Organization of the Cerebral Cortex in Turtle

Desan, Paul H.

doi:10.1159/000415848

Cited by 43 publications

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“…The oscillations have been studied mostly in the anesthetized cat but more recently also in awake, behaving monkeys (9,10). The present finding of visually induced synchronizing oscillations in a band (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) Hz) that might be equivalent, adjusting for body temperature, in a reptilian cortex suggests that synchrony may be a fundamental feature of visual processing in amniotes.…”

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confidence: 66%

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Visual motion induces synchronous oscillations in turtle visual cortex.

Prechtl

1994

Proc. Natl. Acad. Sci. U.S.A.

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In mammalian brains, multielectrode recordings during sensory stimulation have revealed oscillations in different cortical areas that are transiently synchronous. These synchronizations have been hypothesized to support integration of sensory information or represent the operation of attentional mechanisms, but their stimulus requirements and prevalence are still unclear. Here I report an analogous synchronization in a reptilian cortex induced by moving visual stimuli. The synchronization, as measured by the coherence function, applies to spindle-like 20-Hz oscillations recorded with multiple electrodes implanted in the dorsal cortex and the dorsal ventricular ridge of the pond turtle. Additionally, widespread increases in coherence are observed in the 1-to 2-Hz band, and widespread decreases in coherence are seen in the 10-and 30-to 45-Hz bands. The 20-Hz oscillations induced by the moving bar or more natural stimuli are nonstationary and can be sustained for seconds. Early reptile studies may have interpreted similar spindles as electroencephalogram correlates of arousal; however, the absence of these spindles during arousing stimuli in the dark suggests a more specific role in visual processing. Thus, visually induced synchronous oscillations are not unique to the mammalian cortex but also occur in the visual area of the primitive three-layered cortex of reptiles.

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confidence: 66%

“…Whereas the DC pathway is similar to the geniculocortical system of mammals, the DVR system is hypothesized to be analogous to the colliculo-thalamo-extrastriate cortical pathway (18). The DC and DVR are reciprocally connected (19,20) and 12470 Neurobiology: Prechtl Proc. Natl.…”

Section: Discussionmentioning

confidence: 99%

Visual motion induces synchronous oscillations in turtle visual cortex.

Prechtl

1994

Proc. Natl. Acad. Sci. U.S.A.

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“…In this study we compare the results just as they have been described by the authors. Considering the fact that retrograde studies with HRP in Podarcis hispanica [MartinezGarcia and Lorente, 1990], Gekko gecko, Iguana iguana [Bruce and Butler, 1984], Tupinambis nigropunctatus [Lohman and van Woerden-Verkley, 1978] and turtles [Desan, 1988] showed that in all these reptiles Dla is the only dorsal thalamic nucleus that projects to the medial cortex, we assumed that also in Eublepharius macularius thalamic efferents to the medial cortex originate in the Dla. Therefore, we did no retrograde experiments in this lizard.…”

Section: Discussionmentioning

confidence: 99%

“…The cortical afferents terminate on the middle and distal parts [for reviews, see Witter et al, 1989;Lohman and Smeets, 1991]. In the reptiles studied, a thalamic projection originating in the nucleus dorsolateralis thalami (Dla) terminates on the middle parts of the apical dendrites [Lohman and van Woerden-Verkley, 1978;Desan, 1988;. A comparable thalamic projection is absent in mammals.…”

Section: Introductionmentioning

confidence: 99%

Convergence of Thalamic and Cholinergic Projections in the ‘Dentate Area’ of Lizards

