but also catecholaminergic interplexiform cells. The retina of Anolis also showed reactive fibres aposed to the photoreceptors near the central fovea. The role of this outer retinal innervation on dopamine.dependent light-adaptive phenomena is discussed from a comparative perspective.

Research paper thumbnail of Ascending projections from the optic tectum in the lizard Podarcis hispanica

Visual Neuroscience, 1998

The ascending projections of the optic tectum, including their cells of origin, have been studied... more The ascending projections of the optic tectum, including their cells of origin, have been studied in the lizard Podarcis hispanica by means of a two-step experimental procedure. First, tracers were injected in the tectum to study the anterograde labeling in the forebrain. Second, the cells of origin of these projections have been identified by analyzing the retrograde labeling after tracer injections in the thalamus, hypothalamus, and pretectum. Three main tectal ascending pathways have been described: the dorsal tecto-thalamic tract (dtt), the medial tecto-thalamic tract (mtt), and the ventral tecto-thalamic tract (vtt). The dtt originates in radial cells of layers 5 and 7 and bipolar cells of layers 8 and 10 that project to the lateral neuropile of the dorsal lateral geniculate nucleus (GLD), to the intergeniculate leaflet (IGL), and to the ventral lateral geniculate nucleus (GLV). The mtt arises from radial neurons of layers 3 and 5 and bilaterally reaches the putative reticular thalamus and its boundary with the hypothalamus, the rostral IGL, and the area triangularis (AT). The vtt is composed of fibers from ganglion and multipolar cells of the layer 7 that project bilaterally to the nucleus of the vtt, the ventrolateral thalamic nucleus, the medial posterior thalamic nucleus (MP), the nucleus rotundus (Rot), the IGL, and the cell plate of the GLD. Therefore, the GLD receives not only direct retinal afferents but also two different tectal inputs, thus constituting a convergence point in the two visual pathways to the telencephalon. Moreover, different tectal cells specifically project to the ventrolateral thalamus and to pretectal nuclei. These results are discussed from comparative and functional viewpoints.

Research paper thumbnail of The septal complex of the telencephalon of the lizardPodarcis hispanica. I. chemoarchitectonical organization

The Journal of Comparative Neurology, 1995

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The Journal of Comparative Neurology, 1998

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combi... more The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.

Research paper thumbnail of Afferents to the red nucleus in the lizardPodarcis hispanica: Putative pathways for visuomotor integration

The Journal of Comparative Neurology, 1999

The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigat... more The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigated in the lizard Podarcis hispanica by using both retrograde and anterograde transport of tracers. Because the red nucleus constitutes a key structure in the limb premotor system, these sensory afferents probably are involved in visuomotor and other forms of sensorimotor integration. After tracer injections aimed at the red nucleus, retrograde labeling was found in the reticular thalamus, the subthalamus, the nucleus of the posterior commissure, as well as in two retinorecipient nuclei, namely, the ventral lateral and pretectal geniculate nuclei, where labeled cells are especially abundant. These geniculorubral projections have been confirmed by means of anterograde tracing with dextranamine injections. On the other hand, small injections of tracers in the retina demonstrated that its projections to the ventral lateral and pretectal geniculate nuclei are organized in a point-to-point fashion. Moreover, small tracer injections into the optic tectum of Podarcis indicated that the ventral lateral geniculate nucleus also receives a precisely organized tectal afferent. Taken together, these results strongly suggest that geniculorubral projections might constitute the neuroanatomical substrate for the generation of quick locomotor responses to appropriate visual stimuli. Additional ventral thalamic, subthalamic, and pretectal afferents to the red nucleus are likely to subserve other kinds of sensorimotor integration. These results help to clarify the organization of the reptilian motor system, including the telencephalic control of motor responses, and to unravel some of the major trends in the evolution of the limb premotor network of tetrapodian vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The Journal of Comparative Neurology, 1998

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combi... more The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.

