scholarly journals Whisker-related afferents in superior colliculus

2016 ◽  
Vol 115 (5) ◽  
pp. 2265-2279 ◽  
Author(s):  
Manuel A. Castro-Alamancos ◽  
Morgana Favero
Keyword(s):  
Superior Colliculus ◽  
Granular Layer ◽  
Barrel Cortex ◽  
Sensory Responsiveness ◽  
Adult Mice ◽  
Intermediate Layers ◽  
Electrophysiological Recordings ◽  
Sensorimotor Information ◽  
Cortical Inputs

Rodents use their whiskers to explore the environment, and the superior colliculus is part of the neural circuits that process this sensorimotor information. Cells in the intermediate layers of the superior colliculus integrate trigeminotectal afferents from trigeminal complex and corticotectal afferents from barrel cortex. Using histological methods in mice, we found that trigeminotectal and corticotectal synapses overlap somewhat as they innervate the lower and upper portions of the intermediate granular layer, respectively. Using electrophysiological recordings and optogenetics in anesthetized mice in vivo, we showed that, similar to rats, whisker deflections produce two successive responses that are driven by trigeminotectal and corticotectal afferents. We then employed in vivo and slice experiments to characterize the response properties of these afferents. In vivo, corticotectal responses triggered by electrical stimulation of the barrel cortex evoke activity in the superior colliculus that increases with stimulus intensity and depresses with increasing frequency. In slices from adult mice, optogenetic activation of channelrhodopsin-expressing trigeminotectal and corticotectal fibers revealed that cells in the intermediate layers receive more efficacious trigeminotectal, than corticotectal, synaptic inputs. Moreover, the efficacy of trigeminotectal inputs depresses more strongly with increasing frequency than that of corticotectal inputs. The intermediate layers of superior colliculus appear to be tuned to process strong but infrequent trigeminal inputs and weak but more persistent cortical inputs, which explains features of sensory responsiveness, such as the robust rapid sensory adaptation of whisker responses in the superior colliculus.

scholarly journals Traumatic brain injury to primary visual cortex produces long-lasting circuit dysfunction

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jan C. Frankowski ◽  
Andrzej T. Foik ◽  
Alexa Tierno ◽  
Jiana R. Machhor ◽  
David C. Lyon ◽  
...  
Keyword(s):  
Traumatic Brain Injury ◽  
Visual Cortex ◽  
Brain Injury ◽  
Primary Visual Cortex ◽  
Visual Stimuli ◽  
Orientation Tuning ◽  
V1 Neurons ◽  
Adult Mice ◽  
Electrophysiological Recordings

AbstractPrimary sensory areas of the mammalian neocortex have a remarkable degree of plasticity, allowing neural circuits to adapt to dynamic environments. However, little is known about the effects of traumatic brain injury on visual circuit function. Here we used anatomy and in vivo electrophysiological recordings in adult mice to quantify neuron responses to visual stimuli two weeks and three months after mild controlled cortical impact injury to primary visual cortex (V1). We found that, although V1 remained largely intact in brain-injured mice, there was ~35% reduction in the number of neurons that affected inhibitory cells more broadly than excitatory neurons. V1 neurons showed dramatically reduced activity, impaired responses to visual stimuli and weaker size selectivity and orientation tuning in vivo. Our results show a single, mild contusion injury produces profound and long-lasting impairments in the way V1 neurons encode visual input. These findings provide initial insight into cortical circuit dysfunction following central visual system neurotrauma.

scholarly journals Identification of a developmental switch in information transfer between whisker S1 and S2 cortex in mice

2021 ◽  
Author(s):  
Theofanis Karayannis ◽  
Linbi Cai ◽  
Jenq-Wei Yang ◽  
Shen-Ju Chou ◽  
Chia-Fang Wang ◽  
...  
Keyword(s):  
Information Transfer ◽  
Barrel Cortex ◽  
Wide Field ◽  
Sensory Stimuli ◽  
Knock Out ◽  
Electrophysiological Recordings ◽  
Primary Sensory Cortex ◽  
Animal Navigation ◽  
Knock Out Mice

The whiskers of rodents are a key sensory organ that provides critical tactile information for animal navigation and object exploration throughout life. Previous work has explored the developmental sensory-driven activation of the primary sensory cortex processing whisker information (wS1), also called barrel cortex. This body of work has shown that the barrel cortex is already activated by sensory stimuli during the first post-natal week. However, it is currently unknown when over the course of development these stimuli begin being processed by higher order cortical areas, such as secondary whisker somatosensory area (wS2). Here we investigate for the first time the developmental engagement of wS2 by sensory stimuli and the emergence of cortico-cortical communication from wS1 to wS2. Using in vivo wide-field imaging and electrophysiological recordings in control and conditional knock-out mice we find that wS1 and wS2 are able to process bottom-up information coming from the thalamus already right after birth. We identify that it is only at the end of the first post-natal week that wS1 begins to provide excitation into wS2, a connection which begins to acquire feed-forward inhibition characteristics after the second post-natal week. Therefore, we have uncovered a developmental window during which excitatory versus inhibitory functional connectivity between wS1 and wS2 takes place.

