Reduced habituation in patients with schizophrenia

Abstract

Background Neural habituation, the decrease in brain response to repeated stimulation, is a basic form of learning. There is strong evidence for behavioral and physiological habituation deficits in schizophrenia, and one previous study found reduced neural habituation within the hippocampus. However, it is unknown whether neural habituation deficits are specific to faces and limited to the hippocampus. Here we studied habituation of several brain regions in schizophrenia, using both face and object stimuli. Post-scan memory measures were administered to test for a link between hippocampal habituation and memory performance. Methods During an fMRI scan, 23 patients with schizophrenia and 21 control subjects viewed blocks of a repeated neutral face or neutral object, and blocks of different neutral faces and neutral objects. Habituation in the hippocampus, primary visual cortex and fusiform face area (FFA) was compared between groups. Memory for faces, words, and word pairs was assessed after the scan. Results Patients showed reduced habituation to faces in the hippocampus and primary visual cortex, but not the FFA. Healthy control subjects exhibited a pattern of hippocampal discrimination that distinguished between repeated and different images for both faces and objects, and schizophrenia patients did not. Hippocampal discrimination was positively correlated with memory for word pairs. Conclusion Patients with schizophrenia showed reduced habituation of the hippocampus and visual cortex, and a lack of neural discrimination between old and new images in the hippocampus. Hippocampal discrimination correlated with memory performance, suggesting reduced habituation may contribute to the memory deficits commonly observed in schizophrenia.

Neural correlates of out-group bias predict social impairment in patients with schizophrenia

“…In the schizophrenia group we found two patterns that distinguished patients with low social impairment from patients with high social impairment. The low social impairment group was characterized by an initial delay followed by sustained activation of the amygdala, hippocampus, and visual cortex, consistent with a heightened social perception of threat (Green and Phillips, 2004) and the failure to habituate observed in previous studies (Holt et al, 2005; Williams et al, 2013). In contrast, the high social impairment group was characterized by a failure to respond to opposite-gender, faces even after 120 face presentations.…”

“…However, emotional faces confound emotion processing with processing of the social information inherent in faces. To directly investigate neural processing of a socially relevant stimulus in patients with schizophrenia, we recently measured neural response to repeated presentation of neutral faces (Williams et al, 2013). …”

Inflammation Effects on Motivation and Motor Activity: Role of Dopamine

“…To date, the most reliable decreases in ventral striatal activity have been observed during periods of reward anticipation (for a recent meta-analysis, see Radua et al, 2015), which have also been linked to reduced effortful behavior in schizophrenia (Wolf et al, 2014). In addition, recent work has demonstrated both a blunting of neural prediction errors to contextually relevant cues (Morris et al, 2011) as well as behavioral evidence for enhanced prediction error learning for irrelevant stimuli (Hannestad et al, 2012b;Williams et al, 2013). These findings are consistent with predictions from the aberrant salience hypothesis, which predicts that both positive and negative symptoms are linked to irregular striatal DA systems that may fail to appropriately respond to meaningful reward incentives (Winton-Brown et al, 2014).…”

Clozapine and glycinamide prevent MK-801-induced deficits in the novel object recognition (NOR) test in the domestic rabbit (Oryctolagus cuniculus)

“…We argue that this mechanism may be distinct from the case of the rodent NOR test, where slowly decaying (up to 24 h) episodic-like memory appears to operate [14] (but for alternative interpretations, see [69]). A model that potentially involves alterations in primary sensory processing could be useful for modeling deficits in "bottom-up" processes that have been described in schizophrenics, including deficits in habituation and automatic responses to novelty [10,27,43,45,65]. Some of these sensory processing deficits have been strongly associated with negative symptom scores [10,13,27,68].…”