[PDF] Invariant visual representation by single neurons in the human brain | Semantic Scholar (2024)

This thesis discusses the issue of how best to quantify sparseness, particularly in very sparse systems where biases are significant, and shows results obtained by applying an existing model of sparse coding both to unsupervised category discovery in images and to differentiation between images of different individuals.

During realistic viewing experiences, typical neurons in the human medial temporal lobe code for a considerable range of objects, across multiple semantic categories.

By recording from 415 neurons in the hippocampus and amygdala of human epilepsy patients as they viewed images drawn from 10 image categories, it is shown that the firing rates of 8% of these neurons encode image illuminance and contrast, low-level properties not directly pertinent to task performance, whereas in 7% of the neurons, firing rates encode the category of the item depicted in the image, a high-level property pertinent to the task.

The properties of neurons in a small region of the monkey anterior temporal cortex that respond to the sight of familiar faces are reported, establishing a new pathway for the fast recognition of familiar individuals.

It is found that neurons located along the progression of extrastriate areas that, in the rat brain, run laterally to primary visual cortex, encode object information, with a progressive functional specialization of neural responses along these areas.

These single-cell recordings within the human face processing system provide vital experimental evidence linking previous imaging studies in humans and invasive studies in animal models.

The macaque inferotemporal cortex contains face-selective cells that show virtually no change in their patterns of visual responses over time periods as long as one year, and it is proposed that neurons in the AF face patch are specialized for aspects of face perception that demand stability as opposed to plasticity.

...

...

Recording from 427 single neurons in the human hippocampus, entorhinal cortex and amygdala found a remarkable degree of category-specific firing of individual neurons on a trial-by-trial basis, providing direct support for the role of human medial temporal regions in the representation of different categories of visual stimuli.

Findings indicate that explanations in terms of arousal, emotional or motor reactions, simple visual feature sensitivity or receptive fields are insufficient to account for the selective responses to faces and face features observed in this population of STS neurones.

It is shown that neurons in the hippocampus of the monkey appear to categorize types of visual stimuli presented in a delayed-match-to-sample memory task, and these category cells are able to encode aspects of behaviorally important images instead of encoding all visual details.

A group of shape-selective neurons in an anterior ventral part of the temporal cortex of monkeys that exhibited sustained activity during the delay period of a visual short-term memory task are reported.

Population analysis of cells in the temporal cortex of monkeys showed that information is carried at the level of the population and that representations of complex stimuli in the higher visual areas may take the form of a sparse population code.

Evidence from the fields of psychology, neuropsychology, and neurophysiology supports the idea that there are multiple systems for recognition of objects, and indicates that one system may represent objects by combinations of multiple views, or aspects, and another may represent Objects by structural primitives and their spatial interrelationships.

The perception of 3D novel objects was found to be a function of the object's retinal projection at the time of the recognition encounter, and a number of neurons with remarkable selectivity for individual views of those objects that the monkey had learned to recognize were found.

...

...