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Neuron Mar 2021Human brain pathways supporting language and declarative memory are thought to have differentiated substantially during evolution. However, cross-species comparisons are...
Human brain pathways supporting language and declarative memory are thought to have differentiated substantially during evolution. However, cross-species comparisons are missing on site-specific effective connectivity between regions important for cognition. We harnessed functional imaging to visualize the effects of direct electrical brain stimulation in macaque monkeys and human neurosurgery patients. We discovered comparable effective connectivity between caudal auditory cortex and both ventro-lateral prefrontal cortex (VLPFC, including area 44) and parahippocampal cortex in both species. Human-specific differences were clearest in the form of stronger hemispheric lateralization effects. In humans, electrical tractography revealed remarkably rapid evoked potentials in VLPFC following auditory cortex stimulation and speech sounds drove VLPFC, consistent with prior evidence in monkeys of direct auditory cortex projections to homologous vocalization-responsive regions. The results identify a common effective connectivity signature in human and nonhuman primates, which from auditory cortex appears equally direct to VLPFC and indirect to the hippocampus. VIDEO ABSTRACT.
Topics: Adolescent; Adult; Animals; Auditory Cortex; Brain Mapping; Electric Stimulation; Female; Frontal Lobe; Humans; Macaca mulatta; Magnetic Resonance Imaging; Male; Middle Aged; Neural Pathways; Parahippocampal Gyrus; Prefrontal Cortex; Species Specificity; Temporal Lobe; Young Adult
PubMed: 33482086
DOI: 10.1016/j.neuron.2020.12.026 -
The Journal of Neuroscience : the... Nov 2019The parahippocampal region is thought to be critical for memory and spatial navigation. Within this region lies the parasubiculum, a small structure that exhibits strong...
The parahippocampal region is thought to be critical for memory and spatial navigation. Within this region lies the parasubiculum, a small structure that exhibits strong theta modulation, contains functionally specialized cells, and projects to layer II of the medial entorhinal cortex (MEC). Thus, it is uniquely positioned to influence firing of spatially modulated cells in the MEC and play a key role in the internal representation of the external environment. However, the basic neuronal composition of the parasubiculum remains largely unknown, and its border with the MEC is often ambiguous. We combine electrophysiology and immunohistochemistry in adult mice (both sexes) to define first, the boundaries of the parasubiculum, and second, the major cell types found in this region. We find distinct differences in the colabeling of molecular markers between the parasubiculum and the MEC, allowing us to clearly separate the two structures. Moreover, we find distinct distribution patterns of different molecular markers within the parasubiculum, across both superficial-deep and DV axes. Using unsupervised cluster analysis, we find that neurons in the parasubiculum can be broadly separated into three clusters based on their electrophysiological properties, and that each cluster corresponds to a different molecular marker. We demonstrate that, while the parasubiculum aligns structurally to some to general cortical principals, it also shows divergent features in particular in contrast to the MEC. This work will form an important basis for future studies working to disentangle the circuitry underlying memory and spatial navigation functions of the parasubiculum. We identify the major neuron types in the parasubiculum using immunohistochemistry and electrophysiology, and determine their distribution throughout the parasubiculum. We find that the neuronal composition of the parasubiculum differs considerably compared with the neighboring medial entorhinal cortex. Both regions are involved in spatial navigation. Thus, our findings are of importance for unraveling the underlying circuitry of this process and for determining the role of the parasubiculum within this network.
Topics: Animals; Entorhinal Cortex; Female; Hippocampus; Male; Mice; Mice, Inbred C57BL; Neuroanatomical Tract-Tracing Techniques; Neurons; Spatial Navigation
PubMed: 31548233
DOI: 10.1523/JNEUROSCI.0796-19.2019 -
Parkinsonism & Related Disorders Sep 2020Biallelic mutations in PTEN-induced putative kinase 1 (PINK1) is a relatively common cause of autosomal recessive early-onset Parkinson's disease (PD). However, only...
INTRODUCTION
Biallelic mutations in PTEN-induced putative kinase 1 (PINK1) is a relatively common cause of autosomal recessive early-onset Parkinson's disease (PD). However, only three PINK1 patients with brain autopsy have been reported in the literature.
METHODS
We describe the clinical and pathological characteristics of a patient with early-onset PD. We screened for copy number variants SNCA, PRKN, PINK1, DJ-1, ATP13A2, LPA and TNFRSF9 by multiplex ligation-dependent probe amplification (MLPA), and subsequently we performed whole-exome sequencing.
