Bio-Psych Quiz 6

The REM Flip-Flop

1. A region in the dorsal pons contains REM-ON neurons. 2. A region in the dorsal midbrain contains REM-OFF neurons. 3. REM-ON and REM-OFF regions are interconnected by inhibitory GABA neurons. 4.Only one region can be active at any given time. If only one region, REM-ON or REM-OFF, can be active at any one time, then: 1. During waking, the REM-OFF region receives excitatory input from orexinergic neurons and tips the flip-flop to the REM-OFF (activating NE and 5-HT) 2. Once sleep begins, the activity of orexinergic neurons ceases, which removes the excitatory input to the REM-OFF region 3. As sleep progresses, NE and 5-HT neurons gradually decreases and REM flip-flop tips to the REM-ON Note: As sleep progresses, NE from locus coeruleus (promotes wakefulness) and 5-HT from raphé nuclei neurons (maintains NREM) gradually decreases and REM flip-flop tips to the REM-ON.

Electroencephalography Correlates of Behavioral State

1. Awake state, cortical EEG recorded from occipital area: beta rhythm - alert (beta is indicative of mental activity) alpha rhythm during relaxation 2. EEG shows cyclical changes during sleep. 3. At start of sleep, low voltage high frequency with bursts of theta activity.

Caffeine and Adenosine Receptors

1. Caffeine blocks adenosine receptors 2. Increased glutamate release follows 3. Increased arousal and alertness

Three Phases of Energy Metabolism

1. Cephalic phase: preparatory phase where sight, smell, and thought anticipate a meal and feeding is initiated 2. Absorptive phase: the period when energy from a meal is absorbed into the blood stream meeting the body's immediate energy needs 3. Fasting phase: the period when all the energy from the meal has been used and the body is using stored energy from previous meals

Suprachiasmatic Nuclei: Master Pacemaker

1. Lesions of SCN abolish free-running rhythms 2. Activity in SCN correlates with circadian rhythms 3. Isolated SCN continues to cycle 4. Transplanted SCN imparts rhythm of the donor 5. Pacemaker cells (cellular clock)

Control of NREM Sleep

1. The basal forebrain initiates NREM sleep 2. The caudal reticular formation initiates REM sleep 3. Basal forebrain region initiates NREM sleep. The raphé nuclei maintains NREM sleep. 4. Serotonin is the predominate neurotransmitter in the raphé nuclei

Types of Biological Rhythms

1. Ultradian (basic rest-activity Cycle) The regular recurrence in cycles of less than 24 hours 2. Circadian (daily sleep-wake cycles) 24-hour cycle 3. Infradian (menstrual cycle) 4. Circannual (annual breeding cycles) All rhythms allow us to anticipate change!

sleep spindle

12 to 14 Hz brain waves in bursts that last aat least half a second

Circadian rhythm

A daily rhythmical change in behavior or physiological process

zeitgeber

A stimulus that resets the circadian rhythm Light is the dominant zeitgeber for land animals Although circadian rhythms persist without light, light is critical for resetting them.

Adenosine

Adenosine, a nucleotide neuromodulator, has been suggested to play a primary role in the control of sleep. Prolonged wakefulness causes increased accumulation of adenosine that produces drowsiness and sleep.

Parameters used to describe Electroencephalography

Amplitude of signal - high vs low. Synchronization - desynchronization (cells firing at the same time are synchronized) Frequency of Dominant Rhythm Alpha 8-14 Slow Beta 15-30 fast Delta 1-5 Slowest Gamma 30-90 faster Theta 5-12 Slower

pineal gland

An endocrine gland located just posterior to the thalamus that releases the hormone melatonin

Cerveau isolé

Animals with only cerveau isolé transection show continous sleep (i.e., EEG is SWS) Bremer made a surgical transection between the superior colliculi and inferior colliculi (cerveau isolé) that isolated the forebrain. In this preparation the head and the brain are essentially isolated from the rest of the body. The forebrain (telencephalon and diencephalon) in front of the cut was intact as was the brain stem and rest of the nervous system behind the cut. Cats with cerveau isolé showed a constant state of sleep.

