Aligning evidence for the genesis of visual gamma oscillations.

New findings in PLOS Biology show that visual gamma oscillations are greatly attenuated by small spatial discontinuities in visual stimuli, suggesting that their genesis occurs in response to predictable regularities in the visual world.

Default mode network electrophysiological dynamics and causal role in creative thinking.

The default mode network (DMN) is a widely distributed, intrinsic brain network thought to play a crucial role in internally-directed cognition. The present study employs stereo-electroencephalography in 13 human patients, obtaining high resolution neural recordings across multiple canonical DMN regions during two processes that have been associated with creative thinking: spontaneous and divergent thought. We probe these two DMN-associated higher cognitive functions through mind wandering and alternate uses tasks, respectively. Our results reveal DMN recruitment during both tasks, as well as a task-specific dissociation in spatiotemporal response dynamics. When compared to the fronto-parietal network, DMN activity was characterized by a stronger increase in gamma band power (30-70 Hz) coupled with lower theta band power (4-8 Hz). The difference in activity between the two networks was especially strong during the mind wandering task. Within the DMN, we found that the tasks showed different dynamics, with the alternate uses task engaging the DMN more during the initial stage of the task, and mind wandering in the later stage. Gamma power changes were mainly driven by lateral DMN sites, while theta power displayed task-specific effects. During alternate uses task, theta changes did not show spatial differences within the DMN, while mind wandering was associated to an early lateral and late dorsomedial DMN engagement. Furthermore, causal manipulations of DMN regions using direct cortical stimulation preferentially decreased the originality of responses in the alternative uses task, without affecting fluency or mind wandering. Our results suggest that DMN activity is flexibly modulated as a function of specific cognitive processes and supports its causal role in divergent thinking. These findings shed light on the neural constructs supporting different forms of cognition and provide causal evidence for the role of DMN in the generation of original connections among concepts.

Biased Orientation and Color Tuning of the Human Visual Gamma Rhythm.

Narrowband γ oscillations (NBG: ∼20-60 Hz) in visual cortex reflect rhythmic fluctuations in population activity generated by underlying circuits tuned for stimulus location, orientation, and color. A variety of theories posit a specific role for NBG in encoding and communicating this information within visual cortex. However, recent findings suggest a more nuanced role for NBG, given its dependence on certain stimulus feature configurations, such as coherent-oriented edges and specific hues. Motivated by these factors, we sought to quantify the independent and joint tuning properties of NBG to oriented and color stimuli using intracranial recordings from the human visual cortex (male and female). NBG was shown to display a cardinal orientation bias (horizontal) and also an end- and mid-spectral color bias (red/blue and green). When jointly probed, the cardinal bias for orientation was attenuated and an end-spectral preference for red and blue predominated. This loss of mid-spectral tuning occurred even for recording sites showing large responses to uniform green stimuli. Our results demonstrate the close, yet complex, link between the population dynamics driving NBG oscillations and known feature selectivity biases for orientation and color within visual cortex. Such a bias in stimulus tuning imposes new constraints on the functional significance of the visual γ rhythm. More generally, these biases in population electrophysiology will need to be considered in experiments using orientation or color features to examine the role of visual cortex in other domains, such as working memory and decision-making.SIGNIFICANCE STATEMENT Oscillations in electrophysiological activity occur in visual cortex in response to stimuli that strongly drive the orientation or color selectivity of visual neurons. The significance of this induced "γ rhythm" to brain function remains unclear. Answering this question requires understanding how and why some stimuli can reliably generate oscillatory γ activity while others do not. We examined how different orientations and colors independently and jointly modulate γ oscillations in the human brain. Our data show that γ oscillations are greatest for certain orientations and colors that reflect known response biases in visual cortex. Such findings complicate the functional significance of γ oscillations but open new avenues for linking circuits to population dynamics in visual cortex.

Social Functioning in Individuals Affected by Childhood Maltreatment: Establishing a Research Agenda to Inform Interventions.

