scholarly journals Neocortical inhibitory interneuron subtypes are differentially attuned to synchrony- and rate-coded information

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Luke Y. Prince ◽  
Matthew M. Tran ◽  
Dorian Grey ◽  
Lydia Saad ◽  
Helen Chasiotis ◽  
...  
Keyword(s):  
Mutual Information ◽  
Somatosensory Cortex ◽  
Inhibitory Interneuron ◽  
Optical Stimulation ◽  
Layer 2 ◽  
Excitatory Neurons ◽  
Fast Spiking ◽  
Mouse Lines

AbstractNeurons can carry information with both the synchrony and rate of their spikes. However, it is unknown whether distinct subtypes of neurons are more sensitive to information carried by synchrony versus rate, or vice versa. Here, we address this question using patterned optical stimulation in slices of somatosensory cortex from mouse lines labelling fast-spiking (FS) and regular-spiking (RS) interneurons. We used optical stimulation in layer 2/3 to encode a 1-bit signal using either the synchrony or rate of activity. We then examined the mutual information between this signal and the interneuron responses. We found that for a synchrony encoding, FS interneurons carried more information in the first five milliseconds, while both interneuron subtypes carried more information than excitatory neurons in later responses. For a rate encoding, we found that RS interneurons carried more information after several milliseconds. These data demonstrate that distinct interneuron subtypes in the neocortex have distinct sensitivities to synchrony versus rate codes.

scholarly journals Neocortical inhibitory interneuron subtypes display distinct responses to synchrony and rate of inputs

2019 ◽  
Author(s):  
Matthew M. Tran ◽  
Luke Y. Prince ◽  
Dorian Gray ◽  
Lydia Saad ◽  
Helen Chasiotis ◽  
...  
Keyword(s):  
Mutual Information ◽  
Barrel Cortex ◽  
Inhibitory Interneuron ◽  
Optical Stimulation ◽  
Layer 2 ◽  
Fast Spiking ◽  
Cortical Microcircuit ◽  
Negative Controls ◽  
Mouse Lines ◽  
Stimulation Of

AbstractPopulations of neurons in the neocortex can carry information with both the synchrony and the rate of their spikes. However, it is unknown whether distinct subtypes of neurons in the cortical microcircuit are more sensitive to information carried by synchrony versus rate. Here, we address this question using patterned optical stimulation in slices of barrel cortex from transgenic mouse lines labelling distinct interneuron populations: fast-spiking parvalbumin-positive (PV+) and somatostatin-positive (SST+) interneurons. We use optical stimulation of channelrhodopsin-2 (ChR2) expressing excitatory neurons in layer 2/3 in order to encode a random 1-bit signal in either the synchrony or rate of activity in presynaptic cells. We then examine the mutual information between this 1-bit signal and the voltage and spiking responses in PV+ and SST+ interneurons. Generally, we find that both interneuron types carry more information than GFP negative (GFP-) control cells. More specifically, we find that for a synchrony encoding, PV+ interneurons carry more information in the first 5 milliseconds, while both interneuron subtypes carry more information than negative controls in their later response. We also find that for a rate encoding, SST+ interneurons carry more information than either PV+ or negative controls after several milliseconds. These data demonstrate that inhibitory interneuron subtypes in the neocortex have distinct responses to information carried by synchrony versus rates of spiking.

scholarly journals Increased excitation-inhibition ratio stabilizes synapse and circuit excitability in four autism mouse models

2018 ◽  
Author(s):  
Michelle W. Antoine ◽  
Philipp Schnepel ◽  
Tomer Langberg ◽  
Daniel E. Feldman
Keyword(s):  
Cerebral Cortex ◽  
Somatosensory Cortex ◽  
Mouse Models ◽  
Spike Threshold ◽  
Essentially Normal ◽  
Layer 2 ◽  
Conductance Changes ◽  
Conductance Ratio ◽  
Synaptic Drive

