Figure 1.
Whisker tactile deprivation upregulates olfactory sensitivity in mice.
A) shows a âTâ maze experiment to identify the olfactory sensitivity in the groups of control and whisker tactile deprivation. A mouse is placed in central arm. A food block (cheese) and a cheese-like block are randomly placed in one side of two arms. B) illustrates the statistical analysis for the successful rate of moving into cheese-containing arm versus mouse groups (two asterisks, p<0.001, n = 17).
Figure 2.
Olfactory upregulation induced by whisker tactile deprivation is associated with an elevated communication from pyramidal neurons to interneurons via excitatory synapses in the piriform cortex.
The function of excitatory synapses was evaluated by recording spontaneous excitatory postsynaptic currents (sEPSC) on the interneurons. A) shows the recorded sEPSCs on the interneurons in piriform cortex from mice of control (left panel) and whisker tactile deprivation (right). Calibration bars are 15 pA and 1 second. B) shows quantitative data about cumulative probability vs. inter-event intervals in controls (filled symbols) and whisker tactile deprivation (hollows; p<0.01, n = 9). C) shows cumulative probability versus sEPSC amplitudes in the controls (filled symbols) and whisker tactile deprivation (hollows).
Figure 3.
Olfactory upregulation induced by whisker tactile deprivation is associated with an elevated communication among the pyramidal neurons through excitatory synapses in the piriform cortex.
The function of excitatory synapses was assessed by recording sEPSC on pyramidal neurons. A) shows the recorded sEPSCs on pyramidal neurons in piriform cortex from control mice. B) shows the recorded sEPSCs on pyramidal neurons in piriform cortex from mice of whisker tactile deprivation. Calibration bars are 10 pA and 2 second. C) shows the quantitative data about cumulative probability vs. sEPSC amplitudes in the control (filled symbols) and whisker tactile deprivation (hollows; p<0.01, n = 8). D) illustrates cumulative probability vs. inter-event interval in the control (filled symbols) and whisker tactile deprivation (hollows; p<0.01, n = 8).
Figure 4.
Olfactory upregulation induced by whisker tactile deprivation is associated with an elevated capacity to encode digital spikes at pyramidal neurons of piriform cortex.
The depolarization pulses (150 ms, black trace under 4A) were injected into the neurons to evoke sequential spikes. A) shows the superimposed waveforms of sequential spikes at pyramidal neurons from a control mouse (blue trace) and a whisker tactile deprivation (red). Dash lines represent threshold potentials. B) illustrates quantitative data in inter-spike intervals at pyramidal neurons from control (blue symbols) and from whisker tactile deprivation (red symbols; an asterisk, p<0.05, n = 17).
Figure 5.
Whisker tactile deprivation attenuates the spike threshold potentials and refractory periods at pyramidal neurons of piriform cortex.
The measurement of spikes' threshold potential is showed by dash line in Fig. 4A. A) shows the measurement of refractory periods of spike-1 by two pulses at a pyramidal neuron from a control mouse (blue trace) and a whisker tactile deprivation (red trace). B) shows the statistical analyses of spikes' refractory periods at pyramidal neurons from controls (blue symbols) and whisker tactile deprivation (red symbols; n = 15, p<0.01). C) shows statistical analyses in the threshold potentials of sequential spikes at pyramidal neurons from controls (blue symbols) and whisker tactile deprivation (red symbols; n = 17, p<0.01).
Figure 6.
Olfactory upregulation induced by whisker tactile deprivation is associated with a decreased communication from GABAergic neurons to pyramidal neurons via inhibitory synapses in piriform cortex.
The function of inhibitory synapses was assessed by recording sIPSC on pyramidal neurons. A) shows the recorded sIPSCs on pyramidal neurons in piriform cortex from control mice. B) shows the recorded sIPSCs on pyramidal neurons in piriform cortex from mice of whisker tactile deprivation. Calibration bars are 10 pA and 2 second. C) shows the quantitative data about cumulative probability vs. sIPSC amplitudes in the control (filled symbols) and whisker tactile deprivation (hollows; p<0.01, n = 10). D) illustrates cumulative probability vs. inter-event interval in the control (filled symbols) and whisker tactile deprivation (hollows; p<0.01, n = 10).
Figure 7.
Olfactory upregulation induced by whisker tactile deprivation is associated with a decreased capacity in encoding digital spikes of GABAergic neurons in piriform cortex.
Depolarization pulses (150 ms, black trace under 2A) were injected into the neurons to evoke sequential spikes. A) shows the superimposed waveforms of sequential spikes at GABAergic neurons from a control mouse (blue trace) and a whisker tactile deprivation (red). Dash lines represent threshold potentials. B) illustrates quantitative data in inter-spike intervals at GABAergic neurons from control (blue symbols) and from whisker tactile deprivation (red symbols; an asterisk, p<0.05, n = 18).
Figure 8.
Whisker tactile deprivation elevates the spike threshold potentials and refractory periods at GABAergic neurons of piriform cortex.
The measurement of spikes' threshold potential is showed by dash line in Fig. 2A. A) shows a measurement of refractory periods of spike-1 by two pulses at a GABAergic neuron from a control mouse (blue trace) and a whisker tactile deprivation (red trace). B) shows the statistical analyses of spikes' refractory periods at GABAergic neurons from controls (blue symbols) and whisker tactile deprivation (red symbols; n = 16, p<0.01). C) shows statistical analyses in the threshold potentials of sequential spikes at GABAergic neurons from controls (blue symbols) and whisker tactile deprivation (red symbols; n = 18, p<0.01).
Figure 9.
The functional connection is established from the barrel cortex to the piriform cortex during olfactory upregulation induced by depriving whisker tactile input.
The activities of network neurons in barrel cortex were recorded by two-photon cellular imaging when the piriform cortex was stimulated electrically. A) shows the experimental design, in which neuronal activities in the barrel cortex were recorded under a two-photon microscope and they were activated by stimulating the piriform cortex with a bipolar tungsten electrode. B) shows the activity imaging of network neurons in the barrel cortex under the conditions of control (top panel) and whisker input deprivation (bottom). C) shows the quantitative data about the percentage of neurons in response to electrical stimulation at piriform cortex under the controls and whisker tactile input deprivation. D) illustrates the fluorescent intensity of these neurons is significantly higher in whisker input deprivation mice than control mice (p<0.001, n = 5).
Figure 10.
A schematic diagram illustrates cross-modal sensory plasticity from loss of whisker tactile input to olfactory upregulation and the involvement of GABAergic and pyramidal neurons in piriform cortex.
The right side of whiskers was cut (the deprivation of whisker tactile inputs, red-cross marker), which leads to the upregulations of olfactory sensitivity (red arrow in front of the nose) and piriform cortex. This cross-modal sensory plasticity from whisker tactile deprivation to olfactory upregulation is accompanied by the increase in the function of pyramidal neurons (orange arrow) and the decrease in the function of GABAergic neurons (green) in the piriform cortex. The information about a loss of whisker tactile inputs from the barrel cortex is transmitted to the piriform cortex via their crosswire connection.