Cortex, limbic etc


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  • Mention angular gyrus - dyslexia
  • PET scan (vanders)
  • * Berne p209-210
  • 1. The prefrontal cortex and other areas of association cortex provide the limbic system with information based on previous learning and currently perceived needs. Inputs from the brainstem provide visceral and somatic sensory signals, including tactile, pressure, pain, and temperature information from the skin and sexual organs and pain information from the visceral organs. 2. the brainstem has reciprocal connections with the hypothalamus (see Fig. 7.11). As noted above, all ascending sensory systems in the brainstem send axon collaterals to the reticular formation which, in turn, innervates the limbic system, particularly via monoaminergic pathways. The reticular formation also forms the ascending reticular activating system, which serves not only to arouse the cortex but also to impart an emotional tone to the sensory information transmitted nonspecifically to the cerebral cortex.
  • *Classically, the hypothalamus has been considered a grouping of regulatory centers governing homeostasis. With respect to eating, the ventromedial nucleus of the hypothalamus was thought to serve as a satiety center and the lateral hypothalamic area as a feeding center. Together, these areas would then coordinate the processes that govern eating behavior and the subjective perception of satiety. These hypothalamic areas also influence the secretion of hormones, particularly from the thyroid gland, adrenal gland, and pancreatic islet cells, in response to changing metabolic demands. Although crude lesion and stimulation studies supported the satiety versus feeding center model of the regulation of feeding, this simplistic model is no longer tenable.
  • Propriomelanocortin (POMC) Several orexigenic (stimulating appetite) and anorexigenic (causing loss of appetite) peptides and neurotransmitters contribute to the regulation of energy balance (Table 7.1). Some, such as leptin and insulin, act on a long time course to maintain body weight and blood glucose levels, and others, such as cholecystokinin (CCK) and ghrelin, act on a shorter time course to regulate initiation or cessation of a meal. Many of these signals are detected in the arcuate nucleus (ARC) of the hypothalamus, some by directly bathing ARC neurons and others by relaying through vagal inputs to the hypothalamus (Fig. 7.3). Within the ARC, two groups of neurons are critical. One group expresses neuropeptide Y (NPY); activation of these neurons causes increased food intake and decreased energy expenditure. The other group expresses P.125 pro-opiomelanocortin (POMC), which is a precursor for melanocortin peptides; activation of these neurons causes decreased food intake and increased energy expenditure. Outputs from the ARC that mediate alterations in feeding or energy expenditure include projections to the lateral hypothalamus, dorsomedial nucleus, and paraventricular nucleus, as well as a variety of structures in the brainstem and forebrain limbic system involved in motivated behavior (see Fig. 7.3). Direct output to parasympathetic and sympathetic preganglionic neurons in the brainstem and spinal cord derives from the paraventricular nucleus and the ARC. The paraventricular nucleus engages the endocrine system through its regulation of the pituitary gland.
  • *At a critical period in fetal development, circulating testosterone secreted by the testes of a male fetus changes the characteristics of cells in the preoptic area that are destined later in life to secrete GnRH. These cells, which would secrete GnRH cyclically at puberty had they not been exposed to androgens prenatally, are transformed into cells that secrete GnRH continually at a homeostatically regulated level. As a result, males exhibit a steady-state secretion rate for gonadotropic hormones and, consequently, for testosterone (see Chapter 36). In the absence of androgens in fetal blood during development, the preoptic area remains unchanged, so that at puberty the GnRH-secreting cells begin to secrete in a cyclic pattern. This pattern is reinforced and synchronized throughout female reproductive life by the cyclic feedback of ovarian steroids, estradiol and progesterone, on secretion of GnRH by the hypothalamus during the menstrual cycle (see Chapter 37). Steroid levels during prenatal and postnatal development are known to mediate differentiation of sexually dimorphic regions of the brain of most vertebrate species. Sexually dimorphic brain anatomy, behavior, and susceptibility to neurological and psychiatric illness are evident in humans. **
  • New rhordes: The brainstem contains anatomic groupings of cell bodies clearly identified as the nuclei of cranial sensory and motor nerves or as relay cells of ascending sensory or descending motor systems. The remaining cell groups of the brainstem, located in the central core, constitute a diffuse-appearing system of neurons with widely branching axons, known as the reticular formation. Neurons in the reticular formation serve many functions, including regulation of the sleep/wake cycle, modulation of pain, and regulation of muscle tone.
