The effect of older age on outcomes of rTMS treatment for treatment-resistant depression.

Clinical outcomes of repetitive transcranial magnetic stimulation (rTMS) for treatment of treatment-resistant depression (TRD) vary widely and there is no mood rating scale that is standard for assessing rTMS outcome. It remains unclear whether TMS is as efficacious in older adults with late-life depression (LLD) compared to younger adults with major depressive disorder (MDD). This study examined the effect of age on outcomes of rTMS treatment of adults with TRD. Self-report and observer mood ratings were measured weekly in 687 subjects ages 16-100 years undergoing rTMS treatment using the Inventory of Depressive Symptomatology 30-item Self-Report (IDS-SR), Patient Health Questionnaire 9-item (PHQ), Profile of Mood States 30-item, and Hamilton Depression Rating Scale 17-item (HDRS). All rating scales detected significant improvement with treatment; response and remission rates varied by scale but not by age (response/remission ≥ 60: 38%-57%/25%-33%; <60: 32%-49%/18%-25%). Proportional hazards models showed early improvement predicted later improvement across ages, though early improvements in PHQ and HDRS were more predictive of remission in those < 60 years (relative to those ≥ 60) and greater baseline IDS burden was more predictive of non-remission in those ≥ 60 years (relative to those < 60). These results indicate there is no significant effect of age on treatment outcomes in rTMS for TRD, though rating instruments may differ in assessment of symptom burden between younger and older adults during treatment.

Repetitive transcranial magnetic stimulation treatment of major depressive disorder and comorbid chronic pain: response rates and neurophysiologic biomarkers.

BACKGROUND: Major depressive disorder (MDD) and chronic pain are highly comorbid, and pain symptoms are associated with a poorer response to antidepressant medication treatment. It is unclear whether comorbid pain also is associated with a poorer response to treatment with repetitive transcranial magnetic stimulation (rTMS). METHODS: 162 MDD subjects received 30 sessions of 10 Hz rTMS treatment administered to the left dorsolateral prefrontal cortex (DLPFC) with depression and pain symptoms measured before and after treatment. For a subset of 96 patients, a resting-state electroencephalogram (EEG) was recorded at baseline. Clinical outcome was compared between subjects with and without comorbid pain, and the relationships among outcome, pain severity, individual peak alpha frequency (PAF), and PAF phase-coherence in the EEG were examined. RESULTS: 64.8% of all subjects reported pain, and both depressive and pain symptoms were significantly reduced after rTMS treatment, irrespective of age or gender. Patients with severe pain were 27% less likely to respond to MDD treatment than pain-free individuals. PAF was positively associated with pain severity. PAF phase-coherence in the somatosensory and default mode networks was significantly lower for MDD subjects with pain who failed to respond to MDD treatment. CONCLUSIONS: Pain symptoms improved after rTMS to left DLPFC in MDD irrespective of age or gender, although the presence of chronic pain symptoms reduced the likelihood of treatment response. Individual PAF and baseline phase-coherence in the sensorimotor and midline regions may represent predictors of rTMS treatment outcome in comorbid pain and MDD.

Bilateral Cerebellar Repetitive Transcranial Magnetic Stimulation for Chronic Ataxia After Hemorrhagic Stroke: a Case Report.

There are insufficient treatment options available for recovery related to cerebellar ataxia. Limited data using repetitive transcranial magnetic stimulation (rTMS) have demonstrated reduction of symptom burden, though associated with nonuniform cerebellar ataxia etiologies and differing rTMS treatment protocols. Additionally, there are limited available data for use of rTMS in individuals suffering from stroke-related symptoms. We present the case of a patient with chronic cerebellar ataxia following a hemorrhagic stroke who underwent inhibitory rTMS to bilateral cerebellar targets with demonstrated improvement in symptoms.

Psychostimulant use and clinical outcome of repetitive transcranial magnetic stimulation treatment of major depressive disorder.

