scholarly journals Thalamic state influences timing precision in the thalamocortical circuit

2021 ◽  
Author(s):  
Clarissa J Whitmire ◽  
Yi J Liew ◽  
Garrett B. Stanley
Keyword(s):  
White Noise ◽  
Cortical Neurons ◽  
Spike Timing ◽  
Sensory Stimuli ◽  
Temporal Precision ◽  
Timing Precision ◽  
State Dependent ◽  
Sensory Encoding ◽  
The Impact

Sensory signals from the outside world are transduced at the periphery, passing through thalamus before reaching cortex, ultimately giving rise to the sensory representations that enable us to perceive the world. The thalamocortical circuit is particularly sensitive to the temporal precision of thalamic spiking due to highly convergent synaptic connectivity. Thalamic neurons can exhibit burst and tonic modes of firing that strongly influence timing within the thalamus. The impact of these changes in thalamic state on sensory encoding in the cortex, however, remains unclear. Here, we investigated the role of thalamic state on timing in the thalamocortical circuit of the vibrissa pathwayin the anesthetized rat. We optogenetically hyperpolarized thalamus while recording single unit activity in both thalamus and cortex. Tonic spike triggered analysis revealed temporally precise thalamic spiking that was locked to weak white-noise sensory stimuli, while thalamic burst spiking was associated with a loss in stimulus-locked temporal precision. These thalamic state dependent changes propagated to cortex such that the cortical timing precision was diminished during the hyperpolarized (burst biased) thalamic state. While still sensory driven, the cortical neurons became significantly less precisely locked to the weak white-noise stimulus. The results here suggests a state dependent differential regulation of spike timing precision in the thalamus that could gate what signals are ultimately propagated to cortex.

scholarly journals Thalamic state influences timing precision in the thalamocortical circuit

2018 ◽  
Author(s):  
Clarissa J Whitmire ◽  
Yi Juin Liew ◽  
Garrett B Stanley
Keyword(s):  
White Noise ◽  
Sensory Information ◽  
Burst Firing ◽  
Strong Impact ◽  
Sensory Stimuli ◽  
Temporal Precision ◽  
Sensory Signals ◽  
Timing Precision ◽  
Sensory Signaling ◽  
The Impact

AbstractSensory signals from the outside world are transduced at the periphery, passing through thalamus before reaching cortex, ultimately giving rise to the sensory representations that enable us to perceive the world. The thalamocortical circuit is particularly sensitive to the temporal precision of thalamic spiking due to highly convergent synaptic connectivity. Thalamic neurons can exhibit burst and tonic modes of firing that strongly influence timing within the thalamus. The impact of these changes in thalamic state on sensory encoding in the cortex, however, remains unclear. Here, we investigated the role of thalamic state on timing in the thalamocortical circuit of the vibrissa pathway in the anesthetized rat. We optogenetically hyperpolarized thalamus while recording single unit activity in both thalamus and cortex. Tonic spike triggered analysis revealed temporally precise thalamic spiking that was locked to white-noise sensory stimuli, while thalamic burst spiking was associated with a loss in stimulus-locked temporal precision. These thalamic state dependent changes propagated to cortex such that the cortical timing precision was diminished during the hyperpolarized (burst biased) thalamic state. While still sensory driven, the cortical neurons became significantly less precisely locked to the white-noise stimulus. The results here suggest that tonic thalamic spiking is more temporally precise than burst firing, which leads to distinct differences in sensory information representation at the level of both the thalamus and the cortex, as assessed using spike triggered analysis. This difference in spike timing precision enables a dynamic encoding scheme for sensory information as a function of thalamic state.New and NoteworthyThe majority of sensory signals are transmitted through the thalamus. There is growing evidence of complex thalamic gating through coordinated firing modes that have a strong impact on cortical sensory representations. Optogenetic hyperpolarization of thalamus pushed it into burst firing that disrupted precise time-locked sensory signaling, with a direct impact on the downstream cortical encoding, setting the stage for a timing-based thalamic gate of sensory signaling.

scholarly journals Spike timing precision changes with spike rate adaptation in the owl's auditory space map

2015 ◽  
Vol 114 (4) ◽  
pp. 2204-2219 ◽  
Author(s):  
Clifford H. Keller ◽  
Terry T. Takahashi
Keyword(s):  
Carrier Frequency ◽  
Time Course ◽  
Rate Adaptation ◽  
Stimulus Level ◽  
Spike Timing ◽  
Spike Rate ◽  
Temporal Precision ◽  
Timing Precision ◽  
Spike Timing Precision