Childhood maltreatment (CM) is linked to impairments in various domains of social functioning. Here, we argue that it is critical to identify factors that underlie impaired social functioning as well as processes that mediate the beneficial health effects of positive relationships in individuals exposed to CM. Key research recommendations are presented, focusing on: (1) identifying attachment-related alterations in specific inter- and intrapersonal processes (e.g., regulation of closeness and distance) that underlie problems in broader domains of social functioning (e.g., lack of perceived social support) in individuals affected by CM; (2) identifying internal (e.g., current emotional state) and external situational factors (e.g., cultural factors, presence of close others) that modulate alterations in specific social processes; and (3) identifying mechanisms that explain the positive health effects of intact social functioning. Methodological recommendations include: (1) assessing social processes through interactive and (close to) real-life assessments inside and outside the laboratory; (2) adopting an interdisciplinary, lifespan perspective to assess social processes, using multi-method assessments; (3) establishing global research collaborations to account for cultural influences on social processes and enable replications across laboratories and countries. The proposed line of research will contribute to globally develop and refine interventions that prevent CM and further positive relationships, which - likely through buffering the effects of chronic stress and corresponding allostatic load - foster resilience and improve mental and physical health, thereby reducing personal suffering and the societal and economic costs of CM and its consequences. Interventions targeting euthymia and psychological well-being are promising therapeutic concepts in this context.

COVID-19 and risk of retraumatization in adults with a past exposure to potentially traumatic events: A cross-cultural exploration across Egypt, Germany, and Italy.

AIMS: This study aims to: (1) explore the links between past exposure to potentially traumatic events, fear of contracting COVID-19 and perceived stress; (2) investigate how the exposure to traumagenic experiences affects one's locus of control over their health; and (3) examine fear, stress reactions and differences in health locus of control across three different sociocultural contexts. METHODS: A total of 524 adult participants were recruited from Egypt, Germany, and Italy through online channels. Self-reporting instruments were used to assess previous exposure to potentially traumatic events, PTSD symptoms, fear of COVID-19, perceived stress, and health locus of control. RESULTS: Our findings highlight differences in reaction to COVID-19 in relation to past exposure to potentially traumatic events and country of residence, both of which may inform tailored community-based intervention practices. CONCLUSION: The impact of COVID-19 might be particularly disruptive for people who survived potentially traumatic experiences. Nevertheless, the mass mental health impact of the COVID-19 pandemic varies across different sociocultural contexts.

Temporal Dynamics of Human Frontal and Cingulate Neural Activity During Conflict and Cognitive Control.

Cognitive control refers to the ability to produce flexible, goal-oriented behavior in the face of changing task demands and conflicting response tendencies. A classic cognitive control experiment is the Stroop-color naming task, which requires participants to name the color in which a word is written while inhibiting the tendency to read the word. By comparing stimuli with conflicting word-color associations to congruent ones, control processes over response tendencies can be isolated. We assessed the spatial specificity and temporal dynamics in the theta and gamma bands for regions engaged in detecting and resolving conflict in a cohort of 13 patients using a combination of high-resolution surface and depth recordings. We show that cognitive control manifests as a sustained increase in gamma band power, which correlates with response time. Conflict elicits a sustained gamma power increase but a transient theta power increase, specifically localized to the left cingulate sulcus and bilateral dorsolateral prefrontal cortex (DLPFC). Additionally, activity in DLPFC is affected by trial-by-trial modulation of cognitive control (the Gratton effect). Altogether, the sustained local neural activity in dorsolateral and medial regions is what determines the timing of the correct response.

Topography and timing of activity in right inferior frontal cortex and anterior insula for stopping movement.

