1
|
Bidell D, Feige ND, Triphan T, Müller C, Pauls D, Helfrich-Förster C, Selcho M. Photoreceptors for immediate effects of light on circadian behavior. iScience 2024; 27:109819. [PMID: 38770135 PMCID: PMC11103378 DOI: 10.1016/j.isci.2024.109819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Revised: 03/12/2024] [Accepted: 04/24/2024] [Indexed: 05/22/2024] Open
Abstract
Animals need to sharpen their behavioral output in order to adapt to a variable environment. Hereby, light is one of the most pivotal environmental signals and thus behavioral plasticity in response to light can be observed in diurnal animals, including humans. Furthermore, light is the main entraining signal of the clock, yet immediate effects of light enhance or overwrite circadian output and thereby mask circadian behavior. In Drosophila, such masking effects are most evident as a lights-on response in two behavioral rhythms - the emergence of the adult insect from the pupa, called eclosion, and the diurnal rhythm of locomotor activity. Here, we show that the immediate effect of light on eclosion depends solely on R8 photoreceptors of the eyes. In contrast, the increase in activity by light at night is triggered by different cells and organs that seem to compensate for the loss of each other, potentially to ensure behavioral plasticity.
Collapse
Affiliation(s)
- Daniel Bidell
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Natalie-Danielle Feige
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Tilman Triphan
- Department of Genetics, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Claudia Müller
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | - Dennis Pauls
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| | | | - Mareike Selcho
- Department of Animal Physiology, Institute of Biology, Leipzig University, Leipzig, Germany
| |
Collapse
|
2
|
Milićević N, Bergen AA, Felder-Schmittbuhl MP. Per1 mutation enhances masking responses in mice. Chronobiol Int 2022; 39:1533-1538. [PMID: 36189750 DOI: 10.1080/07420528.2022.2126321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Light can restrict the activity of an animal to a diurnal or nocturnal niche by synchronizing its endogenous clock (entrainment) which controls the sleep wake cycle. Light can also directly change an animal's activity level (masking). In mice, high illumination levels decrease activity, i.e. negative masking occurs. To investigate the role of core circadian clock genes Per1 and Per2 in masking, we used a 5-day behavioral masking protocol consisting of 3 h pulses of light given in the night at various illuminances (4-5 lux, 20 lux and 200 lux). Mice lacking the Per1 gene had decreased locomotion in the presence of a light pulse compared to wild-type, Per2 and Per1 Per2 double mutant mice. Per2 single mutant and Per1 Per2 double mutant mice did not show significantly different masking responses compared to wild-type controls. This suggests that Per1 suppresses negative masking responses in mice.
Collapse
Affiliation(s)
- Nemanja Milićević
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Arthur A Bergen
- Department of Human Genetics, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam, The Netherlands.,Department of Ophthalmology, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam, The Netherlands.,Queen Emma Centre for Personalized Medicine, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Marie-Paule Felder-Schmittbuhl
- Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Université de Strasbourg, Strasbourg, France
| |
Collapse
|
3
|
Evans SL, Leocadio-Miguel MA, Taporoski TP, Gomez LM, Horimoto A, Alkan E, Beijamini F, Pedrazzoli M, Knutson KL, Krieger JE, Vallada HP, Sterr A, Pereira AC, Negrão AB, von Schantz M. Evening preference correlates with regional brain volumes in the anterior occipital lobe. Chronobiol Int 2021; 38:1135-1142. [PMID: 33906520 DOI: 10.1080/07420528.2021.1912077] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Chronotype or diurnal preference is a questionnaire-based measure influenced both by circadian period and by the sleep homeostat. In order to further characterize the biological determinants of these measures, we used a hypothesis-free approach to investigate the association between the score of the morningness-eveningness questionnaire (MEQ) and the Munich chronotype questionnaire (MCTQ), as continuous variables, and volumetric measures of brain regions acquired by magnetic resonance imaging (MRI). Data were collected from the Baependi Heart Study cohort, based in a rural town in South-Eastern Brazil. MEQ and anatomical 1.5-T MRI scan data were available from 410 individuals, and MCTQ scores were available from a subset of 198 of them. The average MEQ (62.2 ± 10.6) and MCTQ (average MSFsc 201 ± 85 min) scores were suggestive of a previously reported strong general tendency toward morningness in this community. Setting the significance threshold at P > .002 to account for multiple comparisons, we observed a significant association between lower MEQ score (eveningness) and greater volume of the left anterior occipital sulcus (β = -0.163, p = .001) of the occipital lobe. No significant associations were observed for MCTQ. This may reflect the smaller dataset for MCTQ, and/or the fact that MEQ, which asks questions about preferred timings, is more trait-like than the MCTQ, which asks questions about actual timings. The association between MEQ and a brain region dedicated to visual information processing is suggestive of the increasingly recognized fluidity in the interaction between visual and nonvisual photoreception and the circadian system, and the possibility that chronotype includes an element of masking.
