The Brain and Neurones

1. The Brain and Neurones Psychopharmacology

2. The Human Brain • Complex • 1.4 kg in weight • Pre frontal cortex • 2% of body weight • 20% of oxygen • 15% of our cardiac input • 10% of all energy

3. The Blood Brain barrier • Brain protection system • The BBB is both; • A physical barrier that restricts the entrance of potentially harmful substances • A system of cellular transport mechanisms that controls the entrance of essential nutrients

4. Forebrain • Cerebrum and Cerebral cortex • Left and Right Hemispheres • Left Hemisphere- dominant hemisphere • Production of language • Mathematical ability • Problem solving • Right Hemisphere • - Creativity • - Spatial ability

6. Frontal Lobe • Located at the front of both cerebral hemispheres • Primary motor cortex • Pre motor cortex • Broca’s Area • Complex Functioning – personality, judgement, insight, reasoning, problem solving, abstract thinking and working memory

7. Parietal Lobe • Located behind frontal lobe • Somatosensory cortex • Spatial orientation, perception and comprehension of language function recognising objects by touch • Links visual and somatosensory information together • Neglect

8. Temporal Lobes • Located et each side of the brain • Involved in receiving and processing auditory information, higher order visual information , complex aspects of memory and language • Wernicke’s area

9. Occipital Lobe • Visual processing area • Corpus Callosum

10. Diencephalon • Thalamus • Filter for sensory information • Control of mood states • Body movement • Hypothalamus • Central control • Regulate autonomic, emotional, endocrine and somatic function • Stress

11. Hindbrain • Cerebellum • Equilibrium • Muscle tone • Postural control • Coordination of muscle movement • Pons • Relay station

12. Hindbrain • Medulla Oblongata • Skeletal muscles • Balance • Coordination • Inner ear sound impulses • Heart rate, vomiting, sneezing • Reticular formation • Arousal • Circadian rhythm • respiration

13. Basal ganglia • Muslce tone • Posture • Movement • Substantia Nigra

14. The Limbic System • Amygdala • Mood • Hippocampus • Memory

15. Neurones • The structural unit of the brain • Cell body • Axon • Dendrites • Synapse

17. Electrical Transmission • The Information that flows in the neurone • Approximately 10 billion neurons are responsible for receiving, organising and transmitting information in the central nervous system • Ions in the intracellular fluid (inside the cell) have a negative charge • Ions in extracellular fluid (outside the cell) have a positive charge attracting positively charged cells (cations) • ‘Potential difference’ between the inside and the outside of the cell

19. Ions are sodium, potassium, calcium and chloride • ‘voltage gated’ • Resting Potential vs. Action potential

20. Chemical Neurotransmission • The flow of neurotransmitter across the synapse • Neurotransmitter; • Made in the pre synaptic neurone • Stored inactively in synaptic vesicles • Released from the synaptic vesicles into the synapse • Binds to receptors • Binds to reuptake transporters to be taken back into the neurone • Is degraded by specific enzymes

22. Neurotransmitters • Acetylcholine (ACh) • Norepinephrine (NE)( also known as noradrenaline) • Dopamine(D) • Serotonin (5HT) • Glutamate • Gamma-aminobutyric acid (GABA)

23. Neurotransmitters • There are two kinds of neurotransmitters – INHIBITORY and EXCITATORY. • stimulate the brain • calm the brain

24. Acetylcholine (ACh) • Cholinergic pathways • thought to be involved in cognition (esp. memory) and our sleep/wake cycle • parasympathetic nervous system regulating bodily functions such as heart rate, digestion, secretion of saliva and bladder function • Alzheimer’s disease and myathesia gravis (weakness of skeletal muscles) • Anti-cholinergic effects

25. Norepinephrine (NE) • attention, alertness and arousal • NE levels fluctuate with sleep and wakefulness and changes in attention and vigilance • mood, affective states and anxiety • antidepressant

26. Dopamine(D) • complex movement and cognition • Emotional responses such as euphoria or pleasure (seen in amphetamine/cocaine use). • Significant role in motor control • EPSE’s

27. Serotonin (5HT) • Great influences on behaviour. • Low serotonin activity is associated with aggression, suicide, impulsive eating and dis-inhibited sexual behaviour • modulating general activity levels of the CNS, particularly the onset of sleep • depression and anxiety disorders • delusions, hallucinations (LSD) • negative symptoms of schizophrenia

28. Glutamate • Glutamate is found in all cells of the body • control the opening of ion channels that allow calcium to pass into nerve cells producing impulses • Blocking of glutamate receptors produces ( eg. By PCP) schizophrenic like symptoms • Over exposure of neurons to glutamate cause cell death seen in stroke and Huntington’s disease (PN).

29. Gamma-aminobutyric acid (GABA) • Inhibitory and its pathways are only found within the CNS. • control excitatory neurotransmitters in the brain and controlling spinal and cerebral reflexes. • anxiety disorders • decreased GABA can lead to seizure activity • Benzodiazepines and barbiturates sedative medication act on GABA