Development and validation of the Temporal Order Memory Assessment for Brain Imaging (TOMABI): Evidence of prefrontal cortex involvement in memory for temporal context

Human and animal lesion studies suggest that memory for temporal context is anatomically dissociable from memory for content: the dorsolateral prefrontal cortex appears necessary for when but not what memory and medial temporal lobe regions seem necessary for what but not when memory. However, the implications of these results for the functioning of the healthy human are in doubt for many reasons, including: uncertainty about brain homology between humans and other species, concerns about long-standing or injury-related structural reorganization in pathological populations, difficulty distinguishing damage to a cognitive center from disruption of a pathway, and trouble disentangling deficits at encoding, storage, or retrieval. Thus, in the present investigation, neurobehavioral probes were developed and used in conjunction with functional magnetic resonance imaging (fMRI) to study the hypothesis that content and context retrieval are dissociable in healthy individuals. A test of verbal recognition and recency judgment, the Temporal Order Memory Assessment for Brain Imaging (TOMABI), was created and shown to have adequate reliability. Functional neuroimaging revealed significant activation in left area 19 during recognition memory, and demonstrated increased blood flow in bilateral dorsolateral prefrontal cortex, midline supplementary motor cortex and left precuneus during recency judgments. The TOMABI2, a test of verbal recognition and list discrimination, also was shown to have adequate reliability and psychometric validity. Patients with frontal lesions performed no poorer than age-matched controls on either subtest, although this likely was due to an imperfect patient sample and/or age-related floor effects in the control group. Direct comparison of blood flow during list discrimination and recognition using fMRI revealed no unique areas of activation. Follow-up investigations demonstrated that each task was associated with similar activation: significant blood flow increases compared to a sensori-motor control task were seen in prefrontal and anterior cingulate regions. These results are inconsistent with the hypothesis that recall of content and context involve dissociable brain regions. Instead, they suggest that both types of retrieval are associated with similar brain activation, especially in prefrontal cortex. Future work should clarify the nature of any overlapping cognitive processes and determine the specificity of this functional similarity to the retrieval phase of memory

Development and validation of the Temporal Order Memory Assessment for Brain Imaging (TOMABI): Evidence of prefrontal cortex involvement in memory for temporal context

Human and animal lesion studies suggest that memory for temporal context is anatomically dissociable from memory for content: the dorsolateral prefrontal cortex appears necessary for when but not what memory and medial temporal lobe regions seem necessary for what but not when memory. However, the implications of these results for the functioning of the healthy human are in doubt for many reasons, including: uncertainty about brain homology between humans and other species, concerns about long-standing or injury-related structural reorganization in pathological populations, difficulty distinguishing damage to a cognitive center from disruption of a pathway, and trouble disentangling deficits at encoding, storage, or retrieval. Thus, in the present investigation, neurobehavioral probes were developed and used in conjunction with functional magnetic resonance imaging (fMRI) to study the hypothesis that content and context retrieval are dissociable in healthy individuals. A test of verbal recognition and recency judgment, the Temporal Order Memory Assessment for Brain Imaging (TOMABI), was created and shown to have adequate reliability. Functional neuroimaging revealed significant activation in left area 19 during recognition memory, and demonstrated increased blood flow in bilateral dorsolateral prefrontal cortex, midline supplementary motor cortex and left precuneus during recency judgments. The TOMABI2, a test of verbal recognition and list discrimination, also was shown to have adequate reliability and psychometric validity. Patients with frontal lesions performed no poorer than age-matched controls on either subtest, although this likely was due to an imperfect patient sample and/or age-related floor effects in the control group. Direct comparison of blood flow during list discrimination and recognition using fMRI revealed no unique areas of activation. Follow-up investigations demonstrated that each task was associated with similar activation: significant blood flow increases compared to a sensori-motor control task were seen in prefrontal and anterior cingulate regions. These results are inconsistent with the hypothesis that recall of content and context involve dissociable brain regions. Instead, they suggest that both types of retrieval are associated with similar brain activation, especially in prefrontal cortex. Future work should clarify the nature of any overlapping cognitive processes and determine the specificity of this functional similarity to the retrieval phase of memory