Encéphale Isolé

Animals with only encéphale isolé transection show normal sleep -wake cycles (i.e, EEG recordings) Bremer made a surgical transection that essentially isolated the head and the brain from the rest of the body. This is accomplished by a transection between the brain stem and the spinal cord called encéphale isolé. When he made the surgical transection just above the spinal cord (encéphale isolé), cats showed normal sleep-wake pattens. This preparation showed that neural mechanisms for sleep and waking did not require the spinal cord.

The Liver

Bile is produced in the liver and stored in the gall bladder. 1. Bile contains cholesterol, lecithin, and bile salts 2. Lecithin and bile salts normally keep cholesterol in solution 3. Cholesterol precipitation causes the formation of gall stones

Ventrolateral Preoptic Area

Damage to the ventrolateral preoptic area (VLPO) suppresses sleep. Activity of the VLPO increases during sleep Sleep neurons secrete GABA inhibiting lateral hypothalamic neurons that include: Acetylcholine Norepinephrine Serotonin Histamine Orexin

Deglutition

Deglutition (or swallowing) is the transport of material from mouth-to-stomach. There are two phases: 1. Oropharyngeal - conscious control of swallowing 2. Esophageal - involuntary control called "esophageal peristalsis" Upper and lower esophageal sphincters prevent reflux of food.

Electroencephalography

EEG Rhythms time vs voltage plots of electrical potential recorded from scalp electrodes. Genesis of EEG EEG rhythm reflect underlying neural activity in cortex. Origins of EEG are distant from electrode and can't be accurately localized with single electrode

Facilitated Diffusion

Facilitated diffusion is a passive transport mechanism in which carrier proteins shuttle molecules across the cell membrane without using the cell's energy supplies. Instead, the energy is provide by the concentration gradient, which means that molecules are transported from higher to lower concentrations, into or out of the cell. The carrier proteins bind to glucose, which causes them to change shape and translocate the glucose from one side of the membrane to the other. Red blood cells use facilitated diffusion to absorb glucose.

The Function of Dreaming

Facilitation of memory storage Reverse learning REM sleep functions to dispose of unwanted memories through a mechanism called reverse learning. Reverse learning operates during REM sleep to prevent the brain from being overloaded with massive amounts of information stored during wakefulness. Anatomical and functional brain maturation Catecholamine restoration Psychoanalytical (wish fulfillment or otherwise).

How Glucagon Works

Glucagon counterbalances the actions of insulin 4-6 hours after you eat, glucose levels in the bloodstream decrease, triggering your pancreas to release glucagon Glucagon signals the liver and muscle cells to convert stored glycogen back into glucose Glucose is raised in the bloodstream and begins the feedback loop of insulin-glucagon

Glucagon

Glucagon has the effect of increasing blood glucose. 1. It promotes the release of glucose from glycogen in the liver and muscles. 2. It promotes hepatic gluconeogenesis. Gluconeogenesis is the pathway by which non-hexose substrates such as amino acids are converted to glucose. Glucagon is often described as having the opposite effect of insulin. Glucagon is related to "release" and synthesis of glucose

electroencephalogram

In 1924, the first electroencephalogram recording was done by Hans Berger (1873-1941), an German psychiatrist.

Feeding Behavior

In simple models, constructs are often viewed together on one continuum. For example, Satiety Hunger

Digestion & Assimilation

Ingestion is the process of taking material (particularly food) into the gastrointestinal tract Digestion is the splitting of large chemical compounds in foods into smaller substances that the body can use Assimilation is the absorption of digestive end-products into body fluids and cells

Insulin

Insulin does three principle functions: 1. It promotes the use of glucose 2. It promotes the conversion of storage of glucose to glycogen and fat storage; and amino acids to protein synthesis 3. It promotes storage of glycogen in liver and muscle; fat storage to adipose tissue; protein storage to muscle Insulin is related to "storage" and immediate use of glucose.