  • Purpose of sleep – unknown !!! (berne)
  • EEG recordings of sleeping subjects in laboratory settings reveal that the brain's electrical activity varies as the subject passes through cycles of slow-wave sleep, then REM sleep, on through the night. A normal sleep cycle begins with slow-wave sleep, four stages of increasingly deep sleep during which the EEG becomes progressively slower in frequency and higher in amplitude. Stage 4 is reached at the end of about an hour, when delta waves are observed (see Fig. 7.7). The subject then passes through the same stages in reverse order, approaching stage 1 by about 90 minutes, when a REM period begins, followed by a new cycle of slow-wave sleep. Slow-wave sleep is characterized by decreased heart rate and blood pressure, slow and regular breathing, and relaxed muscle tone. Stages 3 and 4 occur only in the first few sleep cycles of the night. In contrast, REM periods increase in duration with each successive cycle, so that the last few cycles consist of approximately equal periods of REM sleep and stage 2 slow-wave sleep.
  • to determine whether erectile failure is based on a neurological or a vascular defect (in which case, erection does not accompany REM sleep).
  • *Many of us have experienced this muscle paralysis on waking from a bad dream, feeling momentarily incapable of running from danger. In certain sleep disorders in which skeletal muscle contraction is not temporarily paralyzed in REM sleep, subjects act out dream sequences with disturbing results, with no conscious awareness of this happening.
  • Green trace (left) tonic phase grand mal; (right) clonic phase grand mal Psychomotor is a form of focal epilepsy
  • Cortex, limbic etc

    1. 1. Cerebral Cortex
    2. 2. Layers <ul><li>Most incoming sensory signals: IV </li></ul><ul><li>Most output signals leave cortex: V & VI </li></ul><ul><li>To brain stem and SC: V </li></ul><ul><li>Fibers to thalamus: VI </li></ul><ul><li>Intracortical association functions: I,II,III </li></ul>
    3. 3. Functional Areas Stuttering & Laughter !
    4. 4. Association Areas <ul><li>PRT Association area: </li></ul><ul><ul><li>Continous info about body spatial coordinates </li></ul></ul><ul><ul><li>Language comprehension </li></ul></ul><ul><ul><li>Initial processing of visual language (reading) </li></ul></ul><ul><ul><li>Are for naming objects </li></ul></ul>
    5. 5. Specific Functional Areas
    6. 6. Face Recognition
    7. 7. Wernicke ’ s Area <ul><li>Plays the greatest single role of any part of the cerebral cortex for the higher comprehension levels of brain function that we call intelligence </li></ul>
    8. 8. Cerebral Dominance? <ul><li>Dominant & nondominant hemispheres </li></ul><ul><li>Categorical hemisphere </li></ul><ul><ul><ul><li>Sequential-analytic processes </li></ul></ul></ul><ul><ul><ul><ul><li>Language </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Analytical reasoning </li></ul></ul></ul></ul><ul><li>Representational hemisphere </li></ul><ul><ul><ul><li>Visuospatial relations </li></ul></ul></ul><ul><ul><ul><ul><li>Identification of objects by their form </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Recognition of faces </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Recognition of musical themes </li></ul></ul></ul></ul>
    9. 9. Lesions of Representational & Categorical Hemispheres   <ul><li>Lesions of categorical hemisphere: </li></ul><ul><ul><ul><li>Language disorders </li></ul></ul></ul><ul><ul><ul><li>Disturbed about their disability and often depressed </li></ul></ul></ul><ul><li>Lesions of representational hemisphere: </li></ul><ul><ul><ul><li>No language disorders </li></ul></ul></ul><ul><ul><ul><li>Sometimes unconcerned and even euphoric! </li></ul></ul></ul><ul><ul><ul><li>Astereognosis —the inability to identify objects by feeling them </li></ul></ul></ul><ul><ul><ul><li>Lesions of inferior parietal lobule cause unilateral inattention and neglect </li></ul></ul></ul><ul><ul><ul><li>Inability to tell a story or make a joke </li></ul></ul></ul>
