Sensory Receptors and Neural Pathways (6A) - Psych & Soc

Which cortical lobe contains primary auditory cortex (A1)?

Temporal lobe. Superior temporal gyrus processes sound and auditory information.
Which thalamic nucleus relays most visual information to primary visual cortex (V1)?

Lateral geniculate nucleus (LGN). Six-layered structure organizing visual info from optic tract.
Which law states that the JND is a constant fraction of the initial stimulus intensity?

Webers law. States that $\Delta I/I = k$ (constant ratio of change to initial intensity).
Which theory explains pitch coding by frequency of auditory nerve firing for lower frequencies?

Frequency theory. Nerve firing rate matches sound wave frequency up to ~1000 Hz.
Which somatosensory pathway carries pain and temperature to cortex?

Spinothalamic (anterolateral) pathway. Crosses at spinal level; relays through VPL thalamus.
What is the term for the minimum stimulus intensity that is detected $50\%$ of the time?

Absolute threshold. The weakest stimulus detected half the time.
What is the name of the sensory receptor type that detects mechanical pressure or vibration?

Mechanoreceptor. Responds to physical deformation from touch, pressure, or stretch.
What is a sensory receptor in terms of transduction and the type of stimulus it detects?

A specialized cell that transduces a specific stimulus into neural signals. Receptors are specialized for one stimulus type and convert it to action potentials.
Which thalamic nucleus relays auditory information to primary auditory cortex?

Medial geniculate nucleus (MGN). Processes tonotopic information from inferior colliculus.
Which retinal cells carry output from the retina to the optic nerve?

Ganglion cells. Their axons form the optic nerve.
What is the difference between tonic and phasic sensory receptors?

Tonic: sustained firing; phasic: rapid adaptation to constant stimuli. Tonic receptors signal continuously; phasic receptors signal changes only.
What type of receptor primarily transduces pressure, vibration, and stretch?

Mechanoreceptors. These detect mechanical deformation of tissue.
What is the primary role of the medial geniculate nucleus (MGN)?

Thalamic relay from auditory pathways to auditory cortex. Processes auditory signals before cortical projection.
Which spinal pathway primarily carries pain and temperature information to the brain?

Spinothalamic tract (anterolateral system). Crosses at spinal level and ascends contralaterally.
What thalamic nucleus is the primary relay for somatosensory input from the face?

Ventral posteromedial nucleus (VPM). Relays touch/proprioception from face via trigeminal nerve.
What thalamic nucleus is the primary relay for somatosensory input from the body (not face)?

Ventral posterolateral nucleus (VPL). Relays touch/proprioception from body below neck to cortex.
Which receptor type primarily detects temperature changes at the skin surface?

Thermoreceptors. Contain ion channels that open/close in response to temperature changes.
What is the primary cortical area that receives auditory input relayed by the MGN?

Primary auditory cortex in the superior temporal gyrus. Heschl's gyrus processes frequency and temporal sound patterns.
Which thalamic nucleus relays somatosensory information to the primary somatosensory cortex?

Ventral posterior nucleus (VPL/VPM). VPL processes body; VPM processes face sensations.
Which thalamic nucleus relays visual information to the primary visual cortex?

Lateral geniculate nucleus (LGN). Part of thalamus that processes visual information.
What does Weber's law state about the just noticeable difference (JND)?

JND is a constant fraction of baseline intensity: $\frac{\Delta I}{I}=k$ . The ratio of change to baseline remains constant across intensities.
Which thalamic nucleus relays visual information to primary visual cortex?

Lateral geniculate nucleus (LGN). LGN processes visual signals before sending to occipital lobe.
Which pathway carries fine touch, vibration, and proprioception to the thalamus?

Dorsal column–medial lemniscus pathway. Crosses at medulla; precise touch and position sense.
What is the general pathway name for sensory signals traveling to the CNS?

Afferent pathway. Carries sensory information toward the brain.
Which retinal photoreceptor supports color vision and high visual acuity?

Cones. These photoreceptors have pigments for red, green, or blue light, enabling color perception and detail in bright conditions.
Which thalamic nucleus relays somatosensory information to primary somatosensory cortex?

Ventral posterior nucleus (VPL/VPM). VPL receives body info; VPM receives face/head info.
Which somatosensory receptors detect light touch and flutter in glabrous skin?

Meissner corpuscles. Rapidly adapting mechanoreceptors in hairless skin areas like fingertips.
Which sensory modality reaches cortex without first synapsing in the thalamus?

Olfaction (smell). Smell signals go directly to olfactory cortex, bypassing thalamus.
Which receptor type detects temperature changes (hot or cold)?

Thermoreceptors. Free nerve endings that respond to temperature; separate cold and warm receptors.
What is the main somatosensory pathway for pain and temperature?

Spinothalamic (anterolateral) pathway. Crosses spinal cord to carry nociceptive and thermal signals.
What does Weber's law state about the just-noticeable difference relative to stimulus intensity?

JND is a constant proportion of baseline intensity. Weber found that JND = k × I, where k is constant and I is baseline intensity.
Which thalamic nucleus relays visual information from the retina to primary visual cortex?

Lateral geniculate nucleus (LGN). Part of the visual pathway from eye to occipital lobe.
Identify the receptor type that detects mechanical deformation (pressure, vibration, stretch).

Mechanoreceptors. Respond to physical forces like touch, hearing, and proprioception.
Which sensory modality bypasses the thalamus on its initial route to cortex?

Olfaction (smell). Olfactory signals project directly to cortex without thalamic relay.
Which cortical lobe contains the primary somatosensory cortex (postcentral gyrus)?

Parietal lobe. Postcentral gyrus processes touch, pressure, temperature, and proprioception.
Which pathway carries pain and temperature information from body to thalamus?

Spinothalamic tract (anterolateral system). Crosses at spinal level; slow, poorly localized pain.
Which inner ear structure contains hair cells that transduce sound vibrations?

