A prevalent model is that sharp-wave ripples (SWR) arise ‘spontaneously’ in CA3 and propagate recent memory traces outward to the neocortex to facilitate memory consolidation there. Using voltage and extracellular glutamate transient recording over widespread regions of mice dorsal neocortex in relation to CA1 multiunit activity (MUA) and SWR, we find that the largest SWR-related modulation occurs in retrosplenial cortex; however, contrary to the unidirectional hypothesis, neocortical activation exhibited a continuum of activation timings relative to SWRs, varying from leading to lagging. Thus, contrary to the model in which SWRs arise ‘spontaneously’ in the hippocampus, neocortical activation often precedes SWRs and may thus constitute a trigger event in which neocortical information seeds associative reactivation of hippocampal ‘indices’. This timing continuum is consistent with a dynamics in which older, more consolidated memories may in fact initiate the hippocampal-neocortical dialog, whereas reactivation of newer memories may be initiated predominantly in the hippocampus.

Brain areas within the lateral parietal cortex (LPC) and ventral temporal cortex (VTC) have been shown to code for abstract quantity representations and for symbolic numerical representations, respectively. To explore the fast dynamics of activity within each region and the interaction between them, we used electrocorticography recordings from 16 neurosurgical subjects implanted with grids of electrodes over these two regions and tracked the activity within and between the regions as subjects performed three different numerical tasks. Although our results reconfirm the presence of math-selective hubs within the VTC and LPC, we report here a remarkable heterogeneity of neural responses within each region at both millimeter and millisecond scales. Moreover, we show that the heterogeneity of response profiles within each hub mirrors the distinct patterns of functional coupling between them. Our results support the existence of multiple bidirectional functional loops operating between discrete populations of neurons within the VTC and LPC during the visual processing of numerals and the performance of arithmetic functions. These findings reveal information about the dynamics of numerical processing in the brain and also provide insight into the fine-grained functional architecture and connectivity within the human brain.A lthough the ability to approximate or compare rough quantities is present even in human infants (1) and in other species such as nonhuman primates (2-4) and birds (5), the association of exact quantities with symbols (e.g., the numeral "10") or verbal representations (e.g., the word "ten") is unique to humans exposed to such culturally learned entities (6-8). Moreover, dissociable number-and quantity-related behavioral deficits (i.e., deficits relating to symbolic or verbal numerical representations versus abstract quantity representations) are associated with different lesion locations within the brain (9-14). These observations in part motivated the Triple Code model positing that the human brain contains three different numerical representations: symbolic, verbal, and abstract quantity, each coded in a different brain region (15,16). The model also predicts that, depending on task demands (e.g., simple visual recognition of a numeral versus determining the larger of two numerals versus verbal naming of a numeral), all or a subset of these brain regions interact with each other (15, 16).Neuroimaging, electrophysiology, and lesion studies in both humans and nonhuman primates have long implicated the parietal lobe, particularly the anterior segment of the intraparietal sulcus (aIPS), in abstract quantity representations irrespective of the modality of presentation (e.g., "4" vs. "four" vs. "::"), with specific neurons or neuronal populations exhibiting tuning around a preferred numerosity (4, 17-25). Moreover, brain activity within this region and its functional and anatomical connectivity with other brain regions are correlated with mathematical performance in individual subjects (26)(27)(28)(29),...

Keywords 19Hippocampus, neocortex, hippocampal-cortical interaction, memory consolidation, sharp-wave 20 ripple, multi-unit activity, wide-field mesoscale optical imaging, local field potential, head-21 restrained sleep 22 23 24 25Abstract 26A prevalent model is that sharp-wave ripples (SWR) arise 'spontaneously' in CA3 and 27 propagate recent memory traces outward to the neocortex to facilitate memory consolidation 28 there. Using voltage and extracellular glutamate transient recording over widespread regions of 29 mice dorsal neocortex in relation to CA1 multiunit activity (MUA) and SWR, we find that the 30 largest SWR-related modulation occurs in retrosplenial cortex; however, contrary to the 31 unidirectional hypothesis, neocortical activation exhibited a continuum of activation timings 32 relative to SWRs, varying from leading to lagging. Thus, contrary to the model in which SWRs 33 arise 'spontaneously' in the hippocampus, neocortical activation often precedes SWRs and may 34 thus constitute a trigger event in which neocortical information seeds associative reactivation of 35

The insulo-opercular network functions critically not only in encoding taste, but also in guiding behavior based on anticipated food availability. However, there remains no direct measurement of insulo-opercular activity when humans anticipate taste. Here, we collect direct, intracranial recordings during a food task that elicits anticipatory and consummatory taste responses, and during ad libitum consumption of meals. While cue-specific high-frequency broadband (70–170 Hz) activity predominant in the left posterior insula is selective for taste-neutral cues, sparse cue-specific regions in the anterior insula are selective for palatable cues. Latency analysis reveals this insular activity is preceded by non-discriminatory activity in the frontal operculum. During ad libitum meal consumption, time-locked high-frequency broadband activity at the time of food intake discriminates food types and is associated with cue-specific activity during the task. These findings reveal spatiotemporally-specific activity in the human insulo-opercular cortex that underlies anticipatory evaluation of food across both controlled and naturalistic settings.