Activation Synthesis Theory

John Allan Hobson and Robert McCarley (1977) proposed that dreaming results from the brain's attempt to make sense of neural activity that takes place during sleep. The activation-synthesis model suggests that dreams are caused by the physiological processes of the brain. The brain synthesizes and interprets this internal activity and attempts create meaning from these signals, which results in dreaming.

Suprachiasmatic Nuclei: Controls Pineal Gland Secretion of Melatonin

Light exposure to the retina is first relayed to the SCN The SCN via an inhibitory projection to the paraventricular nucleus (PVN), controls the sympathetic output to the pineal gland that is responsible for melatonin secretion. Fibers from the hypothalamus descend to the spinal cord and ultimately project to the superior cervical ganglia, from which post-ganglionic neurons ascend back to the pineal gland.

Cellular Clock:Circadian Photoreceptor

Melanopsin: A photopigment present in ganglion cells in the retina whose axons transmit information to the suprachiasmatic nuclei (SCN), the thalamus, and the olivary pretectal nucleus (in the midbrain). Intergeniculate leaflet (IGL): A part of the lateral geniculate nucleus (in the thalamus) that receives information from the retina and projects to the SCN; terminals release Neuropeptide Y at the SCN.

Moruzzi and Magoun

Moruzzi and Magoun showed that when the RAS is damaged, animals showed continuous sleep. When ascending sensory pathways are selectively lesioned, there is no disruption of sleep and wakefulness. This is evidence against Bremer's sensory stimulation hypothesis!

Orexin

Orexinergic neurons in the human brain project to almost every part of the brain, including the cerebral cortex and all of the regions involved in alertness and wakefulness, including the locus coeruleus, raphé nuclei, tuberomammillary nucleus, and acetylcholine neurons in the dorsal pons and basal forebrain. Orexin has an excitatory effect in all of these regions. Activation of orexin triggers wakefulness, while low levels of orexin at night serve to drive sleep

The Pancreas

Pancreatic juice contains electrolytes and digestive enzymes such as trypsinogen, the precursor to trypsin (acts on proteins), pancreatic lipase (acts on fats), and pancreatic amylase (acts on carbohydrate). The presence of chyme in the small intestine initiates a type of contraction called "segmentation" that moves the material to the large intestine.

pontomesencephalon

Part of the reticular formation that contributes to cortical arousal

Control of Seasonal Rhythms

Pineal gland: A gland attached to the dorsal tectum; produces melatonin and plays a role in circadian and seasonal rhythms. Melatonin: A hormone secreted during the night by the pineal body; plays a role in circadian and seasonal rhythms. Melatonin [derived from serotonin and is not an amine]

Reticular Formation (RAS) reticular activating system: RAS and Motor Function

RAS - Reticular Activating System Sends impulses to the cerebral cortex to keep it conscious and alert Filters out repetitive and weak stimuli Motor function RAS helps control coarse motor movements Autonomic centers regulate visceral motor functions - e.g., vasomotor, cardiac, and respiratory centers

melatonin

Released by the pineal gland, a hormone that influences both circadian and circannual rhythms The pineal gland secretes melatonin mostly at night, making us sleepy at that time. Secretion starts to increase about 2 or 3 hours before bedtime

Secondary Active Transport

Secondary active transport is another method by which cells import glucose. In this method, a transmembrane protein known as a symporter imports two sodium ions for every glucose molecule it imports. The method doesn't use ATP, but instead relies on the higher concentration gradient of sodium outside the cell relative to the cell interior. The positively charged sodium ions provide electrochemical energy to import glucose with or against the glucose concentration gradient. Secondary active transport is used by cells in the small intestine, heart, brain, kidneys and certain other organs.

Ventrolateral Preoptic Area(the so-called "sleep switch")

Sleep neurons secrete GABA inhibiting lateral hypothalamic neurons that include: Acetylcholine, Norepinephrine, Serotonin, Histamine, and Orexin In a process of "mutual inhibition" during waking hours, those areas of the brain that are active in maintaining wakefulness by stimulating the cerebral cortex also work to inhibit the neurons of the VLPO.

