All data are presented as the mean ± SEM Unless otherwise noted,

All data are presented as the mean ± SEM. Unless otherwise noted, comparisons between two groups were analyzed using unpaired Student’s t tests, while multigroup comparisons were analyzed using two-way ANOVA followed by Bonferroni post hoc tests. A p < 0.05 was considered significant. We thank Dr. David Ginty for providing TrkBF616A mice. We thank Dr. J. Victor Nadler and Dr. Richard D. Mooney for critical discussions and reading of the manuscript. Daniella Cordero assisted in EEG and video reading. Wei-Hua Qian assisted GS-7340 datasheet in animal breeding and genotyping. This work was supported by NINDS grants NS56217 and NS060728 (J.O.M.). “
“One prominent aspect of neuronal morphogenesis is the series of

steps by which axons become progressively more specialized. Initially, one of several short neurites becomes an axon; the others become dendrites (Barnes and Polleux, 2009). Next, the axon elongates, often over long distances (O’Donnell et al., 2009). Once in the target region, the axon branches to form arbors that allow it to synapse onto numerous postsynaptic cells (Schmidt

and Rathjen, 2010 and Gibson and Ma, 2011). The branches then selectively synapse on appropriate synaptic partners, and form nerve terminals specialized for neurotransmitter release (Jin and Garner, 2008). Later still, terminal arbors are sculpted Trametinib concentration or rearranged leading to the definitive pattern of connectivity (Luo and O’Leary, 2005). Extrinsic factors in the environment through which the axon grows regulate each of these steps. For many of the steps, guidance and patterning molecules have been identified (Kolodkin and Tessier-Lavigne, 2011), but less is Carnitine palmitoyltransferase II known about the intracellular pathways that respond to and integrate these cues. We, and others, previously showed that a set of three Ser/Thr kinases, LKB1, SAD-A, and SAD-B, control polarization and axon specification in forebrain neurons (Kishi et al., 2005, Barnes et al., 2007 and Shelly et al., 2007). LKB1 is a multifunctional kinase that regulates cellular

energy homeostasis, polarity and cell proliferation by phosphorylating and activating kinases of the AMPK subfamily, of which SAD-A and SAD-B (also known as Brsk2 and Brsk1, respectively) are members (Alessi et al., 2006). SAD kinases are selectively expressed in the mammalian nervous system and are orthologs of C. elegans Sad-1, a regulator of vesicle clustering at active zones ( Kishi et al., 2005, Inoue et al., 2006 and Crump et al., 2001). Deletion of LKB1 or both SAD-A and SAD-B causes a loss of polarity in cortical and hippocampal neurons ( Kishi et al., 2005, Barnes et al., 2007 and Shelly et al., 2007). Here, we asked whether LKB1 and SAD kinases regulate axonal development in other neurons. Surprisingly, LKB1 and SAD kinases are not required for early stages of axon formation in the spinal cord or brainstem.

The early plasticity and subsequent stability of DLS activity dur

The early plasticity and subsequent stability of DLS activity during automatic runs could reflect such early action learning. It was only after the second devaluation procedure was imposed that the stability of the task-bracketing pattern was broken along with extinction of running. This finding is in accord with prior evidence that the DLS pattern, once formed, is insensitive to an instruction cue change requiring new learning (Kubota et al., 2009) but decays when reward is omitted altogether (Barnes et al., 2005). Under conditions of at least partial reinforcement, the acquired DLS pattern remains intact. It is within these conditions that well-learned behaviors can be maintained under some

habitual control. Our findings suggest, however, that it is the balance of this sensorimotor striatal activity with value-sensitive limbic IL activity that may ultimately determine the extent of habitual performance. Such dynamics find more could, in disease or addictive states, provide a route by which behaviors become overly repetitive. Rats (n = 22) were trained on a T-maze task requiring them to respond to auditory instruction cues by turning into maze end-arms to receive reward (chocolate milk or sucrose, each paired with a distinct cue). Training proceeded over daily sessions through task acquisition (72.5% accuracy for 2 days) and overtraining (10+ more days). For reward devaluation, rats received three pairings