Chronic NMDA Exposure Accelerates Development of GABAergic Inhibition in the Superior Colliculus

2000 ◽  
Vol 83 (3) ◽  
pp. 1580-1591 ◽  
Author(s):  
Sandra M. Aamodt ◽  
Jian Shi ◽  
Matthew T. Colonnese ◽  
Wellington Veras ◽  
Martha Constantine-Paton
Keyword(s):  
Superior Colliculus ◽  
Cell Voltage ◽  
Ethylene Vinyl Acetate ◽  
Cell Counting ◽  
Inhibitory Synapses ◽  
Synaptic Currents ◽  
Neuron Density ◽  
Visual Inputs ◽  
Cortical Inputs

Maturation of excitatory synaptic connections depends on the amount and pattern of their activity, and activity can affect development of inhibitory synapses as well. In the superficial visual layers of the superior colliculus (sSC), developmental increases in the effectiveness of γ-aminobutyric acid (GABAA) receptor–mediated inhibition may be driven by the maturation of visual inputs. In the rat sSC, GABAAreceptor currents significantly jump in amplitude between postnatal days 17 and 18( P17 and P18), approximately when the effects of cortical inputs are first detected in collicular neurons. We manipulated the development of these currents in vivo by implanting a drug-infused slice of the ethylene-vinyl acetate copolymer Elvax over the superior colliculus of P8 rats to chronically release from this plastic low levels of N-methyl-d-aspartate (NMDA). Sham-treated control animals received a similar implant containing only the solvent for NMDA. To examine the effects of this treatment on the development of GABA-mediated neurotransmission, we used whole cell voltage-clamp recording of spontaneous synaptic currents (sPSCs) from sSC neurons in untreated, NMDA-treated, and sham-treated superior colliculus slices ranging in age from 10 to 20 days postnatal. Both amplitude and frequency of sPSCs were studied at holding potentials of +50 mV in the presence and absence of the GABAA receptor antagonist, bicuculline methiodide (BMI). The normal developmental increase in GABAA receptor currents occurred on schedule ( P18) in sham-treated sSC, but NMDA treatment caused premature up-regulation ( P12). The average sPSCs in early NMDA-treated neurons were significantly larger than in age-matched sham controls or in age-matched, untreated neurons. No differences in average sPSC amplitudes across treatments or ages were present in BMI-insensitive, predominantly glutamatergic synaptic currents of the same neurons. NMDA treatment also significantly increased levels of glutamate decarboxylase (GAD), measured by quantitative western blotting with staining at P13 and P19. Cell counting using the dissector method for MAP 2 and GAD67 at P13 and P19indicated that the differences in GABAergic transmission were not due to increases in the proportion of inhibitory to excitatory neurons after NMDA treatment. However, chronic treatments begun at P8 with Elvax containing both NMDA and BMI significantly decreased total neuron density at P19 (∼15%), suggesting that the NMDA-induced increase in GABAA receptor currents may protect against excitotoxicity.

scholarly journals Sensory input drives rapid homeostatic scaling of the axon initial segment in mouse barrel cortex

2020 ◽  
Author(s):  
Nora Jamann ◽  
Dominik Dannehl ◽  
Robin Wagener ◽  
Corinna Corcelli ◽  
Christian Schultz ◽  
...  
Keyword(s):  
Action Potential ◽  
Initial Segment ◽  
Neuronal Excitability ◽  
Barrel Cortex ◽  
Cortical Plasticity ◽  
Sensory Deprivation ◽  
Axon Initial Segment ◽  
Electrophysiological Recordings ◽  
Network States

SummaryThe axon initial segment (AIS) is an important axonal microdomain for action potential initiation and implicated in the regulation of neuronal excitability during activity-dependent cortical plasticity. While structural AIS plasticity has been suggested to fine-tune neuronal activity when network states change, whether it acts as a homeostatic regulatory mechanism in behaviorally relevant contexts remains poorly understood. Using an in vivo model of the mouse whisker-to-barrel pathway in combination with immunofluorescence, confocal analysis and patch-clamp electrophysiological recordings, we observed bidirectional AIS plasticity. Furthermore, we find that structural and functional AIS remodeling occurs in distinct temporal domains: long-term sensory deprivation elicits an AIS length increase, accompanied with an increase in neuronal excitability, while sensory enrichment results in a rapid AIS shortening, accompanied by a decrease in action potential generation. Our findings highlight a central role of the AIS in the homeostatic regulation of neuronal input-output relations.

