Negative learning bias is associated with risk aversion in a genetic animal model of depression

Abstract

The lateral habenula (LHb) is activated by aversive stimuli and the omission of reward, inhibited by rewarding stimuli and is hyperactive in helpless rats—an animal model of depression. Here we test the hypothesis that congenital learned helpless (cLH) rats are more sensitive to decreases in reward size and/or less sensitive to increases in reward than wild-type (WT) control rats. Consistent with the hypothesis, we found that cLH rats were slower to switch preference between two responses after a small upshift in reward size on one of the responses but faster to switch their preference after a small downshift in reward size. cLH rats were also more risk-averse than WT rats—they chose a response delivering a constant amount of reward (“safe” response) more often than a response delivering a variable amount of reward (“risky” response) compared to WT rats. Interestingly, the level of bias toward negative events was associated with the rat's level of risk aversion when compared across individual rats. cLH rats also showed impaired appetitive Pavlovian conditioning but more accurate responding in a two-choice sensory discrimination task. These results are consistent with a negative learning bias and risk aversion in cLH rats, suggesting abnormal processing of rewarding and aversive events in the LHb of cLH rats.

Areas activated during naturalistic reading comprehension overlap topological visual, auditory, and somatotomotor maps

“…In FEF, while the activation disappears in Hindi vs. Dot contrast, a good part of it is still highly significant in English vs. Hindi contrast, suggesting that the FEF may have a larger role in comprehension, an observation supported by other studies [Choi et al, 2014; Hasson et al, 2008]. …”

“…The pattern of activations for the reading experiment across the whole cortex is similar to what was found in a recent natural reading experiment reported by Choi et al [2014]. Compared to Choi et al, our study utilized controlled/matched saccades as opposed to free eye movements, and a higher resolution, fully surface‐based analysis stream as opposed to a volume‐based cross‐subject analysis only mapped to an average surface at the end.…”

Evidencing a place for the hippocampus within the core scene processing network

“…In terms of RSC, both the animal and human literature indicates that RSC is an important brain region for spatial navigation [Byrne et al, 2007; Epstein and Vass, 2014; Knight and Hayman, 2014; Kravitz et al, 2011b; Vann et al, 2009]. As such, RSC responses have been shown to attenuate across multiple views of the same scene, suggesting that this region maintains information about the local environment across visual transformations [Marchette et al, 2014; Park and Chun, 2009].…”

“…Also, while the one‐back localiser task was sufficient to identify significant RSC voxels in individual brains, particularly at lower voxel‐wise thresholds, it is not necessarily attuned to the precise function of this brain region in scene processing (i.e., spatial navigation), which could account for the reduced inter‐individual consistency found here. In addition, there are inconsistencies in the field when defining the RSC [Knight and Hayman, 2014; Vann et al, 2009], to the extent that some researchers have restricted analysis to anatomical boundaries [Auger and Maguire, 2013], whereas others use the more liberal, and functionally‐defined retrosplenial complex [Bar and Aminoff, 2003; Epstein et al, 2007]. …”

Intuitive decision making as a gradual process: investigating semantic intuition‐based and priming‐based decisions with fMRI

“…This model may be related to the idea that unconscious thought organizes information. For instance, Ritter and Dijskterhuis (2014), recently proposed, based on their empirical findings, that representations become better organized and more polarized, and that memory becomes more gist‐based, during an unconscious thought period (i.e., in an incubation period). Their results may suggest that unconscious thought is a process wherein disorganized information becomes more and more organized until some kind of threshold is reached and conclusions can be transferred to consciousness.…”