Research paper thumbnail of Septal complex of the telencephalon of the lizard Podarcis hispanica. II. afferent connections

The Journal of Comparative Neurology, 1997

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Afferents to the red nucleus in the lizard Podarcis hispanica: Putative pathways for visuomotor integration

The Journal of Comparative Neurology, 1999

The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigat... more The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigated in the lizard Podarcis hispanica by using both retrograde and anterograde transport of tracers. Because the red nucleus constitutes a key structure in the limb premotor system, these sensory afferents probably are involved in visuomotor and other forms of sensorimotor integration. After tracer injections aimed at the red nucleus, retrograde labeling was found in the reticular thalamus, the subthalamus, the nucleus of the posterior commissure, as well as in two retinorecipient nuclei, namely, the ventral lateral and pretectal geniculate nuclei, where labeled cells are especially abundant. These geniculorubral projections have been confirmed by means of anterograde tracing with dextranamine injections. On the other hand, small injections of tracers in the retina demonstrated that its projections to the ventral lateral and pretectal geniculate nuclei are organized in a point-to-point fashion. Moreover, small tracer injections into the optic tectum of Podarcis indicated that the ventral lateral geniculate nucleus also receives a precisely organized tectal afferent. Taken together, these results strongly suggest that geniculorubral projections might constitute the neuroanatomical substrate for the generation of quick locomotor responses to appropriate visual stimuli. Additional ventral thalamic, subthalamic, and pretectal afferents to the red nucleus are likely to subserve other kinds of sensorimotor integration. These results help to clarify the organization of the reptilian motor system, including the telencephalic control of motor responses, and to unravel some of the major trends in the evolution of the limb premotor network of tetrapodian vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of the lizardPodarcis hispanica. II. afferent connections

The Journal of Comparative Neurology, 1997

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Seasonal sexually dimorphic distribution of neuropeptide Y-like immunoreactive neurons in the forebrain of the lizard Podarcis hispanica

Journal of Chemical Neuroanatomy, 1994

Since neuropeptide Y (NPY) is involved in several sex-specific physiological and behavioral proce... more Since neuropeptide Y (NPY) is involved in several sex-specific physiological and behavioral processes, a sexual dimorphic distribution is expected in forebrain areas that take part in the control of reproduction physiology and sexual behavior. This question has been studied in the lizard Podarcis hispanica by comparing the distribution of NPY-like immunoreactive cells in several forebrain areas of males and females during the season of active (spring/summer) and inactive (fall/winter) reproductive activity. Both qualitative observations and statistical analysis (analysis of variance) indicate that the number of reactive cells within two forebrain areas, the lateral septum and the periventricular preoptic nucleus, depends on the sex (P = 0.02) and season (P = 0.03) and that, in fact, intersexual differences depend on the season of the reproductive annual cycle (P = 0.046). Other areas, such as the amygdaloid nucleus sphericus, show neither sexual dimorphism (P = 0.67), nor seasonal variation in the number of reactive cells (P = 0.18), nor seasonal variation of the intersexual differences (P = 0.75). When analyzed independently, the lateral septum shows a clear sexual dimorphism in favour of females (P = 0.003) whereas the number of reactive cells in the periventricular preoptic nucleus is significantly higher (P = 0.006) in males than in females. In the case of the preoptic nucleus, this sexual dimorphism is clearly accentuated during the season of reproductive activity (P = 0.007), but this dependence is not so clear for the lateral septum (P = 0.059).(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Amical investigation of the afferents to the posterior dorsal ventricular ridge of the lizard Podarcis hispanica

European Journal of Neuroscience, 1998

ABSTRACT

Research paper thumbnail of A Lacertilian Dorsal Retinorecipient Thalamus: A Re-Investigation in the Old-World Lizard <i>Podarcis hispanica</i> (Part 2 of 2)

Brain, Behavior and Evolution, 1997

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of li... more The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells, is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.

Research paper thumbnail of A Lacertilian Dorsal Retinorecipient Thalamus: A Re-Investigation in the Old-World Lizard <i>Podarcis hispanica</i>

Brain, Behavior and Evolution, 1997

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of li... more The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells, is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.

Research paper thumbnail of Catecholaminergic interplexiform cells in the retina of lizards

Vision Research, 1996

An immunohistochemical study of the distribution of tyrosine hydroxylase has been performed in th... more An immunohistochemical study of the distribution of tyrosine hydroxylase has been performed in the retina of lizards of the genera Podarcis, Anolis and Tarentola. Immunoreactive cells extending their processes into the inner plexiform layer were observed in all three species. Reactive fibres in the outer plexiform layer were also seen in Podarcis and Anolis, and hence they possess not only amacrine but also catecholaminergic interplexiform cells. The retina of Anolis also showed reactive fibres aposed to the photoreceptors near the central fovea. The role of this outer retinal innervation on dopamine.dependent light-adaptive phenomena is discussed from a comparative perspective.

