Chapter 12 Flashcards
four regions that respond to both types (social/ physical) pain
insula, dorsal anterior cingulate (limbic) cortex, somatosensory thalamus, and secondary somatosensory cortex
emotion
cognitive interpretation of subjective feelings.
motivation
Behavior that seems purposeful and goal-directed.
sensory deprivation
experimental setup in which a subject is allowed only restricted sensory input; subjects generally have a low tolerance for deprivation and may even display hallucinations.
androgen
Male hormone related to level of sexual interest.
what is one way to modulate reward circuits?
chemical senses: smell & taste
chemosignals (chemical signals)
play a central role in motivated and emotional behavior
role of olfaction
seems designed to discriminate whether information is safe or familiar
what does scent interact with?
chemical receptors
Are chemical receptors replaced?
chemical receptors are constantly being replaced
how long to olfactory receptors last?
60 days
olfactory epithelium
The receptor surface for olfaction; lies in the nasal cavity,
what is the olfactory epithelium made of?
composed of receptor cells and support cells
what do olfactory epithelium receptor cells do?
sends a process that ends in 10 to 20 cilia into a mucous layer
name of the mucous layer?
olfactory mucosa.
what happens if receptors are affected by an olfactory chemosignal?
metabotropic activation of a specific G protein leads to an opening of sodium channels and a change in membrane potential.
What do olfactory receptor neurons in vertebrates respond to?
do not respond to specific odors but rather to a range of odors
What produces our perception of a particular odor?
any given odorant stimulates a unique pattern of receptors, and the summed activity, or pattern of activity
where do olfactory receptor cells project?
to the olfactory bulb, ending in ball-like tufts of dendrites called glomeruli
what do olfactory receptor cells form synapses with?
dendrites of mitral cells
where do mitral cells send their axons?
send their axons from the olfactory bulb to the broad range of forebrain areas
orbitofrontal cortex (oFc)
prefrontal cortex located behind the eye sockets (the orbits) that receives projections from the dorsomedial nucleus of the thalamus; plays a central role in a variety of emotional and social behaviors as well as in eating; also called orbital frontal cortex.
pheromone
odorant biochemical released by one animal that acts as a chemosignal and can affect the physiology or behavior of another animal.
vomeronasal organ
detects pheromones; made up of a small group of sensory receptors connected by a duct to the nasal passage.
what does the vomeronasal organ connect with?
primarily with the amygdala and hypothalamus by which it probably plays a role in reproductive and social behavior.
Are common odors and body odors analyzed the same?
no
do both common odors and body odors activate the primary olfactory regions?
yes
What other regions do body odors activate?
posterior cingulate cortex, occipital cortex, and anterior cingulate cortex (emotional stimuli)
what regions are activated by a stranger’s odor?
the amygdala and insular cortex, similar to activation observed for fearful visual stimuli
Why are some people sensitive to bitterness?
The sensitivity to bitterness is related to genetic differences in the ability to detect a specific bitter chemical (6-n-propylthiouracil, or PROP). PROP bitterness associates with allelic variation in the taste receptor gene, TAS2R38
What determines bitterness?
bitterness is related both to TAS2R38 and to tongue anatomy.
Do we have the same # of taste receptors throughout life?
By age 20, humans have lost at least an estimated 50 percent of their taste receptor
where are taste receptors located?
within taste buds located on the tongue, under the tongue, on the soft palate on the roof of the mouth, on the sides of the mouth, and at the back of the mouth on the nasopharnyx.
five most taste-receptor types
umami, sweet, sour, salty, and bitter
what is umami receptor sensitive to?
glutamate, a neurotransmitter molecule, and perhaps to protein.
microvilli
receptor tips
How do we taste?
Gustatory stimuli interact with the receptor tips, the micro- villi, to open ion channels, leading to changes in membrane potential. The base of the taste bud is contacted by the branches of afferent nerves that come from cranial nerves 7 (facial nerve), 9 (glossopharyngeal nerve), or 10 (vagus nerve).
cranial nerve 7
facial nerve
cranial nerve 9
glossopharyngeal nerve
cranial nerve 10
vagus nerve
solitary tract
the main gustatory nerve, formed by cranial nerves 7, 9, and 10
how many gustatory pathways are there?