Stopping incipient action activates both the right inferior frontal cortex (rIFC) and the anterior insula (rAI). Controversy has arisen as to whether these comprise a unitary cortical cluster-the rIFC/rAI-or whether rIFC is the primary stopping locus. To address this, we recorded directly from these structures while taking advantage of the high spatiotemporal resolution of closely spaced stereo-electro-encephalographic (SEEG) electrodes. We studied 12 patients performing a stop-signal task. On each trial they initiated a motor response (Go) and tried to stop to an occasional stop signal. Both the rIFC and rAI exhibited an increase in broadband gamma activity (BGA) after the stop signal and within the time of stopping (stop signal reaction time, SSRT), regardless of the success of stopping. The proportion of electrodes with this response was significantly greater in the rIFC than the rAI. Also, the rIFC response preceded that in the rAI. Last, while the BGA increase in rIFC occurred mainly prior to SSRT, the rAI showed a sustained increase in the beta and low gamma bands after the SSRT. In summary, the rIFC was activated soon after the stop signal, prior to and more robustly than the rAI, which on the other hand, showed a more prolonged response after the onset of stopping. Our results are most compatible with the notion that the rIFC is involved in triggering outright stopping in concert with a wider network, while the rAI is likely engaged by other processes, such as arousal, saliency, or behavioral adjustments. Hum Brain Mapp 39:189-203, 2018. © 2017 Wiley Periodicals, Inc.

Listener-speaker perceived distance predicts the degree of motor contribution to speech perception.

Listening speech sounds activates motor and premotor areas in addition to temporal and parietal brain regions. These activations are somatotopically localized according to the effectors recruited in the production of particular phonemes. Previous work demonstrated that transcranial magnetic stimulation (TMS) of speech motor centers somatotopically altered speech perception, suggesting a role for the motor system. However, these effects seemed to occur only under adverse listening conditions, suggesting that degraded speech may stimulate listeners to adopt unnatural neural strategies relying on motor centers. Here, we investigated whether naturally occurring interspeaker variability, which did not affect task difficulty, made a speech discrimination task sensitive to TMS interference. In this paradigm, TMS over tongue and lips motor representations somatotopically altered the discrimination time of speech. Furthermore, the TMS-induced effect correlated with listeners' similarity judgments between listeners' and speakers' speech productions. Thus, the degree of motor recruitment depends on the perceived distance between listener and speaker. This result supports the claim that discriminating others' speech pattern requires the contribution of the listener's own motor repertoire. We conclude that motor recruitment in speech perception can be a natural product of discriminating speech in a normally variable and unpredictable environment, not merely related to task difficulty.

Perceived Acceptability of Child Maltreatment as a Moderator of the Association Between Experiences of Child Maltreatment and Post-Traumatic Symptoms: A Cross-Cultural Study.

Despite the well-documented link between child maltreatment (CM) and mental health, evidence suggests substantial variability in the post-traumatic sequelae of CM across cultures. The perceived acceptability of CM in one's community might moderate the association between CM and mental health, but little research has been conducted on it so far. This study examined how the perceived acceptability of CM may influence the relationship between CM experiences and post-traumatic symptoms in individuals from four different continents and if the pattern of associations is the same across countries. We recruited a sample of 478 adults from Cameroon (n = 111), Canada (n = 137), Japan (n = 108), and Germany (n = 122). We administered online questionnaires and performed multiple group moderation analyses for total CM, neglect, physical abuse, emotional maltreatment, sexual abuse, and exposure to domestic violence (DV). A significant positive main effect of CM on post-traumatic symptoms was found in the overall sample and in Cameroon; in Germany, only neglect and emotional maltreatment were positively associated to post-traumatic symptoms. Moderation effects were identified; the perceived acceptability of neglect in Cameroon and Germany and of exposure to DV in Cameroon had a dampening effect on the relationship between CM experiences and post-traumatic symptoms. Our findings confirm that CM experiences entail long-term post-traumatic sequelae that can vary across cultures and CM subtypes and further our understanding of this issue by showing that the perceived acceptability of CM may be an understudied moderator.

A biophysically constrained brain connectivity model based on stimulation-evoked potentials.

