Neurobiology -

What is transduction in the context of sensory systems?

The conversion of physical stimuli into electrical signals in sensory receptors.

What are photoreceptors and their main components?

Photoreceptors are specialized cells in the retina that detect light, consisting of rhodopsin in rods and photopsin in cones.

How do photoreceptors respond to light and dark?

In the dark, photoreceptors are depolarized and release glutamate; in light, they hyperpolarize and reduce glutamate release.

What is the role of retinal in phototransduction?

Retinal changes shape when it absorbs light, leading to a conformational change in opsin and initiating the phototransduction cascade.

What is the function of the cornea in the eye?

The cornea is the primary refractive element that shapes light entering the eye.

What is the process of accommodation in the lens?

Accommodation is the adjustment of the lens shape to focus light on the retina, becoming rounder for closer objects and flatter for distant ones.

What is the significance of the optic chiasm?

The optic chiasm is where the nasal hemifield fibers decussate, allowing visual information from each visual hemifield to be processed in the contralateral hemisphere.

What is the push-pull system in ganglion cells?

The push-pull system refers to the on/off center organization of ganglion cells that enhances contrast in visual processing.

What is tonotopic organization in the auditory system?

Tonotopic organization refers to the arrangement of auditory structures according to frequency, with different regions responding to specific sound frequencies.

How do hair cells in the cochlea transduce sound?

Hair cells convert mechanical movements from sound waves into electrical signals through the opening of ion channels.

What are the two main pathways for exteroceptive somatosensation?

The dorsal column medial lemniscus pathway for touch and proprioception, and the anterolateral pathway for pain and temperature.

What is the role of GABA in the visual system?

GABA is used by horizontal cells to create an opponent center-surround organization in the retina.

What is the function of the angular gyrus in the auditory system?

The angular gyrus is involved in auditory scene analysis and integrates auditory and visual information.

What is the difference between fast and slow receptors in somatosensation?

Fast receptors respond only to the onset of a stimulus, while slow receptors respond continuously to ongoing stimuli.

What is the significance of the fovea in the retina?

The fovea is the area of the retina with the highest concentration of photoreceptors, providing the sharpest vision.

What is the function of the vestibular system?

The vestibular system provides information about balance and spatial orientation.

What is the role of the cochlear nuclei in auditory processing?

The cochlear nuclei receive auditory nerve input and begin the processing of sound information in the brain.

What is the missing fundamental in pitch perception?

The missing fundamental is a phenomenon where the brain perceives a pitch even when the fundamental frequency is absent.

What is the relationship between glutamate and Na+ channels during phototransduction?

Increased glutamate release during phototransduction opens more Na+ channels, contributing to depolarization.

What is the central proprioceptive pathway?

The central proprioceptive pathway is the dorsal column medial lemniscus (DCML), which decussates in the dorsal column nuclei.

What is the role of the inferior colliculi in auditory processing?

The inferior colliculi integrate auditory information and are involved in sound localization.

What is the function of the primary auditory cortex (A1)?

A1 processes auditory information and is surrounded by secondary auditory regions for further analysis.

What is the role of the ciliary muscles in the eye?

Ciliary muscles adjust the shape of the lens for focusing light on the retina during accommodation.

What is the significance of the blind spot in the retina?

The blind spot is the area where the optic nerve exits the eye, lacking photoreceptors and thus unable to detect light.

What is the primary function of the cortex in relation to sensory processing?

The cortex primarily cares about processing quick things.

What type of mechanism is involved in the adaptation of sensory receptors?

There is a push/pull mechanism between slow and fast adapting receptors, except for proprioception.

What is the role of mechanoreceptors in sensory transduction?

Mechanoreceptors allow for Na+ influx.

How do pain and temperature receptors function in terms of ion influx?

They function through Ca2+ influx.

What are the two types of taste transduction mechanisms?

Direct and indirect mechanisms.

What ions are involved in the direct transduction of salty and sour tastes?

Salty taste involves Na+ ions, while sour taste involves H+ ions.

How do salty tastants cause depolarization in taste cells?

Salty tastants permeate amiloride-sensitive Na+ channels, directly depolarizing and causing large action potentials.

