Behavioral Neuroscience Exam 2

Common feature of neuronal and hormonal communication

Both secretory events (neuron produces particular transmitter chemicals and releases them, just as an endocrine gland produces and releases hormones)

How do hormone effects differ from neurotransmitters?

Hormone effects are slower and travel through the bloodstream rather than across synapses. Hormone effects are longer lasting. Main effect of hormones is to regulate bodily functions, while the main function of neurotransmitters is to transmit signals within the nervous system

Importance of cholesterol

Basis from where steroid hormones are derived

How steroid hormones affect cells

Specific actions determined by specific receptors that reside inside target cells. Acts as a transcription factor, which alters the rate of expression of part. genes. This action results in increases or decreases in production of proteins encoded by regulated genes

Pancreas hormone and glucose

Insulin is released from pancreas after glucose enters the bloodstream. Insulin causes glucose to enter muscle and fat cells. As the level of glucose in the blood falls, the pancreas secretes less insulin

Hormonal control from brain to glands

Pituitary gland is the "master gland," controlling hormone release from several other endocrine glands

Estrogens are made from...

Neurosteroids

What converts testosterone into estrogens?

Aromatase

What hormones are released by the posterior pituitary?

Oxytocin and Antidiuretic hormone (ADH/Vasopressin)

Neurohypophysis (posterior pituitary)

posterior lobe of the pituitary gland

What hormone is released during non-REM sleep?

Growth hormone (GH)

Growth hormone (GH)

Also known as somatotropin, acts through the body to influence the growth of cells and tissue by affecting protein metabolism

Cortisol and corticosterone release

Released from the adrenal cortex when ACTH from anterior pituitary stimulates the adrenal gland, ACTH release is controlled by CRH from hypothalamus, and the hormones provide negative feedback to the hypothalamus and pituitary

What hormones are released by the adrenal medulla?

epinephrine and norepinephrine

What hormones are found only in males?

NONE

Ovarian hormones

Estrogen and progesterone. Release is controlled by LH and FSH, which are controlled by GnRH

Differentiating between sensory modalities

We differentiate through different receptors for each sensory system and through direct pathways along each system

Labeled lines theory

a theory of sensory coding in which each nerve fiber carries a particular stimulus quality

Mechanical stimulation of a Pacinian corpuscle

A stimulus to the corpuscle produces a graded electrical potential with amplitude directly proportional to the strength of the stimulus. When the potential is large enough, the receptor reaches threshold and generates an action potential

Sensory transduction

Conversion of electrical energy from a stimulus into a change in membrane potential in a receptor cell

Tonic receptor

Frequency of action potentials declines slowly or not at all as stimulation is maintained

Phasic receptor

Frequency of action potentials drops rapidly as stimulation is maintained

Evolutionary advantage of sensory adaptation

Prevents the nervous system from being overwhelmed by stimuli that offer very little "news" about the world. It allows for us to only notice "important" stimuli

Most sensory pathways...

Pass through regions of the thalamus

Which receptors are fast-acting?

Pacinian corpuscles and Meissner's corpuscles

Pacinian corpuscles

respond to deep pressure and vibration

Meissner's corpuscles

respond to light touch

Ruffini endings

respond to stretch

Merkel discs

fine touch receptors

What info do A-alpha fibers carry?

proprioception

What info do A-beta fibers carry?

touch and pressure

What info do A-delta fibers carry?

pain and temperature

What info do C fibers carry?

Temp, pain, itch

Dorsal column system

Delivers touch info to the brain. Receptors send axons via the dorsal column of the spinal cord where they synapse on dorsal column nuclei in the medulla. Axons from neurons in medulla cross the midline and go to the thalamus. Outputs of thalamus are directed to primary somatosensory cortex

Why is pain perception adaptive?

It causes withdrawal from harmful stimuli, promotes recovery behaviors and signals others that help may be needed

Sensory cortical maps

Somatotopic maps in the somatosensory cortex where different body parts are represented in specific cortical areas with more sensitive areas having larger representation

Mediating pain perception

Mediated by the spinothalamic (anterolateral) pathway, which carries nociceptive info from the spinal cord to thalamus and cortex using glutamate and substance P

Which afferent fibers carry nociceptor information?