    10. 10. Language <ul><li>Language is one of the fundamental bases of human intelligence and a key part of human culture </li></ul><ul><li>Areas concerned: </li></ul><ul><ul><ul><li>Wernicke's area connected via Arcuate fasciculus to Broca's area </li></ul></ul></ul><ul><li>2 nd language </li></ul><ul><ul><ul><li>Broca’s area concerned is different from that associated with native language </li></ul></ul></ul><ul><ul><ul><li>Children learning 2 languages simultaneously have the same Broca’s area dealing with both languages </li></ul></ul></ul>
    11. 11. <ul><li>Two aspects: </li></ul><ul><ul><ul><li>Sensory </li></ul></ul></ul><ul><ul><ul><ul><li>Auditory input </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Visual input </li></ul></ul></ul></ul><ul><ul><ul><li>Motor </li></ul></ul></ul>
    12. 12. Language Disorders <ul><li>Aphasias </li></ul><ul><ul><ul><li>Abnormalities of language functions that are not due to defects of vision or hearing or to motor paralysis </li></ul></ul></ul><ul><ul><ul><li>Caused by lesions in categorical hemisphere </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Most common cause is embolism or thrombosis of a cerebral blood vessel </li></ul></ul></ul></ul></ul><ul><ul><li>Wernicke’s Aphasia </li></ul></ul><ul><ul><ul><li>Global Aphasia </li></ul></ul></ul><ul><ul><li>Motor Aphasia </li></ul></ul><ul><ul><ul><ul><li>Dysarthria </li></ul></ul></ul></ul><ul><li>Receptive and expressive aphasia* </li></ul>
    13. 13. Language – Chair! &quot;I know what it is . . . I have a lot of them.&quot; Anomic (angular gyrus) &quot;Flair . . . no, swair . . . tair.&quot; Fluent (areas 40, 41, and 42; conduction aphasia) &quot;Stool&quot; or &quot;choss&quot; (neologism) Fluent (Wernicke’s area) &quot;Tssair&quot; Nonfluent (Broca’s area) Characteristic Naming Errors Type of Aphasia and Site of Lesion
    14. 14. Thoughts <ul><li>A “pattern” of stimulation of many parts of the nervous system at the same time, probably involving most importantly the cerebral cortex, thalamus, limbic system, and upper reticular formation of the brain stem. ( Holistic theory ) </li></ul>
    15. 15. Memory <ul><li>Stored in brain by changing basic sensitivity of synaptic transmission b/w neurons as a result of previous neural activity </li></ul><ul><li>New (facilitated) pathways - memory traces </li></ul><ul><ul><ul><li>Once traces are established - they can be selectively activated by the thinking mind to reproduce the memories </li></ul></ul></ul>
    16. 16. Classification <ul><li>Time-wise </li></ul><ul><ul><ul><li>Short-term </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Presynaptic ++ or -- </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Intermediate long-term </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Reversible chemical/structural changes (pre- or postsynaptic) </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Long-term </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Actual structural changes </li></ul></ul></ul></ul></ul><ul><li>Functional </li></ul><ul><ul><ul><li>Declarative </li></ul></ul></ul><ul><ul><ul><li>Skill </li></ul></ul></ul>
    17. 17. Classification <ul><li>Explicit or declarative memory </li></ul><ul><ul><ul><li>Associated with consciousness/awareness </li></ul></ul></ul><ul><li>Implicit or nondeclarative memory </li></ul><ul><ul><ul><li>Does not involve awareness </li></ul></ul></ul>
    18. 18. Hippocampus <ul><li>Storage of memories </li></ul><ul><li>Lesion causes: </li></ul><ul><ul><ul><li>Anterograde & </li></ul></ul></ul><ul><ul><ul><li>Retrograde amnesia </li></ul></ul></ul><ul><ul><ul><li>Cannot establish new declarative memories </li></ul></ul></ul><ul><ul><ul><li>Can establish skill (reflexive) memories </li></ul></ul></ul>
    19. 19. Strangeness & Familiarity <ul><li>Some parts of temporal lobes causes a change in interpretation of one's surroundings </li></ul><ul><ul><ul><li>déjà vu phenomenon! </li></ul></ul></ul>