Collapse
Affiliation(s)
- S L Evans
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - M A Leocadio-Miguel
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK.,Department of Physiology and Behavior, Federal University of Rio Grande Do Norte, Natal, Rio Grande do Norte, Brazil
| | - T P Taporoski
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK.,Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil.,Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - L M Gomez
- Incor, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil
| | - Arvr Horimoto
- Incor, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil.,Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington, USA
| | - E Alkan
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - F Beijamini
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil.,Federal University of Fronteira Sul, Realeza, Paraná, Brazil
| | - M Pedrazzoli
- School of Arts, Sciences, and Humanities, University of São Paulo, São Paulo, São Paulo, Brazil
| | - K L Knutson
- Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - J E Krieger
- Incor, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil
| | - H P Vallada
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil
| | - A Sterr
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - A C Pereira
- Incor, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil
| | - A B Negrão
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil.,Incor, University of São Paulo School of Medicine, São Paulo, São Paulo, Brazil
| | - M von Schantz
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| |
Collapse
|
4
|
Rieger D, Stanewsky R, Helfrich-Förster C. Cryptochrome, Compound Eyes, Hofbauer-Buchner Eyelets, and Ocelli Play Different Roles in the Entrainment and Masking Pathway of the Locomotor Activity Rhythm in the Fruit Fly Drosophila Melanogaster. J Biol Rhythms 2016; 18:377-91. [PMID: 14582854 DOI: 10.1177/0748730403256997] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The fly Drosophila melanogaster possesses five photoreceptors and/or photopigments that appear to be involved in light reception and synchronization of the circadian clock: (1) the compound eyes, (2) the ocelli, (3) the Hofbauer-Buchner eyelets, (4) the blue-light photopigment cryptochrome, and (5) unknown photopigments in the clock-gene-expressing dorsal neurons. To understand the contributions of these photoreceptors and photopigments to synchronization, the authors monitored the flies' activity rhythms under artificial long and short days. They found that all the different photoreceptors and photo-pigments contribute significantly to entrainment under each photoperiod, but the compound eyes are especially important for entrainment to extreme photoperiods. The compound eyes are, furthermore, necessary for adjusting the phase of the activity rhythm, for distinguishing long days from constant light, and for the normal masking effects of light—namely, promotion of activity by lights-on and inhibition of activity by darkness. Cryptochrome is important for period lengthening under long days, although it is more important for entrainment to short days than to long days and is, furthermore, important for after effects of the photoperiod on the internal clock. The specific roles of the remaining photoreceptors are more difficult to assess.
Collapse
Affiliation(s)
- Dirk Rieger
- University of Regensburg, Institute of Zoology, 93040 Regensburg, Germany
| | | | | |
Collapse
|
5
|
Langel JL, Smale L, Esquiva G, Hannibal J. Central melanopsin projections in the diurnal rodent, Arvicanthis niloticus. Front Neuroanat 2015; 9:93. [PMID: 26236201 PMCID: PMC4500959 DOI: 10.3389/fnana.2015.00093] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 06/29/2015] [Indexed: 12/12/2022] Open
Abstract
The direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. Studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsically photosensitive (ipRGCs) in mediation of these acute responses to light. ipRGCs are photosensitive due to the expression of the photopigment melanopsin; these cells use glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP) as neurotransmitters. PACAP is useful for the study of central ipRGC projections because, in the retina, it is found exclusively within melanopsin cells. Little is known about the central projections of ipRGCs in diurnal species. Here, we first characterized these cells in the retina of the diurnal Nile grass rat using immunohistochemistry (IHC). The same basic subtypes of melanopsin cells that have been described in other mammals were present, but nearly 25% of them were displaced, primarily in its superior region. PACAP was present in 87.7% of all melanopsin cells, while 97.4% of PACAP cells contained melanopsin. We then investigated central projections of ipRGCs by examining the distribution of immunoreactive PACAP fibers in intact and enucleated animals. This revealed evidence that these cells project to the suprachiasmatic nucleus, lateral geniculate nucleus (LGN), pretectum, and superior colliculus. This distribution was confirmed with injections of cholera toxin subunit β coupled with Alexa Fluor 488 in one eye and Alexa Fluor 594 in the other, combined with IHC staining of PACAP. These studies also revealed that the ventral and dorsal LGN and the caudal olivary pretectal nucleus receive less innervation from ipRGCs than that reported in nocturnal rodents. Overall, these data suggest that although ipRGCs and their projections are very similar in diurnal and nocturnal rodents, they may not be identical.
