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The role of the hippocampus in avoidance learning and anxiety vulnerability.

Cominski TP, Jiao X, Catuzzi JE, Stewart AL, Pang KC - Front Behav Neurosci (2014)

Bottom Line: In the current study, we examined the effect of hippocampal damage in avoidance learning, as avoidance is a core symptom of all anxiety disorders.The WKY rat is an animal model of behavioral inhibition, a risk factor for anxiety, and demonstrates abnormal avoidance learning, marked by facilitated avoidance acquisition and resistance to extinction.These results suggest that hippocampal dysfunction enhances the development of persistent avoidance responding and, thus, may confer vulnerability to the development of anxiety disorders and PTSD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neurosciences, Rutgers - New Jersey Medical School, Rutgers, The State University of New Jersey , Newark, NJ , USA.

ABSTRACT
The hippocampus has been implicated in anxiety disorders and post-traumatic stress disorder (PTSD); human studies suggest that a dysfunctional hippocampus may be a vulnerability factor for the development of PTSD. In the current study, we examined the effect of hippocampal damage in avoidance learning, as avoidance is a core symptom of all anxiety disorders. First, the effect of hippocampal damage on avoidance learning was investigated in outbred Sprague Dawley (SD) rats. Second, the function of the hippocampus in Wistar-Kyoto (WKY) rats was compared to SD rats. The WKY rat is an animal model of behavioral inhibition, a risk factor for anxiety, and demonstrates abnormal avoidance learning, marked by facilitated avoidance acquisition and resistance to extinction. The results of the current study indicate that hippocampal damage in SD rats leads to impaired extinction of avoidance learning similar to WKY rats. Furthermore, WKY rats have reduced hippocampal volume and impaired hippocampal synaptic plasticity as compared to SD rats. These results suggest that hippocampal dysfunction enhances the development of persistent avoidance responding and, thus, may confer vulnerability to the development of anxiety disorders and PTSD.

No MeSH data available.


Related in: MedlinePlus

LTP of the dentate gyrus field EPSP (fEPSP) following HFS of the medial perforant pathway in SD and WKY rats. SD rats exhibited early and late phase LTP of the fEPSP (A). In contrast, WKY rats did not demonstrate LTP at either early or late time points (B). Displayed are input–output (i/o) curves showing the baseline response, early phase LTP and late phase LTP. Shown are an average of two i/o curves generated prior to HFS (baseline), an average of i/o curves generated 15-min and 1-h after HFS (early), and an average of i/o curves generated 2- and 3-h after HFS (late).
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Figure 6: LTP of the dentate gyrus field EPSP (fEPSP) following HFS of the medial perforant pathway in SD and WKY rats. SD rats exhibited early and late phase LTP of the fEPSP (A). In contrast, WKY rats did not demonstrate LTP at either early or late time points (B). Displayed are input–output (i/o) curves showing the baseline response, early phase LTP and late phase LTP. Shown are an average of two i/o curves generated prior to HFS (baseline), an average of i/o curves generated 15-min and 1-h after HFS (early), and an average of i/o curves generated 2- and 3-h after HFS (late).

Mentions: Long-term potentiation (LTP) of the mPP to DG synapse was impaired in WKY rats. Evoked field potentials had similar waveforms in SD and WKY rats (Figure 5). LTP of the fEPSP was observed in SD rats, but not in WKY rats (Figures 6A,B). In SD rats, both early phase LTP (15 min and 1 h after HFS) and late phase LTP (2 and 3 h after HFS) were observed, as main effect of phase [F(2, 10) = 5.229 p = 0.028] and the phase × stimulus intensity interaction [F(12,60) = 4.507, p < 0.001] were significant (Figure 6A). The main effect of stimulus intensity was also significant, [F(6,30) = 13.139, p < 0.001]. In contrast to SD rats, LTP of the fEPSP was not observed in WKY rats (Figure 6B). Neither main effect of phase [F(2,10) = 1.913, p = 0.198] nor the phase × stimulus intensity interaction [F(12,60) = 1.794, p = 0.07] were significant. The main effect of stimulus intensity was significant, [F(6,30) = 22.234 p < 0.001].