BACKGROUND: Repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for major depressive disorder (MDD). Psychostimulant medication use may be associated with improved rTMS outcomes, but a detailed understanding of these relationships is lacking. METHODS: We compared MDD subjects taking psychostimulants (n = 37) with those not taking one of these medications (n = 53) during a course of 30 rTMS treatments. Changes in the 30-item Inventory of Depressive Symptomatology Self Report (IDS-SR30) subscale scores were examined at treatment 30. We also subdivided subjects into three categories based on drug mechanism and looked at IDS-SR30 total score after treatments 10, 20, and 30. RESULTS: Subjects taking psychostimulants had a significantly greater overall clinical improvement than those not taking these medications at treatment 30. The psychostimulant group also improved significantly more than the control group in "sleep" and "mood/cognition," but not "anxiety/arousal" IDS-SR30 subscales. No differences were detected among individual drug categories, which may reflect the limited sample size for individual medications. There was a negative dose-response relationship for the lisdexamfetamine/dextroamphetamine group, in which lower doses were associated with better clinical outcome. CONCLUSIONS: Psychostimulant medications may enhance clinical efficacy of rTMS for MDD by preferentially impacting specific symptom domains. For some psychostimulants, these effects may be dose-dependent. Prospective clinical trials are needed to guide psychostimulant augmentation of brain stimulation therapies.

Absence of early mood improvement as a robust predictor of rTMS nonresponse in major depressive disorder.

BACKGROUND: Symptoms of major depressive disorder (MDD) are reported to change early in treatment with repetitive transcranial magnetic stimulation (rTMS). We evaluated early changes in sleep, anxiety, and mood as predictors of nonresponse to rTMS treatment. METHODS: Three hundred twenty-nine subjects with nonpsychotic MDD completed a 6-week course of rTMS treatment. Subjects were stratified by the severity of their baseline depression, and had their overall depressive symptoms recorded every week of treatment. We evaluated lack of improvement in sleep, anxiety, and mood symptoms after 1 and 2 weeks as potential predictors of eventual nonresponse, defined as <50% improvement in compositive depressive symptoms after 6 weeks. This was measured as negative predictive value (NPV; the likelihood that lack of early symptom improvement accurately predicted eventual treatment nonresponse). RESULTS: Subjects with severe or very severe baseline depression achieving <20% improvement in mood at 1 week were correctly predicted as nonresponders with NPVs largely >90%. At 2 weeks, subjects with very severe baseline depression who failed to demonstrate any improvement in mood were all nonresponders. Lack of improvement in sleep at 2 weeks was also a significant predictor. CONCLUSIONS: Identifying a lack of early mood improvement is a practical and robust method to predict rTMS nonresponse. This suggests a treatment protocol change may be indicated in patients with more severe baseline depression showing minimal early mood improvement.

Deconstructing complexity: serial block-face electron microscopic analysis of the hippocampal mossy fiber synapse.

The hippocampal mossy fiber (MF) terminal is among the largest and most complex synaptic structures in the brain. Our understanding of the development of this morphologically elaborate structure has been limited because of the inability of standard electron microscopy techniques to quickly and accurately reconstruct large volumes of neuropil. Here we use serial block-face electron microscopy (SBEM) to surmount these limitations and investigate the establishment of MF connectivity during mouse postnatal development. Based on volume reconstructions, we find that MF axons initially form bouton-like specializations directly onto dendritic shafts, that dendritic protrusions primarily arise independently of bouton contact sites, and that a dramatic increase in presynaptic and postsynaptic complexity follows the association of MF boutons with CA3 dendritic protrusions. We also identify a transient period of MF bouton filopodial exploration, followed by refinement of sites of synaptic connectivity. These observations enhance our understanding of the development of this highly specialized synapse and illustrate the power of SBEM to resolve details of developing microcircuits at a level not easily attainable with conventional approaches.

Transformations in prefrontal ensemble activity underlying rapid threat avoidance learning.