RESULTS
Clinically the patient presented with typical parkinsonism that responded well to levodopa. After 23 years of disease she had a bilateral GPi deep brain stimulation (DBS) surgery. Genetic analyses revealed a heterozygous exon 4-5 deletion and a homozygous exon 1 [c. 230T > C (p.Leu77Pro)] mutation in PINK1. Post-mortem neuropathological examination after more than 30 years of disease revealed gliosis and a large loss of melanin-containing neurons in the substantia nigra. Lewy body pathology was evident in substantia nigra, temporal cortex, locus coeruleus and the parahippocampal region.
CONCLUSION
We describe the first clinical and pathological characterization of a PINK1 patient with a typical disease presentation and long disease duration. Previous reports describe two patients with Lewy-related pathologies, albeit with differential distribution, and one patient with no Lewy-related pathology. Hence, it seems that only two patients with parkinsonism due to mutations in PINK1 are consistent with α-synucleinopathy distribution like that seen in the majority of cases with sporadic PD. Our data further extend the clinicopathological characterization of PINK1-associated PD.
Topics: Aged; Autopsy; Deep Brain Stimulation; Female; Gliosis; Globus Pallidus; Humans; Lewy Bodies; Locus Coeruleus; Parahippocampal Gyrus; Parkinson Disease; Protein Kinases; Substantia Nigra; Temporal Lobe
PubMed: 32814227
DOI: 10.1016/j.parkreldis.2020.07.023 -
NeuroImage Sep 2021Humans use different spatial reference frames (allocentric or egocentric) to navigate successfully toward their destination in different spatial scale spaces... (Review)
Review
Humans use different spatial reference frames (allocentric or egocentric) to navigate successfully toward their destination in different spatial scale spaces (environmental or vista). However, it remains unclear how the brain represents different spatial scales and different spatial reference frames. Thus, we conducted an activation likelihood estimation (ALE) meta-analysis of 47 fMRI articles involving human spatial navigation. We found that both the environmental and vista spaces activated the parahippocampal place area (PPA), retrosplenial complex (RSC), and occipital place area in the right hemisphere. The environmental space showed stronger activation than the vista space in the occipital and frontal regions. No brain region exhibited stronger activation for the vista than the environmental space. The allocentric and egocentric reference frames activated the bilateral PPA and right RSC. The allocentric frame showed more stronger activations than the egocentric frame in the right culmen, left middle frontal gyrus, and precuneus. No brain region displayed stronger activation for the egocentric than the allocentric navigation. Our findings suggest that navigation in different spatial scale spaces can evoke specific and common brain regions, and that the brain regions representing spatial reference frames are not absolutely separated.
Topics: Environment; Humans; Nerve Net; Occipital Lobe; Parahippocampal Gyrus; Space Perception; Spatial Navigation
PubMed: 34129948
DOI: 10.1016/j.neuroimage.2021.118264 -
Journal of Behavioral Addictions Apr 2020Understanding the neural mechanisms underlying Internet gaming disorder (IGD) is essential for the condition's diagnosis and treatment. Nevertheless, the pathological...
OBJECTIVES
Understanding the neural mechanisms underlying Internet gaming disorder (IGD) is essential for the condition's diagnosis and treatment. Nevertheless, the pathological mechanisms of IGD remain elusive at present. Hence, we employed multi-voxel pattern analysis (MVPA) and spectral dynamic causal modeling (spDCM) to explore this issue.
METHODS
Resting-state fMRI data were collected from 103 IGD subjects (male = 57) and 99 well-matched recreational game users (RGUs, male = 51). Regional homogeneity was calculated as the feature for MVPA based on the support vector machine (SVM) with leave-one- out cross-validation. Mean time series data extracted from the brain regions in accordance with the MVPA results were used for further spDCM analysis.
RESULTS
Results display a high accuracy of 82.67% (sensitivity of 83.50% and specificity of 81.82%) in the classification of the two groups. The most discriminative brain regions that contributed to the classification were the bilateral parahippocampal gyrus (PG), right anterior cingulate cortex (ACC), and middle frontal gyrus (MFG). Significant correlations were found between addiction severity (IAT and DSM scores) and the ReHo values of the brain regions that contributed to the classification. Moreover, the results of spDCM showed that compared with RGU, IGD showed decreased effective connectivity from the left PG to the right MFG and from the right PG to the ACC and decreased self-connection in the right PG.
