Neuropeptide Y (NPY) is produced in the Intergeniculate leaflet (IGL) and known to mediate both photic and non-photic influences on the SCN. 
Further evidence for CB(1) involvement in hamster circadian rhythms was provided by immunohistochemical detection of CB(1) receptors in four separate nuclei comprising the principal components of the hamster circadian system: the suprachiasmatic nucleus, Intergeniculate leaflet of the thalamus, and dorsal and median raphe nuclei.
It is worth noting that oscillations within OPT were synchronized with the above-described oscillatory activity in the ipsilateral Intergeniculate leaflet (IGL).
The hypothalamic suprachiasmatic nucleus (SCN) and the thalamic Intergeniculate leaflet (IGL) are considered to be the main centers of the mammalian circadian timing system.
As in Gekko, major NPFF-ir cell groups were found in the diagonal band nucleus of Broca and in the hypothalamus, whereas additional cells were identified in the anterior olfactory nucleus, lateral and dorsal cortices, dorsal ventricular ridge, and the Intergeniculate leaflet formation.
We used c-fos expression as a marker for neuronal activation to determine whether these arousal procedures differentially activate two nonphotic inputs to the circadian system, the thalamic Intergeniculate leaflet (IGL; a proposed nonphotic gateway to the circadian clock) and the hypothalamic hypocretin system (which depolarizes arousal-related cell groups throughout the brain and innervates both the IGL and the peri-suprachiasmatic nucleus region).
The thalamic Intergeniculate leaflet (IGL), another component of the circadian regulatory system, did not show any TGF-alpha IR or any detectable daily variation in GFAP IR.
The Intergeniculate leaflet (IGL) has been shown to be a functional constituent of the circadian timing system.
In the rat, vasoactive intestinal peptide (VIP)- and gastrin-releasing peptide (GRP)-containing neurons are the dominant cell phenotypes of the ventral SCN, and these cells receive photic information from the retina and the Intergeniculate leaflet.
The Intergeniculate leaflet (IGL) is a very important component of the mammalian circadian timing system.
The Intergeniculate leaflet (IGL) is a flat thalamic nucleus that responds to retinal illumination, but also to non-photic input from many brain areas.
The Intergeniculate leaflet (IGL) is a region of the lateral geniculate complex that is part of the circadian system.
Nonphotic phase shifts of the circadian clock in mammals are mediated by the Intergeniculate leaflet (IGL) of the thalamus via a geniculohypothalamic projection to the suprachiasmatic nucleus.
Photic information to the SCN is mediated by pituitary adenylate-cyclase-activating polypeptide (PACAP)-containing retinal ganglion cells (RGCs), whereas non-photic input originates primarily from neuropeptide Y (NPY) cells in the ipsilateral thalamic Intergeniculate leaflet (IGL).
The results also show reduced sensitivity of flash-induced FOS response in the Intergeniculate leaflet compared with the SCN, contrary to studies using longer light stimuli.
Electrophysiological studies combined with local neurotoxic lesions were conducted on anaesthetized rats in order to determine whether the dorsal raphe nucleus (DRN) inhibits the Intergeniculate leaflet (IGL) of the lateral geniculate nucleus by means of innervation by serotonin-containing fibres.
The Intergeniculate leaflet (IGL) and its neuropeptide Y (NPY) projection to the main circadian clock, the suprachiasmatic nucleus (SCN), have been the focus of extensive research conducted, for the most part, on nocturnal rodent species.
These results support the hypothesis that nonphotic influences on circadian period serve a useful function when animals must respond to abruptly changing photoperiods and point to the NPYergic pathway from the Intergeniculate leaflet innervating the suprachiasmatic nucleus as a circuit mediating these effects..
The Intergeniculate leaflet received bilateral retinal innervation with overlap between ipsilateral and contralateral fibres.
Exp Eye Res 43:867-869) to quantitatively assess the effects of albinism on retinal projections to a number of subcortical visual nuclei including the ventral lateral hypothalamus (VLH), ventral lateral preoptic area (VLPO), olivary pretectal nucleus (OPN), posterior limitans (PLi), commissural pretectal area (CPA), Intergeniculate leaflet (IGL), ventral lateral geniculate nucleus (vLGN) and superior colliculus (SC).
This circadian rhythm is generated by intrinsic molecular mechanisms in the neurons of the SCN; however, the circadian clock is modulated by a wide variety of influences, including glutamate and pituitary adenylate cyclase-activating peptide (PACAP) from the retinohypothalamic tract, melatonin from the pineal gland, and neuropeptide Y from the Intergeniculate leaflet.
We next examined DARPP-32 expression in the retina and Intergeniculate leaflet (IGL), both of which convey light information to the suprachiasmatic nucleus (SCN), the locus of a master circadian clock, and in the SCN itself.
Photic information is relayed directly to the SCN via the retinohypothalamic tract (RHT) and indirectly via the geniculohypothalamic tract, which originates from retinally innervated cells of the thalamic Intergeniculate leaflet (IGL).
Additional cells were found in the anterior olfactory nucleus, lateral and dorsal cortices, dorsolateral septum, and diencephalic Intergeniculate leaflet formation.
In addition, the increased Hsp70 expression, which mainly localized in the Intergeniculate leaflet of LGN, was also observed by immunostaining in right LGN at the end of day 3 after the lesion.
In hamsters, the effects of light on circadian rhythms can be modulated by serotonergic input to the suprachiasmatic nucleus from the raphe nuclei and by neuropeptide Y containing afferents to the suprachiasmatic nucleus from the Intergeniculate leaflet in the thalamus. Both BMY 7378 and NAN-190 are thought to block serotonin release via acting as agonists at the 5-hydroxytryptamine 1A (5-HT1A) autoreceptors on cells in the raphe, and also block response of target cells by acting as antagonists at post-synaptic 5-HT1A receptors, for example, in the suprachiasmatic nuclei or the Intergeniculate leaflet.
They send axons directly to the suprachiasmatic nucleus (SCN), Intergeniculate leaflet (IGL), and olivary pretectal nucleus (OPN), thereby contributing to photic synchronization of circadian rhythms and the pupillary light reflex.
The role of the Intergeniculate leaflet of the thalamus (IGL) in photoperiod responsiveness was examined in a laboratory-selected line of photoperiod nonresponsive (NR) Siberian hamsters.