A-delta fibers and C fibers

Social hurt and physical pain

Social rejection and physical pain activate the same brain regions, especially the anterior cingulate cortex, showing that social hurt uses the same emotional pain system as physical pain.

Modulating pain signaling

Modulated by descending pathways from the brain through periaqueductal gray and raphe nuclei, which release endogenous opiods that inhibit pain transmission in the spinal cord

Hertz

Cycles per second, measure of frequency

Ossicles

bones of the middle ear: malleus, incus, stapes

Malleus

"Hammer," middle ear bone that's connected to tympanic membrane

Incus

"Anvil," middle ear bone situated between the malleus and stapes

Stapes

"Stirrup," middle ear bone that's connected to the oval window

Stereocilia

Cell that's undifferentiated and can take on the fate of any cell that a donor organism can produce. Each hair cell has 50-200 stereocilia. Heights of the stereocilia increase progressively across the hair cells, so the tops form a slope

Sounds that deflect the base of basilar membrane

High-frequency sounds

Mapping in auditory cortex

Tonotopic organization

Tonotopic organization

the spatial arrangement of sensory neurons based on the sound frequencies they respond to

Mechanisms of pitch perception

Place coding and temporal coding

Place coding

The perception of higher-pitched sounds is a result of the location on the basilar membrane where hair cells are stimulated by sound waves of varying higher frequencies.

Temporal coding

The perception of lower-pitched sounds is a result of the rate at which hair cells are stimulated by sound waves of lower frequencies.

Semicircular canals

three fluid-filled canals in the inner ear responsible for our sense of balance

Ampulla

contains hair cells for rotation detection

Cupula

a gelatinous mass found in the ampulla of the semicircular canals; bends hair cells

Utricle

A small, fluid-filled sac in the vestibular system above the saccule that detects head tilt and linear acceleration

Saccule

A small, fluid-filled sac under the utricle in the vestibular system that detects vertical acceleration and position

Otoliths

Crystals that detect gravity and movement

circumvallate papillae

large papillae with taste buds- on back of tongue

foliate papillae

on side walls of tongue

Fungiform papillae

Located on the front (tip and middle) of the tongue

Basic tastes

Sweet, sour, salty, bitter, and umami

Umami

Savory/meaty taste

How are sweet tastes detected?

Detected by T1R1 & T1R3 receptors (GPCRs)

How are sour tastes detected?

Hydrogen ions from acids enter through proton channels

How are salty tastes detected?

Sodium ions enter ion channels

How are bitter tastes detected?

T2R receptors (GPCRs)

How are umami tastes detected?

amino acids - g protein activated on T1R1 receptors but second messenger is unknown

Detecting tastes and the tongue

All areas of the tongue with taste buds can detect all five tastes. Taste information travels from taste receptor cells through cranial nerves to the brainstem, thalamus and gustatory cortex.

Cranial nerves that carry taste information

facial (VII), glossopharyngeal (IX), vagus (X)

The olfactory bulb does not project to...

Thalamus

Structure of olfactory receptor cell

Has a long apical dendrite with a dendritic knob and a cilia in the mucus, and a thin axon that passes through the cribriform plate to the olfactory bulb

Humans and VNO

Humans may have a vestigial vomeronasal organ, but most evidence suggests it is not functional, and pheromone detection in humans likely occurs through the main olfactory system instead.

What is measured in nanometers?