Collapse
Affiliation(s)
- Jennifer L Langel
- Neuroscience Program, Michigan State University East Lansing, MI, USA
| | - Laura Smale
- Neuroscience Program, Michigan State University East Lansing, MI, USA ; Department of Psychology, Michigan State University East Lansing, MI, USA ; Department of Zoology, Michigan State University East Lansing, MI, USA
| | - Gema Esquiva
- Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen Copenhagen, Denmark ; Department of Physiology, Genetics and Microbiology, University of Alicante Alicante, Spain
| | - Jens Hannibal
- Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen Copenhagen, Denmark
| |
Collapse
|
6
|
Abstract
Sleep is expressed as a circadian rhythm and the two phenomena exist in a poorly understood relationship. Light affects each, simultaneously influencing rhythm phase and rapidly inducing sleep. Light has long been known to modulate sleep, but recent discoveries support its use as an effective nocturnal stimulus for eliciting sleep in certain rodents. “Photosomnolence” is mediated by classical and ganglion cell photoreceptors and occurs despite the ongoing high levels of locomotion at the time of stimulus onset. Brief photic stimuli trigger rapid locomotor suppression, sleep, and a large drop in core body temperature (Tc; Phase 1), followed by a relatively fixed duration interval of sleep (Phase 2) and recovery (Phase 3) to pre-sleep activity levels. Additional light can lengthen Phase 2. Potential retinal pathways through which the sleep system might be light-activated are described and the potential roles of orexin (hypocretin) and melanin-concentrating hormone are discussed. The visual input route is a practical avenue to follow in pursuit of the neural circuitry and mechanisms governing sleep and arousal in small nocturnal mammals and the organizational principles may be similar in diurnal humans. Photosomnolence studies are likely to be particularly advantageous because the timing of sleep is largely under experimenter control. Sleep can now be effectively studied using uncomplicated, nonintrusive methods with behavior evaluation software tools; surgery for EEG electrode placement is avoidable. The research protocol for light-induced sleep is easily implemented and useful for assessing the effects of experimental manipulations on the sleep induction pathway. Moreover, the experimental designs and associated results benefit from a substantial amount of existing neuroanatomical and pharmacological literature that provides a solid framework guiding the conduct and interpretation of future investigations.
Collapse
|
7
|
Acute effects of light on the brain and behavior of diurnal Arvicanthis niloticus and nocturnal Mus musculus. Physiol Behav 2014; 138:75-86. [PMID: 25447482 DOI: 10.1016/j.physbeh.2014.09.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 08/06/2014] [Accepted: 09/30/2014] [Indexed: 01/17/2023]
Abstract
Photic cues influence daily patterns of activity via two complementary mechanisms: (1) entraining the internal circadian clock and (2) directly increasing or decreasing activity, a phenomenon referred to as "masking". The direction of this masking response is dependent on the temporal niche an organism occupies, as nocturnal animals often decrease activity when exposed to light, while the opposite response is more likely to be seen in diurnal animals. Little is known about the neural mechanisms underlying these differences. Here, we examined the masking effects of light on behavior and the activation of several brain regions by that light, in diurnal Arvicanthis niloticus (Nile grass rats) and nocturnal Mus musculus (mice). Each species displayed the expected behavioral response to a 1h pulse of light presented 2h after lights-off, with the diurnal grass rats and nocturnal mice increasing and decreasing their activity, respectively. In grass rats light induced an increase in cFOS in all retinorecipient areas examined, which included the suprachiasmatic nucleus (SCN), the ventral subparaventricular zone (vSPZ), intergeniculate leaflet (IGL), lateral habenula (LH), olivary pretectal nucleus (OPT) and the dorsal lateral geniculate (DLG). In mice, light led to an increase in cFOS in one of these regions (SCN), no change in others (vSPZ, IGL and LH) and a decrease in two (OPT and DLG). In addition, light increased cFOS expression in three arousal-related brain regions (the lateral hypothalamus, dorsal raphe, and locus coeruleus) and in one sleep-promoting region (the ventrolateral preoptic area) in grass rats. In mice, light had no effect on cFOS in these four regions. Taken together, these results highlight several brain regions whose responses to light suggest that they may play a role in masking, and that the possibility that they contribute to species-specific patterns of behavioral responses to light should be explored in future.