The capacity to learn cues that predict aversive outcomes, and understand how to avoid those outcomes, is critical for adaptive behavior. Naturalistic avoidance often means accessing a safe location, but whether a location is safe depends on the nature of the impending threat. These relationships must be rapidly learned if animals are to survive. The prelimbic subregion (PL) of the medial prefrontal cortex (mPFC) integrates learned associations to influence these threat avoidance strategies. Prior work has focused on the role of PL activity in avoidance behaviors that are fully established, leaving the prefrontal mechanisms that drive rapid avoidance learning poorly understood. To determine when and how these learning-related changes emerge, we recorded PL neural activity using miniscope calcium imaging as mice rapidly learned to avoid a threatening cue by accessing a safe location. Over the course of learning, we observed enhanced modulation of PL activity representing intersections of a threatening cue with safe or risky locations and movements between them. We observed rapid changes in PL population dynamics that preceded changes observable in the encoding of individual neurons. Successful avoidance could be predicted from cue-related population dynamics during early learning. Population dynamics during specific epochs of the conditioned tone period correlated with the modeled learning rates of individual animals. In contrast, changes in single-neuron encoding occurred later, once an avoidance strategy had stabilized. Together, our findings reveal the sequence of PL changes that characterize rapid threat avoidance learning.

Safety and efficacy of targeting the supplementary motor area with double-cone deep transcranial magnetic stimulation vs figure-eight coil in treatment of obsessive-compulsive disorder with comorbid major depressive disorder.

BACKGROUND AND OBJECTIVE: The Supplementary Motor Area (SMA), a relatively large brain structure predominantly located along the interhemispheric fissure, is an established target for repetitive Transcranial Magnetic Stimulation (rTMS) treatment of Obsessive-Compulsive Disorder (OCD). We investigated the feasibility, safety, and efficacy of targeting SMA using a double-cone "deep" TMS coil compared to conventional figure-eight coil for treatment of OCD with comorbid Major Depressive Disorder (MDD). METHODS: Sixty-two patients with treatment-resistant OCD and comorbid MDD participated in the study. All patients received high-frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC) with a figure-eight coil (MagVenture B70), followed by 1 Hz rTMS over the bilateral SMA using either the B70 (N = 25) or double-cone deep coil (MagVenture DB80) (n = 23) for 36 treatment sessions. Weekly clinical assessments were conducted. RESULTS: Subjects overall had significant reductions in OCD and depressive symptom severity at the primary endpoint. Subjects stimulated at SMA with the double-cone deep coil had statistically significantly lesser reductions in overall OCD and depression symptom severity compared to the figure-eight group. The intensity of stimulation at SMA was significantly greater with the double-cone deep than figure-eight coil and e-field modeling showed that it affected broader regions beyond SMA (off-target stimulation). There was no significant difference in reported tolerability between groups. CONCLUSIONS: SMA stimulation using either a double-cone deep or conventional figure-of-eight coil was safe and was associated with a significant reduction in comorbid OCD and depression symptoms, but the higher intensities of stimulation with the double-cone deep coil used in this study were significantly less clinically beneficial than figure-eight coil stimulation.

The role of sex and age in the differential efficacy of 10 Hz and intermittent theta-burst (iTBS) repetitive transcranial magnetic stimulation (rTMS) treatment of major depressive disorder (MDD).

BACKGROUND: Sex- and age-dependent outcome differences have been observed in treatment of Major Depressive Disorder (MDD), including 10 Hz repetitive Transcranial Magnetic Stimulation (rTMS). We examined whether there are sex- and age-dependent differences in outcome with intermittent Theta Burst Stimulation (iTBS), another rTMS protocol. METHODS: The relationship between biological sex, age, and treatment outcome was retrospectively examined among 414 patients with MDD treated with 10 Hz or iTBS rTMS. Linear mixed-effects modeling was used to examine the association between treatment and change in the 30-item Inventory of Depressive Symptomatology Self-Report (IDS-SR30) score from baseline to treatments 10 and 30, with biological sex (M/F), protocol (iTBS/10 Hz), age (≥/<50 years old), and time (treatment 1/10/30) included as fixed effects. The three-way sex-protocol-time and age-protocol-time interactions were used to determine any differential relationships between protocol and outcome dependent on sex and age. Post-hoc t-tests were conducted to examine differences in improvement. RESULTS: There was a significant three-way sex-protocol-time interaction at treatments 10 (p = 0.016) and 30 (p = 0.031). Males showed significantly greater improvement with iTBS than females at treatments 10 (p = 0.041) and 30 (p = 0.035), while females showed numerically greater improvement with 10 Hz treatment. While there was not a significant three-way age-protocol-time interaction, there was a significant interaction between age (≥50 years old) and time at treatments 10 (p = 0.007) and 30 (p = 0.042), and among age, sex, and time at treatment 30 (p = 0.028). LIMITATIONS: Retrospective naturalistic treatment protocol. CONCLUSIONS: iTBS appeared less efficacious in females than in males, and rTMS overall was more efficacious in patients over fifty, particularly females.