In the present studies, the contribution of the Intergeniculate leaflet to light energy integration by the hamster circadian rhythm system was evaluated. Fos protein is induced in Intergeniculate leaflet neurons at much lower irradiance levels than seen in suprachiasmatic nucleus neurons. Bilateral N-methyl-d-aspartate lesions of the Intergeniculate leaflet decreased phase response of the circadian locomotor rhythm to high irradiance and, in animals exposed to long duration light stimuli, reduced Fos induction in the suprachiasmatic nucleus. Normal photon integration, as indicated by attenuated rhythm phase shifts and Fos induction in suprachiasmatic nucleus cells in response to the energy in light stimuli, does not occur in the absence of the Intergeniculate leaflet and is likely to be a property of the circadian rhythm system, rather than solely of the suprachiasmatic nucleus. Anatomical analysis showed that virtually no Intergeniculate leaflet neurons projecting to the suprachiasmatic nucleus contain Fos induced by either light or locomotion in a novel wheel. The Intergeniculate leaflet is implicated in the normal assessment of light by the circadian rhythm system, but the circuitry by which either photic or non-photic information gains access to the suprachiasmatic nucleus may be more complex than previously thought..
It receives, among others, direct inputs from the retina and from the thalamic Intergeniculate leaflet (IGL).
A secondary component of the circadian visual system is the retinorecipient Intergeniculate leaflet (IGL) which has connections to many parts of the brain, including efferents converging on targets of the SCN.
In addition, c-Fos and PER-1 expression in the paraventricular thalamic nucleus (PVT) showed increased expression at palatable meal-time, while the Intergeniculate leaflet did not, suggesting that the PVT may be involved as an input pathway of palatable food-entrainment to the SCN.
In addition, two other nuclei which form part of the circadian system, the Intergeniculate leaflet of the thalamus and the raphe nuclei, also contain fibers and/or cell bodies immunoreactive for substance P.
The thalamic Intergeniculate leaflet (IGL) is involved in mediating effects of both photic and nonphotic stimuli on mammalian circadian rhythms.
Photic information is perceived by the retina and conveyed to the suprachiasmatic nucleus either directly by the retinohypothalamic tract or indirectly by the Intergeniculate leaflet and the geniculohypothalamic tract. injection of quipazine (10 mg/kg) were assessed in Lewis rats, which had received either radio-frequency lesions of the Intergeniculate leaflet or infusions of the serotonin neurotoxin 5,7-dihydroxytryptamine into the suprachiasmatic nucleus (25 microg) or bilateral enucleation. Lesions of Intergeniculate leaflet and serotonin afferents to the suprachiasmatic nucleus did not reduce the photic-like effects of quipazine, whereas bilateral enucleation and the subsequent degeneration of the retinohypothalamic tract abolished both the phase-shifting and the FOS-inducing effects of quipazine.
Neuropeptide-Y (NPY) cells in the Intergeniculate leaflet (IGL) are known to modulate effects of arousal on the mammalian circadian system.
At the level of the visual thalamus, expression of c-Fos in the Intergeniculate leaflet was higher during the subjective night as compared to the subjective day, although dark pulses had no robust effects on expression of c-Fos or P-ELK-1 in this structure.
A moderate plexus of Hcrt immunoreactive terminals has been described in the hamster Intergeniculate leaflet, part of the circadian rhythm system. This study investigated the origin of Hcrt-immunoreactive terminals in the Intergeniculate leaflet and determined whether melanin-concentrating hormone neurons also project to the Intergeniculate leaflet. The tracer, cholera toxin beta-subunit, was injected into the Intergeniculate leaflet of the golden hamster. No cholera toxin beta-subunit-immunoreactive cells also contained melanin-concentrating hormone and no melanin-concentrating hormone-immunoreactive processes were evident in the Intergeniculate leaflet. The results show that a small number of lateral hypothalamus cells containing Hcrt-immunoreactivity project to the Intergeniculate leaflet, but they are scattered rather than collected into a discrete group.
The Intergeniculate leaflet (IGL), homolog of the primate pregeniculate nucleus, modulates circadian rhythms.
Relaxin 3-immunoreactive fibers projected particularly densely in the septum, hippocampus, lateral hypothalamus and Intergeniculate leaflet of the thalamus.
Whereas immunoreactivity for all examined peptides was absent in the suprachiasmatic nucleus, dense and large orexin B-immunoreactive fibers and to a lesser extent melanin-concentrating hormone- and cocaine- and amphetamine-regulated transcript-immunoreactive fibers of smaller size were present in the Intergeniculate leaflet and raphe nucleus.
Similar results were obtained in the Intergeniculate leaflet (IGL) and ventral lateral geniculate (VLG).
Mammalian circadian rhythms are modulated by neuropeptide Y (NPY), a peptide contained in the projection from the Intergeniculate leaflet to the suprachiasmatic nuclei of the circadian pacemaker.
We investigated in young rats the effects of malnutrition on the main structures of the circadian timing system: retina, hypothalamic suprachiasmatic nuclei (SCN), thalamic Intergeniculate leaflet, retinohypothalamic- and geniculohypothalamic tracts.
In the lateral geniculate nucleus (LGN), light exposure appears responsible for FTL expression in dorsal nuclei, but not for expression in the ventral nuclei or the Intergeniculate leaflet.
Two pathways have been characterized through which entraining stimuli reach the SCN: the retinohypothalamic tract (RHT), which transmits light information from the retinae, and the geniculohypothalamic tract (GHT) from the Intergeniculate leaflet of the thalamus (IGL), which is involved in transmitting both photic and nonphotic cues.
Wildtype mice exposed to 2G demonstrated robust c-Fos expression in multiple autonomic, hypothalamic and limbic nuclei, including: the lateral septum, bed nucleus of the stria terminalis, amygdala, paraventricular hypothalamus, dorsomedial hypothalamus, arcuate, suprachiasmatic hypothalamus, Intergeniculate leaflet, dorsal raphe, parabrachial and locus coeruleus.
The slow oscillation circuit of the Intergeniculate leaflet seems to constitute a natural basic rhythm of the neuronal mechanism of mammalian biological clock. The activity of non-specific projections of the brain, whose terminals are present in the Intergeniculate leaflet, modulates the slow oscillation circuit of the leaflet neurons, without changing its oscillatory pattern, though. Our hypothesis predicts a role of the oscillatory activity of Intergeniculate leaflet neurons in facilitation the secretion of neuropeptides and neurohormones present in the very elements making up the mechanism of mammalian biological clock and structures linked to it.
The Intergeniculate leaflet could be identified between these two nuclei.
In the view of importance of Intergeniculate leaflet in circadian rhythms processes and lack of information about electrophysiological properties of isolated Intergeniculate leaflet (IGL) neurons, we carried out extracellular recordings of the spontaneous activity of rat IGL cells in vitro.
