Dataset Information

Striatal and medial temporal lobe functional interactions during visuomotor associative learning.

ABSTRACT: A network of regions including the medial temporal lobe (MTL) and the striatum are integral to visuomotor associative learning. Here, we evaluated the contributions of the structures of the striatum and the MTL, as well as their interactions during an arbitrary associative learning task. We hypothesized that activity in the striatum would correlate with the rate of learning, while activity in the MTL would track how well associations were learned. Further, we expected functional correlations to show both facilitative as well as competitive relationships depending on the regions involved. Results showed that activity throughout the striatum was modulated by the rate of learning, while the sensorimotor and ventral striatum were also modulated by probability correct. Across the MTL, activity correlated with the probability of being correct, while the perirhinal cortex and right parahippocampal cortex were modulated by the rate of learning. The activity in the ventral striatum robustly coupled with activity in the MTL during learning, while interactions between the associative striatum and the MTL showed the opposite pattern. These findings suggest dissociable computational roles for different subregions of the striatum and MTL. These subregions interact in distinct ways, perhaps forming functionally integrated networks during the learning of arbitrary associations.

SUBMITTER: Mattfeld AT

PROVIDER: S-EPMC3297014 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature

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Striatal and medial temporal lobe functional interactions during visuomotor associative learning.

Mattfeld Aaron T AT Stark Craig E L CE

Cerebral cortex (New York, N.Y. : 1991) 20100805 3

A network of regions including the medial temporal lobe (MTL) and the striatum are integral to visuomotor associative learning. Here, we evaluated the contributions of the structures of the striatum and the MTL, as well as their interactions during an arbitrary associative learning task. We hypothesized that activity in the striatum would correlate with the rate of learning, while activity in the MTL would track how well associations were learned. Further, we expected functional correlations to ...[more]

PMID: 20688877

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Project description:This study examined whether longitudinal MRI trajectories in medial temporal lobe (MTL) brain regions differed among groups of cognitively normal individuals defined by their cerebrospinal fluid (CSF) levels when they were first enrolled (N = 207; mean clinical follow-up = 13.3 years (max = 20 years), mean MRI follow-up = 2.4 years (max = 8 years)). We first compared atrophy rates among groups defined by CSF amyloid and phosphorylated-tau (p-tau) vs. CSF amyloid and total tau (t-tau). We also examined whether, in the presence of amyloid or tau/p-tau, the atrophy rates differed based on whether the subjects ultimately progressed to a diagnosis of mild cognitive impairment (MCI), as well as whether apolipoprotein ?4 (Apo?4) status had an impact on the longitudinal MRI trajectories. The primary finding was that when the groups were defined using CSF amyloid and p-tau, individuals with low levels of CSF amyloid and high levels of CSF p-tau (referred to as Stage 2) showed a significantly greater rate of atrophy in a composite measure of MTL volumes compared to groups defined by evidence of abnormal CSF levels in only one of the brain proteins (but not both), or no evidence of CSF abnormality. In contrast, there were no differences in rate of MTL atrophy when the groups were defined by levels of CSF amyloid and t-tau (instead of p-tau). Additionally, the rate of MTL atrophy did not differ between subjects who progressed to MCI at follow-up vs. those who remained cognitively normal when CSF levels of amyloid, t-tau, or p-tau were covaried. Lastly, the presence of an APOE ?4 genotype did not modulate the degree of MTL atrophy once baseline levels of CSF amyloid, p-tau or t-tau were accounted for. These results suggest that abnormal levels of CSF amyloid and CSF p-tau (but not t-tau) maximize the likelihood of observing significant MTL atrophy over time among individuals with normal cognition at baseline, and emphasize the importance of differentiating biomarkers that primarily reflect neurofibrillary tangle pathology (CSF p-tau) compared with biomarkers of neuronal injury (CSF t-tau).

Project description:BackgroundMedial temporal lobe epilepsy (MTLE) is associated with limbic atrophy involving the hippocampus, peri-hippocampal and extra-temporal structures. While MTLE is related to static structural limbic compromise, it is unknown whether the limbic system undergoes dynamic regional perfusion network alterations during seizures. In this study, we aimed to investigate state specific (i.e. ictal versus interictal) perfusional limbic networks in patients with MTLE.MethodsWe studied clinical information and single photon emission computed tomography (SPECT) images obtained with intravenous infusion of the radioactive tracer Technetium- Tc 99 m Hexamethylpropyleneamine Oxime (Tc-99 m HMPAO) during ictal and interictal state confirmed by video-electroencephalography (VEEG) in 20 patients with unilateral MTLE (12 left and 8 right MTLE). Pair-wise voxel-based analyses were used to define global changes in tracer between states. Regional tracer uptake was calculated and state specific adjacency matrices were constructed based on regional correlation of uptake across subjects. Graph theoretical measures were applied to investigate global and regional state specific network reconfigurations.ResultsA significant increase in tracer uptake was observed during the ictal state in the medial temporal region, cerebellum, thalamus, insula and putamen. From network analyses, we observed a relative decreased correlation between the epileptogenic temporal region and remaining cortex during the interictal state, followed by a surge of cross-correlated perfusion in epileptogenic temporal-limbic structures during a seizure, corresponding to local network integration.ConclusionsThese results suggest that MTLE is associated with a state specific perfusion and possibly functional organization consisting of a surge of limbic cross-correlated tracer uptake during a seizure, with a relative disconnection of the epileptogenic temporal lobe in the interictal period. This pattern of state specific shift in metabolic networks in MTLE may improve the understanding of epileptogenesis and neuropsychological impairments associated with MTLE.

Dataset Information

Striatal and medial temporal lobe functional interactions during visuomotor associative learning.

Publications

Striatal and medial temporal lobe functional interactions during visuomotor associative learning.

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