Rhinal sulcus

About: Rhinal sulcus is a research topic. Over the lifetime, 116 publications have been published within this topic receiving 14784 citations.

Frontal lobe and kindling in the rat.

Abstract: To test the hypothesis that the cortex participates in amygdaloid kindling in rats, bilateral aspiration lesions were made in various cortical areas in rats prior to kindling. Lesions in orbital cortex (on the dorsal lip of the rhinal sulcus) or prefrontal cortex (area 10) significantly retarded the rate of amygdaloid kindling; lesions in motor cortex, anterior cingulate cortex, or visual cortex were without effect. Detailed analysis indicated that the orbital lesioned and frontal-lesioned rats kindled relatively normally up to the second-last stage of amygdaloid kindling, in which stage they perseverated significantly longer than the controls and the other lesioned rats. These results suggest that areas of the frontal lobe participate in the elaboration and generalization of amygdaloid seizures in rats. Although retarded in rate, kindling nonetheless occurred in the lesioned rats, indicating that these cortical areas are not essential for the development of amygdaloid seizures.

Propagation of neuronal activity along the neocortical-perirhinal-entorhinal pathway in the guinea pig.

Abstract: The study of synaptic interactions within the parahippocampal region is crucial to understand the integrative functions performed by this region during memory information processing. Despite the extensive anatomical studies, the intrinsic physiology of the parahippocampal area has been poorly investigated. We describe here the organization pattern of the synaptic network formed by the temporal neocortex, areas 36 and 35 of the perirhinal cortex (PRC) and the entorhinal cortex (EC), in the in vitro isolated guinea-pig brain. Current source density analysis of laminar field potential profiles was performed with multichannel silicon probes positioned in different parahippocampal subfields. Stimulation of the temporal neocortex induced monosynaptic and polysynaptic potentials in areas 35 and 36, respectively. Area 36 stimulation evoked monosynaptic responses within areas 36 and 35. Stimuli in area 35 induced responses that propagated longitudinally along area 35 itself. No local field responses were observed in the EC after stimulation of both neocortex and areas 35/36. Despite the absence of a local extracellular response, intracellular recordings demonstrated that subpopulations of superficial layer neurons in medial and lateral EC showed polysynaptic EPSPs after stimulation of area 35 and area 36. The results demonstrate that the propagation of neuronal activity across the rhinal sulcus in the direction from the PRC to the EC is finely and diffusely distributed. In agreement with previous reports, these findings suggest that the PRC-EC pathway is highly regulated by inhibitory network interactions.

The organization of the sensory and motor areas of cerebral cortex in the platypus (Ornithorhynchus anatinus)

Abstract: The organization of sensory and motor regions of the cerebral cortex has been studied in the platypus (Ornithorhynchus anatinus), of the order Monotremata. Comparisons were made with the organization found in the other representative of this order, the echidna, and with primitive species of eutherian and metatherian mammals. Evoked potential and single neuron studies revealed a large single area of somatosensory representation in the posterior region of the hemisphere, extending from an approximately mid-sagittal position around to the region of the rhinal sulcus on the ventrolateral surface of the hemisphere. The mediolateral representation of contralateral body parts was consistent with the pattern in the primary somatosensory area of other mammalian species. No evidence of a second somatosensory area was found. Neurons with similar receptive fields were grouped in columns normal to the cortical surface and a highly ordered pattern of somatotopic representation was found. Within the large area of bill representation individual neurons had receptive fields which were often punctate and no more than 1 mm in diameter. They responded to dynamic components of tactile stimuli delivered to their receptive fields on the bill. Movements on the contralateral side of the body could be elicited by bipolar electrical stimulation over an area on the dorsal surface of the hemisphere which largely overlapped the somatosensory area, but extended further anteriorly towards the frontal pole of the hemisphere. Visual and auditory projection regions were found overlapping the somatosensory area in the posterior part of the hemisphere. The auditory area overlapped the visual area and appeared to be displaced posteromedially in relation to its position in other species, a displacement which may be a consequence of the large expanse of cortical area associated with the bill. The observation that a large proportion of cortical area is devoted to specific sensory and motor function in platypus corresponds with earlier findings in primitive eutherian and metatherian species. The platypus neocortex appears to represent a more primitive stage of cortical development than that found in the other member of the order Monotremata, the echidna.

Cortical and brain stem afferents to the ventral thalamic nuclei of the cat demonstrated by retrograde axonal transport of horseradish peroxidase.

Abstract: After horseradish peroxidase (HRP) injections into various parts of the ventral thalamic nuclear group and its adjacent areas, the distribution of labeled neurons was compared in the cerebral cortex, basal ganglia, and the brain stem. The major differences in distribution patterns were as follows: Injections of HRP into the lateral or ventrolateral portions of the ventroanterior and ventrolateral nuclear complex of the thalamus (VA-VL) produced retrogradely labeled neurons consistently in area 4 gamma (lateral part of the anterior and posterior sigmoid gyri, lateral sigmoid gyrus and the lateral fundus of the cruciate sulcus), the medial division of posterior thalamic group (POm), suprageniculate nucleus (SG) and anterior pretectal nucleus ipsilaterally, and in the nucleus Z of the vestibular nuclear complex bilaterally. Injections into the medial or dorsomedial portion of the VA-VL resulted in labeled neurons within the areas 6a beta (medial part of the anterior sigmoid gyrus), 6a delta (anterior part of ventral bank of buried cruciate sulcus), 6 if. fu (posterior part of the bank), fundus of the presylvian sulcus (area 6a beta), medial part of the nucleus lateralis posterior of thalamus and nucleus centralis dorsalis ipsilaterally, and in the entopeduncular nucleus (EPN) and medial pretectal nucleus bilaterally. Only a few neurons were present in the contralateral area 6a delta. After HRP injections into the ventral medial nucleus (VM), major labeled neurons were observed in the gyrus proreus, area 6a beta (mainly in the medial bank of the presylvian sulcus), and EPN ipsilaterally, and in the medial pretectal nucleus and substantia nigra bilaterally. Following HRP injections into the centre median nucleus (CM), major labeled neurons were found in the areas 4 gamma, 6a beta, and the orbital gyrus ipsilaterally, and in the EPN, rostral and rostrolateral parts of the thalamic reticular nucleus, locus ceruleus, nucleus reticularis pontis oralis et caudalis and nucleus prepositus hypoglossi bilaterally. The contralateral intercalatus nucleus also possessed labeled neurons. With HRP injections into the paracentral and centrolateral nuclei, labeled neurons were observed in the gyrus proreus and the cortical areas between the caudal presylvian sulcus and anterior rhinal sulcus ipsilaterally, and in the nuclei interstitialis and Darkschewitsch bilaterally. Minor differences in the distribution pattern were observed in the superior colliculus, periaqueductal gray, mesencephalic and medullary reticular formations, and vestibular nuclei in all cases of injections.