We also present evidence that orexin cells have projections to the Intergeniculate leaflet that appear to make contact with neuropeptide-Y cells.
The Intergeniculate leaflet (IGL) has widespread projections to the basal forebrain and visual midbrain, including the suprachiasmatic nucleus (SCN).
The Intergeniculate leaflet of the thalamus is, besides the suprachiasmatic nucleus of the hypothalamus, the other important neuronal element of the mammalian biological clock. The extracellularly recorded activity of neurons constituting the Intergeniculate leaflet, recorded in vivo, is characterized by distinct, very regular ultradian oscillations. Many, if not all, neurons of the suprachiasmatic nucleus and Intergeniculate leaflet contain GABA. In the present study we examined the effects of the GABA(A) receptor antagonist bicuculline and the chloride channel blocker picrotoxin on isoperiodic neuronal oscillations in the Intergeniculate leaflet of rats. We recorded extracellular multiple-unit neuronal activity from the Intergeniculate leaflet of anesthetized rats. In all the experiments, injection of GABA(A) receptor antagonists transiently disrupted the isoperiodic phasic discharge recorded from the Intergeniculate leaflet. These data suggest that GABA(A) receptors are involved in the generation of ultradian rhythmical neuronal oscillations in rat Intergeniculate leaflet..
In mammals, the thalamic Intergeniculate leaflet (IGL) conveys behavioral (non-photic) phase-resetting information to the circadian clock of the suprachiasmatic nucleus.
Neuropeptide Y (NPY) is delivered to the suprachiasmatic nuclei (SCN) circadian pacemaker via an input from the thalamic Intergeniculate leaflet.
Our results show that the PACAP-containing nerve fibres not only constituted the major projections to the SCN and the Intergeniculate leaflet of the thalamus but also had a large terminal field in the olivary pretectal nucleus.
The densest terminal field in the Intergeniculate leaflet is from the contralateral retina, which completely overlaps the ipsilateral projection.
Distinct c-fos expression was observed in the paraventricular nucleus, Intergeniculate leaflet and ventral lateral geniculate nucleus.
However, some ganglion cells forming the RHT bifurcate, sending axon collaterals to the Intergeniculate leaflet (IGL) through which light has secondary access to the circadian clock.
A possible pathway for the non-photic resetting of the clock is thought to originate from the Intergeniculate leaflet, which conveys information to the SCN through the geniculohypothalamic tract and utilizes among others neuropeptide Y (NPY) and GABA as neurotransmitters.
The photopigment melanopsin has recently been identified in intrinsically photosensitive retinal ganglion cells (RGCs) that project to the suprachiasmatic nucleus (SCN), Intergeniculate leaflet (IGL), and olivary pretectal nucleus, suggesting that melanopsin might influence a variety of irradiance-driven responses.
Finally, LS animals displayed a narrow band of labeled cell nuclei in the Intergeniculate leaflet (IGL) and throughout the anteroposterior extent of the superior colliculus (SC).
Retinal terminals are found in the Intergeniculate leaflet and the "dorsal cap" of the ventral lateral geniculate.
A possible pathway for non-photic resetting of the clock is thought to generate from the Intergeniculate leaflet, which conveys information to the suprachiasmatic nucleus (SCN) through the geniculohypothalamic tract and utilises neuropeptide Y (NPY) as its primary neurotransmitter.Interactions between light and NPY were investigated during the early (2 h after activity onset) and late (6 h after activity onset) night in male Syrian hamsters.
Despite these changes, cell density in the suprachiasmatic nucleus (SCN) and Intergeniculate leaflet (IGL) did not differ significantly between epileptic and control groups.
Melanopsin ganglion cells convey information regarding general levels of environmental illumination to the suprachiasmatic nucleus, the Intergeniculate leaflet, and the pretectum.
Thalamic neurons projecting to the tectum were observed in the ventral lateral geniculate nucleus, the Intergeniculate leaflet and the interstitial nuclei of the tectothalamic tract, and the nucleus of the decussatio supraoptica ventralis.
The suprachiasmatic nucleus (SCN) receives its serotonergic input from the median raphe nucleus, while the Intergeniculate leaflet (IGL) receives serotonergic innervation from the dorsal raphe nucleus (DRN).
The Intergeniculate leaflet (IGL) is considered involved in nonphotic shifting of the circadian clock through a direct connection, the geniculo-hypothalamic tract.
Novel wheel exposure mediates its effects via the Intergeniculate leaflet, which conveys information to the SCN and utilises neuropeptide Y (NPY) as its primary neurotransmitter.
An intense accumulation of PACAP-immunoreactive (-IR) nerve fibers was observed throughout the hypothalamus, in the amydaloid and extended amygdaloid complex, in the anterior and paraventricular thalamic nuclei, in the Intergeniculate leaflet, in the pretectum, and in several brainstem nuclei, such as the parabrachial nucleus, the sensory trigeminal nucleus, and the nucleus of the solitary tract.
We investigated effects of the electrical lesion and/or chemical inactivation of Intergeniculate leaflet (IGL) neurons on the ultra-slow isoperiodic neuronal oscillation of the contralaterally located IGL.
We hypothesized that regions of the pretectum respond to light with robust and region-specific Fos activation, similar to the suprachiasmatic nucleus and Intergeniculate leaflet. We found three regions in the pretectum (the olivary pretectal nucleus, posterior limitans, and a region homologous to the hamster commissural pretectal nucleus), and two regions in the lateral geniculate complex (the Intergeniculate leaflet and ventral lateral geniculate nucleus) that demonstrated significant Fos activation in response to light.
The mammalian circadian time-keeping system is established by two major neural structure: the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and the Intergeniculate leaflet (IGL) of the thalamus.
This patterned activity is compared to the one observed in the thalamic structure--the Intergeniculate leaflet of the lateral geniculat nucleus (IGL). Slow bursting activity of the Intergeniculate leaflet cells is suggested to have a same function as has patterned firing of hypothalamic cells.
Several studies have demonstrated a variety of effects of Intergeniculate leaflet (IGL) lesions on circadian rhythm regulation.
C-jun-immunopositive cells were mainly localised in the Intergeniculate leaflet and vLGN.
The circadian pacemaker receives afferent input from many brain regions, one of which is the Intergeniculate leaflet of the thalamus. These results imply that enkephalins released from the Intergeniculate leaflet onto components of the suprachiasmatic pacemaker may be capable of inhibiting the responsiveness of the pacemaker to photic input arriving from the retina.
