Memory retrieval is typically a goal-directed behavior, and as such, potentially influenced by reinforcement and motivation processes. Although striatal activation is often evident during memory retrieval, its functional significance remains unclear because typical memory paradigms do not control the motivational significance of memory decisions. We used event-related functional magnetic resonance imaging (fMRI) to investigate striatal activation during recognition with and without performance-linked monetary incentives. During initial performance in the absence of incentives, dorsal striatal activation for “Old” memory conclusions nonetheless exceeded that for “New” conclusions regardless of the accuracy of these conclusions. In contrast, subsequent scans paired incentives with either “Old” or “New” conclusions and demonstrated greater activation for whichever judgment was potentially rewarded, both with and without performance feedback. The data demonstrate that striatal activation during recognition judgments does not signal monetary reward receipt, cognitive feedback, or successful episodic retrieval. Instead, it is heavily dependent upon satisfaction of the subjective goals of the observer.
Activation in frontopolar cortex (FPC; BA 10) has been associated both with attending to mental states and with integrating multiple mental relations. However, few previous studies have manipulated both of these cognitive processes, precluding a clear functional distinction among regions within FPC. To address this issue, we developed an fMRI task that combined mentalizing and relational integration processes. Participants saw blocks of single words and performed one of three judgments: how pleasant or unpleasant they found each word ( Self condition), how a specific friend would evaluate the pleasantness of the word ( Other condition), or the difference between their own pleasantness judgment and that of their friend ( Relational condition). We found that medial FPC was modulated by Other relative to Self judgments, consistent with a role in mentalizing. Lateral FPC was significantly activated during Relational compared to Self judgements, suggesting that this region is particularly involved in relational integration. The results point to a strong functional dissociation between medial and lateral FPC. In addition, the data demonstrate a role for lateral FPC in the social domain, provided that the task requires the integration of one’s preferences with those of others.
12 February 2018 in Applied Neuropsychology: Adult
There is a minimal amount of knowledge regarding the cognitive abilities of people with aphasia. We evaluated the performance of individuals with chronic aphasia (AP) and control participants without aphasia (CP) with left hemisphere stroke in a battery of nonverbal cognitive tests and its relationship with aphasia severity, comprehension abilities, and speech fluency in a prospective cross-sectional study. Cognitive evaluation comprised 10 nonverbal tests. Scores were converted to age and education adjusted standard scores. Forty-eight AP and 32 CP were included. AP average scores were below normal range in three tests: Camel and Cactus Test, immediate recall of 5 Objects Test and Spatial Span. The mean test scores were significantly lower in AP than in CP, except in four tests. Aphasia severity and verbal comprehension ability correlated significantly with semantic memory, constructive abilities and attention/processing speed tests. Subjects with nonfluent aphasia had lower scores than CP in memory, executive functions and attention tests, while subjects with fluent aphasia showed lower scores in memory tests only. On average half of the individuals with aphasia exhibit results within the normal range. Nonetheless, their performance was worse than that of controls, despite the fact that many tests do not correlate with the severity of language disorder.