The neostriatum: two entities, one structure?

Proceedings of the National Academy of Sciences, 1998

Histological sections of the mammalian striatum reveal a “matrix” that is histochemically distinguishable from patches, or “striosomes”. The latter are cross sections of a compartment that consists primarily of tube-shaped structures radiating through the matrix. As a test of the hypothesis that the function of the striosome/patch compartment includes the mediation of behaviors related to reward, the present study examined electrical self-stimulation of the caudoputamen in rats with electrodes in either of the two compartments. Rats acquired and maintained bar-pressing responses that were contingent on stimulation through electrodes making contact with striosomes/patches more reliably than animals with electrodes terminating exclusively in the matrix. The results provide in vivo evidence that the striosome/patch compartment is functionally differentiated from the matrix compartment: Stimulation centered in or around the striosome/patch compartment but not in the matrix led to rapid ...

Neuron, 2016

The striatum contains neurochemically defined compartments termed patches and matrix. Previous studies suggest patches preferentially receive limbic inputs and project to dopamine neurons in substantia nigra pars compacta (SNc), whereas matrix neurons receive sensorimotor inputs and do not innervate SNc. Using BAC-Cre transgenic mice with viral tracing techniques, we mapped brain-wide differences in the input-output organization of the patch/matrix. Findings reveal a displaced population of striatal patch neurons termed "exo-patch," which reside in matrix zones but have neurochemistry, connectivity, and electrophysiological characteristics resembling patch neurons. Contrary to previous studies, results show patch/exo-patch and matrix neurons receive both limbic and sensorimotor information. A novel inhibitory projection from bed nucleus of the stria terminalis to patch/exo-patch neurons was revealed. Projections to SNc were found to originate from patch/exo-patch and matri...

Frontiers in neuroanatomy, 2017

The striatum is key for action-selection and the motivation to move. Dopamine and acetylcholine release sites are enriched in the striatum and are cross-regulated, possibly to achieve optimal behavior. Drugs of abuse, which promote abnormally high dopamine release, disrupt normal action-selection and drive restricted, repetitive behaviors (stereotypies). Stereotypies occur in a variety of disorders including obsessive-compulsive disorder, autism, schizophrenia and Huntington's disease, as well as in addictive states. The severity of drug-induced stereotypy is correlated with induction of c-Fos expression in striosomes, a striatal compartment that is related to the limbic system and that directly projects to dopamine-producing neurons of the substantia nigra. These characteristics of striosomes contrast with the properties of the extra-striosomal matrix, which has strong sensorimotor and associative circuit inputs and outputs. Disruption of acetylcholine signaling in the striatum...

Proceedings of the National Academy of Sciences, 2016

The dopamine systems of the brain powerfully influence movement and motivation. We demonstrate that striatonigral fibers originating in striosomes form highly unusual bouquet-like arborizations that target bundles of ventrally extending dopamine-containing dendrites and clusters of their parent nigral cell bodies. Retrograde tracing showed that these clustered cell bodies in turn project to the striatum as part of the classic nigrostriatal pathway. Thus, these striosome–dendron formations, here termed “striosome–dendron bouquets,” likely represent subsystems with the nigro–striato–nigral loop that are affected in human disorders including Parkinson’s disease. Within the bouquets, expansion microscopy resolved many individual striosomal fibers tightly intertwined with the dopamine-containing dendrites and also with afferents labeled by glutamatergic, GABAergic, and cholinergic markers and markers for astrocytic cells and fibers and connexin 43 puncta. We suggest that the striosome–de...

Journal of Neuroscience, 2009

Recent studies have demonstrated that GABAergic synaptic transmission among neostriatal spiny projection neurons (SPNs)is strongly modulated by dopamine with individual connections exhibiting either D 1 receptor (D 1 R)-mediated facilitation or D 2 receptor (D 2 R)-mediated inhibition and, at least in some preparations, a subset of connections exhibiting both of these effects. In light of the cell typespecific expression of D 1a R in striatonigral and D 2 R in striatopallidal neurons and the differential expression of the other D 1 and D 2 family dopamine receptors, we hypothesize that the nature of the dopaminergic modulation is specific to the types of SPNs that participate in the connection. Here the biophysical properties and dopaminergic modulation of intrastriatal connections formed by striatopallidal neurons were examined. Contrary to previous expectation, synapses formed by striatopallidal neurons were biophysically and pharmacologically heterogeneous. Two distinct types of axon collateral connections could be distinguished among striatopallidal neurons. The more common, small-amplitude connections (80%) exhibited mean IPSC amplitudes several times smaller than their less frequent large-amplitude counterparts, principally because of a smaller number of release sites involved. The two types of connections were also differentially regulated by dopamine. Small-amplitude connections exhibited strong and exclusively D 2 R-mediated presynaptic inhibition, whereas large-amplitude connections were unresponsive to dopamine. Synaptic connections from striatopallidal to striatonigral neurons exhibited exclusively D 2 R-mediated presynaptic inhibition that was similar to the regulation of small-amplitude connections between pairs of striatopallidal cells. Together, these findings demonstrate a previously unrecognized complexity in the organization and dopaminergic control of synaptic communication among SPNs.

