Brain-reading
Encyclopedia
Brain-reading uses the responses of multiple voxel
s in the brain
evoked by stimulus
and then detected by fMRI in order to decode the original stimulus. Brain reading studies differ in the type of decoding (i.e. classification, identification and reconstruction) employed, the target (i.e. decoding visual patterns, auditory patterns, cognitive states), and the decoding algorithms (linear classification, nonlinear classification, direct reconstruction, Bayesian reconstruction, etc.) employed.
areas (V1, V2, and V3) to reconstruct geometric stimuli made up of flickering checkerboard patterns.
s forward of them (visual areas V3A, V3B, V4, and the lateral occipital) together with Bayesian inference
techniques to reconstruct complex natural images. This brain reading approach uses three components: A structural encoding model that characterizes responses in early visual areas; a semantic encoding model that characterizes responses in anterior visual areas; and a Bayseian prior that describes the distribution of structural and semantic scene statistics
.
Experimentally the procedure is for subjects to view 1750 black and white natural images that are correlated with voxel activation in their brains. Then subjects viewed another 120 novel target images, and information from the earlier scans is used reconstruct them. Natural images used include pictures of a seaside cafe and harbor, performers on a stage, and dense foliage.
brainwaves has been claimed to allow the recognition of phoneme
s, and at a 60% to 75% level color and visual shape words.
It has also been shown that brain-reading can be achieved in a complex virtual environment.
are impossible to achieve by any reconstruction algorithm on the basis of brain activity signals acquired by fMRI. This is
because all reconstructions will inevitably be limited by inaccuracies in the encoding models and noise in the measured signals.
Our resultswho? demonstrate that the natural image prior is a powerful (if unconventional) tool for mitigating the effects of these fundamental limitations. A natural image prior with only six million images is sufficient to produce reconstructions that are structurally and semantically similar to a target image."
Voxel
A voxel is a volume element, representing a value on a regular grid in three dimensional space. This is analogous to a pixel, which represents 2D image data in a bitmap...
s in the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
evoked by stimulus
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....
and then detected by fMRI in order to decode the original stimulus. Brain reading studies differ in the type of decoding (i.e. classification, identification and reconstruction) employed, the target (i.e. decoding visual patterns, auditory patterns, cognitive states), and the decoding algorithms (linear classification, nonlinear classification, direct reconstruction, Bayesian reconstruction, etc.) employed.
Classification
In classification, a pattern of activity across multiple voxels is used to determine the particular class from which the stimulus was drawn. Many studies have classified visual stimuli, but this approach has also been used to classify cognitive states.Reconstruction
In reconstruction brain reading the aim is to create a literal picture of the image that was presented. Early studies used voxels from early visual cortexVisual cortex
The visual cortex of the brain is the part of the cerebral cortex responsible for processing visual information. It is located in the occipital lobe, in the back of the brain....
areas (V1, V2, and V3) to reconstruct geometric stimuli made up of flickering checkerboard patterns.
Natural images
More recent studies used voxels from early and anterior visual cortex areaExtrastriate cortex
The extrastriate cortex is the region of the occipital cortex of the mammalian brain located next to the primary visual cortex, which is also named striate cortex because of its appeareance in the microscope. The extrastriate cortex encompasses multiple functional areas, including V3, V4, V5/MT...
s forward of them (visual areas V3A, V3B, V4, and the lateral occipital) together with Bayesian inference
Bayesian inference
In statistics, Bayesian inference is a method of statistical inference. It is often used in science and engineering to determine model parameters, make predictions about unknown variables, and to perform model selection...
techniques to reconstruct complex natural images. This brain reading approach uses three components: A structural encoding model that characterizes responses in early visual areas; a semantic encoding model that characterizes responses in anterior visual areas; and a Bayseian prior that describes the distribution of structural and semantic scene statistics
Scene statistics
Scene statistics is a discipline within the field of perception. It is concerned with the statistical regularities related to scenes. It is based on the premise that a perceptual system is designed to interpret scenes....
.
Experimentally the procedure is for subjects to view 1750 black and white natural images that are correlated with voxel activation in their brains. Then subjects viewed another 120 novel target images, and information from the earlier scans is used reconstruct them. Natural images used include pictures of a seaside cafe and harbor, performers on a stage, and dense foliage.
Other types
It is possible to track which of two forms of rivalrous binocular illusions a person was subjectively experiencing from fMRI signals. The category of event which a person freely recalls can be identified from fMRI before they say what they remembered. Statistical analysis of EEGEEG
EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...
brainwaves has been claimed to allow the recognition of phoneme
Phoneme
In a language or dialect, a phoneme is the smallest segmental unit of sound employed to form meaningful contrasts between utterances....
s, and at a 60% to 75% level color and visual shape words.
It has also been shown that brain-reading can be achieved in a complex virtual environment.
Accuracy
Brain-reading accuracy is increasing steadily as the quality of the data and the complexity of the decoding algorithms improve. In one recent experiment it was possible to identify which single image was being seen from a set of 120. In another it was possible to correctly identify 90% of the time which of two categories the stimulus came and the specific semantic category (out of 23) of the target image 40% of the time.Limitations
It has been noted that so far that brain reading is limited. "in practice exact reconstructionsare impossible to achieve by any reconstruction algorithm on the basis of brain activity signals acquired by fMRI. This is
because all reconstructions will inevitably be limited by inaccuracies in the encoding models and noise in the measured signals.
Our resultswho? demonstrate that the natural image prior is a powerful (if unconventional) tool for mitigating the effects of these fundamental limitations. A natural image prior with only six million images is sufficient to produce reconstructions that are structurally and semantically similar to a target image."
See also
- Bayesian brainBayesian brainBayesian brain is a term that is used to refer to the ability of the nervous system to operate in situations of uncertainty in a fashion that is close to the optimal prescribed by Bayesian statistics. This term is used in behavioural sciences and neuroscience and studies associated with this term...
- Brain fingerprintingBrain fingerprintingP300 - Brain Fingerprinting is a discarded and highly controversial forensic science technique that uses electroencephalography to determine whether specific information is stored in a subject’s brain...
- CyberwareCyberwareFor other uses; see Cyberware Cyberware is a relatively new and unknown field...
- Mind uploading
- NeuroinformaticsNeuroinformaticsNeuroinformatics is a research field concerned with the organization of neuroscience data by the application of computational models and analytical tools. These areas of research are important for the integration and analysis of increasingly large-volume, high-dimensional, and fine-grain...
- Minority Report (film)Minority Report (film)Minority Report is a 2002 American neo-noir science fiction film directed by Steven Spielberg and loosely based on the short story "The Minority Report" by Philip K. Dick. It is set primarily in Washington, D.C...
External links
- Brain scanners can tell what you're thinking about New ScientistNew ScientistNew Scientist is a weekly non-peer-reviewed English-language international science magazine, which since 1996 has also run a website, covering recent developments in science and technology for a general audience. Founded in 1956, it is published by Reed Business Information Ltd, a subsidiary of...
article on brain-reading 28 October 2009
- 2007 Pittsburgh Brain Activity Interpretation Competition:Interpreting subject-driven actions and sensory experience in a rigorously characterized virtual world