Topographic involvement of the striatal efferents in basal ganglia of patients with adult-onset motor neuron disease with basophilic inclusions

Beyond and below the cortex: the contribution of striatal dysfunction to cognition and behaviour in neurodegeneration

Investigations of cognitive and behavioural changes in neurodegeneration have been mostly focussed on how cortical changes can explain these symptoms. In the proposed review, we will argue that the striatum has been overlooked as a critical nexus in understanding the generation of such symptoms. Although the striatum is historically more associated with motor dysfunction, there is increasing evidence from functional neuroimaging studies in the healthy that striatal regions modulate behaviour and cognition. This should not be surprising, as the striatum has strong anatomical connections to many cortical regions including the frontal, temporal and insula lobes, as well as some subcortical regions (amygdala, hippocampus). To date, however, it is largely unclear to what extent striatal regions are affected in many neurodegenerative conditions-and if so, how striatal dysfunction can potentially influence cognition and behaviour. The proposed review will examine the existing evidence of striatal changes across selected neurodegenerative conditions (Parkinson's disease, progressive supranuclear palsy, Huntington's disease, motor neuron disease, frontotemporal dementia and Alzheimer's disease), and will document their link with the cognitive and behavioural impairments observed. Thus, by reviewing the varying degrees of cortical and striatal changes in these conditions, we can start outlining the contributions of the striatal nexus to cognitive and behavioural symptoms. In turn, this knowledge will inform future studies investigating corticostriatal networks and also diagnostic strategies, disease management and future therapeutics of neurodegenerative conditions.

Familial ALS with FUS P525L mutation: two Japanese sisters with multiple systems involvement

We evaluated the clinicopathological features of familial amyotrophic lateral sclerosis (ALS) with the fused in sarcoma (FUS) P525L mutation. Two sisters and their mother had a similar clinical course, which was characterized by the development of limb weakness at a young age with rapid disease progression. An elder sister, patient 1, progressed into a totally locked-in state requiring mechanical ventilation and died 26 years after the onset of the disease. In contrast, the younger sister, patient 2, died in the early stages of the disease. The patients had neuropathological findings that indicated a very active degeneration of motor neurons and multiple system degeneration, which led to marked brain and spinal cord atrophy in the long term clinical outcome. The multiple system degeneration included the frontal lobe, the basal ganglia and substantia nigra, cerebellum and related area. Compared with previously reported ALS cases, the severe degeneration of the frontal lobe and the striatum were the characteristic features in the patient 1 in this case study. The degeneration spread over multiple systems might be caused not only by the appearance of the FUS immunoreactive neuronal cytoplasmic inclusions but also by the degeneration of neuronal connections from the primary motor cortex and related areas.

Young-onset sporadic amyotrophic lateral sclerosis: a distinct nosological entity?

There are few reports describing young-onset amyotrophic lateral sclerosis (ALS). Age at onset is a prognostic factor in ALS, and thus it is relevant to investigate the clinical features of very young ALS patients. We describe three young-onset ALS cases and review the literature. SOD1 mutations were not identified. Our cases and 24 others from the literature indicate that young-onset ALS is characterized by slowly progressive symmetrical weakness; nevertheless, progression is variable. Young-onset ALS seems to be a distinct clinical syndrome but its aetiological background is largely unknown.

Differential synaptology of vGluT2-containing thalamostriatal afferents between the patch and matrix compartments in rats

The striatum is divided into two compartments named the patch (or striosome) and the matrix. Although these two compartments can be differentiated by their neurochemical content or afferent and efferent projections, the synaptology of inputs to these striatal regions remains poorly characterized. By using the vesicular glutamate transporters vGluT1 and vGluT2, as markers of corticostriatal and thalamostriatal projections, respectively, we demonstrate a differential pattern of synaptic connections of these two pathways between the patch and the matrix compartments. We also demonstrate that the majority of vGluT2-immunolabeled axon terminals form axospinous synapses, suggesting that thalamic afferents, like corticostriatal inputs, terminate preferentially onto spines in the striatum. Within both compartments, more than 90% of vGluT1-containing terminals formed axospinous synapses, whereas 87% of vGluT2-positive terminals within the patch innervated dendritic spines, but only 55% did so in the matrix. To characterize further the source of thalamic inputs that could account for the increase in axodendritic synapses in the matrix, we undertook an electron microscopic analysis of the synaptology of thalamostriatal afferents to the matrix compartments from specific intralaminar, midline, relay, and associative thalamic nuclei in rats. Approximately 95% of PHA-L-labeled terminals from the central lateral, midline, mediodorsal, lateral dorsal, anteroventral, and ventral anterior/ventral lateral nuclei formed axospinous synapses, a pattern reminiscent of corticostriatal afferents but strikingly different from thalamostriatal projections arising from the parafascicular nucleus (PF), which terminated onto dendritic shafts. These findings provide the first evidence for a differential pattern of synaptic organization of thalamostriatal glutamatergic inputs to the patch and matrix compartments. Furthermore, they demonstrate that the PF is the sole source of significant axodendritic thalamic inputs to striatal projection neurons. These observations pave the way for understanding differential regulatory mechanisms of striatal outflow from the patch and matrix compartments by thalamostriatal afferents.

The ultrastructural organization of the patch matrix compartments in the human striatum

The mammalian striatum is a heterogeneous structure characterized by striosomes and matrix. The synaptic organization of the striatum has been described previously in various mammalian species including human; however, potential ultrastructural differences in striosomal organization have not been well studied. Samples (n = 7) of striatal tissue were obtained from the Maryland Brain Collection (mean age, 37.7 +/- 9.4 years; and mean PMI, 5.3 +/- 1.4 hours). Tissue was prepared for calbindin immunocytochemistry to identify striosomal (patch) and extrastriosomal matrix (matrix) compartments and subsequently prepared for electron microscopy. Synaptic density was determined, using stereologic methods, for all synapses combined and for various subsets of synapses such as asymmetric, symmetric, axospinous, axodendritic, and perforated in the patch and matrix of the caudate (CP, CM) and putamen (PP, PM). An ANOVA revealed significant between-group (CP, CM, PP, PM) differences (P < 0.05) for the following types of synapses: total combined, asymmetric, axospinous, and asymmetric axospinous. Each of these four types was significantly increased in density in the CP vs the PP, whereas the matrix (CM vs PM) showed no significant differences in density in these or other synapses. In the caudate (CP vs CM), the synaptic density of the types of synapses studied did not vary significantly between the patch and the matrix. In the putamen, the matrix (PM) had higher synaptic densities than that of the patches (PP) for total synapses, symmetric dendritic, and perforated. These data show that the patch and matrix compartments are heterogeneous at the ultrastructural level, imparting another level of complexity to the striatum-a fact that should be taken into consideration when studying diseases of this brain region at the electron microscopic level.