SummaryDistinct genetic forms of autism are hypothesized to share a common increase in excitation-inhibition (E-I) ratio in cerebral cortex, causing hyperexcitability and excess spiking. We provide the first systematic test of this hypothesis across 4 mouse models (Fmr1−/y,Cntnap2−/-,16p11.2del/+,Tsc2+/-), focusing on somatosensory cortex. All autism mutants showed reduced feedforward inhibition in layer 2/3 coupled with more modest, variable reductions in feedforward excitation, driving a common increase in E-I conductance ratio. Despite this, feedforward spiking, synaptic depolarization and spontaneous spiking were essentially normal. Modeling revealed that E and I conductance changes in each mutant were quantitatively matched to yield stable, not increased, synaptic depolarization for cells near spike threshold. Correspondingly, whisker-evoked spiking was not increasedin vivo, despite detectably reduced inhibition. Thus, elevated E-I ratio is a common circuit phenotype, but appears to reflect homeostatic stabilization of synaptic drive, rather than driving network hyperexcitability in autism.

scholarly journals Neocortical layer 4 in adult mouse differs in major cell types and circuit organization between primary sensory areas

2018 ◽  
Author(s):  
F. Scala ◽  
D. Kobak ◽  
S. Shan ◽  
Y. Bernaerts ◽  
S. Laturnus ◽  
...  
Keyword(s):  
Adult Mouse ◽  
Building Blocks ◽  
Cell Types ◽  
Excitatory Input ◽  
Excitatory Neurons ◽  
Layer 4 ◽  
Cell Type Specific ◽  
Fast Spiking ◽  
Mouse Visual Cortex ◽  
Whole Cell Recordings

AbstractLayer 4 (L4) of mammalian neocortex plays a crucial role in cortical information processing, yet a complete census of its cell types and connectivity remains elusive. Using whole-cell recordings with morphological recovery, we identified one major excitatory and seven inhibitory types of neurons in L4 of adult mouse visual cortex (V1). Nearly all excitatory neurons were pyramidal and all somatostatin-positive (SOM+) non-fast-spiking neurons were Martinotti cells. In contrast, in somatosensory cortex (S1), excitatory neurons were mostly stellate and SOM+ neurons were non-Martinotti. These morphologically distinct SOM+ interneurons corresponded to different transcriptomic cell types and were differentially integrated into the local circuit with only S1 neurons receiving local excitatory input. We propose that cell-type specific circuit motifs, such as the Martinotti/pyramidal and non-Martinotti/stellate pairs, are optionally used across the cortex as building blocks to assemble cortical circuits.

scholarly journals Eye opening differentially modulates inhibitory synaptic transmission in the developing visual cortex

2017 ◽  
Author(s):  
Wuqiang Guan ◽  
Jun-Wei Cao ◽  
Lin-Yun Liu ◽  
Zhi-Hao Zhao ◽  
Yinghui Fu ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Synaptic Transmission ◽  
Animal Development ◽  
Quantal Size ◽  
Excitatory Neurons ◽  
Artificial Opening ◽  
Eye Opening ◽  
Fast Spiking ◽  
And Function ◽  
Mouse Visual Cortex

AbstractEye opening, a natural and timed event during animal development, influences cortical circuit assembly and maturation; yet, little is known about its precise effect on inhibitory synaptic connections. Here we show that coinciding with eye opening, the strength of unitary inhibitory postsynaptic currents (uIPSCs) from somatostatin-expressing interneurons (SST-INs) to nearby excitatory neurons, but not interneurons, sharply decreases in layer 2/3 of the mouse visual cortex. In contrast, the strength of uIPSCs from fast-spiking interneurons (FS-INs) to excitatory neurons significantly increases during eye opening. More importantly, these developmental changes can be prevented by dark rearing or binocular lid suture, and reproduced by artificial opening of sutured lids. Mechanistically, this differential maturation of synaptic transmission is accompanied by a significant change in the postsynaptic quantal size. Together, our study reveals a differential regulation in GABAergic circuits in the cortex driven by eye opening likely crucial for cortical maturation and function.

scholarly journals Response Properties of Whisker-Related Neurons in Rat Second Somatosensory Cortex

2004 ◽  
Vol 92 (4) ◽  
pp. 2083-2092 ◽  
Author(s):  
Ernest E. Kwegyir-Afful ◽  
Asaf Keller
Keyword(s):  
Somatosensory Cortex ◽  
Receptive Fields ◽  
Stimulus Onset ◽  
Similar Response ◽  
Activity Levels ◽  
Response Latencies ◽  
Response Properties ◽  
Fast Spiking ◽  
Evoked Activity ◽  
Lemniscal System