Collapse
|
8
|
Fifel K, Cooper HM. Loss of dopamine disrupts circadian rhythms in a mouse model of Parkinson's disease. Neurobiol Dis 2014; 71:359-69. [PMID: 25171792 DOI: 10.1016/j.nbd.2014.08.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 08/06/2014] [Accepted: 08/20/2014] [Indexed: 12/18/2022] Open
Abstract
Although a wide range of physiological functions regulated by dopamine (DA) display circadian variations, the role of DA in the generation and/or modulation of these rhythms is unknown. In Parkinson's disease (PD) patients, in addition to the classical motor symptoms, disturbances of the pattern of daily rest/wake cycles are common non-motor symptoms. We investigated daily and circadian rhythms of rest/activity behaviors in a transgenic MitoPark mouse model with selective inactivation of mitochondrial transcription factor A (Tfam) resulting in a slow and progressive degeneration of DA neurons in midbrain structures. Correlated with this, MitoPark mice show a gradual reduction in locomotor activity beginning at about 20weeks of age. In a light-dark cycle, MitoPark mice exhibit a daily pattern of rest/activity rhythms that shows an age-dependent decline in both the amplitude and the stability of the rhythm, coupled with an increased fragmentation of day/night activities. When the circadian system is challenged by exposure to constant darkness or constant light conditions, control littermates retain a robust free-running circadian locomotor rhythm, whereas in MitoPark mice, locomotor rhythms are severely disturbed or completely abolished. Re-exposure to a light/dark cycle completely restores daily locomotor rhythms. MitoPark mice and control littermates express similar masking behaviors under a 1h light/1h dark regime, suggesting that the maintenance of a daily pattern of rest/activity in arrhythmic MitoPark mice can be attributed to the acute inhibitory and stimulatory effects of light and darkness. These results imply that, in addition to the classical motor abnormalities observed in PD, the loss of the midbrain DA neurons leads to impairments of the circadian control of rest/activity rhythms.
Collapse
Affiliation(s)
- Karim Fifel
- INSERM 846, Stem Cell and Brain Research Institute, Department of Chronobiology, 18 Avenue du Doyen Lépine, 69500 Bron, France; Laboratory of Neurophysiology, Molecular Cell Biology Department, Leiden University Medical Center, PO Box 9600 Mailbox S5-P. 2300 RC Leiden, The Netherlands.
| | - Howard M Cooper
- INSERM 846, Stem Cell and Brain Research Institute, Department of Chronobiology, 18 Avenue du Doyen Lépine, 69500 Bron, France.