BACKGROUND: Single-pulse electrical stimulation (SPES) is an established technique used to map functional effective connectivity networks in treatment-refractory epilepsy patients undergoing intracranial-electroencephalography monitoring. While the connectivity path between stimulation and recording sites has been explored through the integration of structural connectivity, there are substantial gaps, such that new modeling approaches may advance our understanding of connectivity derived from SPES studies. NEW METHOD: Using intracranial electrophysiology data recorded from a single patient undergoing stereo-electroencephalography (sEEG) evaluation, we employ an automated detection method to identify early response components, C1, from pulse-evoked potentials (PEPs) induced by SPES. C1 components were utilized for a novel topology optimization method, modeling 3D electrical conductivity to infer neural pathways from stimulation sites. Additionally, PEP features were compared with tractography metrics, and model results were analyzed with respect to anatomical features. RESULTS: The proposed optimization model resolved conductivity paths with low error. Specific electrode contacts displaying high error correlated with anatomical complexities. The C1 component strongly correlated with additional PEP features and displayed stable, weak correlations with tractography measures. COMPARISON WITH EXISTING METHOD: Existing methods for estimating neural signal pathways are imaging-based and thus rely on anatomical inferences. CONCLUSIONS: These results demonstrate that informing topology optimization methods with human intracranial SPES data is a feasible method for generating 3D conductivity maps linking electrical pathways with functional neural ensembles. PEP-estimated effective connectivity is correlated with but distinguished from structural connectivity. Modeled conductivity resolves connectivity pathways in the absence of anatomical priors.

Benchmarking signal quality and spatiotemporal distribution of interictal spikes in prolonged human iEEG recordings using CorTec wireless brain interchange.

Neuromodulation through implantable pulse generators (IPGs) represents an important treatment approach for neurological disorders. While the field has observed the success of state-of-the-art interventions, such as deep brain stimulation (DBS) or responsive neurostimulation (RNS), implantable systems face various technical challenges, including the restriction of recording from a limited number of brain sites, power management, and limited external access to the assessed neural data in a continuous fashion. To the best of our knowledge, for the first time in this study, we investigated the feasibility of recording human intracranial EEG (iEEG) using a benchtop version of the Brain Interchange (BIC) unit of CorTec, which is a portable, wireless, and externally powered implant with sensing and stimulation capabilities. We developed a MATLAB/SIMULINK-based rapid prototyping environment and a graphical user interface (GUI) to acquire and visualize the iEEG captured from all 32 channels of the BIC unit. We recorded prolonged iEEG (~ 24 h) from three human subjects with externalized depth leads using the BIC and commercially available clinical amplifiers simultaneously in the epilepsy monitoring unit (EMU). The iEEG signal quality of both streams was compared, and the results demonstrated a comparable power spectral density (PSD) in all the systems in the low-frequency band (< 80 Hz). However, notable differences were primarily observed above 100 Hz, where the clinical amplifiers were associated with lower noise floor (BIC-17 dB vs. clinical amplifiers < - 25 dB). We employed an established spike detector to assess and compare the spike rates in each iEEG stream. We observed over 90% conformity between the spikes rates and their spatial distribution captured with BIC and clinical systems. Additionally, we quantified the packet loss characteristic in the iEEG signal during the wireless data transfer and conducted a series of simulations to compare the performance of different interpolation methods for recovering the missing packets in signals at different frequency bands. We noted that simple linear interpolation has the potential to recover the signal and reduce the noise floor with modest packet loss levels reaching up to 10%. Overall, our results indicate that while tethered clinical amplifiers exhibited noticeably better noise floor above 80 Hz, epileptic spikes can still be detected successfully in the iEEG recorded with the externally powered wireless BIC unit opening the road for future closed-loop neuromodulation applications with continuous access to brain activity.

Beta activity in human anterior cingulate cortex mediates reward biases.

