Postmortem Dissections of the Papez Circuit and Nonmotor Targets for Functional Neurosurgery

Junior, Tancredo Alcântara Ferreira; Middlebrooks, Erik H.; Tzu, Wen Hung; Neto, Mateus Reghin; Holanda, Vanessa M.

doi:10.1016/j.wneu.2020.09.088

Cited by 15 publications

(7 citation statements)

References 69 publications

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“…21 Our observations may help explain the findings of Schaper et al, 22 where HFS produced greater seizure freedom with stimulation near the junction of the mammillothalamic tract and ANT, as well as the anterior ANT. Since the limbic circuit enters ANT through the mammillothalamic tract and then exits the anterior pole of ANT to extend to the ACC, 9 HFS in this region would be expected to stimulate these white matter connections and produce a net downstream activation, as seen in our study. Lastly, our results are in general agreement with findings from invasive monitoring and stimulation of the fornix, which subsequently connects to ANT via the mammillary body and mammillothalamic tract.…”

Section: Figure 5 Heat Maps Showing Spatial Similarity Between the Es...mentioning

confidence: 62%

“…HFS produced significant activation within multiple cortical and subcortical regions (Figure 3A and 3B). In particular, there was activation of the limbic network 8,9 including the hippocampus, anterior cingulate cortex (ACC), amygdala, ANT, medial prefrontal cortex, and ventral tegmental area. Additionally, regions of the DMN 10 were also activated.…”

Section: Dbs Activationmentioning

confidence: 99%

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Acute Brain Activation Patterns of High- Versus Low-Frequency Stimulation of the Anterior Nucleus of the Thalamus During Deep Brain Stimulation for Epilepsy

Middlebrooks¹,

Jain²,

Okromelidze³

et al. 2021

Neurosurg.

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BACKGROUND Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is an increasingly utilized treatment of drug-resistant epilepsy. To date, the effect of high-frequency stimulation (HFS) vs low-frequency stimulation (LFS) in ANT DBS is poorly understood. OBJECTIVE To assess differences in the acute effect of LFS vs HFS in ANT DBS utilizing blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI). METHODS In this prospective study of 5 patients with ANT DBS for epilepsy, BOLD activation and deactivation were modeled for 145-Hz and 30-Hz ANT stimulation using an fMRI block design. Data were analyzed with a general linear model and combined via 2-stage mixed-effects analysis. Z-score difference maps were nonparametrically thresholded using cluster threshold of z > 3.1 and a (corrected) cluster significance threshold of P = .05. RESULTS HFS produced significantly greater activation within multiple regions, in particular the limbic and default mode network (DMN). LFS produced minimal activation and failed to produce significant activation within these same networks. HFS produced widespread cortical and subcortical deactivation sparing most of the limbic and DMN regions. Meanwhile, LFS produced deactivation in most DMN and limbic structures. CONCLUSION Our results show that HFS and LFS produce substantial variability in both local and downstream network effects. In particular, largely opposing effects were identified within the limbic network and DMN. These findings may serve as a mechanistic basis for understanding the potential of HFS vs LFS in various epilepsy syndromes.

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Section: Figure 5 Heat Maps Showing Spatial Similarity Between the Es...mentioning

confidence: 62%

Section: Dbs Activationmentioning

confidence: 99%

Acute Brain Activation Patterns of High- Versus Low-Frequency Stimulation of the Anterior Nucleus of the Thalamus During Deep Brain Stimulation for Epilepsy

Middlebrooks¹,

Jain²,

Okromelidze³

et al. 2021

Neurosurg.