Organ of Corti (in the cochlea). Hair cells here bend with fluid waves from sound, converting vibrations into neural impulses.
What is the retinal region where the optic nerve exits and no photoreceptors are present?

Optic disc (blind spot). Where ganglion cell axons exit retina, creating a blind spot.
What is the difference between an afferent neuron and an efferent neuron?

Afferent: to CNS; efferent: from CNS to effectors. Afferent carries sensory info inward; efferent carries motor commands outward.
Which visual photoreceptor mediates high acuity and color vision in bright light?

Cones. Concentrated in fovea for detailed central vision.
Which retinal photoreceptor is specialized for color vision and high acuity?

Cones. Three types (S, M, L) contain photopsins for red, green, and blue wavelengths.
Identify the receptor type that detects temperature changes in the skin and body.

Thermoreceptors. Separate receptors for cold and warm sensations.
What is tonotopic organization in the cochlea?

Base codes high frequency; apex codes low frequency. Frequency mapping along cochlear length enables pitch discrimination.
Identify the correct mapping: which sensory modality primarily uses chemoreceptors?

Olfaction and gustation. Smell and taste rely on chemical binding to receptors, unlike mechanical or light-based senses.
What is the difference between an afferent neuron and an efferent neuron?

Afferent: to CNS; efferent: from CNS to muscles/glands. Afferent carries sensory info inward; efferent carries motor commands outward.
Which receptor type primarily detects tissue damage or noxious stimuli?

Nociceptors. Pain receptors respond to potentially harmful stimuli.
Identify the receptor type that detects tissue damage and is associated with pain perception.

Nociceptors. Free nerve endings that signal potential or actual tissue harm.
Which sensory receptor type responds primarily to light (photons) in the retina?

Photoreceptors. Light-sensitive cells containing photopigments.
What is the absolute threshold in psychophysics?

Minimum stimulus detected $50\%$ of the time. The weakest intensity that can be perceived half the time.
Which somatosensory receptors detect temperature and pain (noxious stimuli)?

Free nerve endings (thermoreceptors and nociceptors). Unmyelinated nerve endings that respond to extreme temperatures and tissue damage.
What is the difference between adequate stimulus and threshold stimulus for a receptor?

Adequate: preferred modality; threshold: minimum intensity to detect. Adequate is the optimal stimulus type; threshold is the weakest detectable intensity.
What is the function of nociceptors in somatosensation?

Detect potentially damaging stimuli and signal pain. They respond to tissue damage or extreme temperatures/pressures.
Identify the vestibular system function most directly tested on the MCAT.

Balance and spatial orientation (head position and motion). Inner ear organs detect head movements and maintain equilibrium.
Which retinal photoreceptors are most sensitive in dim light and support night vision?

Rods. Contain rhodopsin, highly sensitive to light but provide no color information.
What is lateral inhibition in sensory systems?

Neighboring neurons inhibit each other to sharpen contrast. Enhances edges and boundaries in sensory perception.
Which thalamic nucleus relays auditory information to the primary auditory cortex?

Medial geniculate nucleus (MGN). Part of thalamus that processes auditory information.
What is the correct neural pathway for vision from retina to cortex?

Retina optic nerve LGN (thalamus) V1 (occipital). Visual signals relay through lateral geniculate nucleus before reaching primary visual cortex.
What is the key functional difference between the fovea and the optic disc?

Fovea: highest acuity; Optic disc: blind spot (no photoreceptors). Fovea has only cones for sharp vision; optic disc lacks receptors entirely.
Which option best describes contralateral sensory processing in the somatosensory system?

Each hemisphere primarily represents sensation from the opposite side of the body. Due to decussation of ascending sensory pathways.
What is adequate stimulus, and what does it predict about receptor sensitivity?

Preferred stimulus type; receptor is most sensitive to that modality. Each receptor type responds best to its specific stimulus modality.
Which retinal cells send action potentials through the optic nerve to the brain?

Retinal ganglion cells. Only ganglion cells generate action potentials in the retina.
Identify the correct order of the visual pathway from retina to cortex.

Retina → optic nerve → optic chiasm → LGN → optic radiations → V1. Visual signals cross at chiasm before reaching thalamus and cortex.
What is a sensory receptor in terms of stimulus transduction into neural signals?

A cell/ending that transduces stimuli into action potentials. Converts physical/chemical stimuli into electrical signals for nervous system processing.
Which cranial nerve carries olfactory information from nasal epithelium to the brain?

Olfactory nerve (CN I). Only cranial nerve that bypasses thalamus, going directly to cortex.
What is the key distinction between rods and cones in the retina regarding function?

Rods: dim light; cones: color and acuity. Rods for scotopic vision; cones for photopic and color vision.
Which receptor type primarily detects mechanical deformation (touch, vibration, stretch)?

Mechanoreceptors. These respond to pressure, vibration, and stretch in skin and organs.
What is the correct order of the auditory pathway from cochlea to cortex?

Cochlea → brainstem → inferior colliculus → MGN → A1. Sound ascends through brainstem nuclei and thalamus to temporal cortex.
Identify the structure where nasal retinal fibers cross to the opposite hemisphere in vision.

Optic chiasm. X-shaped crossing where nasal fibers decussate for binocular vision.
What is the functional distinction between afferent and efferent neurons in neural pathways?

Afferent: sensory to CNS; efferent: motor from CNS to effectors. Afferent = arriving at CNS; efferent = exiting CNS (remember SAME: Sensory-Afferent).
Which visual field is processed by the left primary visual cortex (V1)?

Right visual field. Contralateral processing: left V1 receives right visual field.
What is the difference between tonic and phasic receptors?

Tonic: sustained firing; phasic: rapid adaptation, onset/offset firing. Tonic detect sustained stimuli; phasic detect changes.
Which thalamic nucleus relays auditory information to auditory cortex?

MGN (medial geniculate nucleus). Sound information relays through this thalamic nucleus.
Which receptor type detects stretch, vibration, pressure, and body position (proprioception)?

Mechanoreceptors. Respond to mechanical deformation of tissue.
What are the four primary types of sensory receptors by stimulus modality?

Mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors. Classified by the type of physical stimulus they detect.
Identify the visual photoreceptor that mediates high-acuity color vision in bright light.

Cones. Three cone types (S, M, L) enable trichromatic vision in photopic conditions.
What are the four main sensory receptor types by stimulus modality?

Mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors. These four types classify receptors by the stimulus they detect.
Which thalamic nucleus relays visual information from the optic tract to primary visual cortex?

Lateral geniculate nucleus (LGN). Six-layered structure organizing visual signals before cortical processing.
What is the fovea, and what is its major contribution to vision?

Cone-dense retinal region for highest visual acuity. High cone density enables sharp central vision for detailed tasks.
What is the retinal location where the optic nerve exits and no photoreceptors are present?

Optic disc (blind spot). Where ganglion cell axons converge to form the optic nerve; creates blind spot.
Which thalamic nucleus relays visual information from the optic tract to primary visual cortex?

Lateral geniculate nucleus (LGN). Thalamic relay station for visual processing.
What is the optic disc, and what key visual consequence does it produce?

Exit of optic nerve; creates the blind spot. Axons bundle here to form the optic nerve, leaving no photoreceptors and thus a gap in the visual field.
Which thalamic nucleus is the primary relay for auditory information to auditory cortex?

Medial geniculate nucleus (MGN). Thalamic relay station for hearing before reaching A1.
What is the correct neural pathway order for audition from cochlea to primary auditory cortex?

Cochlea → CN VIII → thalamus (MGN) → auditory cortex (temporal lobe). CN VIII carries signals from inner ear; MGN relays to superior temporal gyrus.
What is the primary visual pathway from retina to primary visual cortex?

Retina → optic nerve → LGN → optic radiation → V1. Visual signals relay through thalamus (LGN) before reaching occipital cortex.
What thalamic nucleus relays somatosensory information from the body to cortex?

VPL (ventral posterolateral) nucleus. Body sensations below neck relay through this thalamic nucleus.
Which thalamic nucleus relays visual information to primary visual cortex?

LGN (lateral geniculate nucleus). Visual information relays through this thalamic nucleus.
What is the difference between an afferent neuron and an efferent neuron?

Afferent: to CNS; efferent: from CNS to muscles or glands. Afferent carries sensory info in; efferent carries motor commands out.
What is a receptive field for a sensory neuron?

Region of sensory space that alters that neuron's firing. Stimulation here excites or inhibits the neuron's response.
Which sensory pathway primarily carries fine touch, vibration, and proprioception: dorsal column or spinothalamic?

Dorsal column–medial lemniscus pathway. Crosses at medulla; fast, precise tactile and position sense.
What is the name of the sensory receptor type that detects body position and movement?

Proprioceptor. Located in muscles and joints to sense body position in space.
What type of receptor primarily transduces chemicals for taste and smell?

Chemoreceptors. These detect chemical molecules in gustatory and olfactory systems.
Which receptor type detects tissue damage and signals pain?

Nociceptors. Specialized free nerve endings detecting harmful stimuli.
What is the adequate stimulus for a sensory receptor?

The stimulus type the receptor is most sensitive to. Each receptor type evolved to detect specific stimulus forms.
Which cranial nerve carries olfactory information to the brain?

Olfactory nerve (CN I). Only sensory nerve that bypasses thalamus, projecting directly to limbic structures.
Which sensory pathway primarily carries pain and temperature to the brain: dorsal column or spinothalamic?

Spinothalamic tract. Crosses at spinal level; slower, less precise than dorsal column.
Which cortical area is the primary visual cortex that receives LGN input?

Occipital lobe (V1, striate cortex). Located in occipital lobe; processes basic visual features like edges and orientation.
What is a nociceptor?

A pain receptor that detects actual or potential tissue damage. Specialized free nerve endings that signal harmful stimuli.
What are photoreceptors, and where are they located?

Rods and cones in the retina. Light-sensitive cells containing photopigments that initiate vision.
What type of sensory receptor detects mechanical deformation such as touch, pressure, or vibration?

Mechanoreceptor. Responds to physical forces like bending or stretching.
What is the main somatosensory pathway for fine touch and proprioception?

Dorsal column–medial lemniscus pathway. Carries discriminative touch via brainstem nuclei to thalamus.
What type of sensory receptor detects changes in temperature at the skin or in the body?

Thermoreceptor. Includes cold and warm receptors that respond to thermal changes.
Which retinal photoreceptor is most sensitive in dim light and supports black-and-white vision?

Rods. High sensitivity due to rhodopsin; no color discrimination.
What type of sensory receptor transduces light into neural signals in the retina?

Photoreceptor (rods and cones). Rods detect dim light; cones detect color and bright light.
Which receptor type primarily detects temperature changes?

Thermoreceptors. Separate receptors exist for detecting hot and cold stimuli.
What is the correct neural pathway for vision from retina to primary visual cortex?

Retina → optic nerve → LGN → V1 (occipital lobe). Visual signals travel from retinal ganglion cells through the thalamus to the cortex for initial processing.
Identify the receptor type that best detects light in the retina.

Photoreceptors (rods and cones). These specialized cells contain photopigments that respond to light.
Which receptor type detects light in the retina: rods or cones?

Both; rods for dim light, cones for color and high acuity. Both photoreceptor types detect light but serve different visual functions.
What is the term for reduced receptor responsiveness after prolonged stimulation?

Sensory adaptation. Decreased firing rate with constant stimulation allows detection of new changes.
Which pathway carries pain and temperature information to the thalamus and cortex?

Spinothalamic (anterolateral) pathway. Crosses at spinal level; small fibers for nociception and thermal sense.
Identify the structure where nasal retinal fibers cross to the opposite hemisphere.

Optic chiasm. X-shaped structure where medial retinal fibers decussate for binocular vision.
Which cranial nerve carries visual information from the retina to the brain?

Optic nerve (CN II). Composed of ganglion cell axons carrying visual signals to the brain.
Which spinal pathway primarily carries vibration, fine touch, and proprioception information?

