Abstract
The startle response is composed by a set of reflex behaviors intended to prepare the organism to face a potentially relevant stimulus. This response can be modulated by several factors as, for example, repeated presentations of the stimulus (startle habituation), or by previous presentation of a weak stimulus (Prepulse Inhibition [PPI]). Both phenomena appear disrupted in schizophrenia that is thought to reflect an alteration in dopaminergic and glutamatergic neurotransmission. In this paper we analyze whether the reported deficits are indicating a transient effect restricted to the acute phase of the disease, or if it reflects a more general biomarker or endophenotype of the disorder. To this end, we measured startle responses in the same set of thirteen schizophrenia patients with a cross-sectional design at two periods: 5 days after hospital admission and 3 months after discharge. The results showed that both startle habituation and PPI were impaired in the schizophrenia patients at the acute stage as compared to a control group composed by 13 healthy participants, and that PPI but not startle habituation remained disrupted when registered 3 months after the discharge. These data point to the consideration of PPI, but not startle habituation, as a schizophrenia biomarker.
Highlights
The information processing that is carried out by organisms with complex nervous systems begins with a set of automatic processes of a preattentional nature that usually occur during the first 100 ms after the onset of the stimuli (Ellenbroek, 2004)
Taken with caution due to the small sample size1, the analyses that compare the results of healthy control participants with those obtained in acute schizophrenia patients have revealed significant differences in both habituation of the startle response and intensity of Prepulse Inhibition (PPI)
With regard to the results reported in schizophrenia patients 3 months after discharge, once the symptoms had decreased, a recovery of the process of habituation of the startle response was observed, while the impairment in PPI remained unchanged from that recorded in the acute stage of the disease
Summary
The information processing that is carried out by organisms with complex nervous systems begins with a set of automatic processes of a preattentional nature that usually occur during the first 100 ms after the onset of the stimuli (Ellenbroek, 2004). These processes trigger various response mechanisms, one category of which is the startle response, a neuronal mechanism related to attention that varies along a continuum from deep sleep to intense excitement (Dawson et al, 1999). For example, the startle response increases when the organism is in a state of emotional activation
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