| |
Collapse
|
9
|
Alteration of daily and circadian rhythms following dopamine depletion in MPTP treated non-human primates. PLoS One 2014; 9:e86240. [PMID: 24465981 PMCID: PMC3900505 DOI: 10.1371/journal.pone.0086240] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 12/11/2013] [Indexed: 12/24/2022] Open
Abstract
Disturbances of the daily sleep/wake cycle are common non-motor symptoms of Parkinson's disease (PD). However, the impact of dopamine (DA) depletion on circadian rhythms in PD patients or non-human primate (NHP) models of the disorder have not been investigated. We evaluated alterations of circadian rhythms in NHP following MPTP lesion of the dopaminergic nigro-striatal system. DA degeneration was assessed by in vivo PET ([(11)C]-PE2I) and post-mortem TH and DAT quantification. In a light∶dark cycle, control and MPTP-treated NHP both exhibit rest-wake locomotor rhythms, although DA-depleted NHP show reduced amplitude, decreased stability and increased fragmentation. In all animals, 6-sulphatoxymelatonin peaks at night and cortisol in early morning. When the circadian system is challenged by exposure to constant light, controls retain locomotor rest-wake and hormonal rhythms that free-run with stable phase relationships whereas in the DA-depleted NHP, locomotor rhythms are severely disturbed or completely abolished. The amplitude and phase relations of hormonal rhythms nevertheless remain unaltered. Use of a light-dark masking paradigm shows that expression of daily rest-wake activity in MPTP monkeys requires the stimulatory and inhibitory effects of light and darkness. These results suggest that following DA lesion, the central clock in the SCN remains intact but, in the absence of environmental timing cues, is unable to drive downstream rhythmic processes of striatal clock gene and dopaminergic functions that control locomotor output. These findings suggest that the circadian component of the sleep-wake disturbances in PD is more profoundly affected than previously assumed.
Collapse
|
10
|
Mammalian rest/activity patterns explained by physiologically based modeling. PLoS Comput Biol 2013; 9:e1003213. [PMID: 24039566 PMCID: PMC3764015 DOI: 10.1371/journal.pcbi.1003213] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Accepted: 07/23/2013] [Indexed: 12/15/2022] Open
Abstract
Circadian rhythms are fundamental to life. In mammals, these rhythms are generated by pacemaker neurons in the suprachiasmatic nucleus (SCN) of the hypothalamus. The SCN is remarkably consistent in structure and function between species, yet mammalian rest/activity patterns are extremely diverse, including diurnal, nocturnal, and crepuscular behaviors. Two mechanisms have been proposed to account for this diversity: (i) modulation of SCN output by downstream nuclei, and (ii) direct effects of light on activity. These two mechanisms are difficult to disentangle experimentally and their respective roles remain unknown. To address this, we developed a computational model to simulate the two mechanisms and their influence on temporal niche. In our model, SCN output is relayed via the subparaventricular zone (SPZ) to the dorsomedial hypothalamus (DMH), and thence to ventrolateral preoptic nuclei (VLPO) and lateral hypothalamus (LHA). Using this model, we generated rich phenotypes that closely resemble experimental data. Modulation of SCN output at the SPZ was found to generate a full spectrum of diurnal-to-nocturnal phenotypes. Intriguingly, we also uncovered a novel mechanism for crepuscular behavior: if DMH/VLPO and DMH/LHA projections act cooperatively, daily activity is unimodal, but if they act competitively, activity can become bimodal. In addition, we successfully reproduced diurnal/nocturnal switching in the rodent Octodon degu using coordinated inversions in both masking and circadian modulation. Finally, the model correctly predicted the SCN lesion phenotype in squirrel monkeys: loss of circadian rhythmicity and emergence of ∼4-h sleep/wake cycles. In capturing these diverse phenotypes, the model provides a powerful new framework for understanding rest/activity patterns and relating them to underlying physiology. Given the ubiquitous effects of temporal organization on all aspects of animal behavior and physiology, this study sheds light on the physiological changes required to orchestrate adaptation to various temporal niches.
Collapse
|
11
|
Abstract
Investigators typically study one function of the circadian visual system at a time, be it photoreception, transmission of photic information to the suprachiasmatic nucleus (SCN), light control of rhythm phase, locomotor activity, or gene expression. There are good reasons for such a focused approach, but sometimes it is advantageous to look at the broader picture, asking how all the parts and functions complete the whole. Here, several seemingly disparate functions of the circadian visual system are examined. They share common characteristics with respect to regulation by light and, to the extent known, share a common input neuroanatomy. The argument presented is that the 3 hypothalamically mediated effects of light for which there are the most data, circadian clock phase shifts, suppression of nocturnal locomotion (“negative masking”), and suppression of nocturnal pineal function, are regulated by a common photic input pathway terminating in the SCN. For each, light triggers a relatively fixed interval response that is irradiance-dependent, the effective stimulus can be very brief light exposure, and the response continues to completion in the absence of additional light. The presence of a triggered, fixed-length response interval is of particular importance to the understanding of the circuitry and mechanisms regulating circadian rhythm phase shifts because it implies that the SCN clock response to light is not instantaneous. It also may explain why certain stimuli (neuropeptide Y or novel wheel running) administered many minutes after light exposure are able to block light-induced phase shifts. The understanding of negative masking is complicated by the fact that it can be represented as a positive change, that is, light-induced sleep, not just as a reduction in locomotion. Acute nocturnal light exposure also induces adrenal hormone secretion and a rapid drop in body temperature, physiological responses that appear to be regulated similarly to the other light effects. The likelihood of a common regulatory basis for the several responses suggests that additional light-induced responses will be forthcoming and raises questions about the relationships between light, SCN cellular anatomy, the molecular clockworks of SCN neurons, and SCN throughput mechanisms for regulating disparate downstream activities.
