Striatum

Cross references:   Ventral Striatum    Locomotion Sequence Revision   
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Kolb and Whishaw don't mention either a "striatum" or a "corpus striatum", but this may just indicate that these are just older terms for what is now called the "basal ganglia".   K&W do discuss the basal ganglia in several places, with pictures.  [K&W: 55-58, 375-377 & 502-510]. 


Striatum (Wiki) 
    "
Brain: Striatum
BrainCaudatePutamen.svg
purple=caudate and putamen, orange=thalamus
Gray741.png
Two views of a model of the striatum. A: lateral aspect, B: medial aspect. (The lenticular nucleus is an alternative name for the putamen and globus pallidus.)


    The striatum, also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain and a critical component of the reward system. It receives glutamatergic and dopaminergic inputs from different sources and serves as the primary input to the basal ganglia system.  

   In all primates, the dorsal striatum is divided by a white matter tract called the internal capsule into two sectors called the caudate nucleus and the putamen.[4] The ventral striatum is composed of the nucleus accumbens and olfactory tubercle in primates.[4]

Contents




Paleostriatum | definition of paleostriatum by Medical dictionary    
http://medical-dictionary.thefreedictionary.com/paleostriatum    

    "Term denoting the globus pallidus and expressing the hypothesis that this component of the striate body developed earlier in evolution than the "neostriatum" or striatum (caudate nucleus and putamen) and that it is a diencephalic derivative. 
    See also: globus pallidus. [paleo- + L. striatum]"


Neostriatum | definition of neostriatum by Medical dictionary
http://medical-dictionary.thefreedictionary.com/neostriatum  

    "The caudate nucleus and putamen considered as one and distinguished from the globus pallidus (paleostriatum). "


1988 10<13
Synaptic organization of the striatum   
http://www.ncbi.nlm.nih.gov/pubmed/3069970   
    "The striatum, the main component of the basal ganglia, is composed of mainly one type of neuron, the so-called medium spiny neuron. This neuron cell type, which constitutes over 90% of striatal neurons, is the major output neuron of the striatum.  Combined ultrastructural neuroanatomical methods have elucidated the organization of afferent connectivity to these neurons.  
    The major physiologic function of striatal efferent activity appears to be inhibition of tonically active GABAergic neurons in the globus pallidus and substantia nigra pars reticulata."   
    See:  Medium Spiny Neurons  ,  Basal Ganglia  and Tonic Inhibition .  


1997    

Organization of the lamprey striatum - transmitters and projections. 
http://www.ncbi.nlm.nih.gov/pubmed/9359610    
    "
Cells immunoreactive for GABA and substance P (SP), and positive for acetylcholinesterase, are present in the lamprey striatum.  
     Immunoreactive (ir) fibers were detected by antisera raised against SP, dopamine, enkephalin and serotonin. These immunoreactive fibers were mainly located in the periventricular neuropil that borders the striatum and in which GABAergic striatal neurons distributed their dendritic arbors.  
    Putative connections between the striatum, the ventral part of the lateral pallium, and the diencephalic motor centers involved in the control of locomotion were studied by using fluorescein-coupled dextran amines (FDA) as a tracer. The striatum projects to the ventral part of the lateral pallium (lpv), where GABA-ir cells and SP-ir fibers were also present. The lpv in turn projects to the ventral thalamus, which has descending connections to the reticulospinal cells involved in the control of locomotion.  
    These results, together with previous findings of histaminergic and neurotensin projections, suggest that the lamprey striatum and its inputs with regard to neurotransmitters/modulators are very similar to those of modem amniotes, including primates, and are thus conserved to a high degree"  


2005

Connectivity and cytoarchitecture of the ventral telencephalon in the salamander Plethodon shermani.
   
http://www.ncbi.nlm.nih.gov/pubmed/15611991  
    "
According to our results, the amygdala of Plethodon is divided into  
    (1) a rostral part projecting to visceral and limbic centers and receiving afferents from the dorsal thalamus, and  
    (2) a caudal part receiving accessory olfactory input.  The striatopallial transition area (SPTA) lies rostrodorsally to the caudal (vomeronasal) amygdala and is similar in connections and possibly in function.  
    The rostral striatum has few descending projections to the medulla, whereas the intermediate striatum sends strong projections to the tegmentum and medulla. The caudal striatum has strong ascending projections to the striatum and descending projections to the ventral hypothalamus. ... It is concluded that, hodologically, the rostral part of the urodele amygdala corresponds to the central and basolateral amygdala and the caudal part to the cortical/medial amygdala of mammals. The urodele striatum is divided into a rostral striatum proper, an intermediate dorsal pallidum, and a caudal part, with distinct connections described here for the first time in a vertebrate."      


