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Social buffering suppresses fear-associated activation of the lateral amygdala in male rats: behavioral and neurophysiological evidence.

Fuzzo F, Matsumoto J, Kiyokawa Y, Takeuchi Y, Ono T, Nishijo H - Front Neurosci (2015)

Bottom Line: Although these findings suggest that the presence of a conspecific animal suppresses neural activity in the LA, direct neurophysiological evidence of suppressed activity in the LA during social buffering is still lacking.The presence of a conspecific animal significantly decreased the mean peak amplitudes of auditory evoked field potentials, gamma oscillations (25-75 Hz) and high frequency oscillations (100-300 Hz) in the LA.The results provide the first electrophysiological evidence that social buffering suppresses CS-induced activation in the LA, which consequently reduces conditioned fear responses.

View Article: PubMed Central - PubMed

Affiliation: System Emotional Science, University of Toyama Sugitani, Toyama, Japan.

ABSTRACT
In social mammals, the presence of an affiliative conspecific reduces stress responses, a phenomenon referred to as "social buffering."In a previous study, we found that the presence of a conspecific animal ameliorated a variety of stress responses to an aversive conditioned stimulus (CS), including freezing and Fos expression in the lateral amygdala (LA) of male rats. Although these findings suggest that the presence of a conspecific animal suppresses neural activity in the LA, direct neurophysiological evidence of suppressed activity in the LA during social buffering is still lacking. In the present study, we analyzed freezing behavior and local field potentials in the LA of fear-conditioned rats in response to the CS, in the presence or absence of a conspecific. After auditory aversive conditioning, the CS was presented to the conditioned rats in the presence or absence of a conspecific animal, on 2 successive days. The presence of a conspecific animal significantly decreased the mean peak amplitudes of auditory evoked field potentials, gamma oscillations (25-75 Hz) and high frequency oscillations (100-300 Hz) in the LA. Furthermore, magnitudes of these neural responses positively correlated with freezing duration of the fear-conditioned rats. The results provide the first electrophysiological evidence that social buffering suppresses CS-induced activation in the LA, which consequently reduces conditioned fear responses.

No MeSH data available.


Related in: MedlinePlus

Reduction of mean peak amplitude of the auditory evoked field potentials (AEFPs) in the Social condition. (A) Averaged AEFPs in the Alone (red) and Social (blue) conditions. The dotted line indicates CS onset. The solid lines and translucent areas indicate the means and SEMs, respectively. (B) Comparison of the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) between the conditions. *P < 0.05, unpaired t-test. (C) Locations of AEFP-recording electrodes. Circles indicate the locations. The value below each section indicates distance (mm) from the bregma. L, lateral amygdala; BL, basolateral amygdala; BM, basomedial amygdala; Me, medial amygdala; Ce, central amygdala; LV, lateral ventricle.
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Figure 2: Reduction of mean peak amplitude of the auditory evoked field potentials (AEFPs) in the Social condition. (A) Averaged AEFPs in the Alone (red) and Social (blue) conditions. The dotted line indicates CS onset. The solid lines and translucent areas indicate the means and SEMs, respectively. (B) Comparison of the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) between the conditions. *P < 0.05, unpaired t-test. (C) Locations of AEFP-recording electrodes. Circles indicate the locations. The value below each section indicates distance (mm) from the bregma. L, lateral amygdala; BL, basolateral amygdala; BM, basomedial amygdala; Me, medial amygdala; Ce, central amygdala; LV, lateral ventricle.

Mentions: AEFPs recorded during the presentation of 20 CS in the second fear-expression test were analyzed. For this test, freezing duration was significantly shorter in the Social than in the Alone condition (Social, 49 ± 10 s; Alone, 422 ± 55; Student's t-test, P < 0.001). Figure 2A shows grand averaged AEFPs across all rats, and indicates a clear peak at 22 ms after CS onset in the Alone condition, but not in the Social condition. In addition, the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) were significantly smaller in the Social than in the Alone condition (Student's t-test, P < 0.05) (Figure 2B). Tip locations of the electrodes recording AEFPs are shown in Figure 2C. All electrode tips were located within the basolateral amygdala, most of which were located in the lateral nucleus (L) of the amygdala.


