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Neurosurgical Focus May 2016Disorders of learning and memory have a large social and economic impact in today's society. Unfortunately, existing medical treatments have shown limited clinical... (Review)
Review
Disorders of learning and memory have a large social and economic impact in today's society. Unfortunately, existing medical treatments have shown limited clinical efficacy or potential for modification of the disease course. Deep brain stimulation is a successful treatment for movement disorders and has shown promise in a variety of other diseases including psychiatric disorders. The authors review the potential of neuromodulation for the treatment of disorders of learning and memory. They briefly discuss learning circuitry and its involvement in Alzheimer disease and traumatic brain injury. They then review the literature supporting various targets for neuromodulation to improve memory in animals and humans. Multiple targets including entorhinal cortex, fornix, nucleus basalis of Meynert, basal ganglia, and pedunculopontine nucleus have shown a promising potential for improving dysfunctional memory by mechanisms such as altering firing patterns in neuronal networks underlying memory and increasing synaptic plasticity and neurogenesis. Significant work remains to be done to translate these findings into durable clinical therapies.
Topics: Animals; Deep Brain Stimulation; Humans; Learning Disabilities; Memory Disorders; Optogenetics; Recovery of Function; Stroke; Translational Research, Biomedical
PubMed: 27132526
DOI: 10.3171/2016.3.FOCUS162 -
Brain and Nerve = Shinkei Kenkyu No... Jun 2017Pure amnesia (amnesic syndrome) is an organic brain syndrome characterized by impairment in episodic memory, with either an anterograde or sometimes retrograde loss of...
Pure amnesia (amnesic syndrome) is an organic brain syndrome characterized by impairment in episodic memory, with either an anterograde or sometimes retrograde loss of memories. Although episodic memory is impaired, semantic memory, immediate memory, and procedural memory are preserved. The Papez circuit is a network of nerve fibers and nerve centers that starts and ends in the hippocampus travelling by way of the fornix, mammillary bodies, anterior thalamic nuclei, cingulate gyrus, and parahippocampal gyrus. A lesion restricted to this circuit often produces pure amnesia. Regions concerned with the Yakovlev circuit also have an important role in memory. Clinical cases of pure amnesia caused by cerebrovascular disease presented following brain imaging and resulted from various different lesions. The cases identified were predominantly thalamic amnesia and hippocampal amnesia. Thalamic amnesia often resulted from an infarction in the territory of the thalamotuberal artery and paramedian thalamic artery although thalamic hemorrhage in medial portion of thalamus also produced pure amnesia. Hippocampal amnesia usually occurred following an infarction in the temporal branches of posterior cerebral artery. Cases of retrosplenial amnesia caused by subcortical hematoma and infarction in the retrosplenial region are also described. In addition, cases of pure amnesia resulting from an infarction in the fornix, mammillary body hemorrhage, and caudate hemorrhage are also shown.
Topics: Amnesia; Cerebrovascular Disorders; Hippocampus; Humans; Memory; Neural Pathways; Thalamus
PubMed: 28596462
DOI: 10.11477/mf.1416200791 -
Surgical Oncology Clinics of North... Jul 2023Radiotherapy remains a cornerstone treatment of brain metastases. With new treatment advances, patients with brain metastases are living longer, and finding solutions... (Review)
Review
Radiotherapy remains a cornerstone treatment of brain metastases. With new treatment advances, patients with brain metastases are living longer, and finding solutions for mitigating treatment-related neurotoxicity and improving quality of life is important. Historically, whole-brain radiation therapy (WBRT) was widely used but treatment options such as hippocampal sparing WBRT and stereotactic radiosurgery (SRS) have emerged as promising alternatives. Herein, we discuss the recent advances in radiotherapy for brain metastases including the sparing of critical structures that may improve long-term neurocognitive outcomes (eg, hippocampus, fornix) that may improve long-term neurocognitive outcome, evidence supporting preoperative and fractionated-SRS, and treatment strategies for managing radiation necrosis.
Topics: Humans; Brain Neoplasms; Quality of Life; Cranial Irradiation; Radiosurgery; Hippocampus
PubMed: 37182993
DOI: 10.1016/j.soc.2023.02.007 -
Neurosurgical Review Apr 2022The historical evolution of the fornix has not been sufficiently reviewed in the literature. In this article, we follow this evolution from the first mention of the... (Review)
Review
The historical evolution of the fornix has not been sufficiently reviewed in the literature. In this article, we follow this evolution from the first mention of the fornix in animal dissections of the second century AD, to the legalization of cadaver dissection in the 1300 s, to the introduction of neural staining techniques and the microscope in the seventeenth century, to today. We summarize the focus of fornix studies on memory to reveal its relationship with the hippocampus. We then cover the detection of the fornix and its neural connections noninvasively with the advancement of radiological imaging techniques. Finally, we discuss the prominence of the fornix as a target for deep brain stimulation in Alzheimer's disease and post-traumatic brain injury memory disorders.
Topics: Alzheimer Disease; Animals; Deep Brain Stimulation; Fornix, Brain; Hippocampus; Humans
PubMed: 34498223
DOI: 10.1007/s10143-021-01635-w -
Nature Communications Dec 2022Deep brain stimulation (DBS) to the fornix is an investigational treatment for patients with mild Alzheimer's Disease. Outcomes from randomized clinical trials have...
Deep brain stimulation (DBS) to the fornix is an investigational treatment for patients with mild Alzheimer's Disease. Outcomes from randomized clinical trials have shown that cognitive function improved in some patients but deteriorated in others. This could be explained by variance in electrode placement leading to differential engagement of neural circuits. To investigate this, we performed a post-hoc analysis on a multi-center cohort of 46 patients with DBS to the fornix (NCT00658125, NCT01608061). Using normative structural and functional connectivity data, we found that stimulation of the circuit of Papez and stria terminalis robustly associated with cognitive improvement (R = 0.53, p < 0.001). On a local level, the optimal stimulation site resided at the direct interface between these structures (R = 0.48, p < 0.001). Finally, modulating specific distributed brain networks related to memory accounted for optimal outcomes (R = 0.48, p < 0.001). Findings were robust to multiple cross-validation designs and may define an optimal network target that could refine DBS surgery and programming.
Topics: Humans; Alzheimer Disease; Brain; Deep Brain Stimulation; Fornix, Brain; Thalamus; Randomized Controlled Trials as Topic
PubMed: 36517479
DOI: 10.1038/s41467-022-34510-3