Right hemisphere brain damage impairs strategy updating

Seven RBD patients presented with neglect and although this was associated with greater impairment in strategy updating, there were exceptions: 2 of 7 neglect patients performed above the median of the patient group and 1 of the 6 nonneglect participants was severely impaired.

Although speculative, lesion analyses contrasting high and low performing patients showed that severe impairments were associ-ated with insula and putamen lesions.

Furthermore, we wanted to assess whether updating impairments were separable from the neglect syndrome, a common consequence of right-hemisphere injury with component deficits that could also be characterized as impaired updating of mental models. Patients with right-parietal lesions fail to acquire the second target when the first target is in ipsilesional space and the second appears contralesionally, consistent with a failure to update spatial representations based on the intended actions (Duhamel, Goldberg, et al. In patients with parietal lesions, imagined movements do not conform to Fitts' law such that there is no relationship between the duration of the imagined movements and the factors that would normally modulate actual movements (e.g., target size and distance; Sirigu et al. When the computer exploited the biased play of the monkeys to maximize win rate, the monkeys quickly learned to alter their play indicative of an ability to update current decisions based on the changes to the incoming information.

The most common task used to explore spatial updating is the double-step saccade task. While this work does not speak directly to the neural bases of the ability to update play strategy, the work discussed above, exploring the role of parietal regions such as area LIP in coding expected gain and intention to act, suggests that this is a good candidate region for such a process.

We had 13 right-brain–damaged (RBD) patients and 10 left-brain–damaged (LBD) patients play the children's game “rock, paper, scissors” against a computer opponent that covertly altered its strategy.

Healthy age-matched controls and LBD patients quickly detected extreme departures from uniform play (“paper” chosen on 80% of trials), but the RBD patient group did not.

Participants are required to make sequential eye movements to rapidly extinguished targets (Duhamel, Goldberg, et al. Programming saccades based on retinal coordinates alone leads to an erroneous second saccade. An additional consideration relevant to the competitive games of the ilk of RPS, concerns the ability to infer an opponent's intentions.

On the other hand, as the world is also noisy, we should not “constantly” change our expectations or time, and resources will be wasted chasing our tails (Tenenbaum et al. The cognitive mechanisms and brain structures that are important for decision making are under active study, but while impairments in updating may result in poor decisions, any such impairments would be distinct from a decision making impairment per se. 2001, 2003) also showed that the right-parietal patients were impaired at detecting rapid onsets and offsets of stimuli (i.e., their relative timing). (1997) showed an abnormally large attentional blink in patients with right-parietal lesions such that following a successful detection of one target, the patients (who also had neglect) took 3 times longer than controls to successfully detect a second target.In other words, the term updating implies both the detection of a mismatch between our mental model and collected evidence and the process of revising the mental model based on those mismatches. In other words, processing of the novel event itself may rely on the frontal cortex, but using that information to update mental models may rely more heavily on the parietal cortex (Donchin et al. 2003; for review, see also Herrmann and Knight 2001).The ability to detect novel events or stimuli (i.e., “oddballs”), that would be necessary for prompting the updating of a mental model, has been shown to produce changes to event-related potentials (ERP) that are referred to as a “Novelty P3,” occurring around 300 ms after the event and localized to frontal cortex (Spencer et al. Importantly, a separate P300 component of the ERP, localized to the temporoparietal junction, has been associated with the need to update representations of the environment presumably based, in part, on the information provided by the novel events (Donchin and Coles 1988; Donchin et al. Mental models, as mental simulators of the environment and the sensory consequences of our actions within the environment, provide data useful to the attentional and executive control systems (Norman and Shallice 1986; Baddeley 2007).However, a recent review suggests that no single executive function (e.g., task shifting, inhibition, etc.) can adequately explain the deficits in To M following neurological injury (Aboulafia-Brakha et al. In addition, a recent meta-analysis of functional magnetic resonance imaging (f MRI) studies covering a range of related processes, including the To M, empathy, and a sense of agency (i.e., self as actor), were analyzed and the common region activated across all tasks was shown to be the right temporoparietal junction (Decety and Lamm 2007).Thus, the right-parietal cortex represents a reasonable candidate for generating a mental model of the intentions of an opponent in a competitive game scenario and, as we will argue, for updating that model based on the incoming information.

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