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“…The ANT is located in the anterior dorsal thalamus along the medial border with a Yshaped internal medullary lamina separating it from the adjacent nuclei. 36,37 Grewal et al have previously shown that the location of ANT at the termination of the mammillothalamic tract, as well as the adjacent lamina, can be exploited to visualise ANT by using white matter suppression in the FGATIR sequence. 26 The FGATIR sequence is a fast and easily implementable sequence with superb visualisation of ANT; however, other key nuclei, such as the centromedian and parafascicular, are not well resolved.…”

Section: Discussionmentioning

confidence: 99%

Edge-enhancing gradient echo with multi-image co-registration and averaging (EDGE-MICRA) for targeting thalamic centromedian and parafascicular nuclei

et al. 2021

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Background and purpose Deep brain stimulation of the thalamus is an effective treatment for multiple neurological disorders. The centromedian and parafascicular nuclei are recently emerging targets for multiple conditions, such as epilepsy and Tourette syndrome; however, their limited visibility on conventional magnetic resonance imaging sequences has been a major obstacle. The goal of this study was to demonstrate the feasibility of a high-resolution and high-contrast targeting sequence for centromedian-parafascicular deep brain stimulation using a recently described magnetic resonance imaging sequence, three-dimensional edge-enhancing gradient echo. Methods The three-dimensional edge-enhancing gradient echo sequence was performed on a normal volunteer for a total of six acquisitions. Multi-image co-registration and averaging was performed by first co-registering each of the six scans and then averaging to produce an edge-enhancing gradient echo-multi-image co-registration and averaging scan. The averaging was also performed for two, three, four and five scans to assess the change in the signal-to-noise ratio and identify the ideal balance of image quality and scan time. Results The edge-enhancing gradient echo-multi-image co-registration and averaging scan allowed clear boundary delineation of the centromedian and parafascicular nuclei. The signal-to-noise ratio increased as a function of increasing scan number, but the added gain was small beyond four scans for the imaging parameters used in this study. Conclusions The recently described three-dimensional edge-enhancing gradient echo sequence provides an easily implementable approach, using widely available magnetic resonance imaging technology without complex post-processing techniques, to delineate centromedian and parafascicular nuclei for deep brain stimulation targeting.

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“…In the 1930s, Papez et al discovered that there was a major circuit in the limbic system, called the Papez circuit, involving hippocampus→fornix→papillary body→papillary thalamic tract→prethalamic nucleus→cingulate gyrus→ hippocampus [31,32] (Figure 1). The hippocampus is the central part of this circuit.…”

Section: The Papez Circuitmentioning

confidence: 99%

Neural Circuits and Some New Factors Involved in Hippocampal Memory

Jing¹,

Cai²,

Li³

et al. 2022

Hippocampus - Cytoarchitecture and Diseases

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Humans and other primates have memory, and the hippocampus plays a critical role in this process. The neural circuitry is one of the structural foundations for the hippocampus in exerting memory function. To understand the relationship between the hippocampus and memory, we need to understand neural circuits. Past research has identified several classical neural circuits involved in memory. Although there are challenges with the study of hippocampal neural circuits, research on this topic has continued, and some progress has been made. Here, we discuss recent advances in our understanding of hippocampal neural circuit mechanisms and some of the newly discovered factors that affect memory. Substantial progress has been made regarding hippocampal memory circuits and Alzheimer’s disease. However, it is unclear whether these novel findings regarding hippocampal memory circuits hold promise for human memory studies. Additional research on this topic is needed.

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Postmortem Dissections of the Papez Circuit and Nonmotor Targets for Functional Neurosurgery

Cited by 15 publications

References 69 publications

Acute Brain Activation Patterns of High- Versus Low-Frequency Stimulation of the Anterior Nucleus of the Thalamus During Deep Brain Stimulation for Epilepsy

Acute Brain Activation Patterns of High- Versus Low-Frequency Stimulation of the Anterior Nucleus of the Thalamus During Deep Brain Stimulation for Epilepsy

Edge-enhancing gradient echo with multi-image co-registration and averaging (EDGE-MICRA) for targeting thalamic centromedian and parafascicular nuclei

Neural Circuits and Some New Factors Involved in Hippocampal Memory

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