Ultrastructural and Functional Properties of a Giant Synapse Driving the Piriform Cortex to Mediodorsal Thalamus Projection

Pelzer, Patric; Horstmann, Heinz; Kuner, Thomas

doi:10.3389/fnsyn.2017.00003

Cited by 10 publications

(15 citation statements)

References 31 publications

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“…These observations suggest that large endings in somatosensory cortex share many features with the Class 1 cortical and thalamocortical synapses. These similarities and previous findings suggest that synapses of large boutons in somatosensory cortex have high efficacy and evoke large postsynaptic responses (Amiati, 2001;Chung, Li, & Nelson, 2002;Ganeshina, Berry, Petralia, Nicholson, & Geinisman, 2004;Groh, de Kock, Wimmer, Sakmann, & Kuner, 2008;Pelzer, Horstmann, & Kuner, 2017).…”

Section: Classification Of the Cortical Axon Terminalssupporting

confidence: 85%

Synaptic organization of cortico‐cortical communication in primates

Ashaber

Zalányi

Pálfi

et al. 2020

Eur J of Neuroscience

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In cortical circuitry, synaptic communication across areas is based on two types of axon terminals, small and large, with modulatory and driving roles, respectively. In contrast, it is not known whether similar synaptic specializations exist for intra‐areal projections. Using anterograde tracing and three‐dimensional reconstruction by electron microscopy (3D‐EM), we asked whether large boutons form synapses in the circuit of somatosensory cortical areas 3b and 1. In contrast to observations in macaque visual cortex, light microscopy showed both small and large boutons not only in inter‐areal pathways, but also in long‐distance intrinsic connections. 3D‐EM showed that correlation of surface and volume provides a powerful tool for classifying cortical endings. Principal component analysis supported this observation and highlighted the significance of the size of mitochondria as a distinguishing feature of bouton type. The larger mitochondrion and higher degree of perforated postsynaptic density associated with large rather than to small boutons support the driver‐like function of large boutons. In contrast to bouton size and complexity, the size of the postsynaptic density appeared invariant across the bouton types. Comparative studies in human supported that size is a major distinguishing factor of bouton type in the cerebral cortex. In conclusion, the driver‐like function of the large endings could facilitate fast dissemination of tactile information within the intrinsic and inter‐areal circuitry of areas 3b and 1.

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Section: Classification Of the Cortical Axon Terminalssupporting

confidence: 85%

Synaptic organization of cortico‐cortical communication in primates

Ashaber

Zalányi

Pálfi

et al. 2020

Eur J of Neuroscience

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“…The complexity of the cerebello-thalamic contacts in the VL and VM seemed more prominent, in that CN terminals in these nuclei were found to contain dendritic protrusions more often than in CL. This typical structure, found also in other large terminals in thalamus, such as those formed by the piriform cortex in medial thalamus ( Pelzer et al., 2017 ), enlarge the contact surface between axon terminals and the dendrite. However, in our current dataset, we found no significant difference between the number of release sites for VL, VM, or CL.…”

Section: Discussionmentioning

confidence: 73%

Differentiating Cerebellar Impact on Thalamic Nuclei

et al. 2018

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SummaryThe cerebellum plays a role in coordination of movements and non-motor functions. Cerebellar nuclei (CN) axons connect to various parts of the thalamo-cortical network, but detailed information on the characteristics of cerebello-thalamic connections is lacking. Here, we assessed the cerebellar input to the ventrolateral (VL), ventromedial (VM), and centrolateral (CL) thalamus. Confocal and electron microscopy showed an increased density and size of CN axon terminals in VL compared to VM or CL. Electrophysiological recordings in vitro revealed that optogenetic CN stimulation resulted in enhanced charge transfer and action potential firing in VL neurons compared to VM or CL neurons, despite that the paired-pulse ratio was not significantly different. Together, these findings indicate that the impact of CN input onto neurons of different thalamic nuclei varies substantially, which highlights the possibility that cerebellar output differentially controls various parts of the thalamo-cortical network.

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“…The amygdala, a limbic region important for processing affectively salient stimuli (Baxter and Murray 2002), also projects to the medial subdivision of mediodorsal thalamus (Krettek and Price 1977a;McDonald 1987). Electron microscopy (EM) studies show that the axonal projections from these key chemosensory-related regions form different synaptic connections with neurons in mediodorsal thalamus; where amygdalar projections primarily form large synapses, gustatory cortical projections primarily form small synapses, and axons from piriform cortex make both large and small synapses (Kuroda and Price 1991a;Kuroda et al 1992;Pelzer et al 2017). Interestingly, a recent study by Pelzer et al (2017) determined that the large synapses formed by piriform axons are functionally similar to the large "driver" synapses between sensory neocortical regions and thalamus (see review (Sherman and Guillery 2011;Bickford 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Electron microscopy (EM) studies show that the axonal projections from these key chemosensory-related regions form different synaptic connections with neurons in mediodorsal thalamus; where amygdalar projections primarily form large synapses, gustatory cortical projections primarily form small synapses, and axons from piriform cortex make both large and small synapses (Kuroda and Price 1991a;Kuroda et al 1992;Pelzer et al 2017). Interestingly, a recent study by Pelzer et al (2017) determined that the large synapses formed by piriform axons are functionally similar to the large "driver" synapses between sensory neocortical regions and thalamus (see review (Sherman and Guillery 2011;Bickford 2016). These different cortical and amygdalar synaptic connections are sure to mediate many aspects of mediodorsal thalamic function, including experiencedependent responses to chemosensory stimuli.…”

Section: Discussionmentioning

confidence: 99%

Experience-Dependent c-Fos Expression in the Mediodorsal Thalamus Varies With Chemosensory Modality

2018

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The mediodorsal thalamus is a higher order thalamic nucleus critical for many cognitive behaviors. Defined by its reciprocal connections with the prefrontal cortex, the mediodorsal thalamus receives strong projections from chemosensory cortical areas for taste and smell, gustatory cortex and piriform cortex. Recent studies indicate the mediodorsal thalamus is involved in experience-dependent chemosensory processes, including olfactory attention and discrimination and the hedonic perception of odor-taste mixtures. How novel and familiar chemosensory stimuli are represented within this structure remains unclear. Here, we compared the expression of c-Fos in the mediodorsal thalami of rats familiar with an odor, a taste, or an odor-taste mixture with those that sampled the stimuli for the first time. We found that familiar tastes or odor-taste mixtures induced significantly greater c-Fos expression in the mediodorsal thalamus than novel tastes or odor-taste mixtures, whereas novel odors induced greater c-Fos expression than familiar odors. These experience-dependent and modality-specific differences in c-Fos expression may relate to the behavioral relevance of the chemosensory stimulus, including odor neophobia. In a two-bottle brief-access preference task, rats preferred water to isoamyl acetate-odorized water over multiple days. However, after experience with isoamyl acetate mixed with sucrose (odor-taste mixture), the preference for water was eliminated. These findings demonstrate that experience with chemosensory stimuli modulates responses in the mediodorsal thalamus, suggesting this structure plays an integral role in communicating behaviorally relevant chemosensory information to higher order areas to guide food-related behaviors.

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Ultrastructural and Functional Properties of a Giant Synapse Driving the Piriform Cortex to Mediodorsal Thalamus Projection

Cited by 10 publications

References 31 publications

Synaptic organization of cortico‐cortical communication in primates

Synaptic organization of cortico‐cortical communication in primates

Differentiating Cerebellar Impact on Thalamic Nuclei

Experience-Dependent c-Fos Expression in the Mediodorsal Thalamus Varies With Chemosensory Modality

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