Stomach

Stomach has three functions: 1. Storage of a meal 2. Mixing of food with gastric secretions -pepsin, hydrochloric acid, mucin, some inorganic salts - usually referred to as "gastric juice' (pH 0.9 - 1.5) 3. Emptying of food from the stomach into the small intestine

Bremer concluded

That sleep is produced by the lack of sensory input to the cerebral cortex wakefulness results from sensory stimulation coming up from brain sensory systems Bremer's "sensory stimulation hypothesis" was WRONG! (Note: Bremer's view implies that sleep is the baseline state of the brain and requires arousal)

Preoptic area (POA).

The basal forebrain includes an anterior area of the hypothalamus called the preoptic area (POA). The POA has been shown to produce sleep in laboratory animals and damage to the POA causes sleeplessness People become sleepier in warmer weather and thermoreceptors in skin transmit temperature information to POA. Warming POA neurons in laboratory animals promotes NREM

Primary Active Transport

The cells along the small intestine use primary active transport to ensure that glucose only flows one way: from digested food to the inside of cells. Active transport proteins use adenosine triphosphate (ATP), the cell's energy storage molecule, to pump glucose into the cell, either with or against the concentration gradient.

How Insulin Works

The increase in glucose alerts the pancreas to release insulin into bloodstream Insulin alerts cells throughout the body to take in glucose from bloodstream Glucose moves into cells, and blood glucose levels lower Some cells use glucose as energy Other cells, liver and muscles, store excess glucose as glycogen

Control of REM Sleep: locus coeruleus

The locus coeruleus is associated with the absence of REM. REM sleep occurs when the locus coreuleus is not active Decreased locus coeruleus activity removes inhibition of the caudal reticular formation (i.e., REM increases) REM sleep is also associated with cholinergic brain stem mechanisms

suprachiasmatic nucleus (SCN)

The main driver of rhythms for sleep and body temperature Part of the hypothalamus; provides the main control of the circadian rhythms for sleep and body temperature The SCN works like a clock that sets off a regulated pattern of activities that affect the entire body. Once exposed to the first light each day, the clock in the SCN begins performing functions like raising body temperature and releasing stimulating hormones like cortisol. The SCN also delays the release of other hormones like melatonin, which is associated with sleep onset, until many hours later when darkness arrives. After damage to the SCN, the bodies rhythms become erratic. The SCN generates circadian rhythms itself in a genetically controlled manner.

Glucose and the Brain

The mammalian brain depends on glucose as its main source of energy. In the adult brain, neurons have the highest energy demand, requiring continuous delivery of glucose from blood. Glucose metabolism provides the fuel for physiological brain function through the generation of adenosine triphosphate (ATP) The tight junctions between endothelial cells are responsible for the blood-brain barrier function. Glucose from blood enters the brain by a transport protein. Glucose transport protein (GLUT-1) is highly enriched in brain capillary endothelial cells. These transporters carry glucose molecules through the blood-brain barrier (facilitated diffusion). Insulin is not needed for glucose transport into most brain cells.

Reticular Formation

The most important function of RAS is to regulate the shift between sleep and wakefulness. The transition made by our body from deep slumber to being completely awake It is also responsible for supplying integrated response to the outside stimuli.

Mastication

The process of digestion and assimilation in the human begins in the mouth where "mastication" begins: 1. Reduce particle size to facilitate the breakdown by enzymes 2. Mix with saliva (primary carbohydrate breakdown) 3. stimulate afferent receptors that trigger the cephalic phase of digestion 4. Form a bolus in preparation for deglutition (the act of swallowing) Additionally, mastication stimulates taste. The pleasant sensations of sight, smell, and taste and the chewing of food leads to parasympathetic activation of the salivary, gastric, and pancreatic secretion.

Small Intestine

The small intestine is where the majority of absorption occurs. The first 8-10 inches of small intestine is called the "duodenum". 1. Chyme empties into the duodenum and mixes with "bile" and pancreatic juice The next 8 ft is called the "jejunum". The next 12 ft is called the "ileum".