What is the mechanism of sour tastants in taste transduction?

Sour tastants permeate amiloride-sensitive Na+ channels and block K+ channels, leading to depolarization.

What type of receptors do bitter, sweet, and umami tastants bind to?

They bind to G-protein coupled receptors.

What is the role of IP3 in the indirect transduction pathway for taste?

IP3 elevates internal Ca++, causing the release of Ca from internal stores and opening unique Ca-activated Na channels.

What cranial nerves are involved in the central taste pathways?

The 7th, 9th, and 10th cranial nerves.

Where does flavor perception occur in the brain?

Flavor perception occurs in the ventrolateral prefrontal cortex (VLPFAC).

What are the three types of papillae on the tongue that contain taste buds?

Vallate, foliate, and fungiform papillae.

How many taste cells are typically found in a taste bud?

A taste bud contains 50-100 taste cells.

What is the lifespan of taste cells?

Taste cells are replaced every couple of weeks, with about 10% replaced per day.

What is the primary role of olfactory sensory neurons (OSNs)?

OSNs detect odorants in the olfactory epithelium.

What is unique about the olfactory system's pathway to the cortex?

It is the only sensory system that does not pass through the thalamus on its way to the cortex.

What type of molecules can the olfactory system detect?

The olfactory system can detect small volatile molecules like alcohols and fatty acids, as well as larger complex molecules like musks and steroids.

What is the function of odorant binding proteins in the olfactory epithelium?

They enhance the concentration of odorants in the mucus layer.

What happens to odorants after they bind to receptors in the olfactory system?

Odorants diffuse away or are broken down by enzymes, and cAMP activates processes that terminate transduction.

What is the role of calcium in the indirect transduction of taste?

Calcium is involved in depolarization and neurotransmitter release in taste cells.

What is the role of olfactory receptor proteins in the olfactory system?

Olfactory receptor proteins (ORPs) are not the same as transmembrane domain G protein-coupled receptors; each olfactory sensory neuron (OSN) typically expresses only one ORP gene, allowing for the relay of information for tens of thousands of perceptive odors.

How does the olfactory system represent specific odors?

The olfactory system uses a population code to represent specific odors, as activation patterns for different odors overlap extensively but remain unique for each odorant.

What is the difference between adaptation and desensitization in sensory systems?

Adaptation is a fast response that occurs only at the beginning of stimulus exposure, while desensitization is a slower change in response to multiple stimuli.

What is the main current involved in olfactory transduction?

The main currents involved in olfactory transduction are depolarizing sodium (Na+) and calcium (Ca++) currents, along with an outward chloride (Cl-) current.

What is the function of the olfactory bulb?

The olfactory bulb processes input from olfactory sensory neurons (OSNs) and contains glomeruli where OSNs expressing the same olfactory receptor converge.

What is the significance of glomeruli in the olfactory bulb?

Each glomerulus is an anatomical and functional unit that processes input from OSNs expressing a single olfactory receptor, contributing to odor mapping and processing.

What are the two major pathways of the visual system?

The dorsal pathway ('where' information) processes motion and spatial awareness, while the ventral pathway ('what' information) processes color and form.

What is the role of the lateral geniculate nucleus (LGN) in vision?

The LGN is organized into six distinct layers, receiving input from retinal ganglion cells and relaying visual information to the primary visual cortex (V1).

What are the primary functions of the cerebellum?

The cerebellum is involved in motor coordination, timing, and learning new motor skills, as well as adapting movements to sensory feedback.

What is the difference between M cells and P cells in the visual system?

M cells are large, have large receptive fields, and are optimized for motion detection, while P cells are smaller, have fine resolution, and are sensitive to color contrasts.

What is the function of the primary motor cortex (M1)?

M1 is the major point of convergence for cortical sensorimotor signals and is responsible for executing voluntary movements.

What is the role of mirror neurons?

Mirror neurons are active during both the execution of an action and the observation of the same action, potentially contributing to learning by imitation.

What is the difference between fast and slow adapting mechanoreceptors?

Fast adapting mechanoreceptors, like Meissner's corpuscles, respond quickly to stimuli but stop firing with sustained pressure, while slow adapting mechanoreceptors, like Merkel's disks, continue to respond to constant pressure.