    20. 20. <ul><li>LIMBIC SYSTEM </li></ul>
    21. 21. Limbic System - General <ul><li>Comprises large areas of forebrain </li></ul><ul><ul><ul><li>Where emotions are generated & responses to emotional stimuli are coordinated </li></ul></ul></ul><ul><li>Major psychiatric disorders are linked to limbic system mafunction </li></ul><ul><ul><ul><li>bipolar disorder, </li></ul></ul></ul><ul><ul><ul><li>major depression, </li></ul></ul></ul><ul><ul><ul><li>schizophrenia, </li></ul></ul></ul><ul><ul><ul><li>dementia </li></ul></ul></ul>
    22. 23. Functional Anatomy of Limbic System
    23. 24. Functional Anatomy of Limbic System
    24. 25. Limbic System - General
    25. 26. <ul><li>HypoT Nuclei: </li></ul><ul><ul><li>Anterior </li></ul></ul><ul><ul><ul><li>Medial preoptic </li></ul></ul></ul><ul><ul><ul><li>Paraventricular </li></ul></ul></ul><ul><ul><ul><li>Supraoptic </li></ul></ul></ul><ul><ul><ul><li>Anterior hypoT areas </li></ul></ul></ul><ul><ul><ul><li>Post. Preoptic </li></ul></ul></ul><ul><ul><li>Posterior </li></ul></ul><ul><ul><ul><li>Mamillary body </li></ul></ul></ul><ul><ul><ul><li>Dorsomedial </li></ul></ul></ul><ul><ul><ul><li>Posterior hypoT </li></ul></ul></ul><ul><ul><ul><li>Perifornical </li></ul></ul></ul><ul><ul><ul><li>Ventromedial </li></ul></ul></ul><ul><ul><ul><li>Arcuate & periventricular </li></ul></ul></ul><ul><ul><ul><li>Lateral hypoT area </li></ul></ul></ul>
    26. 27. Hypothalamic Nuclei
    27. 28. Hypothalamic Nuclei - Functions <ul><ul><li>Anterior </li></ul></ul><ul><ul><ul><li>Paraventricular </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Oxytocin release </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Water conservation </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Medial preoptic </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Bladder contraction </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Decreased HR </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Decreased BP </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Post. Preoptic & anterior hypoT areas </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Body temp regulation </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Panting, sweating </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Thyrotropin inhibitor </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sexual drive </li></ul></ul></ul></ul></ul><ul><ul><ul><li>Supraoptic </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Vasopressin release </li></ul></ul></ul></ul></ul>
    28. 29. Hypothalamic Nuclei - Functions <ul><li>Posterior </li></ul><ul><ul><li>Dorsomedial </li></ul></ul><ul><ul><ul><ul><ul><li>GI ++ </li></ul></ul></ul></ul></ul><ul><ul><li>Posterior hypoT </li></ul></ul><ul><ul><ul><ul><ul><li>Increased BP </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Pupillary dilation </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Shivering </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sexual drive </li></ul></ul></ul></ul></ul><ul><ul><li>Perifornical </li></ul></ul><ul><ul><ul><ul><ul><li>Hunger </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Increased BP </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Rage </li></ul></ul></ul></ul></ul><ul><ul><li>Ventromedial </li></ul></ul><ul><ul><ul><ul><ul><li>Satiety*, decreased eating, and tranquility </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Neuroendorine control </li></ul></ul></ul></ul></ul><ul><ul><li>Mamillary body </li></ul></ul><ul><ul><ul><ul><ul><li>Feeding reflexes </li></ul></ul></ul></ul></ul><ul><ul><li>Arcuate & periventricular </li></ul></ul><ul><ul><ul><ul><ul><li>Neuroendocrine control </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Fear & punishment reactions </li></ul></ul></ul></ul></ul><ul><ul><li>Lateral hypoT area </li></ul></ul><ul><ul><ul><ul><ul><li>Thirst & hunger*, rage, fighting </li></ul></ul></ul></ul></ul>