2
Gustatory Pathway 1
through posterior medulla–> ventroposterior medial nucleus of the thalamus–> splits into 2 pathways–> primary somatosensory cortex & gustatory cortex of the insula
gustatory region of insula
dedicated to taste (identifies nature and intensity of flavor); sends a projection to the orbital cortex in a region near the input from the olfactory cortex. It is likely that the mixture of olfactory and gustatory input in the orbital cortex gives rise to our perception of flavor.
primary somatosensory region
also responsive to tactile information and is probably responsible for localizing tastes on the tongue and for our reactions to a food’s texture
orbital frontal cortec
evaluates the affective properties of tastes.
Innate releasing mechanism (iRM)
hypothetical mechanism that detects specific sensory stimuli and directs an organism to take a particular action.
evolutionary psychology
Discipline that seeks to apply principles of natural selection to understand the causes of human behavior.
what is the purpose of IRMs?
activators for inborn, adaptive responses that aid an animal’s survival. IRMs help an animal to successfully feed, reproduce, and escape predators.
Are IRMs prewired?
are prewired into the brain, but they can be modified by ex- perience.
reinforcer
in operant conditioning, any event that strengthens the behavior it follows.
learned taste aversion
acquired association between a specific taste or odor and illness; leads to an aversion to foods that have the taste or odor.
preparedness
Predisposition to respond to certain stimuli differently from other stimuli.
critical neural structures in emotional and motivated behavior
hypothalamus and associated pituitary gland, the limbic system, and the frontal lobes
where do the limbic and frontal regions project?
hypothalamus
what does the hypothalamus do?
which houses many basic neural circuits for controlling behavior and for autonomic processes that maintain homeostatic mechanisms
homeostatic mechanism
Process that maintains critical body functions within a narrow, fixed range.
regulatory behavior
Behavior motivated to meet the survival needs of the animal.
what controls regulatory behavior?
homeostatic mechanisms
setpoint
a “thermostat” in the hypothalamus that holds internal temperature at about 37 degrees Celsius
is the hypothalamus involved in all the body’s homeostatic systems?
yes
nonregulatory behavior
Behavior unnecessary to the basic survival needs of the animal.
pituitary gland
endocrine gland attached
to the bottom of the hypothalamus; its secretions control the activities of many other endocrine glands; known to be associated with biological rhythms.
medial forebrain bundle (MFB)
tract that connects structures in the brainstem with various parts of the limbic system; forms the activating projections that run from the brainstem to the basal ganglia and frontal cortex.
what are nonregulatory behaviors influenced by?
external stimuli. As a result, sensory systems must play some role in controlling them
how does the hypothalamus maintain homeostasis?
by acting on both the endocrine system and the autonomic nervous system (ANS) to regulate our internal environment.
what is a principle function of the hypothalamus?
to control the pituitary gland
three regions of the hypothalamus
lateral, medial, and periventricular
what forms a significant part of the medial forebrain bundle?
Fibers that ascend from the dopamine and noradrenaline-containing cells of the lower brainstem
dopamine-containing fibers of the MFB
contribute to the control of many motivated behaviors, including eating and sex. They also contribute to pathological behaviors, such as addiction and impulsivity.
hypothalamic nucleus
each is anatomically distinct, but most have multiple functions, in part because the cells in different nuclei contain various peptide neurotransmitters. Each peptide plays a role in different behaviors.
how many glads does the pituitary have?
2; anterior and posterior glands
posterior pituitary gland
composed of neural tissue and is essentially a continuation of the hypothalamus.
How the hypothalamus exerts effects
Neurons in the hypothalamus make peptides (e.g., oxytocin and vasopressin) that are transported down their axons to terminals lying in the posterior pituitary. But rather than affecting another neuron, as occurs at most synapses, these peptides are picked up by capillaries (tiny blood vessels) in the posterior pituitary’s rich vascular bed. The peptides then enter the body’s bloodstream. The blood carries them to distant targets, where they exert their effects
anterior pituitary gland
synthesizes various hormones.
releasing hormones
Peptides that are released by the hypothalamus and act to increase or decrease the release of hormones from the anterior pituitary.