The rewards that we get from our choices and actions can have a major influence on our future behavior. Understanding how reward biasing of behavior is implemented in the brain is important for many reasons, including the fact that diminution in reward biasing is a hallmark of clinical depression. We hypothesized that reward biasing is mediated by the anterior cingulate cortex (ACC), a cortical hub region associated with the integration of reward and executive control and with the etiology of depression. To test this hypothesis, we recorded neural activity during a biased judgment task in patients undergoing intracranial monitoring for either epilepsy or major depressive disorder. We found that beta (12-30 Hz) oscillations in the ACC predicted both associated reward and the size of the choice bias, and also tracked reward receipt, thereby predicting bias on future trials. We found reduced magnitude of bias in depressed patients, in whom the beta-specific effects were correspondingly reduced. Our findings suggest that ACC beta oscillations may orchestrate the learning of reward information to guide adaptive choice, and, more broadly, suggest a potential biomarker for anhedonia and point to future development of interventions to enhance reward impact for therapeutic benefit.

Insula uses overlapping codes for emotion in self and others.

In daily life, we must recognize others' emotions so we can respond appropriately. This ability may rely, at least in part, on neural responses similar to those associated with our own emotions. We hypothesized that the insula, a cortical region near the junction of the temporal, parietal, and frontal lobes, may play a key role in this process. We recorded local field potential (LFP) activity in human neurosurgical patients performing two tasks, one focused on identifying their own emotional response and one on identifying facial emotional responses in others. We found matching patterns of gamma- and high-gamma band activity for the two tasks in the insula. Three other regions (MTL, ACC, and OFC) clearly encoded both self- and other-emotions, but used orthogonal activity patterns to do so. These results support the hypothesis that the insula plays a particularly important role in mediating between experienced vs. observed emotions.

The disembodiment effect of negation: negating action-related sentences attenuates their interference on congruent upper limb movements.

Human languages can express opposite propositions by means of the negative operator "not," which turns affirmative sentences into negative ones. Psycholinguistic research has indicated that negative meanings are formed by transiently reducing the access to mental representations of negated conceptual information. Neuroimaging studies have corroborated these findings, showing reduced activation of concept-specific embodied neural systems by negative versus affirmative sentences. This "disembodiment effect" of sentential negation should have two distinct consequences: first, the embodied systems should be computationally more free to support concurrent tasks when processing negative than affirmative sentences; second, the computational interference should only be reduced when there is a strict semantic congruency between the negated concept and the referent targeted by concurrent tasks. We tested these two predictions in two complementary experiments involving the comprehension of action-related sentences and kinematic measurements of its effects on concurrent, congruent actions. Sentences referred to actions involving either proximal or distal arm musculature. In experiment 1, requiring a proximal arm movement, we found interference reduction for negative proximal sentences. In experiment 2, requiring a distal arm movement, we found interference reduction for negative distal sentences. This dissociation provides the first conclusive evidence in support of a disembodiment theory of negation. We conclude that the computational cost resulting from the insertion of an additional lexical item ("not") in negative sentences is compensated by solely storing a concept in affirmative form in semantic memory, since its negative counterpart can be produced by transiently reducing the access to such stored semantic information.

How are experiences and acceptability of child maltreatment related to resilience and posttraumatic growth: a cross cultural study.

Background: Post-traumatic growth (PTG) and resilience, regarded as positive psychological change following a traumatic experience, are under-researched across cultures in people exposed to child maltreatment (CM).Objective: We investigated how experiences and the perceived acceptability of CM are related to resilience and PTG in countries with different cultures, living standards, and gross national income.Method: A total of 478 adults from Cameroon (n = 111), Canada (n = 137), Japan (n = 108), and Germany (n = 122) completed an online survey with self-reported questionnaires, including the Brief Resilience Scale and the Post Traumatic Growth Inventory-Short Form.Results: Across countries, self-reported male gender and age were positively associated with resilience, while experiences of physical abuse and emotional maltreatment were negatively associated with resilience. Experiences of emotional maltreatment were positively associated with PTG. Higher levels of PTG and resilience were found amongst Cameroonian participants as compared to other countries.Conclusion: Our results suggest that positive changes following CM can vary significantly across cultures and that experiences of specific CM subtypes, but not the perceived acceptability of CM, may be important for a deeper understanding of how individuals overcome trauma and develop salutogenic outcomes. Our findings may inform CM intervention programmes for an enhanced cultural sensitivity.

