Somatotopic maps within the zona incerta relay parallel GABAergic somatosensory pathways to the neocortex, superior colliculus, and brainstem

Nicolelis, Miguel A. L.; Chapin, John K.; Lin, Rick C.S.

doi:10.1016/0006-8993(92)90546-l

Cited by 125 publications

(169 citation statements)

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“…We chose to focus on the role of GABAergic inputs from the ZI for the following reasons. Unlike the other nuclei, ZI neurons respond at short latency (4 msec) to whisker stimuli (Nicolelis et al, 1992; our unpublished observations), suggesting that they may mediate feed-forward inhibition of POm neurons. Furthermore, unlike TRN axons, which terminate on distal dendrites of thalamocor\tical projection neurons (Peschanski et al, 1983;Wang et al, 2001), ZI axons synapse on the perisomatic regions of these cells (Bartho et al, 2002), suggesting that they exert potent tonic inhibition of POm neurons.…”

Section: Zi Regulates Pom Responsesmentioning

confidence: 72%

“…2) (see Materials and Methods). The lesions were 300 -500 m in diameter and included the dorsal/ventral subregions of the ZI, which contain somatotopic representations of the whiskers (Nicolelis et al, 1992). We compared data obtained from neurons recorded from the control group (rats with intact ZI) with data from neurons recorded from the ZI inactivated group (rats receiving ZI lesions before POm recordings).…”

Section: Zi Regulates Pom Responsesmentioning

confidence: 99%

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Reducing the Uncertainty: Gating of Peripheral Inputs by Zona Incerta

Trageser

Keller²

2004

J. Neurosci.

155

152

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Sensory inputs are relayed to the neocortex by "first-order" thalamic nuclei, the responses of which are determined by ascending inputs from peripheral receptors. In contrast, "higher-order" thalamic nuclei respond poorly to peripheral inputs, and their responses are thought to be determined by descending cortical inputs. We tested this hypothesis by recording from neurons in the higher-order somatosensory posterior medial (POm) nucleus of narcotized rats. As reported previously, POm neurons responded to whisker stimuli with long-latency (median, 27 msec) and low-magnitude responses, consistent with cortically driven responses. However, when we suppressed inhibitory inputs from the subthalamic nucleus zona incerta (ZI), POm responses were of significantly higher magnitude and shorter latency, with many POm neurons responding at latencies consistent with ascending driving inputs from trigeminal nuclei. Our data suggest that POm comprises two neuronal populations: one population is driven by both peripheral and cortical inputs, and the second population responds only to cortical inputs. These findings demonstrate that ZI gates peripheral inputs to POm, enabling it to function both as a first-order and higher-order nucleus. Because ZI innervates all higher-order nuclei, this gating mechanism may exert similar regulation of thalamic processing in other sensory systems.

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Section: Zi Regulates Pom Responsesmentioning

confidence: 72%

Section: Zi Regulates Pom Responsesmentioning

confidence: 99%

Reducing the Uncertainty: Gating of Peripheral Inputs by Zona Incerta

Trageser

Keller²

2004

J. Neurosci.

155

152

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“…The predominant transmitter used by the cells in both these sublaminae is GABA. For example, both the incertotectal projection from vZI [rat: Kim et al (1992) and Nicolelis et al (1992); cat: Ficalora and Mize (1989)] and the incertocortical projection from dZI [rat: Lin et al (1990) and Nicolelis et al (1992)] are GABAergic. This makes the incertotectal pathway a long-range inhibitory influence over the superior colliculus (SC), which parallels the GABAergic nigrotectal projection from pars reticulata [rat: Redgrave et al (1992); cat: Graybiel (1978), Harting et al (1988), and Ficarola and Mize (1989); squirrel: May and Hall (1984)].…”

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confidence: 99%

“…Several of the projections described as ending primarily in vZI are somatosensory in nature. Inputs from somatosensory cortex, the trigeminal nuclei, and the dorsal column nuclei terminate in this sublamina in the rat (Nicolelis et al, 1992;Mitrofanis and Mikuletic, 1999;Wang et al, 2004). These same somatosensory structures also provide inputs directly to the SC, where they help determine the pattern of saccade-related activity [monkey: Groh and Sparks (1996); rat: Redgrave et al (1996)].…”

