scholarly journals Differential serotonergic modulation of principal neurons and interneurons in the anterior piriform cortex

2022 ◽  
Author(s):  
Magor L Lőrincz ◽  
Ildikó Piszár
Keyword(s):  
Piriform Cortex ◽  
Sensory Information ◽  
Olfactory Cortex ◽  
Anterior Piriform Cortex ◽  
Electrophysiological Recordings ◽  
Primary Olfactory Cortex ◽  
Brainstem Raphe ◽  
Evoked Activity ◽  
Sensory Evoked

Originating from the brainstem raphe nuclei, serotonin is an important neuromodulator involved in a variety of physiological and pathological functions. Specific optogenetic stimulation of serotonergic neurons results in the divisive suppression of spontaneous, but not sensory evoked activity in the majority of neurons in the primary olfactory cortex and an increase in firing in a minority of neurons. To reveal the mechanisms involved in this dual serotonergic control of cortical activity we used a combination of in vitro electrophysiological recordings from identified neurons in the primary olfactory cortex, optogenetics and pharmacology and found that serotonin suppressed the activity of principal neurons, but excited local interneurons. The results have important implications in sensory information processing and other functions of the olfactory cortex and related brain areas.

scholarly journals Representational drift in primary olfactory cortex

2020 ◽  
Author(s):  
Carl E. Schoonover ◽  
Sarah N. Ohashi ◽  
Richard Axel ◽  
Andrew J.P. Fink
Keyword(s):  
Olfactory System ◽  
Piriform Cortex ◽  
External World ◽  
Olfactory Cortex ◽  
Linear Classifier ◽  
Electrophysiological Recordings ◽  
Primary Olfactory Cortex ◽  
Sensory Cortices ◽  
The Stability

SummaryRepresentations of the external world in sensory cortices may define the identity of a stimulus and should therefore vary little over the life of the organism. In the olfactory system the primary olfactory cortex, piriform, is thought to determine odor identity1–6. We have performed electrophysiological recordings of single units maintained over weeks to examine the stability of odor representations in the mouse piriform cortex. We observed that odor representations drift over time, such that the performance of a linear classifier trained on the first recording day approaches chance levels after 32 days. Daily exposure to the same odorant slows the rate of drift, but when exposure is halted that rate increases once again. Moreover, behavioral salience does not stabilize odor representations. Continuous drift poses the question of the role of piriform in odor identification. This instability may reflect the unstructured connectivity of piriform7–15 and may be a property of other unstructured cortices.

scholarly journals Active information maintenance in working memory by a sensory cortex

2018 ◽  
Author(s):  
Xiaoxing Zhang ◽  
Wenjun Yan ◽  
Wenliang Wang ◽  
Hongmei Fan ◽  
Ruiqing Hou ◽  
...  
Keyword(s):  
Working Memory ◽  
Piriform Cortex ◽  
Delay Period ◽  
Sensory Cortex ◽  
Critical Function ◽  
Impaired Performance ◽  
Anterior Piriform Cortex ◽  
Electrophysiological Recordings ◽  
Dual Task Paradigm ◽  
The Brain

SummaryWorking memory is a critical function of the brain to maintain and manipulate information over delay periods of seconds. Sensory areas have been implicated in working memory; however, it is debated whether the delay-period activity of sensory regions is actively maintaining information or passively reflecting top-down inputs. We hereby examined the anterior piriform cortex, an olfactory cortex, in head-fixed mice performing a series of olfactory working memory tasks. Information maintenance is necessary in these tasks, especially in a dual-task paradigm in which mice are required to perform another distracting task while actively maintaining information during the delay period. Optogenetic suppression of the piriform cortex activity during the delay period impaired performance in all the tasks.Furthermore, electrophysiological recordings revealed that the delay-period activity of the anterior piriform cortex encoded odor information with or without the distracting task.Thus, this sensory cortex is critical for active information maintenance in working memory.