Pretreatment pupillary reactivity is associated with differential early response to 10 Hz and intermittent theta-burst repetitive transcranial magnetic stimulation (rTMS) treatment of major depressive disorder (MDD).

BACKGROUND: Repetitive Transcranial Magnetic Stimulation (rTMS) is an effective treatment for Major Depressive Disorder (MDD). Two common rTMS protocols, 10 Hz and intermittent theta burst stimulation (iTBS), have comparable rates of efficacy in groups of patients. Recent evidence suggests that some individuals may be more likely to benefit from one form of stimulation than the other. The pretreatment pupillary light reflex (PLR) is significantly associated with response to a full course of rTMS using heterogeneous stimulation protocols. OBJECTIVE: To test whether the relationship between pretreatment PLR and early symptom improvement differed between subjects treated with iTBS or 10 Hz stimulation. METHODS: PLR was measured in 52 subjects who received solely 10 Hz (n = 35) or iTBS (n = 17) to left dorsolateral prefrontal cortex (DLPFC) for the first ten sessions of their treatment course. Primary outcome measure was the percent change of Inventory of Depressive Symptomatology - Self Report (IDS-SR) from session 1 to session 10. RESULTS: There was a positive association between normalized maximum constriction velocity (nMCV) and early improvement in subjects receiving 10 Hz stimulation (R = 0.48, p = 0.004) and a negative association in subjects receiving iTBS (R = -0.52, p = 0.03). ANOVA revealed a significant interaction between nMCV and the type of initial stimulation (p = 0.001). Among subjects with low nMCV, those initially treated with iTBS showed 2.6 times greater improvement after 10 sessions (p = 0.01) than subjects initially receiving 10 Hz stimulation. CONCLUSION: nMCV may detect physiologic differences between those likely to benefit from 10 Hz or iTBS treatment. Future studies should examine whether PLR could guide prospective treatment selection.

A comparison of self- and observer-rated scales for detecting clinical improvement during repetitive transcranial stimulation (rTMS) treatment of depression.

Clinical outcomes of repetitive Transcranial Magnetic Stimulation (rTMS) for treatment of Major Depressive Disorder (MDD) vary widely, and no single mood rating scale is standard for assessing rTMS outcomes. This study of 708 subjects undergoing clinical rTMS compared the performance of four scales in measuring symptom change during rTMS treatment. Self-report and observer ratings were examined weekly with the Inventory of Depressive Symptomatology 30-item (IDS), Patient Health Questionnaire 9-item (PHQ), Profile of Mood States 30-item (POMS), and Hamilton Depression Rating Scale 17-item (HDRS). While all scales were correlated and detected significant improvement, the degree of improvement over time as well as response (33-50%) and remission (20-24%) rates varied significantly. Higher baseline severity was associated with lower likelihood of remission, and greater improvement by sessions 5 and 10 predicted response across all scales. Use of only a single scale to assess outcome conferred 14-36% risk of failing to detect response/remission indicated by another scale. The PHQ was most likely to indicate improvement and least likely to miss response or remission. These findings indicate that assessment of symptom burden during rTMS treatment may be most accurately assessed through use of multiple instruments.

Convergence of Clinically Relevant Manipulations on Dopamine-Regulated Prefrontal Activity Underlying Stress Coping Responses.