Neurons in a subset of retinorecipient nuclei [ i.e., suprachiasmatic nucleus (SCN), Intergeniculate leaflet, olivary pretectal nucleus (OPN), and lateral terminal nucleus] and autonomic nuclei [ i.e., paraventricular hypothalamic nucleus and Edinger-Westphal nucleus (EW)] are labeled by late stages of infection.
Paraventricular thalamic nucleus, Intergeniculate leaflet and zona incerta directly innervate SCN.
Additionally, the Intergeniculate leaflet (IGL), which innervates the SCN, is known to modulate the retinal photic input to the SCN.
We investigated effects of bilateral electrolytic Intergeniculate leaflet (IGL) lesions (IGLX) on circadian rhythms of the wheel-running activity in mice kept under constant darkness conditions (DD).
CB expression occurred early (before eye-opening) in the relay neurons of the Intergeniculate leaflet, parvocellular portion of the ventral lateral geniculate nucleus and OPT relating to ambient vision mediated by W-like retinal ganglion cells.
Neuropeptide Y (NPY) that is released from the Intergeniculate leaflet of the lateral geniculate body to the SCN, acts in the SCN to advance circadian phase in the subjective day via the NPY Y2 receptor.
Other prominent modulatory inputs to the SCN include a serotonergic projection from the raphe nuclei and a neuropeptide Y (NPY) input from the Intergeniculate leaflet.
The circadian pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) receives photic information directly via the retinohypothalamic tract (RHT) and indirectly from retinally innervated cells in the thalamic Intergeniculate leaflet (IGL) that project to the SCN.
The Intergeniculate leaflet (IGL) of the lateral geniculate complex has widespread, bilateral, and reciprocal connections with nuclei in the subcortical visual shell.
The thalamic Intergeniculate leaflet contained a plexus of immunoreactive orexin A fibres throughout its rostro-caudal extent.
In hamsters, one such influence, running in a novel wheel, is mediated in part by the pathway extending from neuropeptide-Y (NPY)-containing cells within the Intergeniculate leaflet (IGL) of the thalamus to the hypothalamic suprachiasmatic nucleus (SCN). Sections through the Intergeniculate leaflet were processed for immunohistochemical labeling of Fos and NPY.
Subcortical visual nuclei, including the ventral lateral geniculate nucleus and Intergeniculate leaflet, pretectal area, and superior colliculus, and the subthalamus (zona incerta, fields of Forel) also project to the PHA.
The Intergeniculate leaflet (IGL) and the ventral lateral geniculate nucleus (VLG) are ventral thalamic derivatives within the lateral geniculate complex.
The Intergeniculate leaflet (IGL) modulates photic and nonphotic entrainment of circadian rhythms in nocturnal species, but nothing is known about its role in diurnal species.
Phase shifts of wheel-running activity rhythms and gene expression in the SCN, Intergeniculate leaflet, and paraventricular nucleus of the thalamus were assessed in animals following either of the training conditions or the control procedures.
The suprachiasmatic nuclei (SCN) of the hypothalamus and the Intergeniculate leaflet (IGL) of the thalamic lateral geniculate complex are two main oscillators for circadian timing system.
A projection from the Intergeniculate leaflet of the thalamus to the circadian pacemaker in the suprachiasmatic nucleus is believed to mediate some types of non-photic phase-shifting stimuli.
Unilateral PRV 152 injections into the vitreous body of the hamster eye transsynaptically infected a restricted set of retinorecipient neurons including neurons in the hypothalamic suprachiasmatic nucleus (SCN) and the Intergeniculate leaflet (IGL) of the thalamus.
The present study examined the pattern of induction of c-Fos and JunB in the SCN and Intergeniculate leaflet (IGL) of rats housed in constant conditions, under light-dark cycles, or in dark-adapted light-stimulated animals.
In this study, we investigated the distribution of the 5-HT(5A) receptors in four neural components of the circadian timing system (the SCN, the Intergeniculate leaflet, and the median and dorsal raphe nuclei), in the Syrian hamster.
Input to the SCN from the Intergeniculate leaflet contains neuropeptide Y (NPY) and can modulate photic responses.
It is believed that afferent projections from the Intergeniculate leaflet of the thalamus to circadian pacemaker cells within the suprachiasmatic nucleus mediate the phase shifting effects of some non-photic stimuli. In hamsters, many of the Intergeniculate leaflet afferents contain enkephalin, yet the role of opioids in producing non-photic phase shifts in hamsters has not been reported.
How does light information finally reach to the clock is not fully understood in many vertebrate groups? In mammals, however, the light information from the retina to the clock (the hypothalamic suprachiasmatic nuclei, SCN) is relayed through the retino-hypothalamic tract (RHT) which originates from the retinal ganglion cells, and through the geniculo-hypothalamic tract (GHT) which originates from the photically responsive cells of a portion of the lateral geniculate nucleus (LGN), called the Intergeniculate leaflet (IGL).
To clarify the role of glial fibrillary acidic protein (GFAP)-expressed glial cells in the circadian clock, we examined GFAP expression in the suprachiasmatic nucleus (SCN) and the Intergeniculate leaflet (IGL) under various lighting conditions in mice.
In view of the dynamic changes in DRN neuronal activity incumbent with the daily sleep-activity cycle, and its functional linkages to the SCN and Intergeniculate leaflet, the DRN could serve to provide behavioral/arousal state information to various sites comprising the brain circadian system..
Here, we report the photic regulation of melatonin receptor density and mRNA expression in the suprachiasmatic nuclei and pars tuberalis of pinealectomized Siberian hamsters and the implication in this control of either the circadian clock or the Intergeniculate leaflet. (4) Intergeniculate leaflet lesion totally inhibits the mt1 mRNA expression rise in the suprachiasmatic nuclei, while it has no effect on the light-induced increase in mt1 mRNA in the pars tuberalis. However, the light-induced increase in melatonin receptor density is totally prevented by the Intergeniculate leaflet lesion in the pars tuberalis. These results show that: (1) the photic regulations of mt1 mRNA expression and receptor density are independent of each other in both the suprachiasmatic nuclei and pars tuberalis; and (2) the circadian clock and the Intergeniculate leaflet are implicated in the photic regulation of melatonin receptors but their level of action differs totally between the suprachiasmatic nuclei and pars tuberalis..
The hamster suprachiasmatic nucleus (SCN) is innervated by a dense plexus of enkephalin-containing axons originating from cells in the Intergeniculate leaflet (IGL) of the thalamus.
Our paper is the first to describe ultradian rhythmic neuronal oscillation in the Intergeniculate leaflet (IGL) of the rat.
