Lecture 5 - Sensation and Perception Lecture Notes

Flashcards covering the definitions and key concepts of sensation, perception, and the specific sensory systems (olfaction, gustation, somatosensation, audition, and vision) based on the lecture transcript.

Sensation

The way our sensory organs receive information from the environment and input it into neuronal activity.

Senses

Physiological capacities to provide input from the environment to our brain, critical for survival (e.g., avoiding threats and approaching rewards).

Olfactory epithelium

The roof of the nasal cavity where odor receptors are embedded.

Odorants

Molecules that give off a smell and are picked up in the nose.

Glomeruli

A cluster of convergent olfactory sensory neurons that produce a different pattern of activity for different odorants.

Primary olfactory cortex

The processing area for smell; notably, olfactory information is the only sense that does not pass through the thalamus before reaching its cortex.

Pheromones

Chemical signals conveyed by olfaction that provide social information and influence autonomic behavior, attention, memory, and emotion.

Chorda tympani nerve

The nerve formed by inputs from taste receptor cells that eventually connects through the facial and glossopharyngeal nerves.

Nucleus of the solitary tract

A location in the brainstem containing the gustatory nucleus where taste signals project.

Ventral posterior medial nucleus

The specific part of the thalamus that receives taste signals from the brainstem.

Orbitofrontal cortex

The area where smell and taste information are integrated.

5 basic tastes

Salty, sour, sweet, bitter, and umami.

Merkel’s cells

Somatosensory receptors that detect regular touch.

Meissner’s corpuscules

Somatosensory receptors that detect light touch.

Pacinian corpuscules

Somatosensory receptors that detect deep pressure.

Ruffini corpuscles

Somatosensory receptors that detect temperature.

Nociceptors

Receptors that signal pain; includes thermal (hot/cold), multimodal (wide range of noxious stimuli), and mechanical (heaviness) types.

Reflex arcs

Synapses where some receptors connect directly with motor neurons to produce quick movements.

Sensory homunculus

A somatotopic representation of the body where the cortical area is directly proportional to the importance of somatosensory information from that part (e.g., hands for humans, whiskers for mice).

Primary somatosensory cortex

The initial area for processing mechanical stimuli affecting the body, demonstrated by Elbert et al. (1995) to be highly plastic.

Cochlea

An inner ear structure containing tiny hair cells that act as receptors responding to frequencies under $20\,kHz$.

Olivary nucleus

A structure in the pons where the integration of information from both ears occurs.

Inferior colliculus

A midbrain structure that allows auditory information to access the motor system for functions like orienting the head toward sound.

Tonotopic map

The systematic representation of frequency where hair cells are arranged according to the sound frequencies that most effectively stimulate them.

Rods

Photoreceptors ($260$ million) used for low light that do not process color.

Cones

Photoreceptors used for higher light levels and color vision.

Ganglion cells

Cells that process and compress information from photoreceptors before sending it through the optic nerve to the CNS.

Retinogeniculate pathway

The common visual pathway projecting information from the retina to the LGN to the thalamus.

Retinotopic maps

Representations that map the field of vision onto the brain, keeping track of the location of objects in specific regions of space.

Jiang et al. (2007)

Study showing that sensation becomes perceivable at later processing stages, as early visual areas (V1, V4) can distinguish color at $30\,Hz$ flickering while later areas cannot.

Superior Temporal Sulcus

A site where connections to and from different sensory cortices exist, facilitating multimodal perception.

Synesthesia

An idiosyncratic phenomenon where senses are mixed up, such as tasting words.

Cortical plasticity

The functional reorganization of the brain in response to injury, disability, or congenital conditions, where unused sensory areas are repurposed to process other senses.

Merabet et al. (2008)

A study where blindfolded participants showed use of the visual cortex for somatosensory tasks (reading braille) after one week, demonstrating rapid plasticity.