Cross-Whisker Adaptation of Neurons in the Rat Barrel Cortex

We investigated the origin of spike frequency adaptation within a layered sensory network: the auditory pathway of locusts. Spike frequency adaptation as observed in an individual neuron may arise because of intrinsic or presynaptic adaptation mechanisms. To separate the contribution of different mechanisms, we recorded from the same cell during acoustic and intracellular current stimulation. We studied three identified neuron types that are representative for each network layer and participate in processing auditory patterns and localizing sound sources. By comparing current and acoustic stimulation, three distinct patterns of the distribution of adaptation mechanisms within the sensory network emerged: (1) balanced influence of both intrinsic and presynaptic adaptation mechanisms in an interneuron that summates over several receptor afferents (TN1), (2) predominantly inhibiting input as the source for spike frequency adaptation in a cell that transmits both pattern representation and directional information (BSN1), (3) primarily intrinsic, spiketriggered adaptation currents within an interneuron coding exclusively for direction (AN2). The time courses of spike frequency adaptation differed significantly between the cells types. Using the adaptation time constants, we were able to predict signal transmission properties for the different cells. We conclude that the adaptation mechanisms differ greatly among interneurons within this sensory pathway and are a function of their role in information processing.

Section: Functional Role Of the Distribution Of Adaptation Mechanismssupporting

confidence: 86%

The Origin of Adaptation in the Auditory Pathway of Locusts Is Specific to Cell Type and Function

Hildebrandt¹,

Benda²,

Hennig³

2009

“…In these recordings the rats were anesthetized with ketamine and xylazine followed by halothane, as previously described (Katz et al, 2006;Heiss et al, 2008). The data from anesthetized animals is not included in the analysis, unless explicitly stated otherwise.…”

Section: Methodsmentioning

confidence: 99%

The Subthreshold Relation between Cortical Local Field Potential and Neuronal Firing Unveiled by Intracellular Recordings in Awake Rats

Okun¹,

Naim²,

Lampl³

2010

Self Cite

227

177

In most of the in vivo electrophysiological studies of cortical processing, which are extracellular, the spike-triggered local field potential average (LFP STA) is the measure used to estimate the correlation between the synaptic inputs of individual neuron and the local population. To understand how the magnitude and shape of LFP STA reflect the underlying correlation of synaptic activities, the membrane potential of the firing neuron has to be recorded together with the LFP. Using intracellular recordings from the cortex of awake rats, we found that for a large range of firing rates and for different behavioral states, the LFP STA represents both in its waveform and its magnitude the cross-correlation between the membrane potential of the neuron and the LFP. This data, supported by further analysis, suggests that LFP STA does not represent large network events specific to the spike times, but rather the synchrony between the mean synaptic activity of the population and the membrane potential of the single neuron, present both around spike times and in the intervals between spikes. Furthermore, it introduces a novel interpretation of the available data from unit and LFP extracellular recording experiments.

“…Animal surgeries and in vivo recordings were performed as previously described (Katz et al, 2006). Briefly, recordings were made from young adult Wistar rats (4 -7 weeks old).…”

Section: Methodsmentioning

confidence: 99%

“…At this frequency range, VPM firing achieves a steady state after only a few whisker deflections (Hellweg et al, 1977;Sosnik et al, 2001;Hartings et al, 2003;Khatri et al, 2004;Gabernet et al, 2005;Katz et al, 2006). However, cortical cells exhibit slower and more substantial adaptation Garabedian et al, 2003;Khatri et al, 2004;Derdikman et al, 2006), which probably results from short-term depression of thalamocortical synapses (Chung et al, 2002;Castro-Alamancos, 2004;Katz et al, 2006).…”

Section: Introductionmentioning

confidence: 94%

Shift in the Balance between Excitation and Inhibition during Sensory Adaptation of S1 Neurons

Heiss

Katz²,

Ganmor³

et al. 2008

Self Cite

126

131

Sustained stimulation of sensory organs results in adaptation of the neuronal response along the sensory pathway. Whether or not cortical adaptation affects equally excitation and inhibition is poorly understood. We examined this question using patch recordings of neurons in the barrel cortex of anesthetized rats while repetitively stimulating the principal whisker. We found that inhibition adapts more than excitation, causing the balance between them to shift toward excitation. A comparison of the latency of thalamic firing and evoked excitation and inhibition in the cortex strongly suggests that adaptation of inhibition results mostly from depression of inhibitory synapses rather than adaptation in the firing of inhibitory cells. The differential adaptation of the evoked conductances that shifts the balance toward excitation may act as a gain mechanism which enhances the subthreshold response during sustained stimulation, despite a large reduction in excitation.