Sleep deprivation mimicked the effects of exercise on basal c-fos expression in two components of the circadian system, suppressing basal Fos immunoreactivity in the SCN, and increasing Fos in the Intergeniculate leaflet.
The hamster Intergeniculate leaflet (IGL), part of the circadian rhythm regulatory system, has very extensive interconnections with subcortical visual nuclei.
We examined the possible involvement of the thalamic Intergeniculate leaflet (IGL) in the phase-shifting properties of 8-OH-DPAT injections at CT7.
The Intergeniculate leaflet, a major component of the subcortical visual system, has been shown to be essential for certain aspects of circadian rhythm regulation. We now report that midbrain visual nuclei afferent to the Intergeniculate leaflet are also components of the hamster circadian rhythm system. Loss of connections between the Intergeniculate leaflet and visual midbrain or neurotoxic lesions of pretectum or deep superior colliculus (but not of the superficial superior colliculus) blocked phase shifts of the circadian activity rhythm in response to a benzodiazepine injection during the subjective day. A variety of environmental stimuli may gain access to the circadian clock mechanism through subcortical nuclei projecting to the Intergeniculate leaflet and, via the final common path of the geniculohypothalamic tract, from the leaflet to the suprachiasmatic nucleus..
Populations of cells distributed homogeneously in the ventral lateral geniculate nucleus and Intergeniculate leaflet were also found to express mRNA for estrogen receptor beta and progesterone receptor. The present observation together with the recent demonstration of a direct pathway between the Intergeniculate leaflet and hypothalamic neuroendocrine cells indicate that integration of hormonal and photic stimuli in the central regulation of endocrine mechanisms occurs outside of the hypothalamus in the lateral geniculate body..
The neural connections and neurotransmitter content of the suprachiasmatic nucleus and Intergeniculate leaflet have been characterized thoroughly in only a few mammalian species, primarily nocturnal rodents. Specifically, this report details: (i) the distribution of six neurotransmitters commonly found in the suprachiasmatic nucleus and Intergeniculate leaflet; (ii) the retinohypothalamic tract; (iii) the geniculohypothalamic tract; and (iv) retinogeniculate projections in O. Neuropeptide Y-immunoreactive and [ Met]enkephalin-immunoreactive cells were identified in the Intergeniculate leaflet and ventral lateral geniculate nucleus, as were neuropeptide Y-immunoreactive, [ Met]enkephalin-immunoreactive, serotonin-immunoreactive and substance P-immunoreactive fibers and terminals. The retinohypothalamic tract innervated both suprachiasmatic nuclei equally; in contrast, retinal innervation to the lateral geniculate nucleus, including the Intergeniculate leaflet, was almost exclusively contralateral. Bilateral electrolytic lesions that destroyed the Intergeniculate leaflet depleted the suprachiasmatic nucleus of virtually all neuropeptide Y- and [ Met]enkephalin-stained fibers and terminals, whereas unilateral lesions reduced fiber and terminal staining by approximately half. Thus, [ Met]enkephalin-immunoreactive and neuropeptide Y-immunoreactive cells project equally and bilaterally from the Intergeniculate leaflet to the suprachiasmatic nucleus via the geniculohypothalamic tract in degus.
A number of investigators have focused attention on the Intergeniculate leaflet (IGL) and the geniculohypothalamic tract (GHT) that mediate the effects of nonphotic stimuli on SCN activity and how these pathways interact with photic information being transmitted to the SCN..
Syrian hamsters with Intergeniculate leaflet or sham lesions were given tests with a series of light pulses of gradually decreasing intensities. Hamsters with Intergeniculate leaflet lesions showed a significantly greater suppression of their wheel running in response to light than the sham-lesioned animals. It is concluded that the Intergeniculate leaflet in the Syrian hamster cannot be of paramount importance for masking of locomotor activity by light but may play a modulating role..
To examine the contribution of the thalamic Intergeniculate leaflet (IGL) and its NPY-immunoreactive projection in the extension of the duration of the photosensitive phase of the SCN, male Syrian hamsters received electrolytic lesions of the IGL.
We have investigated the effect of the laterodorsal tegmental (LDTg) stimulation on evoked potentials in the Intergeniculate leaflet (IGL) of the rat, in order to characterize how non-specific systems of the brain, whose activity indicates the influence of non-photic information, impact the activity of the IGL.
The Intergeniculate leaflet, which projects to the SCN via the geniculohypothalamic tract, receives serotonergic innervation from the dorsal raphe nucleus, and the SCN receives its serotonergic input from the median raphe nucleus.
Hamsters with lesions of the thalamic Intergeniculate leaflet do not exhibit constant light-induced disruptions in rhythmicity. The present study demonstrates, however, that the Intergeniculate leaflet does not mediate these effects in rats. Rats with bilateral electrolytic Intergeniculate leaflet lesions showed the same rate of disruption of circadian temperature rhythms as did sham-operated animals, housed under constant light. We also show that, unlike Intergeniculate leaflet-lesioned rats, rats treated neonatally with monosodium glutamate exhibit neuropeptide Y fiber staining in the suprachiasmatic nucleus, indicating that the geniculohypothalamic tract is functionally intact following monosodium glutamate treatment.
Strong Fos induction was observed in the SCN and the Intergeniculate leaflet (IGL).
Using dual-immunocytochemistry for PACAP and the in vivo tracer Cholera toxin subunit B (ChB), intense PACAP immunoreactivity (PACAP-IR) was observed in retinal afferents at the rat SCN as well as in the Intergeniculate leaflet (IGL) of the thalamus.
niloticus, the anatomy of two neural structures that play important roles in the control of circadian rhythms, the suprachiasmatic nucleus (SCN) and the Intergeniculate leaflet (IGL).
Expression of the immediate early genes c-fos and fosB was examined by immunocytochemistry in the suprachiasmatic nucleus (SCN), the Intergeniculate leaflet (IGL) of the thalamus, and the medial pretectal area of hamsters that ran vigorously in the novel wheel and would have phase-shifted.
Photic information is transmitted to the SCN directly from the retina via the retinohypothalamic tract (RHT) and indirectly from the retinorecipient Intergeniculate leaflet (IGL) via the geniculohypothalamic tract (GHT).
Light pulse-induced c-fos expression in the SCN and the Intergeniculate leaflet (IGL) were unaffected by MKC-242 (3 mg kg(-1), i.p.).
Both TRZ and NW access require an intact Intergeniculate leaflet (IGL) to modulate circadian rhythm phase.
