Formation of the Looming-evoked Innate Defensive Response during Postnatal Development in Mice / 神经科学通报·英文版

Environmental threats often trigger innate defensive responses in mammals. However, the gradual development of functional properties of these responses during the postnatal development stage remains unclear. Here, we report that looming stimulation in mice evoked flight behavior commencing at P14-16 and had fully developed by P20-24. The visual-evoked innate defensive response was not significantly altered by sensory deprivation at an early postnatal stage. Furthermore, the percentages of wide-field and horizontal cells in the superior colliculus were notably elevated at P20-24. Our findings define a developmental time window for the formation of the visual innate defense response during the early postnatal period and provide important insight into the underlying mechanism.

Short-Term Visual Experience Leads to Potentiation of Spontaneous Activity in Mouse Superior Colliculus / 神经科学通报·英文版

Spontaneous activity in the brain maintains an internal structured pattern that reflects the external environment, which is essential for processing information and developing perception and cognition. An essential prerequisite of spontaneous activity for perception is the ability to reverberate external information, such as by potentiation. Yet its role in the processing of potentiation in mouse superior colliculus (SC) neurons is less studied. Here, we used electrophysiological recording, optogenetics, and drug infusion methods to investigate the mechanism of potentiation in SC neurons. We found that visual experience potentiated SC neurons several minutes later in different developmental stages, and the similarity between spontaneous and visually-evoked activity increased with age. Before eye-opening, activation of retinal ganglion cells that expressed ChR2 also induced the potentiation of spontaneous activity in the mouse SC. Potentiation was dependent on stimulus number and showed feature selectivity for direction and orientation. Optogenetic activation of parvalbumin neurons in the SC attenuated the potentiation induced by visual experience. Furthermore, potentiation in SC neurons was blocked by inhibiting the glutamate transporter GLT1. These results indicated that the potentiation induced by a visual stimulus might play a key role in shaping the internal representation of the environment, and serves as a carrier for short-term memory consolidation.

The Amygdala Responds Rapidly to Flashes Linked to Direct Retinal Innervation: A Flash-evoked Potential Study Across Cortical and Subcortical Visual Pathways / 神经科学通报·英文版

Rapid detection and response to visual threats are critical for survival in animals. The amygdala (AMY) is hypothesized to be involved in this process, but how it interacts with the visual system to do this remains unclear. By recording flash-evoked potentials simultaneously from the superior colliculus (SC), lateral posterior nucleus of the thalamus, AMY, lateral geniculate nucleus (LGN) and visual cortex, which belong to the cortical and subcortical pathways for visual fear processing, we investigated the temporal relationship between these regions in visual processing in rats. A quick flash-evoked potential (FEP) component was identified in the AMY. This emerged as early as in the LGN and was approximately 25 ms prior to the earliest component recorded in the SC, which was assumed to be an important area in visual fear. This quick P1 component in the AMY was not affected by restraint stress or corticosterone injection, but was diminished by RU38486, a glucocorticoid receptor blocker. By injecting a monosynaptic retrograde AAV tracer into the AMY, we found that it received a direct projection from the retina. These results confirm the existence of a direct connection from the retina to the AMY, that the latency in the AMY to flashes is equivalent to that in the sensory thalamus, and that the response is modulated by glucocorticoids.

Ectopic Expression of Ephrin-A5 Under the EphA8 Promoter at the Anterior Region of the Superior Colliculus

EphA/ephrin-A mediated signaling has emerged as a key mechanism regulating axon guidance and topographic mapping, particularly in the well-characterized visual system from the retina to the superior colliculus (SC). In this study, EphA8 bacterial artificial chromosome (BAC) was manipulated to contain a floxed eGFP and human ephrin-A5 expression cassette using homologous recombination method. In the mice containing the recombinant BAC, it was shown that GFP is expressed in an anterior>posterior gradient in the SC. Furthermore, when these mice were crossed with the transgenic mice expressing Cre under the EphA8 promoter, it was evident that a GFP expression cassette was eliminated, and that human ephrin-A5 was ectopically expressed in the anterior region of the SC. This transgenic model would be useful to analyze the role of ephrin-A5 in the SC during the retinocollicular topography formation.