    29. 30. Hypothalamus And Feeding behaviour <ul><li>Food intake , energy expenditure & reproductive function – go together </li></ul><ul><li>HypoT regulates </li></ul><ul><ul><li>Caloric intake, Use & Storage </li></ul></ul><ul><ul><ul><li>In a manner that tends to maintain the body weight in adulthood </li></ul></ul></ul><ul><ul><ul><li>Body weight ‘set point’ to stabilize body weight is remarkably constant! </li></ul></ul></ul>
    30. 31. Hypothalamus Controls Gonads & Sexual Activity <ul><li>Anterior & preoptic hypothalamic areas: </li></ul><ul><ul><ul><li>Sites for regulating gonadotropic hormone secretion and sexual behavior </li></ul></ul></ul><ul><ul><ul><li>Preoptic area neurons secrete GnRH - at puberty </li></ul></ul></ul><ul><ul><ul><ul><li>Contain receptors for gonadal steroid hormones (testosterone, estradiol) - regulate GnRH secretion* </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Sexually dimorphic nucleus (SDN)** </li></ul></ul></ul></ul>
    31. 32. Hypothalamus Contains the “Biological Clock” <ul><li>Suprachiasmatic nucleus (SCN) </li></ul><ul><ul><li>Center in hypoT that serves as the brain's biological clock </li></ul></ul>
    32. 33. “ Reward” & “Punishment” Function of Limbic System <ul><li>Reward Centers </li></ul><ul><ul><ul><li>Lateral & ventromedial nuclei of the hypothalamus </li></ul></ul></ul><ul><ul><ul><li>Septum </li></ul></ul></ul><ul><ul><ul><li>Amygdala </li></ul></ul></ul><ul><ul><ul><li>Certain areas of thalamus & basal ganglia </li></ul></ul></ul><ul><li>Punishment Centers </li></ul><ul><ul><ul><li>Central gray area surrounding aqueduct of Sylvius (mesencephalon) </li></ul></ul></ul><ul><ul><ul><li>Periventricular zones of hypoT & thalamus </li></ul></ul></ul><ul><ul><ul><li>++ punishment centers can frequently -- reward & pleasure centers completely!! </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Punishment & fear can take precedence over pleasure & reward </li></ul></ul></ul></ul></ul>
    33. 34. Behavioral f n of Hippocampus <ul><li>Almost any type of sensory experience causes: ++ hippocampus </li></ul><ul><li>Hippocampus in turn distributes it to: </li></ul><ul><ul><ul><ul><li>Anterior thalamus </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Hypothalamus </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Other parts of limbic system </li></ul></ul></ul></ul><ul><li>Thus incoming sensory signals can initiate behavioral reactions </li></ul><ul><li>Declarative memories require hippocampus </li></ul>
    34. 35. Functions of Amygdala <ul><li>Location </li></ul><ul><ul><ul><ul><li>Complex of multiple small nuclei located immediately beneath cerebral cortex of each temporal lobe (medial anterior pole) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Extensive bidirectional connections with hypoT + areas of limbic system </li></ul></ul></ul></ul><ul><li>Connections </li></ul><ul><ul><li>The “ window ” through which the limbic system sees the place of the person in the world </li></ul></ul><ul><ul><ul><ul><li>Input </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Neuronal signals from all portions of limbic cortex </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Neocortex of </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Temporal lobe </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Parietal lobe </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Occipital lobe </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>(i.e. auditory & visual association areas) </li></ul></ul></ul></ul></ul>Output Same areas of cortex Hippocampus Thalamus HypoT
    35. 36. Functions of Amygdala <ul><li>Mediated via hypoT: </li></ul><ul><ul><li>Increases or decreases in BP </li></ul></ul><ul><ul><li>Increases or decreases in HR </li></ul></ul><ul><ul><li>Increases or decreases in GI motility & secretion </li></ul></ul><ul><ul><li>Defecation or micturition </li></ul></ul><ul><ul><li>Pupillary dilation (or, rarely, constriction) </li></ul></ul><ul><ul><li>Piloerection </li></ul></ul><ul><ul><li>Secretion of various anterior pituitary hormones </li></ul></ul><ul><ul><ul><li>especially gonadotropins & adrenocorticotropic hormone </li></ul></ul></ul>