Across the four countries (Canada, Cameroon, Germany, Japan), more experiences of physical abuse and emotional maltreatment were associated with lower resilience; more experiences of emotional maltreatment were associated with greater post-traumatic growth.Higher levels of post-traumatic growth and resilience were found in Cameroon as compared to other countries.Positive changes following child maltreatment vary across cultures and experiences of specific child maltreatment subtypes, but the perceived acceptability of child maltreatment did not exert an influence on salutogenic post-traumatic outcomes.

Associations between experiences of childhood maltreatment and perceived acceptability of child maltreatment: A cross-cultural and exploratory study.

BACKGROUND: Acceptable parental behaviors and practices toward a child vary across countries and may impact the risk of exposure to maltreatment. Conversely, prior experiences of maltreatment as a child may influence the acceptability of child maltreatment (CM) behaviors. OBJECTIVE: This exploratory study examined the association between CM experiences and perceived acceptability of CM using data from four countries representing different cultures, living standards, and gross national income. PARTICIPANTS AND SETTING: We recruited a convenience sample of 478 adults from Cameroon (n = 111), Canada (n = 137), Japan (n = 108), and Germany (n = 122) through online postings on social media. METHODS: We administered questionnaires and conducted a three-stage hierarchical multiple regression with perceived acceptability of CM subscales as the dependent variable. RESULTS: In all countries, higher scores of childhood neglect were associated with greater perceived acceptability of neglect in one's community (p < .001). Equally, our results showed that higher scores of childhood neglect or sexual abuse were associated with greater perceived acceptability of sexual abuse (p < .044). However, we did not find a significant relationship between other forms of CM (i.e., physical abuse, emotional maltreatment, exposure to domestic violence), and their perceived acceptability. CONCLUSIONS: Our findings suggest that experiences of some CM types, namely neglect and sexual abuse, may be associated with the perception that these are more acceptable within one's community. Perceived acceptability of CM might be a driver that can either prevent or perpetuate CM. Therefore, intervention and prevention programs could incorporate a deeper cross-cultural understanding and assessment of these social norms in order to foster meaningful behavioral changes.

A biophysically constrained brain connectivity model based on stimulation-evoked potentials.

Background: Single-pulse electrical stimulation (SPES) is an established technique used to map functional effective connectivity networks in treatment-refractory epilepsy patients undergoing intracranial-electroencephalography monitoring. While the connectivity path between stimulation and recording sites has been explored through the integration of structural connectivity, there are substantial gaps, such that new modeling approaches may advance our understanding of connectivity derived from SPES studies. New Method: Using intracranial electrophysiology data recorded from a single patient undergoing sEEG evaluation, we employ an automated detection method to identify early response components, C1, from pulse-evoked potentials (PEPs) induced by SPES. C1 components were utilized for a novel topology optimization method, modeling 3D conductivity propagation from stimulation sites. Additionally, PEP features were compared with tractography metrics, and model results were analyzed with respect to anatomical features. Results: The proposed optimization model resolved conductivity paths with low error. Specific electrode contacts displaying high error correlated with anatomical complexities. The C1 component strongly correlates with additional PEP features and displayed stable, weak correlations with tractography measures. Comparison with existing methods: Existing methods for estimating conductivity propagation are imaging-based and thus rely on anatomical inferences. Conclusions: These results demonstrate that informing topology optimization methods with human intracranial SPES data is a feasible method for generating 3D conductivity maps linking electrical pathways with functional neural ensembles. PEP-estimated effective connectivity is correlated with but distinguished from structural connectivity. Modeled conductivity resolves connectivity pathways in the absence of anatomical priors.

Brain mechanisms underlying the emotion processing bias in treatment-resistant depression.

