Biology subjects

Wood, K. C.

Publications and source records attributed to Wood, K. C..

4 recordsLinked to original sources

bioRxiv2018

Primary auditory cortex represents the location of sound sources in a cue-invariant manner

Auditory cortex is required for sound localisation, but how neural firing in auditory cortex underlies our perception of sources in space remains unknown. We measured spatial receptive fields in animals actively attending to spatial location while they performed a relative localisation task using stimuli that varied in the spatial cues that they provided. Manipulating the availability of binaural and spectral localisation cues had mild effects on the ferrets performance and little impact on the spatial tuning of neurons in primary auditory cortex (A1). Consistent with a representation of space, a subpopulation of neurons encoded spatial position across localisation cue types. Spatial receptive fields measured in the presence of a competing sound source were sharper than those measured in a single-source configuration. Together these observations suggest that A1 encodes the location of auditory objects as opposed to spatial cue values. We compared our data to predictions generated from two theories about how space is represented in auditory cortex: The two-channel model, where location is encoded by the relative activity in each hemisphere, and the labelled-line model where location is represented by the activity pattern of individual cells. The representation of sound location in A1 was mainly contralateral but peak firing rates were distributed across the hemifield consistent with a labelled line model in each hemisphere representing contralateral space. Comparing reconstructions of sound location from neural activity, we found that a labelled line architecture far outperformed two channel systems. Reconstruction ability increased with increasing channel number, saturating at around 20 channels.\n\nSignificance statementOur perception of a sound scene is one of distinct sound sources each of which can be localised, yet auditory space must be computed from sound location cues that arise principally by comparing the sound at the two ears. Here we ask: (1) do individual neurons in auditory cortex represent space, or sound localisation cues? (2) How is neural activity read out for spatial perception? We recorded from auditory cortex in ferrets performing a localisation task and describe a subpopulation of neurons that represent space across localisation cues. Our data are consistent with auditory space being read out using the pattern of activity across neurons (a labelled line) rather than by averaging activity within each hemisphere (a two-channel model).

neuroscience↗

bioRxiv2018

Label propagation defines signaling networks associated with recurrently mutated cancer genes

Each different tumor type has a distinct profile of genomic perturbations and each of these alterations causes unique changes to cellular homeostasis. Detailed analyses of these changes would reveal downstream effects of genomic alterations, contributing to our understanding of their roles in tumor development and progression. Across a range of tumor types, including bladder, lung, and endometrial carcinoma, we determined genes that are frequently altered in The Cancer Genome Atlas patient populations to study the effects of these alterations on signaling and regulatory pathways. To achieve this, we used a label propagation-based methodology to generate networks from gene expression signatures of mutations. Individual networks offered a comprehensive view of signaling changes represented by gene signatures, which in turn reflect the scope of molecular events that are perturbed in the presence of a given genomic alteration. Comparing different networks to each other revealed commonalities between them and biological pathways distinct genomic alterations converge on, highlighting the critical signaling events tumor dysregulate through multiple mechanisms. Finally, mutations inducing common changes to the signaling network were used to search for genomic markers of drug response, connecting shared perturbations to differential drug response.

bioinformatics↗

bioRxiv2018

Multisensory stimuli improve relative localisation judgments compared to unisensory auditory or visual stimuli

Observers performed a relative localisation task in which they reported whether the second of two sequentially presented signals occurred to the left or right of the first. Stimuli were detectability-matched auditory, visual, or auditory-visual signals and the goal was to compare changes in performance with eccentricity across modalities. Visual performance was superior to auditory at the midline, but inferior in the periphery, while auditory-visual performance exceeded both at all locations. No such advantage was seen when performance for auditory-only trials was contrasted with trials in which the first stimulus was auditory-visual and the second auditory only.

neuroscience↗

bioRxiv2017

Neural correlates of perceptual constancy in Auditory Cortex

Perceptual constancy requires neural representations that are selective for object identity, but also tolerant for identity-preserving transformations. How such representations arise in the brain and contribute to perception remains unclear. Here we studied tolerant representations of sound identity in the auditory system by recording multi-unit activity in tonotopic auditory cortex of ferrets discriminating the identity of vowels which co-varied across orthogonal stimulus dimensions (fundamental frequency, sound level, location and voicing). We found that neural decoding of vowel identity was most successful across the same orthogonal dimensions over which animals generalized their behavior. We also decoded orthogonal sound features and behavioral variables including choice and accuracy to show a behaviorally-relevant, multivariate and multiplexed representation of sound, with each variable represented over a distinct time-course. Finally, information content and timing of sound feature encoding was modulated by task-engagement and training, suggesting that tolerant representations during perceptual constancy are attentionally and experience-dependent.

neuroscience↗