PSY290 - Behavioral Neuroscience FINAL EXAM (UofT) | Quizlet

circadian rhythm

Refers to physiological changes that follow a 24-hour cycle, responding to light or darkness in the environment.

Affects hormone levels, sleep-wake, body temperature, etc.

All land animals coordinate their behavior according to this daily rhythm.

free-running period

The period of a biological rhythm in the absence of external environmental cues.

Continuously shifts, as if "looking" for a new source to entrain to.

Note: light is the cue that animals use to synchronize with the environment, but the clock can still run without being updated.

suprachiasmatic nucleus (SCN) - hypothalamus

The 'master clock' of mammals - located in a tiny region of the ________. Sits directly above the optic chiasm (since light is an important part of entraining the clock).

Lesions of this region abolish circadian rhythmicity, transplantation restores it (free-running period matches that of the donor)

retinohypothalamic pathway

Specialized retinal ganglion cells which directly project to the suprachiasmatic nucleus - an important part of entraining circadian rhythm.

melanopsin

A light-sensitive photopigment expressed by the retinal ganglion cells in the retinohypothalamic pathway.

transcription-translation feedback loop (TTFL)

A rhythmic feedback loop involving clock genes, occurring within the SCN.

Cry and Per genes form a protein complex which inhibits the transcription of more Per and Cry.

(i.e., when protein concentration is low, transcription is fast, when high, transcription is slow).

When the retinohypothalamic pathways releases glutamate onto SCN cells, transcription of Per increases. This is how light entrains the molecular clock.

beta waves

Smaller and faster brain waves (13-30Hz), typically indicating wake consciousness.

alpha waves

Relatively slow (8-12Hz) brain waves of a relaxed, but still awake state (e.g., eyes closed trying to sleep). Interspersed within higher frequency beta waves. Present during stages 1 and 2 of sleep.

delta waves

High amplitude, slow (1-2Hz) waves that indicate slow wave sleep (SWS). Present during stages 3 and 4 of sleep.

More prominent during the first few sleep stage cycles.

Much less prominent with aging.

rapid eye movement (REM)

A stage of sleep that occurs after after cycling from S2 -> S3 -> S4 -> S3 -> S2 -> ___. Eyes move rapidly, with small-amplitude, high-frequency waves. Associated with vivid dreams.

Occurs more frequently during the later sleep stage cycles.

Stimulates the cholinergic system (increase cortical activity) and inhibits spinal motor neurons, i.e., active brain; no muscle contraction.

reticular activating system

Located in the upper brain stem; responsible for maintenance of consciousness, specifically one's level of arousal. Determines wakefulness.

basal forebrain

Contains cholinergic neurons.

Activated by the reticular formation, this structure sends ACh throughout the cortex to promote wakefulness.

During sleep this structure is inactive

tuberomammillary nucleus

A cluster of histamine producing neurons.

Histamine promotes arousal, so inhibiting this structure promotes sleep.

hypocretin neurons

Neurons located in the hypothalamus, activity of these neurons is required for wakefulness.

Loss of these neurons can result in narcolepsy.

ligands

A molecule that binds specifically to a receptor site of another neuron.

endogenous ligands

Ligands (i.e., molecules that bind to receptor sites) which occur naturally within the body (e.g. serotonin)

exogenous ligands

Ligands (i.e., molecules that bind to receptor sites) which are introduced from outside the body.

Typically similar to naturally occurring ligands, binding to their receptor sites (e.g., LSD is similar to serotonin so it can bind to serotonin receptors).

agonists

Drugs that increase receptor activity (i.e., activate receptors)

antagonists

Drugs that block the action of an agonist/natural ligand

competitive

A type of agonist/antagonist that binds to the same receptor site as a natural ligand

non-competitive

A type of agonist/antagonist which binds to modulatory sites on the receptor not targeted by natural ligands

nicotine

(Drug - stimulant) An ACh receptor agonist, acts to enhance the release of a variety of NT's (DA, NE, GLU, GABA, ACh).

cocaine

(Drug - stimulant) Acts on the dopamine reward pathway, blocking reuptake.

Also influences norepinephrine and serotonin systems, resulting in intense alertness and feelings of well-being.

amphetamines

(Drug - stimulant) Acts on the dopamine reward pathway by increasing the amount of dopamine released into the synaptic cleft.

Can increase the amount of dopamine even without an AP.

opiates

(Drug - depressant) Exogenous agonists of the receptors for enkephalins and endorphins, which can be found in the VTA, nucleus accumbens, PAG, and spinal cord.

