Inhibitory contacts on dendritic spines of the dentate fascia

Fifková, E.; Eason, Helen; Schaner, Pamela J.

doi:10.1016/0006-8993(92)90293-i

Cited by 28 publications

(17 citation statements)

References 26 publications

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“…A similar pattern of termination of inhibitory input on granule cell bodies and in the molecular layer has been reported in anatomical studies of the dentate gyrus in the rat (Gottlieb and Cowan, 1972;Amaral, 1978;Ribak and Seress, 1983;Seress and Ribak, 1983;Schlander et al, 1987;Fifkova et al, 1992;Halasy and Somogyi, 1993;Ribak et al, 1993;Seress et al, 1993;Buhl et al, 1994).…”

Section: Inhibitory Circuitrymentioning

confidence: 50%

Alterations of inhibitory synaptic responses in the dentate gyrus of temporal lobe epileptic patients

1994

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The number of orthodromically evoked population spikes was used to classify brain slice tissue from the dentate gyrus of temporal lobe epileptic patients as "more excitable" (multiple population spikes) or "less excitable" (a single population spike). During orthodromic stimulation, "more excitable" tissue exhibited less paired-pulse depression in comparison to "less excitable" tissue. During antidromic stimulation, both multiple population spikes and paired-pulse depression were observed in "more excitable" tissue. "Less excitable" tissue exhibited a single antidromic spike and often no antidromically evoked paired-pulse depression. The strength of antidromic paired-pulse depression was correlated positively with the number of antidromic spikes and was correlated negatively with orthodromic paired-pulse depression. Although orthodromic and antidromic paired-pulse depression were correlated to the number of orthodromically evoked population spikes, this correlation was not as strong as that between orthodromic paired-pulse depression, antidromic paired-pulse depression, and number of antidromically evoked population spikes. The antidromic paired-pulse depression observed in tissue exhibiting antidromically evoked multiple population spikes was enhanced rather than blocked by bicuculline. In addition, the blockade of the antidromic paired-pulse depression by CNQX indicated that this inhibition is mediated by an AMPA-type glutamatergic synapse. We suggest that alterations in circuitry occur in the dentate gyrus of some temporal lobe epileptic patients and were manifested by both a loss of inhibitory input as well as an increase of inhibition, which was dependent on the pathway of stimulation. The results of pairing antidromic and orthodromic stimuli were consistent with these conclusions.

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Section: Inhibitory Circuitrymentioning

confidence: 50%

Alterations of inhibitory synaptic responses in the dentate gyrus of temporal lobe epileptic patients

1994

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“…The convergence of synapses that vary ultrastructurally (symmetric vs asymmetric) or immunocytochemically (GABAergic or cholinergic vs glutamatergic) on the same dendrite has been described in the neocortex of the cat (Jones and Powell, 1969a), in the hippocampal formations of the rat Lérá nth and Frotscher, 1986;Soriano and Frotscher, 1993), in the amygdala of the rat (Nitecka and Frotscher, 1989), in the mouse sensory cortex (Keller and White, 1987), in the striatum of the rat (Shi-yun et al, 1992), on dendritic spines in the dentate fascia of the mouse (Fifková et al, 1992), and occasionally on the dendritic spines of the rat cerebral cortex (Peters and Kaiserman-Abramof, 1970). In the monkey striate cortex, about every fourth GABAergic synapse is on a spine that receives both an inhibitory and an excitatory synapse (Beaulieu et al, 1992).…”

Section: Converging Synapsesmentioning

confidence: 88%

Compound synapses within the GABAergic innervation of the auditory inner hair cells in the adolescent mouse

et al. 1997

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Ultrastructural investigation of the gamma-aminobutyric acid (GABA) component of the inner spiral bundle in adolescent mice revealed a pathway of glutamic acid decarboxylase (GAD)-positive and -negative fibers and vesiculated endings that contact inner hair cells and their afferents through a complex of axosomatic and axodendritic synapses. Ultrastructural details were investigated by using conventional electron microscopy. Several synaptic arrangements were observed: Main axosomatic synapses form between vesiculated endings and individual or adjoining inner hair cells (interreceptor synapses). Spinous synapses form on long, spinelike processes that protrude from inner hair cells to reach distant efferent endings. The efferent endings associate with inner hair cells and their synaptic afferents through compound synapses-serial, "converging," and triadic-otherwise characteristic of sensory relay nuclei. Serial synapses form by the sequential presynaptic alignment of the efferent-->receptor-->afferent components. Converging synapses result from the simultaneous apposition of a receptor ribbon synapse and a presynaptic efferent terminal on a recipient afferent dendrite. Triadic synapses comprise a vesiculated efferent ending in contact with an inner hair cell and with its synaptic afferent. Additionally, efferent endings may form simple axodendritic and axoaxonal synapses with GAD-negative vesiculated endings. The combination of different synaptic arrangements leads to short chains of compound synapses. It is assumed that these synaptic patterns seen in the adolescent mouse represent adult synaptology. The patterns of synaptic connectivity suggest an integrative role for the GABA/GAD lateral efferent system, and imply its involvement in the pre- and postsynaptic modulation of auditory signals.

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“…Perhaps spineless Pleo terminals result from fluidity in the formation / retraction of spines (Alvarez and Sabatini, 2007). Elsewhere in the brain, inhibitory terminals associated with spines are rare but are found in the visual cortex (Colonnier, 1968), and, along with excitatory inputs, can be found on some spines in the cortical barrel fields (Knott et al, 2002) and in the dentate fascia (Fifková et al, 1992). In the case of the middle ear muscle reflex, the reflex is driven by excitatory input, which means that the spine-associated inhibitory synapses perform a modulatory role rather than drive the reflex.…”

Section: Discussionmentioning

confidence: 99%

Ultrastructure of spines and associated terminals on brainstem neurons controlling auditory input

2013

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Spines are unique cellular appendages that isolate synaptic input to neurons and play a role in synaptic plasticity. Using the electron microscope, we studied spines and their associated synaptic terminals on three groups of brainstem neurons: tensor tympani motoneurons, stapedius motoneurons, and medial olivocochlear neurons, all of which exert reflexive control of processes in the auditory periphery. These spines are generally simple in shape; they are infrequent and found on the somata as well as the dendrites. Spines do not differ in volume among the three groups of neurons. In all cases, the spines are associated with a synaptic terminal that engulfs the spine rather than abuts its head. The positions of the synapses are variable, and some are found at a distance from the spine, suggesting that the isolation of synaptic input is of diminished importance for these spines. Each group of neurons receives three common types of synaptic terminals. The type of terminal associated with spines of the motoneurons contains pleomorphic vesicles, whereas the type associated with spines of olivocochlear neurons contains large round vesicles. Thus, spine-associated terminals in the motoneurons appear to be associated with inhibitory processes but in olivocochlear neurons they are associated with excitatory processes.

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Inhibitory contacts on dendritic spines of the dentate fascia

Cited by 28 publications

References 26 publications

Alterations of inhibitory synaptic responses in the dentate gyrus of temporal lobe epileptic patients

Alterations of inhibitory synaptic responses in the dentate gyrus of temporal lobe epileptic patients

Compound synapses within the GABAergic innervation of the auditory inner hair cells in the adolescent mouse

Ultrastructure of spines and associated terminals on brainstem neurons controlling auditory input

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