Dorsal column–medial lemniscus pathway. Ascends ipsilaterally, crosses at medulla in medial lemniscus.
What is the name of the process by which sensory receptors convert stimuli into neural signals?

Sensory transduction. Converts physical stimuli into electrical signals neurons can process.
Which thalamic nucleus is the major relay for somatosensory information to the cortex?

Ventral posterolateral nucleus (VPL). Receives input from dorsal columns and spinothalamic tract.
Which sensory modality bypasses the thalamus on its initial path to cortex?

Olfaction (smell). Projects directly to limbic structures, explaining smell-emotion links.
Which thalamic nucleus relays visual information to the primary visual cortex?

Lateral geniculate nucleus (LGN). This thalamic structure organizes retinal inputs retinotopically before relaying to the visual cortex.
Which retinal photoreceptors mediate color vision and high visual acuity in bright light?

Cones. Contain photopigments for red, green, or blue light.
What is sensory adaptation?

Decreased receptor responsiveness during constant stimulation. Allows filtering of constant, non-changing stimuli.
What is the correct order of the auditory pathway from cochlea to primary auditory cortex?

Cochlea → CN VIII → MGN → primary auditory cortex. Sound travels via vestibulocochlear nerve to thalamus then cortex.
Which auditory pathway carries sound information to primary auditory cortex?

Cochlea CN VIII brainstem MGN A1. MGN is the thalamic relay for auditory information.
Which term names the minimal stimulus intensity that can be detected $50\%$ of the time?

Absolute threshold. The minimum detectable stimulus level, defined statistically.
What is the correct pathway for somatosensory touch information to reach cortex?

Spinal cord thalamus primary somatosensory cortex (parietal). Touch signals cross midline and synapse in ventral posterior lateral thalamus.
What is the optic chiasm?

Partial crossing of optic nerve fibers. Where nasal fibers cross to opposite hemisphere.
What are the five major sensory receptor types based on stimulus modality?

Mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors, nociceptors. Each type responds to specific stimuli: touch, chemicals, light, temperature, or pain.
What does the gate control theory of pain propose about pain signaling in the spinal cord?

Spinal gating modulates pain transmission to the brain. Non-painful input can close the gate and reduce pain perception.
Which receptor type detects mechanical deformation such as pressure, stretch, or vibration?

Mechanoreceptors. Respond to physical forces that distort cell membranes, opening ion channels.
What is the term for decreased receptor responsiveness after constant stimulation?

Sensory adaptation. Receptors become less sensitive to unchanging stimuli.
What retinal structure contains the highest density of cones and produces greatest visual acuity?

Fovea centralis. Central retinal pit packed with cones for sharp central vision.
What is the optic chiasm and what crosses there?

Junction where nasal retinal fibers decussate (cross to opposite side). Crossing allows each hemisphere to process contralateral visual field.
Which receptor type is most directly activated by light in the retina?

Photoreceptors (rods and cones). Rods and cones contain photopigments that absorb light and trigger phototransduction.
Which receptor type detects tissue damage and is associated with pain perception?

Nociceptors. Free nerve endings activated by harmful stimuli signaling potential tissue damage.
Which receptor type primarily detects potentially damaging stimuli and signals pain?

Nociceptors. High-threshold receptors activated by intense stimuli that threaten tissue damage.
What type of sensory receptor detects tissue damage and signals pain?

Nociceptors. These receptors detect harmful stimuli like extreme pressure or chemicals, initiating pain signals for protection.
What is the definition of sensory transduction in a sensory receptor cell?

Conversion of stimulus energy into neural signals. Receptors convert physical/chemical stimuli into electrical signals neurons can process.
What law states that the JND is a constant proportion of the original stimulus intensity?

Weber's law. JND equals a constant fraction of the stimulus magnitude.
Which thalamic nucleus is the primary relay for visual information to primary visual cortex?

Lateral geniculate nucleus (LGN). Thalamic relay station for vision before reaching V1.
What is lateral inhibition in sensory systems?

Neighboring neurons suppress each other to enhance contrast and edges. Creates sharper boundaries between stimulated regions.
Which thalamic nucleus is the main relay for somatosensory information to the somatosensory cortex?

Ventral posterior nucleus (VPL/VPM). VPL relays body sensation, VPM relays face sensation to somatosensory cortex.
What is the primary cortical region for vision (initial visual processing)?

Primary visual cortex (V1) in the occipital lobe. V1 processes basic features like edges and motion from LGN projections in a retinotopic map.
Which pathway carries fine touch, vibration, and proprioception to the thalamus and cortex?

Dorsal column–medial lemniscus pathway. Crosses at medulla; large fibers for discriminative touch.
What is the primary sensory cortex for audition (name and lobe)?

Primary auditory cortex in temporal lobe. First cortical area processing sound information.
Identify the receptor type that detects chemicals for smell and taste.

Chemoreceptors. Bind specific molecules to trigger sensory transduction.
What is the primary cortical area that receives visual input relayed by the LGN?

Primary visual cortex (V1) in the occipital lobe. Striate cortex processes basic features like edges and orientation.
Identify the receptor type that detects potentially damaging stimuli (pain).

Nociceptors. Pain receptors that signal tissue damage or potential harm.
What is the correct sequence of information flow in a basic sensory pathway from stimulus to response?

Stimulus → receptor → afferent neuron → CNS → efferent neuron → effector. Standard pathway from sensory input through processing to motor output.
What is the correct neural pathway for audition from cochlea to primary auditory cortex?

Cochlea → auditory nerve → MGN → A1 (temporal lobe). Auditory signals from hair cells pass via the brainstem and thalamus to the cortex for sound analysis.
What term describes a sensory receptor's baseline level of activity without stimulation?

Spontaneous firing (baseline activity). Receptors fire at low rates even without stimulation.
What type of sensory receptor detects tissue damage or painful stimuli?

Nociceptor. Free nerve endings that signal potential tissue harm.
Which sensory pathway is the major exception to the rule that sensory input relays through the thalamus?

