Neuronal Correlates of Small Animal Phobia in Human Subjects through fMRI: The Role of the Number and Proximity of Stimuli

Abstract

Brain regions involved in small-animal phobia include subcortical and cortical areas. The present study explored the neuronal correlates of small-animal phobia through fMRI data to determine whether a manipulation of number and proximity parameters affects the neurobiology of the processing of feared stimuli. The participants were 40 individuals with phobia and 40 individuals without phobia (28.7% male and 71.3% female). They watched videos of real and virtual images of spiders, cockroaches and lizards in motion presented more or less nearby with one or three stimuli in the different conditions. The results suggested a differential brain activity between participants with and without phobia depending on the proximity and number of phobic stimuli. Proximity activated the motor response marked by the precentral gyrus and the cingulate gyrus. By contrast, the number of stimuli was associated with significant sensory activity in the postcentral gyrus and ventromedial prefrontal cortex. We also observed a greater activity in the occipital cortex when exploring the number compared to the proximity factor. Threatening stimuli presented nearby and those presented in greater numbers generated an intense phobic response, suggesting a different emotion regulation strategy. Based on these findings, exposure therapies might consider including proximity to the threat and number of stimuli as key factors in treatment.

Virtual reality in the diagnostic and therapy for mental disorders: A systematic review

“…The third study (Petrescu et al, 2020), in turn, found that anxiety levels during height exposure may be predicted using features extracted from heart rate and skin conductance measurements. A series of fMRI studies in small animal phobia showed that VR exposure leads to activations of fear-related brain areas (Clemente et al, 2014), that the intensity of brain activation and number of structures involved is higher in phobics than HC (Fumero et al, 2021), that 3D animated animal stimuli (spiders, lizards, cockroaches) elicit anatomically-similar (but weaker) brain activations as photorealistic 3D videos showing the same animals in persons with SP (Peñate et al, 2019), and that a higher number and greater proximity of fear related stimuli increases the neuronal phobic response (Fumero et al, 2021).…”

Neuronal Activity during Exposure to Specific Phobia through fMRI: Comparing Therapeutic Components of Cognitive Behavioral Therapy

“…Different therapeutic components of CBT may activate different neural substrates, which would indicate that there is more than one mechanism explaining CBT efficacy. Some studies suggest that exposure to phobic stimuli can be altered by contextual conditions, such as proximity to stimuli or real or virtual images [ 15 , 21 ]. These different conditions imply changes in brain activation or deactivation areas and in turn affect CBT efficacy [ 22 ].…”

A Voxel-Based Morphometric Study of Gray Matter in Specific Phobia

“…In fact, common and specific factors have been identified with the various diagnoses related to anxiety to the extent that different features of the phobic stimulus activate different brain areas. Thus, stimuli presenting near activated areas were associated with a motor response, whereas a greater number of phobic stimuli activated sensory areas [ 15 ], suggesting a different emotion regulation strategy.…”