We demonstrate that spatially accurate and selective stimulation is crucial when cortical functions are studied by the creation of temporary lesions with transcranial magnetic stimulation (TMS). Previously, the interpretation of the TMS results has been hampered by inaccurate knowledge of the site and strength of the induced electric current in the brain. With a Navigated Brain Stimulation (NBS) system, which provides real-time magnetic resonance image (MRI)-guided targeting of the TMS-induced electric field, we found that TMS of a spatially restricted cortical S1 thenar area is sufficient to abolish sensation from a weak electric stimulation of the corresponding skin area. We demonstrate that with real-time navigation, TMS can be repeatably directed at millimeter-level precision to a target area defined on the MRI. The stimulation effect was temporally and spatially specific: the greatest inhibition of sensation occurred when TMS was applied 20 ms after the cutaneous test stimulus and the TMS effect was sensitive to 8-13 mm displacements of the induced electric field pattern. The results also indicate that TMS selectively to S1 is sufficient to abolish perception of cutaneous stimulation of the corresponding skin area.

We studied the influence of temporal parameters on localization of monofilament-evoked touch versus thulium laser-induced and C fiber-mediated pain in human subjects. Stimuli were applied at interstimulus intervals (ISIs) varying from 1 to 9 s to determine discrimination between successive stimulus sites in the palmar skin. Localization threshold was about two times higher for heat pain than touch. The localization threshold for pain, but not touch, decreased with prolongation of the ISI from 1 to 7-9 s, and it remained higher for pain even at the ISI of 9 s. The response time was longer for pain than touch, and it increased with an increase in the ISI, independent of the modality. Discriminative capacity, as assessed by the receiver operating characteristics curve, was markedly better for touch than pain. The discriminative capacity decreased with an increase of the ISI, but only for touch. The results indicate that localization is more accurate for touch than pain. Temporal summation of C fiber-evoked pain contributes to the reduced accuracy of pain localization if the ISI is < or = 3 s. Additionally, temporal factors dissociatively influence the response strategy in the tactile versus pain localization task with the prolongation of the ISI from 1 to 9 s. Due to this strategy change, localization threshold for touch remains constant at prolonged ISIs, in spite of a decrease in discriminative capacity. In a cutaneous localization task, the subject's accuracy and response strategy vary with the modality and temporal parameters of sequential test stimulation.

Memory judgement processes, based on the characteristics and associations of retrieved memories such as sensory details and supporting memories, are considered as important as retrieval in several autobiographical memory models. Judgement processes have received less research attention than memory characteristics themselves. The present studies examined memory judgement using qualitative analysis of the reasons participants gave for confidence in retrieved childhood memories. For memories they were confident of, participants cited memory phenomenology, especially sensory and affective details, much more frequently than consistency with other autobiographical knowledge. For memories they were not confident of, participants reported lack of consistency with autobiographical knowledge or with others' memories more often than memory phenomenology as reasons for their uncertainty. Participants' comments also revealed several metacognitive beliefs about the relationship between memory characteristics and accuracy. These data are consistent with two-process models of memory judgement associated with true versus false memories.

It is recommended that performance validity be assessed in all neuropsychological cases involving external incentive. The present study sought to develop an embedded performance validity measure based on the Spatial Span task of the Wechsler Memory Scale-III in a sample of litigating persistent postconcussion complainants. The Reliable Spatial Span (RSS) calculation had specificity, sensitivity, and predictive power values within the range of other embedded measures. This finding suggests that RSS is able to distinguish between persistent postconcussion complainants demonstrating valid and invalid performance. Other calculations involving Spatial Span scores had lower classification accuracy. Reliable Digit Span (RDS) classification accuracy within the present sample was lower than that of previous research, as well as of RSS. Potential reasons for lack of RDS replication are discussed, along with the potential use of RSS as an embedded validity performance indicator.

The present study sought to determine whether cognitive outcome and course of recovery in civilian penetrating brain injury due to gunshot can be distinguished from that of non-penetrating brain injury due to motor vehicle accident. Matched survivors of penetrating and non-penetrating brain injury were assessed with a brief neuropsychological test battery at inpatient rehabilitation, 1 year post-injury, and 2 years post-injury. The traumatic brain injury groups were found to have patterns of performance marked by reliably distinct differences in isolated areas, with different cognitive predictors of brain injury type present in early versus later recovery. The degree of recovery over the first 2 years appeared to be quite similar for penetrating and non-penetrating injuries.