Spike rate adaptation (SRA) is a continuing change of responsiveness to ongoing stimuli, which is ubiquitous across species and levels of sensory systems. Under SRA, auditory responses to constant stimuli change over time, relaxing toward a long-term rate often over multiple timescales. With more variable stimuli, SRA causes the dependence of spike rate on sound pressure level to shift toward the mean level of recent stimulus history. A model based on subtractive adaptation (Benda J, Hennig RM. J Comput Neurosci 24: 113–136, 2008) shows that changes in spike rate and level dependence are mechanistically linked. Space-specific neurons in the barn owl's midbrain, when recorded under ketamine-diazepam anesthesia, showed these classical characteristics of SRA, while at the same time exhibiting changes in spike timing precision. Abrupt level increases of sinusoidally amplitude-modulated (SAM) noise initially led to spiking at higher rates with lower temporal precision. Spike rate and precision relaxed toward their long-term values with a time course similar to SRA, results that were also replicated by the subtractive model. Stimuli whose amplitude modulations (AMs) were not synchronous across carrier frequency evoked spikes in response to stimulus envelopes of a particular shape, characterized by the spectrotemporal receptive field (STRF). Again, abrupt stimulus level changes initially disrupted the temporal precision of spiking, which then relaxed along with SRA. We suggest that shifts in latency associated with stimulus level changes may differ between carrier frequency bands and underlie decreased spike precision. Thus SRA is manifest not simply as a change in spike rate but also as a change in the temporal precision of spiking.

State-Dependent Performance of Optic-Flow Processing Interneurons

2009 ◽  
Vol 102 (6) ◽  
pp. 3606-3618 ◽  
Author(s):  
Kit D. Longden ◽  
Holger G. Krapp
Keyword(s):  
Sensory Processing ◽  
Optic Flow ◽  
Visual Processing ◽  
Metabolic Cost ◽  
Sensory Stimuli ◽  
State Dependent ◽  
Directional Motion ◽  
Save Energy ◽  
Self Motion ◽  
The Impact

Active locomotive states are metabolically expensive and require efficient sensory processing both to avoid wasteful movements and to cope with an extended bandwidth of sensory stimuli. This is particularly true for flying animals because flight, as opposed to walking or resting, imposes a steplike increase in metabolism for the precise execution and control of movements. Sensory processing itself carries a significant metabolic cost, but the principles governing the adjustment of sensory processing to different locomotor states are not well understood. We use the blowfly as a model system to study the impact on visual processing of a neuromodulator, octopamine, which is known to be involved in the regulation of flight physiology. We applied an octopamine agonist and recorded the directional motion responses of identified visual interneurons known to process self-motion–induced optic flow to directional motion stimuli. The neural response range of these neurons is increased and the response latency is reduced. We also found that, due to an elevated spontaneous spike rate, the cells' negative signaling range is increased. Meanwhile, the preferred self-motion parameters the cells encode were state independent. Our results indicate that in the blowfly energetically expensive sensory coding strategies, such as rapid, large responses, and high spontaneous spike activity could be adjusted by the neuromodulator octopamine, likely to save energy during quiet locomotor states.

scholarly journals 450 - Exploring staff perspectives on the role of physical environment in dementia care facilities in Sweden and Canada

2020 ◽  
Vol 32 (S1) ◽  
pp. 170-170
Author(s):  
Sook Young Lee ◽  
Lillian Hung ◽  
Habib Chaudhury
Keyword(s):  
Physical Environment ◽  
Dementia Care ◽  
Care Practice ◽  
Group Method ◽  
Environmental Characteristics ◽  
Sensory Stimuli ◽  
Care Facilities ◽  
The Impact

This study explored staff perceptions of the role of physical environment in dementia care facilities in affecting resident’s behaviors and staff care practice. We used focus group method (Krueger & Casey, 2000; Krueger, 1998) to elicit staff’s shared perceptions on the impact of the physical environment on residents’ behaviors and on their own care practice. A total of 24 staff members from four facilities, two in Sweden and two in Canada, participated. Discussions in the focus groups generated rich and inter-subjective accounts via dynamic and interactive exchange among participants. Participants were explained that the researchers were particularly interested in three aspects of the physical environment: architecture or spatial layout of the setting (e.g. corridor length, bath room size, etc.), interior design aspects (e.g. lighting, flooring, furnishing, etc.) and sensory aspects (e.g. noise, smell, tactile properties, etc.). Staff in both countries reported similar physical environmental characteristics that enabled and hindered them from delivering good care. This study yielded three environmental themes that have a substantial effect on the social interaction and care practice: design ambience, space arrangement, and sensory stimuli. The deficits in the physical environmental characteristics prevented staff from providing effective person-centred care. Our findings identified substantial differences between the facilities of the two countries, although it is possible that greater differences might exist between the range of facilities in each country about the quality of environment and care. The quality of environment contributed to a high job satisfaction reported by staff in Sweden. The unsupportive and problematic features of the physical environment seemed to be the primary factor that triggers agitation among the residents with dementia in Canada.