Time Course of Odorant-Induced Activation in the Human Primary Olfactory Cortex

2000 ◽  
Vol 83 (1) ◽  
pp. 537-551 ◽  
Author(s):  
Noam Sobel ◽  
Vivek Prabhakaran ◽  
Zuo Zhao ◽  
John E. Desmond ◽  
Gary H. Glover ◽  
...  
Keyword(s):  
Time Course ◽  
Piriform Cortex ◽  
Signal Amplitude ◽  
Olfactory Cortex ◽  
Transient Increase ◽  
Functional Neuroanatomy ◽  
Functional Magnetic Resonance ◽  
Physiological Level ◽  
Temporal Variance ◽  
Primary Olfactory Cortex

Paradoxically, attempts to visualize odorant-induced functional magnetic resonance imaging (fMRI) activation in the human have yielded activations in secondary olfactory regions but not in the primary olfactory cortex-piriform cortex. We show that odorant-induced activation in primary olfactory cortex was not previously made evident with fMRI because of the unique time course of activity in this region: in primary olfactory cortex, odorants induced a strong early transient increase in signal amplitude that then habituated within 30–40 s of odorant presence. This time course of activation seen here in the primary olfactory cortex of the human is almost identical to that recorded electrophysiologically in the piriform cortex of the rat. Mapping activation with analyses that are sensitive to both this transient increase in signal amplitude, and temporal-variance, enabled us to use fMRI to consistently visualize odorant-induced activation in the human primary olfactory cortex. The combination of continued accurate odorant detection at the behavioral level despite primary olfactory cortex habituation at the physiological level suggests that the functional neuroanatomy of the olfactory response may change throughout prolonged olfactory stimulation.

scholarly journals The Neurotransmitter Receptor Architecture of the Mouse Olfactory System

2021 ◽  
Vol 15 ◽  
Author(s):  
Kimberley Lothmann ◽  
Katrin Amunts ◽  
Christina Herold
Keyword(s):  
Olfactory System ◽  
Piriform Cortex ◽  
Hierarchical Cluster ◽  
Distribution Patterns ◽  
Olfactory Cortex ◽  
Cluster Solution ◽  
Olfactory Tubercle ◽  
Neurotransmitter Receptor ◽  
Heterogeneous Expression

The uptake, transmission and processing of sensory olfactory information is modulated by inhibitory and excitatory receptors in the olfactory system. Previous studies have focused on the function of individual receptors in distinct brain areas, but the receptor architecture of the whole system remains unclear. Here, we analyzed the receptor profiles of the whole olfactory system of adult male mice. We examined the distribution patterns of glutamatergic (AMPA, kainate, mGlu2/3, and NMDA), GABAergic (GABAA, GABAA(BZ), and GABAB), dopaminergic (D1/5) and noradrenergic (α1 and α2) neurotransmitter receptors by quantitative in vitro receptor autoradiography combined with an analysis of the cyto- and myelo-architecture. We observed that each subarea of the olfactory system is characterized by individual densities of distinct neurotransmitter receptor types, leading to a region- and layer-specific receptor profile. Thereby, the investigated receptors in the respective areas and strata showed a heterogeneous expression. Generally, we detected high densities of mGlu2/3Rs, GABAA(BZ)Rs and GABABRs. Noradrenergic receptors revealed a highly heterogenic distribution, while the dopaminergic receptor D1/5 displayed low concentrations, except in the olfactory tubercle and the dorsal endopiriform nucleus. The similarities and dissimilarities of the area-specific multireceptor profiles were analyzed by a hierarchical cluster analysis. A three-cluster solution was found that divided the areas into the (1) olfactory relay stations (main and accessory olfactory bulb), (2) the olfactory cortex (anterior olfactory cortex, dorsal peduncular cortex, taenia tecta, piriform cortex, endopiriform nucleus, entorhinal cortex, orbitofrontal cortex) and the (3) olfactory tubercle, constituting its own cluster. The multimodal receptor-architectonic analysis of each component of the olfactory system provides new insights into its neurochemical organization and future possibilities for pharmaceutic targeting.