    36. 37. Functions of Amygdala <ul><li>Involuntary movements </li></ul><ul><ul><ul><li>tonic movements </li></ul></ul></ul><ul><ul><ul><ul><ul><li>raising the head or bending the body </li></ul></ul></ul></ul></ul><ul><ul><ul><li>circling movements </li></ul></ul></ul><ul><ul><ul><li>occasionally clonic, rhythmical movements </li></ul></ul></ul><ul><ul><ul><li>different types of movements associated with olfaction and eating </li></ul></ul></ul><ul><ul><ul><ul><li>licking, chewing, and swallowing. </li></ul></ul></ul></ul>
    37. 38. Functions of Amygdala <ul><li>Behavioral </li></ul><ul><ul><ul><li>++ certain areas causes: </li></ul></ul></ul><ul><ul><ul><ul><li>Rage, escape, punishment, severe pain, and fear similar to the rage pattern elicited from hypothalamus </li></ul></ul></ul></ul><ul><ul><ul><li>++ of other areas causes: </li></ul></ul></ul><ul><ul><ul><ul><li>Pleasure & reward </li></ul></ul></ul></ul><ul><ul><ul><li>Sexual activities include </li></ul></ul></ul><ul><ul><ul><ul><li>Erection </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Copulatory movements </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ejaculation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ovulation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Uterine activity </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Premature labor </li></ul></ul></ul></ul>
    38. 39. Klüver-Bucy Syndrome <ul><li>Anterior parts of both temporal lobes destroyed </li></ul><ul><ul><ul><li>Also removes bilateral amygdalas </li></ul></ul></ul><ul><ul><ul><ul><li>Fearlessness </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Extreme curiosity about everything </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Forgets rapidly </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Tendency to place everything in mouth & sometimes even tries to eat solid objects </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Vicious and unnatural sex drive </li></ul></ul></ul></ul>
    39. 40. <ul><li>RETICULAR FORMATION, SLEEP & BRAIN WAVES </li></ul>
    40. 41. Reticular Formation <ul><li>RF </li></ul><ul><ul><li>Located in the central core of brainstem </li></ul></ul><ul><ul><li>Diffuse-appearing system of neurons </li></ul></ul><ul><ul><li>Serve in: </li></ul></ul><ul><ul><ul><ul><li>Sleep/wake cycle regulation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pain modulation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Muscle tone regulation </li></ul></ul></ul></ul>
    41. 42. RF - Consciousness and Arousal <ul><li>RF also has neuronal systems for: </li></ul><ul><ul><li>1. Ascending RAS </li></ul></ul><ul><ul><ul><li>Sensory ascending tracts - thalamus - sensory cortex </li></ul></ul></ul><ul><ul><ul><li>Also give collaterals to RF while in brainstem </li></ul></ul></ul><ul><ul><ul><ul><li>RF projects these in intralaminar nuclei of thalamus (innervating large areas of cerebral cortex + limbic) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Function: Arousal </li></ul></ul></ul></ul><ul><ul><li>2. Regulation of sleep/wake cycle & consciousness </li></ul></ul>
    42. 43. Sleep <ul><li>Unconsciousness from which the person can be aroused by sensory or other stimuli </li></ul><ul><ul><ul><li>Coma - unconsciousness from which the person cannot be aroused </li></ul></ul></ul><ul><li>Types of Sleep </li></ul><ul><ul><ul><li>S low-wave sleep </li></ul></ul></ul><ul><ul><ul><ul><li>Brain waves are very strong and very low frequency </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Most sleep per night </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Very restful </li></ul></ul></ul></ul><ul><ul><ul><li>R apid eye movement sleep (REM sleep) </li></ul></ul></ul><ul><ul><ul><ul><li>Eyes undergo rapid movements </li></ul></ul></ul></ul><ul><ul><ul><ul><li>25 % of sleep time in young adults; each episode normally recurs about every 90 minutes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Not so restful </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Associated with vivid dreaming </li></ul></ul></ul></ul><ul><li>Sleep (induction) is an active process! </li></ul>