et al. 1998

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The small-celled part of the medial cortex (Cxms) in lizards is comparable to the hippocampal area dentata in mammals. As in mammals, most of the afferents to this cortical area are arranged in sharply delimited laminae. In reptiles this lamination pattern is species-specific. In the lizard Tupinambis nigropunctatus projections from the multisensory dorsolateral thalamic nucleus (Dla) terminate in the middle one-third of the outer plexiform layer throughout the whole rostrocaudal extent of Cxms. In Podarcis hispanica the thalamic projections terminate not only in the middle one-third of Cxms but also in the inner plexiform layer. To find out whether the species-related variation of thalamic projections to Cxms is a solitary phenomenon or is related to variations of other afferents of Cxms, we studied the relationships between the thalamic and cholinergic projections from the basal telencephalon in the medial cortex of three lizard families: the Lacertidae, the Teiidae and the Gekkonidae. In the gekkonid lizards Gekko gecko and Eublepharius macularius, Dla projections were studied with the anterograde tracer Phaseolus vulgaris-leucoagglutinin. Projections were found in only the rostral one-third of Cxms where the fibers terminate in the superficial half of the outer plexiform layer and in the deep half of the inner plexiform layer. From acetylcholinesterase staining in the Cxms of representatives of these three lizard families, it appeared that the main cholinergic afferents terminate in the same subregions and the same laminae as the Dla projections. Therefore, there seems to be a close association between thalamic and cholinergic afferents in the Cxms of lizards, irrespective of their precise location in the cortex of the various species. This suggests a functional relationship between these two afferents of the dentate area in lizards.

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“…Thus, the rotundal target within the DVR is visual, and electrophysiological and lesion studies have confirmed that it plays a prominent role in the visual behavior of reptiles and birds Powers, 1980, 1983;Dunser et al, 1981;Bass et al, 1983]. Because the visual area within DVR is clearly distinct from the primary visual area in the Wulst of birds and in the dorsal cortex of turtles [Hall and Ebner, 1970a;Hall et al, 1977;Desan, 1988;Ulinski, 1988], and because this secondary telencephalic visual area receives visual input from a thalamic region that receives its visual input from the tectum, we will refer to the rotundorecipient visual area of the DVR as the tectothalamofugal visual area, or Vtt. The primary visual area in dorsal cortex and in the Wulst, which appears homologous to primary visual area 17 of mammalian neocortex, will be referred to as V1 [Karten, 1969[Karten, , 1991Nauta and Karten, 1970;Medina and Reiner, 1999].…”

Section: Introductionmentioning

confidence: 99%

Succinic Dehydrogenase Histochemistry Reveals the Location of the Putative Primary Visual and Auditory Areas within the Dorsal Ventricular Ridge of <i>Sphenodon punctatus</i>

Reiner¹,

Northcutt²

2000

Brain Behav Evol

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In turtles, crocodilians, lizards and snakes, the dorsal ventricular ridge (DVR) is a nuclear cell mass that contains distinct visual and auditory thalamorecipient cell groups. In the tuatara (Sphenodon punctatus), the DVR is not organized into diverse cell groups but instead possesses a trilaminar cytoarchitecture resembling that characteristic of the telencephalic cortex in reptiles. To determine if visual and auditory fields might also be present in the DVR of Sphenodon punctatus, we used succinic dehydrogenase (SDH) histochemistry, which has been shown to delineate the visual and auditory fields of the DVR in turtles, crocodilians and lizards. We also used acetylcholinesterase (AChE) histochemistry to determine the boundary between the DVR and the basal ganglia in Sphenodon. We found an SDH-rich region in the neuropil ventral to the cell plate of the rostrolateral DVR and a slightly less intense SDH-rich zone in the neuropil deep to the cell plate of the ventromedial DVR. These SDH-rich zones appear to be located at the apical dendrites of the neurons of the adjacent cell plate. These SDH-rich zones were clearly located within the DVR and were distinct from the AChE-rich striatal part of the basal ganglia, which occupied the ventrolateral wall of the telencephalon. Based on findings in other reptiles, it seems likely that the SDH-rich zone in rostrolateral DVR represents the zone of termination of nucleus rotundus visual input to the DVR, whereas the zone in ventromedial DVR represents the zone of termination of nucleus reuniens auditory input. Because a trilaminar DVR such as that in Sphenodon might be the primitive DVR condition for reptiles, our results suggest that the cytoarchitecture of the DVR and the synaptic organization of its thalamic sensory input in the common ancestor of living reptiles might have been much like of the dorsal cortex.

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Organization of the Cerebral Cortex in Turtle

Cited by 43 publications

References 0 publications

Visual motion induces synchronous oscillations in turtle visual cortex.

Visual motion induces synchronous oscillations in turtle visual cortex.

Convergence of Thalamic and Cholinergic Projections in the ‘Dentate Area’ of Lizards

Succinic Dehydrogenase Histochemistry Reveals the Location of the Putative Primary Visual and Auditory Areas within the Dorsal Ventricular Ridge of <i>Sphenodon punctatus</i>

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