Brain Mind & Behavior Chapter 8
Hypothalamus Profile
Homeostasis ANS Endocrine System Body Temperature regulation Sex drive/sexual behavior Appetite and satiation (fullness) Thirst Biological Rhythms Sleep and Wakefulness Emotions Memory Immune Function
Thalamus Profile:
Relay distribution of most sensory and motor signals. Attention Consciousness Sleep Memory
Profile of the Diencephalon
Relay system between all sensory input (except smell) and other area's of the brain. Works closely with the limbic system (Emotions, Memory) Site for interaction between the brain and the ANS (Autonomic Nervous System) Site for interaction between the CNS and the endocrine system
The Thalamus and Attention
by selecting some input to relay to the Cortex, while filtering out, or ignoring most input the Thalamus is a key component in the brain's attention system. Input from the cerebral cortex signals the Thalamus to selectively attends to only to one specific types of sensory input.
Hypothalamus: Command Centers
consists of 23 Nuclei, each of which can be thought of a kind of "command center" for specific physiological activities. Regulates: thirst, temperature, sexual behavior, sleep & wake cycle, biological rhythms, oxytocin and vasopressin, regulation of hormone secretion, satiation (fullness), memory, SNS & ANS, blood pressure/heart rate, emotions, endocrine, stress. Regulates Pineal and pituitary glands.
The Thalamus
consists of two large egg-shaped structures found at the very center of the brain. It is the relaying and receiving station for all sensory information (except smell) and motor signals. Like a mail clerk, the ______ sorts through the sensory and motor information and relays it to the appropriate parts of the brain for further processing. Communication between the occipital lobe and the ________.
Hypothalamus and its needs detectors
constantly monitoring the body's internal state. When physiological needs or imbalances are detected the Hypothalamus triggers corrective measures to bring the body back to set point levels. i.e., temperature, thirst, hunger, sleep and sexual needs.
The Pulvinar (4 of 7)
is involved in integrating visual and auditory input and has output to the parietal lobes of the cerebral cortex.
the fullness detector
paraventricular nucleus (PVN) the Ventral-Medial hypothalamus (VMH) serve as the ______________ ________________.
(SDN) sexually dimorphic nucleus
part of the MPOA called the ___________is much larger in males of all mammals.
Neuropeptide Y (NPY)
(NPY) is a potent appetite stimulator produced in a part of the hypothalamus called the arcuate nucleus.
The Nuclei of the Thalamus (7 parts)
1. the medial geniculate nucleus (MG) 2. the lateral geniculate nucleus (LG) 3. Anterior Nucleus (AN) 4. the pulvinar 5. the ventral posterior lateral nuclei (VPL) 6. The ventral lateral (VL) and the ventral anterior nucleus (VA) 7. the mediodorsal nucleus (MN)
Hypothalamus and the regulation of body temperature
All physiological mechanisms involved in regulating body temperature are orchestrated by the hypothalamus. The anterior and preoptic nuclei
3 types of Endocrine hormones:
Amino acid derivatives (i.e., adrenaline), 2. peptides and proteins (i.e., insulin), and Steroids. (i.e., cortisol, testosterone, estrogen, progesterone).
Hypothalamus, Pituitary gland, and Endocrine System
An important way in which the hypothalamus works to maintain homeostasis is through its control of the endocrine system. This system consists of hormone secreting glands located in various parts of the body. These include the pineal gland (in the brain), thyroid and parathyroid (throat), adrenals (atop the kidneys), pancreas, thymus glands, the ovaries and testes, and endocrines cells that line the intestines.
Obestatin
Found by Stanford researchers, an appetite suppressing hormone called _________. Produced in the stomach and small intestine from the same precursor molecule as ghrelin.
Appetite Stimulating Chemicals
Ghrelin, Neuropeptide Y
PVS- Persistent Vegetative State
Large parts of the Cerebral cortex can be damaged or even removed without abolishing conscious awareness, but bilateral (both left and right thalamus) lesions to small areas within the thalamus may result in a condition called __________. In __________, the brain's energy consumption may drop to around one-third of normal levels- even lower than the levels recorded during deep sleep or general anesthesia. It is generally agreed that if this condition lasts more than six months to a year, depending on the cause, it is very likely to be permanent.
The Medial Geniculate Nucleus (MG) (1 of 7)
Latin for abruptly bent: is a relay station for auditory information. It receives auditory input from the inferior colliculus in the mid brain and relays it to the auditory cortex in the temporal lobe of the cortex.
Greek: Thin
Leptin
Obesity gene found in rats
Leptin gene found by Friedman (1994)
what can cure obesity in some patients?
Leptin injections.