Olfaction (smell). Bypasses thalamus, projects directly to cortex.
Which cranial nerve carries visual information from the retina to the brain?

Optic nerve (CN II). Second cranial nerve transmitting visual signals to brain.
Which inner ear structure transduces sound vibrations into neural signals?

Hair cells in the organ of Corti (cochlea). Mechanoreceptor hair cells convert basilar membrane vibrations to signals.
Which receptor type primarily detects light in the visual system?

Photoreceptors (rods and cones). Rods detect dim light; cones detect bright light and color.
What is the retinal region with the highest cone density and greatest visual acuity?

Fovea. Central retinal pit packed with cones; responsible for sharp central vision.
What is a sensory receptor in terms of transduction and stimulus detection?

A cell that detects stimuli and transduces energy into neural signals. Converts physical/chemical stimuli into electrical signals for the nervous system.
What is the blind spot, and which retinal structure causes it?

No photoreceptors at optic disc where optic nerve exits. The optic disc lacks photoreceptors, creating a vision gap.
Identify the correct visual pathway order from retina to cortex.

Retina → optic nerve → chiasm → tract → LGN → V1. Nasal fibers cross at chiasm; temporal fibers stay ipsilateral.
Which thalamic nucleus relays auditory information to primary auditory cortex?

Medial geniculate nucleus (MGN). Part of the auditory pathway from ear to temporal lobe.
Which thalamic nucleus relays somatosensory information from the body to S1?

Ventral posterolateral nucleus (VPL). Relays touch/proprioception from body below the neck.
Which theory explains pitch coding by location of maximal vibration on the basilar membrane?

Place theory. High frequencies peak at base, low frequencies at apex of basilar membrane.
What type of sensory receptor detects chemicals such as odorants or tastants?

Chemoreceptor. Binds specific molecules to trigger neural signals.
What is the name of the sensory receptor type that detects temperature changes?

Thermoreceptor. Responds to hot or cold stimuli to signal temperature changes.
What type of sensory receptor detects mechanical pressure, vibration, or stretch?

Mechanoreceptors. These receptors transduce physical deformations into neural impulses for touch, pressure, and vibration sensations.
What law states that $I$ is proportional to stimulus intensity $I$ ?

Weber's law: $I/I = k$ . The just noticeable difference is a constant fraction of intensity.
What is the correct neural pathway order for vision from retina to primary visual cortex?

Retina → optic nerve → LGN → primary visual cortex (occipital lobe). LGN is the thalamic relay between retina and V1 in occipital cortex.
Which retinal photoreceptor mediates high acuity and color vision, especially in bright light?

Cones. Three types (S, M, L) enable trichromatic color vision.
Which cortical lobe contains primary somatosensory cortex (S1)?

Parietal lobe (postcentral gyrus). Located in postcentral gyrus, processes touch and body sensations.
What type of sensory receptor detects chemicals (for example, odorants and tastants)?

Chemoreceptors. These receptors bind to specific molecules in the air or food, triggering signals for smell and taste perception.
What is the correct neural pathway order for somatosensation to primary somatosensory cortex?

Peripheral receptors → thalamus → primary somatosensory cortex (parietal). Touch/pressure signals relay through VPL/VPM nuclei of thalamus.
Which thalamic nucleus relays somatosensory information from the face to S1?

Ventral posteromedial nucleus (VPM). Relays touch/proprioception from trigeminal nerve.
Which sensory system uniquely relays to cortex without first synapsing in the thalamus?

Olfaction. Olfactory neurons project directly to the cortex, bypassing thalamus for quick emotional responses.
Which somatosensory receptors detect deep pressure and vibration?

Pacinian corpuscles. Large, rapidly adapting mechanoreceptors sensitive to high-frequency vibrations.
What type of receptor primarily transduces light in the retina?

Photoreceptors (rods and cones). These specialized cells convert light into neural signals for vision.
Which thalamic nucleus is the primary relay for somatosensory information to somatosensory cortex?

Ventral posterolateral nucleus (VPL). Relays body sensations (not face) to primary somatosensory cortex.
What type of sensory receptor detects light in the retina (rods and cones)?

Photoreceptors. Rods and cones in the retina convert light photons into electrochemical signals through phototransduction.
Identify the sensory receptor class that best matches: "detects blood pH and $CO_2$ levels."

Chemoreceptors. Monitor chemical changes in blood and CSF for homeostatic regulation.
What is the correct neural pathway for somatosensation to the primary somatosensory cortex?

Receptors → spinal cord → thalamus → S1 (parietal lobe). Somatosensory signals ascend dorsal columns or spinothalamic tracts to the thalamus then parietal cortex.
Which thalamic nucleus relays visual information to the primary visual cortex?

Lateral geniculate nucleus (LGN). Part of thalamus that processes and relays retinal input to V1.
Where do nasal retinal fibers cross, and what is the name of that structure?

They cross at the optic chiasm. Crossing enables each brain hemisphere to process opposite visual field.
Which receptor type detects chemicals such as odorants or tastants?

Chemoreceptors. Bind specific molecules to trigger conformational changes and signal transduction.
What is transduction in sensory physiology?

Conversion of stimulus energy into neural signals. Physical stimuli are converted to electrical signals neurons can process.
Which structure is the first cortical relay for olfactory information?

Olfactory bulb (then olfactory cortex). Receives direct input from olfactory receptor neurons.
Which thalamic nucleus is the main relay for auditory information to the auditory cortex?

Medial geniculate nucleus (MGN). Thalamic relay receiving input from inferior colliculus before auditory cortex.
What is sensory adaptation?

Reduced receptor response during constant stimulation. Allows filtering of constant stimuli to detect changes.
What does Weber's law state about the just noticeable difference (JND)?

JND is a constant fraction of the original stimulus: $\frac{\Delta I}{I}=k$ . The ratio of change to original intensity remains constant.
Which retinal photoreceptors support color vision and high visual acuity?