In the PAG specifically, receptors are acted on which suppresses the perception of pain.

benzodiazepines

(Drug - depressant) Excellent anticonvulsant, sedative, and relaxant effects.
Includes Xanax, Librium, Valium

tympanic membrane

AKA the eardrum. Vibrates when hit with soundwaves, transferring the vibrations to a solid medium via the bone structures behind it

ossicles

Three tiny bones in the middle ear connected to the tympanic membrane.
Sound vibrations are amplified (x20) and transferred to the oval window of the cochlea.

cochlea

A snail shaped tube filled with fluid which carries sound vibrations. Contains three fluid-filled chambers.

Organized tonotopically, higher frequencies stimulate hair cells close to the oval window.

Thus, the source of the APs informs the auditory cortex of the pitch.

tectorial membrane

A membrane located above the basilar membrane in the cochlea; serves as a shelf against which the cilia of the auditory hair cells move

basilar membrane

A structure that runs the length of the cochlea in the inner ear and holds the stereocilia

stereocilia

Hair-like extensions on the tips of hair cells in the basilar membrane of the cochlea. When flexed, opens mechanosensory ion channels called TRPA1 which releases NTs (not via AP).

Note: The actual auditory nerves connect to the bottom of the hair cell, those pick up the NTs and fire AP's toward the auditory cortex.

cochlear nuclei - medulla

A cluster of cells in the _______ which innervate the left and right superior olives

Note: They innervate the contralateral olive more than the ipsilateral olive - i.e., this is where the crossover occurs

auditory neural circuit

Cochlear nuclei -> superior olives -> inferior colliculus -> medial geniculate nucleus (thalamus) -> primary auditory cortex

dorsal root ganglia

A cluster of unipolar sensory neuron cell bodies next to the dorsal root, their axons extend into somatosensory nerve endings throughout the body

beta fiber

A myelinated nerve fiber connected to the skin. Responds to non-noxious mechanical stimulus (e.g. a feather touching the skin)

delta fiber

A myelinated nerve fiber connected to the skin. Responds to noxious mechanical stimulus (e.g. a hammer hitting your finger)

C fiber

An unmyelinated nerve fiber connected to the skin. Responds to noxious heat and chemical stimulus

nociceptors

Free nerve endings which capture pain and temperature stimuli. Found throughout the body (e.g., skin, muscles, internal organs, etc.)

substance P

A neurotransmitter involved in prolonged pain perception (e.g., tissue damage). Acts on mast cells which release histamine

dorsal-column medial-lemniscus pathway

The somatosensory pathway that carries touch information. The contralateral crossover happens at the dorsal column nuclei

anterolateral pathway

The somatosensory pathway that carries pain and temperature information. The contralateral crossover happens at the dorsal horn of the spinal cord.

Along the way, pain information is provided to various brainstem sites, which trigger pain associated behaviors/reflexes

somatotopically

In the primary somatosensory cortex, neurons are _______ organized, i.e., organized analogously to regions of the body

olfactory receptor cells

Bipolar neurons embedded in the olfactory epithelium (a thin sheet of cells lining the nasal cavity). One dendritic process with several membrane extensions called olfactory cilia, which capture odorant molecules

odor map

The pattern of activation in the olfactory system in which odorants with different properties create a "map" of activation based on these properties, allowing us to distinguish way more than 350 types of smells (the different types of OR genes in humans).

olfactory glomerulus

A bundle of dendrites of mitral cells (main output cells of the olfactory bulb - bypass the thalamus). About 2000 exist in the olfactory bulb.

Note: Cells expressing the same OR gene converge onto the same bundle.

papillae

Small bulges which cover the surface of the tongue, each containing several hundred taste buds (which are a cluster of ~100 taste receptor cells)

taste pore

An opening in the taste receptor cell, a cluster of thin membrane extensions called microvilli

james-lange theory

A theory of emotional processing with a linear order of events: see emotional stimuli -> bodily response -> feel fear

i.e., your consciousness has a slower response time and is reacting to physiological changes within your body

cannon-bard theory

A theory of emotional processing involving parallel processes. see emotional stimuli -> feel fear and see emotional stimuli -> bodily response.

i.e., the mental and physical processing happens simultaneously

medial geniculate nucleus

A sub region of the thalamus vital for acquiring new conditioned fears.

Lesions to this region prevents the fear conditioning process.

Note: Lesioning the auditory cortex does not prevent fear conditioning. It is a process which does not require conscious perception

amygdala

A limbic system structure involved in learning and emotion, particularly fear and aggression.