Collapse
Affiliation(s)
- Lawrence P. Morin
- Department of Psychiatry, Stony Brook Medical Center, Stony Brook University, Stony Brook, NY
| |
Collapse
|
12
|
Kaneda K, Yanagawa Y, Isa T. Transient enhancement of inhibition following visual cortical lesions in the mouse superior colliculus. Eur J Neurosci 2012; 36:3066-76. [PMID: 22775357 DOI: 10.1111/j.1460-9568.2012.08224.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Numerous studies have investigated the effects of lesions of the primary visual cortex (V1) on visual responses in neurons of the superficial layer of the superior colliculus (sSC), which receives visual information from both the retina and V1. However, little is known about the changes in the local circuit dynamics of the sSC after receiving V1 lesions. Here, we show that surround inhibition of sSC neurons is transiently enhanced following V1 lesions in mice and that this enhancement may be attributed to alterations in the balance between excitatory and inhibitory inputs to sSC neurons. Extracellular recordings in vivo revealed that sSC neuronal responses to large visual stimuli were transiently reduced at about 1 week after visual cortical lesions compared with normal mice and that this reduction was partially recovered at about 1 month after the lesions. By using whole-cell patch-clamp recordings from sSC neurons in slice preparations obtained from mice that had received visual cortical lesions at 1 week prior to the recordings, we found cell type-dependent changes in the balance between excitation and inhibition. In non-GABAergic cells, inhibition predominated over excitation, whereas the excitation-inhibition balance did not change in GABAergic neurons. These results suggest that enhanced inhibition may be partially responsible for the reduced responses to large visual stimuli in some sSC neurons. Thus, we propose that the enhanced surround inhibition shortly after visual cortical lesions may prevent hyperexcitability in the sSC local circuit, contributing to reconstructing the finely tuned receptive field organization of sSC neurons after the visual cortical lesions.
Collapse
Affiliation(s)
- Katsuyuki Kaneda
- Department of Developmental Physiology, National Institute for Physiological Sciences, Okazaki, Japan.
| | | | | |
Collapse
|
13
|
Morin LP, Studholme KM. Millisecond light pulses make mice stop running, then display prolonged sleep-like behavior in the absence of light. J Biol Rhythms 2010; 24:497-508. [PMID: 19926809 DOI: 10.1177/0748730409349059] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Masking, measured as a decrease in nocturnal rodent wheel running, is a visual system response to rod/cone and retinal ganglion cell photoreception. Here, the authors show that a few milliseconds of light are sufficient to initiate masking, which continues for many minutes without additional photic stimulation. C57J/B6 mice were tested using flash stimuli previously shown to elicit large circadian rhythm phase shifts. Ten flashes, 2 msec each and equally distributed over 5 min, activate locomotor suppression that endures for an additional 25 to 35 min in the dark and does not differ in magnitude or duration from that elicited by 5-min saturating light pulse. Locomotor activity by mice without access to running wheels is also suppressed by light flashes. The effects of various light flash patterns on mouse locomotor suppression are similar to those previously described for hamster phase shifts. Video analysis of active mice indicates that light flashes initiated at ZT13 rapidly induce an interval of behavioral quiescence that lasts about 10 min at which time the animals assume a typical sleep posture that is maintained for an additional 25 min. Thus, the period coincident with light-induced wheel running suppression appears to consist of two distinct behavioral states, one interval during which locomotor quiescence is initiated and maintained, followed by a second interval characterized by behavioral sleep. Given this sequence effected by light stimulation, we suggest that it be referred to as "photosomnolence," the term reflecting upon both the nature of the stimulus and the associated behavioral change.