The anatomy of the SCN and its major afferents from the retina (glutamate, Substance P), raphe (serotonin) and Intergeniculate leaflet (neuropeptide Y) of the thalamus are presented with a special emphasis on the interaction of these inputs with the circadian timekeeping mechanism.
The Intergeniculate leaflet (IGL) is a distinct division of the lateral geniculate complex that participates in the regulation of the circadian rhythm through its projections to the circadian pacemaker located in the suprachiasmatic nuclei of the hypothalamus.
Photic information that entrains circadian rhythms is transmitted to the suprachiasmatic nucleus (SCN) from the retina and from the retinorecipient Intergeniculate leaflet (IGL).
Scattered patches of p75NTR immunoreactivity are present in the Intergeniculate leaflet (IGL).
Two components of the circadian system, the suprachiasmatic nucleus (SCN) (site of the circadian clock) and the Intergeniculate leaflet (IGL), receive serotonergic projections from the median raphe nucleus and the dorsal raphe nucleus, respectively.
In rodents, the circadian rhythm generated by the hypothalamic suprachiasmatic nucleus (SCN) is modulated by two types of phenomena: photic phase-shifts, mediated by the retinohypothalamic pathway and non-photic phase-shifts mediated by the projection of the Intergeniculate leaflet (IGL) to the SCN which contains the neuropeptide Y (NPY).
We present here the terminal morphology of retinal axons in the lateral geniculate body and superior colliculus, verifying earlier studies, and also document novel findings on the configuration of retinal axon endings in the ventral nucleus of the lateral geniculate body, Intergeniculate leaflet, suprachiasmatic nucleus, and in the nuclei of the accessory optic tract.
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 Intergeniculate leaflet (IGL), a major constituent of the circadian visual system, is one of 12 retinorecipient nuclei forming a "subcortical visual shell" overlying the diencephalic-mesencephalic border. Male hamsters received stereotaxic, iontophoretic injections of the retrograde tracer, cholera toxin beta fragment, or the anterograde tracer, Phaseolus vulgaris-leucoagglutin, into nuclei of the pretectum (medial, commissural, posterior, olivary, anterior, nucleus of the optic tract, posterior limitans), into the superior colliculus, or into the visual thalamic nuclei (lateral posterior, dorsal lateral geniculate, Intergeniculate leaflet, ventral lateral geniculate).
Syrian hamsters bearing lesions of the Intergeniculate leaflet of the thalamus remain able to entrain and phase-shift to light, but the lesions block completely entrainment by serial arousal, even though lesioned animals continue to respond acutely to the arousing cue.
In addition, the inhibitory effects of systemically administered 8-OH-DPAT were unaffected by either radiofrequency-induced lesions of the Intergeniculate leaflet or 5,7-dihydroxytryptamine-induced lesions of serotonergic projections to the SCN.
Components of the circadian system, the suprachiasmatic nucleus and the Intergeniculate leaflet receive serotonin input from the raphe nuclei. To study the relation between serotonin afferents and light-activated cells in the suprachiasmatic nucleus and Intergeniculate leaflet, we used immunostaining for the serotonin transporter and for the transcription factor, Fos. In the Intergeniculate leaflet, serotonin transporter immunostaining identified vertically-oriented columns of fibres. Exposure to light for 30 min during the dark phase of the light cycle induced Fos expression in the ventrolateral suprachiasmatic nucleus and Intergeniculate leaflet regions.
This dissociation was prevented by lesions of the Intergeniculate leaflet of the ventral lateral geniculate nucleus. Our results suggest that MAOI treatment weakens the coupling between oscillators that comprise the circadian pacemaker, and augments the disruptive effects of continuous light acting via the Intergeniculate leaflet region of the ventral lateral geniculate nucleus.
GABA is considered to be the principal neurotransmitter of the mammalian circadian system, being present in the suprachiasmatic nuclei and the Intergeniculate leaflet.
After injection of the retrograde tracer fluorogold into these hypothalamic projection sites in parallel with bilateral enucleation, retrogradely labeled perikarya were restricted to the Intergeniculate leaflet. This study provides morphological evidence for a signaling pathway from the retina through the Intergeniculate leaflet to hypothalamic cells that participate in neuroendocrine regulations.
The present study investigated the daily expression of Fos-like immunoreactivity (Fos-ir) and light pulse-induced Fos-ir in the SCN, the Intergeniculate leaflet (IGL) and the paraventricular thalamic nucleus (PVT) in calorie-restricted rats fed 2 h after the onset of light and in controls fed ad libitum.
After Fluoro-Gold injections into the SCN, retrogradely labeled neurons are present in a number of brain areas, including the infralimbic cortex, the lateral septum, the medial preoptic area, the subfornical organ, the paraventricular thalamus, the subparaventricular zone, the ventromedial hypothalamic nucleus, the posterior hypothalamic area, the Intergeniculate leaflet, the olivary pretectal nucleus, the ventral subiculum, and the median raphe nuclei. Similarly, areas that receive photic input, such as the retina, the Intergeniculate leaflet, and the pretectal area, densely innervate the ventral SCN but provide only minor innervation of the dorsal SCN.
The ventral lateral geniculate nucleus (vLGN) and the Intergeniculate leaflet (IGL) are retinorecipient subcortical nuclei.
In nocturnal rodents, exposure to light results in an increase in Fos expression in two regions that receive direct retinal input: the suprachiasmatic nuclei (SCN) of the hypothalamus and the Intergeniculate leaflet (IGL) of the thalamus.
Blind C57BL/6j mice were run in treadmills for 3 hr/d for 3-10 weeks after receiving radio-frequency lesions of the SCN or the Intergeniculate leaflet (IGL, the source of SCN NPY) or infusions of the 5-HT neurotoxin 5,7-DHT into the SCN area.
In addition to direct retinohypothalamic innervation, the SCN receive a prominent projection of fibers from the Intergeniculate leaflet (IGL) of the thalamus, the geniculohypothalamic tract (GHT), some of which contain the neurotransmitter, neuropeptide Y (NPY).
To examine the contribution of the thalamic Intergeniculate leaflet (IGL) and its NPY-immunopositive projection, the geniculo-hypothalamic tract to non-photic entrainment by arousal, male Syrian hamsters received lesions of the IGL (IGLX) which ablated NPY-immunoreactivity in the SCN.
To examine possible sites of action of 8-OH-DPAT, 8-OH-DPAT (0.5 microg (100 nl) or 1.0 microg (200 nl)) was microinjected into the Intergeniculate leaflet, dorsal raphe nuclei, and the median raphe nucleus at circadian time 7. Significant phase advances were observed after microinjection into the dorsal raphe and median raphe but not the Intergeniculate leaflet.