Also involved in retaining the emotional significance of the sensory input

lateral nucleus (LA)

A part of the amygdalae complex, receives sensory, PFC, and HC input

Important for acquisition, storage, and expression of conditioned fear

central nucleus (CE)

A part of the amygdalae complex, controls defensive behavior by projection output to other relevant regions (e.g. hypothalamus & brainstem).

Links the amygdala to ANS, hormones, and behavior

hippocampus

A neural center located in the limbic system that helps process explicit memories for storage.

Specifically involved in contextual fear conditioning

hypothalamic-pituitary-adrenal (HPA) axis

A sequence of activity that occurs as a response to stress. Starts at the hypothalamus (specifically, the PVN), which triggers the pituitary gland (releasing adreno-cortico-hormone (ACTH)), which triggers the adrenal glands (specifically the adrenal cortex), which releases gluco-corticoids (e.g. cortisol) into the bloodstream.

gluco-corticoids

Hormones (e.g. cortisol) which lead to energy mobilization (in the form of increased blood-glucose availability) during the stress response.

Has a negative feedback effect which suppresses ACTH production (helps maintain homeostasis)

SNS stress response

A sequence of stress activity that occurs as a response to stress. The hypothalamus sends a signal to the brain stem, which sends a signal to the adrenal medulla. The adrenal medulla releases epinephrine (aka adrenaline) and norepinephrine.

These hormones produce a physiological stress response.

nodes of ranvier

Gaps in the myelin sheath to which voltage-gated sodium channels are confined.

axon hillock

The cone-shaped area on the cell body from which the axon originates

absolute refractory period

A period of time where it is impossible for another action potential to be produced. During the rising period of the spike

relative refractory period

A period where only strong stimulation can produce another action potential. During the falling period of the spike and the following hyperpolarization

sodium-potassium pump

An ion pump that pushed Na+ OUT of the neuron and pulls K+ IN to the neuron.

3 Na+ is exchanged for 2 K+

Responsible for creating the ion concentration gradient

leaky K channels

The movement of K+ ions through these channels is the main driving force behind resting potential generation.

There are more K+ ions inside the cell than outside, equilibrium potential is a result of the competition between two forces: concentration gradient (pulling out) and electrostatic pressure (pulling in).

concentration gradient (diffusion)

The force that causes ions to flow from areas of high to low concentration

electrostatic pressure

The force the causes ions to flow towards oppositely charges areas

outside inside

Na+ and Cl - have a higher concentration on the __________ of the neuron than the _________.
(separate with spaces)

inside outside

K+ and A- have a higher concentration on the __________ of the neuron than the _________.
(separate with spaces)

exocytosis

A process by which the NT's within a neuron's vacuole are released to the synaptic cleft through fusion of the vacuole membrane with the neural membrane.

Triggered by the influx of Ca2+ into the axon terminal.

acetylcholine (ACh)

The only neurotransmitter used in the motor division of the somatic nervous system

glutamate

A major excitatory neurotransmitter in the brain

GABA

A major inhibitory neurotransmitter in the brain

ionotropic receptors

Receptors that are coupled to ion channels and affect the neuron by causing those channels to open.

The receptor itself is essentially an ion channel. They are fast acting and the effects are short-lived

metabotropic receptors

Receptors that control ion channels indirectly through G protein complexes.

They are slow acting and produce long lasting activity

heteroreceptors

Receptors located in postsynaptic neurons

autoreceptors

Receptors located in presynaptic neurons, specifically in axon terminals.

Can be of the presynaptic (in axon terminal) or somatodendritic (in dendrite) variety.

They function in a negative regulatory feedback loop. E.g., if too much NT is released then some of that NT binds to the receptor and slows release.

dorsal horn

A region at the rear of the spinal cord that receives inputs from sensory receptors

ventral horn

A region of the spinal cord that contains efferent nuclei, particularly those related to motor control

neuromuscular junction

The point of contact between a motor neuron and a skeletal muscle cell.
Motor neurons release ACh, which causes muscle muscle contractions

myofiber (muscle fiber)

A single, very long cell with multiple nuclei. Composed of multiple cylinder-shaped protein bundles called myofibrils.

myofibril

Each of these bundles is made of a repeating functional unit called a sarcomere.

A tightly packed cylinder-shaped bundle of protein, multiple of which compose a myofiber.

sarcomere

A contractile functional unit of a myofibril. Contains a thick filament (myosin - pulls) and a thin filament (actin - is pulled)

tropomyosin complex

Threads which mask actin filaments, preventing myosin from gabbing on.

ACh causes the release of Ca2+, which binds to receptors on this complex called troponin, causing the threads to be pulled aside, exposing myosin binding sites

muscle spindle

A specialized muscle fiber which reports muscle length, composed of mechanosensory axon terminals.

