Non-identical neural mechanisms for two types of mental transformation: event-related potentials during mental rotation and mental paper folding

Abstract

Reaction times, accuracy and 128-channel event-related potentials (ERPs) were measured from 14 normal, right-handed subjects while they performed two different parity-judgment tasks that require transformations of mental images: a relatively simple task requiring a single transformation (mental letter rotation), and a more complex task involving a coordinated sequence of transformations (mental paper folding). Reaction times increased monotonically with larger angular displacements from the upright (for mental rotation) and with number of squares carried (for mental paper folding). Both the tasks resulted in amplitude modulation of an approximately 420-700 ms latency ERP component at parietal electrodes. Scalp topographies indicated that right parietal cortex was activated during mental rotation, but bilateral parietal regions were activated during mental paper folding. Our results support the notion of a right hemispheric superiority for tasks involving simple, single mental rotations, but indicate greater involvement of the left hemisphere when a more complex sequence of transformations are required. This task-dependent lability of hemispheric function may account for some of the inconsistent results reported by previous neuroimaging and electrophysiological studies.

Linking Out-of-Body Experience and Self Processing to Mental Own-Body Imagery at the Temporoparietal Junction

“…1997; Milivojevic et al, 2003). These latter neural mechanisms classically are observed at a somewhat later time period of 450 -700 ms in the region of the IPS (Pegna et al, 1997;Harris et al, 2000;Jordan et al, 2001;Gauthier et al, 2002;Podzebenko et al, 2002;Harris and Miniussi, 2003) as also supported by our present findings.…”

“…Furthermore, because our evoked potential study showed OBTrelated activity at ϳ350 ms and previous studies revealed that mental transformation of objects takes place between ϳ400 and 600 ms after stimulus onset (Pegna et al, 1997;Milivojevic et al, 2003), we expected TMS pulses to interfere with mental transformations at these latencies and therefore collapsed the data for the SOAs of 100 -300, 350 -550, and 600 -800 ms (each time window consisting of 5 time bins). These data were subjected to repeated measure ANOVAs, with the factors TMS site (TPJ vs IPS), task (OBT vs LT), stimulus orientation (back-facing/unturned vs front-facing/turned), and SOA (100 -300/350 -550/600 -800 ms).…”

“…To investigate further the implication of the TPJ in processes of mental OBTs, we designed a TMS experiment to examine whether the observed brain activation pattern at the TPJ indeed was required and selective for the mental transformation of one's body and visuospatial perspective or whether it might be related to a more general mental transformation mechanism, i.e., mental transformation of external objects without change in observer's position and visuospatial perspective (Kosslyn, 1994;Pegna et al, 1997;Milivojevic et al, 2003). For this we applied single TMS pulses over the TPJ (test site) and the IPS (control site) in healthy participants (who had never experienced an OBE) while performing the OBT task or the LT task (Fig.…”

Dissociation of subtraction and multiplication in the right parietal cortex: Evidence from intraoperative cortical electrostimulation

“…An event-related potentials study showed that, in comparison with multiplication, addition elicited smaller late positive potentials at the right posterior electrodes (Zhou et al, 2009). The smaller late positive potentials have been linked to greater visuospatial processing in previous ERP studies (e.g., Heil & Rolke, 2002;Milivojevic et al, 2003;Núñez-Peña et al, 2005;Yoshino et al, 2000). To our knowledge, the dissociation between subtraction and multiplication at the right parietal cortex has been reported only in one previous neuropsychological study (e.g., Dehaene & Cohen, 1997).…”

Three sequential brain activations encode mental transformations of upright and inverted human bodies: A high resolution evoked potential study

“…These revealed an activation of parietal cortex, either exclusively in the right hemisphere (Harris et al, 2000;Harris and Miniussi, 2003), the left hemisphere (Alivisatos and Petrides, 1997; Vingerhoets et al, 2001), or bilaterally (Carpenter et al, 1999). Studies measuring event-related potentials (ERPs) during the mental transformation of external objects revealed a negative component located over parietal scalp electrodes (Peronnet and Farah, 1989;Wijers et al, 1989;Yoshino et al, 2000;Milivojevic et al, 2003). Using evoked potential mapping (EP mapping) and electrical neuroimaging, Pegna et al (1997) found a topographic pattern (or EP map) between 400 and 600 ms that increased in duration for greater angles of rotation and was localized to right parieto-occipital cortex.…”