Three factors that control hypothalamic hormone-related activity:
feedback loops, neural regulation, and responses based on experience.
adrenocorticotrophic hormone (acth)
controls secretions of the adrenal cortex


thyroid-stimulating hormone (tsh)
controls secretions of the thyroid gland
follicle-stimulating hormone (fsh)
controls secretions of the gonads
luteinizing hormone (lh)
controls secretions of the gonads
Prolactin
controls secretions of the mammary glands
growth hormone (gh)
Promotes growth throughout the body
Feedback Loops
When the level of, say, thyroid hormone is low, the hypothalamus releases thyroid-stimulating hormone–releasing hormone (TSH–releasing hormone) that stimulates the anterior pituitary to release TSH. TSH then acts on the thyroid gland to secrete more thyroid hormone. There must be some control over how much hormone is secreted, and the hypo- thalamus has receptors to detect the level of thyroid hormone. When that level rises, the hypothalamus lessens its secretion of TSH–releasing hormone.
neural control
requires regulation by other brain structures, such as the limbic system and the frontal lobes
function of oxytocin
stimulate cells of the mammary glands to release milk.
experiential responses
In response to experience, neurons in the hypothalamus undergo structural and biochemical changes just as cells in other brain regions do
Besides controlling hormone systems, what does the hypothalamus do?
generate behavior
what makes up the limbic cortex?
the cingulate gyrus & the hippocampal formation
what makes up the hippocampal formation?
hippocampus and the parahippocampal cortex
hippocampus
distinctive, three-layered subcortical structure of the limbic system lying in the medial region of the temporal lobe; plays a role in species-specific behaviors, memory, and spatial navigation and is vulnerable to the effects of stress; named for the greek word for seahorse.
Papez circuit
Papez concluded from his observations that the limbic lobe and associated subcortical structures provide the neural basis of emotion. This circuit is how he thought emotion could reach consciousness (cerebral cortex)
limbic circuit
The hippocampus, amygdala, and prefrontal cortex all connect with the hypothalamus. The mammillary nucleus of the hypothalamus connects to the anterior thalamus, which in turn connects with the cingulate cortex that then completes the circuit by connecting with the hippocampal formation, amygdala, and prefrontal cortex.
Three subdivisions of the amygdala
the corticomedial area, the basolateral area, and the central area.
where does the amygdala receive input from?
all sensory systems; needs complex stimuli to be excited
are amygdala neurons multimodal?
yes
multimodal
they respond to more than one sensory modality
where does the amygdala send output?
primarily to the hypothalamus and the brainstem, where it influences neural activity associated with emotions and species-typical behavior.
amygdala
almond-shaped collection of nuclei located within the limbic system; plays a role in emotional and species-typical behaviors.
prefrontal cortex (PFc)
the large frontal- lobe area anterior to the motor and premotor cortex; plays a key role in controlling executive functions such as planning.
motor cortex
controls fine movements, especially of the fingers, hands, toes, feet, tongue, and face.
The premotor cortex
participates in the selection of appropriate movement sequences.
4 areas of the prefrontal cortex
dorsolateral region; the orbitofrontal cortex, the ventromedial PFC; and the anterior cingulate cortex (ACC)
prefrontal cortex and Movement
plays a role in specifying the goals toward which movement should be directed. It controls the processes by which we select movements that are ap- propriate for the particular time and context. This selection may be cued by internal information (such as memory and emotion) or it may be made in response to context (environmental information).
Are neurons in the prefrontal cortex multimodal?
yes
where does the prefrontal cortex receive connections?
the amygdala, the dorsomedial thalamus, the sensory association cortex, the posterior parietal cortex, and the dopaminergic cells of the ventral tegmental area.
What role does the dopaminergic input play in prefrontal neurons?
regulating how prefrontal neurons react to stimuli, including emotional ones.