In addition, we examined the distribution of immunostaining for these subunits in a second structure of the mammalian circadian system, the Intergeniculate leaflet of the thalamus since it also is thought to receive glutamatergic input from the retina and is important in the entrainment of circadian rhythms. The results indicated that all of the subunits investigated (GluR1, GluR2/3, GluR4, GluR5/6/7, and NMDAR1) were present in the suprachiasmatic nucleus and that all but GluR4 were present in the Intergeniculate leaflet. The distribution of immunoreactivity for these subunits in the hamster suprachiasmatic nucleus and Intergeniculate leaflet differed from that reported in the rat. The presence of these subunits in the suprachiasmatic nucleus and Intergeniculate leaflet implies the presence of functional NMDA and non-NMDA receptors in these structures that may have a role in photic entrainment of the circadian pacemaker..
The aim of this work was to examine the effects of lesions of the Intergeniculate leaflet (IGL) on the tau of these two activity rhythms.
We used dual immunocytochemistry for pituitary adenylate cyclase-activating peptide (PACAP) and the in vivo tracer cholera toxin subunit B and observed intense PACAP-immunoreactivity (PACAP-IR) in retinal afferents in the rat SCN as well as in the Intergeniculate leaflet (IGL) of the thalamus.
In order to characterize how suprachiasmatic nuclei (SCN) neurons integrate its visual inputs, extracellular responses from SCN and adjacent hypothalamic neurons were recorded after stimulation of either the retina, the Intergeniculate leaflet (IGL) or both simultaneously.
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).
The presence of NPY and 5-HT fibers suggests that the SCN receives afferent projections from the Intergeniculate leaflet and from the raphe nuclei, respectively.
The hypothalamic suprachiasmatic nucleus and the thalamic pregeniculate nucleus (which includes the Intergeniculate leaflet) comprise the circadian visual system in the primate brain. These data suggest that calbindin D-28k could represent a reliable neuronal marker for structures of the circadian visual system in marmosets and provide anatomical information on the primate equivalent of the rodent Intergeniculate leaflet..
Immunohistochemical observation was performed in the suprachiasmatic nucleus (SCN) and the Intergeniculate leaflet (IGL) of hereditary bilaterally microphthalmic rats without the optic nerve on both sides.
Following injection of [ 3H]D-aspartate into the SCN, neurons were retrogradely labeled in the infralimbic cortex, the lateral septal nucleus, the paraventricular thalamic nucleus, the medial preoptic area, the ventromedial, dorsomedial and posterior hypothalamic nuclei, the zona incerta, the Intergeniculate leaflet and the ventral subiculum.
By contrast, in food-restricted rats with electrolytic lesion of Intergeniculate leaflet (IGL: IGLX group), there was only a 1 h phase-advance of the acrophase of temperature rhythm.
The anatomy of the SCN and its major afferents from the retina, raphe, and Intergeniculate leaflet (IGL) of the thalamus are considered, with a special emphasis on the effects of afferent interaction on the circadian timekeeping system.
These regions also gave rise to projections to the superior colliculus, as did the Intergeniculate leaflet.
Light-induced Fos in neurons of the Intergeniculate leaflet (IGL) is not well-characterized.
Ambient light alters the level of the transcriptional regulatory protein c-Fos in the suprachiasmatic nucleus, the site of an endogenous circadian clock in mammals, and in one other retino-recipient area, the Intergeniculate leaflet of the lateral geniculate complex. Complementing previous work by ourselves and others on the photic and temporal regulation of c-Fos expression in the suprachiasmatic nucleus, the present studies investigated c-Fos regulation in the rat Intergeniculate leaflet, revealing some important differences between the two brain regions. In the Intergeniculate leaflet, the levels of c-fos mRNA (by in situ hybridization) and immunoreactive c-Fos protein (by immunohistochemistry) were elevated by light pulses administered either during the subjective day or subjective night. By combining c-Fos immunofluorescence with stereotaxic injections of the retrograde tract tracer FluoroGold, we found photically-induced c-Fos in 15% of Intergeniculate leaflet neurons projecting to the suprachiasmatic nucleus and in 34% of those projecting to the contralateral Intergeniculate leaflet. Intergeniculate leaflet cells that express c-Fos after photic stimulation appear to represent a functionally-defined population that does not correspond to anatomically-defined categories based on connectivity or peptidergic phenotype..
The data suggest that the medial zone of the cat vLGN may be homologous to the rodent Intergeniculate leaflet (IGL)..
It receives three main inputs from the retina (glutamate), the Intergeniculate leaflet (NPY) and the dorsal raphe (serotonin).
Neurons of two nuclei previously shown to be sources of tectal input, the nucleus pretectalis (PT) and the Intergeniculate leaflet (IGL; Brecha, 1978), were found to be NPY+.
Two anatomical components of this system, the suprachiasmatic nucleus (SCN) and the Intergeniculate leaflet (IGL), receive serotonergic input from midbrain raphe nuclei.
Neuropeptide Y (NPY)-containing fibers project from the Intergeniculate leaflet to the suprachiasmatic nucleus.
We studied the effects of drugs related to melatonin on neuronal firing activity in the suprachiasmatic nucleus, Intergeniculate leaflet and other brain areas in urethane-anesthetized Syrian hamsters. Iontophoresis of melatonin dose dependently depressed spontaneous and light-evoked activity of cells in the suprachiasmatic nucleus and Intergeniculate leaflet, while iontophoresis of S20098 was relatively ineffective, probably because it is a poorly charged compound. S20928 (2.0-10 mg/kg, i.p.) alone decreased firing rates of light-sensitive cells by 25-50% for 5-30 min in the suprachiasmatic nucleus and Intergeniculate leaflet; however, low doses (< 2.0 mg/kg) of S20928 partially blocked the effects of melatonin agonists on most cells. S20928 may have mixed agonist/antagonist properties, but at low doses appears to function as an antagonist at melatonin receptors in the suprachiasmatic nucleus and Intergeniculate leaflet..
A relatively small number of thick serotonergic fibers were observed at the time of birth, distributed more densely in the ventral portion of the nucleus and in the Intergeniculate leaflet than in the dorsal lateral geniculate nucleus.
Electrical stimulation of the Intergeniculate leaflet (IGL) region in hamsters can induce expression of Fos-like immunoreactivity (lir) in a restricted portion of the dorsolateral suprachiasmatic nucleus (SCN).