of home-cage intake with lithium chloride

injection and were returned to the task for an unrewarded probe session I-BET-762 mouse and subsequent rewarded sessions. Task events were controlled by computer software (MED-PC or MATLAB). Behavior was monitored by in-maze photobeams and an overhead charge-coupled device camera recording at 30 Hz. Neuronal activity was recorded from 12–24 independently drivable tetrodes using a Cheetah acquisition system (Neuralynx). Single units were isolated using Offline Sorter (Plexon) not and, for DLS recordings, sorted into neuronal subtypes. Task-related spike activity exceeded 2 SD above a baseline period for three 30 ms bins within ±200 ms of a task event. Analysis were conducted on behavior- and learning-related changes in task-related population sizes, spike magnitude, spiking variability, and task-bracketing activity scores (spiking around the cue period subtracted from mean spiking around run start and run stop). Optogenetic perturbation during 10 overtraining days, from run start to stop, was accomplished using bilateral IL injection of AAV5-CaMKIIα-eNpHR3.0-EYFP (halorhodopsin) or AAV5-CaMKIIα-EYFP (control), duel-ferrule fiber implants (Doric Lenses), laser light (2.5–4 mW/side; 593.5 nm; OEM Laser Systems), and a pulse generator (AMPI). ANOVA, linear regression, and neuronal spike distribution statistics assessed behavioral and neuronal activity changes, with significance set at p < 0.05.

Each well of a 24-well tissue-culture plate (Corning, UK) was sup

Each well of a 24-well tissue-culture plate (Corning, UK) was supplemented with 106 J774.2 cells and

incubated (2 h, 37 °C, 5% CO2) after which the medium was replaced with 1 ml/well of fresh cRPMI. A 5 mg/ml suspension of 0–20% CaP PCMCs loaded with 0.4% BSA-FITC or the equivalent concentration of soluble BSA-FITC were prepared in cRPMI. A 0.5 ml aliquot was added to each well and incubated (1 h, 37 °C, 5% CO2) whilst protected from light. To stop uptake, cells were washed twice with ice-cold PBS and suspended in 1 ml of ice-cold PBS. Cells were centrifuged for 10 min at 118 × g, the resultant pellet click here suspended in 4 ml of fixing solution [1% formaldehyde in PBS] and samples stored at 4 °C whilst protected from light. Uptake of fluorescent particles was determined using a FACSCanto

II flow cytometer (BD Biosciences). Sterile glass coverslips were coated with 0.2% gelatine in PBS and air-dried. An aliquot of 106 J774.2 cells in 2 ml of cRPMI BMN 673 research buy was added to each well (24-well tissue-culture plate) containing coated coverslips and incubated (3 h, 37 °C, 5% CO2) for cell attachment. Cells were then incubated (1 h, 37 °C, 5% CO2) with the appropriate antigen formulation and washed twice with PBS-A, then fixed (300 μl/well, 4% paraformaldehyde in PBS-A) and incubated (20 min, rt). Cells were permeabilised by incubation with PBS-A containing 0.2% BSA and 0.2% Triton MRIP X-100 and secondary incubation with PBS-A containing 5% BSA. After washing, the actin cytoskeleton was stained with AlexaFluor594-conjugated phalloidin (Life Technologies, UK) for 5 min prior to nuclear staining with 4′,6-diamidino-2-phenylindole (DAPI) for 3 min. After washing, the coverslips were mounted onto glass microscope slides and cell fluorescence visualised using a Leica SP2 AOBS laser-scanning confocal microscope (40×, NA 1.25 oil immersion lens). Images were analysed using IMARIS software v7.4.2 (Bitplane, Switzerland). Statistical analysis was performed using GraphPad Prism5 software. Gaussian distribution of the data was assessed using the

D’Agostino and Pearson omnibus normality test. Responses between several groups were compared by one-way analysis of variance (ANOVA) with Tukey’s, Bonferroni’s or Dunn’s correction, as appropriate. Where data failed to pass the normality test, non-parametric comparison between several groups was by the Kruskal–Wallis test. Comparison of data between two groups was performed using Student’s t-test. Statistical significance was defined as p < 0.05. SEM showed that soluble PCMCs loaded with antigen without CaP (0% CaP PCMCs) were planar, irregular discs (Fig. 1A) but, as the CaP loading increased, the particles became more regular rod-like structures (Fig. 1B and C). This change in morphology was antigen-independent over the 0.2–0.4% antigen loading used (not shown).