2010    
Developmental regulation and neuroprotective effects of striatal tonic GABAA currents. 
http://www.ncbi.nlm.nih.gov/pubmed/20206233  
    "Striatal neurons are known to express GABA(A) receptor subunits that underlie both phasic and tonic inhibition. Striatal projection neurons, or medium spiny neurons (MSNs), are divided into two classes: MSNs containing the dopamine D1 receptor (D1-MSNs) form the direct pathway to the substantia nigra and facilitate movement while MSNs expressing the dopamine D2 receptor (D2-MSNs) form the pallidal pathway that inhibits movement. Consequently, modulating inhibition in distinct classes of MSNs will differentially impact downstream network activity and motor behavior. Given the powerful role of extrasynaptic inhibition in controlling neuronal excitability, we examined the nature of striatal tonic inhibition and its potential role in preventing excitotoxicity. Consistent with earlier studies in young (P16-P25) mice, tonic GABA currents in D2-MSNs were larger than in D1-MSNs. However, with age (>P30 mice) the tonic GABA currents increased in D1-MSNs but decreased in D2-MSNs. These data demonstrate a developmental switch in the MSN subtype expressing larger tonic GABA currents. Compared to wild-type, MSNs from adult mice lacking the GABA(A)R delta subunit (Gabrd(-/-) mice) had both decreased tonic GABA currents and reduced survival following an in vitro excitotoxic challenge with quinolinic acid. Furthermore, muscimol-induced tonic GABA currents were accompanied by reduced acute swelling of striatal neurons after exposure to NMDA in WT mice but not in Gabrd(-/-) mice. Our data are consistent with a role for tonic inhibition mediated by GABA(A)R delta subunits in neuroprotection against excitotoxic insults in the adult striatum."  
    150 Related citations: 
    27 Cited by's: 
Abstract: 
    "
The intrastriatal microcircuit is a predominantly inhibitory GABAergic network comprised of a majority of projection neurons [medium spiny neurons (MSNs)] and a minority of interneurons. The connectivity within this microcircuit is divided into two main categories: lateral connectivity between MSNs, and inhibition mediated by interneurons, in particular fast spiking (FS) cells. To understand the operation of striatum, it is essential to have a good description of the dynamic properties of these respective pathways and how they affect different types of striatal projection neurons. We recorded from neuronal pairs, triplets, and quadruplets in slices of rat and mouse striatum and analyzed the dynamics of synaptic transmission between MSNs and FS cells. Retrograde fluorescent labeling and transgenic EGFP (enhanced green fluorescent protein) mice were used to distinguish between MSNs of the direct (striatonigral) and indirect (striatopallidal) pathways. Presynaptic neurons were stimulated with trains of action potentials, and activity-dependent depression and facilitation of synaptic efficacy was recorded from postsynaptic neurons. We found that FS cells provide a strong and homogeneously depressing inhibition of both striatonigral and striatopallidal MSN types. Moreover, individual FS cells are connected to MSNs of both types. In contrast, both MSN types receive sparse and variable, depressing and facilitating synaptic transmission from nearby MSNs. The connection probability was higher for pairs with presynaptic striatopallidal MSNs; however, the variability in synaptic dynamics did not depend on the types of interconnected MSNs. The differences between the two inhibitory pathways were clear in both species and at different developmental stages. Our findings show that the two intrastriatal inhibitory pathways have fundamentally different dynamic properties that are, however, similarly applied to both direct and indirect striatal projections."      
    Free Article   


