1.  The limbic system and the hypothalamus  Behavioural & motivational mechanism of brain

2.  Limbic system  components ◦ Hypothalamus, hippocampus, anterior nucleus of thalamus, septal nuclei, amygdala, paraolfactory area, portions of basal ganglia

3. Medial forebrain bundle connects the limbic system to the brain stem Medial forebrain bundle connects the limbic system to the brain stem

4.  Border system  Entire neuronal circuitry ◦ controls emotional & motivational drives ◦ Controls Feeling of pleasure & punishment ◦ Is associated with the learning process ◦ Contains a Networks of distant neurons that function together

5.  Called the “emotional” brain  Is essential for flexible, stable, adaptive functioning  Links different areas so integration can occur ◦ Integration:  separate things are brought together as a whole ◦ Processes emotions and allocates attentional resources  Necessary for ◦ emotional balance ◦ adaptation to environmental demands (including fearful situations, etc.) ◦ creating meaningful connections with others (e.g. ability to interpret facial expressions and respond appropriately), and more…

6.  Componets  Hypthalamus – major part ◦ Behavioural control ◦ Control internal conditions (vegetative fxn)  Body temperature  Osmolality  Drives to drink or eat

7.  A major control headquarter for the limbic system  Output signals ◦ Brainstem (Reticular areas-mesencephalon, pons & medulla) then to autonomic nervous system ◦ Diencephalon, cerebrum ◦ Hypothalamic infundibulum  Control secretory function of  Posterior & anterior pituitary gland  Thus controls ◦ Pathways of the limbic system ◦ Most of the vegetative and endocrine function of the body ◦ Many aspects of emotional behaviour

9.  Vegetative & endocrine Functions ◦ Cardiovascular regulation ◦ Regulation of body temperature ◦ Regulation of body water ◦ Regulation of uterine contractility and milk ejection from the breasts ◦ Gastrointestinal and feeding regulation ◦ Control of endocrine hormone secretion by the anterior pituitary gland  Done through stimulation of specific areas/nuclei in the hypothalamus

11.  Its Behavioural function and other associated structures  Stimulation of or lesions in the hypothalamus  Have profound effects on Emotional behaviour 1. lateral hypothalamus  Increases the general level of activity of the animal  over rage & fighting 2. ventromedial nucleus  Sense of satiety, decreased eating & tranquility 3. thin zone periventricular nuclei ◦ Fear & punishment reactions 4. anterior & posterior portions ◦ Sex drive  Effects caused by hypothalamic lesions ◦ Opposite to stimulation

12.  Several limbic structures centered with the affective nature of sensory sensations  i.e weather the sensations  Pleasant/reward/satisfaction or  Unpleasant/punishment/aversion  Electrical stimulation of certain areas  pleases or satisfies the animal  where as stimulation of other areas  Causes Terror, pain, fear, defense, escape reactions

13.  Reward centres 1.Major reward centres  located along the course of the medial forebrain bundle  Lateral Ventromedial nuclei of the hypothalamus 2.Less potent  Septum  Amygdala  Thalamus  Basal ganglia  Basal tegmentum  of the mesencephalon

15.  Punishment centres ◦ Central gray area  surrounding the aqueduct of sylvius in mesencephalon  extending upward into the periventricular zone of the hypothalamus and thalamus  Less potent ◦ Amygdala & hippocampus

16.  Rage  It is associated with punishment centers  Its an emotional pattern that involves the punishment centers  characterized by strong stimulation of punishment centers especially periventricular zone of the hypothalamus & lateral hypothalamus

17. Rage pattern  causes the animal to 1.Develop a defense posture 2.extend its claws 3.lift its tails 4.Hiss 5.Spit 6.growl & 7.develop piloerection, wide open eyes and dilated pupils

18.  Further more ◦ Even the slightest provocation causes an immediate savage attach  Suppression of rage phenomenon ◦ Inhibitory signals from  Ventromedial nuclei  hypothalamus  Anterior cingulate gyri & subcortical gyri  Portion of hippocampi & anterior limbic cortex

