Dissociable Mechanisms of Attentional Control within the Human Prefrontal Cortex

Abstract

Neuropsychological tests that require shifting an attentional set, such as the Wisconsin Card Sorting Test, are sensitive to frontal lobe damage. Although little information is available for humans, an animal experiment suggested that different regions of the prefrontal cortex may contribute to set shifting behavior at different levels of processing. Behavioral studies also suggest that set shifting trials are more time consuming than non-set shifting trials (i.e. switch cost) and that this may be underpinned by differences at the neural level. We determined whether there were differential neural responses associated with two different levels of shifting behavior, that of reversal of stimulus-response associations within a perceptual dimension or that of shifting an attentional set between different perceptual dimensions. Neural activity in the antero-dorsal prefrontal cortex increased only in attentional set shifting, in which switch costs were significant. Activity in the postero-ventral prefrontal cortex increased not only in set shifting but also in reversing stimulus-response associations, in which switch costs were absent. We conclude that these distinct regions in the human prefrontal cortex provide different levels of attention control in response selection. Thus, the antero-dorsal prefrontal cortex may be critical for higher order control of attention, i.e. attentional set shifting, whereas the postero-ventral area may be related to a lower level of shift, i.e. reorganizing stimulus-response associations.

Dissociable brain mechanisms for inhibitory control: effects of interference content and working memory capacity

“…The present left inferior frontal activation was located more posterior at the junction of the precentral sulcus and the inferior frontal sulcus. Activation in this postero-ventral PFC region has been reported in a variety of tasks with rather different processing demands, including active maintenance [29], set shifting [10,35] or task preparation [3]. A common characteristic of these tasks is the requirement to learn new stimulus-response associations and to adapt them to current task demands [35].…”

“…Activation in this postero-ventral PFC region has been reported in a variety of tasks with rather different processing demands, including active maintenance [29], set shifting [10,35] or task preparation [3]. A common characteristic of these tasks is the requirement to learn new stimulus-response associations and to adapt them to current task demands [35]. In fact, experimental lesion studies in animals showed that lesions in this area impair the relearning of stimulus-response and stimulus -reward associations [35,39] showed that activation in the postero-ventral PFC was not only enhanced in a set shifting task in which participants had to switch back and forth between a color and a shape matching task but also in a so-called reversal task in which only stimulus-response mappings were reversed.…”

“…A common characteristic of these tasks is the requirement to learn new stimulus-response associations and to adapt them to current task demands [35]. In fact, experimental lesion studies in animals showed that lesions in this area impair the relearning of stimulus-response and stimulus -reward associations [35,39] showed that activation in the postero-ventral PFC was not only enhanced in a set shifting task in which participants had to switch back and forth between a color and a shape matching task but also in a so-called reversal task in which only stimulus-response mappings were reversed. This indicates that the postero-ventral PFC houses more general task management functions; best described as the reorganisation of stimulus-response assignments in the service of goal-directed behavior.…”

“…letters) in item recognition tasks activated left PFC regions [5,9,22] that are also activated when verbal materials have to be actively maintained in working memory. Conversely, right PFC areas were implicated in a variety of interference resolution processes with different informational contents, like letters [5,18,32] or familiar and unfamiliar objects [25,35].…”

Reduced brain connectivity and mental flexibility in mild traumatic brain injury

“…Mental in flexibility is one of the cognitive complaints experienced in mTBI14 and manifests as a tendency to perseverate or “become stuck.” The neural underpinnings of mental flexibility have been well studied using the Wisconsin Card Sort Task,29 and areas in prefrontal, frontal, and posterior cortical regions have been implicated using both fMRI30, 31, 32, 33, 34, 35, 36 and MEG 37, 38, 39. Our group has designed a simpler task aimed at probing the core “shifting” aspect of mental flexibility and we have optimized this for MEG 40…”