02) (Figure S4) Thus, in contrast to long-range synchronization,

02) (Figure S4). Thus, in contrast to long-range synchronization, which predicted perception before the stimulus became ambiguous, changes in power rather seemed to reflect a consequence Ibrutinib of the establishment of the different percepts. In summary, our results demonstrate highly structured large-scale cortical networks of oscillatory synchronization: up to seven anatomically confined cortical areas synchronized their activities across several centimeters and multiple processing stages along the sensorimotor pathways. Synchronization within these networks was temporally well localized to the cognitive event of interest and was linked to specific frequency

ranges that differed across multiple octaves between networks (beta and gamma). Although much progress has been made studying neural population activity in individual cortical areas, it remains difficult to characterize large-scale neural interactions across the entire brain. This is largely due to methodological problems. On the one hand, it is difficult to simultaneously record from multiple brain regions in invasive experiments. On the other hand, although EEG and MEG sample neural activity from a large part of the brain, estimating cortical interaction on the basis of these extracranial signals remains difficult. A further important obstacle is the lack of tools to efficiently analyze

cortico-cortical interactions in a high-dimensional space over with the ensuing substantial multiple-comparison problem. Our cluster-permutation–based approach may provide a valuable new tool to address

see more these problems and to identify large-scale networks of interacting sources. In particular, it goes beyond imaging neural activity across a singular cortical space and provides a framework to characterize interactions in a full pairwise cortico-cortical space. In principle, the approach is not limited to the study of synchrony, as demonstrated here, but may be applied to any bivariate parameter defined across the brain. Furthermore, the approach can be applied to a broad spectrum of experimental designs, including simple condition differences as well as complex parametric models. Moreover, no a priori assumptions need to be made about the structure of cortical networks. The method is robust to oversampling of the pairwise interaction space. This allows for directly imaging the extent of networks in space, time, and frequency. This approach well complements recent applications of graph-theoretical measures that provide powerful tools to quantify the global structural properties of large-scale connectivity (Bressler and Menon, 2010, Hagmann et al., 2008 and Palva et al., 2010). Our results provide strong evidence for the functional relevance of synchronization within the identified large-scale cortical networks.

A range of bacterial levels was observed among samples within

A range of bacterial levels was observed among samples within check details a single time point, sometimes resulting in a standard deviation that was larger than the average counts, in part, a product of the combination of enumerated and assigned values for samples ( Table 2). This is an inherent limitation of microbiological

data. Gathering statistically sound plate count data is only possible when using higher inoculum concentrations, but such treatments are less likely to mimic natural contamination scenarios. Lowering the limit of detection for enumeration by filtration or including MPN determinations would add time and cost to the analysis but should be considered for future studies. Differences among samples in nut shell topography and shell integrity (e.g., small Galunisertib molecular weight cracks) may also have contributed to this variation by influencing our ability to remove inoculated organisms with our sampling procedure. Bacterial decline at each sampling point during storage

was calculated by subtracting the levels determined at the sampling point from the levels measured at the beginning of storage. The declines among the three genera were similar at all sampling points except for three; greater declines were observed in L. monocytogenes populations than in Salmonella and E. coli O157:H7 populations at 27, 83, and 97 days of storage. Over 97 days of ambient storage, declines of Salmonella and E. coli O157:H7 were estimated to be less than 1 log CFU/nut and the decline of L. monocytogenes was 2 log CFU/nut. These declines were less than the 2.8- to 3.8-log decline observed for Salmonella Enteritidis PT 30 on walnuts inoculated at 10 or 7.5 log CFU/nut, respectively, and stored for a similar length of time

(83 to 139 days) ( Table 1). These data are comparable to previous studies with other tree nuts; as populations decrease to near the standard LOD the rate of decline slows ( Beuchat and Heaton, Sclareol 1975, Beuchat and Mann, 2010a, Blessington et al., 2012 and Kimber et al., 2012). During the 97-day storage period, 78 inshell nuts were sampled per genera; of these, 73 Salmonella-, 66 E. coli O157:H7-, and 66 L. monocytogenes-inoculated nuts were positive by plate count or enrichment. Plate counts of at least 1 log CFU/nut were obtained for 49 Salmonella-, 23 E. coli O157:H7-, and 31 L. monocytogenes-inoculated nuts. At all time points during storage after the initial plating, all samples were subjected to a primary enrichment. Enriched broths were streaked onto selective/differential media for confirmation if enumerated values were below the LOD or if the previous enrichment was negative. An additional number of walnuts were positive after secondary or tertiary enrichment ( Table 2); 14 nut samples (6% of the 234 nut samples evaluated) required additional enrichment beyond the initial 24 h for positive isolation. Recovery of pathogens from dry foods presents a challenge as the cells may be severely injured.