In addition to a primary somatosensory cortex (SI), the cerebral cortex of all mammals contains a second somatosensory area (SII); however, the functions of SII are largely unknown. Our aim was to explore the functions of SII by comparing response properties of whisker-related neurons in this area with their counterparts in the SI. We obtained extracellular unit recordings from narcotized rats, in response to whisker deflections evoked by a piezoelectric device, and compared response properties of SI barrel (layer IV) neurons with those of SII (layers II to VI) neurons. Neurons in both cortical areas have similar response latencies and spontaneous activity levels. However, SI and SII neurons differ in several significant properties. The receptive fields of SII neurons are at least five times as large as those of barrel neurons, and they respond equally strongly to several principal whiskers. The response magnitude of SII neurons is significantly smaller than that of neurons in SI, and SII neurons are more selective for the angle of whisker deflection. Furthermore, whereas in SI fast-spiking (inhibitory) and regular-spiking (excitatory) units have different spontaneous and evoked activity levels and differ in their responses to stimulus onset and offset, SII neurons do not show significant differences in these properties. The response properties of SII neurons suggest that they are driven by thalamic inputs that are part of the paralemniscal system. Thus whisker-related inputs are processed in parallel by a lemniscal system involving SI and a paralemniscal system that processes complimentary aspects of somatosensation.

scholarly journals Efficient Recruitment of Layer 2/3 Interneurons by Layer 4 Input in Single Columns of Rat Somatosensory Cortex

2008 ◽  
Vol 28 (33) ◽  
pp. 8273-8284 ◽  
Author(s):  
M. Helmstaedter ◽  
J. F. Staiger ◽  
B. Sakmann ◽  
D. Feldmeyer
Keyword(s):  
Somatosensory Cortex ◽  
Layer 2 ◽  
Layer 4 ◽  
Rat Somatosensory Cortex

Sensory Learning Differentially Affects GABAergic Tonic Currents in Excitatory Neurons and Fast Spiking Interneurons in Layer 4 of Mouse Barrel Cortex

2010 ◽  
Vol 104 (2) ◽  
pp. 746-754 ◽  
Author(s):  
Joanna Urban-Ciecko ◽  
Małgorzata Kossut ◽  
Jerzy W. Mozrzymas
Keyword(s):  
Barrel Cortex ◽  
Spiking Neurons ◽  
Gaba Uptake ◽  
Cortical Representation ◽  
Regulation Of Expression ◽  
Sensory Learning ◽  
Excitatory Neurons ◽  
Layer 4 ◽  
Fast Spiking ◽  
The Impact

Pairing tactile stimulation of whiskers with a tail shock is known to result in expansion of cortical representation of stimulated vibrissae and in the increase in synaptic GABAergic transmission. However, the impact of such sensory learning in classical conditioning paradigm on GABAergic tonic currents has not been addressed. To this end, we performed whole cell patch-clamp slice recordings of tonic currents from neurons (excitatory regular spiking, regular spiking nonpyramidal, and fast spiking interneurons) of layer 4 of the barrel cortex from naive and trained mice. Interestingly, endogenous tonic GABAergic currents measured from the excitatory neurons in the cortical representation of “trained” vibrissae were larger than in the “naïve” or pseudoconditioned ones. On the contrary, sensory learning markedly reduced tonic currents in the fast spiking interneurons but not in regular spiking nonpyramidal neurons. Changes of tonic currents were accompanied by changes in the input resistances—decrease in regular spiking and increase in fast spiking neurons, respectively. Applications of nipecotic acid, a GABA uptake blocker, enhanced the tonic currents, but the impact of the sensory learning remained qualitatively the same as in the case of the tonic currents. Similar to endogenous tonic currents, sensory learning enhanced currents induced by THIP (superagonist for δ subunit–containing GABAA receptors) in regular spiking neurons, whereas the opposite was observed for the fast spiking interneurons. In conclusion, our data show that the sensory learning strongly affects the GABAergic tonic currents in a cell-specific manner and suggest that the underlying mechanism involves regulation of expression of δ subunit–containing GABAA receptors.

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