NMDA receptor blockade alters the intracellular distribution of neuronal nitric oxide synthase in the superficial layers of the rat superior colliculus

Nitric oxide (NO) is a molecular messenger involved in several events of synaptic plasticity in the central nervous system. Ca2+ influx through the N-methyl-D-aspartate receptor (NMDAR) triggers the synthesis of NO by activating the enzyme neuronal nitric oxide synthase (nNOS) in postsynaptic densities. Therefore, NMDAR and nNOS are part of the intricate scenario of postsynaptic densities. In the present study, we hypothesized that the intracellular distribution of nNOS in the neurons of superior colliculus (SC) superficial layers is an NMDAR activity-dependent process. We used osmotic minipumps to promote chronic blockade of the receptors with the pharmacological agent MK-801 in the SC of 7 adult rats. The effective blockade of NMDAR was assessed by changes in the protein level of the immediate early gene NGFI-A, which is a well-known NMDAR activity-dependent expressing transcription factor. Upon chronic infusion of MK-801, a decrease of 47 percent in the number of cells expressing NGFI-A was observed in the SC of treated animals. Additionally, the filled dendritic extent by the histochemical product of nicotinamide adenine di-nucleotide phosphate diaphorase was reduced by 45 percent when compared to the contralateral SC of the same animals and by 64 percent when compared to the SC of control animals. We conclude that the proper intracellular localization of nNOS in the retinorecipient layers of SC depends on NMDAR activation. These results are consistent with the view that the participation of NO in the physiological and plastic events of the central nervous system might be closely related to an NMDAR activity-dependent function.

Changes of Calretinin-Immunoreactivities in the Rat Superior Collicuclus after Eye Enucleation / 체질인류학회지

Calcium-binding proteins play an important role in the protection, differentiation, and reorganization of the central nervous system. The effects of neonatal retinal deafferentiation on calretinin, and tracing of retinotectal pathway were examined immunohistochemically in the superficial layer of the rat superior colliculus. Tracing with cholera toxin was revealed on the superior colliculus contralateral to the ocular injection. On the contralateral side of superior colliculus, the calretinin-immunoreactive (IR) cells were dramatically increased, calretinin-IR fibers were markedly decreased in the superficial layer. These results show that retinal deafferentation results in an increase of calretinin-immunoreactive cells within the superficial layers of the superior colliculus, which suggest reorganization of neurons in superior colliculus.

Changes of beta-Adrenergic Receptor mRNA in the Visual Cortex and Superior Colliculus of Monocular Deprivated Rat

PURPOSE: To investigate the change of the Beta adrenergic system in the rat visual cortex and superior colliculus after visual deprivation during a critical period of postnatal development. METHODS: The changes of beta 1 and beta 2 adrenergic receptor mRNA were investigated by using northern blot analysis in the rat visual cortex and superior colliculus. The right eyelid of visually deprived rat was sutured at the 10th postnatal days. After visual deprivation for 4 weeks, the rat were sacrificed and the visual cortex and superior colliculus tissues were removed for analysis. RESULTS: Beta 1 and beta 2 adrenergic receptor mRNA expression was decreased in the contralateral visual cortex to the deprived eye. In the superior colliculus, beta 2 adrenergic receptor mRNA expression increased in both sides, but a much greater increase was shown in the ipsilateral superior colliculus than the contralateral side. CONCLUSIONS: These results suggests that visual deprivation during a critical period of postnatal development influences the beta adrenergic system in the rat visual cortex and superior colliculus.

Distribution of Neuropeptides-Containing Neurons in the Superior Colliculus of the Cat Brain

The distribution and morphology of cholecystokinin-8 (CCK 8)-, neuropeptide Y (NPY)-, Substance P (SP)- and vasoactive intestinal polypeptide (VIP)-immunoreactivity were examined in the cat superior colliculus (SC) by means of immunohistochemistry. Judging from this study, some neuropeptides-IR neurons may be present in the superficial layers of the sc. And these neurons and neuropeptides may be involved in the functions of the superficial layers.

Distribution of Serotonin-2 Receptor in the Superior Collicullus of the Adult Rat: A Radioarutographic Study

The superior colliculus is a laminated structure that consisted with superficial and deep layers in the roof of midbrain and the center of visual information and sensorimotor intergration. The deep layers of the mammalian superior colliculus are concerned with generation of eye movements. Serotonin is a neurotransmitter of the central nervous system and its binding sites can be classified into serotonin-1 receptor, serotonin-2 receptor and serotonin-3 receptor according to their pharmacological characteristics. The serotonin-2 receptors in the human brain presents in the motor cortex(area 4 of Brodmann) which role for the control of ocular motor activity and in the primary and secondary visual areas(areas 17 and 18 of Brodmann). Some of them presents in the limbic system role for the control of emotive activity, memory and other limbic functions. We performed this experiment to identify the anatomical distribution of the serotonergic nerve terminals in the superior colliculus of the rat by microscopicautography. It has been demonstrated that the serotonin-2 receptors of the superior colliculus are concerned with generation of saccade eye movements.