Neural Control of Arousal

There are at least five different neurotransmitters that play a role in arousal and wakefulness: 1. Aceteylcholine 2. Norepinephrine 3. Serotonin 4. Histamine 5. Orexin (a.k.a. hypocretin

biological clock

There is a projection that goes directly from the retina to the SCN providing it with information about light Light acts through blood-borne factors to reset the clock Melatonin can reset the biological clock: 1. Melatonin is secreted from the pineal gland 2. Increased levels of melatonin make you sleepy 3. Melatonin can act on receptors in the suprachiasmatic nuclei (SCN) to phase-advance the biological clock

Cephalic Reflexes

Triggered by taste and smell of food, cephalic reflexes include: The secretion of saliva in the mouth The secretion of gastric juices in the stomach The secretion of pancreatic enzymes in the small intestine The secretion of insulin into the blood stream

Neural Mechanisms of Sleep and Waking: locus coeruleus

Within the RAS is a group of neurons called the locus coeruleus that is important to alertness. The greater the activity of the locus coeruleus, then the higher the level of behavioral activity. The locus coeruleus is a NE system. Cognitive behaviors are mediated by a pathway from locus coeruleus to the prefrontal cortex.

polysomnograph

a combination of EEG and eye movement records

jet lag

a disruption of circadian rhythms due to crossing time zones

PGO waves

a distinctive pattern of high-amplitude electrical potentials that occur first in the pons, then in the lateral geniculate, and then in the occipital cortex

K-complex

a sharp brain wave associated with temporary inhibition of neural firing

locus coeruleus

a small structure in the pons that emits bursts of impulses in response to meaninful events, especially those that produce emotional arousal

alpha waves

a steady series of brain waves at a frequency of 8-12 per second that are characteristic of relaxation

reticular formation

a structure that extends from the medulla into the forebrain; controls motor areas of the spinal cord and selectively increases arousal and attention in various forebrain areas The reticular formation is the principal promoter for wakefulness

basal forebrain

area anterior and dorsal to the hypothalamus; includes cell clusters that promote wakefulness and sleep

vegetative state

condition in which someone has decreased brain activity and alternates between wakefulness and sleep but shows only limited responsiveness, such as increased heart rate in response to a painful stimulus

minimally concious state

condition of decreased brain activity with occasional, brief periods of purposeful actions and limited speech comprehension

brain death

condition with no sign of brain activity and no response to any stimulus

Gastric juice

has two principle secretions: 1. Hydrochloric acid and potassium 2. An alkaline secretion - sodium, postassium, chloride, bicarbonate, mucus, and digestive enzymes (e.g., pepsin) Gastric juice also contains some nonelectrolyte constituents - pepsinogen, intrinsic factor or the antianemic principle, and mucoproteins

activation-synthesis hypothesis

idea that a dream represents the brain's effort to make sense of sparse and distorted information

clinico-anatomical hypothesis

idea that considers dreams as a type of think that occurs under unusual conditions

Ingestive behavior

is composed of feeding behavior and drinking behavior. In feeding behavior, scientists have used terms related to motivational constructs, such as "hunger," "satiety," and "appetite." For example, 1. Hunger is the process that tends to activate feeding. 2. Satiety is the process that tends to stop feeding. 3. Appetite usually refers to feeding, in general.

orexin (hypocretin)

neurotransmitter that increases wakefulness and arousal

endogenous circadian rhythms

self-generated rhythm that lasts about a day

endogenous circannual rhythm

self-generated rhythm that lasts about a year

rapid eye movement (REM) sleep

sleep stage with rapid eye movements, high brain activity, and relaxation of the large muscles

paradoxical sleep

sleep that is deep in some ways and light in others

slow-wave sleep (SWS)

stages 3 and 4 of sleep, which are occupied by slow, large-amplitude brain waves

non-REM (NREM) sleep

stages of sleep other than REM