Afferent and association fiber differences in short-term potentiation in piriform (olfactory) cortex of the rat

1990 ◽  
Vol 64 (1) ◽  
pp. 179-190 ◽  
Author(s):  
M. E. Hasselmo ◽  
J. M. Bower
Keyword(s):  
Time Constant ◽  
Piriform Cortex ◽  
Low Frequency ◽  
Pyramidal Cells ◽  
Olfactory Cortex ◽  
Short Term ◽  
Term Potentiation ◽  
Association Fibers ◽  
Stimulation Of

1. The effects of low-frequency stimulus trains on synaptically evoked responses in piriform cortex pyramidal cells were studied by the use of intracellular recording techniques in an in vitro slice preparation. Afferent and association fiber systems were differentially stimulated with electrodes placed in layer 1a or layer 1b, respectively. To quantify synapse modifiability, the heights of postsynaptic potentials (PSPs) elicited by paired-pulse stimulation (100-ms interval) were averaged over a 50-s period before and after a set of 10 stimulus trains (10 pulses each, 20 Hz, 5-s interpulse interval). 2. Afferent and association fibers showed consistent differences in their response to stimulation during the period lasting from approximately 10 to 200 s after presentation of trains. During this time period, the responses to stimulation of association fibers in layer 1b displayed a short-term potentiation, which over the 10 posttrain trials, produced an average increase in PSP height of 23.2 +/- 3.7% (mean +/- SE). On the other hand, responses to layer 1a stimulation showed an average depression of 10.9 +/- 3.6%. Layer 1b potentiation decayed with time constant roughly estimated at 79 s. Layer 1b potentiation appeared even at very low stimulus voltages and after local association fiber input had been cut, suggesting that it was largely a monosynaptic effect. 3. In the period immediately after train presentations, responses evoked by both layers showed a short-term augmentation with a time constant around 3 s. In layer 1a, this augmentation was superimposed on a depression with slow recovery. At longer times after train presentation (greater than 5 min), 2 cells out of 46 showed changes (increases) in synaptic efficacy in response to layer 1b stimulation. 4. In the current experiments both layers 1a and 1b showed statistically significant facilitation before the presentation of stimulus trains. However, layer 1b facilitation decreased from 22.7 +/- 3.5% to a statistically insignificant 3.9 +/- 3.3% after the presentation of trains, whereas layer 1a facilitation remained at a statistically significant level of 23.1 +/- 5.7%. 5. These experiments show that pyramidal cell responses to stimulation of the afferent and association fiber systems are affected differently by the previous presentation of trains of stimuli. This suggests that mechanisms of synaptic modification may differ between the afferent and intrinsic association synaptic projections onto single pyramidal cells in olfactory cortex.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Temporal coordination of olfactory cortex sharp-wave activity with up- and downstates in the orbitofrontal cortex during slow-wave sleep

2017 ◽  
Vol 117 (1) ◽  
pp. 123-135 ◽  
Author(s):  
Naomi Onisawa ◽  
Hiroyuki Manabe ◽  
Kensaku Mori
Keyword(s):  
Slow Wave ◽  
Orbitofrontal Cortex ◽  
Slow Wave Sleep ◽  
Time Windows ◽  
Late Phase ◽  
Piriform Cortex ◽  
Olfactory Cortex ◽  
Field Potentials ◽  
Temporal Coordination ◽  
Anterior Piriform Cortex

During slow-wave sleep, interareal communications via coordinated, slow oscillatory activities occur in the large-scale networks of the mammalian neocortex. Because olfactory cortex (OC) areas, which belong to paleocortex, show characteristic sharp-wave (SPW) activity during slow-wave sleep, we examined whether OC SPWs in freely behaving rats occur in temporal coordination with up- and downstates of the orbitofrontal cortex (OFC) slow oscillation. Simultaneous recordings of local field potentials and spike activities in the OC and OFC showed that during the downstate in the OFC, the OC also exhibited downstate with greatly reduced neuronal activity and suppression of SPW generation. OC SPWs occurred during two distinct phases of the upstate of the OFC: early-phase SPWs occurred at the start of upstate shortly after the down-to-up transition in the OFC, whereas late-phase SPWs were generated at the end of upstate shortly before the up-to-down transition. Such temporal coordination between neocortical up- and downstates and olfactory system SPWs was observed between the prefrontal cortex areas (OFC and medial prefrontal cortex) and the OC areas (anterior piriform cortex and posterior piriform cortex). These results suggest that during slow-wave sleep, OC and OFC areas communicate preferentially in specific time windows shortly after the down-to-up transition and shortly before the up-to-down transition. NEW & NOTEWORTHY Simultaneous recordings of local field potentials and spike activities in the anterior piriform cortex (APC) and orbitofrontal cortex (OFC) during slow-wave sleep showed that APC sharp waves tended to occur during two distinct phases of OFC upstate: early phase, shortly after the down-to-up transition, and late phase, shortly before the up-to-down transition, suggesting that during slow-wave sleep, olfactory cortex and OFC areas communicate preferentially in the specific time windows.