Abnormal interactions between

mHTT and transcription fact

Abnormal interactions between

mHTT and transcription factors may play a prominent role in neuropathology, and, as they are expected to be quite pleiotropic, it suggests both an intriguing explanation for the wide-ranging systems disrupted in HD neurons as well as a promising target for therapy. The reduction of neurotransmitter receptors in the HD striatum (Glass et al., 2000, Pavese et al., 2003 and Weeks et al., 1996) is one of the earliest observed symptoms, and mHTT is known to interact with or sequester numerous transcription factors (Boutell et al., 1999, Dunah et al., 2002, Huang et al., 1998, Nucifora et al., 2001 and Steffan Dasatinib ic50 et al., 2000). The advent of more advanced transcriptional profiling in the last 10 years along with a bevy of mouse models of HD have provided ample opportunity for assaying this dysregulation and attempting therapies. Microarray transcriptional profiles were compiled for R6/2 mice both before (6 weeks) and after (12 weeks) onset of overt motor symptoms. Approximately 1.5% of transcripts displayed altered levels at each age, with a majority (75%) displaying decreased expression (Luthi-Carter et al., 2000). Many of these transcriptional changes were verified in N171-82Q Pfizer Licensed Compound Library price mice though they were not shared

by YAC72 mice (Chan et al., 2002). Further analysis from this group demonstrated that 12-week-old R6/2, 16-week-old N171-82Q, and 12-month-old Histone demethylase animals modeling DRPLA (a disorder resulting from polyglutamine expansion in the Atrophin-1 gene) all show significant overlap of cerebellar profiles (Luthi-Carter et al., 2002). That cerebellar tissue and also laser-capture microdissected interneurons

(Zucker et al., 2005) of R6/2 mice demonstrate transcriptional dysregulation suggests that this phenomenon is not unique to the cells most vulnerable to degeneration, nor are inclusion-bearing cells more prone to transcriptionally altered neurotransmitter receptor levels (Sadri-Vakili et al., 2006). What has been particularly striking is the significant similarities in transcriptional profiles of most genetic HD mouse models tested, both among each other and with human HD. Simultaneous profiling of R6/1, R6/2, HdhQ150, HdhQ92, and YAC128 mice demonstrated that every model correlated significantly with every other model and with human HD, with the caveat that the strains had to be aged appropriately (Kuhn et al., 2007). Other studies have reached similar conclusions (Hodges et al., 2008 and Strand et al., 2007). Given that the global transcriptional changes are more commonly downregulations than upregulations in HD model mice (Luthi-Carter et al., 2000) and that there are altered chromatin dynamics associated with repressed transcription (increased methylation and decreased acetylation) (Stack et al.

, 2008 and Shitamukai et al , 2011) Moreover, a novel type of se

, 2008 and Shitamukai et al., 2011). Moreover, a novel type of self-renewing progenitor cells that have no contact with the ventricular surface, termed outer radial glial cells (oRGs), has recently been described in the cerebral cortex in several mammalian species, including mice, in which they are rare, and ferrets and humans, in which they are abundant (Fietz and Huttner, 2011 and Lui et al., 2011). oRGs retain a basal process

that may be important for the reception of signals maintaining the progenitor state, such as Notch signal. However, they are devoid Ibrutinib supplier of an apical process and apically located polarity molecules such as CD133, Par3, or aPKC (Fietz and Huttner, 2011 and Lui et al., 2011). So, why do NPCs that express Foxp4 and lose their apical process attachment (but presumably retain a basal process) differentiate rather than continue to self renew? One possibility is that a neuronal fate determinant tethered to apical junctions in neuroepithelial NPCs is released by the disruption of adherens buy Thiazovivin junctions and thus becomes free

to promote differentiation (Bultje et al., 2009). Consistent with this model, Rousso et al. (2012) show that the Notch pathway inhibitor Numb is released into the cytoplasm when Foxp4 is overexpressed or N-cadherin activity is antagonized. They suggest that the resulting inhibition of Notch signaling might contribute to the initiation of neuronal differentiation that follows adherens junction disruption. In contrast, a change of plane of division, such as that occurring in LGN mutant mice (Konno et al., 2008), might segregate the daughter cell losing the apical domain away from the apically localized neuronal