Cones. Contain opsins for red, green, or blue light; concentrated in fovea.
Identify the receptor type that detects chemicals such as odorants and tastants.

Chemoreceptors. Detect specific molecules for taste, smell, and internal chemical monitoring.
Which visual photoreceptor is most sensitive in dim light and supports night vision?

Rods. More numerous in periphery; contain rhodopsin for low-light sensitivity.
What type of receptor primarily transduces temperature changes in skin?

Thermoreceptors. These detect hot and cold stimuli through ion channel activation.
What is the primary thalamic relay nucleus for vision before the visual cortex?

Lateral geniculate nucleus (LGN). Thalamic relay with 6 layers processing different visual information types.
Identify the cortical area that receives touch information from the thalamus (VPL/VPM).

Primary somatosensory cortex (postcentral gyrus). Located in parietal lobe, processes tactile sensations from body.
Identify the modality and receptor: a stimulus activates receptors in muscle spindles.

Proprioception; proprioceptors (mechanoreceptors). Muscle spindles detect stretch to sense limb position.
What is the key difference between tonic and phasic sensory receptors?

Tonic adapt slowly; phasic adapt rapidly. Tonic fire continuously; phasic fire only at stimulus onset/offset.
What is the name of the sensory receptor that responds to light in the retina?

Photoreceptor (rods and cones). Specialized cells in retina that convert light into neural signals.
What type of sensory receptor detects temperature changes?

Thermoreceptor. Contains ion channels sensitive to heat or cold.
Which tract carries pain and temperature information from the body to the brain?

Spinothalamic (anterolateral) tract. Crosses at spinal level; synapses in thalamus.
What is the term for the minimum detectable difference between two stimuli $50\%$ of the time?

Difference threshold (just-noticeable difference). The smallest change in stimulus intensity that can be detected half the time.
Which auditory receptor cells convert mechanical vibration into neural signals?

Hair cells in the organ of Corti. Stereocilia bend with basilar membrane movement, opening ion channels.
Which cranial nerve carries olfactory information from the nasal epithelium to the brain?

CN I (olfactory nerve). First cranial nerve directly connects nose to olfactory bulb.
What is the correct sequence of structures that transduce sound in the ear?

Tympanic membrane ossicles oval window cochlea (hair cells). Sound waves mechanically amplified before reaching fluid-filled cochlea.
What is the effect of a lesion at the optic chiasm on the visual field?

Bitemporal hemianopia. Loss of both temporal visual fields from crossing fiber damage.
Which retinal photoreceptors are most sensitive in dim light and support night vision?

Rods. Contain rhodopsin, extremely sensitive to low light.
What thalamic nucleus is the primary relay for visual information before the visual cortex?

Lateral geniculate nucleus (LGN). Thalamic relay station for visual signals en route to V1.
Identify the sensory system that reaches cortex without a thalamic relay as its first synapse.

Olfaction. Projects directly to piriform cortex and limbic structures.
What is sensory transduction?

Conversion of stimulus energy into an electrochemical neural signal. Receptors convert physical stimuli into action potentials.
Which receptor type primarily detects chemicals (smell and taste)?

Chemoreceptors. Olfactory and gustatory receptors detect chemical molecules.
Which statement best matches contralateral processing in somatosensation?

Each hemisphere represents the opposite side of the body. Sensory pathways cross midline, so left brain processes right body.
Which thalamic nucleus relays most sensory information to cortex, excluding olfaction?

Thalamus (sensory relay; olfaction bypasses it initially). All senses except smell pass through thalamus before reaching cortex.
What is the general pathway name for motor commands traveling from the CNS?

Efferent pathway. Carries motor commands away from the brain.
What type of sensory receptor detects tissue damage or potentially harmful stimuli (pain)?

Nociceptor. Free nerve endings that signal potential or actual tissue damage.
What is the primary cortical area that receives somatosensory input from the thalamus?

Primary somatosensory cortex (postcentral gyrus). Located in parietal lobe; organized somatotopically as homunculus.
Which thalamic nucleus relays auditory information to the primary auditory cortex?

Medial geniculate nucleus (MGN). This thalamic nucleus processes frequency and intensity before forwarding to the auditory cortex.
Which retinal region has the highest cone density and greatest visual acuity?

Fovea centralis. This central retinal area has dense cone packing and no rods, optimizing sharpness for focused vision.
Which sensory modality is the key exception that does NOT relay through the thalamus before cortex?

Olfaction (smell). Goes directly to olfactory cortex without thalamic relay.
Which receptor type detects chemicals for smell and taste?

Chemoreceptors. Respond to specific molecules; olfactory receptors in nose, taste buds on tongue.
What is the adequate stimulus for a sensory receptor?

The stimulus modality to which the receptor is most sensitive. Each receptor type evolved to detect specific stimulus types.
Identify the concept: perceived intensity is proportional to $ log(I)$.

Fechner's law. Sensation magnitude increases logarithmically with stimulus intensity.
What is the adequate stimulus of a sensory receptor?

The stimulus type to which the receptor is most sensitive. Each receptor type responds best to its specific stimulus modality.
What is receptive field size, and what does a smaller receptive field imply?

Area sensed by a neuron; smaller fields imply higher spatial acuity. Smaller fields allow finer discrimination of stimulus location.
Which receptor type detects mechanical pressure, vibration, and stretch (touch)?

Mechanoreceptors. Respond to physical deformation; includes Pacinian, Meissner, Merkel, and Ruffini.
Which somatosensory receptors detect skin stretch and sustained pressure?

Ruffini endings. Slowly adapting mechanoreceptors that signal continuous deformation.
Which receptor class is primarily responsible for proprioception in muscles and tendons?

Mechanoreceptors (muscle spindles and Golgi tendon organs). These specialized mechanoreceptors sense body position and muscle tension.
What is sensory transduction in the context of receptor cells and neural signaling?

Conversion of physical/chemical stimulus energy into electrical neural signals. Receptors convert stimulus energy into graded potentials that trigger action potentials.
What is the correct order of information flow in a basic sensory pathway?