scholarly journals Developmental Divergence of Sensory Stimulus Representation in Cortical Interneurons

2020 ◽  
Author(s):  
Rahel Kastli ◽  
Rasmus Vighagen ◽  
Alexander van der Bourg ◽  
Ali Ozgur Argunsah ◽  
Asim Iqbal ◽  
...  
Keyword(s):  
Barrel Cortex ◽  
Cell Types ◽  
Thalamic Nuclei ◽  
Two Photon ◽  
Stimulus Representation ◽  
Adult Mice ◽  
Cortical Interneurons ◽  
Direct Input ◽  
Developmental Divergence

AbstractTwo inhibitory cell types involved in modulating barrel cortex activity and perception during active whisking in adult mice, are the VIP+ and SST+ interneurons. Here we identify a developmental transition point of structural and functional rearrangements onto these interneuron types around the start of active sensation at P14. Using in vivo two-photon Ca2+ imaging, we find that before P14, both interneuron types respond stronger to a multi-whisker stimulus, whereas after P14 their responses diverge, with VIP+ cells losing their multi-whisker preference and SST+ neurons enhancing theirs. Rabies virus tracings followed by tissue clearing, as well as photostimulation-coupled electrophysiology reveal that SST+ cells receive higher cross-barrel inputs compared to VIP+ at both time points. In addition, we also uncover that whereas prior to P14 both cell types receive direct input from the sensory thalamus, after P14 VIP+ cells show reduced inputs and SST+ cells largely shift to motor-related thalamic nuclei.

scholarly journals Activity of Cerebellar Nuclei Neurons Correlates with ZebrinII Identity of Their Purkinje Cell Afferents

Cells ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 2686
Author(s):  
Gerrit C. Beekhof ◽  
Simona V. Gornati ◽  
Cathrin B. Canto ◽  
Avraham M. Libster ◽  
Martijn Schonewille ◽  
...  
Keyword(s):  
Action Potential ◽  
Bimodal Distribution ◽  
Cerebellar Nuclei ◽  
Firing Frequency ◽  
Action Potential Firing ◽  
Adult Mice ◽  
Electrophysiological Recordings ◽  
Potential Firing

Purkinje cells (PCs) in the cerebellar cortex can be divided into at least two main subpopulations: one subpopulation that prominently expresses ZebrinII (Z+), and shows a relatively low simple spike firing rate, and another that hardly expresses ZebrinII (Z–) and shows higher baseline firing rates. Likewise, the complex spike responses of PCs, which are evoked by climbing fiber inputs and thus reflect the activity of the inferior olive (IO), show the same dichotomy. However, it is not known whether the target neurons of PCs in the cerebellar nuclei (CN) maintain this bimodal distribution. Electrophysiological recordings in awake adult mice show that the rate of action potential firing of CN neurons that receive input from Z+ PCs was consistently lower than that of CN neurons innervated by Z– PCs. Similar in vivo recordings in juvenile and adolescent mice indicated that the firing frequency of CN neurons correlates to the ZebrinII identity of the PC afferents in adult, but not postnatal stages. Finally, the spontaneous action potential firing pattern of adult CN neurons recorded in vitro revealed no significant differences in intrinsic pacemaking activity between ZebrinII identities. Our findings indicate that all three main components of the olivocerebellar loop, i.e., PCs, IO neurons and CN neurons, operate at a higher rate in the Z– modules.

scholarly journals Sensory input drives rapid homeostatic scaling of the axon initial segment in mouse barrel cortex

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nora Jamann ◽  
Dominik Dannehl ◽  
Nadja Lehmann ◽  
Robin Wagener ◽  
Corinna Thielemann ◽  
...  
Keyword(s):  
Action Potential ◽  
Initial Segment ◽  
Neuronal Excitability ◽  
Pyramidal Neurons ◽  
Barrel Cortex ◽  
Sensory Deprivation ◽  
Axon Initial Segment ◽  
Electrophysiological Recordings ◽  
Network States

AbstractThe axon initial segment (AIS) is a critical microdomain for action potential initiation and implicated in the regulation of neuronal excitability during activity-dependent plasticity. While structural AIS plasticity has been suggested to fine-tune neuronal activity when network states change, whether it acts in vivo as a homeostatic regulatory mechanism in behaviorally relevant contexts remains poorly understood. Using the mouse whisker-to-barrel pathway as a model system in combination with immunofluorescence, confocal analysis and electrophysiological recordings, we observed bidirectional AIS plasticity in cortical pyramidal neurons. Furthermore, we find that structural and functional AIS remodeling occurs in distinct temporal domains: Long-term sensory deprivation elicits an AIS length increase, accompanied with an increase in neuronal excitability, while sensory enrichment results in a rapid AIS shortening, accompanied by a decrease in action potential generation. Our findings highlight a central role of the AIS in the homeostatic regulation of neuronal input-output relations.

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