@article {1682, title = {Mean signal and response time influences on multivoxel signals of contextual retrieval in the medial temporal lobe.}, journal = {Brain Behav}, volume = {5}, year = {2015}, month = {2015 Feb}, pages = {e00302}, abstract = {

INTRODUCTION: The medial temporal lobe supports integrating the "what," "where," and "when" of an experience into a unified memory. However, it remains unclear how representations of these contextual features are neurally encoded and distributed across medial temporal lobe subregions.

METHODS: This study conducted functional magnetic resonance imaging of the medial temporal lobe, while participants retrieved pair, spatial, and temporal source memories. Multivoxel classifiers were trained to distinguish between retrieval conditions before and after correction for mean signal and response times, to more thoroughly characterize the multivoxel signal associated with memory context.

RESULTS: Activity in perirhinal and parahippocampal cortex dissociated between memory for associated items and memory for their spatiotemporal context, and hippocampal activity was linked to memory for spatial context. However, perirhinal and hippocampal classifiers were, respectively, driven by effects of mean signal amplitude and task difficulty, whereas the parahippocampal classifier survived correction for these effects.

CONCLUSION: These findings demonstrate dissociable coding mechanisms for episodic memory context across the medial temporal lobe, and further highlight a critical distinction between multivoxel representations driven by spatially distributed activity patterns, and those driven by the regional signal.

}, keywords = {Adult, Brain Mapping, Female, Humans, Magnetic Resonance Imaging, Male, Memory, Photic Stimulation, Temporal Lobe, Young Adult}, issn = {2162-3279}, doi = {10.1002/brb3.302}, author = {Reas, Emilie T and Brewer, James B} } @article {180, title = {Speech-specific tuning of neurons in human superior temporal gyrus.}, journal = {Cereb Cortex}, volume = {24}, year = {2014}, month = {2014 Oct}, pages = {2679-93}, abstract = {

How the brain extracts words from auditory signals is an unanswered question. We recorded approximately 150 single and multi-units from the left anterior superior temporal gyrus of a patient during multiple auditory experiments. Against low background activity, 45\% of units robustly fired to particular spoken words with little or no response to pure tones, noise-vocoded speech, or environmental sounds. Many units were tuned to complex but specific sets of phonemes, which were influenced by local context but invariant to speaker, and suppressed during self-produced speech. The firing of several units to specific visual letters was correlated with their response to the corresponding auditory phonemes, providing the first direct neural evidence for phonological recoding during reading. Maximal decoding of individual phonemes and words identities was attained using firing rates from approximately 5 neurons within 200 ms after word onset. Thus, neurons in human superior temporal gyrus use sparse spatially organized population encoding of complex acoustic-phonetic features to help recognize auditory and visual words.

}, keywords = {Acoustic Stimulation, Adult, Humans, Male, Neurons, Phonetics, Speech Perception, Temporal Lobe}, issn = {1460-2199}, doi = {10.1093/cercor/bht127}, author = {Chan, Alexander M and Dykstra, Andrew R and Jayaram, Vinay and Leonard, Matthew K and Travis, Katherine E and Gygi, Brian and Baker, Janet M and Eskandar, Emad and Hochberg, Leigh R and Halgren, Eric and Cash, Sydney S} } @article {190, title = {Signed words in the congenitally deaf evoke typical late lexicosemantic responses with no early visual responses in left superior temporal cortex.}, journal = {J Neurosci}, volume = {32}, year = {2012}, month = {2012 Jul 11}, pages = {9700-5}, abstract = {

Congenitally deaf individuals receive little or no auditory input, and when raised by deaf parents, they acquire sign as their native and primary language. We asked two questions regarding how the deaf brain in humans adapts to sensory deprivation: (1) is meaning extracted and integrated from signs using the same classical left hemisphere frontotemporal network used for speech in hearing individuals, and (2) in deafness, is superior temporal cortex encompassing primary and secondary auditory regions reorganized to receive and process visual sensory information at short latencies? Using MEG constrained by individual cortical anatomy obtained with MRI, we examined an early time window associated with sensory processing and a late time window associated with lexicosemantic integration. We found that sign in deaf individuals and speech in hearing individuals activate a highly similar left frontotemporal network (including superior temporal regions surrounding auditory cortex) during lexicosemantic processing, but only speech in hearing individuals activates auditory regions during sensory processing. Thus, neural systems dedicated to processing high-level linguistic information are used for processing language regardless of modality or hearing status, and we do not find evidence for rewiring of afferent connections from visual systems to auditory cortex.

}, keywords = {Adolescent, Adult, Brain Mapping, Deafness, Evoked Potentials, Female, Functional Laterality, Humans, Magnetic Fields, Magnetic Resonance Imaging, Magnetoencephalography, Male, Photic Stimulation, Semantics, Sign Language, Temporal Lobe, Time Factors, Young Adult}, issn = {1529-2401}, doi = {10.1523/JNEUROSCI.1002-12.2012}, author = {Leonard, Matthew K and Ferjan Ramirez, Naja and Torres, Christina and Travis, Katherine E and Hatrak, Marla and Mayberry, Rachel I and Halgren, Eric} } @article {187, title = {Auditory modulation of visual apparent motion with short spatial and temporal intervals.}, journal = {J Vis}, volume = {10}, year = {2010}, month = {2010}, pages = {31}, abstract = {

Recently, E. Freeman and J. Driver (2008) reported a cross-modal temporal interaction in which brief sounds drive the perceived direction of visual apparent-motion, an effect they attributed to "temporal capture" of the visual stimuli by the sounds (S. Morein-Zamir, S. Soto-Faraco, \& A. Kingstone, 2003). Freeman and Driver used "long-range" visual motion stimuli, which travel over long spatial and temporal intervals and engage high-order cortical areas (K. G. Claeys, D. T. Lindsey, E. De Schutter, \& G. A. Orban, 2003; Y. Zhuo et al., 2003). We asked whether Freeman and Driver{\textquoteright}s temporal effects extended to the short-range apparent-motion stimuli that engage cortical area MT, a lower-order area with well-established spatiotemporal selectivity for visual motion (e.g. A. Mikami, 1991, 1992; A. Mikami, W. T. Newsome, \& R. H. Wurtz, 1986a, 1986b; W. T. Newsome, A. Mikami, \& R. H. Wurtz, 1986). Consistent with a temporal-capture account, we found that static sounds bias the perception of both the direction (Experiment 1) and the speed (Experiment 2) of short-range motion. Our results suggest that auditory timing may interact with visual spatiotemporal processing as early as cortical area MT. Examination of the neuronal responses of this well-studied area to the stimuli used in this study would provide a test and might provide insight into the neuronal representation of time.

}, keywords = {Acoustic Stimulation, Auditory Perception, Humans, Motion Perception, Photic Stimulation, Temporal Lobe, Time Perception, Visual Cortex}, issn = {1534-7362}, doi = {10.1167/10.12.31}, author = {Kafaligonul, Hulusi and Stoner, Gene R} }