CONNECTION BETWEEN THE SUPERIORCOLLICULUS AND LATERAL GENICULATE BODY IN THE GOLDEN HAMSTER / 解剖学报

Connection between the superior colliculus(SC)and the dorsal and ventral lateral geniculate nuclei (LGd and LGv) were studied in adult golden hamsters using anterograde and retrograde pathway tracing methods 1. In four hamsters, the cytoarchitecture of the SC, LGd and LGv was examined in brain sections stained with Nissl's or Loyez's method. 2. A single injection of a mixture of ~3H-leucine and ~3H-proline was made into various regions of the SC in each of 4 animals (1 day survival) for studying the pattern of terminal distribution of the projections from the SC to the ipsilateral LGd and LGv. In animals where the injection site was located in the superficial gray layers of the lateral portion of the SC, labelled terminals were found in the caudal lateral part of the LGd and LGv. In the case where the injection was restricted in more medial part of the SC, the terminal labelling was observed in the rostral lateral portion of the lateral geniculate nuclei. 3. One day after an injection of horseradish peroxidase (HRP) into the LGd (4 animals), LGv(2 animals), or LP(2 animals) labelled neurons were observed in the superficial gray layers of the ipsilateral superior colliculus. No HRP-labelled neuron was detected in deeper laminae in the colliculus. These results indicate that neurons in the superficial gray layers of the SC project to the ipsilateral LGd and LGv, and the projections are organized topogra- phically according to the retinotopic or visual field map

SOURCES OF THE SUPERIOR COLLICULUS AFFERENTS IN THE ALBINO RAT: AN HRP-LABELING STUDY / 解剖学报

HRP solution (33%) was injected into the left superior colliculus of 21 adult albino rats. 1-2 days after injection, the animal was sacrificed. Brains were frozen sectioned and processed according to. DAB- or TMB-method. The labeled neurones were examined in the right superior colliculus and other areas of the brain. The resu ts are as follows:1. No matter where the HRP was injected (either in the rostral or caudal part of the superior colliculus or thepart between them) HRP labeled neurones were always observed on the opposite superior colliculus if the injection sites reached layers deeper than the stratum oPticum. The locations of the labeled neurones corresponded roughly to the sites of HRP injections. However, no HRP labeled neurones were observed when the core of HRP deposites was restricted to layers superficial to the stratum griseum intermediale.2. Of all labeled neurones, 53.6% were located in the stratum griseum intermediale, 16.5% in the stratum opticum. The rest were in deeper layers. In no case were HRP labeled neurones observed in the stratum zonale or stratum griseum superficiale.3. Labeled neurones could be classified morphologically into vertical fusiform, horizontal fusiform and multipolar neurones.4. In addition to the visual cortex, labeled neurones were also found in the inferior colliculi, paralemniscal nuclei, dorsal nuclei of the lateral lemniscus, substantia nigrae and lateral tegmental nuclei bilaterally. Labeled neurones were also found in the ipsilateral ventral nucleus of the lateral geniculate body, contralatera pretectal area and reticular formation.

THE EFFERENT PROJECTIONS OF THE SUPERIOR COLLICULUS IN THE RAT.A STUDY WITH ARG AND WGA-HRP TECHNIQUES / 解剖学报

In the present study ~3H-Leucine or WGA-HRP was injected into the superior colliculus of one side in the rat.The terminal areas of the efferent projection fibers from the superior colliculus were examined. The efferent fibers of the superfical layer of the superior colliculus descended ipsilaterally to terminate in the parabigeminal nucleus(predominantly the dorsal and ventral part of the same side)and dorso-lateral part of the ipsilateral pontine nucleus.Ascending projections terminated to the medial geniculate nucleus,the posterior pretectal nucleus and latero-posterior nucleus of the thalamus(all bila- terally,but with ipsilateral predominance),the ipsilateral medial and lateral optic nuclei,and the dorsal and ventral lateral geniculate nucleus.In addition,labeled granules were also found in bilateral optic tracts and the optic chiasma. The efferent fibers of the middle and deep layers terminated to the ipsilateral central gray,the nucleus of Darkschewitsch,the interstitial nucleus of Cajal,the cuneiform nucleus and the contralateral superior colliculus.Ascending fibers ter- minated to the medial geniculate nucleus,the suprageniculate nucleus,the anterior- pretectal nucleus,the postero-lateral nucleus of the thalamus(all bilaterally,but more on the ipsilateral side),the parafascicular nucleus,the zona incerta,the ventral nucleus of the thalamus(all ipsilaterally).Descending fibers terminated to ipsilateral parabigeminal area and the parabigeminal nucleus,the dorso-lateral part of the pontine nucleus,the lateral part of the inferior colliculus,the reticular formation of the medulla oblongata and pons,and the lateral part of the inferior olive.The fibers terminated also to contralateral nuclei such as the parabigeminal nucleus,the medial part of the reticular formation of the medulla oblongata and ports,the medial accessory nucleus of the inferior olive,the anterior horn of the cervical spinal cord.