scholarly journals Corticogeniculate feedback sharpens the temporal precision and spatial resolution of visual signals in the ferret

2017 ◽  
Vol 114 (30) ◽  
pp. E6222-E6230 ◽  
Author(s):  
J. Michael Hasse ◽  
Farran Briggs
Keyword(s):  
Spatial Resolution ◽  
Spike Timing ◽  
Visual Signals ◽  
Field Size ◽  
Response Latencies ◽  
Temporal Precision ◽  
V1 Neurons ◽  
Timing Precision ◽  
Spike Timing Precision

The corticogeniculate (CG) pathway connects the visual cortex with the visual thalamus (LGN) in the feedback direction and enables the cortex to directly influence its own input. Despite numerous investigations, the role of this feedback circuit in visual perception remained elusive. To probe the function of CG feedback in a causal manner, we selectively and reversibly manipulated the activity of CG neurons in anesthetized ferrets in vivo using a combined viral-infection and optogenetics approach to drive expression of channelrhodopsin2 (ChR2) in CG neurons. We observed significant increases in temporal precision and spatial resolution of LGN neuronal responses to drifting grating and white noise stimuli when CG neurons expressing ChR2 were light activated. Enhancing CG feedback reduced visually evoked response latencies, increased spike-timing precision, and reduced classical receptive field size. Increased precision among LGN neurons led to increased spike-timing precision among granular layer V1 neurons as well. Together, our findings suggest that the function of CG feedback is to control the timing and precision of thalamic responses to incoming visual signals.

scholarly journals Quantal Encoding of Information in a Retinal Ganglion Cell

2005 ◽  
Vol 94 (2) ◽  
pp. 1048-1056 ◽  
Author(s):  
Michael A. Freed
Keyword(s):  
White Noise ◽  
Ganglion Cell ◽  
Spike Train ◽  
Retinal Ganglion Cell ◽  
Spike Timing ◽  
Retinal Ganglion ◽  
Noise Stimulus ◽  
Excitatory Postsynaptic Currents ◽  
Temporal Precision ◽  
Postsynaptic Currents

A retinal ganglion cell receives information about a white-noise stimulus as a flickering pattern of glutamate quanta. The ganglion cell reencodes this information as brief bursts of one to six spikes separated by quiescent periods. When the stimulus is repeated, the number of spikes in a burst is highly reproducible (variance < mean) and spike timing is precise to within 10 ms, leading to an estimate that each spike encodes about 2 bits. To understand how the ganglion cell reencodes information, we studied the quantal patterns by repeating a white-noise stimulus and recording excitatory currents from a voltage-clamped, brisk-sustained ganglion cell. Quanta occurred in synchronous bursts of 3 to 65; the resulting postsynaptic currents summed to form excitatory postsynaptic currents (EPSCs). The number of quanta in an EPSC was only moderately reproducible (variance = mean), quantal timing was precise to within 14 ms, and each quantum encoded 0.1–0.4 bit. In conclusion, compared to a spike, a quantum has similar temporal precision, but is less reproducible and encodes less information. Summing multiple quanta into discrete EPSCs improves the reproducibility of the overall quantal pattern and contributes to the reproducibility of the spike train.

scholarly journals Cortical speech-evoked response patterns in multiple auditory fields are correlated with behavioral discrimination ability

2013 ◽  
Vol 110 (1) ◽  
pp. 177-189 ◽  
Author(s):  
T. M. Centanni ◽  
C. T. Engineer ◽  
M. P. Kilgard
Keyword(s):  
Cortical Neurons ◽  
Primary Auditory Cortex ◽  
Spike Timing ◽  
Response Patterns ◽  
Speech Sounds ◽  
Speech Discrimination ◽  
Discrimination Ability ◽  
Timing Information ◽  
Sensory Encoding ◽  
Behavioral Discrimination