2011
Striatal cellular properties conserved from lampreys to mammals.
http://www.ncbi.nlm.nih.gov/pubmed/21502291    
    - Free PMC Article -    
    "
The striatum of the lamprey, the first vertebrate group to appear in evolution, shows striking similarities to that of mammals with respect to histochemical markers, afferent and efferent projections and the effect of dopamine depletion, which leads to hypokinetic motor symptoms.  
    The cellular properties of lamprey striatal neurons were studied here using patch-clamp recordings in acute striatal slices.  
    Sixty-five per cent of recorded neurons were characterised by a prominent inward rectification due to a K+ conductance of the Kir type. They had a ramping response with a long delay to the first action potential due to activation of a low-voltage-activated A-type K+ current. Many such inwardly rectifying neurons (IRNs) had a hyperpolarised resting membrane potential and some had spiny dendrites.  
    The remaining 35% of the neurons (non-IRNs) represent a heterogeneous group, including some with characteristics similar to the fast-spiking interneuron of the mammalian striatum. They showed short-lasting, large after hyperpolarisations (AHPs) and discharged action potentials at high frequency.  
    None of the recorded neurons were spontaneously active but they received GABAergic and glutamatergic synaptic input. The fact that most lamprey striatal neurons display inward rectification indicates that this is a conserved characteristic of striatal neurons throughout vertebrate phylogeny. This is a cellular property of critical importance for the operations of the striatum in mammals."  

    91 Related citations:     
    Free full text: 
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3139081/  


2012
   35<349    
Free PMC Article   
The dopamine D2 receptor gene in lamprey, its expression in the striatum and cellular effects of D2 receptor activation.

     "All basal ganglia subnuclei have recently been identified in lampreys, the phylogenetically oldest group of vertebrates. Furthermore, the interconnectivity of these nuclei is similar to mammals and tyrosine hydroxylase-positive (dopaminergic) fibers have been detected within the input layer, the striatum. Striatal processing is critically dependent on the interplay with the dopamine system, and we explore here whether D2 receptors are expressed in the lamprey striatum and their potential role. We have identified a cDNA encoding the dopamine D2 receptor from the lamprey brain and the deduced protein sequence showed close phylogenetic relationship with other vertebrate D2 receptors, and an almost 100% identity within the transmembrane domains containing the amino acids essential for dopamine binding. There was a strong and distinct expression of D2 receptor mRNA in a subpopulation of striatal neurons, and in the same region tyrosine hydroxylase-immunoreactive synaptic terminals were identified at the ultrastructural level. The synaptic incidence of tyrosine hydroxylase-immunoreactive boutons was highest in a region ventrolateral to the compact layer of striatal neurons, a region where most striatal dendrites arborise.  
    Application of a D2 receptor agonist modulates striatal neurons by causing a reduced spike discharge and a diminished post-inhibitory rebound. We conclude that the D2 receptor gene had already evolved in the earliest group of vertebrates, cyclostomes, when they diverged from the main vertebrate line of evolution (560 mya), and that it is expressed in striatum where it exerts similar cellular effects to that in other vertebrates. These results together with our previous published data (Stephenson-Jones et al. 2011, 2012) further emphasize the high degree of conservation of the basal ganglia, also with regard to the indirect loop, and its role as a basic mechanism for action selection in all vertebrates."   


2013   
30<349     
Free PMC Article   
Evolutionarily conserved differences in pallial and thalamic short-term synaptic plasticity in striatum.
    "
The striatum of the basal ganglia is conserved throughout the vertebrate phylum. Tracing studies in lamprey have shown that its afferent inputs are organized in a manner similar to that of mammals. The main inputs arise from the thalamus (Th) and lateral pallium (LPal; the homologue of cortex) that represents the two principal excitatory glutamatergic inputs in mammals.  
    The aim here was to characterize the pharmacology and synaptic dynamics of afferent fibres from the LPal and Th onto identified striatal neurons to understand the processing taking place in the lamprey striatum. We used whole-cell current-clamp recordings in acute slices of striatum with preserved fibres from the Th and LPal, as well as tract tracing and immunohistochemistry.  
    We show that the Th and LPal produce monosynaptic excitatory glutamatergic input through NMDA and AMPA receptors. The synaptic input from the LPal displayed short-term facilitation, unlike the Th input that instead displayed strong short-term synaptic depression. There was also an activity-dependent recruitment of intrastriatal oligosynaptic inhibition from both inputs. These results indicate that the two principal inputs undergo different activity-dependent short-term synaptic plasticity in the lamprey striatum.  
    The difference observed between Th and LPal (cortical) input is also observed in mammals, suggesting a conserved trait throughout vertebrate evolution."  







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