Wavelengths

Accomodation

As the degree of contraction on the ciliary muscles varies, the lens focuses images of nearer or farther objects so that they form sharp images on the retina

Cells of the retina

photoreceptors, bipolar cells, ganglion cells, horizontal cells, amacrine cells

Photoreceptors

Neural cells in the retina that respond to light (Rods & cones)

Rods

Most active in low light levels

Cones

Detects color

Bipolar cells

Class of interneurons that receive info from photoreceptors and pass the info to retinal ganglion cells

Ganglion cells

Class of cells in the retina whose axons form the optic nerve. CONDUCTS ACTION POTENTIALS

Horizontal cells

Specialized retinal neurons that contact both the receptor cells and bipolar cells

Amacrine cells

Specialized retinal neurons that contact both the bipolar cells and ganglion cells and are especially significant in inhibitory interactions within the retina

Chemical in rods

Rhodopsin: Responds to light

Where are cones concentrated?

Center of the retina called the macula

Visual pathway in the brain

Retina; optic nerve; optic chiasm; optic tract; lateral geniculate; optic radiations; striate and primary visual cortices.

How to remember the visual pathway?

RNCTLGNRSP. Really Nice Cats Talk Like Good Noodles Really Sweet Pets

Center/Surround cell responses

On-center/Off-surround and off-center/off-surround: Center and surround are ALWAYS antagonistic (opposite)

Lateral inhibition

Phenomenon by which interconnected neurons inhibit their neighbors, producing contrast at the edges of neurons

Area V5

An early part of the dorsal "where" stream. In monkeys, all neurons in area V5 respond to motion. Moving stimuli also evoke responses in human area V5

Representation in primary visual cortex

AKA striate cortex or area 17. Region of the occipital lobe where most visual info first arrives in the cortex. The stripe represents layer IV of the cortex, where the optic radiation fibers arrive. Information from two eyes converges on cells beyond layer IV.

Relative number of receptors

~120 million rods, ~6 million cones

Why is myopia more common?

Indoor lighting may be the cause

Why is there a difference between hurting yourself and feeling the pain?

The delay occurs because pain is carried by two different types of sensory neurons. 1. A-delta fibers: fast, myelinated, sharp immediate pain. 2. C fibers: slow, unmyelinated, dull, aching pain. When you get hurt, A delta sends a quick signal, C fibers send a second signal. The signals must travel to the spinal cord, then the thalamus, then to the somatosensory cortex before you consciously feel pain. So the delay happens because neural signals take time to travel and because slow C fibers transmit pain more slowly.

Describe how auditory stimuli are processed and compared between the 2 ears to provide spatial localization of sounds, and identify the level of the nervous system where this occurs

Auditory stimuli are processed by comparing the differences in the time and intensity of sound arriving at each ear. Sounds reach the closer ear slightly earlier and are slightly louder than in the farther ear, and the brain uses these differences to determine the location of the sound. This comparison occurs in the superior olivary nucleus in the brainstem, which is part of the central nervous system and is the first place where input from both ears is combined.

Compare gustatory and olfactory systems

The gustatory system and olfactory system are both chemical senses, but they use different receptor types and pathways. The gustatory system uses taste receptor cells located in taste buds on the tongue, which respond to sweet, sour, salty, bitter, and umami tastes. The olfactory system uses olfactory receptor neurons located in the olfactory epithelium in the nose that detect airborne odor molecules. A major difference is that receptors are modified epithelial cells, while olfactory receptors are actual neurons and olfactory information initially bypasses the thalamus before reaching the cortex.

Identify and discuss how the neural mechanisms work that produce edge perception from visual inputs

Edge perception is produced through a process called lateral inhibition in the retina. When light stimulates photoreceptors, horizontal cells inhibit neighboring cells, which increase the contrast between light and dark areas. This makes edges and borders appear sharper and more defined. This process begins in the retina and continues in the primary visual cortex, where edges and lines are further processed.

Give an overview of the idea there are subdivisions of cortical visual systems that can be divided into "what" and "where" streams of visual information processing

The visual system is divided into two main cortical processing streams called ventral stream and the dorsal stream. The ventral stream, know as the "what" pathway, runs from the occipital lobe to the temporal lobe and is responsible for object recognition, including shape, color, and faces. The dorsal stream, know as the "where" pathway runs from the occipital lobe to the parietal lobe and is responsible for spatial location, movement, and guiding actions. Together, these two pathways allow us to both identify objects and understand where they are located in space.