Proceedings of the National Academy of Sciences, 2010

The direct and indirect pathways of the basal ganglia have been proposed to oppositely regulate locomotion and differentially contribute to pathological behaviors. Analysis of the distinct contributions of each pathway to behavior has been a challenge, however, due to the difficulty of selectively investigating the neurons comprising the two pathways using conventional techniques. Here we present two mouse models in which the function of striatonigral or striatopallidal neurons is selectively disrupted due to cell typespecific deletion of the striatal signaling protein dopamine-and cAMP-regulated phosphoprotein Mr 32kDa (DARPP-32). Using these mice, we found that the loss of DARPP-32 in striatonigral neurons decreased basal and cocaine-induced locomotion and abolished dyskinetic behaviors in response to the Parkinson's disease drug L-DOPA. Conversely, the loss of DARPP-32 in striatopallidal neurons produced a robust increase in locomotor activity and a strongly reduced cataleptic response to the antipsychotic drug haloperidol. These findings provide insight into the selective contributions of the direct and indirect pathways to striatal motor behaviors.

Trends in Neurosciences, 2003

Frontiers in Behavioral Neuroscience, 2015

The striatum serves as the main input to the basal ganglia, and is key for the regulation of motor behaviors, compulsion, addiction, and various cognitive and emotional states. Its deterioration is associated with degenerative disorders such as Huntington's disease. Despite its apparent anatomical uniformity, it consists of intermingled cell populations, which have precluded straightforward anatomical sub-classifications adhering to functional dissections. Approximately 95% of the striatal neurons are inhibitory projection neurons termed medium spiny neurons (MSNs). They are commonly classified according to their expression of either dopamine receptor D1 or D2, which also determines their axonal projection patterns constituting the direct and indirect pathway in the basal ganglia. Immunohistochemical patterns have further indicated compartmentalization of the striatum to the striosomes and the surrounding matrix, which integrate MSNs of both the D1 and D2 type. Here, we present a transgenic mouse line, Gpr101-Cre, with Cre recombinase activity localized to matrix D1 and D2 MSNs. Using two Gpr101-Cre founder lines with different degrees of expression in the striatum, we conditionally deleted the vesicular inhibitory amino acid transporter (VIAAT), responsible for storage of GABA and glycine in synaptic vesicles. Partial ablation of VIAAT (in ∼36% of MSNs) resulted in elevated locomotor activity compared to control mice, when provoked with the monoamine reuptake inhibitor cocaine. Near complete targeting of matrix MSNs led to profoundly changed motor behaviors, which increased in severity as the mice aged. Moreover, these mice had exaggerated muscle rigidity, retarded growth, increased rate of spontaneous deaths, and defective memory. Therefore, our data provide a link between dysfunctional GABA signaling of matrix MSNs to specific behavioral alterations, which are similar to the symptoms of Huntington's disease.

Progress in Neurobiology, 2000

Striatal neurones receive myriad of synaptic inputs originating from dierent sources. Massive aerents from all areas of the cortex and the thalamus represent the most important source of excitatory amino acids, whereas the nigrostriatal pathway and intrinsic circuits provide the striatum with dopamine, acetylcholine, GABA, nitric oxide and adenosine. All these neurotransmitter systems interact each other and with voltage-dependent conductances to regulate the ecacy of the synaptic transmission within this nucleus. The integrative action exerted by striatal projection neurones on this converging information dictates the ®nal output of the striatum to the other basal ganglia structures. Recent morphological, immunohistochemical and electrophysiological ®ndings demonstrated that the striatum also contains dierent interneurones, whose role in physiological and pathological conditions represents an intriguing challenge in these years. The use of the in vitro brain slice preparation has allowed not only the detailed investigation of the direct pre-and postsynaptic electrophysiological actions of several neurotransmitters in striatal neurones, but also the understanding of their role in two dierent forms of corticostriatal synaptic plasticity, long-term depression and long-term potentiation. These long-lasting changes in the ecacy of excitatory transmission have been proposed to represent the cellular basis of some forms of motor learning and are altered in animal models of human basal ganglia disorders, such as Parkinson's disease. The striatum also expresses high sensitivity to hypoxic±aglycemic insults. During these pathological conditions, striatal synaptic transmission is altered depending on presynaptic inhibition of transmitter release and opposite membrane potential changes occur in projection neurones and in cholinergic interneurones. These ionic Progress in Neurobiology 61 0301-0082/00/$ -see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S 0 3 0 1 -0 0 8 2 ( 9 9 ) 0 0 0 3 0 -1

Journal of Neuroscience, 2004

The two main types of corticostriatal neurons are those that project only intratelencephalically (IT-type), the intrastriatal terminals of which are 0.41 m in mean diameter, and those that send their main axon into pyramidal tract and have a collateral projection to striatum (PT-type), the intrastriatal terminals of which are 0.82 m in mean diameter. We used three approaches to examine whether the two striatal projection neuron types (striatonigral direct pathway vs striatopallidal indirect pathway) differ in their input from IT-type and PT-type neurons. First, we retrogradely labeled one striatal projection neuron type or the other with biotinylated dextran amine (BDA)-3000 molecular weight. We found that terminals making asymmetric axospinous contact with striatonigral neurons were 0.43 m in mean diameter, whereas those making asymmetric axospinous contact with striatopallidal neurons were 0.69 m. Second, we preferentially immunolabeled striatonigral neurons for D 1 dopamine receptors or striatopallidal neurons for D 2 dopamine receptors and found that axospinous terminals had a smaller mean size (0.45 m) on D 1 ϩ spines than on D 2 ϩ spines (0.61 m). Finally, we combined selective BDA labeling of IT-type or PT-type terminals with immunolabeling for D 1 or D 2 , and found that IT-type terminals were twice as common as PT-type on D 1 ϩ spines, whereas PT-type terminals were four times as common as IT-type on D 2 ϩ spines. These various results suggest that striatonigral neurons preferentially receive input from IT-type cortical neurons, whereas striatopallidal neurons receive greater input from PT-type cortical neurons. This differential cortical connectivity may further the roles of the direct and indirect pathways in promoting desired movements and suppressing unwanted movements, respectively.