A sudden stretch of this fiber causes a muscle stretch reflex

golgi-tendon reflex

A reflex which disengages muscle activity as a protective measure. Triggered by mechanosensory receptors after a tension threshold is reach in the golgi-tendon organ.

This organ is located at the junction between muscle and bone.

secondary motor cortex

The cortical region responsible for planning a sequence of movements to perform. Becomes active right before the initiation of a voluntary movement. Sends its output to the primary motor cortex through the basal-ganglia thalamic circuit

primary motor cortex

Executes motor commands by innervating motor neurons in the spinal cord.

Disproportionately larger areas are devoted to body parts that require complex movements (e.g. hands have more area than the trunk).

dorsolateral pathways

The motor pathways from the cortex to distal muscles (arms, legs, hands, fingers, toes).

Includes two sub pathways: The corticospinal tract and the corticorubrospinal tract

corticospinal tract (dorsolateral)

One of the dorsolateral motor pathways, controlling the wrist, hands, fingers, and toes.

Neurons in the primary motor cortex directly synapse onto neurons in the spinal cord.

Axons descend through the medullary pyramids (brainstem), which is where the midline crossing occurs.

corticorubrospinal tract (dorsolateral)

One of the dorsolateral motor pathways, controlling the arms, legs, and facial muscles.

Neurons in the primary motor cortex synapse onto the red nucleus, crossing the midline at the level of the medulla. Some axons synapse on motor neurons in the brainstem that control facial muscles

ventromedial pathways

The motor pathways from the cortex to proximal muscles (muscles in trunk and proximal limbs).

Consists of two sub pathways: The corticospinal tract and the cortico-brainstem-spinal tract

corticospinal tract (ventromedial)

One of the ventromedial motor pathways, controlling the trunk and proximal limbs for goal-directed movements.

Descends ipsilaterally, upon reaching the spinal cord, starts branching bilaterally in multiple spinal segments.

cortico-brainstem-spinal tract (ventromedial)

One of the ventromedial motor pathways, controlling the trunk and proximal limbs for posture adjustments in response to sensory signals (vestibular, auditory, visual)

Synapses in various brainstem structures, which innervate multiple spinal segments.

A passive response system

basal ganglia-thalamic circuit

The secondary motor cortex (planning) sends signals to the primary motor cortex (execution) through this circuit. This 'middleman' pathway serves to refine movement commands to be more smooth and streamlined. Without it, movement is severely limited.

Moves through structures of the basal ganglia, such as the striatum, globus pallidus (Interna Gp-i and Externa Gp-e), and the substantia niagra.

globus pallidus

Component of the basal ganglia that connects to the thalamus which relays information to the primary motor cortex.

Composed of the Interna (Gp-i) and Externa (Gp-e).

interna (Gp-i)

A component of the globus pallidus (basal ganglia). When at rest, this area is continuously firing APs, causing a constant release of GABA chemicals at the thalamus, causing inhibition. Think of it as a 'parking brake'

When this component itself is inhibited by the striatum, then the Thalamus is allowed to fire (disinhibition; D1 Pathway). This pathway is activated when the striatum's D1R receptors are active.

externa (Gp-e)

A component of the globus pallidus (basal ganglia). An important part of the deactivation pathway (D2 pathway), when the straitum inhibits this component from sending GABA to the gp-i, the gp-i is then able to inhibit the Thalamus, thus preventing movement.

This pathway is activated when the striatum's D2R receptors fire.

striatum

A component of the basal ganglia which initiates a particular movement pathway within the basal-ganglia thalamic circuit.

When the substantia nigra (also part of the basal ganglia) releases dopamine which binds to the component's receptors D1R cells (go pathway) they are activated and D2R cells (no-go) are inhibited.

Note: This means dopamine signals promote movement. Lack of dopamine makes movement impossible.

Cephalic (head) and digestive phase

One of the three phases of energy metabolism. Begins with sensory detection of food (e.g., smell, sight) followed by food intake and digestion.

During the digestive phase, foods are broken down into 3 types of molecules:

Glucose (from carbohydrates),

Amino acids (from proteins),

Fatty acids (from fats)

Absorptive phase

One of the three phases of energy metabolism. Nutrients are absorbed into the bloodstream. Some nutrients are consumed to meet immediate energy needs, others are stored long term.

Excess nutrients are stored as glycogen, proteins, and fats.

For short term storage: glucose is converted to glycogen

For long term storage: glucose and fatty acids are converted to fat (lipids).