BACKGROUND: Depression is pleiotropic and influenced by diverse genetic, environmental, and pharmacological factors. Identifying patterns of circuit activity on which many of these factors converge would be important, because studying these patterns could reveal underlying pathophysiological processes and/or novel therapies. Depression is commonly assumed to involve changes within prefrontal circuits, and dopamine D2 receptor (D2R) agonists are increasingly used as adjunctive antidepressants. Nevertheless, how D2Rs influence disease-relevant patterns of prefrontal circuit activity remains unknown. METHODS: We used brain slice calcium imaging to measure how patterns of prefrontal activity are modulated by D2Rs, antidepressants, and manipulations that increase depression susceptibility. To validate the idea that prefrontal D2Rs might contribute to antidepressant responses, we used optogenetic and genetic manipulations to test how dopamine, D2Rs, and D2R+ neurons contribute to stress-coping behavior. RESULTS: Patterns of positively correlated activity in prefrontal microcircuits are specifically enhanced by D2R stimulation as well as by two mechanistically distinct antidepressants, ketamine and fluoxetine. Conversely, this D2R-driven effect was disrupted in two etiologically distinct depression models, a genetic susceptibility model and mice that are susceptible to chronic social defeat. Phasic stimulation of dopaminergic afferents to the prefrontal cortex and closed-loop stimulation of D2R+ neurons increased effortful responses to tail suspension stress, whereas prefrontal D2R deletion reduced the duration of individual struggling episodes. CONCLUSIONS: Correlated prefrontal microcircuit activity represents a point of convergence for multiple depression-related manipulations. Prefrontal D2Rs enhance this activity. Through this mechanism, prefrontal D2Rs may promote network states associated with antidepressant actions and effortful responses to stress.

BehaviorDEPOT is a simple, flexible tool for automated behavioral detection based on markerless pose tracking.

Quantitative descriptions of animal behavior are essential to study the neural substrates of cognitive and emotional processes. Analyses of naturalistic behaviors are often performed by hand or with expensive, inflexible commercial software. Recently, machine learning methods for markerless pose estimation enabled automated tracking of freely moving animals, including in labs with limited coding expertise. However, classifying specific behaviors based on pose data requires additional computational analyses and remains a significant challenge for many groups. We developed BehaviorDEPOT (DEcoding behavior based on POsitional Tracking), a simple, flexible software program that can detect behavior from video timeseries and can analyze the results of experimental assays. BehaviorDEPOT calculates kinematic and postural statistics from keypoint tracking data and creates heuristics that reliably detect behaviors. It requires no programming experience and is applicable to a wide range of behaviors and experimental designs. We provide several hard-coded heuristics. Our freezing detection heuristic achieves above 90% accuracy in videos of mice and rats, including those wearing tethered head-mounts. BehaviorDEPOT also helps researchers develop their own heuristics and incorporate them into the software's graphical interface. Behavioral data is stored framewise for easy alignment with neural data. We demonstrate the immediate utility and flexibility of BehaviorDEPOT using popular assays including fear conditioning, decision-making in a T-maze, open field, elevated plus maze, and novel object exploration.

Use of right orbitofrontal repetitive transcranial magnetic stimulation (rTMS) augmentation for treatment-refractory obsessive-compulsive disorder with comorbid major depressive disorder.

We examined the safety and efficacy of repetitive Transcranial Magnetic Stimulation (rTMS) of the right orbitofrontal cortex (OFC) in patients with refractory obsessive-compulsive disorder (OCD) and comorbid Major Depressive Disorder. All participants (n = 26) received excitatory stimulation of the left dorsolateral prefrontal cortex followed by inhibitory stimulation of bilateral supplementary motor area for 10 sessions. In 18 patients with poor early OCD response, treatment was augmented with OFC inhibitory stimulation after the tenth treatment session. Augmentation with OFC stimulation was well-tolerated, and associated with further alleviation of both OCD and depression symptoms, particularly in individuals with more severe illnesses.

Sequential Prefrontal and Temporoparietal Repetitive Transcranial Magnetic Stimulation (rTMS) for Treatment of Tinnitus With and Without Comorbid Depression: A Case Series and Systematic Review.

