Psych Sensory Pathways

Vision

Stimulus: Light enters the eye through the cornea, pupil, and focused by the lens onto the retina.

Photoreceptors: Rods and cones in the retina detect light and color.

Optic Nerve: Sends information to the optic chiasm, where some fibers cross to the opposite side.

Thalamus (LGN): Relays and processes the information. New neurons carry information to the...

Primary Visual Cortex (Occipital Lobe, V1): Processes basic visual input like edges, color, and motion. The visual input is also sent to other cortical areas so multiple aspects can be processed at the same time.

Audition (hearing)

Stimulus: Sound waves enter the ear and vibrate the tympanic membrane (eardrum).

Middle Ear Bones: The malleus, incus, and stapes amplify vibrations.

Cochlea: Vibrations create waves in the basilar membrane, stimulating hair cells.

Hair Cells: Convert mechanical energy into neural signals.

Auditory Nerve (Cochlear Nerve): Carries signals to the brainstem (cochlear nuclei in the medulla).

Brainstem: Processes spatial location of sound.

Thalamus: Relays signals to the cortex.

Primary Auditory Cortex (Temporal Lobe): Processes pitch, volume, and sound location.

Olfaction (Smell)

Stimulus: Airborne odor molecules bind to olfactory receptor neurons in the nasal cavity.

Olfactory Receptor Cells: Convert chemical signals into electrical impulses.

Olfactory Bulb: Processes and organizes smell information.

Primary Olfactory Cortex Processes odor information. For my more neuroscience minded students- Amygdala, hippocampus & Limbic System: Links smells to emotions and memories

Gustation (Taste)

Stimulus: Tastants (chemical molecules) dissolve in saliva and arrive at taste buds, which are arranged around Papillae on tongue

Taste Receptor Cells: Convert chemical signals into neural impulses.

Cranial Nerves Transmit taste signals to the brainstem.

Brainstem

Thalamus Relays information to the cortex.

Primary Gustatory Cortex Interprets taste perception.

Touch (Somatosensation)

Stimulus: Mechanical, thermal, or pain-related stimuli activate skin receptors.

Peripheral Nerves: Carry signals to the spinal cord via dorsal root ganglia.

Spinal Cord: Relays signals via ascending pathways (dorsal column-medial lemniscus for fine touch; spinothalamic tract for pain & temperature).

Brainstem: Further processing and relaying.

Thalamus Filters and directs sensory signals.

Somatosensory Cortex Processes touch, pressure, temperature, and pain.

Vestibular Sense

Stimulus: Head movement or changes in gravity detected by the semicircular canals & otolith organs in the inner ear.

Hair Cells Convert mechanical movement into neural signals.

Vestibular Nerve Sends signals to the medulla and pons in the brainstem).

Cerebellum: Helps coordinate balance and posture.

Thalamus (Ventral Posterior Nucleus, VPN): Filters and relays vestibular information.

Cortex Processes body position and movement.

Proprioception (Kinesthetic sense)

Stimulus: Muscle stretch, joint angle, and tendon tension detected by muscle spindles and other sensing structures in muscles and joints

Peripheral Nerves: Transmit signals to the spinal cord.

Spinal Cord: Sends information upward.

Brainstem Processes proprioceptive signals.

Cerebellum: Fine-tunes movement and balance.

Thalamus Relays information to the cortex.

Primary Somatosensory Cortex (Parietal Lobe) and Motor Cortex: Processes body position awareness, adjusts movement accordingly.