CONCLUSIONS
These results show that the weakening of the PG and its connection with the prefrontal cortex, including the ACC and MFG, may be an underlying mechanism of IGD.
Topics: Adult; Connectome; Female; Gyrus Cinguli; Humans; Internet Addiction Disorder; Magnetic Resonance Imaging; Male; Parahippocampal Gyrus; Prefrontal Cortex; Sensitivity and Specificity; Support Vector Machine; Video Games; Young Adult
PubMed: 32359234
DOI: 10.1556/2006.2020.00012 -
The Journal of Neuroscience : the... Jun 2021The postrhinal area (POR) is a known center for integrating spatial with nonspatial visual information and a possible hub for influencing landmark navigation by...
The postrhinal area (POR) is a known center for integrating spatial with nonspatial visual information and a possible hub for influencing landmark navigation by affective input from the amygdala. This may involve specific circuits within muscarinic acetylcholine receptor 2 (M2)-positive (M2) or M2 modules of POR that associate inputs from the thalamus, cortex, and amygdala, and send outputs to the entorhinal cortex. Using anterograde and retrograde labeling with conventional and viral tracers in male and female mice, we found that all higher visual areas of the ventral cortical stream project to the amygdala, while such inputs are absent from primary visual cortex and dorsal stream areas. Unexpectedly for the presumed salt-and-pepper organization of mouse extrastriate cortex, tracing results show that inputs from the dorsal lateral geniculate nucleus and lateral posterior nucleus were spatially clustered in layer 1 (L1) and overlapped with M2 patches of POR. In contrast, input from the amygdala to L1 of POR terminated in M2 interpatches. Importantly, the amygdalocortical input to M2 interpatches in L1 overlapped preferentially with spatially clustered apical dendrites of POR neurons projecting to amygdala and entorhinal area lateral, medial (ENTm). The results suggest that subnetworks in POR, used to build spatial maps for navigation, do not receive direct thalamocortical M2 patch-targeting inputs. Instead, they involve local networks of M2 interpatches, which are influenced by affective information from the amygdala and project to ENTm, whose cells respond to visual landmark cues for navigation. A central purpose of visual object recognition is identifying the salience of objects and approaching or avoiding them. However, it is not currently known how the visual cortex integrates the multiple streams of information, including affective and navigational cues, which are required to accomplish this task. We find that in a higher visual area, the postrhinal cortex, the cortical sheet is divided into interdigitating modules receiving distinct inputs from visual and emotion-related sources. One of these modules is preferentially connected with the amygdala and provides outputs to entorhinal cortex, constituting a processing stream that may assign emotional salience to objects and landmarks for the guidance of goal-directed navigation.
Topics: Amygdala; Animals; Entorhinal Cortex; Female; Male; Mice; Mice, Inbred C57BL; Neural Pathways; Spatial Navigation; Visual Cortex
PubMed: 33849948
DOI: 10.1523/JNEUROSCI.2185-20.2021 -
Brain and Behavior May 2021Pathological abnormalities first appear in the medial temporal regions including entorhinal cortex and parahippocampus in patients with Alzheimer's disease. Previous...
INTRODUCTION
Pathological abnormalities first appear in the medial temporal regions including entorhinal cortex and parahippocampus in patients with Alzheimer's disease. Previous studies showed that olfactory decline in elderly subjects was associated with volume reductions in the left hippocampus and left parahippocampus without cognitive impairment. The aim of this study is to investigate the link between olfaction and volume reductions in the medial temporal regions including the parahippocampus, entorhinal cortex, and hippocampal subfields.
METHOD
27 elderly subjects and 27 young controls were measured olfaction acuity, cognitive function, and structural magnetic resonance imaging. Image processing and gray matter volumetric segmentation were performed with FreeSurfer. Volume data were analyzed with SPSS Statistics software.
RESULTS
Interesting results of this study were that volume reduction in the entorhinal cortex was not directly linked with declining olfactory ability. Volume reduction in the left entorhinal cortex was correlated with volume reduction in the left parahippocampus and dentate gyrus. However, left parahippocampus volume reduction had the greatest impact on olfactory decline, and the entorhinal cortex and dentate gyrus might additionally contribute to olfactory decline.
CONCLUSION
Our results indicate that olfactory decline may be directly reflected in the medial temporal regions as reduced parahippocampus volumes, rather than as morphological changes in the entorhinal cortex and hippocampus. The parahippocampus may play an important role in the association between memory retrieval and olfactory identification.