Background: Tinnitus distress is related to both the loudness and intrusiveness of the tinnitus percept. Treatment approaches targeting both attentional/limbic and auditory systems may better alleviate tinnitus distress than approaches targeting the auditory system alone. Materials and Methods: Ten subjects with chronic tinnitus received sequential rTMS treatment involving: 1) excitatory stimulation administered to the left dorsolateral prefrontal cortex (DLPFC) or inhibitory stimulation administered to the right DLPFC, followed by 2) inhibitory stimulation administered to primary auditory cortex (Heschel's gyrus or HG). A systematic literature review was performed to evaluate the existing literature on sequential repetitive Transcranial Magnetic Stimulation (rTMS) treatment approaches for tinnitus. Results of the case series are interpreted in the context of tinnitus neurobiology and the extant literature. Results: Subjects experienced a significant decrease (average 21.7%) in symptoms on the Tinnitus Functional Index (TFI). Those with tinnitus alone experienced a greater mean symptom reduction than those with comorbid MDD (27.7 vs. 17.0%, respectively). Adverse effects were transient and minor. Literature review confirmed that sequential approaches had some advantages compared to single site rTMS; in general, the addition of 1 Hz treatment at DLPFC was superior to single site rTMS in the short term (1-12 weeks), while the addition of 20 Hz treatment at DLPFC appeared superior in the long term (90-180 days). Conclusions: Sequential rTMS approaches for the treatment of tinnitus-particularly those administering low-frequency treatment at left DLPFC-merit further investigation.

Treatment of Spider Phobia Using Repeated Exposures and Adjunctive Repetitive Transcranial Magnetic Stimulation: A Proof-of-Concept Study.

Background: Specific phobias represent the largest category of anxiety disorders. Previous work demonstrated that stimulating the ventromedial prefrontal cortex (vmPFC) with repetitive Transcranial Magnetic Stimulation (rTMS) may improve response to exposure therapy for acrophobia. Objective: To examine feasibility of accelerating extinction learning in subjects with spider phobia using intermittent Theta Burst Stimulation (iTBS) rTMS of vmPFC. Methods: In total, 17 subjects with spider phobia determined by spider phobia questionnaires [Spider Phobia Questionnaire (SPQ) and Fear of Spiders questionnaire (FSQ)] underwent ratings of fear of spiders as well as behavioral and skin conductance data during a behavioral avoidance test (BAT). Subjects then received a sequential protocol of in vivo spider exposure followed by iTBS for three sessions administered to either active or control treatment sites (vmPFC [n = 8] or vertex [n = 9], respectively), followed 1 week later by repetition of questionnaires and BAT. Results: All subjects improved significantly regardless of group across both questionnaires (FSQ η2 = 0.43, p = 0.004; SPQ η2 = 0.39, p = 0.008) and skin conductance levels during BAT (Wald χ2 = 30.9, p < 0.001). Subjects in the vmPFC group tolerated lower treatment intensity than in the control group, and there was a significant correlation between treatment intensity, BAT subjective distress improvement, and physiologic measures (all ρ > 0.5). Conclusion: This proof-of-concept study provides preliminary evidence that a sequential exposure and iTBS over vmPFC is feasible and may have rTMS intensity-dependent effects on treatment outcomes, providing evidence for future areas of study in the use of rTMS for phobias.

Subthreshold stimulation intensity is associated with greater clinical efficacy of intermittent theta-burst stimulation priming for Major Depressive Disorder.

BACKGROUND: Intermittent theta-burst stimulation priming (iTBS-P) can improve clinical outcome of patients with Major Depressive Disorder (MDD) who do not show early benefit from 10 Hz stimulation of left dorsolateral prefrontal cortex (DLPFC), also known as high-frequency left-sided (HFL) stimulation. The intensity and pulse number for iTBS-P needed to induce clinical benefit have not been systematically examined. OBJECTIVE: To study the effect of intensity and pulse number on the clinical efficacy of iTBS-P. METHODS: We conducted a retrospective review of 71 participants who received at least five sessions of HFL with limited clinical benefit and received iTBS-P augmentation for between 5 and 25 sessions. Intensity of iTBS-P priming stimuli ranged from 75 to 120% of motor threshold (MT) and pulse number ranged from 600 to 1800. Associations among intensity, pulse number, and clinical outcome were analyzed using a mixed methods linear model with change in IDS-SR as the primary outcome variable, priming stimulation intensity (subthreshold or suprathreshold), pulse number (<1200 or >1200 pulses), and gender as fixed factors, and number of iTBS-P treatments and age as continuous covariates. RESULTS: Subjects who received subthreshold intensity iTBS-P experienced greater reduction in depressive symptoms than those who received suprathreshold iTBS-P (p = 0.011) with no effect of pulse number after controlling for stimulus intensity. CONCLUSIONS: Subthreshold intensity iTBS-P was associated with greater clinical improvement than suprathreshold stimulation. This finding is consistent with iTBS-P acting through homeostatic plasticity mechanisms.