Appetite Suppressing chemicals
Leptin, Peptide YY (PYY), obestatin
The Hypothalamus "The Needs Detector"
Literal term means "Lesser Thalamus" can hardly be the case in terms of behavior. It is closely interconnected to the brain stem, limbic system, cerebral cortex, the ANS, and the endocrine system. Only about the size of a pea, the 23 nuclei that make up the hypothalamus play pivotal roles in a wide range of behavior. Monitors the body's needs, maintenance of an internal equilibrium by adjusting its physiological processes.
The Diencephalon
Located just above the Brain Stem called the ____________. It interconnects with the brainstem, cerebellum, Limbic System, basal ganglia, cerebral cortex, endocrine system and the ANS (Autonomic Nervous System) Composed of two major structures: The Thalamus and the Hypothalamus.
Infradian Rhythms
Occur over periods longer than a day. some are weekly, monthly and annually.
Greek: Inner Chamber
Thalamus
The Brains Mail Clerk
Thalamus
Two Structures of the Diencephalon
Thalamus and Hypothalamus
Greek: Between Brains
The Diencephalon
The Thalamus and The doorway to consciousness
While conscious a constant flow of information between the thalamus and other parts of the brain generates a steady synchronous level of electrical activity oscillating at about 40 Hz. This activity only occurs while conscious and is not present during sleep or general anesthesia. Large parts of the Cerebral cortex can be damaged or even removed without abolishing conscious awareness, but bilateral (both left and right thalamus) lesions to small areas within the thalamus may result in a condition called PVS (persistent vegetative state).
The pineal gland
at sunset the SCN signals to the pineal gland (located deep in the interior of the brain, just above and behind the brainstem. to secrete melatonin in to the bloodstream.
Homeostatic regulation by the Hypothalamus
blood pressure body temperature body weight blood glucose appetite thirst sleep-wake energy levels hormone levels
Latin: circa and dia
circadian rhythm circa=around dia =day
Biological rhythms
circadian, ultradian, and infradian rhythms.
anterior and preoptic nuclei of the hypothalamus
continuously monitor the temperature of the body's blood supply. It will initiate a variety of heat regulating mechanisms- such as shivering or sweating. Though it is controlled through the ANS, they hypothalamus broadcasts signals throughout the body aimed at correcting body temperature.
Zeitbergers
environmental cues for biological rhythms
Ghrelin
first hormone known to stimulate human appetite. Produced primarily in the stomach, where it is secreted into the bloodstream and travels to the brain where it activates "Hunger detector" areas of the hypothalamus and stimulate appetite.
The ventral lateral (VL) and the ventral anterior Nucleus (6 of 7)
have two-way connections to the cerebellum, basal ganglia, and parts of the cortex involved in motor activity and the anterior nuclei are connected to limbic system area's concerned with emotions and memory.
Regulation of sexual activity and reproductive cycle
hypothalamus regulates sexual activity and the reproductive cycle through its control of the endocrine system. Hormonal receptors within the hypothalamus constantly monitor levels of sex hormones in the bloodstream, and generally keep hormonal levels within a narrow set-point range. When it detects that concentrations of a sex hormone in the blood have dropped below the set-point, it releases its own sex hormone called gonadotropin-releasing hormone (GnRH) to pituitary gland.
Types of generated responses of hormones
immediate response (i.e., the hormone adrenaline plays a key role in stimulating immediate fight/flight response to danger) and delayed and long term responses (i.e., growth hormones and sex hormones stimulate slow, long-lasting effects)
(VMN) ventral-medial nucleus
in contrast to the SDN of the hypothalamus is more important for female sexual behavior. Stimulation of this area triggers sexual activity in female rats and Lesioning reduces sexual responsiveness.
Melatonin in the pineal gland
increases alpha/theta EEG activity and slows cognitive and psychomotor performance.
Latin: INFRA
infradian rhythms infr=below
Posterior Pituitary
intricately connected with the hypothalamus through more than 100,000 fibers that extend from the supra-optic and periventricular nuclei of the hypothalamus. It releases two important hormones manufactured by the hypothalamus: oxytocin, the so called, "cuddle chemical" which is also involved in birth and milk production, and vasopressin (also called "anti diuretic hormone") which influences blood pressure and enables the kidneys to reabsorb water and secrete highly concentrated urine. In males, vasopressin may be involved in monogamous behavior.
Leptin
is a hormone secreted by fat cells. When released into the bloodstream, it acts on the hypothalamus to regulate appetite. When ______ binds with receptors in the hypothalamus it inhibits the release of appetite stimulating transmitters. Appetite then turns off and the metabolism is increased. When fat stores in the body decrease, _______ secretion decrease, metabolism slows and appetite is stimulated.