    43. 44. Sleep
    44. 45. REM Sleep (Paradoxical sleep) <ul><li>Unsynchronized, high-frequency, low-amplitude waves (i.e., a beta rhythm) </li></ul><ul><ul><ul><li>Yet subject is as difficult to arouse as when in stage 4 slow-wave sleep! </li></ul></ul></ul><ul><ul><ul><li>ANS is ++ </li></ul></ul></ul><ul><ul><ul><ul><li>BP & HR are increased/ breathing irregular </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Males: </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>ANS reflex induced penile erection in REM sleep </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Used in diagnosing impotence </li></ul></ul></ul></ul></ul>
    45. 46. REM Sleep (Muscle Paralysis) <ul><li>Most voluntary muscles are temporarily paralyzed </li></ul><ul><ul><ul><li>Exceptions: </li></ul></ul></ul><ul><ul><ul><ul><li>Muscles of respiration </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Extraocular muscles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Muscles of the middle ear, which protect the inner ear </li></ul></ul></ul></ul><ul><li>Caused by active --- of MNs mediated by a group of neurons located close to locus ceruleus (brainstem)* </li></ul>
    46. 47. Sleep Durations <ul><li>Varies with developmental stage: </li></ul><ul><ul><ul><li>Newborns sleep: approx.16 hours/day </li></ul></ul></ul><ul><ul><ul><ul><li>About 50% - REM sleep. </li></ul></ul></ul></ul><ul><ul><ul><li>Normal adults: 7-8 hours/day, </li></ul></ul></ul><ul><ul><ul><ul><li>About 25% - REM sleep. </li></ul></ul></ul></ul><ul><li>Percentage of REM declines further with age, together with a loss of ability to achieve stages 3 & 4 of slow-wave sleep </li></ul>
    47. 48. Electroencephalogram (EEG) <ul><li>Influence of ascending RAS on brain's activity - monitored via EEG </li></ul><ul><li>Benefits of EEG: </li></ul><ul><ul><ul><li>Noninvasive tool </li></ul></ul></ul><ul><ul><ul><li>Measures simultaneously (via multiple leads) electrical activity of major areas of cerebral cortex </li></ul></ul></ul><ul><ul><ul><li>Best diagnostic tool available for detecting abnormalities in electrical activity </li></ul></ul></ul><ul><ul><ul><ul><ul><li>Epilepsy </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Sleep disorders </li></ul></ul></ul></ul></ul><ul><li>Detected electrical activity reflects </li></ul><ul><ul><ul><li>Extracellular recording of many postsyn. potentials in cortical neurons underlying an electrode </li></ul></ul></ul><ul><ul><ul><ul><li>The electric potentials are summated! </li></ul></ul></ul></ul>
    48. 49. EEG <ul><li>Frequency: <1 to 30 Hz </li></ul><ul><li>Wave amplitude: 20-100 µV </li></ul><ul><li>Typical pattern of waves in various situations </li></ul><ul><ul><ul><li>In conscious states: High freq+low amplitude (since many neurons discharge asynchronously ) </li></ul></ul></ul><ul><ul><ul><li>In deep sleep : Low freq+high amplitude (EEG is synchronized ) </li></ul></ul></ul><ul><ul><ul><li>Absent EEG: Death (US) </li></ul></ul></ul><ul><ul><ul><ul><ul><li>2 nd year students (Pak)…! </li></ul></ul></ul></ul></ul>
    49. 50. EEG <ul><li>Alpha: awake (eyes closed) </li></ul><ul><li>Beta: awake (eyes open) </li></ul><ul><li>Theta: sleep </li></ul><ul><li>Delta: deep sleep/coma </li></ul>
    50. 51. Epilepsy <ul><li>Characterized by uncontrolled excessive activity of either part or all of CNS </li></ul><ul><li>Types: </li></ul><ul><ul><ul><li>Grand mal epilepsy </li></ul></ul></ul><ul><ul><ul><li>Petit mal epilepsy </li></ul></ul></ul><ul><ul><ul><li>Focal epilepsy </li></ul></ul></ul>
    51. 52. Grand Mal Epilepsy <ul><li>Tonic-Clonic seizures </li></ul>