Research paper thumbnail of Ascending projections from the optic tectum in the lizard Podarcis hispanica

Visual Neuroscience, 1998

The ascending projections of the optic tectum, including their cells of origin, have been studied... more The ascending projections of the optic tectum, including their cells of origin, have been studied in the lizard Podarcis hispanica by means of a two-step experimental procedure. First, tracers were injected in the tectum to study the anterograde labeling in the forebrain. Second, the cells of origin of these projections have been identified by analyzing the retrograde labeling after tracer injections in the thalamus, hypothalamus, and pretectum. Three main tectal ascending pathways have been described: the dorsal tecto-thalamic tract (dtt), the medial tecto-thalamic tract (mtt), and the ventral tecto-thalamic tract (vtt). The dtt originates in radial cells of layers 5 and 7 and bipolar cells of layers 8 and 10 that project to the lateral neuropile of the dorsal lateral geniculate nucleus (GLD), to the intergeniculate leaflet (IGL), and to the ventral lateral geniculate nucleus (GLV). The mtt arises from radial neurons of layers 3 and 5 and bilaterally reaches the putative reticular thalamus and its boundary with the hypothalamus, the rostral IGL, and the area triangularis (AT). The vtt is composed of fibers from ganglion and multipolar cells of the layer 7 that project bilaterally to the nucleus of the vtt, the ventrolateral thalamic nucleus, the medial posterior thalamic nucleus (MP), the nucleus rotundus (Rot), the IGL, and the cell plate of the GLD. Therefore, the GLD receives not only direct retinal afferents but also two different tectal inputs, thus constituting a convergence point in the two visual pathways to the telencephalon. Moreover, different tectal cells specifically project to the ventrolateral thalamus and to pretectal nuclei. These results are discussed from comparative and functional viewpoints.

Research paper thumbnail of The septal complex of the telencephalon of the lizardPodarcis hispanica. I. chemoarchitectonical organization

The Journal of Comparative Neurology, 1995

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The Journal of Comparative Neurology, 1998

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combi... more The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.

Research paper thumbnail of Afferents to the red nucleus in the lizardPodarcis hispanica: Putative pathways for visuomotor integration

The Journal of Comparative Neurology, 1999

The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigat... more The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigated in the lizard Podarcis hispanica by using both retrograde and anterograde transport of tracers. Because the red nucleus constitutes a key structure in the limb premotor system, these sensory afferents probably are involved in visuomotor and other forms of sensorimotor integration. After tracer injections aimed at the red nucleus, retrograde labeling was found in the reticular thalamus, the subthalamus, the nucleus of the posterior commissure, as well as in two retinorecipient nuclei, namely, the ventral lateral and pretectal geniculate nuclei, where labeled cells are especially abundant. These geniculorubral projections have been confirmed by means of anterograde tracing with dextranamine injections. On the other hand, small injections of tracers in the retina demonstrated that its projections to the ventral lateral and pretectal geniculate nuclei are organized in a point-to-point fashion. Moreover, small tracer injections into the optic tectum of Podarcis indicated that the ventral lateral geniculate nucleus also receives a precisely organized tectal afferent. Taken together, these results strongly suggest that geniculorubral projections might constitute the neuroanatomical substrate for the generation of quick locomotor responses to appropriate visual stimuli. Additional ventral thalamic, subthalamic, and pretectal afferents to the red nucleus are likely to subserve other kinds of sensorimotor integration. These results help to clarify the organization of the reptilian motor system, including the telencephalic control of motor responses, and to unravel some of the major trends in the evolution of the limb premotor network of tetrapodian vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of lizards: III. Efferent connections and general discussion

The Journal of Comparative Neurology, 1998

The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combi... more The projections of the septum of the lizard Podarcis hispanica (Lacertidae) were studied by combining retrograde and anterograde neuroanatomical tracing. The results confirm the classification of septal nuclei into three main divisions. The nuclei composing the central septal division (anterior, lateral, medial, dorsolateral, and ventrolateral nuclei) displayed differential projections to the basal telencephalon, preoptic and anterior hypothalamus, lateral hypothalamic area, dorsal hypothalamus, mammillary complex, dorsomedial anterior thalamus, ventral tegmental area, interpeduncular nucleus, raphe nucleus, torus semicircularis pars laminaris, reptilian A8 nucleus/substantia nigra and central gray. For instance, only the medial septal nucleus projected substantially to the thalamus whereas the anterior septum was the only nucleus projecting to the caudal midbrain including the central gray. The anterior and lateral septal nuclei also differ in the way in which their projection to the preoptic hypothalamus terminated. The midline septal division is composed of the dorsal septal nucleus, nucleus septalis impar and nucleus of the posterior pallial commissure. The latter two nuclei projected to the lateral habenula and, at least the nucleus of the posterior pallial commissure, to the mammillary complex. The dorsal septal nucleus projected to the preoptic and periventricular hypothalamus and the anterior thalamus, but its central part seemed to project to the caudal midbrain (up to the midbrain central gray). Finally, the ventromedial septal division (ventromedial septal nucleus) showed a massive projection to the anterior and the lateral tuberomammillary hypothalamus. Data on the connections of the septum of P. hispanica and Gecko gekko are discussed from a comparative point of view and used for better understanding of the functional anatomy of the tetrapodian septum.