The lateral geniculate nucleus (LG) (2 of 7)
is a relay station for visual input. It receives input from the superior colliculus in the mid brain and relays it to the visual cortex in the occipital lobe of the cortex.
the Mediodorsal Nucleus (MN) (7 of 7)
is also involved in emotions and is connected to parts of the limbic system, temporal lobes and prefrontal cortex.
Hypothalamus and Homeostasis
is responsible for maintaining a state of physiological constantly or balance: without homeostasis it may lead to death or a disease, a condition known as "homeostatic imbalance"
Hunger detector
lateral hypothalamus (LH) serves as the brains ______________ ____________.
Circadian Rhythms
occur on an approx. 24 hour cycle- variety of psychobiological activities include: sleep/wake cycle, hormonal levels, neurotransmitter levels, physical activity, body temperature, blood pressure, heart rate & Blood sugar levels.
the Medial preoptic area (MPOA) in hypothalamus
plays a major role in stimulating copulatory behaviors in males. During intercourse this becomes active and when this are is stimulated, it triggers spontaneous copulatory behavior in both male and female rats.
VMH- Ventral-Medial Hypothalamus also:
plays a role in regulating the body's metabolism by stimulating the secretion of insulin, the hormone that regulates fat and sugar metabolism.
two lobes of the pituitary gland.
posterior pituitary and the anterior pituitary.
Peptide YY (PYY)
powerful appetite suppressant that is released into the bloodstream by cells in the intestines shortly after eating. Gives you a sense of fullness.
Hypothalamus: The central Coordinating Center
receives input from almost every area of the body, all the senses of the blood stream, the brain stem, limbic system and cerebral cortex and can be thought of as the brain's central coordinating center. from these sources enable the hypothalamus to monitor and coordinate the activities of the various organs, the chemical and nutritive state of blood, and levels of certain NT's and hormones.
Anterior Nucleus (AN) (3 of 7)
receives input from the hypothalamus and has output to the cingulate gyrus, an important part of the limbic system involved in emotions and social behavior.
the VPL (ventral posterior lateral nuclei) (5 of 7)
relays somatosensory to the cerebral cortex (touch, tickle, pressure, temperature and pain)
Ultradian Rhythms
repeat more than once a day: i.e., breathing, sleep cycles, eating, bathroom, etc.
Master control for the Endocrine system
the hypothalamus is the master controller of the endocrine system by controlling the activity of the pituitary gland, the body's master endocrine gland, which is suspended from the bottom of the hypothalamus. the pituitary consists of two lobes, anterior and posterior, with separate functions.
Two major outputs of the Hypothalamus
the hypothalamus regulates homeostasis through its two main outputs: the ANS and the endocrine system
SCN Suprachiasmatic Nuclei
the master body clock. most biological rhythms are controlled by the bodys biological clock. Pin head in size is a tiny part of the hypothalamus with only about , 20,000 neurons, found just above "Supra" the point in the brain where the optic nerves cross called the "optic chiasm". It receives information regarding light and darkness levels in the environment directly from the optic nerves initiating a lot of biological responses.
GnRH instructs:
the pituitary to release its sex hormones, luteinizing sex (LH) and follicle stimulating hormone (FSH) which signal the sex gland that signal the sex gland that produces the hormone to make more. When the hypothalamus detects that the set-point has reached its normal range, then it will again signal the pituitary to slow down.
Latin: Ultra
ultradian rhythm ultra=beyond dia=day
Anterior Pituitary
unlike the posterior pituitary, the anterior pituitary is connected to the hypothalamus only by special capillaries. The hypothalamus controls the activity of the anterior pituitary by secreting its own special hormones- called releasing hormones and inhibiting hormones. Acting on the signals it receives from the hypothalamus, the anterior pituitary can release its own hormones- called "stimulating hormones" into the bloodstream. These include: thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH), follicle stimulating hormones (FAH), prolactin (PRL), and growth hormone (GH). acting in response to the hormonal signals they receive from the anterior pituitary, endocrine glands release their hormones- called "final hormones" into the bloodstream. These hormones affect cells in other parts of the body and stimulating a variety of changes within the body.
prostaglandin
when bacteria enters the body, cells in the hypothalamus release a chemical called prostaglandin. Which will trigger an increase in body temperature and the fever kills the bacteria. Aspirin reduces fever by blocking the production and release of prostaglandin by the hypothalamus.
Hypothalamus and the ANS
when parts of the Hypothalamus are stimulated, signals travel to the medulla where cells that activate the ANS are located. As you recall, the ANS is composed of two complementary systems: SNS (Sympathetic Nervous System) and PNS (Parasympathetic Nervous System). Both systems connect the hypothalamus with the muscles of internal organs, glands, blood vessels, and skin. The sympathetic branch generates physiological arousal, while activation of the parasympathetic generates physiological calm ("rest and digest")