Receptor sensory neuron CNS motor neuron effector. Shows the complete reflex arc from stimulus detection to response.
What is the correct neural pathway order for audition from cochlea to primary auditory cortex?

Cochlea → MGN → primary auditory cortex (temporal lobe). MGN (medial geniculate nucleus) is the thalamic relay for hearing.
Which term describes the minimum stimulus intensity detected $50\%$ of the time?

Absolute threshold. The weakest detectable stimulus level, measured psychophysically.
What is the name of the sensory receptor type that detects chemicals (taste and smell)?

Chemoreceptor. Binds specific molecules to trigger neural signals for taste/smell.
What is the difference threshold (just-noticeable difference, JND)?

Smallest detectable difference between two stimuli. The minimum change in stimulus intensity that's noticeable.
Which cortical lobe contains primary visual cortex (V1)?

Occipital lobe. Most posterior lobe, specialized for processing visual information.
What is the name of the sensory receptor type that detects tissue damage or painful stimuli?

Nociceptor. Free nerve endings that signal potential or actual tissue damage.
Which thalamic nucleus relays auditory information to primary auditory cortex?

Medial geniculate nucleus (MGN). MGN in thalamus processes sound before cortical analysis.
What is the key functional difference between rods and cones in human vision?

Rods: dim light; cones: color and high acuity. Rods are sensitive for night vision; cones detect wavelengths for color perception.
What type of sensory receptor detects temperature changes in the environment or body?

Thermoreceptors. These receptors respond to thermal energy changes, activating ion channels to signal hot or cold temperatures.
Which thalamic nucleus relays most auditory information to the auditory cortex?

Medial geniculate nucleus (MGN). Part of the auditory pathway from inferior colliculus to cortex.
What is the function of the lateral geniculate nucleus (LGN)?

Thalamic relay from retina to primary visual cortex. Processes visual signals before sending to V1 in occipital lobe.
Which visual pathway carries retinal signals to primary visual cortex (V1)?

Retina optic nerve LGN optic radiations V1. LGN is the thalamic relay between retina and visual cortex.
Which sensory modality uniquely reaches cortex without first synapsing in the thalamus?

Olfaction (smell). Olfactory bulb projects directly to piriform cortex.
Which thalamic nucleus relays auditory information to the primary auditory cortex?

Medial geniculate nucleus (MGN). Thalamic relay station for auditory processing.
What is sensory transduction?

Conversion of stimulus energy into neural impulses. Physical stimuli become electrical signals in sensory neurons.
What is receptive field in sensory systems?

Region of sensory space that alters a neuron's firing. Defines the area where stimuli can activate a sensory neuron.
Identify the receptor type that detects temperature changes.

Thermoreceptors. Specialized nerve endings that respond to hot and cold stimuli.
Which sensory modality is the major exception that does not relay through the thalamus first?

Olfaction (smell). Goes directly to olfactory cortex, bypassing thalamic relay.
What is the primary sensory cortex for somatosensation (name and lobe)?

Primary somatosensory cortex in parietal lobe. Processes touch, pressure, temperature, and pain.
What is the primary sensory cortex for vision (name and lobe)?

Primary visual cortex (V1) in occipital lobe. First cortical area processing visual information.
Which term describes receptors that respond strongly at stimulus onset or offset?

Phasic (rapidly adapting) receptors. Detect changes in stimulation, not sustained levels.
What term describes the smallest detectable difference between two stimuli $50\%$ of the time?

Just-noticeable difference (difference threshold). The smallest change in stimulus intensity we can perceive.
What is the optic disc, and what perceptual consequence does it create?

Exit of optic nerve; no photoreceptors; creates the blind spot. Axons converge here to form optic nerve; lacks receptors.
What is the correct neural pathway order for somatosensation to primary somatosensory cortex?

Receptors → spinal cord → thalamus → somatosensory cortex (parietal lobe). Touch/pain signals ascend dorsal columns or spinothalamic tracts to VPL nucleus.
What is the correct neural pathway order for vision from retina to primary visual cortex?

Retina → LGN → primary visual cortex (occipital lobe). LGN (lateral geniculate nucleus) is the thalamic relay for vision.
Which retinal photoreceptor is specialized for dim light and high sensitivity?

Rods. Contains rhodopsin for scotopic vision; no color discrimination but very sensitive.
What is the key distinction between afferent and efferent neural pathways?

Afferent: sensory to CNS; Efferent: motor from CNS. Direction of signal flow relative to central nervous system.
What thalamic nucleus is the primary relay for auditory information before auditory cortex?

Medial geniculate nucleus (MGN). Thalamic relay station for auditory signals to auditory cortex.
Which sensory modality reaches primary cortex without an initial thalamic relay?

Olfaction. Smell signals go directly to olfactory cortex, then to thalamus.
Which thalamic nucleus relays somatosensory information to the primary somatosensory cortex?

Ventral posterior nucleus (VPL/VPM). VPL handles body sensations and VPM facial, relaying somatotopically to the cortex.
What is the correct neural pathway for olfaction from receptors to primary olfactory cortex?

Olfactory epithelium → bulb → tract → olfactory cortex. Odorants bind receptors, signaling through glomeruli and tracts to cortical areas for scent identification.
What is the definition of an adequate stimulus for a sensory receptor?

Stimulus type the receptor is most sensitive to. Each receptor type responds best to its specific stimulus modality.
Identify the visual photoreceptor specialized for low-light sensitivity and motion detection.

Rods. Contain rhodopsin for scotopic vision; more numerous in peripheral retina.
What is the fovea, and what visual function is it specialized for?

Retinal region of highest cone density for maximal visual acuity. Central retinal pit packed with cones for sharp central vision.
What is sensory transduction in the context of sensory receptors?

Conversion of stimulus energy into neural signals. Receptors transform environmental energy forms into action potentials that the nervous system can process.
Which tract carries fine touch, vibration, and proprioception from the body to the brain?

