Neuroscience Optional Lecture. The limbic system the emotional brain. Emotion, behaviour, motivation, long-term memory, olfaction

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1 Neuroscience Optional Lecture The limbic system the emotional brain Emotion, behaviour, motivation, long-term memory, olfaction

2 Emotion Conscious experience intense mental activity and a certain degree of pleasure and displeasure Arousal Can change metabolic and organ functions change in behavior Often intertwined with mood, temperament, personality, disposition and motivation. Cognitive process: understanding through thought, experience and senses

3 How are we wired? CNS vs Peripheral nervous system Somatic vs autonomous nervous system Motor vs sensory impulses Limbic system vs consciousness * Cortex control brain, social and environmental integration * Limbic system emotional brain

4 Fight or flight Epinephrine Activation of the sympathetic nervous system has the following effects: - opens the eyelids - stimulates the sweat glands - dilates the blood vessels in large muscles - constricts the blood vessels in the rest of the body - increases the heart rate - opens up the bronchial tubes of the lungs - inhibits the secretions in the digestive system

5 The parasympathetic nervous system brings the body back from the emergency status - pupil constriction - activation of the salivary glands - stimulating the secretions of the stomach - stimulating the activity of the intestines - stimulating secretions in the lungs - constricting the bronchial tubes - decreasing heart rate

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7 The limbic system - functions Generation of emotions: - hapiness, joy and euphoria - anger and rage - anxiety, fear and terror - sadness and depression Emotional state can affect the general level of alertness (via thalamus) - anxiety, fear, excitement, anger level of alertness - depresion, sadness level of alertness

8 The limbic system - functions Motivation - Passion! Short-term memory and learning (hippocampus) - Motivation and passion are needed for learning

9 The limbic system - functions Sense of smell - odors (like perfumes and aftershaves) affect emotions and attraction Sensitivity to pain - pain is an emotion; suffering Sexual behaviour

10 The limbic system - Components Subcortical areas: Septal nuclei, a set of structures that lie in front of the lamina terminalis, considered a pleasure zone. Amygdala, located deep within the temporal lobes and related with a number of emotional processes. It represents the main site of neural plasticity linked to fear. Nucleus accumbens: involved in reward, pleasure and addiction.

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12 Components Cortical areas: Limbic lobe (parahippocampal gyrus) Orbitofrontal cortex, a region in the frontal lobe involved in the process of decisionmaking. Piriform cortex, part of the olfactory system. Entorhinal cortex, related with memory and associative components. Hippocampus and associated structures, which play a central role in the consolidation of new memories. Fornix, a white matter structure connecting the hippocampus with other brain structures, particularly the mammillary bodies and septal nuclei

13 Prefronto-limbic circuitry age-related architecture

14 Hippocampus is involved with various processes relating to cognition. Spatial memory - an important component for the generation of new neurons, called adult-born granules (GC), in adolescence and adulthood - formation (dorsal hippocampus) and recall of the spatial memories (left hippocampus) Learning

15 Components Diencephalic structures: Hypothalamus: a center for the limbic system, connected with the frontal lobes, septal nuclei and the brain stem reticular formation, with the hippocampus and with the thalamus. It regulates a great number of autonomic processes: body temperature, blood sugar level, osmolarity. Mammillary bodies, part of the hypothalamus that receives signals from the hippocampus via the fornix and projects them to the thalamus. Anterior nuclei of thalamus receive input from the mammillary bodies. Involved in memory processing

16 Papez circuit

17 Clinical considerations Rabies: viral infection that affects the limbic system (medial hippocampus of the limbic system) anger/violence, fear/anxiety, Kluver Bucy syndrome Charles Whitman (murderer) - Murdered his mother and wife - Shot 38 people - Autopsy: tumour (the amydaloid nucleus of the limbic system)

18 Clinical considerations Schizofrenia: antisocial behaviour - dopamine - familial (genetic) Mania and depression 1. Mania: - high, impulsive, agressive - norepinephrine, serotonin 2. Depression: - sad, reclusive - norepinephrine - use antidepressant drugs

19 Sleep - a brief introduction

20 What is sleep? Sleep is a naturally recurring state of mind and body characterized by altered consciousness, relatively inhibited sensory activity, inhibition of nearly all voluntary muscles, and reduced interactions with surroundings.

21 Sleep studies The EEG is frequently used in the investigation of sleep disorders especially sleep apnoea. Polysomnography : EEG activity together with heart rate, airflow, respiration, oxygen saturation and limb movement

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24 Sleep patterns of EEG There are two different kinds of sleep: Rapid eye movement sleep (REM-Sleep) Non-REM sleep (NREM sleep)/ slow wave sleep NREM sleep is again divided into 4 stages (I to IV). The EEG pattern in sleep is given in the following table:

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26 Stage 1 Brain activation level reduced: low voltage EEG, diminished alpha activity, reduced frequency activity (theta) 3-7 Hz EOG Slow eye movement, low muscular activity EMG moderate reduced

27 Stage 2 low voltage EEG, mixed activity frequency, Hz sleep spindles associated with K complexes (diphasic waves, > 0,5 s) EOG slow, rare eye movements EMG moderate reduced muscular activity

28 Stage 3 EEG delta waves, 0,5-2 Hz & amplitude >75mV; covering around 20-50% from the analyzed epoch. EOG rare eye movements EMG moderate reduced muscular activity

29 Stage 4 EEG delta activity covering >50% from the epoch EOG rare eye movements EMG moderate - reduced

30 Why do we sleep?