Research paper thumbnail of Septal complex of the telencephalon of the lizard Podarcis hispanica. II. afferent connections

The Journal of Comparative Neurology, 1997

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Afferents to the red nucleus in the lizard Podarcis hispanica: Putative pathways for visuomotor integration

The Journal of Comparative Neurology, 1999

The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigat... more The afferents to the red nucleus from visual and nonvisual forebrain centers have been investigated in the lizard Podarcis hispanica by using both retrograde and anterograde transport of tracers. Because the red nucleus constitutes a key structure in the limb premotor system, these sensory afferents probably are involved in visuomotor and other forms of sensorimotor integration. After tracer injections aimed at the red nucleus, retrograde labeling was found in the reticular thalamus, the subthalamus, the nucleus of the posterior commissure, as well as in two retinorecipient nuclei, namely, the ventral lateral and pretectal geniculate nuclei, where labeled cells are especially abundant. These geniculorubral projections have been confirmed by means of anterograde tracing with dextranamine injections. On the other hand, small injections of tracers in the retina demonstrated that its projections to the ventral lateral and pretectal geniculate nuclei are organized in a point-to-point fashion. Moreover, small tracer injections into the optic tectum of Podarcis indicated that the ventral lateral geniculate nucleus also receives a precisely organized tectal afferent. Taken together, these results strongly suggest that geniculorubral projections might constitute the neuroanatomical substrate for the generation of quick locomotor responses to appropriate visual stimuli. Additional ventral thalamic, subthalamic, and pretectal afferents to the red nucleus are likely to subserve other kinds of sensorimotor integration. These results help to clarify the organization of the reptilian motor system, including the telencephalic control of motor responses, and to unravel some of the major trends in the evolution of the limb premotor network of tetrapodian vertebrates.

Research paper thumbnail of Septal complex of the telencephalon of the lizardPodarcis hispanica. II. afferent connections

The Journal of Comparative Neurology, 1997

In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertid... more In this paper we study the septal complex architecture in the lizard Podarcis hispanica (Lacertidae). Histochemical and immunohistochemical techniques were used to define the distribution of zinc (Timm stain), acetyl cholinesterase (AChase), gamma-aminobutyric acid (GABA), tyrosine hydroxylase (TH), dopamine (DA), serotonin (5-HT), and two neuropeptides: leu-enkephalin (L-ENK) and substance P (SP). These reactions delineate a coherent map of nine septal nuclei that are named with a topographical nomenclature: anterior, lateral, ventromedial, medial, dorsolateral, ventrolateral, and dorsal septal nuclei, nucleus septalis impar, and nucleus of the posterior pallial commissure. The anterior septal nucleus is characterized by intense reaction for zinc and the presence of fibers immunoreactive for GABA, 5-HT, and L-ENK, which form pericellular nests. The lateral septal nucelus shows intense reaction for zinc, a high density of GABA-immunoreactive cells, and L-ENK-immunoreactive fibers forming basketlike figures around unstained somata. The ventromedial septal nucleus shows intense AChase reactivity, a dense network of 5-HT-immunoreactive fibers, and virtually no labeling for the other histochemical stains. The medial septal nucleus is defined by heavy reactivity for zinc, dense DA/TH and L-ENK innervations, and the presence of L-ENK-immunoreactive cells. The dorsolateral septal nucleus shows intense AChase staining in the neuropile and a dense network of fibers immunoreactive for 5-HT and DA/TH, but it shows low staining for zinc. The ventrolateral septal nucleus shows L-ENK-immunoreactive cells and a dense L-ENK innervation, but low reactivity for zinc. The dorsal septal nucleus, intermingled with the fimbrial fibers, shows a dense population of GABA-immunoreactive cells and terminals, but it is unreactive for zinc. Two subdivisions can be established in this dorsal septal nucleus: the dorsal part, intensely reactive for AChase and innervated by 5-HT fibers, and the central part, which shows L-ENK-immunoreactive neurons and fibers without reactivity for either AChase or 5-HT. The nucleus septalis impar, traversed by the fibers of the anterior pallial commissure (mildly reactive for zinc), shows reaction for AChase but low (if present) reactivity for the remaining markers. The nucleus of the posterior pallial commissure shows a generally low reactivity for the histochemical reactions employed. The distribution of these markers is similar to that found in other squamate reptiles and allows for a direct comparison with the septal formation of mammals. Such a comparison reinforces the view that the limbic system has undergone a conservative evolution within vertebrates.