The role of the hippocampus in avoidance learning and anxiety vulnerability.

Cominski TP, Jiao X, Catuzzi JE, Stewart AL, Pang KC - Front Behav Neurosci (2014)

LTP of the dentate gyrus field EPSP (fEPSP) following HFS of the medial perforant pathway in SD and WKY rats. SD rats exhibited early and late phase LTP of the fEPSP (A). In contrast, WKY rats did not demonstrate LTP at either early or late time points (B). Displayed are input–output (i/o) curves showing the baseline response, early phase LTP and late phase LTP. Shown are an average of two i/o curves generated prior to HFS (baseline), an average of i/o curves generated 15-min and 1-h after HFS (early), and an average of i/o curves generated 2- and 3-h after HFS (late).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4125878&req=5

Figure 6: LTP of the dentate gyrus field EPSP (fEPSP) following HFS of the medial perforant pathway in SD and WKY rats. SD rats exhibited early and late phase LTP of the fEPSP (A). In contrast, WKY rats did not demonstrate LTP at either early or late time points (B). Displayed are input–output (i/o) curves showing the baseline response, early phase LTP and late phase LTP. Shown are an average of two i/o curves generated prior to HFS (baseline), an average of i/o curves generated 15-min and 1-h after HFS (early), and an average of i/o curves generated 2- and 3-h after HFS (late).
Mentions: Long-term potentiation (LTP) of the mPP to DG synapse was impaired in WKY rats. Evoked field potentials had similar waveforms in SD and WKY rats (Figure 5). LTP of the fEPSP was observed in SD rats, but not in WKY rats (Figures 6A,B). In SD rats, both early phase LTP (15 min and 1 h after HFS) and late phase LTP (2 and 3 h after HFS) were observed, as main effect of phase [F(2, 10) = 5.229 p = 0.028] and the phase × stimulus intensity interaction [F(12,60) = 4.507, p < 0.001] were significant (Figure 6A). The main effect of stimulus intensity was also significant, [F(6,30) = 13.139, p < 0.001]. In contrast to SD rats, LTP of the fEPSP was not observed in WKY rats (Figure 6B). Neither main effect of phase [F(2,10) = 1.913, p = 0.198] nor the phase × stimulus intensity interaction [F(12,60) = 1.794, p = 0.07] were significant. The main effect of stimulus intensity was significant, [F(6,30) = 22.234 p < 0.001].

Bottom Line: In the current study, we examined the effect of hippocampal damage in avoidance learning, as avoidance is a core symptom of all anxiety disorders.The WKY rat is an animal model of behavioral inhibition, a risk factor for anxiety, and demonstrates abnormal avoidance learning, marked by facilitated avoidance acquisition and resistance to extinction.These results suggest that hippocampal dysfunction enhances the development of persistent avoidance responding and, thus, may confer vulnerability to the development of anxiety disorders and PTSD.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology and Neurosciences, Rutgers - New Jersey Medical School, Rutgers, The State University of New Jersey , Newark, NJ , USA.

ABSTRACT
The hippocampus has been implicated in anxiety disorders and post-traumatic stress disorder (PTSD); human studies suggest that a dysfunctional hippocampus may be a vulnerability factor for the development of PTSD. In the current study, we examined the effect of hippocampal damage in avoidance learning, as avoidance is a core symptom of all anxiety disorders. First, the effect of hippocampal damage on avoidance learning was investigated in outbred Sprague Dawley (SD) rats. Second, the function of the hippocampus in Wistar-Kyoto (WKY) rats was compared to SD rats. The WKY rat is an animal model of behavioral inhibition, a risk factor for anxiety, and demonstrates abnormal avoidance learning, marked by facilitated avoidance acquisition and resistance to extinction. The results of the current study indicate that hippocampal damage in SD rats leads to impaired extinction of avoidance learning similar to WKY rats. Furthermore, WKY rats have reduced hippocampal volume and impaired hippocampal synaptic plasticity as compared to SD rats. These results suggest that hippocampal dysfunction enhances the development of persistent avoidance responding and, thus, may confer vulnerability to the development of anxiety disorders and PTSD.

No MeSH data available.


Related in: MedlinePlus