The Behavioural Inhibition System, anxiety and hippocampal volume in a non-clinical population

Liat Levita,Andrew Healey,Evelina Papakonstantinou,Catherine Bois,Emily Smyllie,Colin Lever,Tom Hartley

doi:10.1186/2045-5380-4-4

Abstract

BackgroundAnimal studies have suggested that the hippocampus may play an important role in anxiety as part of the Behavioural Inhibition System (BIS), which mediates reactivity to threat and punishment and can predict an individual’s response to anxiety-relevant cues in a given environment. The aim of the present structural magnetic resonance imaging (MRI) study was to examine the relationship between individual differences in BIS and hippocampal structure, since this has not received sufficient attention in non-clinical populations. Thirty healthy right-handed participants with no history of alcohol or drug abuse, neurological or psychiatric disorders, or traumatic brain injury were recruited (16 male, 14 female, age 18 to 32 years). T1-weighted structural MRI scans were used to derive estimates of total intracranial volume, and hippocampal and amygdala gray matter volume using FreeSurfer. To relate brain structure to Gray’s BIS, participants completed the Sensitivity to Punishment questionnaire. They also completed questionnaires assessing other measures potentially associated with hippocampal volume (Beck Depression Inventory, Negative Life Experience Survey), and two other measures of anxiety (Spielberger Trait Anxiety Inventory and the Beck Anxiety Inventory).ResultsWe found that high scores on the Sensitivity to Punishment scale were positively associated with hippocampal volume, and that this phenomenon was lateralized to the right side. In other words, greater levels of behavioural inhibition (BIS) were positively associated with right hippocampal volume.ConclusionsOur data suggest that hippocampal volume is related to the cognitive and affective dimensions of anxiety indexed by the Sensitivity to Punishment, and support the idea that morphological differences in the hippocampal formation may be associated with behavioural inhibition contributions to anxiety.

Highlights

Animal studies have suggested that the hippocampus may play an important role in anxiety as part of the Behavioural Inhibition System (BIS), which mediates reactivity to threat and punishment and can predict an individual’s response to anxiety-relevant cues in a given environment
Sensitivity to Punishment was not significantly correlated with either left hippocampal or amygdala volumes When we replaced the volume of the right hippocampus in the multiple regression analysis with the volume of the left hippocampus or either the left or right amygdala, again controlling for known associations of age, sex, and intracranial volume (ICV), we found no relationship between these regions and StP (Additional file 2: Table S2)
No significant relationship between hippocampal volume and other anxiety constructs our focus was on the animal literature-based behavioural inhibition approach to anxiety conceptualised by Gray, and implemented through the StP instrument of Torrubia and colleagues [16], we examined whether the relationship observed between right hippocampal volume and StP was specific to the BIS construct of anxiety, or whether a similar relationship existed for other constructs of anxiety

Summary

Introduction

Animal studies have suggested that the hippocampus may play an important role in anxiety as part of the Behavioural Inhibition System (BIS), which mediates reactivity to threat and punishment and can predict an individual’s response to anxiety-relevant cues in a given environment. Lang’s tripartite model of anxiety suggests that it consists of three response domains: cognitive, behavioural, and physiological [1], which together result in a state of apprehensive worry, hyperarousal to threat cues, avoidance behaviours and negatively-biased cognitions [2]. Each of these domains is suggested to measure a separate element of response characteristics and potentially independent underlying mechanisms to the construct of anxiety [3]. We recently showed that Gray and McNaughton’s central observation extends to the awake, freely moving rat, where anxiolytic drugs reduce the frequency of natural theta obtained during locomotion [14]

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