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confidence: 99%

“…Thus, the ascending somatosensory inputs to the SC from the trigeminal nuclei and spinal cord, as well as the descending ones from somatosensory cortex, may converge with an inhibitory somatosensory feed-forward path that includes ZI [rat: Killackey and Erzurumlu (1981), Huerta et al (1983), Cadusseau and Roger (1985), and Rhoades et al (1989); cat: Huerta et al (1981) and Meredith and Clemo (1989); macaque: Wiberg et al (1987)]. However, at present, most of the evidence concerning somatosensory inputs to ZI comes from experiments conducted in the rodent model, where the somatosensory system provides the dominant modality for controlling behavior (Nicolelis et al, 1992;Redgrave et al, 1996;Shaw and Mitrofanis, 2002). It remains to be determined whether somatosensory inputs to ZI are as prominent in species where the visual system dominates.…”

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Projections of somatosensory cortex and frontal eye fields onto incertotectal neurons in the cat

et al. 2006

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The goal of this study was to determine whether the input-output characteristics of the zona incerta (ZI) are appropriate for it to serve as a conduit for cortical control over saccade-related activity in the superior colliculus. The study utilized the neuronal tracers wheat germ agglutininhorseradish peroxidase (WGA-HRP) and biotinylated dextran amine (BDA) in the cat. Injections of WGA-HRP into primary somatosensory cortex (SI) revealed sparse, widespread nontopographic projections throughout ZI. In addition, region-specific areas of more intense termination were present in ventral ZI, although strict topography was not observed. In comparison, the frontal eye fields (FEF) also projected sparsely throughout ZI, but terminated more heavily, medially, along the border between the two sublaminae. Furthermore, retrogradely labeled incertocortical neurons were observed in both experiments. The relationship of these two cortical projections to incertotectal cells was also directly examined by retrogradely labeling incertotectal cells with WGA-HRP in animals that had also received cortical BDA injections. Labeled axonal arbors from both SI and FEF had thin, sparsely branched axons with numerous en passant boutons. They formed numerous close associations with the somata and dendrites of WGA-HRP-labeled incertotectal cells. In summary, these results indicate that both sensory and motor cortical inputs to ZI display similar morphologies and distributions. In addition, both display close associations with incertotectal cells, suggesting direct synaptic contact. From these data, we conclude that inputs from somatosensory and FEF cortex both play a role in controlling gaze-related activity in the superior colliculus by way of the inhibitory incertotectal projection. Anat Rec Part A, 288A: 1310-1329, 2006.2006 Wiley-Liss, Inc.

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Entorhinal cortex modules of the human brain

Solodkin

Hoesen

1996

J. Comp. Neurol.

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Much is known about modular organization in the cerebral cortex, but this knowledge is skewed markedly toward primary sensory areas, and in fact, it has been difficult to demonstrate elsewhere. In this report, we test the hypothesis that a unique form of modules exists in the entorhinal area of the human cortex (Brodmann's area 28). We examined this issue using classic cyto- and myeloarchitectonic stains, immunolabeling for various neurochemicals, and histochemistry for certain enzymes. The findings reveal that the entorhinal cortex in the human is formed by a mosaic of cellular aggregates whose most conspicuous elements are the cell islands of layer II and myelinated fibers around the cell islands, the disposition of glutamic acid decarboxylase-positive neurons and processes, cytochrome oxidase staining, and the pattern of cholinergic afferent fibers. The neuropathology of Alzheimer's disease cases highlights the modules, but inversely so, by destroying their features. The findings are of interest because 1) anatomically defined modules are shown to be present in areas other than the sensory and motor cortices, 2) the modules are morphological entities likely to reflect functions of the entorhinal cortex, and 3) the destruction of entorhinal cortex modules may account disproportionately for the severity of memory impairments in Alzheimer's disease.

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Somatotopic maps within the zona incerta relay parallel GABAergic somatosensory pathways to the neocortex, superior colliculus, and brainstem

Cited by 125 publications

References 39 publications

Reducing the Uncertainty: Gating of Peripheral Inputs by Zona Incerta

Reducing the Uncertainty: Gating of Peripheral Inputs by Zona Incerta

Projections of somatosensory cortex and frontal eye fields onto incertotectal neurons in the cat

Entorhinal cortex modules of the human brain

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