Collapse
Affiliation(s)
- L P Morin
- Department of Psychiatry, Stony Brook Medical Center, Stony Brook University, New York, USA.
| | | |
Collapse
|
14
|
Morin LP, Allen CN. The circadian visual system, 2005. ACTA ACUST UNITED AC 2006; 51:1-60. [PMID: 16337005 DOI: 10.1016/j.brainresrev.2005.08.003] [Citation(s) in RCA: 341] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2005] [Revised: 07/19/2005] [Accepted: 08/09/2005] [Indexed: 11/17/2022]
Abstract
The primary mammalian circadian clock resides in the suprachiasmatic nucleus (SCN), a recipient of dense retinohypothalamic innervation. In its most basic form, the circadian rhythm system is part of the greater visual system. 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. The IGL also provides a major input to the SCN, with a third major SCN afferent projection arriving from the median raphe nucleus. The last decade has seen a blossoming of research into the anatomy and function of the visual, geniculohypothalamic and midbrain serotonergic systems modulating circadian rhythmicity in a variety of species. There has also been a substantial and simultaneous elaboration of knowledge about the intrinsic structure of the SCN. Many of the developments have been driven by molecular biological investigation of the circadian clock and the molecular tools are enabling novel understanding of regional function within the SCN. The present discussion is an extension of the material covered by the 1994 review, "The Circadian Visual System."
Collapse
Affiliation(s)
- L P Morin
- Department of Psychiatry and Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY 11794, USA.
| | | |
Collapse
|
15
|
|
16
|
Mrosovsky N, Hattar S. Diurnal mice (Mus musculus) and other examples of temporal niche switching. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2005; 191:1011-24. [PMID: 16163543 DOI: 10.1007/s00359-005-0017-1] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/23/2005] [Accepted: 05/24/2005] [Indexed: 11/25/2022]
Abstract
Examples are presented of nocturnal animals becoming diurnal or vice versa as a result of mutations, genetic manipulations, or brain lesions. Understanding these cases could give insight into mechanisms employed when switches of temporal niche occur as part of the life cycle, or in response to circumstances such as availability of food. A two-process account of niche switching is advocated, involving both a change in clock-controlled outputs and a change in the direct response to light (i.e. masking). An emerging theme from this review is the suggestion that retinal inputs have a greater role in switching than suspected previously.
Collapse
Affiliation(s)
- N Mrosovsky
- Department of Zoology, University of Toronto, ON, M5S3G5, Canada.
| | | |
Collapse
|
17
|
Prichard JR, Fahy JL, Obermeyer WH, Behan M, Benca RM. Sleep responses to light and dark are shaped by early experience. Behav Neurosci 2005; 118:1262-73. [PMID: 15598135 DOI: 10.1037/0735-7044.118.6.1262] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Light regulates sleep timing through circadian entrapment and by eliciting acute changes in behavior. These behaviors are mediated by the subcortical visual system, retinorecipient nuclei distinct from the geniculocortical system. To test the hypothesis that early visual experience shapes light regulation of behavior, the authors recorded sleep in albino rats reared in continuous dark, continuous light, or a 12-hr light-dark cycle. Dark rearing strengthened and light rearing weakened acute responses to light, including light modulation of REM sleep, a marker for pretectal function in albino rats. However, neither dark nor light rearing altered daily amounts of wakefulness, non-REM sleep, or REM sleep. Thus, light and dark rearing might differentially affect the balance between acute and circadian responses to light that, in concert, govern sleep timing.
Collapse
Affiliation(s)
- J Roxanne Prichard
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | | | | | | | | |
Collapse
|
18
|
Redlin U, Hattar S, Mrosovsky N. The circadian Clock mutant mouse: impaired masking response to light. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2004; 191:51-9. [PMID: 15558289 DOI: 10.1007/s00359-004-0570-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 09/16/2004] [Accepted: 09/18/2004] [Indexed: 11/26/2022]
Abstract
Synchronization of an internal clock (entrainment) and a direct response to light (masking) are complementary ways of restricting activity of an animal to day or night. The protein CLOCK has an important role in the oscillatory mechanism of mammalian pacemakers. Our data show that it is also involved in masking responses. Mice with the Clock/Clock mutation reduced their wheel running less than wildtypes when given 1-h light pulses of light (2-1,600 lx) in the night. With dimmer lights (<2 lx), there were no significant differences between mutant and wildtype mice. Impaired masking responses to light in Clock/Clock mice were confirmed in tests with ultradian light-dark cycles (3.5:3.5 h and 1:1 h). Tests with pulses of light longer than 1 h revealed that, although the mutants responded more slowly to light, they sustained the suppression of activity over the course of the 3-h tests better than wildtypes.