Topics: Aged; Entorhinal Cortex; Hippocampus; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Smell
PubMed: 33769719
DOI: 10.1002/brb3.2115 -
Ideggyogyaszati Szemle Sep 2020Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of... (Review)
Review
Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called "Brain GPS". The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.
Topics: Entorhinal Cortex; Hippocampus; Humans; Memory; Neurosciences; Spatial Navigation
PubMed: 33035420
DOI: 10.18071/isz.73.0295 -
Cell Reports Apr 2024Understanding how emotional processing modulates learning and memory is crucial for the treatment of neuropsychiatric disorders characterized by emotional memory...
Understanding how emotional processing modulates learning and memory is crucial for the treatment of neuropsychiatric disorders characterized by emotional memory dysfunction. We investigate how human medial temporal lobe (MTL) neurons support emotional memory by recording spiking activity from the hippocampus, amygdala, and entorhinal cortex during encoding and recognition sessions of an emotional memory task in patients with pharmaco-resistant epilepsy. Our findings reveal distinct representations for both remembered compared to forgotten and emotional compared to neutral scenes in single units and MTL population spiking activity. Additionally, we demonstrate that a distributed network of human MTL neurons exhibiting mixed selectivity on a single-unit level collectively processes emotion and memory as a network, with a small percentage of neurons responding conjointly to emotion and memory. Analyzing spiking activity enables a detailed understanding of the neurophysiological mechanisms underlying emotional memory and could provide insights into how emotion alters memory during healthy and maladaptive learning.
Topics: Humans; Emotions; Neurons; Memory; Male; Adult; Female; Temporal Lobe; Amygdala; Entorhinal Cortex; Hippocampus; Young Adult
PubMed: 38592973
DOI: 10.1016/j.celrep.2024.114071 -
Acta Neuropathologica Communications Jul 2021The medial temporal lobe (MTL) is a nidus for neurodegenerative pathologies and therefore an important region in which to study polypathology. We investigated...
The medial temporal lobe (MTL) is a nidus for neurodegenerative pathologies and therefore an important region in which to study polypathology. We investigated associations between neurodegenerative pathologies and the thickness of different MTL subregions measured using high-resolution post-mortem MRI. Tau, TAR DNA-binding protein 43 (TDP-43), amyloid-β and α-synuclein pathology were rated on a scale of 0 (absent)-3 (severe) in the hippocampus and entorhinal cortex (ERC) of 58 individuals with and without neurodegenerative diseases (median age 75.0 years, 60.3% male). Thickness measurements in ERC, Brodmann Area (BA) 35 and 36, parahippocampal cortex, subiculum, cornu ammonis (CA)1 and the stratum radiatum lacunosum moleculare (SRLM) were derived from 0.2 × 0.2 × 0.2 mm post-mortem MRI scans of excised MTL specimens from the contralateral hemisphere using a semi-automated approach. Spearman's rank correlations were performed between neurodegenerative pathologies and thickness, correcting for age, sex and hemisphere, including all four proteinopathies in the model. We found significant associations of (1) TDP-43 with thickness in all subregions (r = - 0.27 to r = - 0.46), and (2) tau with BA35 (r = - 0.31) and SRLM thickness (r = - 0.33). In amyloid-β and TDP-43 negative cases, we found strong significant associations of tau with ERC (r = - 0.40), BA35 (r = - 0.55), subiculum (r = - 0.42) and CA1 thickness (r = - 0.47). This unique dataset shows widespread MTL atrophy in relation to TDP-43 pathology and atrophy in regions affected early in Braak stageing and tau pathology. Moreover, the strong association of tau with thickness in early Braak regions in the absence of amyloid-β suggests a role of Primary Age-Related Tauopathy in neurodegeneration.
Topics: Adult; Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Peptides; Brain Cortical Thickness; CA1 Region, Hippocampal; Case-Control Studies; DNA-Binding Proteins; Entorhinal Cortex; Female; Frontotemporal Lobar Degeneration; Hippocampus; Humans; Lewy Body Disease; Magnetic Resonance Imaging; Male; Middle Aged; Neurodegenerative Diseases; Neurofibrillary Tangles; Parahippocampal Gyrus; Pick Disease of the Brain; Plaque, Amyloid; Supranuclear Palsy, Progressive; Temporal Lobe; alpha-Synuclein; tau Proteins
PubMed: 34289895
DOI: 10.1186/s40478-021-01225-3