Accuracy of computer-guided surgery: A comparison of operator experience.

Statement Of Problem: Even though high-precision technologies have been used in computer-guided implant surgery, studies have shown that linear and angular deviations between the planned and placed implants can be expected.

Purpose: The purpose of this study was to evaluate the effect of operator experience on the accuracy of implant placement with a computer-guided surgery protocol.

Material And Methods: Ten surgically experienced and 10 surgically inexperienced operators participated in this study.

A clinically relevant accuracy study of computer-planned implant placement in the edentulous maxilla using mucosa-supported surgical templates.

Purpose: The purpose of the study is to determine the clinically relevant accuracy of implant placement in the edentulous maxilla using computer planning and a mucosa-supported surgical template.

Materials And Methods: In each of in total 30 consecutive edentulous patients suffering from retention problems of their upper denture, two or four Brånemark MkIII Groovy (Nobel Biocare®, Zürich, Switzerland) implants in the maxilla were installed. Preoperatively, first, a cone-beam computer tomography (cone beam computer tomography) scan was acquired, followed by virtual implant planning.

A clinically relevant validation method for implant placement after virtual planning.

Purpose: To design a relevant method to compare the virtual planned implant position to the ultimately achieved implant position and to evaluate, in case of discrepancy, the cause for this.

Materials And Methods: Five consecutive edentulous patients with retention problems of the upper denture received four implants in the maxilla. Preoperatively, first a cone-beam CT (CBCT) scan was acquired, followed by virtual implant planning.

Own song selectivity in the songbird auditory pathway: suppression by norepinephrine.

Background: Like human speech, birdsong is a learned behavior that supports species and individual recognition. Norepinephrine is a catecholamine suspected to play a role in song learning. The goal of this study was to investigate the role of norepinephrine in bird's own song selectivity, a property thought to be important for auditory feedback processes required for song learning and maintenance.

Implementation of spin-echo blood oxygen level-dependent (BOLD) functional MRI in birds.

The advent of high-field MRI systems has allowed the implementation of blood oxygen level-dependent functional MRI (BOLD fMRI) on small animals. An increased magnetic field improves the signal-to-noise ratio and thus allows an improvement in the spatial resolution. However, it also increases susceptibility artefacts in the commonly acquired gradient-echo images.

MRI in small brains displaying extensive plasticity.

Manganese-enhanced magnetic resonance imaging (ME-MRI), blood oxygen-level-dependent functional MRI (BOLD fMRI) and diffusion tensor imaging (DTI) can now be applied to animal species as small as mice or songbirds. These techniques confirmed previous findings but are also beginning to reveal new phenomena that were difficult or impossible to study previously. These imaging techniques will lead to major technical and conceptual advances in systems neurosciences.

Own-song recognition in the songbird auditory pathway: selectivity and lateralization.

The songbird brain is able to discriminate between the bird's own song and other conspecific songs. Determining where in the brain own- song selectivity emerges is of great importance because experience-dependent mechanisms are necessarily involved and because brain regions sensitive to self-generated vocalizations could mediate auditory feedback that is necessary for song learning and maintenance. Using functional MRI, here we show that this selectivity is present at the midbrain level.

Functional MRI of auditory responses in the zebra finch forebrain reveals a hierarchical organisation based on signal strength but not selectivity.

Background: Male songbirds learn their songs from an adult tutor when they are young. A network of brain nuclei known as the 'song system' is the likely neural substrate for sensorimotor learning and production of song, but the neural networks involved in processing the auditory feedback signals necessary for song learning and maintenance remain unknown. Determining which regions show preferential responsiveness to the bird's own song (BOS) is of great importance because neurons sensitive to self-generated vocalisations could mediate this auditory feedback process.

Neural representation of spectral and temporal features of song in the auditory forebrain of zebra finches as revealed by functional MRI.

Song perception in songbirds, just as music and speech perception in humans, requires processing the spectral and temporal structure found in the succession of song-syllables. Using functional magnetic resonance imaging and synthetic songs that preserved exclusively either the temporal or the spectral structure of natural song, we investigated how vocalizations are processed in the avian forebrain. We found bilateral and equal activation of the primary auditory region, field L.

Functional magnetic resonance imaging in zebra finch discerns the neural substrate involved in segregation of conspecific song from background noise.

Recently, fMRI was introduced in a well-documented animal model for vocal learning, the songbird. Using fMRI and conspecific signals mixed with different levels of broadband noise, we now demonstrate auditory-induced activation representing discriminatory properties of auditory forebrain regions in anesthetized male zebra finches (Taeniopygia guttata). Earlier behavioral tests showed comparable calling responses to the original conspecific song stimulus heard outside and inside the magnet.

IR-SE and IR-MEMRI allow in vivo visualization of oscine neuroarchitecture including the main forebrain regions of the song control system.

Songbirds share with humans the capacity to produce learned vocalizations (song). Recently, two major regions within the songbird's neural substrate for song learning and production; nucleus robustus arcopallii (RA) and area X (X) are visualized in vivo using Manganese Enhanced MRI (MEMRI). The aim of this study is to extend this to all main interconnected forebrain Song Control Nuclei.

Spatiotemporal properties of the BOLD response in the songbirds' auditory circuit during a variety of listening tasks.

Auditory fMRI in humans has recently received increasing attention from cognitive neuroscientists as a tool to understand mental processing of learned acoustic sequences and analyzing speech recognition and development of musical skills. The present study introduces this tool in a well-documented animal model for vocal learning, the songbird, and provides fundamental insight in the main technical issues associated with auditory fMRI in these songbirds. Stimulation protocols with various listening tasks lead to appropriate activation of successive relays in the songbirds' auditory pathway.