Different speech sounds evoke unique patterns of activity in primary auditory cortex (A1). Behavioral discrimination by rats is well correlated with the distinctness of the A1 patterns evoked by individual consonants, but only when precise spike timing is preserved. In this study we recorded the speech-evoked responses in the primary, anterior, ventral, and posterior auditory fields of the rat and evaluated whether activity in these fields is better correlated with speech discrimination ability when spike timing information is included or eliminated. Spike timing information improved consonant discrimination in all four of the auditory fields examined. Behavioral discrimination was significantly correlated with neural discrimination in all four auditory fields. The diversity of speech responses across recordings sites was greater in posterior and ventral auditory fields compared with A1 and anterior auditor fields. These results suggest that, while the various auditory fields of the rat process speech sounds differently, neural activity in each field could be used to distinguish between consonant sounds with accuracy that closely parallels behavioral discrimination. Earlier observations in the visual and somatosensory systems that cortical neurons do not rely on spike timing should be reevaluated with more complex natural stimuli to determine whether spike timing contributes to sensory encoding.

scholarly journals Rapid Temporal Modulation of Synchrony by Competition in Cortical Interneuron Networks

2004 ◽  
Vol 16 (2) ◽  
pp. 251-275 ◽  
Author(s):  
P.H.E. Tiesinga ◽  
T. J. Sejnowski
Keyword(s):  
Cortical Neurons ◽  
Pyramidal Neurons ◽  
Background Activity ◽  
Pyramidal Cells ◽  
Spike Timing ◽  
Network Activity ◽  
Local Networks ◽  
Rapid Changes ◽  
Asynchronous State ◽  
The Impact

The synchrony of neurons in extrastriate visual cortex is modulated by selective attention even when there are only small changes in firing rate (Fries, Reynolds, Rorie, & Desimone, 2001). We used Hodgkin-Huxley type models of cortical neurons to investigate the mechanism by which the degree of synchrony can be modulated independently of changes in firing rates. The synchrony of local networks of model cortical interneurons interacting through GABAA synapses was modulated on a fast timescale by selectively activating a fraction of the interneurons. The activated interneurons became rapidly synchronized and suppressed the activity of the other neurons in the network but only if the network was in a restricted range of balanced synaptic background activity. During stronger background activity, the network did not synchronize, and for weaker background activity, the network synchronized but did not return to an asynchronous state after synchronizing. The inhibitory output of the network blocked the activity of pyramidal neurons during asynchronous network activity, and during synchronous network activity, it enhanced the impact of the stimulus-related activity of pyramidal cells on receiving cortical areas (Salinas & Sejnowski, 2001). Synchrony by competition provides a mechanism for controlling synchrony with minor alterations in rate, which could be useful for information processing. Because traditional methods such as cross-correlation and the spike field coherence require several hundred milliseconds of recordings and cannot measure rapid changes in the degree of synchrony, we introduced a new method to detect rapid changes in the degree of coincidence and precision of spike timing.

scholarly journals Cortical reliability amid noise and chaos

2018 ◽  
Author(s):  
Max Nolte ◽  
Michael W. Reimann ◽  
James G. King ◽  
Henry Markram ◽  
Eilif B. Muller
Keyword(s):  
Cortical Neurons ◽  
Biophysical Model ◽  
Spike Time ◽  
Cortical Circuits ◽  
Intrinsic Variability ◽  
Noise Sources ◽  
Sensory Stimuli ◽  
Simple Effect ◽  
Time Coding

Typical responses of cortical neurons to identical sensory stimuli are highly variable. It has thus been proposed that the cortex primarily uses a rate code. However, other studies have argued for spike-time coding under certain conditions. The potential role of spike-time coding is constrained by the intrinsic variability of cortical circuits, which remains largely unexplored. Here, we quantified this intrinsic variability using a biophysical model of rat neocortical microcircuitry with biologically realistic noise sources. We found that stochastic neurotransmitter release is a critical component of this variability, which, amplified by recurrent connectivity, causes rapid chaotic divergence with a time constant on the order of 10-20 milliseconds. Surprisingly, weak thalamocortical stimuli can transiently overcome the chaos, and induce reliable spike times with millisecond precision. We show that this effect relies on recurrent cortical connectivity, and is not a simple effect of feed-forward thalamocortical input. We conclude that recurrent cortical architecture supports millisecond spike-time reliability amid noise and chaotic network dynamics, resolving a long-standing debate.

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