Collapse
Affiliation(s)
- Uwe Redlin
- Department of Animal Physiology, Biological Institute, University of Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
| | | | | |
Collapse
|
19
|
Li X, Gilbert J, Davis FC. Disruption of masking by hypothalamic lesions in Syrian hamsters. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2004; 191:23-30. [PMID: 15449094 DOI: 10.1007/s00359-004-0569-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2004] [Revised: 07/28/2004] [Accepted: 08/12/2004] [Indexed: 10/26/2022]
Abstract
Negative masking of locomotor activity by light in nocturnal rodents is mediated by a non-image-forming irradiance-detection system in the retina. Structures receiving input from this system potentially contribute to the masking response. The suprachiasmatic nucleus (SCN) regulates locomotor activity and receives dense innervation from the irradiance-detection system via the retinohypothalamic tract, but its role in masking is unclear. We studied masking in adult Syrian hamsters (Mesocricetus auratus) with electrolytic lesions directed at the SCN. Hamsters were exposed to a 3.5:3.5 ultradian light/dark cycle and their wheel-running activity was monitored. Intact hamsters showed robust masking, expressing less than 20% of their activity in the light even though light and dark occurred equally during their active times. In contrast, hamsters with lesions showed, on average, as much activity in the light as in the dark. Tracing of retinal projections using cholera toxin beta subunit showed that the lesions damaged retinal projections to the SCN and to the adjacent subparaventricular zone. Retinal innervation outside the hypothalamus was not obviously affected by the lesions. Our results indicate that retinohypothalamic projections, and the targets of these projections, to the SCN and/or adjacent hypothalamic areas play an important role in masking.
Collapse
Affiliation(s)
- Xiaodong Li
- Department of Biology, Northeastern University, Boston, MA 02115, USA
| | | | | |
Collapse
|
20
|
Muscat L, Huberman AD, Jordan CL, Morin LP. Crossed and uncrossed retinal projections to the hamster circadian system. J Comp Neurol 2003; 466:513-24. [PMID: 14566946 DOI: 10.1002/cne.10894] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The hamster suprachiasmatic nucleus (SCN), site of the circadian clock, has been thought to be equally and completely innervated by each retina. This issue was studied in animals that had received an injection of the tracer cholera toxin subunit B (CTb) conjugated to Alexa 488 into the vitreous of one eye, with CTb-Alexa 594 injected into the other. Retinal projections to the SCN and other nuclei of the circadian system were simultaneously evaluated by using confocal laser microscopy. Each retina provides completely overlapping terminal fields throughout each SCN. Although SCN innervation by the contralateral retina is slightly denser than that from the ipsilateral retina, there are distinct SCN regions where input from one side is predominant, but not exclusive. A dense terminal field from the contralateral retina encompasses, and extends dorsally beyond, the central SCN subnucleus identified by calbindin-immunoreactive neurons. Surrounding the dense terminal field, innervation is largely derived from the ipsilateral retina. The densest terminal field in the intergeniculate leaflet is from the contralateral retina, which completely overlaps the ipsilateral projection. Most nuclei of the pretectum receive innervation largely, but not solely, from the contralateral retina, although the olivary pretectal nucleus has very dense patches of innervation derived exclusively from one retina or the other. Retina-dependent variation in terminal field density within the three closely examined nuclei may indicate areas of specialized function not previously appreciated. This issue is discussed in the context of the melanopsin-containing retinal ganglion cell projections to several nuclei in the circadian visual system.
Collapse
Affiliation(s)
- Louise Muscat
- Graduate Program in Neurobiology and Behavior, State University of New York at Stony Brook, Stony Brook, New York 11794, USA
| | | | | | | |
Collapse
|