SENSATION & PERCEPTION

Sensation

Process of detecting the presence of a stimulus.

Perception

Process of interpreting the stimulus.

Transduction

The process through which sensation is converted into sensory neural impulses.

Thalamus

The gateway to the cortex; all senses except olfaction go through the thalamus.

Fovea

Center of the retina where a sharp, clear image of an object is formed.

Rods

Receptor cells responsible for low-resolution vision, such as peripheral vision or vision at night.

Cones

Receptor cells responsible for acute and sharp vision, primarily located in the fovea and active in bright light.

Photoreceptors

Cells in the retina (rods and cones) that convert light into neural signals.

Visual field

The entire area that can be seen when the eyes are fixed in one position.

Primary visual cortex (V1)

Region in the occipital lobe that extracts basic information from the visual scene.

Extrastriate cortex

Receives input from V1 and processes higher-level visual information.

Hemianopia

Loss of vision restricted to one visual field due to a lesion in V1.

Scotoma

Blindness to discrete areas of the visual field caused by small lesions in V1.

Achromatopsia

Loss of color perception due to damage to V4; patients can distinguish shades of gray but not color.

Akinetopsia

Inability to perceive motion in a continuous manner due to lesions in V5.

Ventral pathway

The 'what' pathway from occipital to temporal lobe, involved in object recognition.

Dorsal pathway

The 'where' pathway from occipital to parietal lobe, involved in recognizing the location of objects.

Agnosia

Inability to recognize visually presented objects, can recognize through other modalities.

Apperceptive agnosia

A ventral-stream disorder where the ability to achieve object constancy is disrupted.

Associative agnosia

Failure of visual object recognition not linked to perceptual abilities, often due to semantic categorization issues.