Depression is associated with a cognitive bias towards negative information and away from positive information. This biased emotion processing may underlie core depression symptoms, including persistent feelings of sadness or low mood and a reduced capacity to experience pleasure. The neural mechanisms responsible for this biased emotion processing remain unknown. Here, we had a unique opportunity to record stereotactic electroencephalography (sEEG) signals in the amygdala and prefrontal cortex (PFC) from 5 treatment-resistant depression (TRD) patients and 12 epilepsy patients (as control) while they participated in an affective bias task in which happy and sad faces were rated. First, compared with the control group, patients with TRD showed increased amygdala responses to sad faces in the early stage (around 300 ms) and decreased amygdala responses to happy faces in the late stage (around 600 ms) following the onset of faces. Further, during the late stage of happy face processing, alpha-band activity in PFC as well as alpha-phase locking between the amygdala and PFC were significantly greater in TRD patients compared to the controls. Second, after deep brain stimulation (DBS) delivered to bilateral subcallosal cingulate (SCC) and ventral capsule/ventral striatum (VC/VS), atypical amygdala and PFC processing of happy faces in TRD patients remitted toward the normative pattern. The increased amygdala activation during the early stage of sad face processing suggests an overactive bottom-up processing system in TRD. Meanwhile, the reduced amygdala response during the late stage of happy face processing could be attributed to inhibition by PFC through alpha-band oscillation, which can be released by DBS in SCC and VC/VS.

Stereo-EEG-guided network modulation for psychiatric disorders: Surgical considerations.

BACKGROUND: Deep brain stimulation (DBS) and other neuromodulatory techniques are being increasingly utilized to treat refractory neurologic and psychiatric disorders. OBJECTIVE: /Hypothesis: To better understand the circuit-level pathophysiology of treatment-resistant depression (TRD) and treat the network-level dysfunction inherent to this challenging disorder, we adopted an approach of inpatient intracranial monitoring borrowed from the epilepsy surgery field. METHODS: We implanted 3 patients with 4 DBS leads (bilateral pair in both the ventral capsule/ventral striatum and subcallosal cingulate) and 10 stereo-electroencephalography (sEEG) electrodes targeting depression-relevant network regions. For surgical planning, we used an interactive, holographic visualization platform to appreciate the 3D anatomy and connectivity. In the initial surgery, we placed the DBS leads and sEEG electrodes using robotic stereotaxy. Subjects were then admitted to an inpatient monitoring unit for depression-specific neurophysiological assessments. Following these investigations, subjects returned to the OR to remove the sEEG electrodes and internalize the DBS leads to implanted pulse generators. RESULTS: Intraoperative testing revealed positive valence responses in all 3 subjects that helped verify targeting. Given the importance of the network-based hypotheses we were testing, we required accurate adherence to the surgical plan (to engage DBS and sEEG targets) and stability of DBS lead rotational position (to ensure that stimulation field estimates of the directional leads used during inpatient monitoring were relevant chronically), both of which we confirmed (mean radial error 1.2±0.9 mm; mean rotation 3.6±2.6°). CONCLUSION: This novel hybrid sEEG-DBS approach allows detailed study of the neurophysiological substrates of complex neuropsychiatric disorders.

Distinct population and single-neuron selectivity for executive and episodic processing in human dorsal posterior cingulate.

Posterior cingulate cortex (PCC) is an enigmatic region implicated in psychiatric and neurological disease, yet its role in cognition remains unclear. Human studies link PCC to episodic memory and default mode network (DMN), while findings from the non-human primate emphasize executive processes more associated with the cognitive control network (CCN) in humans. We hypothesized this difference reflects an important functional division between dorsal (executive) and ventral (episodic) PCC. To test this, we utilized human intracranial recordings of population and single unit activity targeting dorsal PCC during an alternated executive/episodic processing task. Dorsal PCC population responses were significantly enhanced for executive, compared to episodic, task conditions, consistent with the CCN. Single unit recordings, however, revealed four distinct functional types with unique executive (CCN) or episodic (DMN) response profiles. Our findings provide critical electrophysiological data from human PCC, bridging incongruent views within and across species, furthering our understanding of PCC function.