fate determinant and thus TCL allow this cell to remain proliferative. Further investigation should provide fascinating insights on how Foxp genes control the fate of neuroepithelial NPCs and contribute to the generation of other types of progenitors found in mammalian cortices. “
“Although most cells are measured in microns, neurons, especially peripheral neurons, can be a meter long and therefore make extreme demands on our molecular motors. Small wonder that mutations in ubiquitous motor proteins give rise to specifically neurological diseases. Two such diseases, Perry syndrome and the distal hereditary motor neuropathy 7B (HMN7B), are examples of that phenomenon and their cell biological basis has been examined by two papers in this issue of Neuron ( Moughamian and Holzbaur, 2012 and Lloyd et al., 2012). Although their symptoms are quite different, both diseases are caused by mutations in the same domain of the dynactin subunit p150Glued. By approaching the function of this domain in Drosophila neurons and mouse dorsal root ganglion (DRG) neurons, the present studies illuminate the function of p150Glued in axonal transport. Axonal microtubules are uniformly polarized with their plus ends away from the soma.

Our data suggest that the molecular mechanisms for stabilization

Our data suggest that the molecular mechanisms for stabilization of the AIS in adult neurons in vivo are distinct from the mechanisms used Z-VAD-FMK in vivo for assembly of the AIS in developing neurons. We propose

a dynamic model for maintenance of the mature AIS, whereby Nfasc186 is constitutively required for anchoring of new protein components to the AIS complex. To test whether proteins known to be constituents of the initial segment complex could cluster appropriately in the absence of the Neurofascins (the neuronal isoform Nfasc186 and the glial isoform Nfasc155), we examined the cerebella of wild-type and Neurofascin null mice at P6. NrCAM was the only component of the AIS complex found to be affected in mutant Purkinje cells (Figure 1A), Selleckchem LY2157299 and the number of Purkinje cells positive for NrCAM was reduced from 93.0% ± 1.3% to 7.4% ± 0.1% (mean values ± SEM, n = 3,

40 cells per animal, p < 0.0001, unpaired Student's t test). In order to establish if the presence of NrCAM at the AIS was dependent on the neuronal isoform of Neurofascin, Nfasc186, we generated transgenic mice expressing FLAG-tagged Nfasc186 on a Neurofascin null background. The transgenic Nfasc186 was targeted appropriately and rescued NrCAM at the AIS (Figure 1B). Interestingly, although the stable targeting of NrCAM to the AIS was dependent on Nfasc186, the converse Idoxuridine was not true (see Figure S1 available online); neither was NrCAM required for the long-term stability of the AIS (Figure S1). We concluded that although Nfasc186 is not required for in vivo assembly of voltage-gated sodium channels at the AIS, it recruits NrCAM to the AIS complex. Since the Neurofascins are not required for the clustering of sodium channels or the majority of their associated proteins in the AIS complex,

we asked if instead they have a role in maintaining the complex. Since Neurofascin null mice die at P7 (Sherman et al., 2005), it is not possible to study the long-term stability of their initial segments in vivo. Hence, we first examined organotypic slice cultures derived from Neurofascin null cerebella. Such cultures are known to maintain viability for months (Kessler et al., 2008). In the absence of the Neurofascins clustering of components of the AIS was complete after 9 days in vitro (DIV). The exception was NrCAM, as found in vivo (Figures 1A and 2). Further culture for up to 15 days resulted in the dispersal of sodium channels, AnkyrinG and βIV-Spectrin, whereas the wild-type AIS remained intact (Figure 2). This suggests that the Neurofascins are required for AIS stability, at least in vitro.

As shown previously with VSDI for electrical events, we now demon

As shown previously with VSDI for electrical events, we now demonstrate that Ca2+ waves propagate continuously through the cortex, recruiting large areas, perhaps even the entire cortex. In contrast to studies applying VSDI (Huang et al., 2010), we did not observe spiral or other nonlinear wave patterns. A possible explanation for this discrepancy may be that VSDI reflects primarily subthreshold activity, whereas Ca2+ imaging using fluorescent dyes mainly reflects suprathreshold neuronal activity (Garaschuk et al.,