Social buffering suppresses fear-associated activation of the lateral amygdala in male rats: behavioral and neurophysiological evidence.

Fuzzo F, Matsumoto J, Kiyokawa Y, Takeuchi Y, Ono T, Nishijo H - Front Neurosci (2015)

Reduction of mean peak amplitude of the auditory evoked field potentials (AEFPs) in the Social condition. (A) Averaged AEFPs in the Alone (red) and Social (blue) conditions. The dotted line indicates CS onset. The solid lines and translucent areas indicate the means and SEMs, respectively. (B) Comparison of the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) between the conditions. *P < 0.05, unpaired t-test. (C) Locations of AEFP-recording electrodes. Circles indicate the locations. The value below each section indicates distance (mm) from the bregma. L, lateral amygdala; BL, basolateral amygdala; BM, basomedial amygdala; Me, medial amygdala; Ce, central amygdala; LV, lateral ventricle.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4373252&req=5

Figure 2: Reduction of mean peak amplitude of the auditory evoked field potentials (AEFPs) in the Social condition. (A) Averaged AEFPs in the Alone (red) and Social (blue) conditions. The dotted line indicates CS onset. The solid lines and translucent areas indicate the means and SEMs, respectively. (B) Comparison of the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) between the conditions. *P < 0.05, unpaired t-test. (C) Locations of AEFP-recording electrodes. Circles indicate the locations. The value below each section indicates distance (mm) from the bregma. L, lateral amygdala; BL, basolateral amygdala; BM, basomedial amygdala; Me, medial amygdala; Ce, central amygdala; LV, lateral ventricle.
Mentions: AEFPs recorded during the presentation of 20 CS in the second fear-expression test were analyzed. For this test, freezing duration was significantly shorter in the Social than in the Alone condition (Social, 49 ± 10 s; Alone, 422 ± 55; Student's t-test, P < 0.001). Figure 2A shows grand averaged AEFPs across all rats, and indicates a clear peak at 22 ms after CS onset in the Alone condition, but not in the Social condition. In addition, the mean peak amplitudes (averaged voltages between 21 and 23 ms after CS onset) were significantly smaller in the Social than in the Alone condition (Student's t-test, P < 0.05) (Figure 2B). Tip locations of the electrodes recording AEFPs are shown in Figure 2C. All electrode tips were located within the basolateral amygdala, most of which were located in the lateral nucleus (L) of the amygdala.

Bottom Line: Although these findings suggest that the presence of a conspecific animal suppresses neural activity in the LA, direct neurophysiological evidence of suppressed activity in the LA during social buffering is still lacking.The presence of a conspecific animal significantly decreased the mean peak amplitudes of auditory evoked field potentials, gamma oscillations (25-75 Hz) and high frequency oscillations (100-300 Hz) in the LA.The results provide the first electrophysiological evidence that social buffering suppresses CS-induced activation in the LA, which consequently reduces conditioned fear responses.

View Article: PubMed Central - PubMed

Affiliation: System Emotional Science, University of Toyama Sugitani, Toyama, Japan.

ABSTRACT
In social mammals, the presence of an affiliative conspecific reduces stress responses, a phenomenon referred to as "social buffering."In a previous study, we found that the presence of a conspecific animal ameliorated a variety of stress responses to an aversive conditioned stimulus (CS), including freezing and Fos expression in the lateral amygdala (LA) of male rats. Although these findings suggest that the presence of a conspecific animal suppresses neural activity in the LA, direct neurophysiological evidence of suppressed activity in the LA during social buffering is still lacking. In the present study, we analyzed freezing behavior and local field potentials in the LA of fear-conditioned rats in response to the CS, in the presence or absence of a conspecific. After auditory aversive conditioning, the CS was presented to the conditioned rats in the presence or absence of a conspecific animal, on 2 successive days. The presence of a conspecific animal significantly decreased the mean peak amplitudes of auditory evoked field potentials, gamma oscillations (25-75 Hz) and high frequency oscillations (100-300 Hz) in the LA. Furthermore, magnitudes of these neural responses positively correlated with freezing duration of the fear-conditioned rats. The results provide the first electrophysiological evidence that social buffering suppresses CS-induced activation in the LA, which consequently reduces conditioned fear responses.

No MeSH data available.


Related in: MedlinePlus