Role of prefrontal cortex in behavior?
selecting behaviors appropriate to the particular time and place.
dorsolateral frontal lobe damage
become overly dependent on environmental cues to determine their behavior; easily distracted by what they see or hear
what are the size of the frontal lobes related to?
a species’ sociability
agenesis of the frontal lobes
failure of frontal lobes to develop
somatic marker hypothesis
Posits that “marker” signals arising from emotions and feelings act to guide behavior and decision making, usually in an unconscious process.
Klüver-Bucy syndrome
Behavioral syndrome, characterized especially by hypersexuality, that results from bilateral injury to the temporal lobe.
three forms of emotional experience
autonomic, emotional, thoughts
autonomic emotional experience
hypothalamus and associated structures
feelings of emotional experience
amygdala and part of frontal lobes
thoughts of emotional experience
cortex
James-Lange theory
the brain concocts a story to explain bodily reactions
Damasio’s somatic marker hypothesis
proposed that emotions are responses induced by either internal or external stimuli not normally attended to consciously.
what is removed in Kluver-Bucy syndrome?
amygdala
Awareness of danger and of safety
has both an innate and a learned component,
innate component of awareness of danger and of safety
is the automatic processing of species-relevant sensory information—in- puts from the visual, auditory, and olfactory systems
learned component of fear and of safety
consists of the avoidance of specific ani- mals, places, and objects that the organism has come to associate with danger
psychosurgery
any neurosurgical technique intended to alter behavior.
damage to orbital region
can produce severe personality change characterized by apathy and loss of initiative or drive.
what does the orbital cortex do?
probably responsible for the conscious awareness of emotional states produced by the rest of the limbic system, especially the amygdala.
mechanism for raising anxiety
seems to entail a compound known as diazepam-binding inhibitor that appears to bind antago- nistically with the GABAA receptor, resulting in greater anxiety.
generalized anxiety disorder
Persistently high levels of anxiety often accompanied by maladaptive behaviors to reduce anxiety; the disorder is thought to be caused by chronic stress.
phobia
fear of a clearly defined object or situation.
panic disorder
recurrent attacks of intense terror that come on without warning and without any apparent relation to external circumstances.
regulatory behaviors
maintain vital body-system balance or homeostasis,
nonregulatory behaviors
behaviors not controlled by a homeostatic mechanism
obesity
excessive accumulation of body fat.
anorexia nervosa
exaggerated concern with being overweight that leads to inadequate food intake and often excessive exercising; can lead to severe weight loss and even starvation.
inputs to the human control system for feeding come from three major sources:
cognitive factors, hypothalamus, digestive system
aphagia
failure to eat; may be due to an unwillingness to eat or to motor difficulties, especially with swallowing; damage to lateral hypothalamus
hyperphagia
disorder in which an animal overeats, leading to significant weight gain; damage to ventromedial hypothalamus
what does the digestive system extract?
three types of nutrients: lipids (fats), amino acids (the building blocks of proteins), and glucose (sugar)
glucose
body’s primary fuel and is virtually the only energy source for the brain
glucose and the liver
Because the brain requires glucose even when the digestive tract is empty, the liver acts as a short-term reservoir of glycogen, a starch that acts as an inert form of glucose. When blood-sugar levels fall, as when we are sleeping, detector cells tell the liver to release glucose by converting glycogen into glucose.
food in the intestines
When food reaches the intestines, it interacts with receptors there to trigger the release of at least 10 different peptide hormones, including one known as cholecystokinin (CCK).
what does the level of CCK play a role in?
satiety
satiety
the feeling of having eaten enough.
what is the key structure in feeding?
hypothalamus
what influences feeding behavior?
hormones, including insulin, growth hormone, and sex steroids that stimulate and inhibit feeding and aid in converting nutrients into fat and fat into glucose.
damage to the lateral and ventromedial hypothalamus and to the paraventricular nucleus
changes in hormone levels (especially insulin), in sensory reactivity (the taste and attractiveness of food is altered), in glucose and lipid levels in the blood, and in metabolic rate.
