Visual Cortex

Why do our eyes tend to be drawn to certain shapes, colors and silhouettes more than others? For more than half a century, researchers have know that neurons in the brain’s visual system respond more to some images than others a feature that is critical for the ability to recognize, understand and interpret the multitude of visual clues surrounding us.
For example, specific populations of visual neurons in an area of the brain known as the inferior temporal cortex fire more when people or other primates animals with highly attune and visual systems look at faces, places, objects or text. Now a small study in macaques led by investigators in the Blavatnik Institute at Harvard Medical School has generate some valuable clues base on an artificial intelligence system that can reliably determine what neurons in the brain’s visual cortex prefer to see.

Attempt to measure neuronal preferences

The vast majority of experiments to date that attempt to measure neuronal preferences have use real images. But real images carry an inherent bias: They are limit to stimuli available in the real world and to the images that researchers choose to test. The AI-base program overcomes this hurdle by creating synthetic images tailor to the preference of each neuron.

Will Xiao, a graduate student in the Department of Neurobiology at Harvard Medical School; so design a computer program that uses a form of responsive artificial intelligence; hence to create self-adjusting images base on neural responses obtained from six macaque monkeys. To do so, the researchers measure the firing rates from individual visual neurons in the brains of the animals; so as they were watching images on a computer screen.

Some of these images were in line with what she and her colleagues expect. For example, a neuron that they suspect might respond to faces evolve round pink images with two big black dots akin to eyes. Others were more surprising. For example, a neuron in one of the animals consistently generate images that look like the body of a monkey; but with a red splotch near its neck. The researchers eventually realize that this monkey was house near another that always wore a red collar.

Neuron responded preferentially

They think this neuron respond preferentially not just to monkey bodies but to a specific monkey; said study senior investigator Margaret Livingstone, the Takeda Professor of Neurobiology at HMS. Not every final image look like something recognizable, Xiao added. One monkey’s neuron evolve a small black square. Another evolve an amorphous black shape with orange below.
Livingstone notes that research from her lab and others has show; so that the responses of these neurons are not innate instead; hence they are learned through consistent exposure over time to visual stimuli. When this ability to recognize and fire preferentially to certain images arises is unknown, Livingstone said. She and her colleagues plan to investigate this question in future studies.

Learning how the visual system responds to images be key to better understanding; so the basic mechanisms that drive cognitive issues ranging from learning disabilities to autism spectrum disorders; which are often marked by impairments in a child’s ability to process facial cues and to recognize faces.

This malfunction in the visual processing apparatus of the brain can interfere with a child’s ability to connect; so communicate and interpret basic cues,” they said. By studying those cells that respond preferentially to faces, for example, we could uncover clues to how social development takes place and what might sometimes go awry.