Dorsal column–medial lemniscus pathway. Crosses at medulla; precise tactile discrimination.
Which structure is the primary relay for most sensory information before cortex (excluding olfaction)?

Thalamus. All sensory pathways except smell synapse here before reaching cortex.
Which somatosensory pathway carries fine touch and proprioception to cortex?

Dorsal columnmedial lemniscus pathway. Crosses at medulla; relays through VPL thalamus to S1.
What is the name of the retinal region with the highest cone density and greatest visual acuity?

Fovea. Central retinal pit packed with cones for sharp central vision.
What is the term for a stimulus that is just strong enough to be detected $50\%$ of the time?

Absolute threshold. The weakest stimulus intensity detectable half the time under ideal conditions.
Which term describes receptors that maintain firing during a sustained stimulus?

Tonic (slowly adapting) receptors. Continue signaling throughout stimulus duration.
Identify the receptor type that responds to light in the retina.

Photoreceptors (rods and cones). These specialized cells in the retina convert light into neural signals.
What is the difference between an absolute threshold and a difference threshold?

Absolute: minimum detected; Difference: minimum change detected (JND). Absolute is the weakest detectable stimulus; difference is the smallest noticeable change.
What is the primary cortical region for somatosensation (touch and proprioception)?

Primary somatosensory cortex (postcentral gyrus). This parietal area receives and maps touch, pressure, and position inputs somatotopically.
What is a sensory receptor in terms of transduction and the type of input it detects?

A cell that transduces physical/chemical stimuli into neural signals. Converts environmental energy into electrical signals neurons can process.
What type of sensory receptor transduces light in the retina?

Photoreceptor (rods and cones). Rods detect dim light; cones detect color and bright light.
What is sensory adaptation, and what happens to firing rate during constant stimulation?

Reduced responsiveness; firing rate decreases over time with constant input. Neurons stop responding to unchanging stimuli to filter out irrelevant information.
What does Weber's law state about the just-noticeable difference (JND) and stimulus magnitude?

JND is proportional to baseline intensity: $\frac{\Delta I}{I}=k$ . The ratio of change to baseline remains constant across intensities.
What is the difference between an absolute threshold and a difference threshold?

Absolute: minimum detectable; Difference: minimum detectable change (JND). Absolute is detection; JND is discrimination between stimuli.
What type of sensory receptor detects mechanical pressure, vibration, or stretch?

Mechanoreceptor. Responds to physical deformation of the receptor membrane.
What is the definition of a receptive field for a sensory neuron?

Region of sensory space that alters that neuron's firing. Stimulation within this area changes the neuron's activity.
What is the functional difference between tonic and phasic sensory receptors?

Tonic: sustained; phasic: rapidly adapting to change. Tonic fires continuously; phasic fires only when stimulus changes.
What are the five basic taste modalities detected by human gustatory receptors?

Sweet, sour, salty, bitter, umami. These modalities are detected by specialized taste buds on the tongue that respond to distinct chemical compounds in food.
What is the correct neural pathway order for conscious touch from body to cortex?

Receptor → afferent neuron → thalamus → cortex. Standard sensory pathway with thalamic relay before cortex.
What is the primary cortical region for audition (sound processing)?

Primary auditory cortex (superior temporal gyrus). This temporal region analyzes sound features like pitch and rhythm from thalamic inputs.
Which cranial nerve carries olfactory sensory information from the nasal epithelium?

Cranial nerve I (olfactory nerve). Axons pass through cribriform plate to synapse in olfactory bulb.
Identify the correct pathway order for somatosensation to cortex.

Receptor → afferent neuron → thalamus → primary somatosensory cortex. Touch signals ascend through spinal cord to brain via this pathway.
Identify the modality and receptor: a stimulus bends stereocilia in the cochlea.

Hearing; mechanoreceptors (hair cells). Sound waves deflect hair cells' stereocilia in organ of Corti.
What is sensory adaptation in receptor responses to a constant stimulus?

Decreased receptor firing during sustained stimulation. Allows us to ignore constant stimuli like clothing on skin.
Which thalamic nucleus relays auditory information to the primary auditory cortex?

Medial geniculate nucleus (MGN). Thalamic relay for auditory signals from inferior colliculus to A1.
What is the key functional difference between rods and cones?

Rods: low light, low acuity; cones: color, high acuity. Rods excel in darkness; cones provide sharp, colorful daylight vision.
What does Weber's law state about the JND relative to stimulus intensity?

JND is a constant fraction of baseline intensity. Larger stimuli need proportionally larger changes to be noticed.
What is the term for conversion of physical stimulus energy into neural signals?

Sensory transduction. Converts physical stimuli (light, sound, touch) into electrical neural impulses.
What thalamic nucleus relays somatosensory information from the face to cortex?

VPM (ventral posteromedial) nucleus. Face sensations relay through this thalamic nucleus.
Which retinal photoreceptor is most sensitive in dim light and supports night vision?

Rods. These photoreceptors contain rhodopsin, which is highly sensitive to low light, enabling scotopic vision.
What is the difference between absolute threshold and difference threshold?

Absolute: minimum detectable; Difference: minimum detectable change. Absolute is detection; difference is discrimination between stimuli.
Identify the receptor type that detects mechanical deformation such as touch, pressure, and vibration.

Mechanoreceptors. Respond to physical distortion of cell membrane.
What type of sensory receptor detects chemicals, supporting taste and smell?

Chemoreceptor. Responds to specific molecules in taste buds and olfactory epithelium.
What is the optic chiasm, and what key axons cross there?

Junction where nasal retinal fibers decussate to the opposite hemisphere. Creates binocular visual fields; temporal fibers remain ipsilateral.
What inner ear structures primarily detect head rotation and linear acceleration for balance?

Semicircular canals and otolith organs (utricle, saccule). Canals detect rotation via fluid movement, while otoliths sense gravity and acceleration via crystal displacement.
Identify the correct order of the visual pathway from retina to primary visual cortex.

Retina → optic nerve → LGN → optic radiations → V1. Visual signals relay through thalamus before reaching cortex.

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