2006b; Lütcke et al., 2010; Rochefort et al., 2009). The first field potential recordings of thalamic slow-wave oscillations were obtained in hemidecorticated cats in vivo (Timofeev and Steriade, 1996). In that study, the authors provided evidence from a small sample of combined cortical EEG and thalamic

learn more field potential recordings that spontaneous cortical waves preceded the associated thalamic ones. In the present study, we determined the corticothalamic wave latencies only for sensory- and optogenetically evoked waves, because these have, unlike spontaneous waves, a defined, unique site of cortical initiation. For such evoked waves, we demonstrate a clear temporal dominance of cortical over the thalamic wave initiation. Thus, visually evoked Ca2+ waves as well as Ca2+ waves evoked by intrathalamic optogenetic stimulation occur first in the DAPT visual cortex and only after a delay of about 180–200 ms in the dLGN. We emphasize that our findings only apply to the slow-wave activity. The primary fast neuronal activation upon visual stimulation will take place in the visual thalamic nuclei first, before being transmitted to the thalamorecipient cortical layer 4. Irrespective of their mode of initiation, Ca2+ waves were found to be remarkably unitary with virtually constant amplitudes and durations at a given brain location. This suggests that during waves of different origins, including the spontaneous, sensory-evoked, or optogenetically induced ones, a similar number of neurons participates on average in the slow oscillatory activity.

Our results obtained using optical Ca2+ recordings reveal Isotretinoin properties of the slow oscillatory events that were not recognized previously. First, we observed an all-or-none behavior of the Ca2+ waves. The analysis of the optogenetically evoked waves particularly demonstrated that light pulses as short as 3 ms either evoke a full wave or no wave at all. Similarly, different light intensities for a given duration of the stimulating light pulse either evoked a full wave or no wave at all. Second, repetitive stimulation allowed the induction of consecutive waves only for intervals that were longer than about 2.5 s. For shorter intervals, wave initiation was either partially or, for very short intervals, completely refractory.

The characteristics of responding LC neurons and their direct rel

The characteristics of responding LC neurons and their direct relation to autonomic responses as outlined above indict the LC as an intricate, primary, and necessary component of the orienting reflex. An example of an orienting response of an LC neuron can be seen in Figure 2. Single unit recordings

of LC were made during differential conditioning of two odors using a go/no go protocol with reward associated with the target odor. The protocol included a preparatory stimulus, a Abiraterone mouse light that preceded the presentation of the odor by 2 s. LC neurons showed a consistent response to the light during the learning session, with no habituation. LC cells stopped responding to the light during extinction; responses to this preparatory stimulus were reinstated as soon as the reward was reinstated in the protocol

(from Bouret and Sara, 2004). In sum, converging evidence indicates that LC neurons are activated by situations that elicit a behavioral orienting response, when the check details animal interrupts its ongoing activity to face the orienting stimulus. This is in conjunction with autonomic activation mobilizing resources to organize adaptive behavior. Given its widespread influence on forebrain structures, the LC, driven by its major afferent, the NGC, could mediate Kupalov’s proposed “Truncated Conditioned Reflex,” inducing cortical arousal and resetting network activity in the forebrain. There are both excitatory and inhibitory influences on LC from direct monosynaptic projections from prefrontal cortex (Sara and Hervé-Minvielle, 1995; Jodo et al., 1998). When the two regions are firing

in an oscillatory mode, we observed what appeared to be a phasic opposition (Figure 3A) (Sara and Hervé-Minvielle, 1995, Lestienne et al., 1997; Shinba et al., 2000). We recently examined with more precision the phasic relation of LC activity to cortical slow Linifanib (ABT-869) oscillations in nonanesthetized rats and found that about 50% of LC cells were time locked and phase locked to the oscillation, firing about 60 ms after the trough of the down state, during the transition from “down” to “up” state, with no phase overlap between the two populations of neurons (Figure 3B; see also Eschenko et al., 2012). The fact that LC activity is so closely related to spontaneous fluctuations of cortical excitability implies a functional prefrontal-coerulear interaction during slow oscillations. The temporal order of firing of LC and PFC neurons, together with the evidence for LC firing on the ascending edge of the EEG slow wave, suggests that LC may well be involved in promoting or facilitating down-to-up state transitions. While these results do not unequivocally resolve the question of who drives whom, they are compatible with the idea that the LC and the PFC have a mutual excitatory influence. In other words, firing in frontal neurons “wakes up” the LC, and this in turn facilitates the cortical transition to the fully depolarized “up” state.