What are the five basic tastes?

The five basic tastes are sweet, sour, salty, bitter, and umami.

How do dermatomes function in the sensory system?

Dermatomes are areas of the body innervated by the dorsal roots of a given segment of the spinal cord, with some overlap allowing for sensation even if one nerve is damaged.

What is proprioception and how is it achieved?

Proprioception is the sense of body position and movement, achieved through muscle spindles and Golgi tendon organs that provide feedback on muscle length and tension.

What is the role of the vestibular system?

The vestibular system monitors head position and movement, contributing to balance and spatial orientation.

What is the difference between sensation and perception?

Sensation is the physical interaction of a stimulus with a sensory receptor, while perception is the conscious awareness and interpretation of that sensation.

What is the duplex theory in vision?

The duplex theory states that rods and cones serve different functions in vision, with rods being responsible for low-light (scotopic) vision and cones for color (photopic) vision.

What is the function of the arcuate fasciculus?

The arcuate fasciculus connects Wernicke's area and Broca's area, facilitating language comprehension and production.

What is the role of the angular gyrus?

The angular gyrus is involved in language processing and is associated with dyslexia when damaged.

What is the function of the primary auditory cortex?

The primary auditory cortex processes auditory information and is involved in sound localization and discrimination.

What is the role of the basal ganglia in motor control?

The basal ganglia facilitate and inhibit motor programs, influencing the initiation and execution of movements.

What is the function of the spinal cord in motor control?

The spinal cord integrates sensory inputs and motor outputs, coordinating reflexes and voluntary movements.

What is the significance of the patellar tendon reflex?

The patellar tendon reflex is a monosynaptic stretch reflex that helps maintain posture and balance by preventing excessive stretching of the muscle.

What is the role of the sensory association cortex?

The sensory association cortex integrates sensory information from multiple modalities to guide motor actions.

What is the difference between intrinsic and extrinsic space hypotheses in motor control?

The intrinsic space hypothesis suggests that M1 controls movements muscle by muscle, while the extrinsic space hypothesis posits that M1 activates groups of muscles for coordinated movement.

What is the function of the cingulate cortex?

The cingulate cortex is involved in emotion regulation, decision-making, and the integration of sensory and emotional information.

What is the role of the prefrontal cortex in sensorimotor function?

The prefrontal cortex is involved in planning and decision-making, integrating sensory information to guide actions.

What is the function of the superior colliculus?

The superior colliculus is involved in visual reflexes and the coordination of eye movements.

What is the significance of the central pattern generator?

The central pattern generator is a neural circuit in the spinal cord that generates rhythmic patterns of motor activity, such as walking.

What is the role of the cerebellum in motor learning?

The cerebellum is crucial for adapting and refining motor skills through practice and sensory feedback.

What is the difference between agonist and antagonist muscles?

Agonist muscles are those that contract to produce a movement, while antagonist muscles oppose that movement.

What is the role of Renshaw cells?

Renshaw cells are inhibitory interneurons that provide recurrent collateral inhibition to motor neurons, helping to regulate muscle activity.

What is the significance of the neuromuscular junction?

The neuromuscular junction is where motor neurons release acetylcholine to activate muscle fibers, leading to contraction.

What is the function of the Golgi tendon organs?

Golgi tendon organs provide feedback on muscle tension, helping to prevent excessive force during muscle contractions.

What is the difference between fast-twitch and slow-twitch muscle fibers?

Fast-twitch fibers are larger, fatigue quickly, and are used for short bursts of power, while slow-twitch fibers are smaller, more endurance-oriented, and have a constant blood supply.

What is the role of the hippocampus in memory?

The hippocampus is critical for the formation of new memories and spatial navigation.

What is the significance of the amygdala in emotion?

The amygdala is involved in processing emotions, particularly fear and pleasure, and plays a role in emotional memory.

What is the function of the thalamus?

The thalamus acts as a relay station for sensory information, directing it to appropriate areas of the cortex for processing.

What is the role of the hypothalamus?

The hypothalamus regulates homeostasis, including temperature, hunger, thirst, and circadian rhythms.