19.  Stimulating rewards system  Leads to exactly opposite emotional behaviours pattern occurs  Placidity & tameness  Importance of Reward & punishment in behaviour  Control our  bodily activation  drives  aversions or  motivations  Tranquilizers  Administration of chlorplomazine  Inhibit both the reward and punishment centres  Decrease the affective reactivity of the animal

20. ◦ Habituation vs reinforcement ◦ Animals builds up strong memory traces for sensation that are either rewarding or punishing but conversely develop complete habituation to indifferent sensory stimulator  Therefore  99 % of the information is thrown away  Less than 1 % is selected for retention

21. Before Training – a transient orienting response is induced to the sound Training – sound is paired with the shock After Training – placement in the box induces freezing when the sound is present.

22.  The hippocampus ◦ Is the elongated portion of the cerebral cortex that folds inwards to form the ventral surface of the lateral ventricle ◦ Connections  portions of the cerebral cortex  basal structures of the limbic system  The amygdala  the hypothalamus  the septum &  the mammilary body

23.  Outgoing signals ◦ Anterior thalamus, hypothalamus & ◦ Other parts of the limbic system  Thru fornix- a major communication pathway  Stimulation of its different areas ◦ Pleasure ◦ Rage ◦ Passivity ◦ Excess ◦ sex drive

24.  It can become hyper-excitable sometimes  Hyperstimulation leads to ◦ Local epileptic seizures  With various psychomotor experiences such as  Olfactory, auditory, tactile & other types of hallucinations  Role in learning ◦ Bilateral removal e.g treatment of epilepsy  Individual presents with 1.Inability to learn 2.Recall most previously learned memories  Capable of short term memories (seconds- 1 or 2 minutes) 3.Cannot learn  new information based on verbal symbolism  the names of people meets daily

25.  Incapable of long term memories ◦ Without hippocampus ◦ Consolidation of long term memories  verbal or symbolic thinking type  poor or  does not take place

26.  Neurons at the pole of the temporal lobe below the cortex on the medial side  Greek name for almond shape  Has 3 nuclei, ◦ Basolateral ◦ corticomedial and ◦ central  Afferents 1.from all lobes of neocortex (temporal, parietal and occipital lobes) Especially from the auditory and visual association areas  Therefore called the window thru which the limbic system sees the place of the person in the world 2.& hippocampus and cingulate gyrus

28.  Basolateral nuclei ◦ receive sensory input (visual, gustatory, auditory and tactile) From all areas of limbic cortex  projects to cortex for perception of emotion  Corticomedial nuclei ◦ receive olfactory inputs  Central nuclei contain output neurons ◦ to hypothalamus (major portion) ◦ periaqueductal grey (in brainstem ) ◦ Back into the same cortical areas ◦ Hippocampus & Septum &Thalamus  for physiological responses

30.  Its stimulatory effect same as hypothalamus  The effects initiated through amygdala are then sent through hypothalamus  Efferent mediated thru hypothalamus Include  Increased or decreased ◦ arterial pressures ◦ Heart rate ◦ G.i.t motility & secretion  Defecation or micturation  Pupilary dilation or rarely constriction  Piloerection  Seceretion of various pituitary hormnones esp gonadotropins & ACTH

31.  Involuntary movements ◦ Tonic movements-raising the head or bending the body ◦ Circling movements ◦ Occasionally clonic, rhythmical movements ◦ Different types of movements associated with olfaction and eating such as licking, chewing and swallowing  Others  Rage, escape, punishment, severe pain & fear  Sexual activities  Erection  Copulatory movements  Ejeculation  Ovulation  Uterine activity and premature labour

32.  The Kluver-Bucy syndrome  Effects of bilateral ablation of the amygdala ◦ Behavioural characteristics a.Not afraid of anything b.Has extreme curiosity about everything c.Forgets rapidly d.Has a tendency to place everything in its mouth and sometimes tries to eat solid objects e.Has a sex drive too strong  attempts to copulate with  immature animals  animals of the wrong sex or  even animals of different species