Time-Dependent, Layer-Specific Modulation of Sensory Responses Mediated by Neocortical Layer 1

2006 ◽  
Vol 96 (6) ◽  
pp. 3170-3182 ◽  
Author(s):  
Dan Shlosberg ◽  
Yael Amitai ◽  
Rony Azouz
Keyword(s):  
Somatosensory Cortex ◽  
Cortical Neurons ◽  
Sensory Information ◽  
Time Dependent ◽  
Inhibitory Influence ◽  
Sensory Responses ◽  
Specific Regulation ◽  
Sensory Evoked

An essential component of feedback and top-down information in the cortical column arrives at layer 1 (L1) where it contacts distal dendrites of pyramidal neurons. Although much is known about the anatomical organization of L1 fibers, their contribution to sensory information processing remains to be determined. We assessed the physiological significance of L1 inputs by performing extracellular recordings in vivo from neurons in the primary somatosensory cortex of rodents. We found that blocking activity in L1 increases whisker-evoked response magnitude and variance, suggesting that L1 exerts an inhibitory influence on whisker responses. However, when pairing L1 stimulation with whisker deflection, the interval between the stimuli determined the outcome of the interaction, with facilitation of sensory responses dominating the short intervals (≤10 ms) and suppression prevailing at longer intervals (>10 ms). These temporal interactions resulted in a time-dependent regulation of direction tuning of cortical neurons. The synaptic mechanisms underlying L1 inputs’ influences were examined using whole cell recordings in vitro while pairing L1 and white-matter stimulations. We found time-dependent, layer-specific differences in synaptic summation of the two inputs, with supralinearity at shorter intervals and sublinearity at longer intervals that resulted mainly from shunting inhibition. Taken together, our results demonstrate that L1 inputs impose a time- and layer-specific regulation on sensory-evoked responses. This in turn may lead to a dynamic transmission of sensory information in the somatosensory cortex.

scholarly journals Contribution of interneuron subtype-specific GABAergic signalling to emergent sensory processing in somatosensory whisker barrel cortex in mouse

2021 ◽  
Author(s):  
Liad J. Baruchin ◽  
Michael M. Kohl ◽  
Simon J.B Butt
Keyword(s):  
Sensory Processing ◽  
Barrel Cortex ◽  
Sensory Information ◽  
Gaba Release ◽  
Gabaergic Interneuron ◽  
Dependent Manner ◽  
Sensory Adaptation ◽  
Layer 4 ◽  
Evoked Activity ◽  
Sensory Evoked

AbstractMammalian neocortex is important for conscious processing of sensory information. Fundamental to this function is balanced glutamatergic and GABAergic signalling. Yet little is known about how this interaction arises in the developing forebrain despite increasing insight into early GABAergic interneuron (IN) circuits. To further study this, we assessed the contribution of specific INs to the development of sensory processing in the mouse whisker barrel cortex. Specifically we explored the role of INs in speed coding and sensory adaptation. In wild-type animals, both speed processing and adaptation were present as early as the layer 4 critical period of plasticity, and showed refinement over the period leading to active whisking onset. We then conditionally silenced action-potential-dependent GABA release in either somatostatin (SST) or vasoactive intestinal peptide (VIP) INs. These genetic manipulations influenced both spontaneous and sensory-evoked activity in an age and layer-dependent manner. Silencing SST+ INs reduced early spontaneous activity and abolished facilitation in sensory adaptation observed in control pups. In contrast, VIP+ IN silencing had an effect towards the onset of active whisking. Silencing either IN subtype had no effect on speed coding. Our results reveal how these IN subtypes differentially contribute to early sensory processing over the first few postnatal weeks.

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