Krüppel-like factor 9 is necessary for late-phase neuronal maturation in the developing dentate gyrus and during adult hippocampal neurogenesis.

The dentate gyrus (DG) is modified throughout life by integration of new adult-born neurons. Similarities in neuronal maturation during DG development and adult hippocampal neurogenesis suggest that genetically encoded intrinsic regulatory mechanisms underlying these temporally distinct processes are conserved and reused. Here, we identify a novel transcriptional regulator of dentate granule neuron maturation, Krüppel-like factor 9 (Klf-9). We show that Klf-9 expression is induced by neuronal activity and as dentate granule neurons functionally integrate in the developing and adult DG. During development, dentate granule neurons lacking Klf-9 show delayed maturation as reflected by altered expression of early-phase markers, dendritic spine formation, and electrophysiological properties. Adult Klf-9-null mice exhibit normal stem cell proliferation and cell fate specification in the DG but show impaired differentiation of adult-born neurons and decreased neurogenesis-dependent synaptic plasticity. Behavioral analysis of Klf-9-null mice revealed a subtle increase in anxiety-like behavior and an impairment in contextual fear discrimination learning. Thus, Klf-9 is necessary for late-phase maturation of dentate granule neurons both in DG development and during adult hippocampal neurogenesis. Klf-9-dependent neuronal maturation may therefore represent a candidate regulatory mechanism underlying these temporally distinct processes.

Strategies for augmentation of high-frequency left-sided repetitive transcranial magnetic stimulation treatment of major depressive disorder.

BACKGROUND: Repetitive Transcranial Magnetic Stimulation (rTMS) is an effective intervention for treatment-resistant Major Depressive Disorder (MDD). Early improvement during high-frequency left-sided (HFL) stimulation of the dorsolateral prefrontal cortex (DLPFC) is an important predictor of longer-term outcome, but most patients benefit later in their treatment course. We examined patients without early improvement with HFL to determine whether augmentation with additional stimulation approaches improved treatment outcome. METHODS: 139 participants received HFL in a measurement-based care paradigm. Participants who achieved < 20% improvement by treatment 10 could continue with HFL (N = 17) or receive one of two augmentation strategies: bilateral stimulation (BL; HFL followed by low-frequency stimulation of right DLPFC) (N = 69) or intermittent theta-burst priming of left DLPFC (iTBS-P) (N = 17) for their remaining treatment sessions. The primary outcome was the percent reduction in depressive symptoms at treatment 30. RESULTS: Participants who achieved < 20% improvement by treatment 10 and continued with HFL showed limited benefit. iTBS-P participants had significantly greater improvement, while those receiving BL trended toward improved outcomes. Ten sessions of either augmentation strategy appeared necessary to determine the likelihood of benefit. CONCLUSIONS: Augmentation of early non-response to HFL appears to improve rTMS outcomes, with a novel iTBS-P strategy surpassing both continued HFL or BL treatment in participants with < 20% improvement after 10 treatments. These findings suggest that measurement-based care with addition of augmented stimulation for those not showing early improvement may yield superior rTMS treatment outcomes.

VIP Interneurons Contribute to Avoidance Behavior by Regulating Information Flow across Hippocampal-Prefrontal Networks.

Inhibitory interneurons expressing vasoactive intestinal polypeptide (VIP) are known to disinhibit cortical neurons. However, it is unclear how disinhibition, occurring at the single-cell level, interacts with network-level patterns of activity to shape complex behaviors. To address this, we examined the role of prefrontal VIP interneurons in a widely studied mouse behavior: deciding whether to explore or avoid the open arms of an elevated plus maze. VIP interneuron activity increases in the open arms and disinhibits prefrontal responses to hippocampal inputs, which are known to transmit signals related to open arm avoidance. Indeed, inhibiting VIP interneurons disrupts network-level representations of the open arms and decreases open arm avoidance specifically when hippocampal-prefrontal theta synchrony is strong. Thus, VIP interneurons effectively gate the ability of hippocampal input to generate prefrontal representations, which drive avoidance behavior. This shows how VIP interneurons enable cortical circuits to integrate specific inputs into network-level representations that guide complex behaviors. VIDEO ABSTRACT.