A long-standing goal of spinal cord injury research is to develop effective repair strategies, which can restore motor and sensory functions to near-normal levels. Recent advances in clinical management of spinal cord injury have significantly improved the prognosis, survival rate and quality of life in patients with spinal cord injury. In addition, a significant progress in basic science research has unraveled the underlying cellular and molecular events of spinal cord injury. Such efforts enabled the development of pharmacologic agents, biomaterials and stem-cell based therapy. Despite these efforts, there is still no standard care to regenerate axons or restore function of silent axons in the injured spinal cord. These challenges led to an increased focus on another therapeutic approach, namely neuromodulation. In multiple animal models of spinal cord injury, epidural electrical stimulation of the spinal cord has demonstrated a recovery of motor function. Emerging evidence regarding the efficacy of epidural electrical stimulation has further expanded the potential of epidural electrical stimulation for treating patients with spinal cord injury. However, most clinical studies were conducted on a very small number of patients with a wide range of spinal cord injury. Thus, subsequent studies are essential to evaluate the therapeutic potential of epidural electrical stimulation for spinal cord injury and to optimize stimulation parameters. Here, we discuss cellular and molecular events that continue to damage the injured spinal cord and impede neurological recovery following spinal cord injury. We also discuss and summarize the animal and human studies that evaluated epidural electrical stimulation in spinal cord injury.

Objective: Cervical spondylotic myelopathy (CSM) is a degenerative disorder leading to progressive decline in spinal cord function. Cervical laminoplasty (CLP) and cervical laminectomy with fusion (CLF) are standard treatments for multilevel CSM. However, it is still unclear whether one procedure over the other provides better outcomes. Here, we performed a comprehensive review of published articles that compare the clinical outcomes and costs between CLP and CLF for CSM. Methods: A literature search was performed using PubMed, Web of Science, and Cochrane databases. Strict exclusion criteria were applied, and included articles were then assessed for publication year, study design, and significant differences in outcome variables. Results: From 519 studies identified with search terms, 38 studies were included for the qualitative analysis. Statistically significant differences in the clinical outcomes and costs were found in 18 studies. Eleven studies were prospective or retrospective, and 8 studies were meta-analyses. For the outcome variables of interest, results were reported by classifying into prospective studies, retrospective studies, and meta-analyses. Conclusion: CLP and CLF are 2 of the most commonly performed surgical procedures for the treatment of CSM. Although CLP and CLF each provide satisfactory clinical outcomes for patients with CMS, CLP may result in better cervical range of motion and less cost, length of stay, operation time, blood loss, paraspinal muscular atrophy, and rate of nerve palsies as compared to CLF. The major limitation of CLP versus CLF comparison studies includes the heterogeneity in techniques and preoperative criteria. Thus, further validation and investigations in larger cohorts will be required.

Background: As a growing number of patients seek consultations for increasingly complex and costly spinal surgery, it is of both clinical and economic value to investigate the role for second opinions (SOs). Here, we summarized and focused on the shortcomings of 14 studies regarding the role and value of SOs before proceeding with spine surgery. Methods: Utilizing PubMed, Google Scholar, and Scopus, we identified 14 studies that met the inclusion criteria that included: English, primary articles, and studies published in the past 20 years. Results: We identified the following findings regarding SO for spine surgery: (1) about 40.6% of spine consultations are SO cases; (2) 61.3% of those received a discordant SO; (3) 75% of discordant SOs recommended conservative management; and (4) SO discordance applied to a variety of procedures. Conclusion: The 14 studies reviewed regarding SOs in spine surgery showed that half of the SOs differed from those given in the initial consultation and that SOs in spine surgery can have a substantial impact on patient care. Absent are prospective studies investigating the impact of following a first versus second opinion. These studies are needed to inform the potential benefit of universal implementation of SOs before major spine operations to potentially reduce the frequency and type/extent of surgery.

OBJECTIVEMinimally invasive anterior lumbar interbody fusion surgery (MIS ALIF) is a technique that restores disc height and lumbar lordosis through a smaller exposure and less soft-tissue trauma compared to open approaches. The mini-open and laparoscopic assistance techniques are two main forms of MIS ALIF. The authors conducted a systematic review that sought to critically summarize the literature on back pain following MIS ALIF.METHODSIn March 2020, the authors searched the PubMed, Web of Science, and Cochrane Library databases for studies describing back pain visual analog scale (VAS) outcomes after MIS ALIF. The following exclusion criteria were applied to studies evaluated in full text: 1) the study included fewer than 20 patients, 2) the mean follow-up duration was shorter than 12 months, 3) the study did not report back pain VAS score as an outcome measure, and 4) MIS ALIF was not studied specifically. The methodology for the included studies were evaluated for potential biases and assigned a level of evidence.RESULTSThere were a total of 552 patients included from 13 studies. The most common biases were selection and interviewer bias. The majority of studies were retrospective. The mean sample size was 42.3 patients. The mean follow-up duration was approximately 41.8 months. The mean postoperative VAS reduction was 5.1 points. The mean VAS reduction for standalone grafts was 5.9 points, and 5.0 points for those augmented with posterior fixation. The most common complications included bladder or urinary dysfunction, infection, and hardware-related complications.CONCLUSIONSThis was a systematic review of back pain outcomes following MIS ALIF. Back pain VAS score was reduced postoperatively across all studies. The complication rates were low overall. MIS ALIF is safe and effective at reducing back pain in appropriate patient populations.