Research paper thumbnail of Seasonal sexually dimorphic distribution of neuropeptide Y-like immunoreactive neurons in the forebrain of the lizard Podarcis hispanica

Journal of Chemical Neuroanatomy, 1994

Since neuropeptide Y (NPY) is involved in several sex-specific physiological and behavioral proce... more Since neuropeptide Y (NPY) is involved in several sex-specific physiological and behavioral processes, a sexual dimorphic distribution is expected in forebrain areas that take part in the control of reproduction physiology and sexual behavior. This question has been studied in the lizard Podarcis hispanica by comparing the distribution of NPY-like immunoreactive cells in several forebrain areas of males and females during the season of active (spring/summer) and inactive (fall/winter) reproductive activity. Both qualitative observations and statistical analysis (analysis of variance) indicate that the number of reactive cells within two forebrain areas, the lateral septum and the periventricular preoptic nucleus, depends on the sex (P = 0.02) and season (P = 0.03) and that, in fact, intersexual differences depend on the season of the reproductive annual cycle (P = 0.046). Other areas, such as the amygdaloid nucleus sphericus, show neither sexual dimorphism (P = 0.67), nor seasonal variation in the number of reactive cells (P = 0.18), nor seasonal variation of the intersexual differences (P = 0.75). When analyzed independently, the lateral septum shows a clear sexual dimorphism in favour of females (P = 0.003) whereas the number of reactive cells in the periventricular preoptic nucleus is significantly higher (P = 0.006) in males than in females. In the case of the preoptic nucleus, this sexual dimorphism is clearly accentuated during the season of reproductive activity (P = 0.007), but this dependence is not so clear for the lateral septum (P = 0.059).(ABSTRACT TRUNCATED AT 250 WORDS)

Research paper thumbnail of Amical investigation of the afferents to the posterior dorsal ventricular ridge of the lizard Podarcis hispanica

European Journal of Neuroscience, 1998

ABSTRACT

Research paper thumbnail of A Lacertilian Dorsal Retinorecipient Thalamus: A Re-Investigation in the Old-World Lizard <i>Podarcis hispanica</i> (Part 2 of 2)

Brain, Behavior and Evolution, 1997

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of li... more The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells, is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.

Research paper thumbnail of A Lacertilian Dorsal Retinorecipient Thalamus: A Re-Investigation in the Old-World Lizard <i>Podarcis hispanica</i>

Brain, Behavior and Evolution, 1997

The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of li... more The aim of this work is to delineate the retinorecipient cell groups of the dorsal thalamus of lizards and to study some of the differential connections in order to help to understand the evolution of the visual system in tetrapods. Tract-tracing and immunohistochemical techniques were applied to the retinorecipient dorsal thalamus of the lizard Podarcis hispanica. The retina of Podarcis projects to four areas of the dorsal thalamus: nucleus ovalis (Ov), intergeniculate leaflet (IGL), dorsal lateral geniculate nucleus (GLD) and dorsolateral anterior nucleus (DLA). Nucleus ovalis shows a clear cell plate/neuropile organization and projects to the ventral thalamus. Thus, it seems to belong to the ventral rather than to the dorsal thalamus. The IGL contains large cells reactive for GABA and/or NPY immunohistochemistry. It is interconnected with the supra/retrochiasmatic hypothalamus and projects to the opposite thalamus and to the ipsilateral tectum. The caudal DLA, which lacks both GABA- and NPY-like immunoreactive cells, is reached by a few thin retinal fibers, although distal dendrites of DLA cells enter the GLD, suggesting an important retinal input. The DLA projects to the medial and dorsal telencephalic cortices. The GLD is the main retinorecipient thalamic structure that projects to the telencephalon. It shows a crude laminar organization in which cell plate neurons project to the ipsilateral pallial thickening, but it does not receive a descending projection from the visual telencephalon and thus differs from the GLD of other amniotic vertebrates. In the context of present knowledge, these results suggest that an IGL homologue is present in all tetrapods studied, whereas Ov seems to be restricted to diapsid vertebrates. Moreover, our data suggest that a unimodal visual projection to the telencephalon (arising from the GLD) first appeared in reptiles by segregation from a limbic (multimodal) thalamo-telencephalic pathway.