The general role of the hypothalamus
act as a sensor for the levels of lipids, glucose, hormones, and various pep- tides.
where does the homeostat receive input?
the digestive system (such as information about blood-glucose levels), hormone systems (such as information about the level of CCK), and parts of the brain that pro- cess cognitive factors.
damage to amygdala
alters food preferences and abolishes taste-aversion
learning.
damage to the orbital prefrontal cortex
decreases eating because of diminished sensory responses to food odor and perhaps to taste.
osmotic thirst
thirst that results from an increased concentration of dissolved chemicals, or solutes, in body fluids.
hypovolumic thirst
thirst that is produced by a loss of overall fluid volume from the body.
hypothalamus and osmotic thirst
Receptors in the hypothalamus along the third ventricle detect the altered solute concentration and relay the message “too salty” to various hypothalamic areas that, in turn, stimulate us to drink. Other messages are sent to the kidneys to reduce water excretion.
water intoxication
kidneys cannot keep up with ingestion of large amounts of water
is sex a regulatory behavior?
no
where in the brain do gonadal hormones have organizing effects?
hypothalamus, especially the preoptic area of the medial hypothalamus. Organizing effects also operate in other nervous system regions, notably the amygdala, the prefrontal cortex, and the spinal cord.
activating effects
actions of hormones on the adult brain
organizing effects
actions of hormones on the developing brain
sexual dimorphism
differential development of brain areas in the two sexes.
steps of sexual dimorphism
Cells in the brain produce aromatase, an enzyme that converts testosterone into estradiol, one of the class of female sex hormones called estrogens. Thus, when males produce testosterone, it gets converted in the brain into an estrogen. Therefore a female hormone, estradiol, actually masculinizes a male brain. Females are not masculinized by the presence of estrogens because the fetuses of both sexes produce a liver enzyme (alpha fetoprotein) that binds to estrogen, rendering it incapable of entering neurons. Testosterone is unaffected by alpha fetoprotein, so it enters neurons and is converted into estradiol.
do gonadal hormones effect adult brains?
yes
2 ways testosterone activates sexual behavior
the actions of testosterone on the amygdala are related to the motivation to seek sexual activity. Second, the actions of testosterone on the hypothalamus are needed to produce copulatory behavior.
lordosis
controlled by the ventromedial hypothalamus; arching the back and el- evating the rump while the female otherwise remains quite still
what does the medial preoptic area control in males?
copulation–but it does not control motivation
Hypothalamus & sex
controls copulatory behavior in both male and female mammals
amygdala & sex
influences sexual motivation, and it prob- ably plays a key role in female sexual motivation as well, especially among females of species, such as humans, in which sexual activity is not tied to fluctuations in ovarian hormones.
sexual orientation
a person’s sexual attraction to the opposite sex or to the same sex or to both sexes.
gender identity
a person’s feeling of being either male or female.
transsexuality
gender-identity disorder involving the strong belief of having been born the wrong sex.
what causes sex differences in the hypothalamus?
gene methylation
regions involved in brain-stimulation reward
lateral hypothalamus and medial forebrain bundle
what does stimulation of the medical forebrain bundle activate?
fibers that form the ascending pathways from dopamine-producing cells of the midbrain tegmentum
what does the mesolimbic dopamine pathway send terminals?
various sites, including especially the nucleus accumbens in the basal ganglia and the prefrontal cortex.
Why is the mesolimbic pathway central to circuits mediating reward?
- Dopamine release shows a marked increase when animals are engaged in intracranial self-stimulation.
- Drugs that enhance dopamine release increase self-stimulation, whereas drugs that decrease dopamine release decrease self-stimulation. It seems that the amount of dopamine released somehow determines how rewarding an event is.
- When animals engage in behaviors such as feeding or sexual activity, dopamine re- lease rapidly increases in locations such as the nucleus accumbens.
- Highly addictive drugs such as nicotine and cocaine increase the level of dopamine in the nucleus accumbens.
Liking
entails opioid and benzodiazepine–GABA systems.
reward pathways
are diffuse and that the size and activity of these pathways are related to the intensity of reward