The areas examined include the principal circadian pacemaker, the suprachiasmatic nucleus (SCN), and areas that receive important SCN input including the Intergeniculate leaflet (IGL), subparaventricular zone (SPVZ), paraventricular hypothalamic nucleus (PVH), the retrochiasmatic area (RCh) and the paraventricular nucleus of the thalamus (PVT).
Double immunocytochemistry was used to determine the neurochemical phenotype of cells in the Intergeniculate leaflet that were activated by these stimuli. Both the nonphotic and the photic phase-shifting stimuli induced the expression of c-fos in the Intergeniculate leaflet compared to unstimulated controls. These findings suggest that the NPY pathway from the Intergeniculate leaflet to the suprachiasmatic nucleus carries information about nonphotic events..
Simultaneous stainings for neuropeptide Y (NPY) and tyrosine hydroxylase (TH) immunoreactivity showed that they are not colocalized, neither in the SCN fibers nor in the Intergeniculate leaflet (IGL) neurons, site of origin of the NPY projection to the SCN.
The aim of the present work was to study, in rats, the effects of lesions of the thalamic Intergeniculate leaflet (IGL) and the deep pineal/lamina intercalaris region (DP) on the diurnal profile of N-acetylserotonin (NAS) and on the nocturnal pineal reactivity to acute retinal light stimulation (1 or 15 min). These results suggest that: (1) the Intergeniculate leaflet has a role in regulating the amplitude of the diurnal rhythm of pineal NAS production rather than its phase entrainment to light-dark cycle.
Expression of Fos protein in the suprachiasmatic nucleus (SCN) and Intergeniculate leaflet (IGL) is considered a cellular correlate of light-induced phase-shift of circadian rhythms in rodents.
The paraventricular nucleus of the thalamus (PVT) receives input from all major components of the circadian timing system, including the suprachiasmatic nucleus (SCN), the Intergeniculate leaflet and the retina.
Ascending fibres project bilaterally to the Intergeniculate leaflet, the ventral part of the lateral geniculate nucleus and ipsilaterally to the anterior pretectal nucleus.
A medial group gives rise to two sets of neurons, one that migrates to the Intergeniculate leaflet and another that develops in the medial nucleus reuniens.
Injection of HRP into the unilateral vitreous body demonstrated that the terminal labeling of the optic projections was seen bilaterally in the suprachiasmatic nucleus (SCH), the ventral (GLv) and dorsal (GLd) lateral geniculate nuclei, the Intergeniculate leaflet (IGL), the medial pretectal nucleus (NTOM) of the pretectum (PT) and the superficial layer of the superior colliculus (CS), with contralateral predominance, and only contralaterally labeled terminals were found in the lateroposterior thalamic nucleus (LP), the lateral pretectal nucleus (NTOL) of the PT, the dorsal (DTN) and medial (MTN) terminal nuclei of the accessory optic system (AOS).
NPY-LI structures were also observed in the metathalamic Intergeniculate leaflet and in a variety of telencephalic structures including the cerebral cortex, caudate nucleus putamen, lateral septal nucleus, bed nucleus of the stria terminalis and amygdala..
The present study examined the effects of LL on circadian rhythms and on light-induced expression of Fos protein in the SCN, Intergeniculate leaflet (IGL), and ventrolateral geniculate nucleus (vLGN) in adult rats treated neonatally with monosodium glutamate (MSG).
The suprachiasmatic nucleus (SCN) receives a direct photic projection from the retina, the retinohypothalamic tract (RHT), and an indirect photic projection from the Intergeniculate leaflet of the thalamus, the geniculohypothalamic tract (GHT).
The effects of light pulses on activity onset and offset were assessed in Intergeniculate leaflet- and ventral lateral geniculate nucleus-lesioned Syrian hamsters with a precise onset and offset of circadian wheel-running activity. Similar results were obtained in a selected group of intact animals indicating that Intergeniculate leaflet- and ventral lateral geniculate nucleus-lesioned hamsters provide a good model to investigate the effects of light on circadian onset and offset of running-wheel activity..
Previous studies have indicated that the neuropeptide Y input from the Intergeniculate leaflet of the lateral geniculate nucleus to the suprachiasmatic nucleus is the final part of a non-photic phase shifting pathway to pacemakers in hamsters, or that neuropeptide Y is necessary for other pathways to be effective.
We investigated the localization of receptors to SP in the suprachiasmatic nucleus of the hypothalamus (SCN) and in the Intergeniculate leaflet of the thalamus (IGL) of the rat and hamster using in situ hybridization histochemistry and immunohistochemistry.
No labeled cells were observed in the medial septal nucleus, Intergeniculate leaflet, and ventral lateral geniculate nucleus, which are also known to project to the SCN.
The Intergeniculate leaflet (IGL) is an integral part of the adult circadian visual system.
The geniculohypothalamic tract arises from neurons of a specialized subdivision of the lateral geniculate complex, the Intergeniculate leaflet. The Intergeniculate leaflet and geniculohypothalamic tract appear to provide integrated photic and non-photic input to the suprachiasmatic nuclei to modulate pacemaker function.
The projection from the Intergeniculate leaflet (IGL) to the suprachiasmatic nucleus (SCN) appears to be an important part of the mechanism mediating such phase shifts.
The Intergeniculate leaflet (IGL) is an integral part of the circadian visual system.
The Intergeniculate leaflet (IGL) receives retinal input and sends afferents to the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator.
Phase shifts normally induced by injections of Tz can be blocked by lesions of the Intergeniculate leaflet (IGL) of the thalamus.
In the rat, the RHT has two components, one which projects to the SCN and the Intergeniculate leaflet of the thalamus and has no known peptide content and one which projects to the SCN and, perhaps, to the olivary pretectal nucleus and contains substance P (SP).
These results were obtained only if the tracer was delivered into the Intergeniculate leaflet of the lateral geniculate nucleus (IGL).
Neuropeptide Y-containing fibers project from the Intergeniculate leaflet of the lateral geniculate nucleus to the suprachiasmatic nucleus.
The major afferent projections of the suprachiasmatic nuclei originate in the retina and the Intergeniculate leaflet of the lateral geniculate nucleus and are important in the entrainment of endogenous circadian rhythms. A characteristic feature of the suprachiasmatic nucleus and the Intergeniculate leaflet of the thalamus is that they are bilaterally innervated from the retina.
The retina also sends a bilateral projection to the suprachiasmatic nucleus; the Intergeniculate leaflet; the pretectum; and the medial, lateral, and dorsal terminal nuclei of the accessory optic system.
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